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OCTOBER 1848. 
 
 NEW WORKS 
 
 MEDICINE AND SURGERY, 
 
 PUBLISHED BV 
 
 SAMUEL HIGHLEY, 32, FLEET STREET. 
 
 their Prices and Bates, 
 
 Hif/klefs Getieral Medical Catalogue of Modern Works, with thei 
 
 Corrected to Jahnary 1848 : to which is added, 
 
 A Classifikd Index of Sulyecis, and of ilie Authors who have loritten on them. Price \s. ; 
 
 or tjy post, on receipt of IQ postage stamps. 
 
 GUY'S HOSPITAL REPORTS, 
 
 Vol. VI. Part I. For October 1848. Illustrated with Plates. Svo. price Gs. 
 Contents. 
 Dr. Hughes.— Analysis of 54 Fatal Cases of Pneumonia. 
 Dr. G. Owen Rees.— Case of Hydatid Disease of the Liver. 
 Mr. J. France. — Ophthalmic Cases. 
 
 Mr. J. Birkett.— Observations on Healthy and Morbid Articular Tissues. 
 Mr. B. Wilson.— Case of Opacity of the Cornea, 
 Jlr. Salter.— Case of Tubercular' Disease of the Brain. 
 Dr. T. WiUiams.— On the Laws of Aquatic Breathing. 
 
 Dr. Lever and Dr. Oldham.— Second Scpteunial Report of Guy's Lying-in Charity. 
 Mr. Poland on the Ciliary Ganglion in the Horse. 
 Mr. Taylor.— On the alleged Production of the Phosphate of Lime and Iron iu Xha Egg 
 
 during Incubation. 
 Mr. Cock.— Select Cases of Strangnlated Hernia. 
 
 Dr. Oldham.— On the Use of Bichloride of Mercmy in Hypertrophy, Induration, and 
 Retroversion of the Uterus. 
 
 FEMORAL RUPTURE, and ITS ANATOMY : 
 
 With a New Mode of Operating applicable in cases of Strangulated 
 
 Hernia generally. By JOHN GAY, F.R.C.S. Eng., Surgeon to the Royal Free Hos- 
 pital. 4to. with Plates by Bagg, price 15s. 
 
 SIR A. MORISON'S LECTURES on INSANITY : 
 
 Its Nature, Causes, and Treatment. With numerous illustrative Plates. 
 Edited by his Son, Mr. T. COUTTS MORISON. Svo. price 21s. 
 
 ASinVELL ON DISEASES of WOMEN.— T7m'c/ Edit. 
 
 A Practical Treatise on the Diseases peculiar to Women, illustrated 
 
 by Cases derived from Hospital and Private Practice. By Samuel Ashwell, M.D. 
 late Obstetric Physician and Lecturer to Guy's Hospital. Third Edition, revised and 
 improved, Svo. price 2Is. 
 
 ]\IORGAN ON DISEASES of the Wl'&.—Second Edit. 
 
 Lectures on Diseases of the Eye, delivered at Guy's Hospital. By 
 
 John Mokgan, F.L.S. Illustrated with numerous Coloured Plates. A Xno Edition, 
 carefully revised and enlarged, with Notes, by John F. France, Surgeon of the Eye 
 Infirmary and Lecturer on Ophthalmic Surgeiy at Guy's Hospital. Svo. price IBs. ' 
 
Published by S. Highley, 32, Fleet Street. 
 
 COL. HAMILTON SMITH'S WORK on MAN. 
 
 The Natural History of the Human Species, its Typical Forms, 
 
 Primaeval Distribution, Filiations, and Migrations. Illustrated by numerous coloured 
 Plates. Foolscap 8vo. price 7s. 6d. 
 
 INSANITY TESTED by SCIENCE, 
 
 And shown to be a Disease rarely connected with permanent Organic 
 
 Lesion of the Brain, ar.d on that Account far more susceptible of Cure than has hitherto 
 been supposed. By C. M. BURNETT, M.D. 8vo. price 5s. 
 
 REID'S PHILOSOPHY of DEATH. 
 
 A General, Medical, and Statistical Treatise on the Nature and Causes 
 
 of Human Mortality. By John Reid. 12mo. price 6s. 6d. 
 
 LUGOL ON IODINE, in SCROEULA. 
 
 Essays on the Effects of Iodine in the Treatment of Scrofulous Diseases. 
 Translated from the French of M. LUGOL, by Dr. O'SHAUGHNESSY. 8vo. 8s. 
 
 THE ADVANTAGES of ETHER and CHLOROFORM 
 
 In Operative Sm-gery. An Address delivered to the Hunterian Society, 
 
 Februaiy 1848. By T. B. CURLING, Lectm-er on Sm-gery at the London Hospital, 
 &c. 8vo. price Is. 
 
 PROF!^ SIMPSON on the USE of CHLOROFORM. 
 Account of a New Anaesthetic Agent, as a Substitute for Sulphuric 
 
 Ether, in Surgery and Midwifery. 8vo. price 6d, 
 
 Remarks on the Superinduction of Ansesthesia in Natural and Morbid 
 
 Parturition. 8vo. price 6d. 
 
 Answer to the Religious Objections advanced against the Emplojnnent 
 
 of Anaesthetic Agents in ilidwifery and Surgery. 8vo. price 6d. 
 
 SMITH ON CHLOROFORM. 
 
 Scriptural Authority for the Mitigation of the Pains of Labour by 
 
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 Assistant Teacher of Midmfery at St. Bartholomew's Hospital, &c. 8vo. price Is. 
 
 GRAINGER'S HUNTERIAN ORATION, 1848. 
 
 Observations on the Cultivation of Organic Science; being the 
 Hunterian Oration deUvered February 14, 1848. By R. D. GRAINGER, F.R.S. 
 Bvo. price 2s. 
 
 By the same Author, 
 
 Elements of General Anatomy ; containing an Outliiie of the Organiza- 
 tion of the Human Body. 8vo. price 14s. 
 Observations on the Structure and Functions of the S])inal Cord. Svo. 
 
 price 7s. 
 
 Portrait of j\Ir. Grainger, engraved by Lupton, from a painting by 
 
 Wageman. Price 10s. 6d. (16 inches by 11.) 
 
Published by S. Highley, 82, Fleet Street. 
 
 SPRATT'S OBSTETRIC TABLES.— Fowr^A Editmi. 
 
 These Tables are designed on a similar piinciple to Mr. Tuson's Anato- 
 mical Plates, — the Views being disposed in hinged layers, the raising of which shows a 
 progi-essive advance in the siih^ject under consideration. There are 19 Tables, most 
 of which are made to furnish several successive views by means of this mechanical 
 adaptation. 4to. price 28s. coloured. 
 
 TRANSACTIONS of MEDICAL SOCIETY of LONDON; 
 
 CONTAINING PAPERS ON 
 
 The Use of the Slicroscope in Anatomy, Physiology, and Pathology. By Mr. T. Bell, F.R.S. 
 The Cause and Treatment of Stammering. By Mr. J. Bishop, F.R.S. 
 On the Nervous System, particularly the Excito-motory, or Reflex-Function. By Mr. G.Pilcher. 
 On the' Prevention and Treatment of Apoplexy and Hemiplegia. By Dr. Marshall Hall. 
 Ou the Incubation of Insanity. By Dr. Forbes "Winslow. 
 
 ALSO PAPERS BY 
 
 Dr. J. R. Bennett ; ]\Ir. Bryant ; IMr. Crisp ; Mr. Dendy ; Dr. Garrod ; Mr. Headland ; 
 Mr. Hutchinson; ]\Ir. Liuuecar; Mr. Robarts; Mr. Stedman; Dr. T. Thomson; 
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 BELL ON THE TEETH.— .S'econc^ Editio7i. 
 The Anatomy, Physiology, and Diseases of the Teeth. By Thojias 
 
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 upwards of 100 Figiu-es, illustrative of the Structure, Growth, Diseases, &c. of the Teeth. 
 
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 and Mode of Detecting the various Poisons, IMineral, Vegetable, and AnLmal : to 
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 ANATOMY FOR ARTISTS. 
 
 Hand-Book of Anatomy for Students of the Pine Arts. Containing a 
 
 Description of the Skeleton, and the External Muscles of the Human Figure ; the Action 
 of each Muscle being explained in connection with its Name and Situation. With 
 Illustrations ou Wood. By J. A. Wheeler. New Edition, improved, fcp. Svo. 2s. 6d. 
 
 JOHNSON ON TROPICAL CLIMATES, {Sixth Edit.) 
 
 And their Influence on European Constitutions. 
 With important Additions, by Mr. J. R. MARTIN, late Presidency Sm-geon, &c. Calcutta. 
 Sixth Edition, Svo. 18s. 
 Also by Dr. James Johnson. 
 PRACTICAL RESEARCHES on GOUT. Svo. price 5s. Cd. 
 A TOUR IN IRELAND, with IMeditations and Reflections. Svo. price Ss. 6d. 
 EXCURSIONS TO the PRINCIPAL jMINERAL WATERS of ENGLAND. Svo. 5s. 
 CHANGE of air, or the Pursuit of Health and Recreation. Fourth Edition, Svo. 9s. 
 ECONOMY OF HEALTH, or the Stream of Human Life fi-om the Cradle to the Grave. 
 
 Fourth Edition, Svo. price 6s. 6d. 
 AN ESSAY ON INDIGESTION. Tenth Edition, Svo. price 6s. 6d. 
 
 LIFE OF the late DR. J. JOHNSON, by his Son, IMr. H. J. Johnson. Svo. with 
 Portrait, price 2s. 
 
Published by S. Highley, 32, Fleet Street. 
 
 SIR J. ANNESLEY's DISEASES of INmk.— Second Edit. 
 
 Sketches of the most Prevalent Diseases of India, comprising a Treatise 
 on Epidemic Cholera iu the East, &c. &c. By Sir James Annesley, late of the 
 Madras Medical Establishment. Second Edition, 8vo. price 18s. 
 
 PHARMACOPCEIA HOMCEOPATHICA. 
 
 By Dr. QUIN. Svo. price 7s. 
 
 COOPER'S OSTEOLOGY. 
 
 Lectures on Osteology; including the Ligaments ^vhich connect the 
 
 Bones of the Human Skeleton. By B. B. Cooper, F.R.S. Surgeon to Guy's Hospital, 
 &c. 8vo. with Plates, price 8s. 
 
 KNOX'S ANATOMICAL PLATES. 
 
 A Series of Engravings descriptive of the Anatomy of the Human Body. 
 Engraved by Edward Mitchell. 
 
 The BoncS;, from Sue and Albinus, 4to. cloth, 19s. 
 The Ligaments, from the Caldanis, 4to. cloth, 12s. 
 The Muscles, from Cloquet, 4to. cloth, 25s. 
 The Arteries, from Tiedemann, 4to. cloth, 40s. 
 The Nerves, from Scarpa, 4to. cloth, 32s. 
 
 DIEEFENBACH on the RESTORATION of the NOSE, 
 
 And on the Bemoval of Polypi and other Tumours from the Nostrils. 
 
 Translated from the Geraian, by Dr. Bushnan. Svo. 26 Plates, price 12s. 
 
 CHANGES PRODUCED BY 
 
 CIVILIZATION IN THE NERVOUS SYSTEI\I, 
 
 Considered according to the Evidence of Physiology and the Philosophy 
 
 of History. By ROBERT VERITY, M.D. Second Edition, 8vo. price 6s. 
 
 THE CLINICAL REPERTORY. 
 
 Containing Tabidar Porms for the Collection, Arrangement, Comparison, 
 
 and Analysis of Pathological and Physiological Phenomena. Designed more especially 
 for the Use of Medical Officers of the Navy, and in Civil and IMilitary Hospitals. 
 Affording a Synoptical View of the Connexion and Influence of Meteorological, Topo- 
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 Medicinal Therapeutics and their Effects. Folio, price 25s. 
 
 Also, 
 The Student's Clinical Memorandum Book ; or. Medical Practitioner's 
 Remembrancer and Vade Mecum. Oblong Svo. price 4s. 
 
Published by S. Highley, 32, Fleet Street. 
 
 THE ANATOMICAL REMEMBRANCER, {Third Edit.) 
 
 Or complete Pocket Anatomist. Containing a concise Description of 
 
 the Bones, Ligaments, Muscles, and Viscera ; the Distribution of the Nerves, Blood- 
 vessels, and Absorbents ; the Arrangement of the several Fascia ; the Organs of Gene- 
 ration in the Male and Female ; and the Organs of the Senses. 'irdMit. 32mo. 3s. 6d. 
 
 LIZARS' PRACTICAL SURGERY.— iVe^i; Edition. 
 
 A System of Practical Siu-geiy. Corrected and Enlarged, including all 
 
 the recent Discoveries and Operations. With numerous Explanatory Plates. By 
 John Lizaes, late Professor of Surgery to the Royal College of Surgeons, and Senior 
 Operating Surgeon to the Royal Infirmary of Edinbm-gh. Secotid Edit. 8vo. 129. 6d. 
 
 SMELLIE'S OBSTETRIC PLATES {New Edition) -. 
 Being a Selection from the more Important and Practical Illustrations 
 
 contained in. the original work, with Anatomical Descriptions and Practical Directions. 
 8vo. price 5s. 
 
 SELECTA E PRtESCRIPTIS {Tenth Edition, Improved): 
 
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 The Grammatical Construction of Prescriptions. 
 Rules for the Pronunciation of Pharmaceutical Terms. 
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 A Key, containing tlie same in an Unabbreviated Fonn, with Literal Translation. 
 32mo. price 53. 
 
 ANATOMICAL SKETCHES and DIAGRAMS. 
 
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 References. 
 
 By THOMAS WORMALD and A. M. M^WHINNIE, 
 Teachers of Practical Anatomy at St. Bartholomew's Hospital. 1 vol. 4to. price £1. 6s. 
 
 BOYLE'S DISEASES or AFRICA. 
 
 A Practical ]\Iedico-IIistorical Account of the Western Coast of Africa : 
 
 together with the Symptoms, Causes, and Treatment of the Fevers and otlier Diseases of 
 Western Africa. By James Boyle, late Colonial Sm-geon to Sierra Leone. Svo. jn-ice 12s. 
 
 On the CORRELATION of PHYSICAL FORCES : 
 
 Being the Substance of a Course of Lectm-es delivered in the London 
 Institution. By W. R. GROVE, I\I.A. F.R.S. Royal Svo. price 2s. Gd. 
 
 BILLING'S MEDICINE.— Fo«r/A Edition. 
 First Principles of Medicine. By Archibald Billing, M.D. F.E.S. 
 
 iMcmber of the Senate of the University of Loudon ; Fellow of the Royal College of 
 Physicians, &c. Fourth Edition, Svo. price 10s. Gd. 
 
Published by S. Highley, 32, Fleet Street. 
 
 REES ON DISEASES of CRILDBM^ .—Second Edition. 
 
 The Diseases of Children ; their Symptoms and Treatment. By George 
 
 Augustus Rees, M.D. Surgeon to the General Dispensary for Children. Second Eclitmi, 
 12mo. price 5s. 
 
 GRAY'S SUPPLEMENT to the PHARMACOPCEIA ; 
 
 Being a concise but comprehensive Dispensatory and Manual of Pacts 
 
 and Formulffi for the Chemist and Druggist and General Practitioner. 
 
 NEW edition, hy THEOPHILUS REDWOOD, 
 Professor of Chemistry and Pharmacy to the Phai-maceutical Society of Great Britain. 
 8vo. price £1. 2s. 
 
 PILCHER ON DISEASES or the ^KR.— Third Edition. 
 
 Rensed. 1 volume, octavo, ^^^th Plates. — In the press. 
 
 JUDD ON SYPHILIS and URETHRITIS. 
 
 A Practical Treatise on Urethritis and Sypliihs ; including Observations 
 
 on the Power of the IMenstruous Fluid, and of the Discharge from LeucorrhcEa and 
 Sores to produce Urctlu-itis : mth a variety of Examples, Experiments, Remedies, and 
 Cm-es. By William H. Judd, Surgeon in Ordinary to His Royal Highness Prince 
 Albert; and Sui-gcon-Major in the Scots Fusilier Guai'ds. With numerous coloured 
 Plates. Svo. price £1. 5s. ,.,.,..^,.,^^.,.., .. 
 
 CHILDS ON GONORRHCEA. 
 
 Gonorrhoea and its Consequences. With a short Historical Sketch of 
 
 the Venereal Disease. By G. B. Childs, F.R.C.S. Eng. &o. 12mo. price 4s. 
 
 CURLING ON TETANUS. 
 
 A Treatise on Tetanus. By T. Blizaed Curling^ Lectui-er on Surgery 
 
 and Assistant- Sm-geon to the London Hospital ; Author of " A Treatise on Diseases of 
 the Testis," &c. Svo. price 8s. 
 
 DERMOTT'S DIAGRAMS of the PERITONEUM 
 
 AND PLEURA: 
 
 With Anatomical Descriptions. Svo. coloiu-ed, 4s. 6d. 
 
 Bij the same Author, 
 
 A Concise Description of the Locahty and Distribution of the Arteries 
 
 in the Human Body. 12mo. price 6s. with Plates. 
 
 COX'S COMPANION to the SHIP'S MEDICINE CHEST, 
 
 Particularly adapted for Merchant Yessels, ]\Iissionaries, and Colonists ; 
 
 containing Plain Rules for Taking the Medicines, for Restoring Suspended Animation, 
 and for Ohviating the Effects of Poisons : also Directions for the Treatment of Disloca- 
 tions and Fractures, and for the Treatment of the Asiatic Cholera. Twentieth Edition, 
 revised and enlarged, by R. Davis, M.R.C.S. ISmo. price 2s. 
 
Published by S. Highlit, 32, Fleet Street. 
 
 COWDELL ON PESTILENTIAL CHOLERA. 
 
 A Disquisition on Pestilential Cholera; being an Attempt to explain 
 
 its Phenomena, Natiu-e, Cause, Prevention, and Treatment, by reference to an extrinsic 
 Fungous Origin. By Charles Cq-wdell, M.B. 8vo. price Cs. Gd. 
 
 BENNETT on HYDROCEPHALUS. 
 
 An Essay on the Nature, Diagnosis, and Treatment of. Acute Hydro- 
 cephalus. By J. RiSDON Bennett, M.D. Assistant-Physician to St. Thomas's Hospital. 
 Svo. price 8s. 
 
 SAMPSON'S nOMCEOVATRY. —Second Edition. 
 
 Homoeopathy ; its Principle, Theory, and Practice. 
 By JMarmaduke B. Sampson. Second Edition, enlarged, Svo. price 5s. Gd. 
 
 BY THE SAME AUTHOR, 
 
 Criminal Jui'isprudence considered in relation to Mental Organization. 
 
 Second Edition, enlarged, Svo. price 5s. 
 
 CLUTTERBUCK on INFLAMMATION. 
 
 A Series of Essays on Liflammation and its Varieties. By Henry 
 
 Clutterbuck, M.D. Essay I. — The Natm-al History of the Disease. Svo. piice Ss. 
 
 MORGAN ON INFLAIMMATION. 
 
 Pirst Pi'inciples of Surgery ; being an Outline of Inflammation and its 
 Effects. By G. T. Morgan. Svo. price ISs. 
 
 CLOQUET ON HERNIA;— BY M^VHINNIE. 
 
 An Anatomical Description of the Pai'ts concerned in Inguinal and 
 
 Femoral Heniia. Translated by A. ]\I. M<^Whinnie, Teacher of Practical Anatomy 
 at St. Bartholomew's Hospital. With Explanatory Notes. Royal Svo. Plates, price 5s. 
 
 LAWRENCE'S ANATOMICO-CHIRURGICAL PLATES. 
 
 THE SIZE OF NATURE. 
 
 The NOSE, MOUTH, LARYNX, and FAUCES. 
 
 Aiatomico-Chirurgical Yiews of the Nose, ]\Iouth, Larjiix, and Fauces ; 
 
 ^\ith Explanations and References, and an Anatomical Description of the Parts. By 
 W. Lawrence, F.R.S. Surgeon to St. Bartholomew's Hospital. Folio, price 10s. Gd. 
 plain; £1. Is. coloured. 
 
 The MAI^E and FEMALE PELVIS. 
 
 *** The Subjects were selected by ]\Ir. Lam-ence, who superintended the Dissections, 
 most of which he executed himself, and furnished the Descriptions and Explauatoiy 
 References. Folio, price 10s. Gd. plain ; £1. Is. coloured. 
 
NEW WORKS 
 
 IN 
 
 MEDICINE AND SUEGERT, 
 
 PUBLISHED BY 
 
 SAMUEL HIG HLEY, 32, FLEET STREET. 
 
 Uighlei/'s General Medical Catalogue of Modern Works, with their Prices and Dates, 
 
 Corrected to January 1848 : to which is added, 
 
 A Classtfieu Index of Subjects, and of the Authors who have written on them, Price Is. ; 
 
 or hy fost, on receipt o/" 16 postage stamps. 
 
 On fractures and DISLOCATIONS or the CLAVICLE 
 
 AND SCAPULAR END of the HUjMERUS : 
 
 Being the Jacksonican Prize Essay for 1846. 
 
 By THOMAS CALLAWAY, Jun. F.R.G.S.E. 
 
 Demonstrator of Anatomy at Guy's Hospital, &c. 1 vol. Svo. illustrated with Plates. 
 
 Nearly ready. 
 
 I\IICROSCOPIC ANATOmFo? the HUMAN BODY 
 
 111 Health and Disease. Illustrated with Drawings in Colour. 
 
 By ARTHUR H. HASSALL, M.B. M.R.C.S. F.L.S. &c. 
 
 (Author of a " History of British Eresh-Water Alga?.") 
 
 In 15 Monthly Pai-ts, price 2s. 6d. each.— 13 Parts are now published. 
 
 PHILLIPS' LONDON PHARMACOPCEIA.— F^/i^A Edit. 
 
 A Translation of the Pharmacopoeia CoUegii Eegalis ]\Iedicorum Lon- 
 
 dinensis, MDCCCXXXVL, with copious Notes and Illustrations; also a Table of 
 Chemical Equivalents. By Richard Phillips, F.R.S. L. &E. FftJi Edition, 
 Svo. piice 10s. 6d. 
 
 AN ANATOMICAL STATUETTE, 
 Exhibiting the External ]\Iuscles of the Human Pigure at FuU Length, 
 
 carefully ModeUcd, and EXPRESSLY ADAPTED for the USE of ARTISTS, and 
 others interested in the Study of Anatomy. Accompauied by 
 
 A Key, containing Outline Views of the Statuette in its several Aspects, 
 
 with References to the Names of the Muscles. Price 1 5s. Height, 27 inches. 
 
 PARIS'S PHARMACOLOGIA; (Ninth Edition) 
 
 Being an extended Inquiry into the Operations of ]\Iedicinal Bodies, 
 upon which are founded the Theory and Art of Prescribing. To which are for the first 
 time appended, very extensive Tables of those Medicinal Substances which are Chemically 
 and Physiologically incompatible with each other. By J. A. Paris, M.D. F.R.S. 
 President of the Royal College of Physicians. 8vo. price 20s. 
 
 TRAVERS olTlNELAISIMATION. 
 
 The Physiology of Inflammation and the Healing Process. By 
 Benjamin Travees, F.R.S. Sm-geon Extraordinary to the Queen, &c. Svo. price 7s. 
 
 BRITISH & FOREIGN MEDICaCHIRURG^- REVIEW : 
 
 Being a Combination of " The Medico-Chii-urgical PtCAaew," and " The 
 
 British and Foreign Medical Review" formerly edited by Dr. Forbes. 
 Quarterly, pi'ice 6s. a Number. 
 
 Wilson and Ogiivy, 57, Skinner Street, London. 
 
A HISTORY 
 
 OF THE 
 
 BRITISH 
 
 FRESHWATER ALG^, 
 
 INCLUDING DESCRIPTIONS OF 
 
 THE DESMIDEJ; AND DIATOMACE^. 
 
 WITH 
 
 UPWARDS OF ONE HUNDRED PLATES, 
 
 ILLUSTRATING THE VARIOUS SPECIES. 
 BY 
 
 ARTHUE HILL HASSALL, 
 
 FELLOW OF THE LINN^AN SOCIETV ; 
 
 CEMBEIl OF THE ROVAL COLLEGE OF SURGEONS, LONDON, AND OF THE LONDON 
 
 BOTANICAL SOCIETV ; AND CORRESPONDING MEMBER OF THE DUBLIN 
 
 NATURAL HISTORY SOCIETY. 
 
 IN TWO A^OLUMES. 
 
 VOL. I. 
 
 LONDON: 
 
 S. HIGHLEY, 32. FLEET STREET; 
 
 AND H. BAILLIERE, 219. REGENT STREET. 
 
 EDINBURGH: SUTHERLAND & KNOX, 58. PRINCE'S STREET. 
 
 PARIS : J. B. BAILLIERE. LEIPSIG t T. O. AVEIGEL. 
 
 1845. 
 
London : 
 
 Printed by A. Sfottiswoodt:, 
 
 New-Street-Square. 
 
eljicatioiu 
 
 JAMES SCOTT BOWEEBANK, F.B.S. F.L.S. 
 
 &c. &c. &c. 
 
 Dear Sir, 
 
 It lias long been my intention to dedi- 
 cate to you this humble endeavour to elucidate a 
 difficult and slighted department of Botany, and the 
 time has at length ariived for the fulfilment of this 
 intention. 
 
 In dedicating to you this History of the British 
 Freshwater Alga3, and which is, I believe, the second 
 work Avhich has as yet appeared, which exclusively 
 treats of the Algre of our fresh waters, and the only 
 one devoted to the consideration of the British species, 
 I am actuated, not by private considerations of 
 friendship, but entirely by public motives. 
 
 The skill which you have displayed in the micro- 
 scopic investigation of minute tissues, the generous 
 
 A 2 
 
IV DEDICATION. 
 
 devotion of your time and your money to the ad- 
 vancement of Natural Science, and the deep love 
 with which you are evidently inspired for the works 
 of Creation, have impressed me with a strong respect 
 for your character, and singled you out as the in- 
 dividual with whose name I should particularly de- 
 sire to associate this Work. 
 
 I would therefore beg of you to accept of its 
 dedication, and beheve in 
 
 The high consideration and esteem of 
 
 Yours most sincerely, 
 
 THE AUTHOR. 
 
PREFACE, 
 
 "While the Preface forms the first part of every work, as 
 the name implies, and precedes always the descriptive matter, 
 it is as invariably the last which is written, and the last often 
 to be read. 
 
 Nevertheless there are few portions of a work the endit- 
 ing of which is undertaken with more alacrity than the 
 writing of this same preface — the author's mind being 
 cheered by the near prospect of the completion of his task — 
 it may be of a difficult and an arduous task — in which the 
 obstacles to its successful issue were many, and the result prob- 
 lematical, and the hope of a suitable reward in recompence 
 of his toil either in the form of approbation, if deserved, or 
 money, should the undertaking be of a suflficiently popular 
 character to lead to so substantial a termination. 
 
 There is also another reason which renders the writing of 
 the jDreface an agreeable occupation. It is the opportimity 
 which it affords to the writer to render to those who have 
 aided him in his enquiries the acknowledgments which their 
 liberality and their kindness so strongly claim. 
 
 To Sir W. J. Hooker, Dr. Grcville, Mr. Borrer, j\Ir. 
 Harvey, and the Eev. M. J. Berkeley, names prominently 
 inscribed in the records of the successful cultivators of natural 
 science, the pursuit of which is the most peaceful and the 
 most pleasant of all employments, I am deeply indebted. 
 The two former gentlemen liberally placed at my disposal 
 their valuable collections of freshwater Algce, and j\[r. Harvey 
 and Mr. Berkeley communicated to me numerous imlquc 
 specimens accompanied by valuable remarks. 
 
VI PREFACE. 
 
 To Mr. Jenner, one of the most untiring and successful 
 of Ciyptogamic botanists, and Avhose excellent Flora of 
 Tunbridge Wells is I believe the only one which contains 
 any thing like a complete list of the freshwater AIc/cb, I am 
 likewise greatly indebted for numberless recent specimens of 
 AlffcB, Avhich otherwise I had never seen, as W' ell as for many 
 original and accurate remarks. 
 
 To Dr. G. J. Allman, my highly valued friend, and the 
 talented Professor of Botany in the Dublin University; to 
 Dr. Johnston, of wdiose valuable instructions in zoophy- 
 tology I entertain a grateful remembrance, and to be the 
 pupil of such a master any man might be proud ; to MM. 
 Montaigne, Areschoug, Decaisne, and Mr. Shuttleworth, 
 whose residence in foreign lands precluded unfortunately 
 frequent communication, and from whom therefore I regret 
 that I have not been able to obtain more of that information 
 of which they are so largely possessed ; to INIr. Thwaites, 
 of Bristol, Mr. Sidebotham, of Manchester, Dr. Dickie, of 
 Aberdeen, Mr. M'Colla, of Ireland, and Mr. Thompson, of 
 Belfast, my warmest thanks are due. 
 
 I must not forget also to acknowledge the literary assist- 
 ance which I have derived from Mr. Coj^pin, of Trinity 
 College, Cambridge, nor omit to mention the deep obliga- 
 tion I am under to a lady for the devotion of much time to 
 the shading of many of the plates. 
 
 To Mr. Ross, the eminent optician, with one of whose in- 
 struments most of the nicer observations were made, my 
 acknoTvledgments are likewise due. 
 
 To the Subscribers also to this work I feel much indebted ; 
 their generous patronage has relieved my mind of consider- 
 able anxiety, for it has removed all pecuniary risk to myself, 
 if it has not insured a reward of the same nature. 
 
 Norland Villa, Addison Eoad North, Netting Hill. 
 Julv, 1845. 
 
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INTRODUCTION. 
 
 At the period when the researches hereafter to be detailed 
 were undertaken with a view to publication, viz., in the 
 spring of the year 1840, no department of Cryptogamic 
 Botany was in so unsatisfactory and obscure a state as that 
 of the freshwater Algcs ; the works and memoirs, compara- 
 tively fev/ in number, which had then appeared, cither in this 
 country or on the Continent, abounding with descriptions 
 incomplete, inaccurate, or repetitions of the same productions 
 and facts under different forms and aj^pearances. 
 
 That such should have been the case is not so surprising, 
 when the minuteness of the objects composing the majority 
 of this fertile class of Nature's exhaustless works is considered 
 (the individual parts of many of them being more slender 
 than the human hair), and when, also, the imperfection of 
 the microscopic instruments until recently employed in their 
 investigation, and their changing and fragile character, are 
 taken into account, these circumstances rendering a patient 
 and long-continued study of them necessary. It nevertheless 
 must be regarded as somewhat remarkable, that a field so 
 rich in discovery and of such high interest, until very lately, 
 should have been so little explored ; and that such would 
 have been the case, was certainly not in accordance Avith the 
 expectations of Vaucher when he penned tlic following 
 remarks in the introduction to his eloquent and adnairable 
 
 B 
 
^ INTRODUCTION. 
 
 "Histoire des Conferves cVEau Douce," — admirable, when the 
 epoch at which it was undertaken, and the means at his disposal, 
 are considered. " I wish," he saj-s, at p. 8., " that those who 
 love Botany may see what are our riches in this respect, and 
 what are the discoveries reserved to their perseverance : 
 now that the way is open, more persons should engage them- 
 selves in the study of these objects, and they should be more 
 rapidly studied. If this work excites the attention of the 
 public, there should appear on all sides observations on new 
 ConfervcB and there will be announced, perhaps, productions 
 more singular than those which I describe. This taste for 
 reseaz'ch will not be confined to this one genus, but it will 
 extend to other neighbouring genera, which equally require 
 to be studied ; and this beautiful part of Botany will be in- 
 sensibly drawn from the confusion in which it has for so long 
 a time been found." 
 
 An additional reason why the knowledge of the freshwater 
 Algce, and particularly the Confervoid division of that tribe, 
 should for so long a time have remained in such a confused 
 and imperfect state, consisted in the want of a due appreciation 
 of the value of the characters founded on their reproduction, 
 these being of more importance, in the establishment of the 
 different families, genera and species, than all the other signs 
 and characters derived from attention to other conditions and 
 appearances of these plants. To a right appreciation of the 
 importance of attention to the reproduction of the Conferves 
 it is that the superiority of Vaucher's " Histoire des Conferves 
 d'Eau Douce, " is mainly owing, over other works on the same 
 subject, that close and amiable observer having made — and he 
 was the first, and almost the only one to do so — a knowledge 
 of their reproduction his chief aim and study. Thus the 
 majority of the earlier observers, and some even of recent 
 date, have deemed it sufficient to describe any plant of this 
 class merely from the appearance which it presented on a 
 first examination, without any reference to the stage of de- 
 velopement or condition of that plant ; and have of course 
 expected that the productions thus imperfectly recorded 
 sliould have been recognized Avitli facility by subsequent in- 
 
INTRODUCTION. 3 
 
 vestigators, and handed down to posterity. Sucli expecta- 
 tions, however, it is impossible to realise; and I agree with 
 Vaucher in thinking, that the wisest course to adopt would be 
 (except in some few cases, where the productions can with cer- 
 tainty be determined by otlier characters,) to notice only those 
 species whose reproduction has been satisfactorily made out. 
 
 In the present Avork, the necessity for which is in a 
 measure indicated by the preceding remarks, the characters 
 developed in the state of reproduction are relied upon, in the 
 framing not merely of the families and genera, but also in the 
 definition of species, for which they are even more valuable. 
 
 In this Introduction it is not intended that a, full descrip- 
 tion should be given of the different modes of reproduction 
 and of the structure of the freshwater Al(j(S, the details of 
 these coming under consideration with more propriety when 
 the divisions into families, genera, and si)ecies are treated of. 
 The general particulars of each will, liowever, be now noticed. 
 
 LinuKus supposed that all vegetable productions owed 
 their perpetuity to sexes : he did not, however, assign in his 
 system any fructification to the Conferva;. Had Linna3us, 
 nevertheless, been aware of the highly curious and interesting 
 facts which more recent investigation has made knoAvn, viz., 
 of the phenomenon of the union of two cells, either in dif- 
 ferent or in the same filaments, which so frequently occurs 
 amongst the Conferva (^ee Plates 30 — 50. and 33.), he would 
 doubtless have regarded this commingling as not merely 
 strengthening, but proving the correctness of his views of the 
 sexual character of all plants. But it is to be questioned 
 how far the fact just alluded to would bear any such inter- 
 pretation, its tendency in support of the opinions of the illus- 
 trious Swede being completely neutralised by our acquaintance 
 with otlier facts, and chiefly with this, viz., that in a consi- 
 derable proportion of freshwater species, and probably in the 
 entire of the marine Conferva, no such conjunction of filaments 
 or commingling of the contents of tAvo cells occurs, all the re- 
 quisites for the continuance of these being indisputably con- 
 tained within each cell, no exterior organs of reproduction ever 
 having been discovered in the vast majority of these. Tlio 
 u 2 
 
4 INTRODUCTION. 
 
 exact similarity of the contents of the different cells, — no 
 difference being detected, even with the assistance of the most 
 powerful glasses, — and the principal mode of growth of the 
 Confervas, by the extension and repeated sub-dlvislon of the 
 primary cell, — would tend to lead likewise to a similar con- 
 clusion. 
 
 Notwithstanding the difficulties which He in the way of 
 regarding each cell of a Conferva as the representative of a 
 sex, the frequency with which the phenomenon of union of 
 the filaments, and commixture of the contents of two cells, 
 takes place, cannot be regarded otherwise than as most 
 curious, though the purpose to which It is subservient is so 
 obscure. It may be, that it merely serves to bring a number 
 of the reproductive granules into contact, and which, becoming 
 subsequently clothed with a membrane, are thus the better, 
 preserved until the proper time for their germination arrives. 
 
 Another circumstance opposed to the sexual view as re- 
 gards distinct cells. Is that, in those genera even in which 
 either the cells or their contents unite, exceptions occur in 
 which there is an absence of conjugation of the filaments, 
 and commingling of endochrome or vesicular contents of the 
 cells ; and in other cases there is conjugation, but no mixture 
 of the endochrome of the united cells. 
 
 Thus, so far as can be presumed, the information already 
 acquired would appear to be opposed to the belief in the 
 existence of sexes as applied to cells in the Conferva. A fer- 
 tilization of the sporules does doubtless occur ; and this I 
 believe to be effected through the agency of the following 
 structure, described, nearly as below, in the " Annals of Natural 
 History," vol. xil. p. 20. In this description it will be seen 
 that a double office has been attributed to it; I am now 
 induced to limit its use to the one, the Important one, of 
 fertilization. 
 
 From the high developement of the cells of many Alga, 
 both marine and freshwater, as well as from their extreme 
 transparency, in many species, it might have been supposed 
 that the first discovery of those curious organs, termed cyto- 
 blasts, Avhlch exercise an influence so mysterious on the de- 
 
INTRODUCTION. 5 
 
 vclopement of cells, and whose presence in cellular structure 
 is so constant as to lead to the suspicion that the association 
 of the two organisms is universal, would have been made in 
 this extensive tribe of Nature's wondrous works ; so far, how- 
 ever from this being the case, they have not as yet, so far 
 as I can learn, been noticed in any species of AI(/a ; a 
 description of them, therefore, as they occur in two genera of 
 freshwater Conferva, Zygncma and Vcsiculifera, cannot fail 
 to be of interest. 
 
 In the first of these genera, Zygncma, their structure is 
 exceedingly complicated.* Each cytoblast is solitary, and 
 usually occupies a central situation in each cell of a Zygnema. 
 It consists generally of two membranes, but sometimes 
 there are three ; the innermost of these being either circular 
 or elliptical, (the form varying with the species itself, as well 
 as its condition,) and presenting a nucleated appearance ; and 
 all are sej^arated from each other by distinct Intervals, which 
 are filled with fluid. The surface of the enclosed membrane 
 or membranes is smooth; while that of the external Is ren- 
 dered irregular by the giving ofl^ of numerous tubular pro- 
 longations or radii, which terminate In the spiral tlu'cads 
 formed by mucus, endochrome, and large bright gi-anules, 
 which I regard as the unfertilized zoospores. 
 
 Wishing to have a corroboration of my views respecting 
 the structure of the cy toblastic organ described above, and also 
 to learn as much respecting Its anatomy as possible, I for- 
 warded a specimen of Zygnema nitidum to that able and most 
 obliging observer, J. S. Bowerbank, Esq., whose opinion of 
 Its structure exactly coincides with my own, that gentleman 
 having in particular satisfied himself of the tubular nature of 
 the prolongations sent off by the external membrane, and of 
 their termination In the spiral threads. 
 
 The structure of this curious organ explains with apparent 
 satisfaction one of the offices which It Is destined to dischai-ge, 
 viz., that of a laboratory or stomach. In which the materials 
 necessary for the growth and vitality of the cell and Its con. 
 tents are received and digested, and from A\'hich they arc 
 * See riate n.fig.\,2 3. 
 B 3 
 
6 INTRODUCTION. 
 
 convej^ed, by means of the tubular radii, to those organs by 
 which the materials are to be assimilated. 
 
 The cytoblast, therefore, is at first fixed in the centre of 
 the cell by the ^prolongations which proceed from it : but it 
 happens, that at a certain ej)och these radii disappear, and 
 then the cytoblast floats freely within the cavity of the cell ; 
 the disappearance of the rays, the cessation of the growth of 
 the cells, and the assumption of the characters of reproduction 
 being almost contemporaneous, or, at any rate, events imme- 
 diately consecutive on each other, and the two latter being 
 readily accounted for by the disappearance of the radii. 
 
 The circumstance of the increased developement of the 
 cy toblastic body subsequent to the removal of the radii, gives 
 Aveight, to the opinion that this organ has yet another ofiice 
 to perform, in addition to that of presiding over the growth 
 of the cells ; for were it not so, it might be expected that on 
 the disappearance of the rays it would shrivel up, and at 
 length become absorbed, as is the case with other organs, 
 their allotted duties having been performed : and the ofiice 
 which I would attribute to it, is one even of more imi^ortance 
 than that previously remarked upon, it being no other than 
 the fertilization of the brilliant granules entering into the 
 formation of the spiral threads, and which I regard, as before 
 noticed, as the unfertilized zoospores. 
 
 The adoption of the view which supposes the fertilization 
 of the reproductive bodies by means of the organ whose 
 complicated anatomy has been dwelt upon, would have the 
 effect of removing some grand difliculties in the way of the 
 complete understanding of these most interesting productions. 
 Thus, first, by furnishing a definite organ whereby fertiliza- 
 tion is occasioned, it removes the inability wliich has hitherto 
 been felt to explain in what way the intermingling of bodies, 
 in all respects so similar in organization and appearance as 
 the bright granules of the Conferva seem to be, can be re- 
 garded as giving origin to fertility : secondly, it does away 
 with the anomaly, which has always appeared to me so strange, 
 that a combination of the matter of two cells should iuA^ari- 
 ably take place in certain divisions of the Confervoid tribe of 
 
INTRODUCTION. 7 
 
 productions ; while in other divisions of the same tribe, which 
 could not be supposed to diifer fundamentally from the 
 former, no such phenomenon has hitherto been recognized ; 
 by shewing that this combination is not an essential to the 
 perpetuation of the species : and thirdly, it explains the per- 
 manence of species which have perished before union of the 
 endochrome and formation of spores have taken place. 
 
 I have detected cytoblasts in numerous Zygnemata, but 
 the best species in which to examine them are the larger 
 kinds, such as Zygncma maximum^ Z. nitidum, and Z. belle. 
 Of the genus VesicuUfcra, I have also found it in several 
 species : they cannot always be seen in these, owing to the 
 cells not being so transparent. I doubt not, however, but 
 that they are general in it, as well as other genera of AlgcB, 
 whether marine or freshwater. In this genus it is but a 
 simple vesicle ; at least, I have never observed it in any other 
 state. (See Plate 17. Jig. 6.) 
 
 The Rev. M. J. Berkeley has kindly favoured me with an 
 abstract of a paper by Hugo IMohl on the genus Anthoceros, 
 published in 1839, and inserted in " Linua^a," vol. xiii. p. 273., 
 in the cells of which an organ occurs bearing a considerable 
 external resemblance to the radiated structure met with in 
 the cells of Zygnema. 
 
 The following is a brief outline of the mode of formation 
 of this structure in the genus Anthoceros. When an imma- 
 ture cell of one of the species of this genus is examined, a 
 portion of its interior is seen to be occupied by a layer of 
 green granules, through wliich may be seen a cytoblast, the 
 other portion of the cell being colourless. Treated Avith 
 iodine, the layer formed by green granules, as also the colour- 
 less part of the cell, becomes yellow, showing that the whole 
 Is really lined with a sort of quasi membrane. Gradually the 
 green layer becomes concentrated into two masses, which 
 commence to advance more and more towards the middle of 
 the cells, and the edges of these masses spreading in various 
 degrees over the inner wall of the cell, leave Intervals of 
 various sizes, which give to them a cellular appearance. 
 " The nucleus, or cytoblast," Mold observes, " has no part in 
 
8 INTRODUCTION. 
 
 tills formation. Frequently it is so concealed beneath the 
 green granular mass, that it cannot be seen without some 
 trouble : sometimes it lies near to or between both divisions 
 of the green mass, and then more easily comes into sight ; but 
 at the same time it is observable, that it remains unaltered, 
 and Is foreign to the whole of the slimy structure described 
 above. The latter seems only so far to have a relation to it, 
 that its point of concentration is always at the place where 
 the nucleus lies, and indeed between it and the walls of the 
 mother cell." 
 
 Subsequently, the two masses become divided Into four, 
 and the reticulated appearance produced by the spreading of 
 the masses subsides into radii, which are similar in aspect to 
 those emanating from the cytoblast in the Zygnemata, each 
 arising separately from the masses, and terminating on the 
 inner surface of the cell. Finally, each radiated mass becomes 
 a perfect spore or cell, separated from each other by distinct 
 cellular walls. In which changes similar to those just described 
 take jDlace for the production of other spores. The great 
 similarity in the structure of the incipient spores In the genus 
 Anthoceros with that of the radiated organs In Zygnemay 
 would lead to the supposition that they were identical in their 
 nature ; so far, however, from this being the case, I consider 
 that all analogy between them terminates with the outward 
 resemblance. The difficulties in the way of regarding the 
 structure In Zygnema as an incipient germ or spore, appear to 
 me to be Insuperable ; for the question would Immediately 
 arise, wherefore is it, that since the contents of tico cells 
 generally go to fonn a single spore In the genus Zygnema, 
 and since this radiated organ is present In every cell, that the 
 one Is suppressed, while the other Is destined to give birth to 
 the future Zygnema ? Supposing, however, a satisfactory 
 solution of this difficulty to have been made, still another 
 arises. It is far from being an incontrovertlbly established 
 fact, that the elliptical body formed in Zygnema by the con- 
 centration of the matter of two cells, and usually denominated 
 a spore, does really contain but a single germ. It is far 
 more consistent with known facts to suppose that they are 
 
INTRODUCTION-. 9 
 
 sporangia filled with fertilized sporules ; for tliis is certain, 
 that numerous zoospores are formed within each cell, and 
 which may even be seen through the membrane of the spo- 
 rangia themselves by the aid of a good glass, thcsp zoospores 
 being also identical with the brilliant granules of the Alga. 
 
 The highly interesting observations of Mohl on the genus 
 Anthoceros, the accuracy of Avhich is in no respect questioned 
 by me, do not therefore occasion any modification of the 
 views expressed of the functions of the radiated organ in 
 Zygnema. 
 
 In October, 1843, I learned that Kutzing, in his " Phy- 
 cologia Generalis," published in August of the same year, 
 had noticed and figured the cytoblastic organ just described; 
 and that Meyen had also previously observed it ; where, 
 however, this is recorded, I cannot ascertain. Kutzing thus 
 speaks of it : " Meyen has discovered in the Sjnrogyj'ce a 
 a peculiar central organ. In Sjj. nitida it occurs in the middle 
 of each cell, but is here only to be easily seen in such cells as 
 are larger than ordinary ; and, from that cause, present more 
 lax sj)iral bands. By employing the tincture of iodine, one 
 observes these bodies more easily. Each organ becomes, 
 together with the delicate threads to which it is ajDpcnded, 
 coloured brown by it. It consists of a (Schwal-gedriicken) 
 shghtly comiDressed gonldium, through which may be seen a 
 peculiar nucleus in the midst, and a number of very fine 
 filaments, which extend from it, in a stellate manner, on all 
 sides, and are fastened internally to the spiral bands. At 
 the place where they are attached to these last, their points 
 become somewhat expanded. By means of these stellate 
 filaments the central body becomes suspended in the centre 
 of the cell. M. Schleiden calls these bodies cytoblasts, and 
 is of opinion that the so-called nucleus threads, to which they 
 are attached, are nothing else than very delicate streams of 
 sap, which proceed from the cytoblast, and return to it. 
 Without wishing to throw doubt upon this pretended flow 
 of sap, I must, nevertheless, own that I have not been able 
 to observe it with a microscope of Schick's or Phoflschen's 
 manufacture ; but I have observed that the rays of INIcycn's 
 
10 INTRODUCTION. 
 
 central organ are really sometimes more than mere streams ; 
 at least, that they are mucous threads, since they become 
 tinged brown with the tincture of iodine, and do not in the 
 least alter either their form or position. Schleiden has also, 
 at the same time, observed reticulate, anastamosing little 
 streams upon the central wall of the cell, but especially at 
 the free ends where the green spiral bands cease, and the 
 cells consequently become lighter and more transparent. 
 This appearance, also, has not yet presented itself to me. I 
 have, however, more than ten years ago, seen in the Zygne- 
 viattty motions of very little granules, which resemble those 
 which I have already pointed out in Oedogonium vesicatum 
 and O. capillare. They extend sometimes throughout the 
 entire inner space of the cell, and are especially evident in 
 freshly broken-off terminal cells. That the cytoblast really 
 occasions this motion, I doubt, because it occurs in all 
 the other cells of the Alga which do not possess the central 
 organs." 
 
 Having thus described what I conceive to be the organ 
 whereby the reproductive germs are fertilized, we come now 
 to consider these bodies themselves, which, according to 
 some observers, are twofold — zoospores and spores. We shall 
 speak first of the former. When a portion of a Conferva, 
 for example a Vesiculifera, in an early condition of its growth 
 is placed beneath the microscope, in each cell are observed 
 numerous spherical granules, each having a dark central 
 nucleus, and the size and amount of these varying ex- 
 tremely ; and all being, at this period, connected with each 
 other by a tubular or vascular network.* As the species ap- 
 proaches to a state of maturity, these bodies will be seen to 
 have undergone a considerable increase of size and change of 
 form, they now being no longer spherical, but pyriform, the 
 inflated portions being filled with endochrome, in the midst of 
 which one or two incipient germs can, even at this early 
 period, be observed, and the apices, or, as they have been 
 
 * For aa account of this, see paper by me in " Auuals and Llagazine 
 of Natural History," vol. xii. p. 25. 
 
INTRODUCTION. 1 1 
 
 termed, the rostra, being transparent; near which also is 
 sometimes observed a jjinkish spot simihirto tliat which is seen 
 in the infusory animalcules. The vascular network has now 
 disappeared, and the zoospores lie detached in the cell. At 
 length the granules become perfected, and they are now seen 
 moving restlessly about the interior of the cell, frequently 
 striking against its walls, as though anxious to escape from 
 the confinement of their narrow cell, and to rove about, inde- 
 pendent beings, through the waters, in search of an ap- 
 propriate abiding-place. Having escaped from the cells, 
 Avhich they are enabled to do, not as Agardh supposed, by 
 the multiplied knockings of their beaks against its sides, 
 whereby its fibres become displaced, but either by rupturing 
 its walls, through their increased developement, as in Lyng- 
 bya, Sec, or by some special provision, as in Vesiculifera, 
 Zygnema, &c., they fall into the Avater, through Avhich they 
 speedily begin to move hither and thither ; now progressing 
 in a straight line, with the rostra in advance ; nov/ wheeling- 
 round and pursuing a diiFerent course ; now letting their 
 rostra drop, and oscillating upon them, like (to compare 
 small tilings with great) balloons ere the strings are cut, or 
 like tops, the centripetal force being nearly expended ; now 
 altogether stojiping, and anon resuming their curious and 
 eccentric motions. Truly wonderful is the velocity with 
 which these microscopic objects progress, their relative speed 
 far surpassing that of the fleetest race-horse. After a time, 
 however, which frequently extends to some two or three 
 hours, the motion becomes much retarded, and at length, 
 after faint struggles, entirely ceases, and the zoospores then 
 lie as though dead : not so, nevertheless ; they ha^-e merely lost 
 the poAver of locomotion; the vital principle is still active 
 Avitliin them, and they are seen to expand, to become par- 
 titioned, and, if the species be of an attached kind, each zo- 
 ospore Avill emit from its transparent extremity tAvo or more 
 radicles, whereby it becomes finally and for ever fixed. Strange 
 transition, from the roving life of the animal to the fixed 
 existence of the plant ! In exact correspondence Avith this, 
 is Avhat occurs Avith the Zoophytes. 
 
12 INTRODUCTION. 
 
 So extraordinary were the statements from time to time 
 put forth relative to the spontaneous motion of the reproduc- 
 tive germs of many Algcs — a class of productions always re- 
 garded as vegetable — considered to be, that many observers, 
 and some do even now, refuse to give their belief to their 
 accuracy. So numerous are the observers who have witnessed 
 the singular motions above recorded, that the facts announced 
 in reference to them must be regarded as amongst those 
 which ought to be generally received and adopted. For a 
 long time I myself doubted the reality of the existence of 
 zoospores ; I have now satisfied myself on this head, having 
 repeatedly witnessed their movements in very many Conferva, 
 but never as yet in any species belonging to the conjugative 
 tribe of Alga ; in which, however, Agardh declares himself 
 to have witnessed it. For extended observations on the 
 motion of the zoospores of the Alga, see, in " Annales des 
 Sciences Naturelles (Botanique), 1836," a memoir " Sur la 
 Propagation des Algues. Par J. Gr. Agardh. Extrait." 
 
 It is surprising that, out of the number of those 
 who now study the Alga, so few should have witnessed 
 the singular motion of the zoospores. The spring is the 
 best season for observing these bodies. If, at that time, 
 a number of Alga, collected indiscriminately from different 
 localities, are placed in a vessel of water over-night, and 
 allowed to remain undisturbed until the morning, usually 
 there will be noticed on the surface of the water a thin 
 green pellicle or scum: this, when examined, will be found 
 to consist of the zoospores of different species of Conferva, 
 in all jDOSsible stages of developement. Their motion is 
 most active early in the morning; and they would ajjpear 
 to shun the light, as they are generally met with on the 
 side of the vessel farthest removed therefrom. 
 
 Next in interest to the discovery of the zoospores tlienir- 
 selves, and for Avhicli science was mainly indebted to the 
 researches of J. G. Agardh, is that of the means by which 
 their motion is effected. J. G. Agardli declared that it 
 depended upon the movement of a prolongation or beak, 
 with which each zoospore was said to be furnislied ; others 
 
INTRODUCTION. 13 
 
 liave endeavoured to account for it by reference to the 
 principle of endosmosis ; but neither of these explanations 
 can be deemed satisfactory ; the true cause of it depending, 
 according to the researches of M. linger*, and ]M. Gustavo 
 Thuretf, upon the presence of cilia, similar to those of the 
 infusory animalcules. The following abstract of M. Thuret's 
 paper, on a subject of such high interest, cannot fail of 
 being acceptable. 
 
 The spontaneous movement of the spores of the Algaj 
 has been viewed by a great many observers. In certain 
 cases it is apparent to the unaided sight ; but until now, as 
 declares M. Dujardin, in his " Observateur, ou Microscope " 
 (Paris, 1843), they have not been able to discover by what 
 means the spores swim in the liquid. Nevertheless, the cilia, 
 or filiform tentacles, Avhich serve them as locomotive organs, 
 do not appear to me more difficult to see than the filaments 
 discovered by M, Dujardin In a great number of Infusoria ; 
 and if they have escaped an observer so practised, it is, 
 without doubt, because he has not continued his researches 
 with enough of perseverance, or else, that he has not made 
 them in all the conditions necessary for success. 
 
 In fine, the movement of the sjDores continues for some 
 hours, during which the locomotive organs are in incessant 
 agitation, and in consequence very difficult to distinguish. 
 The use of coloured infusions cannot but detect their exist- 
 ence. When the spore stops, the locomotive organs dis- 
 appear very quickly, without leaving any traces, and some 
 time after, the germination commences. It is necessary 
 then to seize the precise instant when the spores cease to 
 move; or, to make the chances of success greater. It is 
 necessary, Avhen one finds those which move wltli vivacity, 
 to put them in contact with a reagent the action of which is 
 too feeble to alter their form, but enough to stop their 
 movements. Opium and iodine appear to me the agents 
 the most proper to obtain this result. 
 
 * Die Pflanze In Momcnte dex' Thierwerdung. AVien. 1843. 
 t Resenrclies sur les Oiganes Locomoteurs dcs Spores des Algucs. 
 Par M. GaptaYe Thiiret. Ann. des Sciences Nat., IMai et Jiiln, 1843. 
 
14 INTRODUCTION. 
 
 The organization the most simple, is that which is found 
 in the Confervce ; and I have reason to think that it repre- 
 sents a type general to the spores of the AlgcB. I have 
 studied it in the Conferva glomerata and C. rivularis ; tlie 
 spores are altogether alike in both species, and I have seen 
 in the one all that I have observed in the other. Their 
 form is turbinated; the thin extremity, deprived of endo- 
 chrome, to which the name of rostrum or beak has been 
 given, bears two cilia or filiform tentacles, the length of 
 which surpasses that of the spores ; they are the locomotive 
 organs. (See Plate I. j^y. 1, 2.) The spore moves ordinarily 
 with the beak in advance, and turns about in the water with 
 a movement of trepidation, which recalls to mind that which 
 I have observed in the animalcules of the anther of Chara : 
 this analogy applies itself more closely from the resemblance 
 of the organs of locomotion. From time to time the spore 
 suddenly stops ; and often, likewise, it twirls round upon its 
 great axis. The light exerts a marked influence upon the 
 direction of its march. A small quantity of the watery 
 extract of opium is sufficient to arrest their movements. 
 The tentacles are then easily distinguished by a linear power 
 of 240 times (la vue moyenne etant comptee a 25 centi- 
 metres). They are rendered still more visible by employing 
 the alcoholic tincture of iodine, more or less Aveak. If after- 
 wards the spores are left to diy between two plates of glass, 
 the tentacles will not be observed to be altered by the 
 drying, but they come in a manner more satisfactory and 
 positive upon the bottom of the microscope, because they 
 are placed in a mcdiiun less refracting. It is necessary to 
 remark, moreover, (and this observation applies to all spores 
 of the AlgcB which are prepared in this manner,) that, the 
 spore contracting itself by drying, the tentacles appear a 
 little longer. 
 
 It is in the morning more particularly that the greatest 
 number of spores of Confervcs are found in action. Those 
 which one observes after mid-day are for the most part 
 stopped, or have already commenced to germinate. The mo- 
 tionless sjiores all present, towards the beak, a point coloured 
 
INTRODUCTION. 15 
 
 red, which adds still further to their resemblance to certain 
 Infusoria, especially to some Tkecamonadicns. 
 
 The Chcetflphora clegans (var. pisiformis) presents to us 
 a more complicated organization. The beak bears four loco- 
 motive tentacles, instead of two. These spores are very small 
 also, and difficult to observe. (See Plate l.fg. 10.) 
 
 In the ProI/fcTcB ( Conferva vesicata, tumidula, and altcrnata), 
 the organization is still more complicated ; and this difference 
 of the spores is an additional motive for separating these plants 
 from the real Confervce. Two species of this kind have served 
 me in my researches : the first seems to be referrible to Pro- 
 lifera rivularis of M. Leon Le Clerc* ; and the other, a great 
 deal smaller in all its parts, to Prolifera Candollii of the same 
 author. Both have the spores, the beak is rounded, and bears 
 a crown of filiform tentacles (see Plate I.y?^. 13. 18.), which 
 opium or Iodine renders motionless. Their movements are 
 very nearly the same as those of the spores of the Confervce, 
 but much more rapid, by reason of the greater powers of their 
 locomotive organs. When these spores are disposed to ger- 
 minate, they fix themselves by the beak to all tendrils which 
 float in the water, and throw out prolongations or root-like 
 claws, which render them very adherent. The filaments of 
 Prolifera, or Conferva, are often rendered rough with this 
 kind of parasitic vegetation. This fact, ill understood, caused 
 the creation, by Vaucher, of the erroneous appellation of Pro- 
 lifera. If the plant Is removed from the water at the 
 moment of the emission of the spores, they fix themselves 
 around the crystals produced by the evaporation of the liquid ; 
 and when the germination commences, one may see every 
 little crystal charged with a multitude of spores which 
 radiate in all directions. 
 
 The Vauche7-ia, estranged from the genera of which we 
 have been speaking, by Its structure, and by the mode of the 
 formation of Its spores, is distinguished equally by the dis- 
 position of its locomotive organs. The spore is an OAoid 
 
 * Sur ]:i Fructification dii Genre Prolifere. (Mcn)oircs du IMuisciini, 
 torn. iii. p. 462. pi. 23.) 
 
16 INTRODUCTION. 
 
 vesicle which attains the thirtieth of a millemetre in length. 
 It is entirely invested with cilia, rather short, the vibration 
 of which determines the advancing movement of the spore. 
 INI. linger first pointed out these organs in a great and cu- 
 rious work recently published.* The interest of the subject, 
 and the facility of procuring each day fresh specimens, from 
 January until May, determined me to study that plant with 
 care. I proceed to give the result of my observations. 
 
 The tufts of the Vaucheria ( V. clavata) are formed of a 
 network of filaments, cylindrical, branched, continuous, which 
 enclose the green granules (endochrome) and colourless mu- 
 cilage. At the period of the formation of the spore, the 
 extremity of its filaments swell up in the form of a club, and 
 the green matter becomes there condensed, so as to assume a 
 blackish tint. (See Plate II. Jig.2\, 22.) Near the base of 
 the enlargement the granules are seen separated the one from 
 the other, leaving an empty space as if the mucilage had 
 condensed itself in its turn, and driven the granules above 
 and below. This displacement continues until the endo- 
 chrome forms well-defined lines on each side. (See Plate 11. 
 Jig. 23.) Then the great change takes place, which consists 
 in the operation which w^e are about to describe, viz. the 
 separation of the mother plant and of the reproductive body, 
 subsequently clothed with a membrane proper to itself 
 (epispore), possessing a distinct organization. 
 
 Although this phenomenon continues but for a few 
 minutes, it is easy to observe it, since the movement of the 
 granules is almost insensible. INIoreover, the separation is 
 not discontinued after the first time. I have seen the 
 operation thrice repeated upon the same filament. 
 
 The spore then takes the form of fig. 24., that of an elon- 
 gated oval vesicle, whose two divisions are nearly black by 
 the condensation of the endochrome, the inferior division 
 containing much less endochrome. It is then that the crisis 
 approaches : the superior extremity suddenly becomes pro- 
 truded, the granular fluid empties itself into the protruded 
 
 * Die Pflanze in IMomcnte der Thierwerdiuig. Wien. 1843. 
 
INTRODUCTION. 17 
 
 portion which quickly increases in volume, so that the opposite 
 extremity becomes separated from the filament. At the same 
 time the spore commences to turn on its great axis in such a 
 manner, as that all the granules which it contains are seen to 
 pass rapidly from right to left, and from left to right, as 
 though they moved in the interior of a transparent cylinder. 
 The operation by which the spore endeavours to escape 
 occasions a very marked contraction ; but in some few 
 instances it succeeds in disengaging itself, and springs with 
 rapidity into the surrounding liquid. The colourless part, 
 which corresponds to the beak, is always directed in advance. 
 The spore does not cease to turn upon itself, but its progress 
 is somewhat regular, quicker or slower in one direction or 
 another ; in general, it quickly reaches the edge of the glass as 
 though it tried to escape ; sometimes it stops ; then in an 
 instant afterwards it resumes its course. The epispore from 
 Avhich the cilia proceed describes a large granular areola. 
 As to the cilia themselves, they are invisible by reason of the 
 rapidity of their movement ; but we may judge well of their 
 action by putting the spore in an infusion of carmine, indigo, 
 or gum water, &c. Nothing is more curious than to follow 
 its progress in a strong infusion of carmine for example. 
 The coloured granules through which the spore makes its way 
 are driven Avith force by the motion of the cilia; a rapid 
 current is established On each side of the spore, and a long 
 track is described after it. "When it meets with an obstacle, 
 such as the filaments of Zygncma or Vaucheria, it becomes 
 deformed (or is put out of proportion) ; but the motion of the 
 cilia is not arrested. It is also the same when it is com- 
 pressed even to the extent of producing the extravasation of 
 the endochrome ; the vibration of the cilia continues in the 
 part not injured. I have observed many times the emission 
 of the spore in a coloured infusion, and then noticed that the 
 agitation of the granules by the motion of the cilia is not 
 felt until about a fourth part of the spore has been released. 
 
 It is necessarj^, in order the better to see the cilia, to 
 arrest them by means of some reagent, such as opium, iodine, 
 the proto-nitrate of mercury, &c. The effects of tJie watery 
 C 
 
18 INTRODUCTION. 
 
 extract of opium are very remarlcable : the motion is retarded 
 gradually, so that the play of these organs can be Avell dis- 
 tinguished. The iodine water, although it contains but an 
 extremely small quantity of iodine (70V0)' ^^'^ests suddenly 
 the cilia, wliich become plainly visible. The alcoholic 
 tincture of iodine may also be employed, but very Aveak. If 
 afterwards the spore is dried between two plates of glass, the 
 cilia will be sufficiently distinct to be seen by the simple 
 microscope. 
 
 INI. linger has followed the movements of a liberated spore 
 in water during more than two hours. The greatest length 
 of time during which I have observed it with the microscope 
 has been nineteen minutes, and, in general, the motion con- 
 tinues but little more than half of this time : sometimes it ceases 
 almost immediately after the release. But it is necessary to 
 remark, that the spore, being placed upon the object glass, 
 was imprisoned between two plates of glass. The vibration 
 of the cilia continues sometimes after the spore is arrested ; 
 only it is not sufficiently strong to dls^^lace the corpuscle. 
 When at last they cease to move, the contour of the spore 
 undergoes during some instants a sensible alteration, whicli 
 announces, perhaps, the decomposition or the absorption of 
 the vibratile organs. The motionless spore delays not to 
 modify itself once again : it becomes spherical, the green 
 matter distributes Itself equally, and the episporic membrane, 
 in part reabsorbed, at last escapes the sight ; very soon ger- 
 mination commences. 
 
 M. Unger remarks that the escape of almost all the spores 
 takes place towards eight in the morning. Indeed, all the 
 work of the formation of the spore is carried on in the first 
 hours of the day. The tufts which I have gathered the day 
 before, and which presented no indication of the formation 
 being near at hand, were in general covered with spores 
 the next morning ; and after mid-day these were all gathered 
 on the surface of the water beginning to germinate. 
 
 It is easy to follow the progress of this germination under 
 the microscope : the elongation of the filaments progresses, 
 one might say, by eyesiglit ; for I have measured more than 
 
INTRODUCTION. 19 
 
 once an increase of three-twentietlis of a millemetre in an 
 hour. Moreover, the activity of this phenomenon, as of all 
 those which I shall hereafter describe, varies extremely, 
 according to the state of tlie tufts of Vaucheria Avhich have 
 been gathered. It is the same with the diameter of the spores, 
 and the size of the filaments, &c., upon Avliich one is not able to 
 give a certain determination. Therefore, in the figures which 
 I append to this note, all the modifications wdiich the spores 
 of Vaucheria may present, either before or after their emis- 
 sion, ought not to be expected to be found; but I have 
 chosen in my drawings those wliich have appeared to me to 
 represent their most usual and characteristic state. 
 
 The power of germination is moreover carried in Vaucheria 
 to a point which appears to me to surpass all that is observed 
 in the vegetable kingdom. This plant, which consists, to 
 speak truly, but of a single cell, possesses in all its parts the 
 faculty of reproducing itself. The extremities of the fila- 
 ments kept for many weeks, evaporation being prevented, 
 continue to elongate until they have extended them- 
 selves beyond the plate of glass which serves to sustain 
 them. Again, when one of these filaments has undergone 
 lesions in many places, the green matter is seen to become 
 secreted gradually between one end of the injured j^laces and 
 the filament, and to divide itself thus into many little 
 fragments, Avhich form so many distinct individuals emitting 
 lateral prolongations, and not tarrying, without doubt, under 
 favourable circumstances, to reproduce a complete individual. 
 
 The phenomenon of the deliverance of the spore is not always 
 accomplished so regularly as I have described ; sometimes it 
 germinates without quitting the mother plant ; and from this 
 result the strange forms which I have represented iu figures 
 35 and 36. Sometimes also the spore cuts itself into two 
 at the moment of its escape, and so gives birth to two spores, 
 smaller than the others, but capable of germination like 
 them, the one at the exterior, the other at the interior, of the 
 filament. 
 
 The transparent membrane which enclosed the spore, and 
 which became visible after its emission, is destroyed little 
 
20 INTRODUCTION. 
 
 by little. It is perfectly homogeneous ; it is but when 
 it commences to decompose that it takes on a granular ap- 
 pearance ; but it never j)resents those longitudinal strise which 
 I have remarked in that of Conferva and Zygnema. 
 
 I have not perceived any motion in the granules of the en- 
 dochrome, excepting in the case of the rupture of a filament. 
 The granules escape then in jerks ; they often collect them- 
 selves into pellets, and sometimes the mucilage which ac- 
 companies them forms about them a species of membrane ; 
 but these masses of granules have never appeared to me 
 susceptible of organization into reproductive corpuscles ; in a 
 word, never have I seen them germinate. 
 
 The solubility of these granules in alcohol indicates their 
 resinous nature. Sulphuric acid diluted with water con- 
 tracts them into the centre of the filament to a faint ribbon 
 of a brownish green. When this reagent is employed'of 
 greater strength, the granules resolve themselves into a 
 mass of a blackish green ; but the external membrane resists 
 the action of the acid. If recourse is had to ammonia, it 
 often happens that, by a plienoraenon of endosmosis, the fila- 
 ments empty themselves entirely of their granules. This is 
 seen especially in the spores which have commenced to ger- 
 minate; the granules all issue by the extremity of the 
 filament in germination, and the external membrane, which 
 w^as not before visible but at the extremity of this filament, 
 remains entirely empty like to a glass ball. The ammonia 
 possesses also the singular property of imparting a light pink 
 coloration, or vinous red, to cei'tain parts of Vaucheria, par- 
 ticularly to the superior extremity of the spore, when it is at 
 the instant of quitting the mother plant, and this part is 
 less furnished with endochrome than the rest. 
 
 If I have not indicated up to the present time to what 
 species of Vaucheria the observations which I have described 
 apply, it is because the species of this genus are esta- 
 blished upon bad characters. In truth, the organization of 
 the spore, such as I have described it, ajDplies to Vaucheria 
 ovata D. C. = Vaucheria clavata D. C. et linger ; for I have 
 found once, upon the same filament, both this form 
 and that which has been named Vaiicheria sessilis. A 
 
INTRODUCTION. 21 
 
 little time afterwards, the same tufts again have given me 
 Vmicheria hmnata, V. geminata, &c. The appendages 
 that Vaucher regarded as the corpuscles, and which served 
 him to establish his species, arc very different from true 
 spores by the thickness of their envelope, and by the nature 
 of their contents. Crushed under the microscope, tliey 
 permit drops of a very refracting liquid to escape, which 
 alcohol dissolves not, but of which it renders the green 
 colour more brilliant. Sulphuric acid causes it to change to 
 a clear fawn, and iodine to brown. It is true that these 
 appendages are formed, like the spores, by the condensation 
 of the green matter, and that they are separated from the 
 mother plant by a diaphragm ; but I have never found them 
 but upon filaments which have begun to disorganize them- 
 selves, and almost always they decompose with them. Now, 
 since I have constantly gathered in the same locality all the 
 individuals of Vauclicria which have served for my observ- 
 ations, and since I have seen them take successively all the 
 forms represented in the annexed plates, I believe that I 
 ouo-ht to unite VaiLclieria ovata, clavata, sessilis, hamata, 
 terrcstris, geminata, ccBsjntosa, cruciata, into a single species, 
 which I propose to designate under the name of Vauchcria 
 Ungeri, in remembrance of the learned work of the German 
 author and his interesting discovery. 
 
 We have examined four different types of locomotive 
 organs in the spores of the Alga : analogous organs are to 
 be found, without doubt, in a host of plants of this class ; and 
 it is allowable for us to suppose that the different groups 
 present different forms. I should have been able myself to 
 add yet many genera to those which I have mentioned, but 
 I believe that it would be sufficient in this first work to in- 
 dicate the principal types which observation has, up to the 
 present time, made me acquainted with, and to cite for each 
 of them a genus in which this type is found. I would add 
 in conclusion, in order to give more authority to my asser- 
 tions, that ]M. Decaisne has verified the most part of my 
 results ; and that I owe him even certain of the figures which 
 accompany this note. (Ann. des Sciences Nat. 1843.) 
 
22 INTRODUCTION. 
 
 That M. G. Thuret Is in error in uniting all the species of 
 Vauclieria into one, will, by a reference to the descriptions 
 and figures of the genus Vauclieria^ which accompany this 
 work, be at once perceived. 
 
 The animalcules contained in the cells of the filaments, 
 which occupy the interior of the globule of Chara, bear 
 considerable resemblance to the zoospores of the Alga; 
 like them, owing their power of locomotion to the presence 
 of cilia, the anterior extremity of each being furnished Avith 
 two long lashes or cilia (see plate 62., Jig. 5, 6.). If the 
 views of physiologists, however, respecting them be cor- 
 rect, an essential and functional distinction exists between 
 them ; the one being the sporules themselves, and the other 
 the organism, or instruments, whereby those sporules are 
 fertilized. 
 
 While the term zoospore has been applied to the moving 
 sporules of the Alga, the appellation of spore has been con- 
 ferred by some Avriters upon the large and usually elliptical 
 body formed in the different species of the genera Zygnema *, 
 Tyndaridea, Staurocarpus, Mesocarpus, Mougeotia, Vesi- 
 ciiliferay and perhaps Bulbochcete, by the union and con- 
 solidation of the contents of two cells either in the same or 
 diiferent filaments. Concerning the nature of this body, 
 considerable difference of opinion has prevailed and still 
 obtains. Vaucher, who has so accurately described nu- 
 merous species of Conjugatce, thus speaks of it: — "At last, 
 on the 25th Messidor, an IX, in examining the remains of 
 the Conferva jugalis MuUer, which I had followed smce 
 the commencement of spring, I arrived fully and without 
 any doubt at this truth so desired, and which I had made 
 so long and so friutlessly the object of my researches. 
 Almost at the same instant, and in the same day, or at least 
 in the same week, all the grains of the Conferva jugalis, of 
 which I had many thousands, opened themselves by one of 
 their extremities, in the same manner as the two cotyledons 
 of a seed whose embryo has become developed ; and from the 
 
 * See the figures of those genera. 
 
INTRODUCTION. 23 
 
 base of the aperture there issued a green sac, at first very 
 small, but which soon extended itself in such a manner that it 
 surpassed many times the length of the globule. In the 
 interior of this sac appear soon the spires, they being ac- 
 companied by their brilliant points, as in a Conjugata entirely 
 developed. The tube itself exhibits divisions, at first one, 
 afterwards two, then a great number ; at last the Conjiigata 
 detaches itself from its grain, and floats alone in the liquid, 
 and then nearly in size, and with two extremities, which are 
 still pointed, it resembles perfectly the plant which gave it 
 birth." In this description Vaucher is doubtless altogether 
 in error ; and it is difficult to conceive in what way he could 
 have been so imposed upon, a careful microscopic examination 
 of the " spore " alone being quite sufficient to convince the 
 observer that no such dehiscence as that represented by 
 Vaucher could take -pX^ce. M. Decaisne * regards these 
 bodies as the true and only germs of the Cunjugatce or 
 Sunspores, as he has denominated them in removing them 
 from Agardli's extensive class of Zoospores. INIr. Jenner, an 
 indefatigable and excellent observer, writes me word that he 
 has witnessed the growth of these " spores," " which is, by a 
 general extension of the whole investing membrane or 
 membranes, which subsequently divides and subdivides into 
 other cells ; " and Kiitziug also, if I mistake not, states that 
 he has been a witness of their developement in Zygnema and 
 Vesiculifcra, or Q^dogonium. Agardh thus wa'ites in the 
 memoir before alluded to concerning them in the Conjugata, 
 he not being acquainted with the fact of their formation in 
 the true Conferva: — "During the coujimction of a Conjugato, 
 one of the filaments is always giving, the other always re- 
 ceiving ; the spires of the giving filament first become 
 confused; and it is not until after the entrance of the matter 
 of that filament that they become irregular in the other, and 
 then the two masses become confounded together, to form 
 the elliptical or spheroidal bodies. Tlie globules of which 
 the spires are composed do not clear themselves tlie one from 
 
 * Annates dcs Sciences Naturclles, Mai, 1S4'2. 
 
24 INTRODUCTION. 
 
 the otlier during the slow emanation of the matter from the 
 giving filament, and no trace of other motion is observed 
 amongst them. On the contrary, it is in the elliptical body, 
 constituted by the mingled contents of two joints, that I 
 believe to have recognized a phenomenon of locomotion 
 analogous to that described previously in reference to Con- 
 ferva cerea. After many fruitless researches, made for the 
 purpose of seeing the elliptical body develope itself into a 
 new filament, as Vaucher has described, I clearly saw them, 
 on the contrary, dissolve into numerous sporules, endowed 
 with a very rapid motion. Apart from the phenomenon of 
 union of the filaments, which distinguishes the ConjugatcB 
 from all other AlgcB, the only peculiarity in their propagation 
 is, tliat the elliptical bodies from which the sporules proceed 
 remain after many months without any change in them, 
 while they dissolve immediately in the true ConfervceJ^ My 
 own view of the nature of these elliptical bodies precisely 
 coincides with that of Agardh. They are to be considered, I 
 think, as so many sporangia stored with zoospores, which 
 they retain together and preserve from injury itntil the 
 period proper for their developement arrives. Each of them 
 is composed of at least two, and, according to INIeyen, three 
 membranes, these being formed by the gradual Inspissation 
 of the organic mucus enveloping the zoospores. At all 
 events, if they be not sporangia, and if they ever germinate, 
 as some su2:>pose, but Avhich I consider still to be very ques- 
 tionable, a second mode of reproduction, which some have 
 contended for, must be conceded to those plants possessing 
 them ; for it is very certain that the VesicuHf era, in the different 
 species of which are formed bodies in all respects analogous 
 to those of the Conjugatce, are propagated principally, if not 
 exclusively, by zoospores. This is undeniable, and it is but 
 consistent with analogy to suppose, as Agardh has asserted, 
 tliat the ConjugatxB are perpetuated in the same manner. 
 The observation that they dissolve immediately in true Con- 
 fcrvce, does certainly not apply to the true oval or circular 
 organs formed in the true Conferva, with the existence of 
 which Agardh was not acquainted. Tliese are, in all respects. 
 
INTRODUCTION. 25 
 
 similar to those of the Conjugate, and are no less permanent 
 in their nature. 
 
 M. Decaisne combats the idea of the disintegration of the 
 spores of the Alga formed by the union of the endochrome 
 of two cells into zoospores. He states the fact, that the 
 contents of the spores are fluid. This argument is, however, 
 by no means conclusive ; the contents of the undoubted 
 zoosporous Algce are, also, for the most part, fluid; Avhen, 
 however, the full developcment has been attained, the fluid 
 disappears, and the cells are filled with zoospores. The same 
 may occur in the spores of the Zygnemata &c., as asserted to 
 be the case by Agardh. 
 
 ]\I. Decaisne also, in his " Memoir on the Classification of 
 the Alga,'' strongly repudiates the idea of a double mode of 
 reproduction. The spores, IM. Decaisne regards, as already 
 remarked, as the true and only reproductive bodies of those 
 AlgcR in which they occur, and asserts that in these Algce 
 zoospores are never formed. M. Decaisne thus clearly ex- 
 presses himself on this point : " Mais je crois pouvoir avancer 
 aujourd'hui que les zoosporces n'ofFrent jamais de corps re- 
 producteurs resultant d'une concentration de la matiere verte 
 provenant de deux individus." 
 
 This generalization of ]\I. Decaisne is surely untenable, for 
 it is f)crfectiy certain that the usual and most frequent mode 
 of reproduction of the Vesiadiferce, in which spores alto- 
 gether analogous, as before stated, with those of the Conjugates 
 are formed, is by means of zoospores. The motion and de- 
 velopcment of the zoospores of this genus of Alga I have re- 
 peatedly Avitnessed, in such a manner as to preclude all doubt 
 on the question. Now this fact in reference to the Vesiculiferoe, 
 wliicli may be relied on, leads to the adoption of one of the 
 following views, either that there is a double mode of repro- 
 duction in at least a certain number of those Alga in which 
 true spores are formed, viz. by zoospores and spores, or else 
 that the oval bodies termed spores do become disintegrated, 
 in accordance with the statement of Agardh, into numerous 
 zoospores. On the " spores " themselves M. Decaisne has the 
 following remarks : " After the complete organization of the 
 
26 INTRODUCTIOIi. 
 
 reproductive body, the cells are absorbed, at least the spores 
 issue by a rounded aperture which they constantly present at 
 this period. These corpuscles have offered me in this case an 
 ovoid form, and I have seen them without exception issue 
 forth, presenting in advance their colourless extremity. " 
 Of the many hundreds of specimens of Conjugates which I 
 have examined, it has never occurred to me to observe the 
 slightest change in the primary form of the spores or spo- 
 rangia ; loliat they really are seems to me a point yet to be 
 determined, nor have I ever seen the colourless extremity 
 referred to. 
 
 The opinion of the production of the same species from two 
 organs so dissimilar in size and form as the zoospores and 
 spores are, is not so startling when the structure of these 
 is closely considered, as at first sight it might appear. The 
 zoospores being regarded as young cells of ConfervcR^ con- 
 taining only one or two other incipient germs or zoospores, 
 and the spores as cells of larger growth, filled with 
 germs, or zoospores, which have arrived at or near their 
 maturity. 
 
 The organ contained within each capsule of the difl:erent 
 species of the genus Vaucheria, I regard likewise as a sporan- 
 gium filled with zoospores, the horns near it being identical 
 in function with the vesicle already described. The ciliated 
 ovum formed at the extremity of the filaments of Vaucheria 
 is of course difi:erent from the capsular bodies. Having thus 
 given a general outline of the more interesting and leading 
 facts connected with the reproduction of the freshwater Algce, 
 we shall next proceed to the consideration of their structure 
 and modes of growth. 
 
 The structure of the Conferva is exceedingly simple. An 
 outer membrane, transparent as water, invests a number of 
 cells, which exhibit under the microscope not unfrequently 
 a fibrous appearance. These cells do not communicate with 
 each other, although their truncate extremities are always in 
 apposition the one with the other. They contain a thick and 
 generally colourless fluid, in which arc immersed, and some- 
 times scattered irregularly, as in the true Confervm, sometimes 
 
INTRODUCTION. 27 
 
 disposed in starlike forms, and sometimes in spires, a number 
 of vesicular bodies, the Immature zoospores, and in these it is 
 that the colouring matter of the plant chiefly resides. It is 
 from this viscid fluid, the quantity of which is so consider- 
 able, that the Conferva derives its nourishment and means of 
 increase, and not, at least so I consider, from the intercellular 
 substance of Mohl, to whose theory an objection occurs to my 
 mind, in the fact that it is not rational to suppose that the 
 nutritious fluid should be placed external to the cavities of 
 the cells, the contents of Avhich it is destined to nourish. 
 Such is the view usually entertained, I believe, of the 
 general structure of the filamentous AI(/ce. The opinion 
 at present held by Mr. Jenner as to their organization diflx^rs 
 considerably from that just stated, that gentleman declaring 
 that he has, in the Zygnemata, detected a third membrane of a 
 delicate and homogeneous appearance, and that it is by this that 
 the dissepiments are formed, and not by the second, which 
 terminates just at the situation of the joints, between wliich 
 it does not send down any partition walls. Thus the outer 
 membrane he describes as continuous, the second as a series 
 of short tubes, open at their extremities, placed end to end, 
 and the third as. the true cells. Of the accuracy of this 
 ingenious view of the structure of the filaments of the 
 Zygnemata, Sec. I have not as yet been able to satisfy myself. 
 The investing membrane of the cells, one would suppose, 
 would be essential to the existence of a Conferva ; yet M. 
 Areschoug, in an excellent article on Hydrodictyonpcntagonum, 
 states that that curious production does not possess it. In 
 the UlvacecB the cells are not usually placed in linear series, 
 but are scattered through a gelatinous substance, Avhich is 
 usually furnished with an investing membrane. 
 
 As the dlfl:erent cells of a Conferva do not communicate 
 directly with each other, each cell may therefore be regarded 
 as possessing a separate and independent existence. Inasmuch 
 as it contains all the parts requisite for the formation of an 
 entire Conferva. A Conferva then may be regarded, like the 
 associated Zoophyte, as a compound or aggregated being ; and 
 it is to this aggregation of similar parts that the Conferva owe 
 
28 INTRODUCTION. 
 
 their very elegant and beautiful appearance under the micro- 
 scope. Much of the beauty of those most interesting of all 
 Nature's works, the Zoophytes, arises from the same cause. 
 
 Connecting the zoospores with each other, we find in most 
 of the ConfervcB a vascular structure. (See PI. 17.) In the 
 genera Vesiculifera, Zygnema, Microspora* , and doubtless 
 in many other Algce, the zoospores up to a certain period 
 of the developement are connected with each other, and 
 probably with the central cytoblast, by means of a tubular or 
 vascular network, in the angles formed by which the zoospores 
 are situated. This structure is most manifest in Conferva 
 crispata and its allies, and requires, in order that it may be 
 clearly seen, that the developement of the species should be 
 considerably advanced, and the zoospores somewhat scattered. 
 It may generally, however, be easily detected in the genera 
 Vesiculifera and Zygnema. In the latter the tubular formation 
 is not arranged in a reticulated manner, but occupies the 
 centre of each spiral thread. It is by the inosculation of the 
 tubular radii given off by the central cytoblast with this 
 vascular structure, that a direct communication is established 
 between that organ and the zoospores, f 
 
 In addition to the membranes above described, the zoospores, 
 with the vascular network, the sporangia, and the central cyto- 
 blast, two other organs have been noticed in the Confervce, 
 first by INIr. Bowerbank in a species of Zygnema, which I 
 transmitted to him, and subsequently by myself in a variety 
 of other species. The one is cruciform and adherent to the 
 interior AvaU of the cell. (See PI. 17. fig. 1, 2, 3.) It (Mr. 
 Bowerbank remarks) " is the vegetable structure which 
 secretes the raphides." They are probably not definite organs, 
 but crystals. The other body is small, elongated, somewhat 
 curved, and attached to, or lying upon, the plant. (See PI. 17. 
 fig. 1,2,3.) This (Mr. Bowerbank observes) is certainly " a 
 string of minute cytoblasts ; and similar bodies, but more 
 
 * Cladophora Kutzing. 
 
 f See " Annals and Magazine of Natural History," vol. xii. p. 20., for a 
 paper entitled, " Observations on some Points in the Anatomy and Phy- 
 siology of the Freshwater Conferva;." 
 
INTRODUCTION. 29 
 
 curved, are observed In the soft parts of tlie young lips of 
 shells, both marine and freshwater." Several of each of these 
 organs may be found in each cell. 
 
 All the separate and distinct structures and parts entering 
 into the formation of the ConfervcB have now been treated of: 
 certain peculiar adaptations and contrivances still remain to be 
 described, such as the inversion of the extremities of the cells 
 in many Zr/gnemata, the corrugated cells of the Vinculifcra, 
 the layer of fibres surrounding the main stems of some 
 Batrachosj^erms, the ciliary processes met Avith in the same 
 genus and others nearly allied, and the presence of silex in 
 soiiie DiatomacccB. The further notice of these, however, will 
 be postponed until the individual genera come under con- 
 sideration. 
 
 The rapidity of the growth of Confervce, and indeed of all 
 the articulated Algcs, has often been a subject of surprise to 
 many observers of Nature ; and to none more than myself has 
 it occasioned greater astonishment, until I became acquainted 
 with the reason of so surprising a developement of structure. 
 If the filaments of Zygncma nitidum be carefully examined 
 and contrasted together, it will be seen that in some the 
 length of the cells only just exceeds their diameter, and that 
 each cell usually contains four spiral coils, wliieh together 
 perform from seven to eight turns in each, the coils almost 
 touching each other : that in other filaments the length of the 
 cells is more than three times the diameter, but that still each 
 cell contains only the same number of revolutions of the 
 spires, y{z. seven or eight, which now, instead of being nearly 
 in opposition, are widely separated ; thus plainly proving the 
 elongated cells to be derived from the extension of the 
 shorter ones. And again it will be noticed in other filaments, 
 that the cells have returned to their original length, but that 
 each now contains only three or four spiral turns, thus 
 affording manifest proof of the division of the elongated 
 cells, and completing the chain of evidence which establishes 
 to demonstration the existence of the modes of growth to 
 which I have referred throughout all the cells in the species 
 of the genus Zygnema. The proofs now to be adduced, that 
 
30 INTRODUCTION. 
 
 this mode of growth likewise takes place in all other Con- 
 fervce consisting of a single series of cells, are little less con- 
 clusive than those just enumerated. In most of the filaments 
 of these, the cells will be observed to be of various lengths, 
 some twice as long as others, and others again of every inter- 
 mediate length. Now, by means of this law of growth, the 
 variation in the length of the cells is at once and satisfactorily 
 accounted for, w^hich is not to be done in any other way. 
 But this is not all ; the progress of the formation of the 
 septa wliich divide the cells may be frequently traced, 
 a contraction of the cuticle and a division of the endochrome 
 gradually occurring, which is alone sufficient to establish the 
 reality of this law of increase or multiplication of cells in all 
 the true Confervce, and which may be stated to extend 
 likewise to all the other Algce — the Ulvacece, Desmidea, and 
 Diatomacece. In those DesmidecB however which are not 
 filamentous, but which are formed of two symmetrical cells, 
 the multii^lication by growth is often very different. On the 
 separation of the cells from each other, each will throw out a 
 mass of viscid mucous matter, which will go on increasing 
 until it finally takes on all the characters of the primitive 
 cell. Now, particular stress should be laid on this law of 
 developement, since it is evidently very important, inasmuch 
 as it not merely so satisfactorily and so beautifully accounts 
 for the rapid growth of all articulated Algcs — for it is simulta- 
 neously in operation in each of the many hundred cells of which 
 each filament is usually composed — but it teaches us like- 
 wise that much caution is requisite in employing the character 
 of the length of the cells for determining species, as it proves 
 that tliis character, which used formerly to be much relied 
 on for the purpose, is one subject to very great variation. 
 There is a limit, however, to this law of developement which 
 does not in the genus Zygnema allow of more than one or 
 two divisions of each cell, unless indeed the spiral tubes grow 
 likewise in an equal ratio, which may be the case, and then the 
 division of the cells may be frequently repeated. In those 
 Confervce which do not contain spiral tub.es the multiplication 
 of the cells may go on to an almost endless extent. 
 
INTRODUCTION. 31 
 
 Since the above observations were written *, my attention 
 has been directed by Mr. Francis to a lecture by i\I. Morren, 
 inserted in the " Bulletin de 1' Academic Royal des Sciences 
 de Bruxelles," for 1837, from the perusal of which it 
 appears that the growth of many Confcrvce by the division of 
 the cells has been noticed by more than one observer. From 
 this lecture I make the following extracts : — 
 
 "In 1832, M. Dumortier published his memoir upon the 
 structure and developement of plants and vegetables, in which 
 he established with the greatest clearness the fact of the 
 increase of a number of cells by division. His researches 
 were carried on upon Conferva aurea, in which the terminal 
 cell elongates itself more than the others, in order to form in 
 its interior an intermediate production (partition), which 
 divides the cells into two parts, each becoming a new cell." 
 No one could be more explicit, observes M. Morren, Avho 
 goes on to say, "the division of cells by intermediate membranes 
 was examined likewise by M. Hugo Mohl in September 
 1835, upon Conferva glomcrata, &c., a terminal cell of which 
 showed near its centre the commencement of a diaphragm 
 proceeding from the circumference towards the centre." This 
 is in all respects, M. ISIorren remarks in continuation, the 
 observation of INI. Dumortier, but upon another species, and 
 it is all simply the fact previously noticed by myself upon 
 Cruciagenia, but transported from the Diatomacece to the 
 Confei-vcB. 
 
 From this it appears that M. JNIorrcn would claim for 
 himself priority in the discovery of the increase of cells of 
 Confervce by division, but the single observation published 
 in August 1830, upon the genus Cruciagenia, an Alga 
 differing much in structure from true Confervold productions, 
 would hardly suffice to establish for ]\I. Morren this claim 
 any more than would the observation of INIIrbel on the 
 division of the pollen cells give him a claim to the discovery 
 
 * The substance of tlie iireceding remarks, on the growth of the J /^c, 
 is extracted from a portion of an " Essay on the Conferva'," read before 
 the Dublin Natural History Society and inserted in the " Annals and 
 Magazine of Natural History," vol. i. p. 431. 
 
32 INTRODUCTION. 
 
 of the manner of the multiplication of the cells of ConfervcB. 
 Moreover, the investigations of MJM. Dumortier and Hugo 
 Mohl do not go further than to prove, except perhaps the 
 remarks of the latter in reference to one species of the genus 
 Zygnema, that the terminal cell of each filament is successively 
 undergoing division, and not the far more important fact 
 upon which I have so particularly dwelt, that all the cells of 
 a Conferva or articulated Alga are constantly and almost 
 simultaneously undergoing a similar process of multiplication 
 by division. 
 
 M. INIorren afterwards observes in his lecture : " In my 
 memoir on the Closteria, inserted in the " Annales des 
 Sciences Naturelles (partie Botanique), Mai, 1836," I showed 
 that the colouring matter, the endochrome, in consequence of 
 polarization, divides itself in each cell into two opposite 
 masses, which become separated by the secretion of a trans- 
 parent liquid (a true intercellular substance, in which is 
 formed the double diajshragm, which by separating produces 
 slowly the dislocation of the two cones of the Closterium. 
 
 " I have since observed," continues ISI. INIorren, " all the 
 particulars of this phenomenon of the formation of interme- 
 diate partitions in the Confervce, my observations having been 
 made on Conferva dissiliens. The articulations in this are 
 very short, equalling their diameter or even less than tlais. 
 Now there is in these a green mass at first uniform, in which 
 appear peculiar globules, which become transparent vesicles, 
 more yellow than the rest of the colouring matter, presenting 
 finally spots more obscure, almost brown or red at the centre. 
 These bodies appear to me to be the male apparatus exer- 
 cising a true fecundation upon the rest of the endochrome. 
 But this mass, when the male cellules are developed, polarizes 
 and flows towards the two poles of the parent or general 
 cell. Then this celliile is seen to become elongated under 
 the dominion of this ebbing or polarization, and between 
 these two masses a ti'ansparent space is manifest. The com- 
 pressorium has proved to me that there is here a mucous 
 fluid or intercellular substance. Now upon the peri2:)hery of 
 this substance the condensation operates ; at first little b}^ 
 
1^'TRODUCTION. 33 
 
 little it proceeds towards the centre, and in place of a zone of 
 liquid substance there is a membrane duly organized and 
 fit to become divided into two membranes, each mass of 
 endochrome having its wall, or more correctly, its proper 
 membrane." In this account no mention is made as to 
 whether the cells, the division of which M. Morren witnessed, 
 were terminal or not. 
 
 ]\Iy own views of the phenomenon of the division of the 
 cells of Conferva, and of the explanation to be offered of it, 
 differ considerably from those of i\I. Morren. All the cells 
 of a Conferva, until it has reached a state of maturity, are 
 continually increasing in lenyth ; and it is only in certain cells 
 which have exceeded their standard length, that the gradual 
 separation of the endochrome into two masses is seen to 
 occur, and a transparent space to be left between them ; this 
 space is not, however, in ray opinion, occupied by any form- 
 ative intercellular matter, such as that referred to by M. 
 Morren, who, in his explanation, asserts that the polarization 
 and separation of the endochrome first takes j)lace, and that 
 afterwards the cells begin to grow. The first indication of 
 the formation of the partitions which are to divide the parent 
 cell into two, is not visible until after the separation of the 
 endochrome, and appears to consist in a solution of a portion 
 of the periphery of the centre of that cell, the divided edges 
 of the cell then becoming inverted separately, and growing 
 towards the centre, where they coalesce. Thus, according to 
 this view, the partitions of the cells are not, as M. Morren 
 would assert, new gro'wths or formations, but merely an 
 extension of the separated margins of the parent cell. 
 
 A second mode of development *, of considerable import- 
 ance as regards the classification and description of the Algce, 
 still remains to be described. In many species of Conferva 
 more especially in the branched kinds, and in numerous other 
 Algce; in the species of the genera Vesiculifera, Lynghi/a, 
 Meloseira, Fragilaria, Sec, there is not only a longitudinal de- 
 velopement of the cells, but there is likewise a lateral growth 
 
 * See Annals of Nat. Hist. vol. xi. p. 359. 
 D 
 
34 INTRODUCTION. 
 
 of them ; so that if we examine any species in which this law 
 is known to exist, we shall observe, first, that the filaments 
 differ considerably in diameter in the same specimens ; se- 
 condly, if the species be a branched one, that the largest 
 filaments are near the centre of the specimen ; and, thirdly, 
 that the diameter of all the filaments, whether they be near 
 the centre or circumference, gradually decreases from base 
 to apex ; the observation of these three facts proving the 
 existence of the law of the lateral developement of cells, 
 and also showing it to be in the degree of their age. The 
 proportions of a specimen of a branched Conferva, therefore, 
 are in miniature those of a tree or shrub. This law has no 
 existence in the conjugating Conferva in the genera Bulbo- 
 chcBte and Desmidium, and in the majority of OscillatoricB. One 
 or two other observations still remain to be made in re- 
 ference to cells, to complete the intei'esting subject of the 
 developement of the Confervce, Prior to the discovery of the 
 multiplication of cells by division, the opinion was generally 
 entertained that each cell was at its conmiencement very 
 small, and that it increased little by little, until it attained 
 its perfect developement ; and this is the case with the cells 
 of parenchymatous tissue; but in the examples w'here the 
 multiplication of cells takes place by division of those cells 
 which have already become great, nature takes a means for 
 the fulfilment of its end, altogether diiferent, but not less 
 effectual. 
 
 It has already been mentioned that the different series of 
 cells, of wdiich the Confervce are composed, are all enveloped 
 in a continuous membrane, w^hich serves to bind them to- 
 gether; there would appear, however, according to the re- 
 searches of Agardh and Hugo Mohl, to be another and direct 
 bond of union between the cells, not merely of the AlgaB, 
 but of all other plants, this consisting in an adhesive sub- 
 stance which INIohl has denominated " intercellular," by which 
 they are firmly united to each other. The same substance is 
 found coating the surfaces of the pollen granules, binding 
 them into masses. 
 
 Having thus traced the developement of the Confervce. from 
 
INTRODUCTION. 35 
 
 tlieir earliest period, vi;^. from the condition of zoospores, and 
 having examined their structure and modes of growth, we 
 shall next proceed to make a few remarks upon their dis- 
 tribution and vitality.* 
 
 Not amongst the least beautiful of the many minute oj- 
 ganizations, whose Intimate structure the microscope, which . 
 has so wonderfully extended of late our knowledge of the 
 natural world, has revealed to us, are the freshwater AlgcB^ 
 and yet the majority of these constitute the rejected and 
 desi^ised, by all but the true naturalist, scum and slime of our 
 still and soft waters; but although many freshwater Algce 
 are, for an obvious and benevolent purpose, hereafter to be 
 mentioned, ordained by their Great Designer to be the tenants 
 of our impure and stagnant waters, there are other species 
 which ai'e met with only In fresh and running streams, ad- 
 hering by one extremity to some object of attachment, the 
 other floating freely In the surrounding fluid medium in the 
 course of the stream, whose Impetuosity and strength these 
 frail productions seem at first sight but 111 able to Avithstand. 
 They find their protection, however, not less In the flexibility 
 than In the tenacity of their structure. This Is the case 
 with the Lemanm, Lyiighya crispa, and with the beautiful 
 Conferva cjlomcrata, which delight In the J5urest and most rapid 
 streams. The Ectosperma clavata of Vaucher, known by Its 
 globular form and dark green shining apjjearance. Is met 
 with only In the course of the waterfall or cataract, sus- 
 taining unharmed the whole force and weight of the foaming 
 waters which pour over it. The Batrachosperms, the most 
 elegant of all our freshwater Conferva^ also usually dwell 
 in pure water, but are obliged, for the most part, from the 
 delicacy of their conformation, to confine themselves to such 
 streams and rivulets as are slow, and possess but little 
 strength ; while some Confervce, as many species of Zyg- 
 iiemata, Tyndaridea and JSlougeotia, are almost exclusively 
 confined to marshes, ditches, or shallow and extended pools, 
 
 * For a liiglily interesting memoir upon the connection of the cells of 
 plants, by Hugo Mohl, see Annales des Sciences Naturelles, second series, 
 torn. viii. (Botanique). 
 
 D 2 
 
36 INTRODUCTION. 
 
 which dry up and disappear at the approach of summer, the 
 species inhabiting them having performed their allotted office 
 in the economy of nature, disappearing likewise, their lives 
 terminating with the exigency which called them into ex- 
 istence ; others are usually met with in the perennial waters 
 of our deep and clear lakes and ponds, and, though not them- 
 selves perennial, yet have probably a life of somewhat 
 longer duration extended to them ; as, for example, some of 
 the larger Zygnemata^ certain species of Draparnaldia 
 and Lynghya and Conf. crispata. I am inclined to think, 
 however, that the lives of but few species of freshwater 
 AlgcB extend beyond the period of a year, while it is very 
 certain that very many perish in a few months, or even 
 weeks, from the time of birth, in which case I can assert 
 from observation, that the species perishing thus early are 
 frequently reproduced in the course of the summer, when 
 the circumstances are favourable, some two or three times. 
 Very many Confervce. die in the spring from the drying up 
 of the waters in which they dwell, at which season it is 
 wisely ordained that such species should mature their seeds ; 
 amongst these may be mentioned many species of the genera 
 Zygnema, Tyndaridea and Vaucheria ; others die at the ap- 
 proach of winter, but not all; a few linger through the 
 greater part of this season so unfavourable to the exercise of 
 the vital functions of plants. There are other species, again, 
 which do not require to be constantly immersed in water, 
 but are found upon those soUs and in situations which retain 
 moisture for some time, as upon shaded and clayey pathways, 
 at the roots of trees, on banks, thatch, and at the bottom of 
 palings, the drippings from which they receive. In such lo- 
 calities, Co7if. ericetorum, some Lynghyece, Scytonemea, many 
 Oscillatorice and Nostoclmiece are met with. In these plants, 
 the strength of the vital principle must be very great, for 
 their filaments may be dried up for a considerable time ; but 
 on the application of moisture, they soon recover their 
 healthy appearance. 
 
 So abundant are the productions under our consideration, 
 that there is not a ditch or pool of any extent or standing 
 
INTRODUCTION. 37 
 
 but furnishes one or more species, and even our mineral 
 springs are not entirely free from them. From the uniform 
 nature of the element which the majority of the freshwater 
 AlgcB inhabit, it may be confidently anticipated that very 
 many of the species described in this work will, wdien the 
 Algcs come to be studied witli that diligence and care which 
 they so well merit, be found in most of the continental 
 countries. Of the species described by Vauchcr, a consider- 
 able proportion are likewise indigenous to Great Britain. 
 
 Most of the freshwater Confervas, when in a healthy state, 
 are of a green colour, the shade being often extremely rich 
 and beautiful, but varying wuth the condition of the species, 
 and with the species themselves. The occurrence of this 
 colour is comparatively rare amongst the marine Algce, in 
 which it is usually more or less red or brown, the colouring 
 matter being operated upon probably by free acids in the salt 
 %vater. 
 
 Sometimes the Conferva are diffused through the waters 
 of a pond or lake, imparting to it a bright green colour, and 
 causing it to resemble so much of the purer element — the 
 sea. At others, the filaments of a number of different species 
 wiU become entangled, and float together upon the surface of 
 the water, wafted hither and thither by the wind, like a 
 beautiful cloud, the softness and richness of the tints of wdiich 
 a painter would be immortalized could he imitate. It is only 
 during the early spring months, however, that the Confcrv(B 
 retain this depth and beauty of colouring; for under the 
 influence of the rays of the summer sun, they very soon fade 
 and bleach, becoming ultimately, when the water in which 
 they dwell has evaporated, converted into the paper-like 
 substance which has recently attracted so much attention on 
 the Continent; indeed, so like to artificial paper is this 
 natural formation, that I feel assured an useful paper might, 
 by an artificial process, be made during the summer months 
 out of many abundant species of Conferva. 
 
 The Conferva, like most other productions, whether animal 
 or vegetable, whose organization is feeble, cling tenaciously 
 to life ; thus, they may be torn and cut up into a thousand 
 D 3 
 
38 INTRODUCTION. 
 
 pieces, and yet each separated portion will retain its vitality 
 unimpaired, and go on increasing as before; but this is 
 owing, in a measure, also to the fact of each cell in the 
 series enjoying an independent vitality. They also sustain, 
 unharmed, considerable vicissitudes of weather, notwithstand- 
 ing which they are, however, regular barometers, rising and 
 sinking in the fluid medium which surrounds them alter- 
 nately, either as the sun shines, and warmth is diffused, or as 
 clouds and rain obscure the sky, and cold prevails. In this 
 way, too, they protect themselves in a great measure from 
 the alternations of weather, the water being much Avarmer 
 beneath the surface than on it. This power which the 
 Conferva possess of rising and sinking in water, in cor- 
 respondence with atmospheric changes, is to be explained by 
 reference to their specific gravity, which is in proportion to 
 the activity with which the function of respiration is carried 
 on. During the autumnal and early spring months, the 
 ConfervcB remain almost entirely at the bottom of the water, 
 except when tempted by a few sunny days to rise to the 
 surface, and expose themselves to the contact of the air, so 
 that the naturalist engaged in the investigation of these 
 productions is often surprised on visiting ponds in which he 
 beheld the day previously Confervas floating on the surface 
 in considerable quantity, to find that on his next visit they 
 have all vanished. The Conferva are also amongst the first, 
 if not the very first, subjects of creation to feel the approach 
 of more genial weather, beginning to vegetate sometimes so 
 early as the months of January or February. 
 
 In the preceding pages it has been assumed that the fresh- 
 water Alg(B are really Avhat many observers have been 
 inclined to doubt, viz. vegetable productions or plants, they 
 being led so to do, first, from the curious and extraordinary 
 motions of the zoospores already described, and second, from 
 the peculiar and animal foetor which the different species 
 exhale during decomposition. Their true position in the 
 scale of organized beings has been, it seems to me, satis- 
 factorily determined, not merely by reference to certain re- 
 semblances which they bear to vegetables in appearance and 
 
INTRODUCTION. 39 
 
 organization, but also and mainly by chemical analysis. In 
 the 14th volume of the second scries of the " Annales des 
 Sciences Naturellcs (Botanique, 1840)" is an elaborate and 
 highly interesting memoir by M. Peyeu, on the chemical 
 composition of vegetable tissue. In this memoir, M. Peyen 
 establishes a distinction between animals and vegetables 
 based upon the chemical difference which he has ascertained 
 to exist between the cellular membranes of the respective 
 divisions of the organic world. The vegetable tissue, M. 
 Peyen finds, to exhibit invariably a ternary composition, 
 that is, it is composed of three out of the four elementary 
 constituents of which all bodies are formed, viz. carbon, 
 hydrogen, and oxygen in nearly fixed proportions, as follows : — 
 carbon 44, hydrogen 6, oxygen 50. The composition of the 
 animal tissue or membrane, on the contrary, is as invai'iably 
 QUATERNARY, or formed of all the elementary constituents in 
 less fixed proportions. This generalization is arrived at by 
 an extensive and careful analysis, not only of animal sub- 
 stances, but also of examples of most of the families and 
 orders of Phanerogamic and Cryptogamic plants. Amongst 
 the freshwater AI(/cb an analysis was made of Coiif. rivularis, 
 Oscillaioj-ia, and Cham, these all offering the same result as 
 the other analyses of vegetable tissue, and therefore being con- 
 clusive as to the vegetable character of the Confervoid division 
 of the AlgcB. It is to be regretted that an analysis was not 
 made of the Desmidece. and Diatornece, with a view to de- 
 termine more certainly than has yet been done their position 
 in the scale of beings. That the Desmidece. are really vege- 
 table productions, scarcely a doubt remains, iodine demon- 
 strating the presence of starch in abundance in the contents 
 of their cells. 
 
 The following are the steps adopted by ]\I. Peyen in order 
 to free the membrane of the Conferva rivularis and Oscillaforia 
 from all extraneous matter, and thus to prepare it for 
 analysis : — 
 
 " I tried next to test, with the same object in view, very 
 many Confervce. Soda, by dissolving Avith heat the investing 
 membrane of the filaments of Conferva rivularis, separated 
 
40 INTRODUCTION. 
 
 from each other the long cells, which, applied end to end, and 
 more or less filled with green matter, occupy all its tubular 
 capacity." 
 
 " In order to remove entirely the green matter, it was 
 necessary to open the cells which retained or held it, by 
 means of dissolvents. I contrived to effect this by squeezing 
 slightly together moistened ConfervcB, drying the mass, 
 afterwards submitting it to the action of lime, then alcohol, 
 ammonia, solutions of soda and potass diluted, removed 
 the azotized substances and green matter in solution. 
 Chlorine effaced the last traces by eliminating also a 
 brown substance ; hydrochloric acid, Avater, ether, and 
 alcohol perfected the purification by removing carbonate of 
 lime and fatty substances. The purified membranes of 
 Conferva rivularis and Oscillatoria presented then the com- 
 position of the other vegetable tissues." 
 
 The nature of the contents of the cells of the ConfervcB 
 is, it would appear by the preceding remarks, more complicated 
 than one would be led to suppose from a consideration of 
 the structure of the cells themselves. Starch is found in 
 them in considerable quantity, azotized substances, a fatty 
 matter, a colouring substance, and an odoriferous principle, 
 as well as salts. The Chara, M. Peyen remarks, contains 
 granules of starch, green azotized bodies, soluble azotized 
 substances, a fatty matter, a colouring substance, an 
 odoriferous principle, recalling the marshy odom' of many 
 Conferva, cliloride of potassium, carbonate of lime adherent 
 to the exterior of the membrane, and slhca. 
 
 Nitrogen, as is now well known, is the animalizing principle. 
 It is found, however, not as an organic constituent, but 
 merely as a product in small quantities throughout the 
 vegetable kingdom. It is especially noticed in the seeds of 
 the GraminecB, in the Fungi, and in the delicate reproductive 
 organs, in the pollen, &c. As a rule it has been remarked 
 that its presence is constant in the young parts and organs 
 of plants in which there is always a high degree of vitality, 
 in the establishment and maintenance of which this substance 
 would appear to be an essential element. M. Peyen, in the 
 
INTRODUCTION. 41 
 
 Memoir already referred to, lays down the following pro- 
 position with regard to nitrogen. 
 
 " In the two kingdoms, the bodies which admit azote to 
 the number of their principal constituents, are indispensable 
 to the accomplishment of the laws of life." 
 
 A distinction may be established between animals and 
 vegetables, moreover, by a consideration of the effects of 
 different reagents applied to their tissue. This distinction is, 
 however, less satisfactory than that derived from a knowledge 
 of their chemical composition. " Vegetable membranes," 
 M. Peyen remarks, "which are well aggregated, are not 
 sensibly alterable in the presence of a host of reagents, such 
 as iodine, chlorine, the alkalies, and acids diluted, tannin, 
 many neutral salts, alcohol, and creosote, which colour, 
 attack, dissolve, or strongly contract the membranes of 
 animals, but the distinction which is founded upon their 
 elementary composition is still more certain." 
 
 The same agent, iodine, seems to detect the presence of the 
 product starch, and of the element azote, by imparting to 
 starch globules a blue tint, and to those substances contain- 
 ing azote a yellow coloration. 
 
 A few remarks upon the subject of cu-culation may here 
 be introduced. If we except the order Characece, to be 
 described in its proper place, but few traces of a circulation 
 in the freshwater ConfervcB exist. There is probably a 
 motion of fluid in the tubular structure which connects the 
 light green granules of the Algce, and in the vajs, which 
 proceed from the central organ in Zygnema ; there is also, 
 doubtless, an action of endosmosis and exosmosis carried on 
 between the different contents of the cells, and between these 
 and the water in w^hich the Confervce dwell. 
 
 The uses of the freshw\ater Confervcs may be regarded as 
 fourfold ; two of these uses pertain to the animal creation in 
 general, the other two to man in particular. 
 
 The first and most obvious use to notice is, the abundant 
 supply of delicate and nutritious food which they furnish to 
 myriads of the inhabitants of our fresh waters. It is scarcely 
 
42 INTRODUCTION. 
 
 possible to place a fragment of any Conferva under the micro- 
 scope, without perceiving some of the numerous forms of life 
 which dwell amongst its filaments ; and the structure of many of 
 which is so beautifully adapted to the wants of the creatures, 
 and to the existence which they are destined to lead, as to 
 raise in the mind of the beholder the liveliest feelings of 
 admiration. 
 
 The second purpose to which the Confervce. are sub- 
 servient is one of great importance, being the purification 
 of the fluid in which they dwell, laden, as it frequently is, 
 with various deleterious gases, arising from the death and 
 decomposition of various animal and vegetable substances; 
 thus deriving their own origin, for the most part, in the 
 midst of impurity, they are the agents employed in removing 
 this impurity, which salutary office they perform in the 
 following way. Amongst the most noxious of these gases to 
 animal life are carbonic acid and carburetted hydrogen ; now 
 carbon, the base of these, constitutes the pabulum, or food, of 
 plants. These two gases, then, the Conferva decompose, 
 retaining the carbon for their own support, and setting free 
 the oxygen and hydrogen ; thus not merely decomposing and 
 removing what is hurtful, but restoring to the water oxygen, 
 the essential to all animal life whether found in air or Avater. 
 Seeing, then, the important purpose which these apparently 
 frail and insignificant productions fulfil, who is there who 
 would venture to remove even this one small and remote link 
 from the chain of Nature's works, and would be answerable 
 for the consequeuces of its removal? Who can tell what 
 baneful influence might not arise, and spread disease and death 
 through whole districts? a calamity which, even as things 
 are now ordained, is occasionally permitted to overtake us. 
 Should any Individual be sceptical as to the influence of 
 these productions, and whether a respiration of the kind I 
 have alluded to, and attended with the same results, really 
 occurs, let him put into a tumbler of water a little of the 
 first Conferva which he may meet with in his next ramble, 
 and, placing It in the rays of the sun, watch it for a short 
 
INTRODUCTION. 43 
 
 time ; he will soon observe globules of a gas, at first small, 
 but soon becoming larger, to collect upon the surface of the 
 filaments, which, when they have attained a sufficient size, 
 will quit their attachment, rise to the surface of the water, 
 and at last lose themselves in the surrounding air. This 
 will, I think, satisfy him that a respiration of some kind is 
 carried on ; and should he wish to ascertain the nature of the 
 gas thus eliminated, whether it be really oxygen or not, this 
 may be done by procuring a considerable quantity of any 
 floating species of Conferva, and placing it in a trough of 
 water, over which should be put a glass jar also filled with 
 water, having an air-tight collar adapted to it, so disposed as 
 to catch the gaseous globules as they ascend. As soon as 
 the glass jar becomes filled with the gas, let the air-tight 
 collar be rem.oved and a piece of ignited phosphorus be 
 quickly plunged into the interior of the jar, when the brilliant 
 and dazzling combustion Wiilch will Instantaneously ensue 
 will afford a proof conclusive of the nature of the elimination. 
 The honour of this discovery, if it can be deemed one, for it 
 is but the extended application of the common principle of 
 the respiration of plants generally, is in this country attri- 
 buted to Priestley ; but so obvious Is it that It scarcely re- 
 quu'ed the penetration of a mind like his for its detection : 
 Yaucher alludes to it cursorily. 
 
 The third use of the ConfcrvcB is a moral one. Every 
 created thing, rightly viewed. Is capable of Imparting this 
 moral lesson, be it the kingly lion or the spurned reptile; 
 the beautiful and scented flower, or the more humble pro- 
 ductions Avhich have been engaging our attention. There is 
 no imperfection acknowledged in nature, nor are there, 
 strictly, degrees of comparison ; everything Is superlative, 
 is best and perfect from the hands of God Avho made it, ahke 
 unsurpassable and Inimitable. 
 
 Then, lastly, there Is the Intellectual benefit derived by those 
 who study this or any branch of Nature's works. There are 
 those who regard the pursuits of natural history as trivial and 
 tending to no useful purpose ; but these are but superficial ob- 
 
44 INTKODUCTION. 
 
 servers, with hearts and minds alike incapable of appreciating 
 the depths and hidden beauties of the study. I maintain, in 
 opposition to these, that there is room in the contemplation 
 of, and search after, the laws and phenomena of animal and 
 vegetable life and growth, for the exercise of an enlarged 
 and enlightened understanding. 
 
HISTORY 
 
 BRITISH FBESHWATER ALQM. 
 
"II y a dans cliaque plante bien examinee une preuve vivante de 
 I'existence du grand Etre que governe cet univers. Les divers arrange- 
 ments qui presentent les organes sont autant de petits problemes pro- 
 poses par la grande Intelligence a notre faible intelligence qui en derive. 
 J'avoue, au moins pour moi-meme, queje n'examine pas une simple fleur 
 sans etre etonne de la sagesse qui en a dispose les diverses parties, et sans 
 apercevoir dans le detail, ou dans I'ensemble, le texte de meditations 
 les plus profondes." — Voucher. 
 
 " Je crois que la principale utillte que Ton doit retlrer de cette etude, 
 se trouve dans les gouts simples qu'elle Inspire a ceux qui la cultlvent. 
 Le jeune liomnie qui s'y applique avec ardeur, se derobe par son moyen 
 aux passions turbulentes du premier age, et fortifie sans cesse sa sante par 
 des exercises agreables." — Vaucher. 
 
47 
 
 ALGM FILIFORMES. 
 
 Fai^iily SIPHONEiE. 
 
 Characters. Algae composed of a continuous branched and 
 cylindrical cell Eeproductlve organs external. 
 
 Genus VAUCHERIA D. C. 
 
 Char. Frond here and there occasionally injlated. Repro- 
 ductive organs of two kinds, consisting of capsules and 
 anthercB or horns, lateral or terminal. 
 Vaucheria D. C. in Yaucli. Couf. ; Lyngb. Q6. t. 19. 23. ; 
 E. B. 1766. 933.; Flor. Dan. t. 1724. 1727.; Grcv. 
 A1q:» Brit. t. 19. JScfos2)erma Yaucli. Conf. t. 2, 3. ; 
 UnVr in N. A. N. C. xiii. p. 789. 140.; Conf. Sp. 
 Dilhv, t. 15, 16. 47. 74. 
 
 Op all the freshwater AlycB none are more interesting or 
 more curious than those which we are about to describe. It 
 was from a knowledge of the reproduction of this genus, which 
 was first clearly made known by Vaucher, in his excellent 
 work on the Alyce, the only monograph at the period in ex- 
 istence devoted exclusively to the consideration of the fresh- 
 water division of the tribe, that naturalists were led to entertain 
 the notion of sexes in this class of plants, a notion which 
 even now it is by no means easy in all cases to discard. 
 
 The Vaucheria are first described in this work, because 
 amongst the freshwater Algce they seem to stand alone, exhi- 
 biting no distinct relation to any other genus of that division 
 of the Alyce, although to the genera Codinm and Bryopsis, 
 amongst the marine species, they manifest a close affinity. 
 
 The organs of reproduction of the Vaucherioi are of two 
 kinds, being composed of capsular bodies, and of filaments. 
 
48 SIPHONED. 
 
 placed close to the capsules, which have been termed anther, 
 fiom the analogy which they present to the anthers of Pha- 
 nerogamic plants in situation, and, as some even consider, in 
 function. 
 
 The nature of the large oval or si^herical bodies, one of 
 which is contained in each capsule invested with its proper 
 membrane or membranes, does not seem to be satisfactorily 
 determined. Vaucher states in his " Histoire," that he has 
 traced their growth and developcment into perfect plants ; but 
 the observation does not ajipear to have been placed beyond 
 question by the additional testimony of other witnesses. 
 
 With respect to what Vaucher terms the horn, from its 
 curved appearance, although he would seem to have entertained 
 but little doubt that it really performed the office which he 
 assigned to it, viz., that of an anther, nevertheless, he was 
 unable to bring forward any direct proof that it did so ; and 
 this he appears himself to have acknowledged and regretted, 
 as wall be seen from the following passage : — " Nevertheless, 
 I am not sufficiently certain of the functions to wdiich the 
 horn which accompanies the seeds is applied. It is in truth 
 constantly placed in the neighbourhood of the grains, and it 
 is seen, especially in Vaucheria {Ectosperma Vauch.) ovoidea 
 to shed its powder ; that is incontestable ; still I have 
 always desired some direct evidence which should convince 
 me of the use of this horn." 
 
 That the horn has an office to fulfil in relation to the spores 
 or sporangia, none can doubt who consider its almost con- 
 stant presence, the situation which it occupies with reference 
 to them, the shedding of its granular contents, and the 
 subsequent changes which it undergoes indicative of its 
 having performed the duty allotted to it. T\niat the exact 
 nature of this duty is, cannot as yet be determined, although 
 every additional observation which has been made tends to 
 strengthen and confirm the view of its function adopted by 
 Vaucher, viz. that it is the organ by which fertilization is 
 effected. The truth of this statement will be evident from 
 the following remarks : — 
 
 In page 17. of Vaucher's " Histoire des Conferves d'Eau 
 
VAUCHERIA. 49 
 
 doupe," the following observations occur. Alluding to the 
 horns, Vaucher observes — " At first they are straight and 
 opaque, and consequently contain the green fecundating 
 matter; gradually they incline towards the grain, and surround 
 it, so that they rest upon it to shed their powder. When 
 the seed is separated, they are empty, and assume a spiral 
 form ; and what confirms me still more in the opinion, that 
 the horns fulfil the functions of stamina is, that all the Ec- 
 tosperms which are provided with them have no other en- 
 largement, and that, on the contrary, those which have other 
 enlargements are altogether destitute of the horns." 
 
 If the horns approach the seeds in some cases, the con- 
 verse is true in others ; and the propriety of this will be 
 evident when we consider the position of the horns with 
 reference to the grains or germs in some species. In Vau' 
 cheria gemmata, the germs which are furnished with pe- 
 duncles approach the horns, in contact with which they 
 remain for some hours, and then gradually they raise them- 
 selves from it, and the peduncles which support them curve 
 backwards away from the horns. This gradual approach of 
 the grains to the horns, and their subsequent retraction from 
 them, strengthen the conclusion that this organ is necessary 
 to the grains. For Vaucher's assertion to be correct, that the 
 horns approach the grains in the case where there is but one 
 anther, situated midway between two spores, it would first 
 have to turn towards and reach the one spore, and then act 
 in like manner towards the other ; the improbability of which 
 is self-evident ; but, on the other hand, how simply are the 
 germs brought Avithin the influence of the horn by their ap- 
 proach to it on each side. 
 
 The " other enlargements " in which the horns ai-e absent, 
 referred to by Vaucher, I presume to be terminal enlarge- 
 ments of the threads, as in Vauchei^ia clavata, and which are 
 altogether of a different nature from the capsular bodies de- 
 scribed. Oval inflations of the filaments do also occur occa- 
 sionally : the presence of these, however, is by no means 
 constant, and they do not seem to be in any way connected 
 with reproduction. 
 
 E 
 
50 SIPHONED. 
 
 Additional evidence in favour of the influence exerted by 
 the horns consists in the fact of the capsules or seed-vessels 
 being either perforated or prolonged into a short tube, just at 
 the place where it comes in contact with the horn. This apertiu-e 
 may fairly be presumed to be intended to facilitate the admission 
 to the sjiores of the granular matter discharged by the horns. 
 
 Allusion has already been made in the Introduction to the 
 powers which many Confervce possess of resisting Ioav degrees 
 of temperature. The spores of the different species of 
 'Vauchej'icB would appear to be endowed with this power to a 
 remarkable extent. " In spite of all my precautions, the 
 frost of winter reached the water of my vase, and my grains 
 became enveloped {engagees) in very thick ice. They remained 
 thus until the period of the thaw, that is to say, during 
 fifteen days, and when they reappeared, I believed them at 
 first to be too much injured to hope for any success ; but I 
 called to mind very opportunely the experiments of Spallan- 
 zani upon the different degrees of cold which seeds would 
 bear, without losing in consequence the faculty of germination ; 
 and well convinced that the Conferv(B exposed to the open 
 air had not been more fortunate than mine, I resolved not 
 to abandon my observations." The observations were con- 
 tinued ; and, as states the text, the grains germinated, to the 
 infinite delight of Vaucher, 
 
 This faculty of resisting cold is bestowed upon the Vau- 
 chericB and many Conferva, and especially upon their seeds, 
 with the evident design of guarding against the extinction of 
 the species, which would be almost certain to occur upon the 
 freezing up of the waters of the ditches in which they are 
 usually found. The power also which these plants, and es- 
 pecially their seeds, retain of sustaining high degrees of tem- 
 perature, is scarcely less remarkable, and is doubtless im- 
 parted to them with a similar provident intention. This 
 power in the case of the spores is to be explained by reference 
 to the compact capsule which surrounds them, and which 
 prevents the evaporation of the interior moisture. Another 
 precaution adopted by nature to guard still further against 
 the risk of the extermination of any species, is the fact 
 that very many Conferva (tlie Vmicherice included), and 
 
VAUCHERIA. 51 
 
 especially such species as Inhabit shallow and extended waters, 
 mature and shed their seeds prior to their drying up, and that 
 the special period of their doing this varies in a measure with 
 that of the exhaustion of the water. 
 
 Further research will doubtless disclose many other species 
 in addition to those described to be inhabitants of the 
 fresh waters of Great Britain. Few species of the genus 
 Vaucheria dwell in the sea. They bear, however, a close 
 analogy to the marine genera Bryojjsis, Codium, and especially 
 Ectocarpus. M. Decaisne places the Vaucheria in his class 
 AplosporecBy a class in which the Batrachospermece find a place. 
 They are much more nearly related to his Sunsjjores, than 
 to the family of Batrachosperms. 
 
 a. Vesicles lateral, solitary. 
 1. Vaucheria dichotoma Ag.* 
 Plate IV. Fig. 1. 
 
 Char. " Frond setaceous, dichotomous, fastigiate. Vesicles 
 solitary, globose, sessile, ^^ — Grev. 
 Hooker's Brit. Flor. vol. ii. p. 319. ; Conf. dichotoma, Eng- 
 lish Botany, t. 932. ; Harvey's Manual of British Alga3, 
 p. 147. ; Berkeley's Gleanings ; Dilhvyn's British Con- 
 ferva?, t. 65. 
 Hab. " In jjonds and ditches ; frequent ; annual ; spring 
 and summer." 
 
 " Fronds setaceous, a foot or more in length, dichoto- 
 mously branched, forming wide strata at the bottom of jjools, 
 and frequently fiUing them ; colour, a pale yellowish green, 
 and occasionally dark." — Harv. I much doubt whether this 
 is anything more than a condition of Vaucheria sessilis, the 
 capsule being of precisely the same form as in that species, and 
 upon undoubted specimens of Avhich it is by no means uncom- 
 mon to find solitary capsules. A yellowish or olive green is the 
 colour of all the species of the genus when aged and in seed. 
 
 * The abbreviation of the name of the individual affixed to the specific 
 denomination of any production does not necessarily imply more than the 
 fact, that the person thus alluded to was the first to plat^e that production 
 in the genus with which it is in this work described. 
 E 2 
 
52 SIPHONE^E. 
 
 2. Vaucheria Dillwynii Ag. 
 Plate IV. Fig. 3. 
 Char. Yvo\\(\Jlexuous, terrestrial. Vesicles sessile, globose, 
 Grev. Alg. Brit. p. 191. t. 19.; Hooker, Brit. Flor. p. 320. ; 
 Conf. frigida, Dillwyn's British Confervas, t. 10. ; Conf. 
 frigida Roth, Cat. Bot. 1. p. 166.; Harvey's Manual, p. 
 147.; Fl. Germ. 111. p. 491. Co??/! amjMhia Jibrillosa et 
 spongiosa, C. terrestris exilis Jihrillosa, Bay's Synopsis, p. 
 59. n. 7. 
 Hab. Cheshunt : A. H. H. Sussex : Mr. Jenner. 
 
 This species is by no means uncommon, forming patclies 
 of a bright green colour, on moist and clayey ground. This 
 Conferva, Mr. Dillwyn observes, is not unfrequently found 
 in turnip fields during the winter and early months of spring, 
 particularly in a northern exposure, and on a cold soil. The 
 patches vary in size, but are usually two or three inches in 
 extent, adhering but slightly to the soil, and consisting of 
 loose, unconnected filaments. The form of the capsules, 
 which are rarely pedunculated, will at once distinguish this 
 from all other species which have hitherto been described. 
 
 3. Vaucheria repens Hass. 
 
 Plate VI. Fig. 7. 
 
 Char. Frond terrestrial. Capsules avicular, or in the form of 
 a bird's head. 
 
 Hassall, in Annals of Natural History, vol. xi. p. 430. 
 
 Hab. Growing on a footpath near Royston, Essex, Feb. 
 21st, 1843. 
 
 This forms patches upon the moist earth, like the preceding, 
 from which it is not to be distinguished without the aid of a 
 lens. The form of the capsules, as seen in the figures, is very 
 different from that of Vaucheria Dillwynii, and by it the 
 species may at once be known. I have only once met 
 with it. 
 
VAUCIIERIA. 53 
 
 4, Vaucheria hamata Vaucli. 
 
 Plate V. Fig. 1. 
 
 Char. Capsules ovate, pedunculate, overhanrjing the in- 
 curved anther. 
 Ectosperma hamata Vaiicli. Hist, des Conf. d'Eau douce, p. 
 26. pi. ii. fig. 2. ; Ilassall, in Annals of Nat. Hist. vol. xi. 
 p. 439. 
 Hah. Vicinity of Cheshuut ; not uncommon. 
 
 This species is very distinct, and first occurred to me at 
 Cheshunt, in a ditch half filled with water, in company with 
 Vaucheria geminata. " It differs from all the others by the 
 manner in Avhich it carries its grains. The peduncles which 
 sustain them are much elongated, and they bear at their ex- 
 tremity two little threads : the one is recurved and receives 
 the anther, the other is shorter and straighter, and carries the 
 grain." — Vaucher. 
 
 5. Vaucheria terrestris Vauch. 
 Plate V. Fig. 2. 
 
 Char. Frond irregular, terrestrial. Capsules pedunculated, 
 
 resting almost directly on the recurved anther. 
 Ectosperma terrestris Vaucher, Hist, des Conf. p. 27. pi. ii. ; 
 
 Grev. Alg. Brit. p. 191. ; Hook. Br. Fl. p. 320. ; Berk. 
 
 Glean. Alg. t. 9. 
 Hah. Cheshunt : A. H. H. Shady places, frequent, 
 
 Sussex : Mr. Jcnner. 
 
 This Vaucheria, like V. Dilhvynii and V. repens, is also 
 terrestrial, and like them also forms patches on damp and 
 clayey soil, Avhich frequently present a bristled appearance, 
 occasioned by a number of short and vertical branches, wliich 
 arise from the horizontal creeping fibres. 
 
 The species bears some resemblance to the preceding ; the 
 peduncle is larger, coarser, and not so forked as in it, and the 
 j: 3 
 
54 SIPHONED. 
 
 seed-vessel, which is of smaller size, rests almost immediately 
 on the incurved anther. 
 
 Found in fructification, according to Vaucher, in the 
 autumn ; my specimens were obtained in a hedge at 
 Cheshunt in March, and were also in fructification. 
 
 b. Vesicles lateral, sessile, geminate. 
 
 6. Vaucheeia aversa Hass. 
 
 Plate VI. Fig. 5. 
 
 Char. Capsules usually in pairs, and in the form of a 
 bird's head, ivith the beaks averted from each other. Spo- 
 rangia circular, not entirely filling the cavity of the capsule. 
 Hassall, in Annals of Nat. Hist. vol. xi. p. 429. 
 Hab. Vicinity of Cheshunt. 
 
 I have now met with this species repeatedly ; it is one of 
 the best marked and most peculiar of the genus, the 
 beaks of the capsules being turned in opposite directions at 
 once, distinguish it from all other known species, in which, 
 when the vesicles are in pairs, they are directed towards 
 each other. This averted position of the capsules renders 
 the existence of a distinct horn or anther essential for each. 
 In the form of the seed-vessels, and in the circumstance of the 
 sporangia not filling the entire cavity, the species resembles 
 Vaucheria ornithocephala. 
 
 7. Vaucheria ornithocephala Ag. 
 
 Plate VI. Fig. 4. 
 
 Char. " Vesicles binate or quaternate, ivith a short beak, and 
 pellucid border, upon short, straight peduncles.'''' — Harv. 
 
 Grev. Alg. Brit. p. 193. ; Hooker, Brit.Flor. p. 320. ; Conf. 
 vesicata Dillw. Brit. Conf. t. 74. ; Harv. Manual Brit. 
 Alga3, p. 148. 
 
VAUCHERIA. 55 
 
 Hab. Near Bristol : JV. W. Young. About Edinburgh : Dr. 
 Grcville. 
 
 This species would appear to be one of the rarest of the 
 genus. I have myself never encountered it. 
 
 8. Vaucheria sessilis Vauch. 
 Plate IV. Fig. 2. 
 Char. Capsules jjyriform, large, sessile. 
 Ectosperma sessilis Vauch. Hist, des Conf. d'Eau douce, 
 Grev. Alga) Brit. p. 192. ; Hook. Br. Fl. p. 320. ; Eng. 
 Bot. t. 1765. ; Harv. Manual, p. 148. 
 
 This is oue of tlie most abundant species of the genus. 
 Tlie vesicles are almost as often solitary as in pairs ; and in 
 this state I apprehend it constitutes the Vaucheria dichotoma 
 of writers. The spores are frequently noticed to be of a 
 reddish colour. This appearance is common to all the species 
 of the genus, and is probably the result of age, and also an 
 indication of the presence of azote. 
 
 c. Vesicles pedunculate, in pairs, lateral. 
 9. Vaucheria geminata Vauch. 
 Plate III. Fig. 1. 
 
 Char. Capsules situated on a divided peduncle, common to 
 hath. Anther intermediate. 
 Ectosperma geminata Vauch. Hist, des Conf. p. 29. pi. ii. 
 fig. 5. ; Grev. Alga3Brit. p. 193. t. 19 . ; Hook. Br. Fl. 
 p. 320. ; Eng. Bot. t. 1766. ; Harv. INIanual, p. 148. 
 
 The filaments of this species arc much finer than tliose of 
 any of the preceding ; the seed-vessels, too, are smaller, and 
 represent a sphere liollowed out on the inner side, or towards 
 the anther. The peduncle is common to both seed-vessels : 
 after ascending for some distance from the filament from 
 which it rises, it sends off laterally two branches, on each of 
 
 E 4 
 
56 SIPHONED. 
 
 which a capsule rests, the continuation of the peduncle forming 
 the anther. 
 
 Occasionally it happens that the capsules are sessile, and 
 the plant bears some resemblance to Vaucheria scssilis ; it 
 differs, however, in being altogether much smaller, and in the 
 form of the capsules. 
 
 It was first discovered in England by W. Borrer, Esq., as 
 far back as 1807. It is by no means uncommon throughout 
 England. 
 
 d. Capsules in clusters, lateral, pedunculate, 
 
 10. Vaucheria eacemosa Vauch. 
 
 Plate III. Fig. 2. 
 
 Char. Capsules usually four in number, placed upon a pe- 
 duncle common to all, ivhich terminates in a single anther. 
 
 Ectosperma racemosa Vauch. Hist, des Conf. d'Eau douce, 
 p. 32. pi. ii. fig. 8. ; Grev. Alg. Brit. p. 195. ; Harv. in 
 loc. cit. p. 149. 
 
 Hah. About Edinburgh : Dr. Greville. Vicinity of Ches- 
 hunt, not uncommon. 
 
 " This species is one of the most common, and is found iu 
 nearly all ditches, principally in the spring. It is loaded 
 with little bouquets manifest to the unassisted sight, and 
 which with the microscope seem to be formed of a common 
 peduncle, subdivided into pedicels, each of which carries on its 
 summit a spherical body, in every way resembling the grains 
 of other ectosperms, but nearly half as small again. In the 
 middle of this bouquet is the horn, which, without doubt, 
 performs the function of a male flower, and Avhicli is here 
 but a prolongation of the peduncle. The number of grains 
 varies from five to seven, but commonly four are met with." 
 — Vaucher. 
 
 It is this species which is most frequently infested with 
 the curious parasite, Cyclops lupula of jNIiiller, which occasions 
 the growth on the filaments of such extraordinary-looking 
 appendages, in the midst of which the parasite resides. 
 
VAUCHERIA. 57 
 
 A second racemose species is described by Yaucber, but 
 tliis has not as yet been found in England ; it differs in several 
 essential respects from Vaucheria racemosa. The grains, like 
 those of V. racemosa, are all supported on a connnon peduncle 
 furnished with pedicels ; but they are much larger and of a 
 different form, and each, moreover, is supplied with a distinct 
 anther. 
 
 e. Capsules in jmirs, terminal. 
 
 11. Vaucheria otoidea Vauch. 
 
 Plate V. Fig. 3. 
 
 Char. Capsules in terminal pairs, a recurved anther being 
 placed between each pair. 
 
 Ectosperma ovoidca Vauch. Hist. p. 30. ; Spec. Plant. 
 ~ p. 1634.; Flor. Aug. p. 954.; Flor. Scot. ^. 979.; 
 
 Withering, iv. p. 129. ; Koth. Flor. Germ. p. 1. No. 7. ; 
 
 Cat. Bot. i. p. 16., ii. p. 192.; Conf. amphibia Jibrillosa 
 
 et sp)ongiosa Dill. Hist. Muse. p. 22. t. 4. fig. 17. B. 
 
 and C. B. ramis elongatis ; Grev. Alg. Brit. p. 194.; 
 
 Harv. in Plook. Br. Flor. p. 320.; Conf. amphibia 
 
 Dillw. t. 41.; Conf. furcata B. Fl. Ang. p. 592.; 
 
 Withering, iv. p. 128.; Ceramium caspitosum Both. 
 
 Flor. Germ. iii. pp. 1. 475.; Cat. Bot. i. p. 154. ii. 
 
 p. 186.; Conf palusti'is Jilamentis brevioribus et crassior- 
 
 ibus Bay, Syn. p. 447. 
 
 " Amongst flowering plants we find several instances of 
 striking varieties produced by the more or less watery 
 situation in which individuals chance to grow ; and perhaps 
 no botanist would acknowledge the two most opposite 
 varieties of Myosotis scorjyioides, or Lotus corniculatus, to 
 be the same species, Avithout an opportmiity of tracing them 
 through their several gradations. The same may be said of 
 the present plant, which has hitherto formed two species, and 
 it is only after a careful examination that I have united 
 them as one." 
 
58 SIPHONEiE, 
 
 " On the edges of ditches, and in similar situations, it 
 frequently occurs in masses so densely matted, as to hold 
 water like a sponge, with its surface beset by erect branches, 
 which give it a very bristly appearance. In this state it is 
 well known to botanists as the C. amphibia of all modern 
 authors. Its hue is a bright green, becoming ash-coloured 
 with age. The root I have not been able to discover, and 
 the entangled mode of its growth renders it impossible to 
 ascertain the length of the filaments. These are repeatedly 
 divided with distinct patent branches, which, as before 
 mentioned, when the plant grows in shallow water, so that 
 some of them are exposed to the air, send out patent ramuli 
 of a stunted growth, from being out of their proper element, 
 which by their erectness give the plant its bristly appearance; 
 yet, at the same time, if whilst in this state the waters rise 
 so as to overflow the plant, their length is gradually increased, 
 and losing their erect position, they yield to the current, 
 and become the Ceramium ccespitosum of Roth ; and after 
 haviug thus clianged, if by the subsidence of the waters the 
 surface is again exposed to the air, the filaments, of course 
 disposed horizontally, give the plant a bi'istly appearance by 
 again throwing out erect patent ramuli." — Dilhc. 
 
 The above description of ISIr. Dillwyn, is applicable, I 
 suspect, not merely to Vaucheria ovoidea, but to, perhaps, 
 nearly all the VaiichericB which dwell in shallow water. V. 
 ovoidea delights, according to Vaucher, in the purest water, 
 that of fountains for example ; and it is certainly not so 
 common as might be supposed to be, if it were the only 
 species of the genus which assumed a ca3spitose character ; 
 for out of the many hundred examples Avhich I have examined, 
 I have never yet been so fortunate as to procure the plant in 
 seed. On the young, dense, and spongy tufts it is rare to 
 find capsules of any kind. 
 
 M. Decaisne describes movements of the capsular body of 
 this species altogether analogous to those of V. clavafa, detailed 
 in the Introduction. 
 
VAUCHERIA. 59 
 
 f. Capsules numerous, lateral, on separate peduncles. 
 
 12. Vaucheria poltsperma Hass. 
 
 Plate VI. Fig. 6. 
 
 Char. Frond minute. Capsules separate, in the form of 
 a bird's head, pedunculated, varying in number from 
 three to five, but usually there are but three sporangia, 
 not entirely filling the cavity of the seed-vessels or cap- 
 sules. 
 Hassall, in Annals of Nat. Hist. vol. xi. p. 429. 
 Hab. Vicinity of Cheshunt. 
 
 This species, which is by no means uncommon, may be dis- 
 tinguished from all others known to me by the fineness of 
 its filaments, which are not half so large as those of our other 
 British species, no less than by the form and arrangement of 
 the seed vessels. These are slightly pedunculate, varying in 
 number from three to five, but iisually there are but three, 
 the apices or beaks of which are neither turned towards or 
 averted from each other, but are all directed one way. The 
 resemblance which the capsules bear to a bu'd's head when 
 viewed sideways is very remarkable, and this resemblance is 
 rendered still more striking by the fact of the circular s^Doran- 
 gium occupying only the central portion of each, and which 
 therefore represents the eye of the bird. 
 
 It is remarkable to observe that in this Vaucheria there 
 are no distinct horns or anthera), the base of each vesicle 
 before its complete formation appearing to represent the 
 anther. 
 
 g. Proper Capsules none, AnthercB none. 
 
 13. Vaucheria clavata Vauch. 
 
 Plate II. 
 
 Char. Frond avspitose, the extremities of the branches 
 clavatc. 
 
60 SIPHONEiE. 
 
 Ectosperma clavata Vauch. Hist, des Conf. d'Eau douce, p. 
 34. pi. iii. fig. 10. ; V. Ungeri, M, G. Tliuret, in Annales 
 des Sciences Naturelles ; Berk. Glean. Alg. t. 10.; 
 Harvey, in Manual, p. 149, 
 
 So far from agreeing with M. G. Thuret as to the pro- 
 priety of referring all other species of VauchericB to this one, 
 and constituting a single species of the whole under the 
 name of Vaucheria Ungeri, I am of opinion that V. clavata 
 itself ought not to be regarded as a distinct species, but 
 merely as a condition of almost any one of the numerous well- 
 defined species Avhich have been described. I am led to en- 
 tertain this opinion from having repeatedly observed that 
 the club-shaped extremities are present, terminating many 
 of the filaments of almost all the species which are now 
 recorded, and the distinctness of which cannot for a single 
 moment be doubted. True it is that very many specimens 
 covered with capsules do not present the club-form dilatations 
 of the filaments, and also that these latter are generally pi*esent 
 when the former are altogether wanting. But these facts 
 admit of a rational and interesting explanation, entirely con- 
 sistent with the view here expressed. The specimens of 
 VauchericB furnished with capsules, and those having them 
 not, but possessing the claviform filaments, are usually met 
 with under very different circumstances, the one for the 
 most part in still water, and the other in flowing, such as 
 streams and cascades, that is, the one set of specimens are 
 found in circumstances favourable for the developement of 
 capsules and anthera3, and for permitting the mutual in- 
 fluence, which these organs are supposed to exert on each 
 other, to take place ; and the other kind, or second set, are 
 encountered in localities most unfavourable for these purposes 
 and ends, and in which in many cases it would be impossible 
 for capsules to develope themselves, the filaments being con- 
 stantly washed and pressed upon by the force and weight of 
 the incumbent and flowing waters. This leads to a necessity 
 on the part of Nature, who is so fertile in resources in times 
 of diflftculty and danger, to adopt some other mode of repro- 
 
VAUCHERIA. 6 1 
 
 tluctlon for plants so circumstanced, and tlms cfFcctually to 
 guard against the extinction of the species — her great care. 
 This she beautifully and securely effects by ordaining that 
 the reproductive bodies should appear at the extremity of the 
 filaments, that is, in a situation where they are least or but 
 little exposed to the impetuosity of the stream or cascade 
 Avhich may roll over them. 
 
 Vaucher remarks of the species as follows : — "It is met 
 with in the pure and running waters of fouuiains and rivulets, 
 and it attaches itself to the wood and stones which there are 
 found, and upon which it forms tufts of a bright green. It 
 appears to be composed of tubes, which are more slender than 
 in the other species, and present likewise a more lustrous ap- 
 pearance ; it is soft and unctuous to the touch ; its extremities, 
 principally in winter, are for the most part terminated with 
 oval and not articulated masses, of wdiich mention is made 
 above. Their powder expands itself easily, especially when 
 one irritates them with a needle ; I have vainly sought for 
 the grains of the plant ; I have never been able to see them, 
 although the species is very common, and I have sought for 
 them for two successive years." 
 
 So far back as 1826, some interesting remarks were made 
 on this plant, or state of one, by M. Frank linger, which 
 may not be deemed uninteresting. They are taken from 
 Charlesworth's "Magazine of Natural History." 
 
 " I found," says M. Frank linger, " near Vienna in a 
 ditch containing some clear water, derived from the recent 
 melting of the snow, a Conferva, which, after cleansing from 
 the clay w^hich surrounded it, I deposited in a wine-glass 
 and placed in a window, Avhere I could observe without dis- 
 turbing it. This Avas on the 5tli of INIarch, 1826. . Two days 
 afterwards I noticed the production of a crowd of new ramuli, 
 several lines in height, and rising from the general mass like 
 a fine green miniature sward. On the 9th, these filaments 
 produced fructification in the form of a darker green globule 
 at their summits, by which I knew my plant to be the 
 Conferva dilatata, Cat. Bot. Eoth., or the Ectosperma clavata 
 of Vaucher. 
 
62 SIPHONED. 
 
 " As I continued my observations, I happened to look at 
 the surface of the water, and was not a little astonished to 
 find it covered, especially towards the side of the vase, with 
 minute globules, unequal both in colour and size. Many of 
 them swam freely about here and there, moving at their 
 option in one way or another, retiring and approaching one 
 another, gliding round globules that were motionless, stopping, 
 and again setting themselves in motion exactly like animated 
 beings. 
 
 " Conjecturing the identity of the green globules that pos- 
 sessed motion with those that had none, I immediately began 
 to examine whence these infusory animalcula derived their 
 origin, and what relation they bore to the green globules 
 and the fructification of the Conferva. 
 
 " The next day I perceived a great number of the globules 
 aggregated around the bubbles of air, disengaged from the 
 Conferva and floating at the surface. Some of them were 
 of a dark-green colour, and either round or elongated ; 
 others more transparent, tumid, and with one or two appen- 
 dages diverging from or at right angles with each other ; 
 these were e^ddently plants in a state of germination ; other 
 globules again were oval, very dark at one extremity, and 
 almost transparent at the other ; these swam about freely. 
 
 " Within the space of an hour I succeeded in tracing not 
 only the diminution of vitality and death of the Infusoria, 
 but also the subsequent developement of the dead animals into 
 germinating plants, in such a manner as to establish the 
 truth of the fact. But on the 12th of ]March, I had the 
 pleasure of ascertaining distinctly the origin of these minute 
 bodies. I undertook to observe without interruption one of 
 the tubercles of fructification, which I have already mentioned 
 as terminating the filaments, in order to discover Avhat became 
 of the green matter enclosed within it. I had observed it for 
 the space of half an hour when the following changes became 
 perceptible. 
 
 " The globule became gradually darker in its colour, and a 
 little transparent at its extremity: in the middle it was 
 evidently somewhat contracted, and had some traces of 
 
VAUCHERIA. 63 
 
 spontaneous motion. I could scarcely believe my eyes when 
 I perceived the contraction to become more decided, and a 
 cavity to be formed at the base. The contraction at length 
 divided the globule into two smaller globules, which moved 
 spontaneously towards the summit. As the developement 
 proceeded, the cavity and the uppermost globule became 
 enlarged, v/hile the inferior globule became diminished : the 
 latter at length disappeared, and the remaining large globule 
 escaped by a terminal orifice, ascending till it reached the 
 surface of the water. The whole of this process occupied 
 about thirty seconds ; but from subsequent observations it 
 may be stated generally to take up one minute." 
 
 M. Unger has, in his late work, verified the correctness of 
 the above observations in all essential particulars, and has 
 further proved that the motion of the spores is owing to 
 their surface being covered with vibratile ciliary organs, until 
 lately supposed to be eharacteristic of animal life. M. G. 
 Thuret has also more recently published an excellent memoir 
 on the formation and developement of the spores in Vaucheria 
 clavata. See Introduction. 
 
 " From the Constancy that is observed in the Number Figure Place 
 and Make of all the principal Parts ; and from the Variety in the less. 
 Man is always mending and altering his Works ; but Nature observes 
 the same Tenor, because her "Works are so perfect that there is no 
 place for Amendments; nothing that can be reprehended. The most 
 sagacious Men in so many Ages have not been able to find any Flaw in 
 these Divinely contrived and formed Machines, no Blot o?- B?-ro7' in this 
 great Volume of the World, as if anything had been an impeifcct Essay 
 at the first (to use the Bishop of Chester's AA^ords:) Nothing that can be 
 altered for the better ; notliing but if it were altered would be marred." 
 — Rays Wisdom of God. 
 
G4 THORE^.. 
 
 Fam. IL THOREiE. 
 
 Char. Main filaments solid, inarticulate, filiform, branched, 
 beset with short byssoidal, simple, or sometiriies ramose 
 and articulated fibrillce. Keproduction, according to 
 Kutzing, capsular, and springing from the fibrillce. 
 
 2. THOREA Bory. 
 
 Char. Same as those of the family. 
 
 Thorea Boiy, in Annales du Museum, xii. 126. t. 18. 
 (excel, sp. fig. 34.) Hydropih. Voy. Dupern. t. 24. fig. .3. 
 Agardh species, ii. 123. Po/j/coma Palis, in Journ. Bot. 
 108. p. 123. 
 
 " The Thorece appear to be related to the Batrachosperms, 
 with which M. Decandolle has confounded the species dis- 
 covered by M. Thore. They ought to follow them in a 
 classification. Like them, they present filaments of two 
 kinds, and they are, for the most part, slippery under the 
 fingers when one touches them ; but the filiform filaments 
 with which the plant is clothed are neither fasciculated nor 
 verticillate. "Whatever may be the fructification of the 
 Thorea, it can never be disposed like that of the Batracho- 
 sperms, which consists of naked buds aggregated and placed 
 in the centre of the verticilli, or wholly formed by the 
 branches. 
 
 " With the exception of the last species, which is a parasite 
 of certain lichens, the Thorea are aquatic plants. They 
 dwell in the coldest fountains, have an asjaect which is 
 peculiar, extreme flexibility, the property of uniting themselves 
 into mucous masses at the sources of waters, adhere strongly 
 to paper in drying, and take on the appearance of life when 
 they are replunged into the liquid in Avhich they have grown." 
 — Bory de St. Vincent. 
 
THOREA. 65 
 
 It might be supposed by some, from what has been said 
 in reference to the affinities of Thorea with the Batracho- 
 sperms, that it would naturally find a place amongst that 
 family, from which, however, it must be admitted, though 
 bearing certain resemblances to it, to be considerably es- 
 tranged by Its solid and inarticulate filaments. 
 
 This genus was constituted by Bory, in honour of Dr. There, 
 " Naturaliste de Dax, autcur d'une Chloris du departemcnt 
 des Landes," by whom one of the species of the genus was 
 discovered. 
 
 1. Thorea ramosissima. 
 
 Plate XVI. Figs. 3, 4. 
 
 Cha7\ Filaments very long and much branched. Colours, 
 when recent, blackish green, turning to violet in drying. 
 Bory, In Annales du Museum, voh xll. page 128. pi. 18. 
 fig. 1. Conf. hispida ramis vagis jiexuosis longissimis 
 obductis ramulis sctaceis, Drap. Ined. Conferva hispida 
 There, Mag. Encyc. t. vi. p. 398. Conferva hispida 
 There, Chloris, 442. Confervajlexuosajilamentis cylin- 
 draceis villosis subgclatinosis ; (3. aqua angustcR, JiJamentis 
 ramosis, violaceo subfuscis ; <y. pa7inensis, Jilamcnfis ramo- 
 sissiynis, violaceo griseis, Bory, 1. c. t. 11. p. 366. Batracho- 
 spermum hisjndum Cand. Syn. 12. ; Flor. Franc, ii. 
 p. 60. Th. Lchmanni Lyngb. t. 13.; Harvey in 
 Manual, page 120. 
 
 " The Thorea ramosissiina grows in the Adour, where it 
 adlieres to stones, to rocks, to branches, and to the stems of 
 trees which are found upon its margins. It is only to be 
 obtained there when the Avaters are low, in June and July. 
 It Is again met with In the Seine, between Neuilly and Paris, 
 attached to difterent bodies, and particularly to the bottom of 
 boats. 
 
 " From a little disc fixed upon the inundated bodies, proceed 
 certain filaments of the size of an ordinary thread, which 
 from their origin are ramified. The branches are always 
 F 
 
66 THOREiE. 
 
 sliorter than the filaments which give origin to them. The 
 first are always simple, the latter are covered with new 
 shoots, still shorter, up to near the extremities, these are 
 usually simple, so that the last branches are constantly 
 naked. 
 
 " The whole plant is covered with a fine and mucous down, 
 about half a line long or more. This down gives to the 
 branches the aj^pearance of little cylindrical stalks of the 
 size of a crow-quill. It is composed of simple " (rarely 
 branched) " threads in the form of cilia, in which the joints 
 are not apparent with a simple magnifying glass, but in 
 which they are distinguished when they are submitted to 
 a very strong lens. 
 
 " The branches of Thorea ramosissima are often many feet 
 in length, and float gently in the water, whose course they 
 folloAV. Their colour is an obscure and deep green. They 
 assume very frequently on paper a very elegant scarlet tint. 
 "N^^ien tliey are macerated in pure water, they soon acquire 
 the same tint, and they communicate it to every thing which 
 surrounds them. Pieces of flax, cotton, and silk contained 
 in the same vessels become dyed in a manner often very 
 intense. This circumstance has made me presume that some 
 use in the arts might be made for the fecula of Thorea ra- 
 mosissima.'''' 
 
 After detailing numerous chemical experiments, JSI. Bory 
 de St. Vincent concludes his descrij)tion of the species with 
 the following remarks : — "As to the use which might be 
 made of the fecula, that is easy ; painters have found its tint 
 more soft and more brilliant than that of violets obtained by 
 other processes; but I doubt whether this beautiful colour 
 would be very durable, by reason of the action which oxygen 
 necessarily exercises upon it, as one of the experiments we 
 have related shows." 
 
 The capsules, as seen in fig. 4. of plate xvi., which figure 
 is taken from Kiitzing's " Phycologia Generalis," would ap- 
 pear to bear a close resemblance to those of TrentepoJdia 
 pulchella, being, as in that species, small, pyriform, corymbose, 
 and subinvolucrate ; the secondary branches are occasionally. 
 
TIIOREA. 67 
 
 though rarely, again branched : this is also seen in Kiitzing's 
 figure. 
 
 Mr. Harvey, in his " Manual," writes, " Of this beautiful 
 plant, I have seen no British specimens. I introduce it on 
 the authority of a note in the late Mr. Templeton's MS., 
 whose well-known accuracy leaves no room to doubt his 
 correctness in this instance, though he has not preserved a 
 specimen in his * Herbarium.' " 
 
 " It may be (for ought I know, and as some Divines have thought) part 
 of our Business and Emjjioyment iu Eternity, to contemplate the AVorks 
 of God, and give him the Glory of his Wisdom, Power and Goodness, 
 manifested in the Creation of them. I am sure it is part of the Business 
 of a Sabbath day, and the Sabbath is a Type of that Eternal Best ; for 
 the Sabbath seems to have been first instituted for a Commemoration of 
 the Works of the Creation from which God is said to have rested upon 
 the Seventh Day. It is not likely that Eternal life shall be a torpid and 
 unactive State, or that it shall consist only in an uninterrupted and endless 
 Act of Love ; the other Faculties shall be employed as well as the AVill 
 in Actions suitable to, and perfective of their Nature ; especially the 
 Understanding, the Supreme Faculty of the Soul, Avhich chiefly difl^er- 
 enceth us from brute Beasts, and makes us capable of Virtue and Vice 
 of Rewards and Punishments, shall be busied and employed in contem- 
 plating the ~\^'orks of God and observing the Divine Ai-t and Wisdom 
 manifested in the Structure and Composition of them, and reflecting 
 upon their Great Architect the Praise and Glory due to Him, then shall 
 we clearly see to our great Satisfaction and Admiration the Ends and 
 Uses of these Things which here are either too subtle for us to penetrate 
 and discover, or remote and too inaccessible for us to come to a distinct 
 View of." — Ray. 
 
 P 2 
 
68 
 
 Fam. III. LEMANE/E. 
 
 3. LEMANIA Bortj. 
 
 Char. Frond attached, coriaceous, ramose, and cellular. Outer 
 cells small, polygonal, and Jirmly adherent ; interior 
 larger, more lax, splicerical, and empty. Sporules mo- 
 niliform, fasciculate, naked, arising from the inner vesicles, 
 and occupying the interior of the frond. 
 
 Lemania Bory, in Annales du IMuseum, vol. xii., also in 
 Diet, class, ix. 274. ; Agardh, in Act. Holm., 1814, t. 1. 
 species 1, 2. Nodularia Link, in Schrad. Jour., 1809, 
 p. 9. ; Lyngb. t. 29. Gongycladon I^ink, in Hort. 
 Physic. 6. Trichogonus Palis, in Jonr. Bot., 1808, 
 p. 123. (excel, sp.) Vertehraria Rouss, in Desv. Jour. 
 Bot. i. 143. Apona Adans. 13. PolyspcrmcB sp. Vauch. 
 t. 1. f. 3., t. 10. f. 1, 2. Conf sp. Dillw. t. 29. ; E. B. 
 1763. 
 
 The genus Lemania, like some other genera of freshwater 
 AlgcB, would appear to stand almost alone, exhibiting no 
 very exact relation with any other division of this tribe, and 
 the only plant to which it bears any definite resemblance 
 appears to be the Enteromorpha intestinalis, and this only in 
 its ramose habit, and in tlie cellular structure of the frond, 
 the rej)roduction in Lemania, though simple, being wholly 
 different from that of Enteromorpha. 
 
 Vaucher, in his description of his genus, Polyspcrma, of 
 which Conf. jiuviatilis formed the type, has not erred far from 
 the truth, and his generic name might, with propriety, 
 have been retained ; the chief mistake which he committed, 
 was in associating with Conf. jiuviatilis the Conferva glo- 
 merata, a plant in every way dissimilar to the former. 
 
 The branches of tlie fronds of the Lemanice, in their young- 
 state, are cylindrical; soon, however, they are seen to be- 
 come dilated at regular intervals. If one of these dilatations 
 
J.EMANIA. 69 
 
 be pressed between the fingers, their contents will be forced 
 out : on examining which, with the microscope, the observer 
 ■will be astonished to perceive that it is made up of a number 
 of beaded and plant-like bodies, which the inquirer would be 
 inclined, at first sight, to regard as the species in its young 
 state : this opinion, on further investigation, would be found 
 to be erroneous ; for if these tufted bodies be watched, and 
 kept in water for some time, the beads of the filaments will 
 soon be perceived to separate from each other, and each ul- 
 timately to become developed into a young plant resembling 
 that from which the seed was derived. The separation of 
 the sporules which compose the beaded threads likewise takes 
 place naturally within the frond, and it is by their develope- 
 ment that the dilatations of the stems, already referred to, 
 are produced, and by which an apparent resemblance to the 
 BatrachosjKrms is imparted to the plants of this genus. 
 
 Frequently, if these dilatations be examined with a lens, 
 numerous filaments may be observed issuing from them : 
 these are what Vaucher terms the young polyspcrms pro- 
 duced by the germination of the sporules, which are still 
 within the frond, and which developcment of them is or- 
 dained to take place in all cases to such an extent as to 
 occasion the rupture of the dilatations, and consequent separ- 
 ation of some of the cortical cells from each other ; thus, 
 apertures are created, through which the sporules may pass 
 out, a condition essential to the perpetuation of the species. 
 The force with which this developcment operates may be 
 appreciated when the cartilaginous nature of the frond is 
 considered. 
 
 It is only the middle and upper branches that are so 
 torulose, the lower being almost plain and cylindrical ; this 
 arising from the fact of the sporules having all escaped from 
 these, which are the oldest portions of the plant. 
 
 Bory's account of the structure of this genus appears 
 to contain some strange errors. " The Lemanioiy' he remarks, 
 " are articulated Conferva, whose contiguous joints are 
 united the one to the other by a solid interior filament, very 
 Avell represented by Vaillant (Bot. Paris, pi. iv. fig. 5.) in 
 
70 LEMANE^. 
 
 the figure wliich he has given of one of the species of our 
 genus." 
 
 " The buds of the Lemamce, sessile, naked, rounded, more 
 or less numerous, are situated at the points of junction of the 
 cells, which by their growth they render tumid. "\^Tien 
 these gemmules come to cover or deform the plants they 
 ajjpear to detach themselves from them ; they carry away 
 sometimes the joints wliich support them and elongate them- 
 selves to reproduce new Lemanice." 
 
 The above observations certainly do not apply to the 
 Lemania proj^er ; but Bory has included in the genus one 
 species at least i^Chara hatrachosperma, of which Batracho- 
 spermum atrum is a synonyme) which does not belong to 
 it, and on this, distorted and irregular-looking bodies do 
 occur, wliich I take to be analogous to the " glomerules " of 
 other Batracliosperms ; in this species as in others of the 
 same genus the interior tube referred to by Bory would be 
 found. 
 
 " The LemanicB are very rigid plants and with a peculiar 
 and corneous ai^pearance ; they crack under the teeth Avith a 
 taste Avliich reminds one of that of fish." 
 
 " M. Tliore of Dax first remarked, in the Confervafiuvia- 
 tilis of Limiasus, a fact which is verified in the other species of 
 our genus. The recent filaments of this Lemania, presented 
 towards the flame of a candle, explode and extinguish the 
 candle. This phenomenon does not take place in dried 
 specimens. It is owing to some gas shut up in the con- 
 nections of the joints, and which, put in expansion by the 
 heat, presses against the Avails and breaks them with an ex- 
 plosion. A remarkable movement of retraction is expe- 
 rienced in the fingers Avhich hold by the tAvo extremities the 
 filament experimented upon. As to the smell of the burnt 
 plant, although very peculiar, it cannot be compared to that of 
 animal substances submitted to the fire." 
 
 **I have not met Avith any Lemania in stagnant Avaters; 
 they groAV in quick Avaters. It is in the pure fountains, 
 large rivers, in very rapid riA'ulets, tliat they appear to de- 
 light. Many, moreover, flourish especially in those places 
 
LEMANIA. 7 1 
 
 where the current has the greatest force, such as in mill 
 sluices and the most impetuous falls of cascades. 
 
 " We have named our new genus Lemania. This name 
 comes from that of M. Lcman, a modest naturalist, not less 
 learned in botany than in the other branches of science." — 
 Bory. 
 
 Kiitzing, in liis " Phycologia Generalis," appears to have 
 studied this genus closely ; he there gives a beautiful, elabo- 
 rate, and accurate drawing of Lemania torulosa, from which 
 the figure of that species given in this work is chiefly derived. 
 
 1. Lemania torulosa Ag. 
 
 Plate VII. 
 
 Char. Frond nearly simple, incurved. Inflations of the stem 
 large, approxijnate. 
 
 Lemania incurvata, filamentis simplicibics, iiicurvatis, arti- 
 culis in centra turgidis, Bory, Annalcs du Musce, vol. xii. 
 p. 181. pi. xxi. fig. 1. Chantransia (tondosa) virescente- 
 nigresce7is, filamentis suhsimplicihus, articulis ovatis, 
 medio tumidis, Cand. Syn. 10. Chantransie en colliers, 
 Cand. Flor. fr. 2. p. 50. Co?iferva {tondosa) filamentis 
 filiformibus, torulosis ; genicidis contractis, anmdarihus ; 
 articulis ovalihus, infiatis^ Roth. Cat. Bot. 1. 200.; Fl. 
 German, iii. 527. Conferva {torulosa') filis toi'idosis, 
 simplicibus, continuis, filiformibus. Sec, Roth. Cat. Bot. 
 iii. 250. Cojifcrva {verrucosa) anomalacca, incurva, no- 
 dis eminentibus, approximatis, verrucosis, Draparn. MS. 
 ined. Conferva {fiuviatilis) filamentis simplicibus, seti- 
 formibus ; gejiicidis crassioribus, angulatis, Syst. Nat. 
 xiii. 11. 1392. Conferva fiuviatilis var. a, Encyc. Met. 
 Die. No. 12. (The synonyme of Vaillant ought to be 
 excluded as also that in the " Flore Fran^aise." — Bory.) 
 Conferva nodosa var. a, Lam. Flor. fr. 1278. ix. ' Con- 
 ferva fiuviatilis nodosa, fucum emulaiis. Dill. ]Musc. 
 fig. 48. t. vii. Lemania torulosa, Ag. Spec. ii. }). 0. 
 Conferva fiuviatilis var. tondosa, Englit^h Botany, t. 
 
72 LEMANEiE. 
 
 1763. ; Hook. Brit. Flora, ii. p. 322. ; Harvey, in Manual, 
 p. 119. 
 Hah. Mountain streams near Ludlow : Dillenius, Angle- 
 sea : Rev. H. Davies. 
 
 " It is now more than ten years since I observed, for the 
 first tune, this species, and I have named it after the very 
 peculiar form and remarkable curvature of its filaments, Le- 
 mania incurvata. I believe that so very characteristic a 
 name ought to be maintained; that wliich other botanists 
 have since given to this plant applies equally to two orders 
 of Confervce. 
 
 " The Lemania incurvata abounds in certain rivers ; I have 
 above all observed it in the Dordogiie, near the little town of 
 Sainte Foix. The fishermen bring it up from the bottom of 
 the river in their large nets. It has been confounded with 
 the following species, even by Linnceus himself; the figures 
 47 and 48, given by Dillenius, and that of Vaillant, referred 
 to alike indifferently by theu' authors, prove this. 
 
 " From a little horny disc, fixed to the hard bodies wliich 
 support it, arise from six to thirty filaments, frojn one inch 
 to two inches and a half in length, curved in one direction, 
 perhaps by the continual action of the current, to wliich their 
 rigidity opposes itself in vain. Then* colour is of a brownish 
 or reddish green, obscure or livid. They acquire in diameter 
 the greatest dimensions of all the Conferva. 
 
 " The joints are ovoid and thinned [amincies) at their point 
 of contact, while, in the following species, the contrary is 
 always observed. The Lemania incurvata Is moreover shorter 
 and thicker, and the filaments but rarely branched." — Bory. 
 
 2. Lemania fluviatilis Ag. 
 Char. Frond ramose. Inflations suhdista7it, oblong. 
 
 Lemania {corallina) Jilamentis subsijnplicibus, articulis oh~ 
 longis, extremitatibusturgidis, vol.xii. pl.xxi. fig. 2.; Bory, 
 in Annales du IMusee. Chantransia {Jluviatilis) viridi- 
 nigrescens ; Jilamentis subdivisis, cartilagineis ; articulis 
 teretibtis, genicidis tumidis, Cand. Syn. 10. Chantransic 
 
LEMANIA. 73 
 
 JluviatUe Cand. Flor. fr. 2. 50. Polysperma Jluviatllis 
 Vauch. Conf. p. 99. PI. 1. fig. 3. ct pi. x. fig. 1, 2, 3. 
 Conferva {Jluviatilis) Jilis suhramosis, sctaceis, nodosis, 
 geniculatis ; gcniculis torulosis, angulatis, §"c., Rotli. Cat. 
 Bot. iii. 304. Conferva jluviatilis filamcntis setaceis, 
 nodosis ; gcniculis elevatis, brevibus, articulis ohlongis, 
 cylindraccis, Eotli. Cat. Bot. i. 201.; Fl. German, 
 iii. 528. Conferva Jluviatilis var. /3, Encyc. Met. Die. 
 No. 12.; Thore, Chloris, 441. Coiiferve rameuse var. 
 ^, Lam. Flor. fo. 1278. ix. Corferva {Jluviatilis) Jilis 
 simplicibus, setiformibus, rectis, gcniculis crassioribus, an- 
 gulatis, Lin. Sp. 1635. Conf crva Jluviatilis, luhrica, se- 
 tosa, equiseti facie. Dill. Muse. viii. f. 47. Corallina 
 Jluviatilis non ramosa, Vaill. Paris, p. 40. t. iv. fig. 5. 
 Nodularia Jluviatilis Lyug. t. 29. Lemania Jluviatilis 
 Kiitzing, Phycologia Generalis, p. 322. ; Dillw. Brit. 
 Conf. PI. ; Hooker, Brit. Flor. ii. p. 322. Conf Jluvia- 
 tilis, English Botany, t. 17G6. Lemania Jluviatilis 
 Harvey, in Manual, p. 119. 
 Hab. In the Winterbourne Stream, Le^Yes : TV. Borrer, 
 Esq. In the stream at Hamsell, and at the Waterfall 
 at Harrison's Rocks in abundance : Mr. Jcnncr. Com- 
 mon in rapid streams about Aberdeen : Dr. Dickie. 
 Frequent in Ireland : Mr. Moore, 
 
 " The name of Jluviatilis, adopted after Dillenius by 
 authors, does not well apply to a plant much less frequent 
 in rivers than any one of its congeners. The name, borrowed 
 from Sebastian Vaillant, better designates our Lemania, and 
 gives a very just idea of its bearing. 
 
 " The Lemania corallina is one of the most common of 
 Conferva ; it is frequently found attached to stones, and upon 
 stakes that are always covered with water, near mill-dams, 
 or against the sides of their channels. I have seen fiills which 
 were quite covered ; the more rapid the current the more 
 the Lemania prospered. It becomes sometimes more than 
 half a foot in length, and of a considerable diameter. The 
 plant languishes or dies when any cu'cumstance renders the 
 water in which it lias grown stagnant. 
 
74 LEMANE^. 
 
 " From a cartilaginous disc, strongly applied to foreign 
 bodies, proceed a great number of close filaments, elastic, of 
 a brownish green colour, and a little curved at the base ; 
 but they become more pale and straight in the remainder of 
 their length. These filaments are ordinarily from four to 
 seven inches in length. Some are entirely simple, the others 
 throw out here and there branches, or divide towards the 
 middle of their length. 
 
 " The internodes are oblong, from a line to a line and a 
 half, cylindrical, and inflated at their points of contact. Their 
 divisions are often but httle apparent, and disappear towards 
 the base of the filaments, which appear continuous, cylin- 
 drical, and equal in diameter to a strong horse-hair. 
 
 " The surface of the filaments in old age is encrusted in 
 such a manner as not to become recognisable either by its 
 colour which changes, or by the destruction of the internodes, 
 which become confused and disappear." — Bory. 
 
 " I have seen this siJecies growing near the mouth of the 
 Don, very luxuriantly, where it must have been exposed to 
 the action of salt or very brackish water." — Dr. Dickie 
 in lit. 
 
 " Let us tben cousidei- tlie Works of God, and observe the Operations 
 of liis Hands ; Let us take notice of, and admire his infinite Wisdom and 
 Goodness in the Formation of them : No Creature in this sublunary 
 World is capable of so doing, besides INIan, and yet we are deficient 
 herein : We content ourselves with the Knowledge of the Tongues, or a 
 little Skill in Philology, or History perhaps, and Antiquity, and neglect 
 that which to me seems more material, I mean, Natural History and the 
 Works of the Creation : I do not discommend or derogate from those 
 other Studies : I should betray mine own Ignorance and Weakness should 
 I do so 5 I only wish they might not altogether justle out, and exclude 
 this. I wish that this might be brought in fashion among us ; I wish 
 Men would be so equal and civil, as not to disparage, deride and vilifie 
 those Studies which themselves skill not of, or are not conversant in ; 
 no Knowledge can be more j^leasant than this, none that doth so satisfie 
 and feed the Soul ; in comparison whereto that of "^Vords and Phrases 
 seem to me insipid and jejune." — Ray. 
 
75 
 
 Fam. IY. CALLITHAMNEiE. 
 
 4. TRENTEPHOLIA Ag. 
 
 Char. Frond affixed, ramose, articulated. Cells in single 
 series. Fructification corymbose, involucrate, and cap- 
 sular. 
 
 *' Except for its freshwater habitat this genus does not 
 differ from the preceding section of Callithamnion, which in 
 the ' Brit. Flora' I ventured to unite to it. At INIrs. Griffith's 
 instance I now give up this point, but must still observe 
 that Cal. Daviesii and T. indcliella, Avhen the latter is well- 
 coloured, are scarcely distinguishable under the microscope," 
 — Harvey. 
 
 1. TRENTErOHLIA PULCHELLA Ag. 
 
 Plate VIII. Fig. 2. 
 
 Char. Frond jKirasitic, tufted, hlood-red, much branched. 
 Filaments equal, apices obtuse. Articulations four times 
 as long as broad. Capsules pedunculate, in clusters, and 
 ovoid. 
 C. clmlybea Roth, Cat. Bot. iii. p. 286. tab. 8. fig. 2. C. 
 chalybca Dillw. Brit. Conf. t. 91. Conf corymbifcra, 
 E. B. t. 1996. and t. 2585. ; Harvey in Hooker's Brit. 
 Flora, p. 382. ; Harvey in Manual, p. 118. 
 
 Hab. On flints in Winterbournc Stream at Lewes, Sus- 
 sex : W. Borrer, Esq. On sandstones in a spring at 
 Ladsworth, near Midhurst, Sussex : Mr. Jenner. Clon- 
 mel : Dr. Allman. Hill of Fare, Aberdeenshire : Dr. 
 Dickie. Frequent in streams in Ireland : Mr. Moore. 
 
 " Professor Mertens first discovered the present delicate 
 species in the neighbourhood of Bremen, and communicated 
 it to Dr. Roth, who has puljlished it with a good figure in 
 the third volume of jiis ' Catalecta Botanicn.' Mr. Borrer 
 
76 CALLITHAMNE^. 
 
 has since added it to the British flora, having found it at 
 Winterbourne Stream at Lewes, Sussex ; and to him and 
 ]\Ir. Turner I am indebted for the sjDecimen here figured. 
 It grows on flint stones in Httle tufts about a quarter of an 
 inch in length, and of a bkiish green colour, glossy when 
 dry. The filaments, which are repeatedly branched, are 
 erect, straight, of equal height, and very flaccid and slender 
 throughout. The branches are placed at uncertain, gene- 
 rally considerable distances, from each other, and issue from 
 the stem so as to produce an obtuse angle, but immediately 
 curve inwards, and then rise in a more or less uj^right direc- 
 tion ; their disposition is far from regular, but they are fre- 
 quently disposed on opposite sides in alternate parcels of 
 two or three. The ramuli are always placed nearer to each 
 other than the main branches, and I have frequently ob- 
 served more than one proceeding from the top of the same 
 joint ; they are blunt at their apices ; the dissepiments are 
 readily observable with a microscojje, and divide the filaments 
 into perfectly cylindrical joints, of which the length is gene- 
 rally from four to six times greater than the diameter." — 
 Dllho. 
 
 To the above very accurate description of a most beautifid 
 production, it is necessary to add but very few words. The 
 single species of the genus Trentepolilia^ like those of the 
 two preceding genera, seem to find pleasure in pure and 
 running waters, attaching itself to any substance favourably 
 placed in the current of the stream, and to Avhich it can 
 firmly adhere. When in health the plant is of a blood-red 
 colour, a colour which, in decomposition, it readily imparts 
 to whatever it may be in contact Avith. This colour, how- 
 ever, is observed to change either by age or habitat, or 
 some other circumstance connected with its place of growth, 
 to a bluish grey, in wliich state it constitutes the Conferva 
 chalyhca of Dr. Roth and ISIr. Dillwyn. No diflerence can 
 be detected between the filaments of the two states, which 
 may therefore be concluded to be merely conditions of the 
 same Alga. The fructification, which adds much to the 
 beauty and elegance of the plant, is by no means rare. 
 
77 
 
 Fam. V. CHARACEtE. 
 
 Char. Stem dichotomoiis and jointed ; each joint composed 
 either as in Nitclla of a single cell or tube, or as in Chara 
 of a single cell surrounded by other smaller contiguous cells, 
 which take a spiral direction ; each articulation more- 
 over is suj'jnoujitcd by a variable number of branches three 
 or four times jointed, tvhich are arranged in the form 
 of a verticillum or whorl, and at the joints of which the 
 reproductive organs «re situated: these are of two kinds, 
 consisting of nucules and globules. Circulation sjnral, and 
 distinct in each cell. 
 
 Following the example of those more recent Algologists 
 who consider the Characca as Alga, I give this order a pro- 
 minent place amongst the British freshwater Algce, a position 
 to which they are well entitled, both on the ground of their 
 greater comparative complexity of structure, and of the high 
 interest attached to certain phenomena connected with their 
 history. 
 
 The phenomena more particularly alluded to in the pre- 
 ceding paragraph are twofold ; the first having reference 
 to the circulation in the cells of which the diiFerent spe- 
 cies of this order are composed, and the second to the ex- 
 istence of spermatozoa in the globules or male blossoms. 
 These phenomena are confined amongst the freshwater di- 
 vision of the AlgcB to the Characece. 
 
 In order that the nature of the circulation (which will first 
 be considered), carried on in the cells of the Characew, may be 
 more clearly understood, it will be advisable, previously to 
 entering upon its consideration, to give a general notion of 
 tlie structure of these curious productions. 
 
 Tlie order Characeoi is divided into two genera, Chara 
 and Nitella. The main stems of the difterent species of 
 
78 CIIARACEJE. 
 
 Chara, wlilch are all branched, consist of elongated cells 
 placed end to end, and tapering in size from below up- 
 wards ; surrounding these primary cells there are, in the per- 
 fect state of the plant, a number, in Chara vulgaris usually 
 eighteen, of smaller secondary cells : these take a spiral course 
 round the larger cell invariably from left to right. From 
 the upper extremity of each cell grow out nine arms or 
 smaller cells arranged in a campanulate manner; each of 
 these arms have four or five joints, from which issue the 
 organs of reproduction, to be described hereafter. From the 
 superior extremity of many of the cells also grow out branches, 
 and at the same time long and colourless branched articulated 
 roots are sent forth. The genus Nitella differs only from 
 Chara in the absence of the secondary spiral cells, and in 
 the number of arms which go to form each verticillum or 
 whorl. 
 
 The circulation in Chara was first noticed by Amici ; in 
 the two genera it does not diff«er materially, in both the course 
 is spiral; the fluid, with its granules, passing obliquely and 
 slowly from left to right uj) one side of the cell, turning 
 round its extremity and descending in the same manner on the 
 other side. A circulation of the same character prevails not 
 only in the main cells of the stems and branches, but also in the 
 secondary spiral cells or tubes, some of which are occasionally 
 articulated or divided into other small cells, each. In like 
 manner, having an Independent circulation. 
 
 Mr. Slack (Transactions Soc. of Arts, &c., vol. xlix. p. 1.) 
 long since observed, and the observation has been verified, 
 that the ascending current of the circulating fluid is always 
 in that half of each cell which is farthest from the axis of 
 the plant ; the descending, as a consequence, being confined 
 to the opposite half, or that which is nearest the axis. The 
 same observation Mr. Varley states to hold good in respect 
 to the roots, due allowance being made for the difference in 
 their direction, they, unlike the plant itself, taking a down- 
 ward course. 
 
 A deviation from the above-described circulation has been 
 noticed to occur in certain parts of Chara vulgaris by Mr. 
 
CHARACE^. 79 
 
 Solly, and has been described by Mr. Varley in one of his 
 excellent memoirs on Char a in the " Transactions of the Soc. of 
 Arts," vol. xlix. p. ii. This deviation occurs in many of the 
 cells which usually surround the seeds, and which are four 
 in number when complete. It occurs, see plate Lxr. fig. 1. 
 of the present work, in those cells or sprouts surrounding the 
 seeds marked a, h, c, d, e, f, g, h, in which the sap has taken 
 a circular or cylindrical course round the axis. Mr. Varley 
 thus minutely describes this deviation. 
 
 " Fig. 2. (pi. LXI.) is an enlarged view of the sprout a. The 
 circulation is over to the right, as shown by arrows ; it thus 
 far agrees with the spiral course, which is always to the right. 
 Near the point by the top arrow, there is such an accumu- 
 lation as to form a ring or thick mass very like a diaphragm ; 
 this mass keeps revolving on its own axis. Near the second 
 and thkd arrows the j^articles are more detached, each going 
 round in its own circle ; here the green studs, instead of being 
 arranged in a straight line, are slightly curved. Still lower 
 down, near the middle of the sprout, there is an inclined 
 elliptical circulation, shown by dots and arrows ; and from the 
 bottom, particles are seen rising nearly as high as the oval, 
 and descending again without appearing to follow any regular 
 course : these are shown by dots and arrows. 
 
 " Some of the particles in sprout (ci) were of sufiicicnt 
 size to be distinctly seen during the whole of their revolution, 
 which took place in about fourteen or fifteen seconds : this 
 observation was repeated by different persons, Avho nearly all 
 agreed as to the time of the revolution ; but in one of the 
 sprouts I observed three particles differing in their speed, 
 and occasionally passing each other. I counted their periods 
 by my own pulse ; one went round in nine beats, the next in 
 eleven ; these followed so nearly in the same track as to 
 move aside wliilst passing; the third sometimes occupied 
 twenty beats, and at other times twenty-five in going round. 
 They all appeared to keep to the circumference, and therefore 
 the difference in their periods is more worthy of being re- 
 marked, as seeming to indicate that each particle had some 
 cause of motion independent of the fluid in which it moved." 
 
80 CIlAPvACE^. 
 
 Various attempts have been made to determine the cause 
 of the remarkable circulation in Chara and Nitella. The in- 
 sufficiency for this purpose of the well-known laws of endos- 
 mosis and exosmosis has been ingeniously shown by Mr. Slack 
 in a note inserted in the Second Part of vol. xlix. of the 
 " Transactions of the Society of Arts," that lamented inquirer 
 having ascertained that the circulation continued in all plants 
 in which it has been observed when the portion was immersed 
 in oil or mucilage, and in strong saline solutions, and even 
 when not in contact with fluid of any sort, but surrounded 
 only by the dry atmosphere. 
 
 Tn a letter addressed to the Royal Academy of Sciecces, 
 of Paris, in the sitting of November 23d, 1829, by M. Du- 
 trochet, some highly interesting remarks occur relative to the 
 circulation of Chara. The discovery was made very many 
 years ago by Count Rumford, that water placed in vertical 
 tubes circulates. In order that the circulation of so transparent 
 a fluid may be the better appreciated it is requisite to suspend 
 in it some molecular substance, the best for which purpose M. 
 Dutrochet has found to be a few drops of milk, the specific 
 gravity of which is nearly equal to that of the water. Many 
 other substances will cumulate in water, such as very fine 
 sawdust, amber reduced to powder, and rasped cork ; but 
 these being of greater specific gravity than the element in 
 which they are suspended, sooner or later subside to the 
 bottom of the tube. 
 
 M. de Bailif illustrated, by means of an apparatus con- 
 structed on this principle, the circulation which takes place 
 in the cells of Chara, &c. M. Dutrochet, however, in the 
 letter above cited, examines this curious physical phenomenon 
 more closely. He found that the efficient cause of the cii'- 
 culation was caloric, that the rapidity of the motion depended 
 on the amount of caloric to which the tube and its contents 
 were subject, and that the direction of the current was go- 
 verned by the same agent, the ascending stream being placed 
 always on the side of the tube which received the most heat. 
 M. Dutrochet observed, moreover, that light exerted a power- 
 ful influence on the circulation, which influence Avas attri- 
 
CIIARACEiE. 81 
 
 butable to the caloric which accompanied its rays, and also that 
 mineral substances in solution accelerated its speed. The 
 caloric and the mioeral substances in solution were supposed 
 to exert this power by causing the greater separation of the 
 molecules of the water, and thus increasing their mobility. 
 Pressure was found to have a contrary influence, and to re- 
 tard the circulation by, it was presumed, occasioning the 
 closer approximation of the molecules, and so impeding their 
 mobility. Viscid organic matter, such as gum, produced the 
 same effect, and for a similar reason. 
 
 The causes not favourable to the sustenance of this physical 
 circulation, therefore, are, the absence of caloric, or cold, and 
 of light, upon which it follows that the motion ought not to 
 take place during the night, j^ressure, and the solution of 
 viscid substances in the liquid ; all of which act in the same 
 way, viz. by impeding the facility of motion between the 
 aqueous molecules. On the contrary, the favourable causes 
 are all those things which act In an opposite way, by increas- 
 ing that facility. 
 
 A very curious fact is related by Dutrochet in reference 
 to the circulation of aqueous fluid in tubes. It is this : that 
 if a drop or two of acid, of alkaline solution, or a solution 
 somewhat saline be added to the water contained in a tube, 
 and which has had milk mixed with it, these substances, more 
 weighty than water, precipitate themselves, and become dis- 
 solved. " This solution being achieved, the water Is no 
 longer susceptible of presenting the circulatory movement 
 by means of simple diffused light ; it only presents this move- 
 ment at its superior part, and this only when the tube is 
 exposed to the direct light of the sun, the continued action 
 of Avhich on the tube for many hours can scarcely penetrate 
 the circulation to the depth of an Inch in that water, whose 
 molecules have acquired a very extraordinary molecular Jixify. 
 I consider this fixity as the result of a regular disposition of 
 the molecules of the liquid. Indeed^ when one agitates this 
 liquid endowed with molecular fixity, it becomes immediately 
 susceptible of circulation under the influence of the simple 
 G 
 
82 CHARACE.E. 
 
 diffused light. The agitation has changed, as it would ap- 
 pear, the regular order of the molecules of the liquid, and 
 their aggregation has become confused. In this last state 
 they enjoy a mobility of which they were deprived in their 
 state of regular position ; and it is to be remarked that water 
 so changed with a mineral substance in solution and agitated, 
 has more molecular mobility, and is more susceptible of cir- 
 culation than was the pure water before this solution." 
 
 With the following extract, this epitome of Dutrochet's 
 letter on the circulation of Chara may be concluded : — 
 
 " After having filled tubes with acidulated milky Avater 
 I have closed them with the lamp. This liquid being fit 
 for circulation, being unalterable, and not Ijcing able to lose 
 any thing by evaporation, it follows that being exposed to 
 the light it possesses the condition of a perpetual circulatory 
 movement, with nocturnal intermissions, and further, with a 
 winter intermission, which exists but when the temj)erature 
 is inferior to 5° E. One might say, metaphorically, that this 
 liquid is, during the night, in a state of sleep, and during 
 the day, in a state of wakefulness ; one might say also that 
 its repose in winter is a state of hibernation. It might be 
 supposed at first view that these phenomena bore some ana- 
 logy to the state of sleep and of wakefulness of plants, and 
 to their state of hibernation." 
 
 A\\ experiment in reference to the circulation of the Cha- 
 racea may here be referred to, viz. that the application of a 
 ligature to the centre of a cell does not destroy the circulation 
 therein. 
 
 This experiment was originally made by Raspail. 
 
 A general description having now been given of the 
 structure and circulation of Chara and Nitella, a few other 
 particulars still remain to be noticed. 
 
 A delicate membrane lines the interior of each cell, 
 having little or no attachment to the one which constitutes 
 the proper cell membrane, and which is therefore easily 
 separable therefrom, save at the lateral colourless longitu- 
 dinal lines, which are formed probably by its attachment. 
 
ClIAUACEiE. 83 
 
 This mcmbmne is studded over with a number of minute 
 granules, which impart colour and texture to the plant. 
 This inner membrane is represented in fig. 7. Concerning 
 these granules, Mr. Varley makes some curious remarks : — 
 " The minute green bodies always adhere to the membrane, 
 and never to the outer tube. In some specimens these 
 green bodies are so regular as to leave only a very narrow 
 and even partition, whilst in others, the green studs are very 
 scanty and irregular at the parting lines, appearing rather 
 scattered about, as shewn in fig. 11. In such places, if 
 the green bodies be patiently watched through a doublet 
 l-60th focus, they will be seen occasionally to expand and 
 contract, change their form, move a little round, then more, 
 and then go on to a whole turn or more ; move forwards a 
 little, and sometimes start off out of the field ; some I have 
 followed till they stopped behind stationary ones, and I havie 
 seen some come into the field and be stopped ; also minute 
 darkish dots are seen running along between these studs, 
 and some of these would turn aside as by an eddy, and 
 stop between them. Again, whilst writing this, I have seen 
 some (where an open space had been made by bending 
 or teasing the stem) move forwards, and then return ; three 
 or four separate ones came together laterally, then went 
 forwards close to the regular and undisturbed ones ; they 
 then, after stojiping some time, came back, and parted a con- 
 siderable distance from each other, and with the motion of 
 others, they were lost to any further observation, and the 
 next day all the irregular oues had moved, and some parts 
 assumed a more regular arrangement." The singular move- 
 ments above described correspond precisely with those of 
 the Zoospores described in the Introduction, to which, in other 
 respects, one would not suppose them to be analogous. 
 
 Mr. Varley considers these green granules to be placed on 
 the external surface of the inner membrane, to which, from 
 their power of locomotion, they must be supposed to adhere 
 but feebly. The purpose which they serve in such a situation, 
 it is not easy to determine : were they adherent to the inner 
 G 2 
 
84 CHARACEiE. 
 
 surface of the membrane, their destination might be con- 
 jectured. The delicate and tender membrane itself might 
 be regarded as the matrix for the developemeut of these 
 granules, which, when mature quit it, and join the other 
 granular bodies contained in the circulating fluid, and the 
 nature of which is itself probably determined by their pre- 
 sence. That the granules studding the inner membrane do 
 in some way or other enter the circulating fluid, is rendered 
 highl}^ probable by the fact that the majority of particles 
 which it contains bear a close resemblance to these granules. 
 INIr. Varley further remarks in reference to these granules, 
 that if any of them, situated in the middle part of a cur- 
 rent, be disturbed by injury, no effect is j^roduced, the 
 stream passing on as before; but that if they be displaced 
 over the boundary lines, a communication takes place be- 
 tween the two currents ; a portion of the fluid near the 
 boundary line, instead of passing on to the end of the cells, 
 crosses over it into the returning current, and passes on 
 with it, a portion of the descending, in like manner, joining 
 the ascending and following its course. " I believe," says 
 Mr. Yarley, " that in this case the fine membrane is not 
 wounded, but is probably loosened from its adhesion to the 
 ridge, the green vesicles only being removed or injured : 
 but it shows that there is a most intimate connexion be- 
 tween these vesicles and the circulation ; and they appear to 
 govern the circulation ; for in the case above stated, where a 
 clear space was refilled Avith green vesicles anastomosing 
 had taken place ; but when the spot Avas again coated with 
 vesicles, the anastomosing also ceased, the fluid having 
 again taken its direct course, coinciding correctly with the 
 track marked out by their arrangement. I am led to think 
 that any Avound of the membrane Avould kill that whole cell, 
 by submerging the A'cslcles in the thick or the inner fluid, and 
 thus cutting oif the continuity of their action, or by the 
 different fluids mixing and so destroying their action. The 
 fine membrane Avith the vesicles is seldom remoA'ed far 
 enough from the tube to shcAv the colourless space bctAveen 
 
CnARACEiE. 85 
 
 (though I liavc samples before me now that shew it) ; there- 
 fore the fluid which passes between the vesicles must be 
 very small in quantity, and is so limpid as to be difficult to 
 discover." 
 
 In what way the removal or injury of the granules, j^laccd, 
 according to Mr. Varley, on the outer surface of the mem- 
 brane can influence or govern the circulation carried on 
 within that membrane, it is difficult to conceive. It seema 
 to rae, that the anastomosing of the currents can only be 
 accounted for by adopting the view of Mr. Slack, relative to 
 the internal organization of the Characcce to be mentioned 
 presently, or by supposing the internal membrane to be 
 ruptured in the situation of the boundary line, thus permit- 
 ting an escape of the circulating fluids from the interior of 
 the membrane to its exterior, and so deranging the dis- 
 position of the granules. 
 
 Within the membrane which has been just described is the 
 proper circulating fluid of the plant, which, in full motion, is 
 dense and thick, though transparent, containing a variable 
 number of solid granules, which circulate Avith it in the 
 course abeady indicated from left to right. The granules 
 do not, however, all move with equal velocity, or in a pro- 
 cession as it were. 
 
 Internal to this fluid, and occupying the centre or axis 
 of the cell is another fluid, almost quiescent, and usually free 
 from solid admixture. This is generally greater in quantity 
 than the former or circulating fluid. 
 
 " These two fluids being of diffi^rent densities," accord- 
 ing to Mr. Varley, " do not when the plant is in health 
 mingle, and are not separated by a membrane. Accordino- 
 to INIr. Slack," however, a membrane does exist between the 
 different fluids, enveloping the central, and forming an 
 axis for the circulating fluid to revolve on, usually becomino- 
 attached in the course of the longitudinal boundary lines, 
 thus separating the two currents of the circulating fluid 
 from each other. It can now be understood in Avhat way 
 injury to this membrane, if it really exist, would occasion the 
 
 G 3 
 
86 CHARACEiE. 
 
 intermingling and anastomosing of the cm-rents described hy 
 Mr. Varley." 
 
 This membrane, which must be of exceeding tenuity, is, 
 however, in unhealthy states of the plant no doubt wanting. 
 In certain states of Chara, several large spherical masses 
 are noticed in the central fluid : these are supposed to consist 
 of portions of the innermost dense circulating fluid which 
 have become detached ; and it is by means of these that the 
 absence of the membrane can be demonstrated. The thick 
 circulating fluid does not seem to be visibly affected by 
 gravity, for it follows its usual course in whatever position 
 the cell may be placed : the spherical bodies, which are de- 
 scribed by Ijoth Mr. Varley and Mr. Slack, are, however, 
 sensibly aifected by gravity : if the cell be placed horizontally 
 and one of these bodies be in the superior current, it will de- 
 scend, slackening its speed as it enters the middle fluid, revolv- 
 ing as it jjasses through it, and returning by the lower cur- 
 rents : then again, if the plant be reversed, the same globules 
 will again descend, and enter the former stream. The passage 
 of globules from current to current through the central fluid 
 proves that there is now no membrane surrounding it, and 
 also that the central fluid is lighter than the circulating. 
 Fig. 11. represents a cell containing several of these balls or 
 globules. 
 
 For the purpose of tracing and following the course of 
 these globules an apparatus, similar to INIr. Varley's vial 
 microscojDC, is necessary. Having now completed the con- 
 sideration of the circulation in the Characece, it remains 
 to treat of the rej)roduction of the order — a subject always 
 of the highest interest in productions belonging to the fresh- 
 water division of the Alff<s. 
 
 We will first describe the organs as they occur in Chara 
 vulgaris^ and which will serve as the type of the whole order. 
 
 The branches which compose each whorl in Chara vulgaris 
 are usually nine in number, and consist of four or five cells, 
 the lower ones of wliich are surrounded by nine other smaller 
 cells, which pm'sue, like those covering the cells of the stems, a 
 sjiiral course. At the junction of the major cells with each otherj 
 
CHAKACEii:. 87 
 
 and which are surrounded by the nine smaller spiral cells, arise 
 or are placed the organs of reproduction : these arc of two kinds, 
 nucules and globules, which have been denominated male and 
 female ; the upper being regarded as the female and the lower 
 as the male apparatus. The female apparatus or nucule con- 
 feists of a seed-vessel, which is composed of a membranous and 
 brittle envelope, around which are wrapped five spiral cells, 
 surmounted or crowned by five smaller cells. The cells, it is 
 remarkable, pass from right to left, that is, in a direction the 
 reverse of the cells on the stems and branches, and contrary 
 also to the course of the circulation. (See pi. lxi. fig. 4.) In all 
 these cells circulation is carried on. The brittle envelope re- 
 ferred to may not be a real organized membrane. Each seed- 
 vessel, according to the observations of INIr.Varley and others, 
 contains but a single nucleus or germ, which has a proper 
 envelope : when young, it is of a green colour, the tubes 
 being colourless : as it ripens it becomes darker, and then 
 begins to fade away, and ultimately separates and disappears. 
 The seed or nucleus is then ripe, and ready to separate, con- 
 nected only by the brittle envelope, which is entirely soluble 
 iu acids. When this is removed the nucleus or kernel ajapcars 
 Avith its dark and shining skin, " which is flexible and tough 
 enough to bear squeezing out of shape." On the rupture of 
 this the contents issue forth, which are compared to wheat 
 flour by Mr. Varley. Such is a brief outline ofthe seed and 
 seed-vessels : the structure of the male blossom, if it may 
 be so termed, is more complicated. It is spherical and 
 situated beneath the seed-vessel, surrounded by its four 
 sprouts or cells. (See pi. lxi. fig. 4.) Although these globules, 
 as well as the seed-vessel or nucleus, are placed at the junc- 
 ture of the principal cells with each other, they do not arise 
 directly from these, but rest on a number of smaller cells, 
 which are there found, and which, as some of them present 
 phenomena, which are peculiar, and which are accurately de- 
 scribed by Varley in vol. iv. part 1., it will be well to notice 
 before following up the anatomy of the globule. The cells 
 which present these peculiar phenomena are, first, that upon 
 which rests the stalk of the globule ; secondly, that which sup- 
 G 4 
 
88 CHARACE.E. 
 
 ports the stalk of the seed-vessel ; and thirdly and fonrthlyj 
 two other cells, which lie on each side of the cell, supporting 
 the stalk of the globule. " In ordinary tubes or cells," Mr. Var- 
 ley writes, " there are green vesicles regularly arranged on 
 the thin membrane which lines them, and the circulating fluid 
 appears thickened by innumerable particles, a little denser, or 
 not quite fluid, and with scarcely any colour. But in these 
 peculiar cells there are generally very few stationary green 
 vesicles, except about the angles formed by the adhesion of 
 other cells. The fluid within is very clear and limpid, with 
 many very equally sized green granules floating in it. Those 
 that are still, and those that are moving, appear to be the 
 same ; and some are seen to stop, and some stationary ones 
 are seen to break loose and go on : they are rather larger 
 than the orderly arranged green vesicles of other cells ; but 
 being loose, and the cells so glossy, they are seen very bright 
 and distinct. This is not all ; for they circulate round the 
 cells very quickly and freely, undergoing some extraordinary 
 influence; for they knock against one another, appear to 
 stick at some places, or as if they squeezed by, and then rush 
 on quicker ; many, as they come near particular parts of the 
 cells, spin round most rapidly as they go on, different particles 
 turning in opposite directions ; and others only catch a slight 
 impulse to spin, suddenly tm-ning round and back again, and 
 go on without spinning ; others, near the centre of rotation, 
 go round together, then start into a quick whirl, then vary 
 or slacken, and again start into a furious whirl, showing 
 considerable fluctuations in their motion ; and in the larger 
 rounds they appear to receive some impulse whenever they 
 touch that part of the surface which joins the arm, as though 
 they were slightly electrified." These motions precisely re- 
 semble those of the zoospores, and are doubtless voluntary, 
 performed, as in their case, by means of vibratile organs or 
 cilia. 
 
 We will now describe the globule itself: this, as has 
 already been observed, is spherical, with a light red nucleus, 
 the coating being made up of about eight deeply indented 
 triangular segments. (See plate LXi. fig. 4.) These con- 
 
CHAKACEvE. 89 
 
 tain a number of small red granules, to which the colour 
 of the globule is principally owing. AVithin these segments 
 are noticed, first, the stalk of the globule, which is pyri- 
 form, and rests upon one of the peculiar cells which have 
 been described. Upon the summit of this stalk rests a num- 
 ber of smaller spherical or pyrlfonn cells : these occupy the 
 centre of the globule, and from them proceed a number of 
 large cells to be inserted into the segments which fomi the 
 coating of the membrane, and by means of which their seg- 
 ments are retained in their proper situation. These last cells 
 correspond in number w^ith the segments, one going to each. 
 Lastly, interwoven together, and filling the interstices be- 
 tween the cells, are numerous fine articulated threads, to be 
 more particularly referred to hereafter. 
 
 Now in the footstalks of the nucules and those of the globules, 
 as well as in the radiating cells attached to the segments, a 
 peculiar body or vesicle is noticed. This was first, I believe, 
 discovered by Mr. Varley, but has since been noticed and de- 
 scribed by other observers; although its office has not yet 
 
 been determined. This vesicle is situated in the circulatino- 
 
 o 
 
 fluid of the cells, the course of which it follows, although 
 from its size it frequently projects some distance into the 
 central fluid. 
 
 In the stalk of the globule, and in those of the segments, 
 in addition to the transparent vesicle, there are membranes 
 studded with vesicles similar to those of the external and 
 ordinary cells, and in like manner arranged so as to show the 
 ascending and descending currents ; but instead of being green, 
 as in the former case, they are bright red. 
 
 AVe now come to relate the most extraordinary circum- 
 stance, not without parallel, however, in the vegetable king- 
 dom, connected with the history of these most interesting 
 productions. The spaces between the stalks of the seg- 
 ments, it has been remarked, are filled up with entangled 
 filaments or vessels which appear ringed. The contents of 
 each division betwegi the rings first appear angular, and sub- 
 sequently resemble a thread coiled up ; " after a while," to 
 adopt the language of the first discoverer of the fact, " these 
 
90 CHARACEiE. 
 
 coils (see pi. LXii. fig. 3.) within the divisions become agitated ; 
 some shake or vibrate about, others revolve in their confined 
 places, and many come out, thus showing that they are 
 spirals of two or three coils, and then with an agitated motion 
 swim about. Now the field of view appears filled with life ; 
 great numbers of these spirals are seen agitated and moving in 
 all directions ; they all have a directive force, one end always 
 going foremost and never the other ; many stray a great way 
 out of the field ; these, by getting clear of each other, are 
 best to observe ; they do not quite keep their form as a stiiF 
 spiral, but their foremost end seems to lash about ; and to 
 many are seen attached (see plate LXii. figs. 5, 6.) almost invi- 
 sible but very loug fibres. These fibres were in quick undu- 
 lations, which rose in waves from the spiral to their farthest 
 end. It appears that these fibres cause many of the spirals 
 to entangle together, and thus bring them to a state of rest ; 
 therefore the separate ones were best to observe." 
 
 With a few other remarks this brief description of the 
 CharacecB may be terminated. The spiral disposition of 
 organs seems to prevail almost universally throughout the 
 works of nature. The most superficial observer could not 
 be at a loss for a single moment to point out examples of it. 
 In the zoophytes this arrangement of parts is especially ob- 
 vious ; in no order of productions is it, however, more ap- 
 parent than in that which is under discussion. The tubes 
 which enfold the main cells are spirally disposed; the cir- 
 culation in these cells follows a spiral course ; and lastly, the 
 cells of the seed-vessel are exactly, simply, and beautifully 
 spiral ; exactitude, simiDlicity, and beauty being the chief cha- 
 racteristics of the spiral disposition or formation. 
 
 The preceding pages embody an accurate and minute de- 
 scription of the different parts constituting the structure of the 
 order CharacecB, and of the different remarkable phenomena 
 presented in those parts ; so accurate, indeed, as to leave but 
 little to be desired in this respect : and yet, how much remains 
 to be solved and explained ! how deep is the mystery which 
 veils the right understanding of the different actions Avhich 
 have been detailed ! The following questions may be pro- 
 
CHARACEiK. 91 
 
 posed, but who shall answer them ? Is the globule really the 
 luale apparatus ? and are the spiral coils which may be 
 denominated animalcula the agents whereby the seeds are 
 fertilized? and if so, in what way do they eifect this grand 
 and prime object ? what also is the nature of those numerous 
 particles contained in the peculiar cells Avhose motion seems 
 only to be regulated by individual will, and what is the office 
 over which the vesicles in the cells of the footstalks preside ? 
 
 M. Bischoff (Die Cryptogamischen Gewiichse, Ire livr., 
 1828) was the first to observe the animalcula of Cliara. 
 Using a microscope of but feeble power, however, he did 
 not make out their origin. Afterwards ISIeyen gave very 
 imperfect figures of them in the " Annales des Sciences Na- 
 turelles," t. x. p. 319. pi. 10. 1838. Mr. Varley, however, 
 from whose excellent papers I have had occasion to draw so 
 lai'gely, appears to be the first observer, who gave an ac- 
 curate, minute, and complete description of them in his paper 
 in the " Trans, of Society of Arts," published in 1834 ; a 
 paper, with the existence of which M. Gustave Thuret did 
 not seem acquainted when he published his excellent memoir 
 " Sur I'Anthere du Chara" in the 14th volume, second serlesj 
 of the " Annales des Sciences Naturelles," 1 840, as no allusion 
 is made to it therein, and the facts detailed do not differ in 
 any essential particular from those previously made knowai 
 by ISIr. C. Varley. 
 
 INI. Peyen has examined the CharacecE. chemically. The 
 following are the more important of his remarks : — 
 
 " Tlie orange-coloured vesicles (globules) which are seen on 
 the branches of Chara contain, as is known, cellules very 
 long and flexible. I have ascertained that their fine mem- 
 branes have the chemical composition of vegetable tissue, 
 while the substances enclosed by them present the azotized 
 composition proper to bodies enveloped in the young organs 
 of plants." 
 
 " These analytical results appear to me to be natural con- 
 sequences of the constitution of the reproductive organs of 
 Chara, such as M. Brongniart has indicated not only as to 
 the monospermic grain, but also relatively to the azotized 
 
92 CHARACE^. 
 
 substances contained in the vegetable membranes which are 
 related to the pollen of the male organ." 
 
 " These chemical facts should be in harmony with the ob- 
 servations of M. Meyen and those of M. Brougniart ujaon the 
 spontaneous movements of little bodies enclosed in the pollen. 
 (Ann. des Sc. Nat., Nov. et Dec. 1838.) The particles of 
 Brown are found in my experiments to have an azotized 
 quaternary composition." 
 
 The monospermic grain is composed chiefly, as was first 
 indicated by Easpail, of farina. 
 
 The affinities of the order Characece are by no means 
 striking or satisfactorily determined. In being composed of 
 tubular cells, and in the disposition of these they exhibit a 
 relation to the Confervoid AlgcB generally, in the arrangement 
 of their branches in whorls, and in the circumstance of the 
 primary being crusted with other secondary and descending 
 cells, they manifest a relationship with the Batrachosperms 
 in particular. In their organs of reproduction, and in cer- 
 tain other I'espects, they bear some resemblance to the Equi- 
 seta, I know not how exact however. The Characece are not 
 the only order of freshwater AlgcB possessing double organs 
 of reproduction : as, for example, Vaiicheria. Linnteus first 
 referred the CharacecB to the Cryptogamia, but subsequently, 
 regarding the globules as stamens and the nucules as pistils, 
 he removed them to Monoecia Monandria amongst flowering 
 plants. 
 
 The Characece are almost universally distributed : they are 
 found abundantly both in fresh and stagnant waters, in all parts 
 of tlie world. They form an important link in the economy 
 of Nature, in life purifying by the liberation of oxygen during 
 respiration, the impure and almost pestilential waters in Avhich 
 they are frequently and especially encountered, and in death 
 yielding by their decomposition elements which impart fer- 
 tility to the soil, and render it fit for the growth and nourisli- 
 ment of plants of an order higher in the scale of organization 
 than themselves, and of more dii'ect utility to man, the destined 
 reci^Dient of all Nature's bounties, and for whose benefit every 
 natural contrivance directly tends. Let this thought impress 
 
CHARACEiE. 93 
 
 the heart with the conviction of the goodness of God towards 
 man, who often ungratefully omits to remember it, and 
 who therefore needs to be from time to time reminded of it. 
 The important part which the Characca take in the formation 
 of the earth's strata, geological investigation has made strik- 
 ingly and beautifully manifest, their fossil remains having 
 been found in great abundance in the freshAvater strata 
 covering the chalk formation in the Isle of Wight, and in the 
 marls of Forfarshire, and other places — their remains con- 
 sisting of portions of the stems, but principally of the nucules 
 which Lamark mistook for the shells of testaceous animals, 
 and acting under this impression named them Gyrogonites. 
 The fossil remains found in the calcareous marls of Forfar- 
 shire have been identified as belonging to Chara liispida, the 
 same species still existing in a living state in great profusion 
 in tlie lakes whicli still cover portions of these marls. 
 
 The one grand purpose for which all cryptogamic vegetation 
 would appear to have been created, is the formation of soil 
 for the growth of productions more necessary to the wants of 
 man. First, the lichen, stunted and dry, but rich in salts, 
 appears on the face of the primordial rock. The rains of 
 Heaven descend upon It and moisten it, causing the dissolu- 
 tion of a portion of the rock itself: this it quickly Imbibes 
 and retains in a more soluble form. It lives Its allotted time, 
 then dies, and decomjooses, liberating what it had derived from 
 the rock, together with the constituents of its own fabric. By 
 the continued and successive growth of the lichens, however, 
 a portion of the surface of the rock becomes hollowed out, 
 and a pool of water rests therein. The lichens noAv finding 
 this no longer a place fit for their developement, dlsapjDcar. 
 Ere long, however, the sporules of a moss or a conferva lio-ht 
 upon this spot, and finding therein the circumstances requisite 
 for their growth, grow and flourish there for a period. Each 
 season they die also, and the quantity of their debris annually 
 increases, so that at last the pool is filled up : next in order 
 Equisefa, Cariccs, and Junci appear, and finally a soil is col- 
 lected, rich In the elements of fertility. The fungi assist much 
 in the formation of soil; but in a very different manner. 
 
94 CHABACEiE. 
 
 Tliey require for their growth liighlj^ nutritious substances, 
 such as dead organic matter : this by their thalH, or thousand 
 rootlets, they quickly disorganize, appropriating a small por- 
 tion of it to their own nourishment, but allowing the return 
 to earth, to be again appropriated in some other form of tissue, 
 of by far the greater portion of those substances. 
 
 The CharcB are frequently called Stoneworts, from the 
 quantity of calcareous matter Avitli -which they are often in- 
 crusted, or perhaps which they evolve, this property rendering 
 them agents still more important in the formation of soil. 
 
 5. NITELLA Ag. 
 
 Char. Plant more or less pellucid. Cells tubular, not in- 
 vested icith a secondary layer of smaller cells. Globules 
 and nucules mostly on the terminal ivhorls, and axillary. 
 
 Of this and the following genus no figures are proposed 
 to be given, as their inclusion did not enter into the original 
 intention of the work. This is the less to be regretted, as very 
 good figures of the species are extant, especially those of 
 " Eng. Bot." 
 
 1. NiTELLA TRANSLUCENS Ay. 
 
 Char. Stem elonyated, Jlaccid, jyellucid, glossy ; branches of 
 the lohorls spreading, elongated. Nucules and globules 
 approximate, on the smaller ramuli scarcely bracteated. 
 Chara translucens, Eng, Bot. 1855, 2d ed. t. 1467, Hook. 
 Crypt. El. part 1. p. 245. ; Macreight, 278. ; Nitella 
 translucens Ag. Syst. Alg, 124. 
 
 This species grows in deep and stagnant jDonds : it has been 
 found in several localities, but is by no means common. It 
 is the largest of our native species, and well adapted, from its 
 transparency, for microscopic examination, of which it has 
 often been made the subject. The whole plant is exceedingly 
 smooth and glossy, whence its name. The distance of the 
 whorls, and thickness and size of the branches, vary in differ- 
 ent specimens. Fructification met witli from July to Sep- 
 tember. 
 
NITELLA. 95 
 
 2. NlTELLA FLEXTLIS A(/. 
 
 Char. Stems repeatedly dichotomous, one to two feet lony, 
 smooth, jiaccid, somewhat glossy, and pellucid : harder s of 
 the 7chorls compound, ohtuse. Nucules and globules ap- 
 proximate, fexo, scarcely hracteated. 
 
 Chara Jlexilis, Eng. Bot. t. 1070. ; Eng. Bot. (2d cd.) 
 t. 1468., and fig. c to /, t. 1472. ; Smith, 1.7.; Hook. 
 Crypt. Fl. part 1. p. 245. ; Macreight, 278. Nitclla 
 Jlexilis Ag. Syst. 124. 
 
 " Not unfrequent in ditches, lakes, and still waters. A 
 much weaker and more slender plant than the last, with the 
 Ijranchcs of the whorls generally, but not always forked, or 
 divided into three or four segments, rarely all simple. Nucules 
 often solitary. It is never so glossy and bright in its hue 
 as N. translucens, and not uncommonly is found more or less 
 incrusted with calcareous matter, rendering the stems some- 
 what opaque : in this latter state it is N. opaca of Agardh." 
 — Eng. Bot., 2d ed. 
 
 3. NiTELLA NIDIFICA Ag. 
 
 Char. Stems simple, below smooth, Jlaccid, someiohat glossy, 
 and pellucid : primary whorled branches simple, elongated ; 
 fertile ones numerous, crowded, proliferous. Nucules 
 and globules separate, hracteated. 
 Chara nidijica, Eng. Bot. t. 1703., 2d ed. t. 1469. ; Smith, 
 1. 8. ; Hook. Crypt. Fl. part 1. p. 245. ; Macreight, 278. 
 Nitclla nidijica Ag. Syst. 125. 
 
 " A native of saltwater ditches in the South and East of 
 England. The simple much elongated branches of the pri- 
 mary whorls, and the crowded and proliferous character of 
 the fertile ones, form the chief distinctions of the species, the 
 globules and nucules not being always separate. I have 
 found the globule stalked, but that occasionally occurs in N. 
 Jlexilis, and it is not uniformly so in the present plant. 
 
 " It would be desirable to ascertain the effect of cultivation 
 in perfectly fresh water upon this species, as sj)ecimens of a 
 
96 CHARACE^. 
 
 Nitella, collected in the vicinity of Ely, .seem to be inter- 
 mediatebetween it and N. translucens. The suggestion thrown 
 out by Sir W. J. Hooker that our native Nitella may be all 
 varieties of a single species, as our CharcB are perhaps of a 
 second, is far from improbable." — E. B. 2d edit. 
 
 4. Nitella gracilis A^. 
 
 Char. Stems smooth, glossy, pellucid ; branches of the ivhorls 
 compound, their segments acute ; the upper ones often all 
 fertile. Bracteas xoanting. 
 Chara gracilis, Eng. Bot. t. 2140. 2d edit. 1470.; Smith, i. 
 9. ; Hook. Crypt. Part 1. p. 245. ; Macreight, 278. Ni- 
 tella gracilis Kg. Syst. p. 125. 
 
 " Found in boggy pools in St. Leonard's Forest, Sussex : 
 in Llyn Idmel, North Wales ; and in Jersey. Pale green, 
 shining, very transparent. Fructification axillary in the di- 
 visions of the branches of tlie upper M'horls ; generally one 
 nucule and one globule, side by side, sometimes separate, and, 
 according to Mr. Wilson, on different plants. 
 
 " A small, very delicate, and elegant species, but only 
 doubtfully distinct from N. flexilis:' — E. B. 2d edit. 
 
 6. CHARA. 
 
 Char. Plant more or less opaque, very brittle ; striated, often 
 spirally. Primary cells, excepting the ultimate ones of the 
 branches which are uncovered, invested by a layer of 
 secondary smaller cells, ichich take a spiral course. Glo- 
 bules and nucules regularly dispersed along the lohorled 
 branches. 
 
 1. Chara vulgaris. 
 
 Char. Stem smooth, opaque, brittle, obscurely striated. Pri- 
 mary cells of the stems invested ivith about eighteen smaller 
 spiral cells ; those of the branches or ivhorls ivith about half 
 that number. Nucule bractcatcd. Bracts visually four, 
 much longer than the nucule. 
 
CHARA. 97 
 
 Chara vulgaris, E. B. 336. 2cl edit. 1471; Smith, i. 6. ; 
 Hook. Crypt., Part 1. p. 246.; Macrcight, 278.; Agardh, 
 Syst. Alg. p. 128. 
 
 Tliis is the commonest species of the whole genus : it is 
 met with in ponds, ditches, and slow streams, and is usually 
 of a yellowish green hue. The stems arc sometimes seven 
 or eight inches long. Whorls about as long as the articula- 
 tions of the stem, the upper ones alone being fertile. This 
 Chara, fi'om its great abundance, has most frequently been 
 the subject of microscopic observation, and amply has it re- 
 warded the labours of investigators. 
 
 2. Chara Hedwigii. 
 
 Char. Stem smooth, striated, opaque, somewhat brittle, elon- 
 gated. Branches of the lohorls subulate ; fertile ones with 
 many whorls of sho7-t raniidi or hractece, of tvhich the 
 longest are shorter than the fruit. Nucule ovate. 
 Chara Hedwigii, E. B. Suppl. t. 2762. 2d edit. 1472, in 
 part; Hook. Crypt., Part 1. p. 246.; Macreight, 278. 
 
 " Met Avith forming dense patches at the bottom of still 
 pools in several parts of the kingdom. Stems much longer 
 and more slender than in C. vulgaris ; and the whole jjlant of 
 a bright green colour, but sometimes jjartially incrusted ; 
 rather flexible when freshly gathered : each joint appears to 
 be divided about the middle in consequence of the smaller 
 tubes, forming the wall, being articulated midway as well 
 as at the principal joints. Nucule much larger than its 
 accompanying globule; about as long as, or rather longer than 
 the three or four apparent bracteaj which accompany it." 
 -E. B. 
 
 3. Chara pulchella. 
 
 Char. Stem smooth, striated, flexible. Branches o/ M^ whorls 
 subulate; the fertile ones with many whorls of short 
 ramuli or bractece, the longest of ivhich are about the length 
 of the nucule, l^ucule oblong. 
 H 
 
98 CHARACE^. 
 
 Chara pulchella, Eng. Bot. sup. 2824, 2d ed. 1473. Wal- 
 roth Ann. Bot. 184. tab. 2. C. pulcliella glohularis, Wallr. 
 Fl. Crypt. German, vol.2. 108. 
 
 Found by Mr. Borrer In Sussex. 
 
 " Distinguished from C. Hedicigii principally by its more 
 flexible stems and more oblong nucules. When dry, it is 
 scarcely at all brittle, whereas C. Hedioigii is extremely so, 
 whence it is called C. fragilis by some authors." 
 
 Perhaps merely a variety of C. Hedwigii. 
 
 4. Chara aspera. 
 
 Char. Stem very slender, scarcely brittle, obscurely striated 
 beset with scattered, spreading, or dejlexedbristles. Branches 
 of the whorls subulate ; the fertile ones ivith many lohorls 
 of short ramidi or bractea, the two innermost longer than 
 the rest, bearing the globules or nucules which are 
 generally separate. 
 Chara aspera, Eng. Bot. Suppl. 2d ed. 1474 ; Hook. Crypt. 
 Flor. Part 1. p. 246.; Macreight, 278.; Greville, Scot, 
 Crypt. Flor. 339.; Agardh, Syst. Alg. 130. 
 
 *' Found in bog pits, and still waters In several places In 
 the north of England and Scotland. Stem one or two feet 
 long, densely crowded, every where beset with acute, slender, 
 straight, spreading or deflexed bristles ; and having at the base 
 of each whorl a row of appressed bristles, connected In pairs, 
 of wlilch one points upwards and the other downwards. 
 
 "Between the outer cu-cle of tubes and central one, 
 in both the stems and branches. Is found a green parenchyma, 
 arranged in lines alternating with the strire, and separated or 
 broken transversely at intervals, giving them a spotted ap- 
 pearance; globules and nucules solitary, often on separate 
 plants. 
 
 " I have had this species under cultivation in a glass jar for 
 several years, and although no nucules appeared at any time 
 upon it, young plants were copiously produced every spring." 
 
CHARA. 99 
 
 5. CiiARA nisriDA. 
 
 Char. Stem more or less thickly covered loith a calca- 
 reous crust, oj)oque, brittle, striated, spinulose, or hispid. 
 Branches of the ivhorls subulate ; the fertile ones with many 
 lohorls of short ramuli or bractcce, of lohich three or four 
 are larger tlian the nucule and globule that they accom- 
 j)any. 
 
 Chara hispida, Eng. Bot. 463. 2d ed. 1475; Smith, \. 7. ; 
 Hook. Crypt. Part 1. p. 246. ; Macreight, 278. ; Ag. Syst. 
 128. 
 
 " Not uncommon in ditches, lakes, and turfy bog pools. 
 The stony incrustation is sometimes so thick as to give the 
 plant the aiDpearance of a petrifaction, which in other habitats 
 is nearly Avanting. Almost as foetid as C. vulgaris. It is 
 by far the largest of the true Charce in this country in its 
 ordinary form ; and, though varying in the thickness of its 
 stem and branches, can never be confounded with the slender 
 and more delicate C. asjjera. 
 
 " A smaller variety is occasionally met with in which the 
 spinules are obsolete, or nearly so : the C. hispida /3' of 
 Agardh and Smith, /3 gracilis of Hooker, Eng. Bot." 
 
 6. Chara latifolia. 
 
 '' This fine species, which I have no hesitation in statino" to 
 be new to Britain, occurred in great abundance in Belvidcre 
 Lake, county Westmeath, where I collected it in August last. 
 The great size and semipellucid appearance at once struck 
 me as remarkable. The main branches are striated and 
 covered with raised rough points, as are the first joints of the 
 whorled ramuli, Avhile the remaining portion consists only of 
 one pellucid tube, which is thicker than the lower joints, and 
 ends in a sharp point. The branches of the whorls are again 
 beset with smaller ramuli (not bractero), in which respect it 
 differs from all our species in the opaque division. 1 regret 
 I could not find the species in fruit, neither globule nor 
 
 H 2 
 
100 CHATIACE^. 
 
 nucule was present; though I examined hundreds of speci- 
 mens in various parts of the lake, where it sometimes 
 covered the bottom to the extent of many square perches ; 
 and what is singular enough, all the other species in the opaque 
 division occurred abundantly in the same lake, and were all 
 in fruit, each preser\ang its respective character." — D. Moore, 
 in ''Journal of Botany,'' p. 43. 
 
 The application of the specific name latifoUa seems to be 
 peculiarly inappropriate to a plant which, strictly speaking, 
 has no leaves at all. 
 
 " God is said to be Maximus in minimis. We Men esteem it a more diffi- 
 cult Matter, and of greater Ai't and Curiosity, to frame a small AVatcli than 
 a large Clock : And no Man blames him who spent his whole Time in the 
 Consideration of the Nature and Works of a Bee, or thinks his Subject 
 was too narrow. Let us not then esteem anything contemptible, or in- 
 considerable, or below our notice taking ; for this is to derogate from 
 the Wisdom and Art of the Creator, and to confess ourselves unworthy 
 of those Endowments of Knowledge and Understanding which he hath 
 bestowed on us. Do we praise Dccdalus, and Ai-chytas, and Hero, and 
 Callicratcs, and Albertus Magnus, and many others which I might mention, 
 ibr their Cunning in inventing, and Dexterity in framing and composing 
 a few dead Engines, or Movements, and shall we not admire and magnifie 
 the Great Arj/xiovpyoc Koo-juou, Foriner of the World, who hath made so 
 many, yea, I may say, innumerable, rare Pieces, and those too not dead 
 ones, such as cease presently to move so soon as the spring is down ; but 
 all living, and themselves performing their own Motions, and those so in- 
 tricate and various, and requiring such a Multitude of Parts and sub- 
 ordinate ISIachines, that it is incomprehensible what Art, and Skill, and 
 Industry, must be employed in the framing of one of them?" — Ray. 
 
101 
 
 Fa^i. vl BATRACHOSPERME^. 
 
 Char. Algas gelatinous^ monilifonn, ramose, articulated, 
 verticillate, filaments of the verticilli dense, dichotomous, 
 and headed, the inferior ones simple, descending, and 
 forming a sheath around the primary cells. Reproduction 
 consisting of glomendes scattered throughout the verticilli, 
 to which they are attached by a single filament or thread. 
 
 7. BATRACHOSPERMUM. 
 
 Char. Same as those of the family. 
 
 Derivation. From (Barpa'xps, a frog, and cirspixa, seed; 
 the siJecies resembling frog-spawn. 
 
 Dillenius discriminated many species or varieties of this 
 genus in his " Historia Muscorum/' under the name of Algce 
 luhrices. Linnajus, however, after him, united them all into 
 one species, under the name of Conferva gelatinosa, in which 
 example he was followed by succeeding botanists. 
 
 Weiss first removed the Conferva fontana, nodosa, spermatis 
 ranarum instar, lubrica et viridis, of Dillenius from the genus 
 Conferva, perceiving that it possessed a structure much 
 more complicated than that of the greater number of the 
 species of that genus, which are for the most part exceed- 
 ingly simple, and placed it amongst the Characece, under the 
 name of Chara hatrachosperma ; the term batrachosperma 
 implying the resemblance Avhich Weiss noticed between the 
 Conferva wliich he examined, and the series of gelatinous 
 globules in which are enclosed the eggs of the greater part 
 of the Amphibia of the family of frogs. 
 
 If it was requisite that tliis species should be removed 
 from the genus Conferva, it soon became apparent that it 
 could not be permitted to remain with the Characecs, and 
 the propriety of instituting a new genus for Its reception 
 quickly became apparent. 
 
 " In the year 3," says Bor^^ " I established this genus 
 in my collection. I communicated It to my learned friend 
 u 3 
 
102 BATRACHOSPERME^. 
 
 Draparnaud, and that skilful naturalist approved of it. 
 Roth, and after him Vaucher and Decandolle, have adopted it, 
 with the trivial name of Weiss, which has become general." 
 
 The Batracliosperms are highly flexible and mucous to the 
 touch, their lubricity arising in a measure from the presence 
 of innumerable lashes or cilia, terminating the branches, 
 which add also infinitely to the microscopic beauty of these 
 productions. Vaucher entertained the idea that they were to 
 be regarded as the stamina of the plant, and that they were 
 filled with a fecundating powder. This opinion Avould 
 appear to be mere conjecture, the only fact in support of 
 it being the deciduous character of the organs. Each 
 ciliura is articulated in a manner similar to that of the 
 branches, of which they may be regarded as extensions. 
 
 The species of this genus inhabit mostly pure and run- 
 ning waters, being usually met with in fountains, wells, and 
 streams, the force of which is not considerable. They are 
 so exceedingly flexible, that they obey the slightest motion 
 of the fluid which surrounds them, and would seem almost 
 to be endowed with vitality; nothing can surpass the ease 
 and grace of their movements. When removed from the 
 water they lose all form, and appear like pieces of jelly, 
 without trace of organization, on immersion however the 
 branches again quickly resume their former disposition. They 
 adhere strongly to paper, and in drying frequently change 
 to some other tint, usually much deeper ; on being moistened 
 after long intervals, they recover much of their original 
 freshness ; and it is even asserted that, after having lain 
 in the herbarium for some years, when they are replaced in 
 water in a suitable locality, that they will vegetate as before. 
 
 The manner in which the glomerules are developed does 
 not seem to be well understood * ; each would appear to be 
 compounded of numerous cells, all having a single and 
 common attachment to the parent plant by means of a single 
 and slender thread ; from which they, when mature, separate, 
 
 * In the earliest period of their development they would appear to be 
 minute excrescences growing out of the walls of the cells, from which 
 finally they become entirely separated in most of the species of the genus, 
 but not in all, as in B. cdnim. 
 
BATRACnOSPERMUM. 103 
 
 or are tlirown off. They would appear to partake more of the 
 natui'e of buds than seeds. When developing, each emits 
 numerous branches, Avhich radiate in all directions. 
 
 Bory would seem to be the only observer who has studied 
 the species of this genus with that nice discrimination which 
 they require: in associating Batrachospermum atrum, however, 
 and some other species with the genus Thorca, he has 
 committed a great error. By a careful comparison of speci- 
 mens derived fiom the herbarium of Dillenius, which are 
 in the collection of M. de Jussieu, with others collected by 
 Roth, ]\Iertens, and Draparnaud, Bory has succeeded in 
 ascertaining the correct synonymes of several species or varie- 
 ties, which had previously been quoted indiscriminately. 
 
 From the great number of specimens described in the 
 following pages, there are some, I fear, who will be dis- 
 posed to think that they have been multli^lied on insuf- 
 ficient grounds: such an opinion I ani sure will not be 
 entertained by those who have carefully studied the genus 
 for themselves, and who have had opportunities, as mainly 
 through the liberality of friends I have had, of comparing 
 a considerable number of specimens collected from widely 
 different localities together. 
 
 I suspect that the species of tliis genus are propagated 
 not merely by gemmo3 or glomerules, but also by Zoospores, 
 contained as in other Algcs zoospo7-(B in the cells, of the 
 aggregation of which these plants are composed. 
 
 The affinities of the genus are by no means direct, in their 
 lubricitj^, in the presence of cilia, and probably in tlieir 
 reproduction by zoospores they bear a certain relationship 
 to the family ChcBtophorccu. 
 
 a. Filaments exceedingly jlexihle. 
 
 1. Batrachospermum bombusinum Borg. 
 
 Plate XIII. Fig. 3. 
 
 Char. Frond delicate, filaments sparingly branched, branches 
 simple. Cells much elongated. Vcrticilli minute, distant. 
 
 H 4 
 
104 BATRACHOSPEKME^. 
 
 ** Batrachosperma (bomhusina) Jilamentis ramosis ; articiilis 
 elongatis ; vcrticillis minutissimis, distantibus conoideis.'''' 
 — Boiy de St. Vincent, Annales du Museum, vol. xii. 
 
 Hah. Malahide near Dublin : Dr. Coulter. 
 
 " This beautiful plant grows in the Isles of France and of 
 Re-union. It covers pebbles in places exposed to the cur- 
 rents of great rivulets, particularly at the Great River and 
 the river of Saint Denis. 
 
 " Its colour is of the most elegant green ; but if the speci- 
 mens of this plant be not quickly j^repared, they very soon 
 turn black upon the paper. 
 
 " From a principal filament from two to four inches long, 
 proceed many long slender loose branches, simple, or having 
 sometimes here and there scattered very small branches, 
 which are never divided. The articulations of the principal 
 stem, and of the larger branches are for the most part naked ; 
 their point of contact is dilated in such a manner as to 
 resemble the rods of bamboos. 
 
 '' As to the verticilli, they are rounded, smaller than those 
 of the folloAving species, composed of very compact branch- 
 lets. Their simple ramuli are likewise shorter than in the 
 other Batrachosjyerms ; three or four rounded joints compose 
 them : the ciliform appendage which terminates them is re- 
 markable. Some ramuli, shorter than those of the verti- 
 cillum, cover also the inferior part of the articulations, which 
 have the appearance of reversed cones." — Bory. 
 
 Bory's descriptions and figures of this species are so ac- 
 curate, as to leave no doubt either as to Its specific distinct- 
 ness, or its identity with the plant collected by Dr. Coulter. 
 
 The exact correspondence of the specimens collected in the 
 Isles of France and of Re-union is remarkable with those found 
 in Ireland, and helps to confirm the opinion which I have 
 long entertained that the difl:erent species of the freshwater 
 division of the Algce are almost universally diffused. 
 
BATKACIIOSPERMUM. 105 
 
 2. Batrachospermum HELMINTOSUM Bory. 
 Char. Filaments branched, j)yramidal, naked helotc ; branches 
 simple, siihpinnate, acute. Verticllli contiguous, com- 
 pressed. 
 
 Boiy, in Annalcsdu Museum, vol. xii. p. 316, pi. 29. fig. 2.; 
 Corallinapinguis, ramosa viridis, Vaill. Paris, 4to. tab. vi. 
 fig. 6. 
 
 Hah. New River, Cheshunt : A. H. H. 
 
 " There is no doubt but that Vaillant's plant is also 
 oiu' plant : the figure which he has given of it is inferior ; 
 the disposition of the branches is badly given ; but the 
 tubercles in it are confounded. The extremities are subu- 
 late, and the author compares his corallina to a muscus Jili- 
 cinus. I have moreover gathered the species in question in 
 the place in which the Parisian botanist has pointed out for 
 his habitat. I then discovered it for the first time upon the 
 rocks in the gloomy bosoms of very many freshwater foun- 
 tains situated in Brittany, beside the river Goesue, near the 
 city of Fougere. 
 
 " The stems of this beautiful species scarcely exceed two 
 inches in length. They are fine, and denuded at their base, 
 which appears yellow. Numerous branches proceed from it : 
 they are somewhat subulate, and diminish in length, in such 
 a way, that they incline from the extremities of the plant, 
 which gives to it a pyramidal ai^pearance. 
 
 " The verticilli are compressed, voluminous, horizontal, and 
 so aj^proximated, that they cannot acquire the globular form : 
 they become confused, and form around the stems a continuous 
 cylinder of mucosity. The diameter of this cylinder equals 
 often that of tlie plume of a httle bird. The branches are 
 not less thick at their insertion. The colour of the plant is 
 obscure, of a bluish and uncertain green." 
 
 3. Batrachospermum confusdm JIass. 
 
 Plate XV. Fig. 1. 
 
 Char. Frond large. Filaments much branched. Verticilli 
 contiguous, subconfuscd, compressed above arid below. 
 
106 BATRACHOSPERME^. 
 
 Conf. gelatinosa Dillw. Brit. Conf. Bat. ludihundiim (var. 
 confusuni) Bory, in Annalesdu Museum, vol.xiv. p. 320. 
 pi. 29. fig. 3. no. 63. ; Gir. Clmntrans. Mycros. p.?,175. 
 pi. 25. 
 
 Hob. Lea -well, Devonshire : IV. H. Harvey. In a 
 small brook in Clive AVood, Swansea : Dilho. 
 
 Under the name of BatracJwspermum ludihundiim Bory de- 
 scribes seven different varieties oi Batrachospermum : many'of 
 these are indigenous to Great Britain, and several of them 
 doubtless, are distinct species, in which light the plant under 
 consideration ought to be regarded. 
 
 " This variety is not rare ; it grows in the closed basins of 
 very pure and cold fountains. It there appears to choose 
 shady places. It is found in the holes of rivers, Avhose waters 
 carry no mud. I have observed it in France, in Spain, in 
 Germany, in Poland, and in Ducal Prussia. 
 
 " Of all BatracJiosperms, this acquii'es the greatest dimen- 
 sions : its length is sometimes four inches and a half, its dia- 
 meter equal often to that of the culm of grasses. Its branches 
 ai^pear also to be less obtuse than in the following varieties. 
 The globules or whorls are so approximated and so large 
 that they are often confounded together in such a manner, 
 as to be with difficulty distinguished in certain specimens 
 which have the aspect of Batrachosperma helmintosa. The 
 colour of the plant is of a mouse grey, agreeable by its trans- 
 parency. The large stems approach a little upon yellow. 
 These tints become of a beautiful violet by putrefaction. 
 
 " It is upon individuals of the variety which now engages 
 us that I made, for the first time, twelve years ago, an experi- 
 ment which ought to be known ; after having many times car- 
 ried from one locality to another stones bearing individuals of 
 tliis species, which continued to prosper in spite of the change 
 of habitation, I steeped many of them in lukewarm water, 
 afterwards in boiling, and no part of the hatracliosperm ap- 
 peared, under the microscope, to have undergone the slightest 
 disorganization by these immersions, and certain sj)rigs replaced 
 in their native jolace continued to vegetate after these experi- 
 
BATRACnOSPERMUM. 107 
 
 raents. I do not think that there exist other vegetables which 
 boiling water does not immediately disorganize ; there are not 
 others that can resist temperatures so opposite." — Bory. 
 
 This species differs from Batraclwspcrmum hclmintosum by 
 its stems, which are never denuded below, but always verticil- 
 late, and by its branches, which are more obtuse, less thick at 
 their insertion, and furnished with many secondary branchlets. 
 I am not certain however that the B. hdmintosum is anything 
 more than a variety, which the following may be also. 
 
 4. Batrachospermum stagnale Hass. 
 
 Char. Frond yclloioish green. Filaments thick, branched. 
 Whorls, distinct, slightly comjjresscd, in the trunk confused. 
 
 BatrachosiJcrmum ludibundum (stagnale^ Bory, Annales du 
 Museum, vol. xii. p. 325. pi. 30. fig. 5. Conferva fon- 
 tana, nodosa ; sjjei'jyiatis ranarum instar luhrica minor et 
 viridis. Dill. Muse, vol. xvii. f. 44. Conf. stagjialis, 
 globidis viridis, centihus mucosis. Chara hatrachosperma 
 Weiss, Plant. Crypt. 
 
 Hab. Cheshunt, Herts : A. H. IL 
 
 "Both (Cat. Bot. i. 126. No. 11. 187.) referred this last 
 synonyme of Dillenius to a variety (/3) o^ Batrachospermum mo- 
 niliforme: he has since regarded tliis variety (Cat. Bot. iii.161.) 
 as appertaining to his Corferva mutahilis, which is one of our 
 DraparnaldicB ; but certainly the figure cited by Dillenius and 
 his phrase applies perfectly to the Batrachosperm which is 
 here under consideration, and cannot be applied to any other 
 plant. The rounded and very distinct globules, which the 
 English author represents, have no kind of resemblance to the 
 scattered tufts of the Conferva mutahilis of the German natu- 
 ralist. As to the figure 43. of the ' Illstorla Muscorum,' there 
 is no doubt that it represents the same plant as the figure 44. 
 There is absolutely no difference but in the length of the 
 branches, which proceeds from the age of the specimens repre- 
 sented. The stagnant variety of Batrachospermum ludi- 
 bundum has great resemblance in form and diameter to 
 
108 BATRACHOSPERME^. 
 
 Batraclwspermum confusum ; it is nevertheless shorter, but as 
 thick. Its Avhorls are round and distinct ; they are more ap- 
 proximated the one to the other in the large stems, about 
 which they are sometimes even confused. Their colour is a 
 greenish yellow, pale, and livid. 
 
 " This plant is found in ditches and in the most tranquil 
 fountains. I have even seen it in marshes fixed against 
 scirpes and stakes." 
 
 5. Batrachospermum moniliforme Hass. 
 
 Char. Frond blackish brown. Whorls of the stems, distinct, 
 spherical, in the branches confused. 
 Batrachospermum ludibuiidum {inoniliforme^ Bory, in loc. 
 cit. xii. p. 322. pi. 30. fig. 1. Conf. fontana, nodosa, sper- 
 viatis ranarum instar luhrica major ct fusca. Dill. Muse, 
 p. 36. t. vii. fig. 42. Chara {gelatinosa frondibus gela- 
 tinosis Jilamentosis : Jilamentis capillaribus tenuissimis. 
 Verticillis approximatis moniliformibus, Roth. Cat. i. 125. 
 Batrachospermum (nioniliforme) Jilis ramosis ; ramis al- 
 ternis polle7itibus, 8fc., Roth. Cat. Bot. iii. 160. Batra^ 
 chospermum moniliforme Vauch. Conf. 112. t. 1. fig. 5. 
 et tab. ix. fig. 4. 
 
 Hab. Plassey, near Limerick : W. H, Harvey. Upland 
 mountainous district 14 miles west of Aberdeen: Dr. 
 Dickie. Gal way: M'Colla. Hill of Fare: Dr. Dickie. 
 
 " This variety is the commonest of all. It is frequently 
 met with in fountains, in rapid rivers, and even in waters 
 almost stagnant ; it is sufficient that they are pure. It 
 has some resemblance to the variety B. corfusum; but it 
 is more slender, and its bearing is more elegant. Its stems 
 are very much divided, and from one to three inches long ; 
 the globules which cover them are round, distinct, and appear 
 to hold each other only by their poles. They are, however, 
 confused in the last branches, which resemble little worms. 
 
 *' The colour of the B. moniliforme is deeper than that of 
 
BATRACnOSPERMUM. 109 
 
 B. confiisum ; it is also more solid, and changes less in dying : 
 it takes nevertheless sometimes a tint of pale violet or a 
 livid yello\y." 
 
 6. BaTRACHOSPERMUM PULCHERRIMUM Ilass. 
 
 Plate XIV. Fig. 1. 
 
 Char. Frond violet grey. Whorls spherical, distant, distinct 
 
 in the stems and branches. 
 Bory, in Annales du Museum, xii. 323. PI. 30. fig. 2. 
 Hah. Stream near Cheshunt : A. 11. H. Near Tunbrigde 
 
 Wells : Mr. Jenner. 
 
 " The extreme elegance of form and of colour renders 
 this Batrachosj^ei-m remarkable ; its stems are rather more 
 branched than those of the variety (a) B confusum, and less 
 than those of (7) B. moniliforme, are from two to three inches 
 and a half long, slender, and of an intermediate diameter. 
 The globules arc perfectly spherical, distant upon the stems 
 from each other the length of a ray, more approximate, flat- 
 tened, but always distinct in the branches. 
 
 " Its colour is a clear grey, approaching to a most agree- 
 able violet. This last tint becomes dominant in drying, and 
 passes sometimes to red." 
 
 This description applies closely to the plant, Avhich I have 
 twice met with, in all respects save colour, my specimens 
 when recent being of a pleasant green, which in drying be- 
 came blackish — a tint which the specimens Avhich I received 
 from ISIr. Jenner likewise presented, and yet I can scarcely 
 consider them other than the Batrachospermum ludihmdum 
 {var. pulchei'rimiun) of Bory. 
 
 7. BATRACH0SPER3IUM VAGUM Ag. 
 
 Plate LXIII. Fig. 2. 
 
 Char. Filaments suhdichotomons, much branched, evcrgu-here 
 covered. Whorls horizontal, compressed, indistinctly con- 
 fused. 
 
110 BATRACHOSPERME^. 
 
 Batrachos'permum turfosum Boiy, in Annales du Museum, 
 loc. cit. Conferva gclatinosa var. vaga Roth, Bot. 
 i. 127. Batrachosperimim moniliforme var. (S) vagian 
 Roth, Fl. Germ. iii. 482. 
 
 Hah. Appin : Captain Carmichael. Summit of Snowclon ; 
 Sir TF. J. Hooker. Loch Phadrich, 2199 feet above the 
 level of the sea, Aberdeenshire, August, 1842: Dr. 
 Dickie. Frequent in Ireland : D. Moore. Cromaglau : 
 W.H.Harvey. Gal way : M^Colla. In the stream by 
 the v^^all near the entrance of the park by the road-side 
 from Rackham to Pulborougli : E. Jenner. 
 
 " M. There, naturalist of Dax, first discovered this p»lant 
 in the environs of the city which he inhabits. I have 
 since met with it in peat holes of our southerly lands in 
 places where the water, although coloured, is pure ; it there 
 grows always at a certain deptli, and rarely less than from 
 two to three feet. 
 
 " In no other Conferva is the number of the filaments so 
 considerable as in this. Their total diameter equals that of 
 the largest horsehair. They divide in every direction from 
 a little disc, ramify to infinity, observing remarkably well 
 the dichotomous disposition in their first division, their 
 branches becoming subsequently vague. Their total length 
 extends even to four inches. 
 
 " From their origin, even to their extremity, these filaments 
 are clothed with microscopic branches, so impacted that the 
 whorls are not apparent in scarcely any direction : wath a 
 simple lens they are not better discovered, from which it 
 might be suj^posed that one was observing a Thorea. It is 
 but towards the points of the branches that, by the assistance 
 of a strong lens, they are at last distinguished. These whorls 
 are very closely approximated, horizontal, compressed the 
 one upon the other, and becoming so confused as to form 
 around the filament, which is green or yellow, and very 
 flexiljlc, a continuous down, mucous to the touch, sometimes 
 very pale, more frequently of a very agreeable bluish watery 
 green : this colour is moreover deep towards the point of the 
 
BATRACIIOSrERHrUM. Ill 
 
 branches. As it grows old the plant turns yellow and is 
 discoloured." 
 
 The apices of the branches in young specimens are often 
 dilated, and all the filaments present in this state a greater 
 diameter, and a deeper colour, being usually glaucous green. 
 
 Some specimens of what I regard as a variety of this 
 species were sent rac by Dr. Dickie. They differed from the 
 species in its ordinary condition in the fact of the lower whorls 
 of the main stems being distinctly moniliform. 
 
 8. BATRACnOSPERMUM ALPESTRE Shut 
 
 Plate XIV. Fig. 2. 
 
 Char. Frond black, very mucous, much hrancJied ; alternatelij 
 forming very obtuse angles with the ■principal filaments. 
 Whorls of the stems spherical, distinct, but approxirnatc, 
 branches compressed. 
 Batrachospermum alpestre, Shuttleworth's ISIS. 
 
 Hah. River Lea, Cheshunt : A. II. H. Ireland : W. H. 
 Harvey. 
 
 It is now some three or four years since I first encountered 
 this species, from which time I regarded it as distinct from 
 any described British Batraclwspcrmum, an opinion Avhich 
 I was happy to have confirmed recently by the receipt of 
 a specimen marked B. alpcstre Slmttleworth, and which 
 exactly accords Avith my own in all respects, except in being 
 much smaller. At the same time, JNIr. Harvey, to whom 
 I was indebted for the authentic specimen of B. alpcstre, 
 sent me a second example collected by himself, with the ob- 
 servation affixed to it, "very like B. alpcstre, but I have 
 not examined it." 
 
 This species is easily recognised by the eye alone, either 
 in its recent or dried state ; in the former its size, great 
 lubricity, jetty black colour, and approximate, yet for the most 
 part exactly spherical whorls, are remarkable ; in the latter, 
 in which also the black tint is preserved, it may be distinguished 
 by the multiplicity of its branches, which are, except the pri- 
 
112 BATRACHOSPERME.E. 
 
 mary ones, exceedingly short and irregular, and issue from 
 tbe main filaments almost at right angles, and by their non- 
 moniliform aj:)pearance. In drying, also, it shrinks consider- 
 ably. It is a Avell marked, but apparently not an uncommon 
 species. I am not able to refer it to any described by Bory. 
 My specimens were met with during the summer in a rapid 
 part of the river Lea, near Waltham Abbey, attached 
 to piles of wood, which they almost covered. The length 
 of some of them reached to four inches ; their great size, 
 the elegance of their movements, and their dark colour, 
 at once struck me, and made me desirous of secm'ing speci- 
 mens, which it was not easy to do in consequence of the 
 depth at which they grew. I succeeded, however, in obtain- 
 ing a few at the imminent risk of immersion. 
 
 9. Batrachospeemum proliferum Hass. 
 
 Plate LXIII. Fig. 1. 
 
 Char. Frond grey, branches irregular, divaricate, beset 
 loith short ramuli, lohich are innnate. Whorls of the 
 stems ajjproximate, compressed, almost confused, in the 
 pinnate branches, subdistant, distinct, formed of very few 
 filaments. 
 
 Batrachospermum moniliforme, B. proUferum, Carmichael. 
 
 Hab. Appin : Captain Carmichael. 
 
 I have seen but one specimen of this curious and in- 
 teresting siDecies, for an examination of which I was in- 
 debted to Mr. Harvey : not the slightest doubt, however, 
 remains on my mind of its distinctness; it is certainly no 
 less distinct than rare. Captain Carmichael, to whom algolo- 
 gists are deeply indebted, for numerous additions to both 
 the marine and freshwater divisions of the Algce., and whose 
 powers of observation were of a very high order, thus In his 
 MS. describes the plant in question. " Fi'ond. solitary or 
 in small clusters, one or two inches long, irregularly branched; 
 branches divaricate, curved or flexuous, opaque and very 
 dark coloured, beset with short ramuli, Avhich issue out from 
 
BATRACnOSrERMUM. 113 
 
 the joints among the -wliovls of eccentric filaments, and are 
 themselves beset with whorls ; colour grey." 
 
 10. Batrachospermum rubrum Ilass. 
 riate XV. Figs. 2, 3. 
 
 Cliar. Filaments much hranclied. Branches divaricate, alter- 
 nate, ramali broad, expanded. Whorls of the stems sphe- 
 rical, distinct, subdistant, large, those of the branches 
 altogether confused. 
 Batrachospermum moniliforme var., Penzance, June, 1839 : 
 Mr. Ralfs. 
 
 This is one of the most curious, as well as distinct species 
 of the genus. I Iiave seen but a single specimen of the 
 plant, but this is quite sufficient to establish it as a species. 
 This specimen was sent to me, amongst other good things, by 
 my friend ISIr. Harvey, and belongs to the Herbarium of 
 Trinity College, Dublin, to which ]\Ir. Harvey, I believe, 
 has generously presented the whole of his collection of Algce. 
 J3atrachospermu7n rubrum might possibly be mistaken for 
 Thorca ramosissima, on account of its mode of ramification, its 
 colour, which is bright red, and, above all, the expanded 
 branches, which are so like those of T. raynosissima, that if 
 it were not for the whorls on the main stems, the species 
 might readily be referred to the genus Thorea, an error 
 which even a microscopic examination of the plant would not 
 at once remove. If one of the whorls be submitted to the 
 microscope, it will be found to be composed, in part, of 
 slender filaments slightly beaded, and, in part, of other still 
 inoi*e slender threads, which are cylindrical, and from which 
 the first set of filaments would appear to arise, and both of 
 which are mixed together ; and again, if a portion of one of 
 the branches be examined from which the whorls have dis- 
 appeared, it will be seen to be composed almost entirely of the 
 exceedingly minute, and occasionally branched threads, with 
 here and there attached to them a single pyriform cell (see 
 fig. 3)., which is to be regarded cither as the rudiment of the 
 
114 BATRACnOSPERMEiE. 
 
 ordinary beaded threads of which the branches are composed, 
 or as a capsule, but probably the former. It is thus seen 
 that this species is remarkable both in appearance and struc- 
 ture. 
 
 11. Batrachospermum atrum Harv. 
 
 Plate XVI. Fig. 1^. 
 
 Char. Filaments very much ramified. Whorls distiiicf, distant^ 
 short, in the form of reversed cones, opaque ; inferior 
 portion of the articidations pellucid. 
 Lemania {batrachospermum) filamentis ramosissimis elon- 
 gatis ; nodis superne incrassato opacis, ijfcrne alternatis 
 pellucidis, Bory, in Annales du Museum, xii. 188. Ba- 
 trachospermum moniliforme (^) detersum Ag., Hook. 
 Brit. Floi'. Batracliospermum atrum Harv. in Manual, 
 p. 120. Conf atra, E. B. t. 690. 
 
 This species is, perhaps, the most elegant of the genus ; it 
 grows generally in still, though pure waters. Although placed 
 by Bory in his genus Lemania, it cannot be said to have 
 any near structural relation thereto. 
 
 The articulations or internodes may be compared to re- 
 versed cones, the superior jiart or whorls being formed of a 
 few short, simple, subulate filaments, which are not beaded : 
 in these filaments the colouring matter cliiefly resides, and it 
 is amongst them that the glomerules are formed : that portion 
 of each articulation, which is below the whorl, is transparent, 
 and beautifully exhibits the tubular and jointed structure of 
 the layers which invest the 2)rimary cells in all the species of 
 the genus Bcdrachospermum ; from many of these tubes, short 
 branches are given off, which have almost the appearance of 
 scales. 
 
 It is probable that there are several varieties of this species 
 wdiich have all been confounded together. Bory describes 
 two, both of which, I believe, I have recognised. 
 
 a. SETACEUM. — Filament slender, long, carulescent. — 
 Bory, in Annales du Museum, xii. 188. pL xxii. 
 fiff. 3. 
 
RATRACHOSPERMUM. 115 
 
 Chantransia atra, nigrescens, filamcntis ramosis tenuis- 
 simis ; articulis longis teretihus ; gcniculis, suhrotundis 
 ciliatis, Cand. Syn. No. 120. Chantransie noir^ 
 Cand. Flor. fr. 2. 120. 
 
 Hah, Ferrlng, near Arundel : Mr. Jennet. 
 
 " The filaments of this variety are exceedingly fine, and 
 often almost imperceptible. They dispose themselves with 
 grace upon paper; their internodes are a little oblong, and 
 less inflated towards their superior part than in the following 
 variety." — Borg. 
 
 /3. CAPALLINUM? — Filaments somewhat thick, hlach. — 
 Bory, in loc. cit. pi. xxii. fig. 4. 
 Hah. Cheshunt Marshes : A. H. H. 
 
 " The filaments of this variety are of the size of Chora, a 
 little shorter than those of the preceding ; they appear firmer 
 and blacker. 
 
 *' It dwells frequently with the large varieties of Conferva 
 gelatinosa of Linna3us, and appears to love to entwine itself 
 with it." — Borg. 
 
 " I have bestowed nearly all my attention upon our native Swiss 
 Plants ; for I had to pursue, at the same time, anatomy and the practice 
 of Physick : being unlike you the consecrated priest of Flora. I have 
 always cultivated Botany, in spite of all obstacles, since the year 17'2S, 
 when I accomplished a laborious journey of 200 leagues through the 
 Alps, on foot. I have since visited those mountains ten successive 
 times. But I am near-sighted, which is a great inconvenience. I have 
 laboured much at Mosses and such plants. I hope to settle a good many 
 doubtful matters, though many must remain undetermined. My family 
 are always finding fault M'ith my pursuit ; but I do not repent. On the 
 contrary, I regret that I did not devote more of my time to these 
 things." 
 
 " Farewell my dear Linna;us, may you enjoy your health and your 
 botanical pursuits with every advantage for the prosecution of your 
 labours ! IVIy studies and engagements, of a difterent kind, draw me un- 
 avoidably aside ; but my inclination always leads me to the charms of 
 Flora. To Botany I wish to devote my leisure, my old age, and my for- 
 tune." — Haller to Linnaus. 
 
 I 2 
 
116 
 
 Fa^i. VII. CH^TOPHOREiE. 
 
 Char. Algse gelatinous, ramose, composed of ])rincij)al stems 
 and smaller filaments, for the most part ciliated. Re- 
 production usually by means of zoospores contained in the 
 filaments, hut in some cases said to he capsular. 
 
 The species of this very natural family accord with the 
 preceding in being composed of two sets of filaments, in their 
 extreme lubricity, and in their branches terminating in long 
 ciliform appendages, to which, in a measure, their great 
 lubricity is attributable. They differ from it, however, in 
 the secondary branches not being whorled, in the absence of 
 glomerules, and of the fibrillas surrounding the primary cells, 
 also in being of a light and beautiful green colour, which, 
 in drying, does not change to some other tint, as has been 
 seen to be the case in the Batrachospermea. 
 
 The two families, likewise, agree in habit, the ChcBto- 
 phoretB, like the BatrachospermecB, dwelling in fresh and pure 
 water, such as that of fountains and slow streams ; but on 
 account of the delicacy of their structure they are not met with 
 in large rivers or streams, the force of whose current is 
 strong, and which would sweep them away and destroy them. 
 
 On certain species of the genus Cliatophora capsules have, 
 from time to time, been met with, but the occurrence of these 
 is exceedingly rare, and it cannot be supposed that the ordi- 
 nary and usual mode of I'eproduction is by means of these. 
 The true reproductive bodies in this family, as well in all 
 probability as in that of the Batrachospermea, are undoubt- 
 edly zoospores. If a specimen of Draparnaldia, D. cjlomerata 
 for example, be examined microscopically in its young state, 
 the main filaments will be seen to be quite cylindrical : at a 
 later period, however, the cells, of Avhich these filaments are 
 composed, swell up, and the filaments then become beaded. 
 This inflation of the cells, which occurs in almost all the 
 
CHiETOPnOREiE. 117 
 
 branched Algcs, is indiccativc of the period of reproduction, 
 and terminates in the rupture of the individual cells, the 
 zoospores escaping through the apertures thus provided. 
 That this is the usual and true method of reproduction it is 
 easy to satisfy oneself in the following method. If a specimen 
 of Draparnaldia glomerata be kept in water, which ought not 
 to be renewed for a day or two, the cells will be observed to 
 separate from each other, and, floating on the surface of the 
 fluid, will be noticed a greenish pellicle : if a portion of this 
 be placed beneath the microscope, it will ]3C found to consist 
 of a slimy material, in which are contained numerous green 
 globules of very minute size ; these, if watched for a day or 
 two, will be seen to take on the characters peculiar to the 
 species. 
 
 The following observations in M. Decaisne's Memoir on 
 the Classification of the Alga in the Annales des Sciences 
 Naturelles occur, wliich correspond closely Avith the views 
 already expressed in reference to the reproduction of the 
 genus Draparnaldia, and which I have long entertained. 
 
 " The Draparnaldia glomerata is composed, as it is known, 
 of a principal trunk formed by a scries of large cells placed 
 upon each other, transjjarent, each occupied Avith a ring of 
 green matter, rather pale, mucous, and mixed up Avitli ani}-- 
 laceous globules. Tlie branches, Avhich arise from the points 
 of junction of these cells, are themselves composed of articu- 
 lated ramuli, and terminated by a conferA'oid ciliform thread, 
 Avhich, all united, produce the mucilage Avith Avhich the plant 
 is found enveloped. 
 
 " At tlie period Avhen it lias attained its complete develope- 
 ment, the hairs are seen to detach themselves successively 
 from the last joint : afterwards the green substance enclosed 
 in each of the ramuli unites into little globules, Avhich escape 
 one after the other by a rounded aperture *pratiquees' upon 
 each of the cellules. These themselves become absorbed {se 
 resorbent) as soon as tliey are empty, so that at a period 
 more advanced, one finds of all the plant but a single filament 
 enA^clopcd with mucus and filled Avith green globules. 
 
 " I bcHcve that I am able to conclude from these observ- 
 I 3 
 
118 CH^TOPHOEE^. 
 
 atlons that each of the cells of Draparjialdia glomerata ought 
 to be considered as a receptacle whence the reproductive 
 bodies formed at the expense of the green matter issue under 
 the form of rounded vesicles themselves being fiUed with 
 endochrome." — M. Decaisne, Memoire sur la Classification 
 des AlgueSf p. 314. 
 
 8. DRAPARNALDIA Bory. 
 
 Char. Filaments /ree, not immersed in gelatinous fiuid. 
 Draparnaldia Bory, in Annales du IMuseum, voL xii. 
 Charospermum Link, in Hort. Phjs. 5. Batrachosper- 
 mum in part, Vauch. Hist, des Conf. 
 
 " It is to Draparnard that I dedicate this genus, which 
 forms the subject of this new memoir. Those who have 
 been acquainted with that naturalist, alone know all that 
 he was capable of: active, indefatigable, he was fitted for 
 studies the most diverse. Wise and prudent, also timid in 
 his researches, he hastened not to pubhsh ; he collected facts, 
 he matured them, he wished his works to be without re- 
 proach. INlisfortunes and death have surprised him before 
 the execution of his projects, his career is closed before his 
 writings have established his reputation. Scarcely a few 
 phrases, escaped from his pen, and committed to paper, re- 
 main ; and the loss of treasures which he had collected in 
 his memoirs occasions the greater regret to those who loved 
 him for cherishing the sciences as he cherished them. 
 
 " I could doubtless have selected, amongst so many rare and 
 new vegetables which presented themselves to me in my 
 voyages, — I could have found, I say, some genus more ana- 
 logous to the beauties of his spirit, upon which to place the 
 name of Draparnard; majestic palm trees, brilliant with 
 vigour, reigning over the forest, should perpetuate his remem- 
 brance. But the modest manes of my friend, have they not 
 approved my choice ? They will smile on that which I have 
 done. May his name live amongst the Conferva, which Avere 
 his dearest study !" — Bory. 
 
 Kiitzing refers the genus Draparnaldia to his Ectospermca, 
 
DRAPARNALDIA. 119 
 
 placing it immediately before Ectocarpus, and of course 
 assigning to it lateral external fructification. Certain 
 species hitherto associated with the genus Draparnaldia 
 Kiitzing has removed therefrom ; these are D. stcUaris, 
 which may be identical with my Z>. condensata, and D. tenuis^ 
 and constituted a new genus for them, under the name of 
 Stygeoclonium : this genus is not even placed in the same family 
 with Drapai'naldia, but in that of UlothricecB, of which Lyng- 
 hya zonata forms the type. The following are the definitions 
 of the family and genus. 
 
 " UlothricecB. 
 " Trichomata mucosa teuerrima, ceUulsc coleogonimica9, sub- 
 stantia gonimica in fascias transversales disposita, postremo in 
 opseospermata hologonimica plerumque quadripartita trans- 
 iens." 
 
 " Stygeoclonium Ktz. 
 
 " Trichoma tenerrimum, ramosum, ramulis simplicibus 
 subulatis obsessum ; cellular gclineaa tenuissimw, abbreviataj ; 
 amylcdiaj in fasciam transversalem collapsre, tandem in opseo- 
 spermata quaternata turgida transeuntes." 
 
 I cannot myself think that any essential difference exists 
 between the reproduction of Draparnaldia tenuis, &c. and 
 other DraparnaldicB. I have myself occasionally observed the 
 quaternary division of the endochrome in the smaller branches 
 of, I believe, all the species o^ Drapai-naldicB : the circumstance 
 of the occurrence of this disposition in certain species of the 
 genus more frequently than others does not seem to me 
 to call for their separation from that genus altogether ; yet 
 Kiitzing has not merely formed a new genus for them, but 
 has referred this genus to a distinct family, — a family which 
 docs indeed manifest a close aflSnity with Draparnaldia, but 
 which Kiitzing places in his arrangement at some distance 
 therefrom. The genus Lynghya, of which L. zonata forms the 
 type of the ftuiiily JJhthricece, accords Avith Draparnaldia in 
 the extreme mucosity and flexiljility of its filaments, in pos- 
 sessing the second mode of growth of the cells, viz. that of 
 lateral dcvelopemcnt, in the endochrome being arranged in 
 
120 CHiETOPIIORE^. 
 
 bands across the cells, and essentially in its reproduction. The 
 only real difference between the genera consists in the filaments 
 of the one being simple and those of the other branched. In 
 an arrangement, therefore, in wliich affinities are studied, 
 these two genera should be placed near to each other. 
 
 1. DrAPARNALDIA GL03IERATA Aff. 
 
 PI. XIII. Fig. 1. 
 
 Cha?'. Stem rou7id, branched. Ramuli in tuffs, ivltich are 
 
 frequently alternate a?id ahoays ciliated. Tufts divergent. 
 
 Hah. Everywhere common in slow streams and ditches, 
 
 adhering to stones, sticks, &:c. 
 Draparnaldia (jnutahilis) gelatinosa ; filamentis crassiusculis ; 
 ramis suhjnnnatis, ohtusiuscidis ; fasciculis hreviusculis, 
 comjjlicatis, Bory, in Annales du Museum, pi. 35. fig. 1 . 
 Conferva mutahilis Roth, Cat. Bot. i. 197. Flor. Germ. 
 iii. 518. C. mutahilis Roth, Cat. Bot. iii. 282. C. fas- 
 ciculata Thore, Chlor. 444. Batrachosperme en houpe, 
 Vauch. Conf. 114. pi. xii. fig. 4. et 5. ; Cand. Flor. 
 Fr. ii. 6*^. Batrachospcrmum glomeratum Cand. Syn.144. 
 C. mutahilis, Eng. Bot. t. 1470. D. glomerata Harvey, 
 in Hook. Brit. Fl. p. 388. ; in Manual, p. 121. 
 
 This species differs in appearance greatly according to its 
 age and place of growth. The younger specimens are of a 
 herbaceous and delicate green, abundantly branched, and the 
 older ones often nearly denuded of branches and almost colour- 
 less, becoming so by the escape of the zoospores. When dried 
 on paper the differences between certain specimens of this 
 plant presented to the eye are so considerable that many 
 would regard them as varieties, and almost as species. A 
 microscopic examination would, however, at once remove 
 this supposition. 
 
 When first removed from the water, it presents the appear- 
 ance of a mass of coloured jelly without form or organization : 
 on immersion, however, its branches soon expand. Its fragility 
 is so excessive, that frequently its own weight when fresh is 
 
DR APARNALDI A. 121 
 
 sufficient to break It, and it is often a matter of considerable 
 difficulty to remove a specimen entire from tlie water for 
 preservation, each frond breaking as soon as tlie hand is placed 
 beneath it, and its own gravity is felt, and dividing into 
 many separate pieces, which are slowly carried away by the 
 gentle stream in which the species is usually found. It ad- 
 heres closely to paper, and does not undergo any considerable 
 change of colour in drying, it also recovers like the Batra- 
 chospermea much of its freshness on being moistened. These 
 last remarks apply to all the species of the genera Drapar- 
 naldia and Chcctophoi^a. 
 
 2. DllAPAKNALDIA PLUMOSA A(/. 
 
 Plate XII. Fig. 1. 
 
 Cha?'. Frond subgelatinous. Filaments gracile, elongated. 
 Branches subphmate. Tufts elongated, scattered, op- 
 proximate to the branches, ciliated. 
 .Batrachosjyerme cii plume, Vauch. Conf. 113. pi. xi. fig. 
 2. and 4. ; Cand. Fl. Fr. ii. 59. Batraclwsjjermwn plu- 
 mosum, truncis elongatis ; ramulis cauli approximatis, 
 Cand. Syn. 143. Droparnaldia hypnosa Bory, in An- 
 nales du Museum, 405. pi. 35. fig. 2. D. plumosa Har- 
 vey, in Hook. Br. Fl. ; in Manual, 121. Conf. lubrica, 
 E. B. t. 2087. 
 Hob. Galway: M'Colla. Aberdeen: Dr. Dickie. ]\Ied- 
 hurst and Eastbourn : Mr. Jenner. Stream near Hod- 
 desdon : A. H. H. 
 
 This species is more slender, less gelatinous, and attains 
 a much greater length than Draparnaldia glomerata. It 
 lives also in purer and deeper water, is usually of a brighter 
 and more beautiful green, and, from being less gelatinous, 
 it is also less fragile. The mode of branching is different in 
 the two species; the tufts in that which is here described 
 are longer, more scattered, approximated to the branches, and 
 not as in the previous species divergent. It is an elegant 
 species. The cells of the stems are usually shorter, and rarely 
 so inflated or oval as those of D. glomerata. 
 
122 CHiETOniOREiE. 
 
 3. Draparnaldia repetita Hass. 
 Plate XII. Fig. 2. 
 
 Char. Filaments branched, consisting of repeated series of cells, 
 each series composed of Jive or six cells, which decrease in 
 size from the first or loioer cell to the last or upper one, 
 Tufts dense, alternate. 
 
 Hassall, in Annals of Nat. Hist., August, 1842 ; also in 
 loc. cit. vol. xi. 428. 
 
 Hab. Cheshunt : A. H. H. 
 
 " I have only once met with the above species, and then 
 but in small quantity : it is therefore no less rare than it is 
 curious. Each series of cells is an epitome of the entire plant, 
 which consists but of an aggregation of such series. A 
 sketch of it was forwarded to Dr. Greville, who did not hesi- 
 tate to agree with myself in the opinion of its distinctness." 
 
 4. Draparnaldia condensata ^as^. 
 
 Plate XI. Fig. 1. 
 
 Char. Filaments of considerable size, sparingly branched. 
 Branches /(!«'?t/i'^c(Z xcith short cilia. Cells abbreviated. 
 
 Hassall, in Annals of Nat. Hist. vol. xi. p. 429. 
 
 This is one of the finest and most distinct species of the 
 genus. The only locality at present known for it is a large 
 fish pond opposite Mr. Bosanquet's school for gu'ls in the 
 parish of Wormly, Hertfordshire. It differs from the two 
 preceding species in several respects. It is more sparingly 
 branched, the ramuli are never tufted, and the cilia rarely 
 prolonged: the cells are very short, usually broader than 
 long, and entirely filled with endochrome. The habit of the 
 plant is also dilTerent, dwelling in water less fresh, and its 
 colour in consequence is less vivid than in most other Dra~ 
 parnaldicB. 
 
DRAPARNALDIA. 123 
 
 5. Draparnaldia tenuis Afj. 
 
 Plate XI. Fig. 2. 
 
 Char. Filaments slender, ciliated, sparingly hranched. 
 Brandies usually simple and solitary, hut sometimes sub- 
 fastigiate. Cells of the stems twice or thrice as long as 
 broad, those of the branches rather longer than broad. 
 
 Hob. Streams near Cheshunt : A. H. H. Eeservoir, Ar- 
 drossan : 3faJor Blartin. Between Pembury and Tun- 
 bridge ; Hawkhurst and Gondhurst, Kent : Mr. Jenner. 
 
 This is a much smaller species than any of tlie preceding, 
 is more tenacious, and an inhabitant of streams and rivulets, 
 tlie current of which is strong. Filaments very slender, four 
 to six inches long, irregularly or alternately branched, more 
 or less furnished with scattered or subfasciculate ramull, 
 whose tops are either acute or drawn out into long setaceous 
 colourless points. Joints of the main filaments and ramuli 
 coloured or transversely banded. " At first the filaments are 
 enclosed in the manner of a ChcBtophora in a common some- 
 what definite gelatine ; afterwards, on its bursting, they issue 
 from it like a Conferva, but are at all times very gelatinous." 
 — Harvey, Manual of Brit. Alga, p. 122. 
 
 6. Draparnaldia elongata Hass. 
 Plate X. Fig. 3. 
 
 Char, Filaments very slender, ciliated. Ce\ls fasciated, usually 
 three times as long as broad. 
 Hassall, in Annals of Nat. Hist, for August, 1842 ; also 
 in loc. cit. vol. xi. j). 4. 
 
 Hab. Cheshunt : A. H. IT. Parkind : Major Martin. 
 
 The filaments in this species are finer than those of D. 
 temds, and the cells longer. I have no doubt of its dis- 
 tinctness. It is a rare species, and I have only twice met 
 with it, once growing in a horse trough near Cheshunt. 
 
124 CHJ5TOPnOREyE. 
 
 7. Draparnaldia nana Hass. 
 Plate X. Fig. 3. 
 
 Char. Filaments highly mucous, very slender, sioaringhj 
 branched. Branches acuminate, not usually ciliated. 
 Cells rather broader than long. 
 
 Draparnaldia sparsa Hassall, In Annals of Nat. Hist. xi. 
 428. Conferva nana Dillw. Brit. Conf. t. 30. 
 
 Hab. Cheslmnt and neighbourliood : A. H. H. Steven- 
 ston : Rev. D. Landsborough. 
 
 This is by no means an uncommon species during the spring 
 and early part of the summer, being found attached fre- 
 quently to dead leaves and sticks. In the fineness and mucosity 
 of its filaments, as well as in the shortness of its cells, it seems 
 to exhibit some relation to the genus Clmtophora (a bad name, 
 since the species of the genera Batrachospermum and Drapar- 
 naldia are likcAvise choitophorous). From D. tenuis and D. 
 elongata It is distinguished by the absence of cilia, shorter 
 cells, and from the former again by its smaller size. 
 
 9. CH^TOPHORA Schranh. 
 
 Char. Filaments imbedded in a gelatinous matrix, ivhich is 
 cither globose or lobed, rarely plain and crustaceous ; ag- 
 gregated, branched, articulated, sometimes setaceous, and 
 issuing from a common base. Branches nearly colourless. 
 Eamuli coloured. Capsular fructification has only been 
 noticed in C. pisiformis, C. jjellita, and C. tubercidosa. 
 
 Derivation, From %atT77, a bristle, and (^opzco, to bear. 
 
 ChcEiojjhora Schrank; Lyngb. p. 65, 66. ; Fl. Danica, 1. 1728. ; 
 Agardh, Syst. xix. ; Ore v. Scot. Fl. t. 150. Biv7i- 
 laria Bonnemais, In Jour. Physic, xciv. p. 176. il/y- 
 riodactylon Desv. in Jour. Bot. 1809, p. 307. Anhaltia 
 Schwahl, in Limiffia, ix. p. 127. t. 2. fig. 1.2. Batra- 
 chospermum sp. Vauch. Conf. t. 12. f. 1, 2. t. 13. 
 fiir. 1, 2. 
 
CHTETOPIIORA. 125 
 
 Tlirough Draparnaldia tenuis and D. nana there is an 
 easy and natural transition to this genus. 
 
 Imbedded in the gehitinous matrix, are usually, in the 
 older specimens, a number of stony particles; these have been 
 supposed to be in some way or other connected with repro- 
 duction. Vaucher regards them as the ruptured cells of the 
 plant, and destined to reproduce the species. 
 
 1. CniETornoRA dilatata Hass. 
 Plate XIII. Fig. 2. 
 
 Char, Filaments much branched, fasti[)iatc. Extremities 
 dilated. 
 
 Hah. Ireland : Mr. Moore. 
 
 This species I discovered accidentally, mixed up with a 
 specimen of Nostoc muscorum. It is very remarkable. 
 
 2. ClI^ETOPIIORA ENDIVIiErOLIA Ag. 
 
 Plate IX. Figs. 1, 2. 
 
 Char. Mucous matrix somewhat compressed, sub-dichoto- 
 moushj branched. Primary \ix:sxi(^\Q,^ frequently par cdlel ; 
 apices of ultimate ramuli ciliated. 
 
 Batrachospcrmum fasciculatum Vaucher, Hist, des Conf. 
 d'Eau douce, p. 116. pi. xiii. fig. 1.; Harvey in Hooker's 
 Brit. Flor. ii. p. 389. Ulva incrassata, E. Bot. 967. 
 Clmtophora endivicefolia Harv. in INIanual, p. 122. 
 
 Hob. Common in streams. 
 
 " This Batrachosjjerinum is more rare than the preceding 
 species B. moniliforme, B. plumosum, and B. glomeratum : it 
 is met with in slowly running w^aters, covering stones, to which 
 it is attached, under the form of a little green protuberance 
 irregularly lobed at its extremities. It is but little more 
 than a few lines in length, and about half as broad. It can 
 scarcely be distinguished with the unaided sight, but Avith 
 the microscope it appears curiously composed. If but a very 
 
126 cn^TorHORE^. 
 
 small fragment be examined, it will be seen, witli surprise, 
 that it is formed of an assemblage of principal filaments, 
 parallel, elongated, and which bear at their extremities sub- 
 divisions, very short, composed of three or four branches. The 
 white grains are here seen in great quantity, which proceed 
 from ruptured rings, and are destined to reproduce the plant, 
 so that it is difficult to doubt the destination of these grains, 
 even when this has not been confirmed by direct proofs. 
 
 " This Batrachosperm, without doubt, has not yet been 
 described, and it is necessary to observe, that it is difl5cult 
 to discern at first sight a Conferva in the gelatinous material 
 which forms it, but that which is obscure to the simple sight 
 becopes distinct to the microscope.'' — Vaucher. 
 
 IMr. Harvey, in his description of this species, compares the 
 mode of branching of the frond to stags' horns, a comparison 
 which conveys a very good idea of the appearance of this 
 beautiful object. 
 
 3. CHiETOPHORA TUBERCULOSA Hook. 
 
 Plate IX. Figs. 7, 8. 
 
 Char. " Gelatinous matrix, at first glabrous and firm, after- 
 wards vuicli lobed, fragile, and hollow. Filaments vcrg 
 slender, fiexuous, hyaline. Hamuli coloured, palmate, fas- 
 ciculate.^' — Harvey. 
 Harvey, in Hooker's Brit. Flor. Bivularia tuberculosa, E. 
 Bot. t. 2366. Ch. tuberculosa Harve}^ In JNIanual, p. 122. 
 Hab. Diana Pond, Bushey Park ; A. H. H. Aberdeen : 
 Dr. Dickie. Neighbourhood of Manchester : Mr. Side- 
 hotham. Barnett's Wood, near Tuubridge Wells : Mr. 
 Jenner. 
 
 " On sticks and aquatic plants In boggy pools. Fronds 
 bright green, an inch or more in diameter." — Ilarv. 
 
 It Is doubtful as to whether this is to be regarded as 
 any thing more than a variety of the following species, C. 
 elegans, the Batrachospermum intricatum of Vaucher, or that 
 species much developed ; the softness and hollowness of the 
 matrix both resulting from the extraordinary developement. 
 
cniETornoiJA. 127 
 
 In Englisli Botany the filaments arc figured without cilia. 
 Kiitzing also figures them in the same manner : if this 
 character be permanent, then is the species doubtless a 
 good one. 
 
 The fi3llowing observations, taken from the " Flora " for 
 1842, p. 513., were inserted in the "Annals" for June, 
 1843: — 
 
 " The fruit of Chmtopliora appears hitherto to have been observed 
 only by Mr. Berkeley, who communicated specimens to Captain Car- 
 michael, vrho made a drawing from them ; which, with his other manu- 
 scripts, is in the hands of Sir W. J. Hooker. Mr. Berkeley also pub- 
 lished a figure of it in his " Gleanings of British Algfc." Dr. Muller of 
 Detmold has been so fortunate as to meet with similar fruit in Ch(c- 
 tophora tuberculosa, and has given figures of it in the place cited above. 
 He has made, moreover, a very curious observation, viz. that the fruit is 
 accomijanied by, and at length connate with, a red globule of a similar form 
 but smaller size, which he considers as the male fructification. As the 
 female capsule advances to maturity, the male approaches it, becomes 
 elongated, and at length is united with it, emptying the pollen globules 
 into the female fruit. This process being accomplished, it falls off. 
 
 " Whatever may be thought of this, his account of the developement 
 of the spores formed within the capsule, which are about five in number, 
 and disposed around an aperture occasioned probably by the pressure of 
 the male capsule, is not less wonderful. From each of the seeds a hyaline 
 thread is developed, formed of the globules which press forward from the 
 inside of the seed ; this at length becomes green, and consists of a very 
 tender hyaline tube filled with a monlliform row of globules. Finally, 
 the upi^ermost globule is elongated into a new tube, which is of a paler 
 green than the rest of the thread. The capsule is now no longer visible, 
 and the whole resembles a Rivula?-ia, which soon assumes the form of 
 ChcetopTiora tuberculosa. 
 
 " The above observations are at least curious, and, if there has been no 
 error, are of much importance. We recommend them to the consider- 
 ation of some of our practical algologists, hoping that they may be able 
 to throw some light upon the matter." 
 
 4. CniETOPHORA ELEGANS A^. 
 
 Plate IX. Figs. 3, 4. 
 
 Char. Mucous matrix subglohosc, or lohed, rather soh'cf, 
 
 green. Filaments suhdichotomous. ^^\\\\\\\ fasticjiate, the 
 
 apices produced beyond the gelatine and setigerous. 
 
 Batrachospernmm intricatum Vaiich. Hist, des Conf. d'Eaii 
 
 douce, p. 117. pi. xli. figs. 2, 3. C. elegans Harvey, 
 
128 CH.ETOPHORE.E. 
 
 in Hook. Brit. Flor. p. 389. ; also iu Manual, p. 122. 
 C. elegans Ag. 
 
 Hah. On sticks, &c., in stagnant pools, common. 
 
 " No species is more easy to recognise ; it is formed of 
 gelatinous protuberances of all sorts of figures, and of a 
 diameter which varies from a point to an inch." — Vaucher. 
 
 5. Ch^TOPHORA PISIFORMIS Ag. 
 
 Plate IX. Figs. 5, 6. 
 
 Char. Frond suhglobose, fieslxy, green. Filaments suh- 
 dichotomous, obtuse. Sporidia globose, axillary. — Carm. 
 
 Harvey, in Hooker's Brit. Flor. p. 389. ; Berk. Alga;, 1. 1. 
 fig. 1. ; Grev. Crypt, t. 150. 
 
 Hob. In subalpine lakes. 
 
 Mr. Berkeley has discovered capsular fructification on this 
 species, and Kiitzing has figured similar capsules as belonging 
 to C. tuberculosa. The occurrence of these capsules must be 
 regarded as excessively rare, and therefore commonly con- 
 sidered as the only mode of reproduction possessed by species 
 which are everywhere so abundant. 
 
 6. CHiETOPHORA LONG^VA Car7n. 
 
 Char. '* Frond indejinitelg effused, incrusting, gelatinous, 
 green. Filaments subdichotomous. Hamuli produced 'pro- 
 liferous towards the apex.'''' — Carm. 
 
 C. longava Harvey, in Hooker's Brit. Flor. ; also in 
 Manual, p. 123. 
 
 Hab. In a boggy stream at Appin : Captain Carmichael. 
 
 " Fronds, continuous, or so closely set as to have that ap- 
 pearance, of a delicate green colour, and more flaccid than 
 those of C. elegans, apparently from a deficiency of gelatine. 
 Filaments in all respects similar to those of other species, 
 excepting in being mostly proliferous." 
 
 I cannot regard this as a distinct species, and would refer 
 to it C. cndivicefolia or C. tuberculosa. 
 
129 
 
 Fam. YIII. CONJUGATEiE. 
 
 Char. Filaments simple, equal, often conjugating. En- 
 dochrome mostly figured. ^^orsiVigia, formed generally by 
 the union of the contents of two cells, either iji different or 
 in the same filaments. 
 
 The ConfervcE, -which we now propose to examine, are pci'- 
 haps the most curious of all their tribe. When viewed to- 
 gether, they form an exceedingly natural group, but one which 
 is defined rather by the enumeration of a number of cha- 
 racters than by one in j^articular. 
 
 Their filaments when examined with the microscope are 
 seen to be sim23le and of uniform diameter; they are for the 
 most part unattached, and in their young condition are 
 smooth and unctuous to the touch, and of a deep green colour : 
 they are formed of an assemblage of elongated cells placed 
 end to end, and all of them enclosed and held in union by 
 an investing membrane, common to all, the interior of these 
 cells being occupied, chiefly with endochrome, which is 
 variously disposed, sometimes in the form of spires and stars, 
 at others it comi^letely fills their cavities : mixed up with this 
 endochrome, are observed numerous vesicles ; these being it is 
 jDresumcd the unfertilized zoosi3ores. 
 
 '\Anien the filaments have attained a certain age or period 
 of developement, most of the cells are seen to send forth a 
 little conical process, which unites with a similar protrusion 
 from a corresponding cell of a contiguous filament, an un- 
 interrupted passage of communication between the two cells 
 being thus established. 
 
 While this is occurring, the s^jiral tubes, if the species be 
 a Zygncma, become confused and coalesce in each cell, the con- 
 tents of one passing out through the passage of connnunication, 
 mingling with those of the other, and both uniting, are at 
 length moulded into a dark body of either an oval or circular 
 form, and enveloped in membranes ; and which Vaucher, 
 
 K 
 
130 CONJUGATED. 
 
 M. Decaisne, and Mr. Jenner regard as the true spores, but 
 which, Agardh declares, resolve themselves after a time into 
 zoospores, an opinion in which I concur, applying the term 
 sporangia to them. 
 
 The tubes of communication do not appear to issue from 
 any determinate point of each cell, but from that which lies 
 in nearest contact with a neighbouring filament ; the filaments 
 appearing to exercise a mutual attraction on each other : thus 
 a number will be given off in succession to corresponding 
 ones of a filament near to it on one side, while another set from 
 the same filament will unite w^ith those of another coming 
 near to it in some other part of its length. 
 
 It is curious to remark that the cells in one part of the 
 same filament will part with their contents and remain 
 empty, ^vhile in another, they will be the recipients of the 
 contents of the cells of another filament. 
 
 This remarkable mode of union of the filaments, almost 
 without parallel in the vegetable kingdom, was first noticed 
 by Miiller in a species which he named Conferva jugalis. 
 Miiller, however, did not entertain the slightest suspicion that 
 it was in any way connected with reproduction. 
 
 Since the time of the publication of Vaucher's " Histoire 
 des Conferves d'Eau douce," in 1803, but little seems to have 
 been added to the information contained in that excellent 
 work in reference to this division of the Alg(£, in which the 
 phejiomenon of union of the cells is shewn to belong to very 
 many species, which Yaucher for the most part has satisfac- 
 torily determined, notwithstanding the feeble power of the 
 instrument employed by him in their investigation. The 
 labours, however, which I have bestowed upon the fresh- 
 water AlgcB have been rewarded with a few discoveries of 
 interest, one of which I shall now proceed to notice. 
 
 This relates to the fact, that certain species of Conjugated, 
 belonging principally to the genus Zygnema, occur, in which 
 there is no union of the different filaments similar to that al- 
 ready described ; the spoi-angia being formed in these by the 
 concentration of the matter of two cells in the same, and not 
 as in the preceding casern different, filaments. This interest- 
 ing fact was first announced by me in a paper on the Zygne- 
 
CONJUGATEiE, 131 
 
 mata inserted in tlie 9th vol. of tlie " Annals and Magazine of 
 Natural History," p. 34. Since this paper was published I have 
 observed, in Dillwyn's " Synopsis of the British Freshwater 
 Alga;," that a non-conjugating Zijgnema has been described 
 accurately by INIr. Woods, under the idea of its being a variety 
 of Zygnema quininum. The accuracy of the description would 
 appear, however, to have been doubted, since we find no refer- 
 ence to the species, which is distinct, and not a variety of that 
 to which it was referred, made by subsequent writers on the 
 AlgcR. Mr. Harvey in his excellent " Manual " does not make 
 any mention of it. 
 
 In these non-conjugating Zygnemata the tubes of commu- 
 nication issue from the opposed extremities of the cells, and 
 not from the centre of the sides of the cells, as in the conju- 
 gating Zygnemata. 
 
 The analogy which exists between the conjunction of the 
 filaments of the ConjvgatecB and the reproduction of animals 
 has led to the opinion being entertained by some that they 
 are animal and not vegetable productions. The erroneous 
 nature, however, of this view is easily proved by reference to 
 the non-conjugating species mentioned, these testifying that 
 the conjunction of the filaments is not an occurrence essential 
 to the perpetuity of the species, and that therefore no argu- 
 ments in favour of the animality of the ConjugatecR ought to 
 be founded on that circumstance. The union, however, 
 of distinct cells in the same filament might be regarded 
 as indicative of an animal nature ; but this view may be dis- 
 proved by reference to another genus of freshwater Algce, of 
 the vegetability of which there can be no question, viz. Vesi- 
 culifera, in which there is an union of the matter of two cells 
 in the same filament, though no tubular connection between 
 those cells. Now the analogy between the species of this 
 genus and the non-conjugating Zygnemata is too great to 
 permit of the oi^inion being entertained, that the former are 
 vegetables and the latter animals. 
 
 Some have accounted for the union of the filaments by 
 supposing that the entire of one filament contained fertilizing 
 and the other fertilizable material ; but this view is like- 
 wise shown to be erroneous by the occurrence of uon-con- 
 
 K 2 
 
132 CONJUGATEiE. 
 
 jugatmg species. If two kinds of reproductive matter exist, 
 as most suppose, they must both be contained in the same fila- 
 ment in these species ; but even this view cannot be received 
 when it is known that certain species of the family Conjugates 
 occur in which there is not even a union of the matter of two 
 cells, but in which the sporangia are formed separately within 
 each ; as in Mesocarpus notabilis and Zygnema mirahile. 
 
 It would thus appear that no argument can be deduced 
 from the conjunction of the cells in the same or diiferent fila- 
 ments and the commingling of their contents in favour either 
 of the animahty or sexuality of the Conjugatece^ and that the 
 phenomenon, remarkable as it is, is subservient to some se- 
 condary purpose in the economy of these productions. 
 
 The species of this group of Confervce may be found occa- 
 sionally in a state of conjugation during the entire of the 
 spring, summer, and autumnal months ; they are chiefly met 
 "with, however, in this state in the spring. It is usually some 
 days after this union of the cells has been established, that the 
 slow emanation of the matter of one cell occurs, this trans- 
 ference being occasioned apparently by the mutual attraction 
 exercised by the contents of each cell on that of the one to 
 which it is joined ; this attraction, in correspondence with the 
 law of gravitation, being predominant in that cell which con- 
 tains the greatest bulk of matter ; and thus, I think, we may 
 account for the contents of a number of cells of one filament 
 passing to those of another set of cells of another filament, 
 the matter in them being more considerable in quantity. 
 
 Very soon after the contents of the cells have united, they 
 are seen to dispose themselves into a regular form, and in the 
 course of three or four days the sporangia are perfected, each 
 being invested with its two or three membranes. 
 
 For some time, not unfrequently extending to weeks after 
 the cells have conjoined, and the sporangia have become or- 
 ganized, the species does not appear to undergo any further 
 change : at length, however, the tubes of communication 
 separate, the cells become disjointed, indicating the death of 
 the plant, respii'ation ceases, and the disunited fragments fall 
 to the bottom of the water, the sporangia being set free on the 
 entii-e disorganization of the plant or the zoospores bursting 
 
CONJUGATED. 133 
 
 through the membrane which invests them, escape through 
 the open extremity of the communicating tubes. 
 
 When in a young condition, and before reproduction takes 
 place, the ConjugatecB are of a bright, beautiful, and shining 
 green colour, are highly lubricous to the touch, and the in- 
 dividual filaments are never entangled together, but placed 
 somewhat jjarallcl. As soon, however, as a union of the 
 filaments has occurred, these characters are for the most part 
 lost. The rich green colour fades to a yellow tint ; the fila- 
 ments no longer ghsten when removed from the water, or 
 feel slippery, but almost harsh and crisp under the fingers ; 
 they are now likewise much curled and twisted. The change 
 of colour is the result of diminished vitality, and the loss of 
 lubricity arises from the extension, amounting almost to ob- 
 literation of the sheath. 
 
 The Conjugateco, Avith a single exception, dwell in Avaters 
 that are perfectly still, such as ponds, reservoirs, ditches, 
 pools, and extended marshes ; they are also, with a single 
 exception, unattached, roots not being necessary to them, for, 
 imlike the greater part of the Algm which have hitherto been 
 considered, and which are all provided with rootlilce organs, 
 they incur no risk of being swept away by the force of the 
 river, stream, or cascade in Avhich they delight to dwell. 
 The union between the filaments which is to occur, renders 
 a locality of the above description an essential to the very 
 existence of this family of plants, for without absolute 
 quietude of the water this conjugation would be frustrated. 
 In the only attached species Avith which I am acquainted, 
 and Avhich dwells in floAving water, I have never detected 
 conjugation of the threads. 
 
 The ConjugatecB adhere strongly to paper, preserving their 
 shining appearance, but never their brilliant colours ; these 
 generally becoming almost black in drying. 
 
 The quantity of air or gas eliminated by the Conferva^ 
 but principally by the Conjygatecp., in Avarm sunny Avcathcr 
 is very considerable. It is by means of the globules of air 
 given out by these plants in respiration, that such large 
 masses as are seen in the spring and summer montlis, covering 
 almost every pond and ditch, are sustained upon the surface, 
 K 3 
 
134 CONJUGATED. 
 
 the globules becoming entangled amongst their filaments 
 render them specifically lighter than the water, and cause 
 them to crepitate under the finger when pressed upon. The 
 presence of these globules in warm weather causes the Con- 
 jugatecB and other Conferva to present a vesicated or bullous 
 appearance, which the older algologists thought to be cha- 
 racteristic of a single species, which they named Conferva 
 hullosa : this appearance is now known to belong to a whole 
 host of Aiya generically distinct — such is the progress of 
 scientific research and knowledge. Dillwyn, in his descrip- 
 tion of Conferva fr acta, observes, that, "after being dried, 
 the Conferva bullosce have been used as wadding for stuffing 
 garments, and made mto coarse household linen." Weiss, in 
 his " Plantse Cryptogamiaj Flor^ Gottingenses," p. 23, relates, 
 that formerly the river Unstrut, after inundating a large tract 
 of country in Upper Saxony, on again retiring into its proper 
 channel, left a great quantity of Conf. bullosa, which having 
 been gathered and dried by the inhabitants, was used by them 
 for stuffing their garments ; but that it occasioned violent pains 
 in their limbs : it was also used for making coarse paper." On 
 some parts of the Continent serious injury bas been done 
 to large tracts of country, by the deposit, on the subsidence 
 of the waters which have covered them for a period, of a 
 compact layer of these ConfervcB bulloscB, which has pre- 
 vented the growth of the grass beneath, and thus deprived 
 the cattle of their food. So great an evil has this been 
 deemed of late years, that commissioners have been appointed 
 to investigate the nature of this deposit, and to endeavour to 
 devise some means to remove and prevent its re-formation. 
 
 M. Decaisne, in his " Memoir on the Classification of the 
 Algoe," has, on grounds wliich, on mature consideration, I 
 cannot regard as satisfactory, separated this group from 
 Agardh's class of zoospores, in which I would retain it ; for 
 certain it is that one division of the group of sunsjiores of 
 M. Decaisne, viz. the true Confervece, are propagated by 
 means of zoospores. 
 
 The numerous species of this group resolve themselves 
 naturally into the genera Zygnema, Tyndaridea, Staurocarpus, 
 Mesocarpus, and Mougeotia. 
 
ZYGNEMA. 135 
 
 10. ZYGNEMA Ag. 
 
 Char. Endocliromc arranged in spiral order toithin each cell. 
 Sporangia generally oval, and never lodged in the trans- 
 verse tubes of communication. 
 
 Derivation. From ^vyog, a yoke, and v>]]x«, a thread. 
 
 Spirogyra Link, Handb. ill. 261., Mcyen, In Llnua^a, il. 
 410. Choaspis Gray. Salinacis Bory, in Diet. Class. 
 XV. p. 75. c. Iv. t. 45. Conjugat(B sjj. Vauch, Conf. d'Eau 
 douce. 
 
 The first of these genera Is characterized by the endo- 
 chrome with its brilliant granules (which Miiller, in his sur- 
 prise on first discovering a species of the genus, likened to 
 j^reclous stones), being arranged in a sjjiral form, the number 
 of spires being from one to eight. 
 
 The species of this genus admit readily of division into two 
 subgenera, in the one of wdiich the filaments iiuite, and in 
 the other no conjugation takes place ; and each of these di- 
 visions allows of further analysis, founded on the conforma- 
 tion of the cells. 
 
 " In the first of these subdivisions, Avhich for the most 
 part includes the long-celled species of the genus, such as 
 Zygiicma elongatum and Z. quadratuniy &c., the 02)posed ex- 
 tremities of all those cells lohich have attained maturity are 
 considerably inverted, and Avhich inversion may be compared 
 to that of the finger of a glove (PI. xvii. fig. 4.) ; while in the 
 second, which embraces the short-celled examples, as Zyg- 
 nema maximum, Z. nitidum, and very many others, the cells 
 are not inverted, but touch each other by their plane surfaces. 
 
 " The form of this inversion is, in all the species In which 
 it occurs, identical and extremely regular, its circumference 
 being circular, and its base somewhat flat ; no membrane In- 
 tervenes between the spaces formed by this indoubling in 
 contiguous cells, which spaces therefore connnunicate directly 
 with each other. 
 
 " At the period of reproduction, and at no other, one of 
 the two indented and opposed extremities of certain cells be- 
 
136 CONJUGATED. 
 
 comes everted and protruded into tlie cavity of the other. 
 (PI. XYII. fig. 5.) 
 
 " The cause of this protrusion, and the reason why it only 
 occurs at the precise period of the reproduction of the cells, 
 are easily accounted for, and both arise from imequal internal 
 pressure of the contiguous cells on each other, which ine- 
 quality of pressure is produced by the emission of the endo- 
 chrome of one cell into a neighbouring cell either in the same 
 or different filaments ; thus, when a cell has discharged its 
 contents, its cavity is empty, and no resistance can be offered 
 by it to the protrusion of the inverted portion of the adjacent 
 cell or cells, replete as it or they may be with fluid and en- 
 dochrome. This explanation applies likewise to the fact, that 
 when a number of cells have either emptied themselves of 
 their contents, or have been the recipients of those of other 
 cells at the same time, no eversion takes place, for in this case 
 there is no inequality of internal pressure. 
 
 " But while a correct exposition may be given of the cause 
 of this protrusion and intromission, it is not so easy to oflTer 
 a satisfactory explanation of the purpose to be attained by it. 
 The eversion, doubtless, assists in effecting the dislocation of 
 the cells, and thus, reproduction being perfected, hastening the 
 destruction of the species and dispersion of the spores ; pro- 
 cesses, w^hlch, from the greater length of the cells and con- 
 sequent continuity of the enveloping sheath, would possibly 
 occupy, were it not for some special provision of the nature 
 indicated, a much longer time than in the short -celled species. 
 A subordinate and not unimportant use of this provision is, the 
 assistance whicli it aflfords in the determination of alHed species. 
 
 « It is remarkable that no similar conformation presents 
 itself to our notice in the genera Tyndaridea and Mougeotia, 
 so closely allied to Zygnema, for in these the cells invariably 
 terminate by plane surfaces, which, however, may be either 
 everted or inverted to a slight extent. 
 
 " This peculiar formation of the cells of some Zygnemata 
 w^as first noticed by me in the spring of 1842, but its true 
 uatiu-e only became apparent to me in the early portion of 
 the present year. When A^ewed tln-ough a low power of the 
 microscope, and in a Zygnema whose filaments are as yet 
 
ZYGNEMA. 137 
 
 separate, it exhibits the appearance of two curved knife- 
 blades slightly ajiproximating to each other at their apices, 
 near to which usually lies the divided spiral thread, and 
 strongly impressing the superficial observer, from the position 
 and asjjcct of these blades, with the idea that they are the 
 instruments which effect its separation, and reminding him of 
 the beautiful provision whereby the section of pollen granules 
 is accomplished. 
 
 " On transmitting a short time since a specimen of the 
 Zygncma quadratum, in a state of reproduction, to the Rev. 
 M. J. Berkeley and ISIr. Ralfs, but unaccompanied by any 
 remarks in reference to the structure of the cells, both these 
 gentlemen noticed their peculiar conformation, and from the 
 former I received correct sketches of their appearances. 
 
 '^ The structure of the joints in Zygnema was long since 
 noticed in one species of the genus by Mold, who thus de- 
 scribes it in his paper upon the multiplication of cells by 
 division, inserted in the ' Flora ' : — ^ In Z. elongatum Ag., 
 the dissepiments have a very peculiar structure, which I have 
 found in no other species. The terminal surface of each cell 
 is not even, but elongated into a blunt conical process. This 
 process can only be observed in its true state when two joints 
 are separated one from the other ; when, on the contraiy, the 
 threads are unbroken the j^rocess is generally introverted like 
 the finger of a glove, and exhibits the form represented at 
 PL I. fig. 8. a, by c. Tills is the common condition, and ia 
 most threads no joint is found otherwise constructed. But I 
 have now met with a single thread in which a part of the 
 articulations has the ordinary length, while another part has 
 joints only half as long. In these shorter articulations it 
 Avas normal that only the alternate dissepiments had the 
 structure i^ecullar to this species (so that by these dissepi- 
 ments the thread was divided into articulations of the ordinary 
 length), Avhile, on tlie contrary, the intermediate dissepiments 
 exhibited the form usual in ConfervcB.''^ 
 
 " The observation, that ' this process can only be observed 
 in Its true state (that is, everted) when two joints are sepa- 
 rated, the one from the other,' is inaccurate, for the cells may 
 be separated and yet the processes inverted, the cvcrslon of 
 
138 CONJUGATE^;. 
 
 tKem having nothing whatever to do with the separation of 
 the cells, and never being in any case the result of it, but 
 depending, as explained already, upon unequal internal pres- 
 sure, and occurring chiefly at the period of reproduction. 
 The effect of the eversion is, as already observed, to occasion 
 the dislocation of the cells. 
 
 : " Again, in every filament of those Zygncmata which ex- 
 hibit the inverted structure, cells may be observed terminating 
 in the ordinary manner of Confervoe, viz. by plane surfaces, 
 the presence or absence of the inversion depending upon the 
 period of the formation of the disse2:>iments ; the older ones, 
 or, as observed in the beginning of tliis notice, the more 
 mature ones only presenting it. Thus it follows that the 
 opposed extremities of cells always exhibit the same structure, 
 and that this alternation in form supplies evidence the most 
 conclusive of the multiplication of cells throughout the eyitire 
 Jilament of a Conferva by division." * 
 
 , It is in this genus that the radiated organ described in the 
 Introduction is best developed, and may be observed with 
 most advantage ; it is here also that the cruciform organs, 
 sup^Dosed to secrete the raphides, and the curved strings of 
 cytoblasts, before noticed, are most clearly seen. 
 
 Attention to the structure of the cells in the Zygnemata is 
 of the very first importance in the discnmination of species, 
 it being the only distinguishing character in some closely 
 allied species. 
 
 First Subgenus. — Filaments conjugating. 
 * Extremities of the cells truncated. 
 
 a. Spires numerous. 
 
 1. Zygnema orbiculaee Hass. 
 
 Plate XIX. Figs. 1, 2. 
 
 Char. Filaments highly mucous, and of a light green colour, 
 
 * From a paper entitled " Observations on some Points in the Ana- 
 tomy and Physiology of the Freshwater Algse," by Arthur II. Hassall, 
 inserted in the "Annals and Mag. of Natural History," vol.xii. pp. 26 — 8. 
 
ZYGNEMA. 139 
 
 their diameter and length being very considerable. Cells, 
 when in a state of conjugation, a little longer than broad, 
 prior to which, however, they are frequently not half so 
 long as broad ; winding round the interior of these are 
 about eight spiral threads, the granules in them being small. 
 Sporangia almost circular, flattened. 
 
 Z. maximum Hassall, in Annals of Nat. Hist. vol. x. p. 36. 
 
 Hab. Cheshunt, Hertfordsliire, and the country adjacent ; 
 Notting Hill : A. II H. Waldron and Wortliing ; Mr. 
 Jenner. Graham Castle : Major Martin. 
 
 This Is one of the finest as well as largest of all the Zygne- 
 mata hitherto described, the diameter of the filaments greatly- 
 exceeding those of Z. nitidum, tlie Conjugata -princeps of 
 Vauclier. It is found only in ponds and dykes whose waters 
 are deep and permanent, and it does not conjugate until near 
 the end of the summer. The only other Zygnema with which 
 it could possibly be confounded is Z. scrratum, between which 
 and the present plant several well marked differences exist, 
 as will presently be shown. Two varieties of this plant were 
 described by me In the 11th vol. of " Annals and INIagazIne 
 of Natural History," p. 432. both of which I now feel as- 
 sured are quite distinct. The first of these is Z. alternatum. 
 
 2. Zygnema alteenatum Hass. 
 Plate XX. 
 
 Char. Filaments of the same diameter as those of the preceding 
 species. Cells rather longer than broad. Spires 7iumerous, 
 granules small, conjugation alternate, that is, every second 
 pair of cells alone conjoin. 
 Hassall, Annals of Nat. Hist. vol. xi. p. 432. Zygnema 
 Decaisne, In INIcraoire sur la Classification dcs Algues, 
 An. des Sclen. Nat. 
 Hab. Cheshunt, Hertfordshire. A. II. H. 
 This is one of the rarest species of the genus, and I am not 
 sure that I liave ever met with it more than once. Tlie mode 
 of conjugation of the cells, tlie alternate ones only uniting, ia 
 
140 CONJUGATED. 
 
 curious, and is confined to this and the following species. 
 The design of the interrupted conjugation is by no means 
 evident : it is remarkable, however, that the granules in those 
 cells, which remain disunited, decrease in size and become 
 almost colourless, while those of the conjoined cells increase 
 considerably, and darken in colour. This mode of conjugation 
 at least affords a decisive character by which it and the 
 following species may be known from all others hitherto de- 
 scribed. One fact is still wanting to complete the history of 
 tliis species, viz. the form of the sporangia, which might 
 possibly furnish an additional distinctive character. 
 
 3. Zygnema intereuptum Hass. 
 
 Plate XXL. 
 
 Char. Filaments of considerable length, hut less in diameter 
 than those of Z. orhiculare. Cells at the j)eriod of conju- 
 gation rather longer than broad : previous to this, hoivever, 
 they are frequently not half so long as broad. Spires nu- 
 merous. Conjugation interrupted. Spire oval, equalling in 
 breadth the diameter of the cell but not producing any 
 inflation of it. 
 
 Hassall, in Annals of Nat. Hist, vol, xi. p. 432. 
 
 Hab. Cheshunt: A. H. H. 
 
 This also is a very rare species. I have only met with it 
 once, but then in very considerable quantity. It bears a 
 close resemblance to Z. alternatum, but differs from it in 
 having filaments which are considerably smaller than those in 
 that species. The granules or unfertilized zoospores are like- 
 wise largest in those cells which have conjoined. 
 
 4. Ztgnema serratum 7/as5. 
 
 Plate XXIII. Figs. 1,2. 
 
 Char. Filaments of nearly the same diameter as those of 
 Z. orhiculare, hut less mucous. Cells longer than broad. 
 Spires varying from three to five in number. Granules 
 larger. Conjugation continuous. Sporangia broadly 
 ovate. 
 
ZYGNEMA. 141 
 
 Hassall, In Annals of Nat. Hist. vol. xi. ]). 432. 
 Hab. Cliesliunt, very rare : A. II. JL Withy liam : Mr. 
 Jenner. 
 
 The only species with which this can possibly be confounded 
 is Z. orhiculare, from which it may be readily distinguished by 
 the fewer number and serrated ajopearance of the spires, the 
 larger size of the granules, and the form of the sporangia, 
 which in Z. orhiculare are nearly spherical, and compressed, 
 while in Z. serratum they are broadly ovate. The filaments 
 do indeed resemble very closely in character those of Z. niti- 
 dum, with which, however, there is but little danger of con- 
 founding it, that species being altogether a much smaller plant. 
 It is very rare. 
 
 5. Zygnema nitidum Ag. 
 Plate XXII. Figs. 1, 2. 
 
 Cliar. Filaments of ?H?<c/t less diameter than those of Z. serra- 
 tum. Cells usually rather more than tioice as long as broad. 
 Spires generally four in number. Granules large. Spo- 
 rangia acutely ovate. 
 
 Conferva Jugalis Miiller, Flora Dauica. Conjugata princeps 
 Vaucher, Hist, des Conf. d'Eau douce, p. 64. pi. iv. fig. 1 . 
 F. nitidum Harv. in Manual, p. 143. ; Agardh's Systema. 
 Conf. nitidum Dillwyn, British Conferva?, pi. iv. f. c. ; 
 Eng. Bot. t. 1656, in part. 
 
 Hah. Every where common throughout Great Britain 
 and Ireland. 
 
 This species is one of the best marked as well as most 
 beautiful of the tribe. Numerous other Zygnemata have 
 however doubtless been associated with it under the same 
 name. 
 
 Vaucher has the following observation upon it : — " Inde- 
 pendently of its size, it is distinguished from all others by a 
 coarser touch, a more shining appearance of tubes almost ci'isp, 
 and by its constant habit of raising its extremities out of 
 the water whenever it is immersed in the liquid." 
 
142 C0XJUGATEJ3. 
 
 6. Zygnema belle Hass. 
 
 Char. Filaments about a foot in length, with truncate extre- 
 mities ; of considerable though rather less diameter than those 
 of Z. nitidum, mucous, glossy, and of a deep andbeautiful 
 green colour ; investing membrane of the cells very evident, 
 and transparent. Cells in the young filaments scarcely so 
 long as broad, but their length exceeds their breadth in 
 those which have conjugated ; round the interior of the cells 
 five or six loose spiral tubes may be faintly discerned; 
 these contain the reproductive globules which are large, and 
 distinct, icith a dark central nucleus. Sporangia oval some- 
 times almost circular, and flattened, lying in inflated cells, 
 the cavity of ivhich they do not fill. 
 
 Hassall, iu Annals of Nat. Hist. vol. x. p. 37. 
 
 Hab. Essex, Hertfordshire, and in several places in Mid- 
 dlesex ; abundant : A. H. H. In the pond between 
 Ramslye Rocks and Broadwater Forest, and on Henfield 
 Common : Mr. Jenner. 
 
 This well-marked species is readily distinguished from all 
 others by the size of its filaments, the sporangia almost cir- 
 cular, and the inflated form of the cells. There is not a more 
 distinct or attractive species in the genus. 
 
 7. Zygnema neglectum Hass. 
 Plate XXIII. Figs. 1, 2. 
 
 Char. Filaments of less diameter than those of Z. 7iitidum. 
 Cells rather longer than broad. Spires distinct, serrated. 
 Granules large. Sporangia oval, iyi some specimens, occa- 
 sioning a slight inflation of the cells in lohich they are 
 lodged. 
 Hassall, in Annals of Nat. Hist. vol. x. p. 37. 
 
 Hab. Neighbourhood of Cheshunt and other places ; com- 
 mon : A.HH. Vicinity of Tunbridge Wells and in 
 Kent : Mr. Jenner. 
 
 This species. has doubtless usually been confounded with 
 
ZYGNEMA. 143 
 
 Z. nitidum, of wliicli the filaments are larger ; the spires 
 too, are generally but three in number, and the sporangia are 
 less acutely oval, frequently also i^roducing an inflation of the 
 cells in which they are lodged. 
 
 8. Zygnema curyatum Acf. 
 Plate XXVI. Figs. 1, 2. 
 
 Char. Filaments nearly equal in diameter to those of Z. necjlec- 
 tum. Conjugation amjular. Cells three or four times as 
 long as broad, coalescing without the interventiort of trans- 
 verse tubes. Spires about four in number, faintly indicated. 
 Sporangia oval. 
 Z. curvatum Ag. Conf. stritica, Eng. Bot. t. 24G3. Harvey, 
 Hook. Br. Fl. p. 362., also in Manual. Mougcotia stritica 
 Kiitz. Alg. Dw. Sirogonium striticum Kiitz. Phyc. Gene- 
 ralis, p. 278. 
 
 Ilab. Ditches in Henfield Level, Sussex, and pools on 
 Chy-an Hal ]\Ioor, near Penzance : Mr.Borrer. Ches- 
 hunt : A. H. H. 
 
 This species is remarkable for the direct conjugation of the 
 cells, they uniting with each other without the intervention 
 of tubes of communication, and it is the only species of the 
 genus which does so. By this junction of the cells with each 
 other, the filaments are bent at angles. The direct union of 
 the cells and angular flection of the filaments of this species 
 have induced Kiitzing to form a new genus for its reception 
 under the name of Sirogonium. Z. curvatum seems in some 
 measure to unite the genera Zygnema and Mougcotia, that it 
 is nothing more than a Zygnema, however, is proved by the 
 endochromc being disposed in a spiral order. 
 
 9. Zygnema pellucidum Ilass. 
 
 Plate XXV. Figs. 1, 2. 
 
 Char. Filaments of rather less diameter than those of Z. cur- 
 vatum, mucous, almost franspaj'cnf. Conjugation pai^allel. 
 Cells six or seven times as long as broad. Spires indistinct, 
 
144 CONJUGATED. 
 
 usually four in number . Sj)orangia circular, lodged in cellsy 
 which are considerably enlarged for their accommodation. 
 
 Z. pellucidum Hassall, iu Ann. Nat. Hist. vol. x. p. 37. 
 
 Hab. Chesliunt: A. H. H. 
 
 Tills is a very curious and beautiful sj^ecies, and one by- 
 no means common. I have only once been so fortunate as to 
 meet with it in a state of reproduction, in Avhicli condition it is 
 not possible to confound it with any other described species. 
 
 10. Zygnema rivulaee Hass. 
 Plate XXVII. Figs. 1, 2. 
 
 Char. Filaments seven or eight inches in lengtli, usually at- 
 tached, and in diameter about equal to those of Z. pellu- 
 cidum. Cells varying in length from four to eight times 
 their diameter. Spires serrated, three or four in number. 
 Granules large. 
 Z. rivulare Hassall, in Annals of Nat. Hist. vol. x. p. 38. 
 
 Dill. t. 4. A. B. 
 Hab. In the Barge, New, and Lea rivers, near Chesliunt, 
 abundant : A. H. H. Cader Idris : Mr. RaJfs. 
 
 This is a very distinct species, and certainly not the 
 Conjugata adnata of Vaucher, the filaments of which equal 
 nearly those of Z. nitidum in diameter. I have never been 
 so fortunate as to find it in a state of reproduction. It would 
 not appear to be common, as I have not received it from any 
 other of my correspondents save Mr. Ralfs. 
 
 b. Spires tivo in number in each cell. 
 
 11. ZyGNEMA DECIMINU3I Ag. 
 
 Plate XXIII. Figs. 3, 4. 
 
 Char. Filaments rather smaller than those of Z. neglectum. 
 Cells twice or thrice as long as broad. Spires two, crossing 
 each other. Granules large. Sporangia oval, obtuse, not 
 producing inflation of the cells in which they are lodged. 
 
ZYGNEMA. 145 
 
 Conf.jugalis Dillw. t. 5. ; and C. nitida, t. 4. f. A. B. Z. 
 
 deciminum Harvey, 1. c. p. 362. ; also in Manual, p. 143. 
 
 Hab. Chcsliimt and Epping Forest: A. II. H. In a 
 
 jjond between Eamslye Rocks and Broadwater Forest ; 
 
 Henfield Common ; and In a pond at Hill Park, near 
 
 Westerham, Kent : BIr. Jcnner. 
 
 This is a very j^retty species, and also very distinct, the 
 
 crosses described by the spires at once serving to distinguish 
 
 it from all others belonging to this division of the genus 
 
 Zygncma. Filaments frequently almost black. 
 
 c. Spires single. 
 
 12. Zygnema quininum Ag. 
 Plate XXVIII. Figs. 1, 2. 
 
 Char. Filaments of rather larger diameter than those of 
 Z. deceminitm. Cells longer than broad, '^^ivc j) erf or ming 
 about three revolutions iyi each. Sporangia acutehj oral, not 
 j)roducing inflation of the cells in ichich they are lodged. 
 Cuifervaporticalis JMiiller, Nova Comment. Petropolitana, 
 pars 3. p. 90. Conjugata porticalis Vaucher, Hist, des 
 Conf. ]A. 5. fig. 1. ; Dillw. t. 3. lower figure. 
 Hab. Everywhere common throughout Britain. 
 
 " Tliis conjugata, already described and observed by 
 IMiiller, is perha23S the most common of all those of the same 
 family ; its spires are formed of brilliant grains united by a. 
 thread or a tube. IMiiller compares them to porticos, since 
 in a certain state of their developement they have the form of 
 a semi-ellipse." — Vaucher. The specific name of quininum 
 bestowed upon them by Agardli is intended to express as well 
 as Miiller's of porticale, which ought properly to have been 
 retained on account of Its priority, the form described by 
 each turn of the spires. 
 
 13. Zygnema varians Ilass. 
 Plate XXIX. Figs. 1, 2, 3, 4. 
 
 Char. Filaments of someichat less diameter than those of 
 
146 CONJUGATEiE. 
 
 Zygnema quininum. Cells usually twice as long as broad. 
 Sporangia ovqJ, .atid not usually 'producing any inflation of 
 the receiving cell. 
 Hah. Cheslmnt and Its vicinity : A. H. H. At Hawk- 
 hurst ; in a pond in a cottage garden between Broom- 
 hill and Speldhurst ; and by the road-side near Black- 
 boy's toll gate : Mr. Jenner. Graham Castle : Major 
 Martin. 
 
 " This common species was formerly (see * Annals and Ma- 
 gazine of Natural History,' vol. x. p. 35.) passed over by me 
 as a variety of Z. quininum, from which I am now perfectly 
 satisfied that it is specifically distinct. When a number of 
 cells unite in regular order with those of a neighbouring 
 filament, no inflation of any of these occurs ; but it fre- 
 quently happens that several adjoining cells of a filament for 
 some reason or other do not unite, although the remaining 
 ones in that filament do ; in which case, those which have not 
 yoked themselves swell up, assuming a moniliform apjjear- 
 ance, and at the same time frequently emit blind and irregular 
 processes or prolongations, by which the cells manifest the 
 strong tendency which they have to conjoin themselves, but 
 which some cause, not evident, would appear to have frus- 
 trated. In some specimens, the number of inflated cells and 
 blind processes is but small, while in others the elongated 
 cells are more numerous than those w'hich have united in the 
 ordinary manner of the Zygnemata.^^ — MS. 
 
 14. Zygnema iESTivuM Ilass. 
 Plate XXVIII. Figs. 3, 4. 
 
 Char. Filaments of less diameter than those of Z. varians. 
 Cells usually about four times as long as broad, hut some- 
 times much longer, and occasionally shorter. Sporangia 
 oval, not producing any inflation of the cell in ichicli they 
 are formed. 
 Zygnema (sstivum Hassall, in Ann. Nat. Hist, vol.xi. p. 433. 
 Hah. Cheslmnt : A. H. H. Wadhurst ; and Bury, near 
 Arundel : Mr. Jenner. 
 
ZYGNEMA. 147 
 
 This species is clistinguislied from the former by the smaller 
 size of the filaments, greater length of the cells, and peculiar 
 zigzag disposition of the spiral thread ; it is not, however, a 
 very strongly marked species. 
 
 15. Zygnema malpormatum Ilass. 
 
 Plate XXX. Figs. 1, 2. 
 
 Char. Filaments nearly equal in diameter to those of Z. a;s- 
 tivum. Cells about twice as long as broad, in each of 
 which a single spiral thread performs usually two revolu- 
 tions. Sporangia acutely oval, lying obliquely in the cells, 
 ivhich are considerably distorted for their accommodation. 
 
 Zygnema malformatuni Hassall, In Annals of Nat. Hist. 
 vol. X. p. 39. 
 
 Hah. Cheshimt : A. H. H. In a pond at Still Green, 
 and In the watercourse by the road side, near the Black - 
 boy's toll-gate : Mr. Jenner. 
 
 I hesitated at first to regard tliis species as distinct from 
 Z. commune ; I now, however, entertain no doubt of the fact. 
 It is a very pretty species, and not uncommon. The form 
 of the cells is very distinct from that of Z. commune. 
 
 16. Zygnema CATEXiEFORME Hass. 
 
 Plate XXX. Figs. 3, 4. 
 
 Char. Filaments a little finer than those of Z. mnlformatum. 
 Cells usually rather more than ticice as lo7ig as broad. 
 Sporangia largely iiflating the cells in which they are con- 
 tained, acutely oval. 
 
 Z. catenaforme Hassall, in Ann. of Xat. Hist. vol. x. \). 39. 
 Ilab. "Cheshunt: A. H. H. Between Yapton and AVal- 
 berton near Arundel : il/r. Jenner. 
 
 It Is scarcely possible to distinguish the filaments of this 
 r. 2 
 
148 conjugatete. 
 
 species from those of Z. commune before conjugation : after 
 this has occurred, the difference in the length of the cells and 
 the form of these is so obvious as not to leave any doubt of 
 its being distinct from that species. To this species ought, I 
 think, the Zygnema brevissi7num, described by me in vol. x. 
 p. 40. of the " Annals of Nat. Hist." to be referred. I am still 
 not sure, however, but that it Is distinct, yet fear to regard It 
 as such. The cells in it are scarcely so long as broad ; the 
 sporangia broadly oval, sometimes almost circular, their long 
 diameter being placed transversely in the cells, which are 
 frequently highly inflated. 
 
 17. Zygnema commune Hass. 
 
 Plate XXVIII. Figs. 5, 6. 
 
 Char. Filaments about equal in diameter to those of Z. cate- 
 nceforme. Cells usually three times as long as broad. Spo- 
 rangia acutely oval, not occasioning any inflation of the 
 cells in which they are formed. 
 
 Zygnema commune Hassall, in Annals of Nat. Hist. vol. x. 
 p. 39. ; Dillw. t. 3. upper figure, in part ? 
 
 Hab. Cheshunt : A. H. H. Framfield Common : Blr. 
 Jenner, Parldnd Quarry : Alajor Martin. 
 
 This is a very distinct and regular species. 
 
 18. Zygnema gracile Hass. 
 
 Plate XXX. Figs. 5, 6. 
 
 Char. Filaments of less diameter than those of Z. commune. 
 Cells usually four times as long as broad, and inflated on 
 the side ichich gives origin to the tubes of communication. 
 Sporangia acutely oval, not rendering the cells at all vcn- 
 tricose. 
 
 Hab. Wanstead Flats, Essex ; Cheshunt : A. H. H. 
 
 Apparently a distinct species, known from Z. commune by 
 the smaller size of the filaments and lateral enlargements of 
 the cells. 
 
ZYGNEMA. 149 
 
 19. Zygnema flavescens Hass. 
 Plate XXX. Figs. 9, 10. 
 
 Char. Filaments of less diameter than those of Z. catena- 
 forme. Cells usually four times as long as broad, and 
 slightly inflated for the accommodation of the sporangia, 
 which are oval. 
 Hah. Hertford Heath; High Beech, Essex: A.H.Il. 
 Several places in Sussex and I'il^cnt : Mr. Jenner. 
 
 The only species with which this could be confounded are 
 Z. catcnaforme and Z. parvum, between which it is interme- 
 diate. It seems to prefer, like several other species of the 
 genus, the boggy pools of heaths, &c., to roadside ponds and 
 ditches. 
 
 20. Zygnema parvum Hass. 
 Plate XXX. Figs. 7, 8. 
 
 Char. Filaments more slender than those of the jjreceding 
 sjMcics. Cells rather more than four times as long as 
 hroad. Sporangia oval, generally producing a slight in- 
 flation of the cells in which they are foryned. 
 
 Zygnema parvum Hassall, in Ann. Nat. Hist. vol. x. p. 41. 
 
 Hah. Cheshunt : A. H. H. In a pond between Ramslye 
 Rocks and Broadwater Forest : Mr. Jenner. 
 
 This is one of the smallest species of the genus ; it is not 
 uncommon. 
 
 ** Extremities of CQ\h inverted. 
 
 21. Zygnema Grevilleanum Hass. 
 
 Plate XXXI. . Figs. 1, 2. 
 
 Char. ■ Filaments of rather less diameter than those of Z. 
 
 curvatum. Cells usually six or seven times as long as 
 
 hroad, round the interior of each of n-hich jcinds generally 
 
 one and sometimes ttco spiral threads. Sporangia hroadly 
 
150 CONJUGATED. 
 
 oval, lying in cells wliicli are considerably inflated for 
 
 their accommodation. 
 Zygnema Grevilleanum, Annals and Mag. of Nat. Hist. 
 
 vol. X. p. 38. 
 Hah. Cheshunt and Its vicinity : A. H. H. Framfield : 
 
 Mr. Jenner. Dolgelley : Mr. Ralfs. Turf Dyke, near 
 
 Ardrossan : Major Martin. 
 
 " To this fine species I have assigned the name of Dr. 
 Greville, author of the excellent * Alga3 Britannica;/ as a 
 slight mark of personal respect, as well as an acknowledge- 
 ment of the eminent services rendered by that gentleman 
 to natural history." 
 
 22. Zygnema in^equale Hass. 
 Plate XXXIT. Figs. 1, 2. 
 
 Char. Filaments of smaller diameter than those of Z. Gre- 
 villeanum.. Cells about Jive times as long as broad, and 
 enlarged on the side from tchich the tubes of communica- 
 tion arise. Sporangia oval. 
 Bab. Cheshunt: A. H. H. 
 
 This is not a common species. I have no doubt but that it 
 is distinct. 
 
 23. Zygnema sxjbventricosum Hass. 
 
 Plate XXXII. Figs. 3, 4, and 5. 
 
 Char. Diameter of the filaments about equal to these of 
 Z. commune. Cells usually Jive or six times as long as 
 broad. Sporangia oval, occasioning the cells in which they 
 are placed to assume a ventricose form. 
 
 Zygnema ventricosimi Hassall, in Annals of Nat. Hist, 
 vol.x. pp.38, 39. 
 
 Hah. Cheshunt and its vicinity : A. H H. Heathfield ; 
 in a pond near Boar's Head, Ramslye Rocks; and 
 
ZYGNEMA. 151 
 
 Rackham, near Pulborougli : Mr. Jenner. Dolgelley : 
 Mr. Ralfs. Parkind : Major 3Iartin. 
 
 This is a very distinct, as well as common species; that 
 wliicli I regard as a variety of it occurs at Wanstead Flats, 
 Essex, in which the filaments are somewhat finer, the cells 
 considerably longer, and the sporangia smaller. This may 
 be distinct. 
 
 24. Zygnema longatum Hass. 
 
 Plate XXXI. Figs. 3, 4. 
 
 Char. Filaments about equal in diameter to those of Z. suh- 
 ventricosum. Cells usually eight times as long as broad. 
 Sporangia not jiroducing any inflation of the cells, in 
 which they are formed. 
 Conferva punctalis Miiller, Flor. Dan. pi. 1. no. 1. Con- 
 jugata longata Vaucher, Hist, dcs Conf. pp. 71, 72. 
 plate 6. fig. 1. ; Dillw. t. 3. upper figure in part? Z. 
 (Bquale Hassall, in Annals of Nat. Hist. vol. x. p. 39. 
 Hah. Cheshunt, rare : A. H. H. In a pond between 
 Pembury and Lamberhurst Quarter : Mr. Jenner. 
 
 I have but little doubt of the correctness of the synonymcs 
 quoted ; the cells are never inflated. " II n'y a rien de jjIus 
 elegant ct de plus gracieux au microscope que cette jolic 
 conjuguee." — Vaucher. 
 
 25. Zygnema inflatum Hass. 
 
 Plate XXXII. Figs. 6, 7, and 8. 
 
 Char. Filaments of 7nuch less diayneter than those of Z. sub- 
 ve7itricosum. Cells usually four, five, or six times as long 
 as broad. Sporangia elongated, and lodged in cells ichich 
 become considerably inflated for their reception. 
 
 Conjugata inflata Vaucher, Hist, dcs Conf. p. 68. plate 5. 
 fig. 3. Zygnema varians Hassall, in Annals of Nat. Hist, 
 vol. xi. p. 431. 
 
152 CONJUGATED. 
 
 Hab. Chesliunt and vicinity : A. II. 11. Rusthall Com- 
 mon ; between Sharp's Bridge and Piltdown Common ; 
 Henfield: Mr. Jenner. Turf Dyke, near Ardrossan: 
 Major Martin. 
 
 I have now ascertained that the Zygnema varians described 
 by me in the "Annals of Nat. Hist." voh xi. p. 431., is 
 the Conjugata inflata of Vaucher, a species which I have 
 been long anxious to identify. I have recently met with 
 what I shall describe as a variety of this species, but which 
 may possibly be distinct. It is characterized as follows : — 
 
 var. a. — Filaments of the same diavieter as those of the 
 species proper. Cells eight or ten times as long as broad, 
 and enlarged on the side tchich gives origin to the tubes 
 of communication. Sporangia oval, long. 
 
 26. Zygnema tenuissimum Hass. 
 Plate XXXII. Figs. 9, 10. 
 
 Char. Filaments more slender than those of Z. injlatum. 
 Cells eight or nine times as long as broad. Sporangia pro- 
 ducing a slight inflation of the receiving cells. 
 
 ■ Zygnema tenuissimum Hassall, in Annals of Nat. Hist, 
 vol. X. p. 41. 
 Hab. Cheshunt : A. II. H. Belmonden, Hawkhurst : 
 3Ir. Jenner. Parkind : Major Martin. 
 
 This species bears a very close resemblance to the preced- 
 ing, from which it is chiefly distinguished by its smaller size. 
 
 Second Subgenus. — Filaments not conjugating. 
 
 * Cells ?iot ijiverted. 
 
 a. Spires si7igle. 
 
 27. Zygnema rostratum Hass. 
 
 Plate XXXIII. Fig. 1. 
 
 Char. Filaments of someichat larger diameter than those of 
 Zygnema nitidum. Cells from half to once as long as 
 
ZYGNEMA. 153 
 
 broad, spires numerous, granules small. Sporangia 
 broadly oval, sometimes almost circular, lying obliquely 
 in the cells, which arc not injiated. 
 
 Z. rostratum Hassall, MSS. 
 
 Hob. Pond, near Ilounslow : A. H. II. 
 
 A very fine species, tlie largest of all the non-conjugating 
 Zygnemata. It is very rare, for I have only once encoun- 
 tered it. 
 
 28. Zygnema Woodsii Hass. 
 
 Plate XXXIII. Fig. 1. 
 
 Char. Filaments of somewhat less diameter than those of 
 Zygnema qidninum. Cells usually about half or tivo- 
 thirds as long as broad. Sporangia oval, lying obliquely 
 in the cells, which are enlarged on that side from ichich 
 the tubes of communication j)rocced. 
 
 Z. Woodsii Hassall, MSS. 
 
 Hab. Cheshunt and neighbourhood : A. II. II. Several 
 places in Sussex and Kent : Mr. Jcnner. 
 
 On looking over Dillwyn's " Synopsis of British Conferva," 
 I was surprised to find under the head of Conferva spiralis 
 the following notice of the species just characterized : — 
 
 " Since the Introduction was printed, a curious specimen 
 of this species has been gathered by INIr. Home of Clapham, 
 and examined by INIr. Woods, who gives the following ac- 
 count of it. ' The plant is a pale dirty green, nearly with- 
 out gloss, about the size of C. sjnralis ; when magnified the 
 length of the joints is seen to be about equal to their width, 
 or a little more, and the spiral tube is in most parts nearly 
 obliterated ; but tlie chief singularity of this plant is in the 
 connecting processes, which are uniformly at the ends instead 
 of as usual in the middle of the joints, and each of which 
 appears to unite with the process of the next joint of the 
 same filament. No indication of the conjugation of two 
 filaments is to be observed ; the dark globules appear only 
 when the two joints are thus connected, and the adjacent 
 one is invariably empty.'" — Synojms, p. 60. 
 
154 CONJUGATED. 
 
 The above Zygnema, which Mr. Woods has so accurately 
 described, is also the variety of Z. quininum (C spiralis), 
 referred to by me in the 10th vol. of the " Annals," p. 35. I 
 have now, however, had numerous opportunities of examin- 
 ing it in all stages of its developement, and have no doubt 
 about the propriety of separating it from that species from 
 which it is distinguished by its finer filaments, and shorter 
 .cells, as well as by the manner in which the sporangia are 
 formed ; characters which are constant. 
 
 29. Zygxema alternatum Hass. 
 
 Plate XXXIII. Fig. 3. 
 
 Char. Filaments considerably finer than those of Z. JVoodsii. 
 Cells usually two and a half times as long as broad. 
 Sporangia oval, not producing any infiation of the re- 
 ceiving cell. 
 Hah. Cheshunt: A. H. H. 
 
 I have seen this but once : it may possibly be but a variety 
 of the preceding species, although I can scarcely suppose that 
 it is so. 
 
 30. Zygnema abbreviatum Hass. 
 
 Plate XXXIV. Fig. 4. 
 
 Char. Filaments about equal to those of Zygnema commune 
 in size. Cells once, or once and a half as long as broad. 
 Sporangia oval, small, not producing any infiation of the 
 cells in which they are lodged. 
 Hab. Cheshunt: A.H.H. 
 
 This also I have only once met with. It appears distinct, 
 however. 
 
 31. Zygnema angulare Hass. 
 
 Plate XXXIV. Figs. 1, 2, 3. 
 
 Char. Filaments at first straight, but at the period of repro- 
 
ZYGNEMA. 155 
 
 duction becoming angulated, the angles being situated at 
 the junction of the cells and produced by the tubes of com- 
 munication. Cells usually three times as long as broad. 
 Sporangia oval, producing considerable inflation of the re- 
 ceiving cell. 
 
 Zygnema angulatum Hassall, in Annals of Nat. Hist, 
 vol. X. p. 41. 
 
 Hab. High Beech, Essex; and Chcshunt: A. IT. II. 
 Mayfield, between Sharp's Bridge and Piltdown Com- 
 mon ; Barcombe and Framfield : Mr. Jcnner. 
 
 The angular disposition of the filaments at the period of 
 reproduction is not peculiar to tliis species, the filaments 
 of most other non-conjugating Zygnemata being also angular 
 at that period. A variety of this species has occurred to 
 me, having cells only once and a half, or twice as long as 
 broad. 
 
 32. Zygnema malleolum Ilass. 
 Plate XXXIV. Fig. 5. 
 
 Char. Filaments of nearly the same diameter as those of 
 Zygnema parvum. Cells usually about six times as long 
 as broad. Sporangia producing considerable inflation of 
 the cells. 
 Hab. Cheshuut: A. H. H. 
 
 This would appear to be a distinct species, differing from 
 the following in the much greater length of the cells. The 
 empty cell taken in connection with the fruit-bearing cell 
 resembles somewhat in outline a hammer. 
 
 33. Zygnema affine Hass. 
 Plate XXXIV. Fig. 6. 
 
 Char. Filaments of nearly the same diameter as those of 
 Zygnema parvum. Cells usually tivice or twice and a half 
 as long as broad. Sporangia oval, lodged in cells, ichich 
 are considerably inflated. 
 Hah. Chcshunt: A. H. H. 
 
156 CONJUGATED. 
 
 I have only once met with this. If a condition of any, it 
 must be of the preceding species. 
 
 b. Sporangia formed in every cell. 
 
 34-. Zygnema mirabile Hass. 
 Plate XXXV. Figs. 1, 2, 3. 
 
 Char. Filaments equal to those of Z. commune in diameter. 
 CeUs about six times as long as broad. Sporangia oval, at 
 first much elongated, and finally producing a slight in- 
 flation of the cells. 
 Z. mirabile Hassall, MSS. 
 
 Hah. Cheshunt and its vicinity : A. H. H. In the pond 
 between Tunbridge Wells Common and the Hurst 
 AYood ; in a pond at Burwash : Mr. Jenner. 
 
 This remarkable Zygnema I have repeatedly met with in 
 the state in which I have described it, and which I believe to 
 be its perfect condition. Mr. Jenner states that he is con- 
 vinced that the cells are united, but that the connecting 
 tubes are so frail as usually to be destroyed before the 
 specimen Is examined. Mr. Jenner's observation, however, I 
 feel assured applies not to Z. mirabile, but to some other 
 species; for had the cells at any period been united, they 
 would have been clearly indicated, even in the absence of the 
 connecting tubes, by the occurrence of empty cells in number 
 equal to those which contained sporangia. Now I have said 
 that in this species all the cells contain sporangia. 
 
 ** Extremities 0/* cells inverted. 
 
 a. Spires two. 
 
 35. Zygnema Hassallii Jenner. 
 
 Plate XXXVI. Figs. 4, 5. 
 
 Char. Filaments of nearly the same diameter as those of 
 
 Zygnema Grevilleanum. Cells five or six times as long 
 
 as broad. Spires two, laxly disposed, and crossing each 
 
ZYGNEMA. 157 
 
 other. Sj^orangia oval, large, and producing a considerable 
 injlation of the cells in which they are lodged. 
 
 Zygnema Hassallii Jenncx', in Flora of Tunbridge AVells, 
 p. 182. 
 • Ilab. Chcshunt and Notting Hill : A. H. IL Sandhurst ; 
 near tlic rock at Washington ; and at Hellingly : Mr. 
 Jenner. 
 
 J\Ir, Jenner has done me the honour to assign my name to 
 the above species, which is one of the finest and most distinct 
 of the Zygnemata. I encountered it several times during the 
 spring and summer of 1842, but not liaving then met with 
 it in a state of reproduction, I regarded the filaments as those 
 of Z. Grevilleanum, which, however, are usually furnished 
 but with a single spire, and in which the form of the conju- 
 gated cells is so different. 
 
 b. Spire single. 
 
 36. Zygnema quadratum Ilass. 
 Plate XXXVII. Figs. 1, 2. 
 
 Char. Filaments of rather less diameter than those of Zyg- 
 nema Hassallii. Cells usually seven or eight times as long 
 as broad. Sporangia oval, large, and much elongated, 
 contained within quadrangular enlargements of the cells. 
 Tubes of communication prominent. 
 
 Zygnema quadratum Hassall, in Annals of Nat. Hist, 
 vol. X. p. 41. 
 
 Hab. High Beech ; Epping Forest ; Cheshunt; and other 
 places : A. H. H. Pond at Ramslye : Mr. Jenner. 
 
 This is one of the most distinct as well as curious of the 
 non-conjugating Zygnemata. It is by no means unconnnon. 
 
 37. Zy'GNEMA intermedium Hass. 
 
 Plate XXXVII. Fig. 3. 
 
 Char. Filaments of rather less diameter than those of Z. qua- 
 
158 C0NJUGATEJ5. 
 
 dratum. Cells about five times as long as broad. Sporangia 
 oval, and producing a slight hvflation of the cells. 
 
 Zygnema intermedium Hassall, in Annals of Nat. Hist, 
 vol. X. p. 41. 
 
 Hob. High Beech ; Cheshunt: A. H. H. Pond at Rams- 
 lye ; water-course by the road side at Wadhurst ; and in 
 a wet place in Tunbridge Wells Common : Mr. Jcnner. 
 
 This very distinct species might be readily mistaken for 
 Zygnema angulatum, from which, however, it is at once dis- 
 tinguished by the inverted cells ; which cells also are longer. 
 
 38. Zygnema diductum Hass. 
 
 Plate XXXVII. Fig. 4. 
 
 Char. Filaments about equal in diameter to those of Z. inter- 
 medium. Cells eight or ten times as long as broad. Spo- 
 rangia oval, producing very considerable inflation of the 
 cells in which they are lodged. 
 
 Ilab. Cheshunt: A.H.H. 
 
 There is but little doubt of the distinctness of this species. 
 
 39. Zygnema vesicatum Hass. 
 Plate XXXVII. Fig. 5. 
 
 Char. Filaments about equal in diameter to those of the pre- 
 ceding species, Z. diductum. Cells usually three times as 
 long as broad. Sporangia oval, producing a very consider- 
 able inflation of the cells in ivhich they are lodged. 
 The chief difference between this and the following spe- 
 cies consists in the more considerable size of the filaments. 
 
 40. Zy'GNEMA Jenneri Hass. 
 
 Plate XXXVII. Figs. 6. and 9. 
 
 Char. Filaments of less diameter than those of Z. vesicatum. 
 Cells usually three or four times as long as broad. Spo- 
 
ZYGNEMA. 159 
 
 rangla oval, lodged in cells, which are considerably in- 
 flated. 
 Hah. In a wet spot by the road side between Dudsland 
 toll-gate and the Hall Farm, Mayfield ; in the pond at 
 Kanislye; in the watercourse by the road side near 
 Mark Cross, &c. : Mr. Jcnner. Clieshunt : A. 11. II. 
 
 To this species, which is certainly a distinct one, I have 
 assigned the name of Mr. Jenner, whose zeal and acutcness 
 in the cultivation of a knowledge of the freshwater AlgcB, as 
 well as in the pursuit of other departments of Natural Histor}^, 
 are so eminent. I could have wished that it had been more 
 worthy to have borne his name ; it has one advantage, how- 
 ever, over some others, which is this, that it is an abundant 
 species. 
 
 41. Zygnema dubium Hass. 
 
 Plate XXXVII. Fig. 7. 
 
 Char. Filaments rather more slcjider than those of Z. Jcn- 
 neri. Cells Jive or six times as long as broad. Sporangia 
 oval, lo7ig, placed in cells, tvhich are inflated for their 
 reception. 
 Hah. Between Sldley Green and Xlnfield, near Battle : 
 Mr. Jenner. Near Wormly West End, Hertfordshire : 
 A. H. H. 
 
 This may be but a variety of Zygnema Jcnneri. 
 
 42. Zygnema minimum Hass. 
 Plate XXXVII. Fig. 8. 
 
 Char. Filaments as sle7ider as those of Z. tenuissimum. Cells 
 many times as long as broad. Sporangia oval, lodged in 
 much inflated cells. 
 Hah. Cheslnmt: A. H.H. 
 
 This possibly may not be distinct, but prove eventually to 
 be the unconjugated state of Z. tenuissimum. 
 
160 CONJUGATED. 
 
 11. TYNDARIDEA i?ory. 
 
 Char. Endochrome disposed in the cells in a star-like form, 
 the stellate masses being double in each cell. Sporangia 
 usually circidar, sometimes lodged in the cells, and occa- 
 sionally in the connecting titbes. 
 
 Derivation. Tyndaridce, the constellation so called of Cas- 
 tor and Pollux ; in allusion to the twin star-like masses 
 contained in each joint. 
 
 . Stellulina Link, Handb. iii. 261. Agardhia Gray. Glo- 
 bulina Link, in Hor. Physic. 5. Lucernaria Kouss. 
 et Desv.j Jour. Bot. i. 143. TyndaridecR et Leda species 
 Boy J, in Diet. Class. Conjugatce, sect. 11. Vauch. pi. 6, 7. 
 
 The species of the genus Tyndaridea are distinguished by 
 the arrangement of the endochrome, which is in star-like 
 masses, two of which are contained in each cell, connected usu- 
 ally by a band or tube. Concerning the nature of these bodies, 
 numerous conjectures hare been hazarded. It has been sup- 
 posed that the one represented the male and the other the 
 female, the sporangia resulting from their union : this con- 
 jecture, however, does not seem probable. This form, as well 
 as the beautifully spiral arrangement of the endochrome, in 
 the genus Zygnema, has doubtless been impressed upon these 
 plants by the Deity, in order that they might appear the 
 more attractive and more w^onderful in the eyes of man. 
 
 The sporangia are usually circular, and lodged either in 
 the cells themselves, or in the transverse tubes. By this dif- 
 ference in the situation of the sporangia, the genus admits of 
 a natural division into two subgenera. 
 
 First Subgenus. — Sporangia 7J»Za<?(?(;? in the cells of one or other 
 filament. 
 
 1. Tyndaridea cruciata Ilass. 
 
 Plate XXXVIII. Fig. 1. 
 
 Char. Filaments of considerable size. Cells once or once and 
 a half as long as broad, at first densely filled icith en- 
 
TYNDARIDEA. 161 
 
 dochrome, lokich near the period of conjugation exhibits a 
 somcichat stellate arrangement. Sporangia circidar, not 
 producing any material change in the primary form of 
 the cell. 
 
 Conjugata cruciata Vaucher, Hist, cles Conf. pi. vi. fig. 4. ; 
 1)1. \ii. fig. 2. p. 77. 
 
 Hab. Cheslmnt: A. H. H. 
 
 I have but little doubt that this is the Conjugata cruciata of 
 Vaucher. It is the finest of all the Tyndaridece I have met 
 Avith. It is not common : and I have only once obtained it 
 with the sporangia formed. 
 
 2. Tyndaridea anomala Ralfs. 
 Plate XXXVIII. Figs. 2, 3. 
 
 Char. Filaments smaller than those of T. cruciata. Cells in 
 the young state usually about as long as broad, densely 
 filled tvith endochrome, and invested icith a broad and 
 very apparent mucous sheath; in a more advanced con- 
 dition the threads become narroioer, the sheath smaller, 
 and the endochrome more scattered, and sometimes even 
 stellated; finally, the sporangia are formed, rcldch are 
 circular, and protrude slightly into the tubes of commu- 
 nication of the filaments. 
 T. anomala Ealfs, MSS. 
 
 Hah. Penzance and Dolgelly : Mr. Ralfs. High Beech : 
 A. H. H. In a boggy spot near Cross in Hand, oppo- 
 site to where the road branches to Hailsham ; Barcombe, 
 in Sussex, and Weston Bogs, near Southampton: Mr. 
 Jenner. 
 This remarkable and somewhat anomalous species was first 
 discovered by INIr. Ralfs, who submitted it to the examination 
 of several friends. For a long time, however, doubts were 
 entertained by many as to whether it really was a Tynda- 
 ridea or not ; doulits which I myself, in common with others, 
 for a pei'Iod entertained, but which I was happily enabled to 
 
162 CONJUGATED. 
 
 terminate by the discovery of a specimen in which perfect 
 sporangia were formed. The filaments, when dried on paper, 
 exhibit less gloss than the other species of the genus, and the 
 endochrome contracts but little. When the sporangia are 
 formed, but little difference can be detected between its fila- 
 ments and those of the following species. Where the species 
 does occur, it is ordinarily very abundant, destroying most 
 other Conferv<2 with which it is in contact, by its more vi- 
 gorous growth. The highly developed mucous sheath, which 
 is so characteristic of the sj^ecies, frequently presents waived 
 and irregular margins. 
 
 3. Tyndaridea lutescens Hass. 
 
 Plate XXXVIII. Fig. 4. 
 
 Char. Filaments of nearly the same diameter as those of the 
 preceding species. Cells at first scarcely so long as broad, 
 a?id filled with endochrome; sxd)seqiiently they become longer 
 than broad; and then the endochrome j^resents a partial 
 division, each division being somewhat stelliform. Sporangia 
 circular. 
 
 T. cruciata Harv. in Manual, p. 141. 
 
 Hab. Cheshunt and its vicinity : A. H. H. 
 
 This is the species which until lately I have regarded as 
 the Conjugata cruciata of Vaucher, to which in all, save 
 size, it bears considerable resemblance. It appears to be the 
 commonest species of the genus ; but I am not able to refer 
 it to any of Vaucher's species. Tyndaridea abbreviata, An- 
 nals of Nat. Hist., vol. X. p. 43, I am now inclined to think 
 is but this species with cells shorter than ordinary. 
 
 4. Tyndaridea bicornis Hass. 
 
 Plate XXXVIII. Fig. 5. 
 
 Char. Filaments more slender than those of the preceding 
 species. Endoclirome divided iiito two masses, which are 
 united by a narrow band in the centre, each mass present- 
 ing two -points or horns on its distant extremity. Sporangia 
 
TYNDAEIDEA. 163 
 
 circular, contained within the cells. Cells usually rather 
 
 more than tivice as long as broad. 
 Tyndaridea hicornis, Annals of Nat. Hist. vol. x. p. 43. 
 Hab. Cheshunt and other places : A. H. H, 
 
 This species is by no means uncommon, and is certainly 
 distinct. A species described in the 10th vol. of the Annals 
 of Nat. Hist, under the name of T, iyiterposita, ought, I think, 
 to be regarded as a variety of the species. Fig. 8. plate 
 XXXVIII. may perhaps represent a species distinct from T. 
 bicornis. I have more than once met with it just as repre- 
 sented in the figure. 
 
 5. T. INSIGNIS Hass. 
 Plate XXXVIII. Figs. 6, 7. 
 
 Char. Filaments rather smaller than those of T. bicornis. 
 Cells ttvice as long as broad, and frequently curiously 
 distorted, that side of them tchich either has or is about 
 to unite itself ivith another, becoming remarkably protube- 
 rant. Sporangia circidar, and partly lodged in the trans- 
 verse tubes. 
 Hab. High Beech, Wanstead, and other places : A. H. H. 
 Rusthall Common ; in a pool by the road-side between 
 Cross in Hand and Heathfield ; pond near Five Ashes, 
 INIayfield ; on Watcrdown Forest ; Greatham and 
 Storriugton Commons : Mr. Jenner. 
 
 This species, which sometimes presents an appearance so 
 remarkable, was first sent me by JNIr. Jenner. It is by no 
 means uncommon, and I think certainly distinct from all 
 others with which I am acquainted. 
 
 6. Tyndaridea stagnalis Ilass. 
 
 Plate XXXVIII. Fig. 9. 
 
 Char. Filaments more slender than those of T. insignis. Cells 
 about two a?id a half times as long as broad. Sporangia 
 
164 CONJUGATED. 
 
 circular, extending into a portion of tlte connecting tubes. 
 
 T. stagnalis. 
 Hassall, in Annals of Nat. Hist. vol. x. p. 42. 
 Hab. Abundant on Hertford Heath and other places in 
 
 the counties of Hertfordshire and Essex: A. H. H. 
 
 Rusthall Common ; Waterdown Forest, and near Cross 
 
 in Hand. 
 
 This is a distinct and common species. Fig. 10. plate 
 XXXVIII. may possibly be distinct from this. 
 
 Second subgenus. — Sj^orangia lodged in the transverse tubes. 
 
 7. Ttndaridea immersa Ilass. 
 
 Plate XXXIX. Fig. 3. 
 
 Char. Filaments of considerable diameter. Cells about once 
 and a half or twice as long as broad. Endochrome dis- 
 tinctly stellate. Sjiorangia large, circular, and jjartly im- 
 mersed in the cells. 
 Tyndaridea conspicua. Annals of Nat. Hist. vol. xii. 
 
 p. 187. pi. 7. fig. 17. 
 Hab. Wimbledon Common : A. H. H. 
 
 " This species bears considerable resemblance to Vaucher's 
 figiu'e of T. pectinata. I do not think, however, that it is 
 that species, for I presume that Vaucher employed the same 
 magnifying power to all his figures ; in which case the fila- 
 ments of T. pectinata would be almost equal in diameter 
 to those of Z. quininum, and consequently nearly as large again 
 as those of the present species." — Annals. 
 
 8. Tyndaridea conspicua Ilass. 
 
 Plate XXXIX. Figs. 1, 2. 
 
 Char. Filaments ratlier smaller than those of the preceding 
 species. Cells usually twice, or twice and a half as long as 
 
TYNDARIDEA. 165 
 
 • broad. Sporangia usually sj^herical, but sometimes oval, 
 and entirely confined to the transverse tubes. 
 
 Tyndaridea immersa. Annals of Nat. Hist. vol. xii. p. 188. 
 pi. 7. fig. 19. 
 
 Hab. Wimbledon Common : A. H. H. 
 
 A very rare species. I have seen it but once. 
 
 9. Tyndaridea decussata Hass. 
 
 Plate XXXIX. Fig. 6. 
 
 Cliar. Filaments of less diameter than those of the preceding 
 species. Cells usually two and a half times as long as 
 broad. Sporangia circular, and a portion of them immersed 
 either in one or other, or both cells. 
 T. decussata Hassall, in Annals and Mag. of Nat. Hist. 
 vol. xii. p. 188. pi. 7. fig. 18. 
 
 The species described by Vaucher, under the head of Con- 
 jugata decussata, would appear to be referrible to the next 
 genus, and not to Tyndaridea. 
 
 10. Tyndaridea Kalfsii Hass. 
 Plate XXXIX. Figs. 4, 5. 
 
 Char. Filaments of less size than those of T. immersa. Cells 
 usually four times as long as broad. Sporangia elliptical, 
 their long diameter correspondiiig tvith the length of the 
 tube. 
 Hab. Penzance : Mr. Ralfs. Near Cross in Hand, oppo- 
 site to Avhere the I'oad branches to Hailsham, and on 
 Piltdown Common. 
 T. Ralfsii Hassall, in Annals of Nat. Hist. vol. xii. p. 188. 
 pi. 7. fig. 20. 
 
 " There is not a more beautiful or elegant species than 
 this in the genus, and I have much satisfaction in dedicating 
 it to INIr. Ralfs, its first finder, and a gentleman by whom 
 
166 CONJUGATEJi. 
 
 our knowledge of the AlgcB has been so considerably aug- 
 mented." — Annals, 
 
 12. MESOCAEPUS Hassall 
 
 Char. Cells JiUed at first loith endochrome, ivhich subsequently 
 contracts, and assujnes an irregularly spiral form. 
 Sporangia either circular or oval, and lodged in the trans- 
 verse tubes. 
 
 Derivation. From fiscros, middle, and Kaprros, fruit. 
 
 Sph<Brocarpus Hassall, in Annals of Nat. Hist. vol. xi. 
 p. 185. pi 7. fig. 7. &c. 
 
 The genus Mesocarpus, for which I first proposed the name 
 of SphcBrocarpus, to designate the position of the sporangia, 
 and which I now find to be preoccupied, difiers from the 
 two genera already described in not having the endochrome 
 arranged in any definite and figured form. When the fila- 
 ments are young, the endochrome occupies the entire cavity 
 of each cell ; as they grow older, however, spaces are left at 
 the extremities of the cells; and finally the endochrome 
 frequently contracts itself into a mere thread, irregularly 
 twisted. The sporangia are never placed in the cells, as in 
 all the species of the genus Zygnema, and in very many Tyn- 
 daridecB, but invariably in the transverse tubes of commu- 
 nication which become dilated for their accommodation. The 
 species of this genus live in water, less pure than the Zygne- 
 mata and Tyndaridece, being mostly found in boggy and 
 ancient ponds, on commons, &c. ; and on this account they 
 are rarely so brightly coloured as are the species of those 
 genera. 
 
 1. Mesocarpus scalaeis Hass. 
 
 Plate XLII. Fig. 1. 
 
 Char. Filaments exceeding someiohat in diameter those of 
 Mougeotia genufiexa. Cells about four times as long as 
 broad. Sporangia oval, their long diameter being placed in 
 the direction of the diameter of the cells. 
 
MESOCARPUS. 167 
 
 var. /?. — Sporangia circular. 
 
 Mougcotia scalaris Ilassall, in Annals and ]\Iag. of Nat. 
 Hist. vol. X. p. 45. pi. 7. fig. 7. Zygncma ordinarium ? 
 Berkeley's Gleanings. Sjyhcerocarjms scalaris var., An- 
 nals of Nat. Hist. vol. xii. p. 186. pi. 7. fig. 8. 
 
 Half. England ; common, var. /?, Crowboroiigh Warren : 
 Mr. Jenner. 
 
 This is one of the commonest as well as most distinct 
 species of the genus. I have encountered it repeatedly myself, 
 and have also received it from JNIr. Jenner. Z. ordinarium 
 Berkeley is quoted as a synonyme with considerable doubt ; 
 but if that species be not the one above described, I am at 
 a loss to which of the otlier species of the genus described in 
 this paper it ouglit to be referred. The filaments in 3Icso- 
 carpus scalaris, as well as in the majority of the otlier species 
 of genus, are of a yellowish green, owing to the greater 
 impurity of the water in which they dwelt. 
 
 Plate XLii. fig. 2. represents what I shall here describe 
 as a variety of this species. The filaments are of the same 
 diameter, but the sporangia, instead of being oval, are spherical. 
 It is very probable that this is really a distinct species ; but 
 having seen it but once, I hesitate so to regard it. 
 
 2. MeSOCARPUS INTRICATUS Hass. 
 
 Plate XLIIL Fig. 1. 
 
 Cliar. Filaments smaller than those of M. scalaris. CeWsJive 
 
 or six times as long as broad. Sporangia oval, rather 
 
 larger than those of M. scalaris, their long diameters being 
 
 placed in the direction of the ividth of the cells. 
 
 Sphcerocarjms intricatus. Annals of Nat. Hist. vol. xii. 
 
 p. 186. plate 7. fig. 9. 
 Hah. Broadwater Forest : Mr. Jenner. 
 
 The only differences to be detected between this and 31. 
 scalaris are, the smaller diameter of the filaments, and 
 
168 CONJUGATED. 
 
 greater size of the sporangia ; but these are, I think, of a 
 sufficiently well marked character to justify its being ranked 
 as a distinct species. It has only as yet been found by that 
 indefatigable observer IMr. Jenner. 
 
 3. Mesocarpus recurvus Hass. 
 
 Plate XLIII. Fig. 2. 
 
 Char. Filaments smaller than those of M. intricatus. Cells 
 six or seven times as long as broad. Sporangia circular. 
 Sjihcerocarpus recurvus Hassall, in Annals of Nat. Hist. 
 
 vol. xii. p. 186. plate 7. fig. 10. 
 Hah. Penzance : Mr. Ralfs. Eackham Common : Mr. 
 Jenner. 
 
 " This species I first received from Mr. Ralfs, and some 
 two or three weeks afterwards it was sent me by Mr. Jenner. 
 I regard, it however, as the species figured by Dillwyn (Sup- 
 plement, plate C), as 31. genujlexa in a state of repro- 
 duction." — Annals. 
 
 4. Mesocarpus depressus Ilass. 
 
 Plate XLIV. Fig. 1. 
 
 Char. Filaments rather larger than those of Alesocarpus 
 
 recurvus. Cells six or seven times as long as broad. 
 
 Sporangia oval, small, their long diameter being placed in 
 
 the direction of the length of the cells. 
 
 Sphcerocarjnis depressus Hassall, in Annals of Nat. Hist. 
 
 vohxii. p. 186. plate 7. fig. 11. 
 Hah. In a boggy spot near Cross in Hand, opposite to 
 where the road branches to Hailsham: Mr. Jenner. 
 Penzance : Mr. Ralfs. 
 
 " There can be no doubt of the distinctness of this species, 
 which was procured by INIr. Jenner, some weeks before it 
 was found and transmitted me by Mr. 'Rv^ik.'" -"- Annals. 
 
MESOCARPUS. 169 
 
 5. Mesocarpus nummuloides Ilass. 
 Plate XLV. Fig. 1. 
 
 Char. Filaments of rather larger size tlian those of Meso- 
 carpus recurvus. Cells about six times as long as Iroad, 
 not usually recurved. Sporangia circular, and smaller than 
 those of M. recurvus. 
 Sph(27-ocarpus nummuloides Hassall, iu Annals of Nat. Hist, 
 vol.xii. ij. 187. plate 7. fig. 12. 
 
 Hah. Hertford Heath : A. H. H. 
 
 This species approaches very closely to the following. 
 
 6. Mesocarpus parvulus Hass. 
 Plate XLV. Figs. 2, 3. 
 
 Char. Filaments much shorter than those of Mesocarpus 
 
 nummuloides. Cells usualhj six times as long as broad. 
 
 Sporangia circidar, small. 
 Mougeotia parvula Hassall, in Annals of Nat. Hist. vol. xi. 
 
 p. 434. ; SphcBrocarpus parvidus Hassall, Annals, 
 
 vol.xii. p. 187. plate 7. figs. 13, 14. 
 Ilab. Hertford Heath, Epping, &c. ; A. II. H. Near 
 
 Cross in Hand and Waterdown Forest : Mr. Jcnner. 
 
 The larger figure of the two may represent a distinct 
 species. 
 
 7. Mesocarpus ovalis Hass, 
 Plate XLIV. Fig. 2. 
 
 Char. Filaments about equal in size to those of Mesocarpus 
 parvidus. Cells ten or twelve times as long as broad. 
 Sporangia slightly elliptical, their long diameter being 
 placed in the direction of the length of the cells. 
 Sphccj-ocajpus ovalis Hassall, in Annals of Nat. Hist, 
 vol. xii. p. 189. plate 7. fig. 15. 
 
 Hab. Hertford Heath : A.H. H. Penzance : Mr. Balfs. 
 
170 CONJUGATEiE. 
 
 " The sporangia, though elliptical, are not nearly so much 
 so as those of 31. depi-essus, and the filaments not one half 
 so large." — A^inals. 
 
 8. Mesocarpus angustus Hass. 
 
 Plate XLY. Fig. 4. 
 Char. Filaments very slender. Cells many times longer than 
 broad. Sporangia circular, very large in comparison with 
 the size of the filaments. 
 Sph(Brocarpus angustus Hassall, in Annals of Nat. Hist. 
 
 voLxii. p. 187. plate 7. fig. 16. 
 Hah. Penzance : JSIr. Ralfs. 
 
 " This is a very distinct species, and for its discovery we 
 are indebted to Mr. Ralfs." — Annals. 
 
 Sporangia formed tvithout union of the filaments, or com- 
 mingling of the contents of two cells. 
 
 9. Mesocarpus notabilis Hass. 
 
 Plate XL VI. Fig. 2. 
 
 Char. Filaments at first cylindrical, hut subsequently be- 
 coming angulated, the angle of fiexion being situated in 
 the centre of each cell. Cells usually about eight or ten 
 times as long as broad, but frequently longer. Sporangia 
 non-symmetrical, a single one being placed in the angle 
 formed in each of the cells. 
 Mougeotia notahilis Hassall, in Ann. Nat. H. vol. x. p. 46. 
 
 Hah. Found in great abundance in some brick-fields near 
 Netting Hill : A. H. H. 
 
 I am unwilling to create a new genus for the reception of 
 this curious and anomalous production, and am induced to 
 refer it to Mesocarpus, on the supposition that were the fila- 
 ments in any case to conjoin, and sporangia to be formed, 
 that these would present the characters of the genus, and be 
 either spherical or oval. 
 
MOUGEOTIA. 171 
 
 13. MOUGEOTIA Ag. 
 Char. Filaments coalescing usually ivithout the intervention 
 of transverse tubes ; no transference of cndochrome, and 
 no formation of sporangia taking place. Conjugation ««- 
 gular. 
 
 Kamed in honour of M. J. B. Mougeot, a German botanist. 
 
 The genus Mougeotia coiTcsponds with Mesocarpus, save in 
 the important fact that, although the filaments conjoin, there 
 is no transference of endochrome, and consequently no form- 
 ation of sporangia. 
 
 The following account of the genus Mougeotia was inserted 
 in the " Annals and INIagazine of Natural History : " — 
 
 " The real nature of the genus Mougeotia does not liitlierto 
 appear to have been at all understood, and consequently the 
 definitions given of it up to the present time are either erro- 
 neous or incomplete. 
 
 " Vaucher thus defines the genus Mougeotia : — ' Conjugees 
 a tube interieur.' And Agardh, as follows : — ' Fila articulata 
 reticulata conjuncta, granulis absque ordine dispositis, fructibus 
 in angulis rcticidi collocatis.^ 
 
 " The first of these definitions is imperfect, and the second 
 inaccurate, inasmuch as it contains a reference to perfect 
 fructification distinct from the granules or zoospores. 
 
 " The true and original species of the genus Mougeotia are 
 all characterized by the singular fact, that sporangia, which 
 Agardh calls the fruit, are never found in them as they are in 
 all other species of the conjugating tribe of Conferva. The 
 filaments do indeed unite, but no transference of the con- 
 tents of one cell into the interior of the other, and conse- 
 quently no formation of sporangia ever take place. 
 
 " This remarkable circumstance in the history of the genus 
 Mougeotia, resting as it does on long-continued and careful 
 observation of the species composing it, docs not admit of the 
 smallest doubt ; and although not absolutely stated as a fact, 
 it is yet strongly implied by Vaucher in his description of Mou- 
 'geotia genujiexa, in which the following observations occur : — 
 
 " ' This Conjugata has not presented to me the round 
 
172 CONJUGATED. 
 
 globules of the other species of the same family ; on the con- 
 trary, the green matter Avhich it incloses has appeared to 
 me to present nearly the same form, so that I know not how 
 the grain is formed, nor in what way the derelopement in this 
 species is brought about ; only I have remarked distinctly 
 three or four bright grains immersed in this green matter, 
 and I have seen in the month of Ajjril the cells separate 
 from each other and sink in the water, but I traced them no 
 further. Nevertheless, I have difficulty in believing that the 
 brilliant grains are not the germs. 
 
 " ' Since writing this description I have seen the germin- 
 ation of this Conjugata elsewhere in a manner very different 
 from all the others : the matter does not pass from one tube 
 to another neighbouring tube, but each cell Itself furnishes 
 a single young plant, the Interior tube which it was found to 
 enclose becoming a young Conjugata which was entirely con- 
 tained in the old tube, as it itself contains the plants which 
 are afterwards to become developed ; it issues by the ex- 
 tremity when it occupies the last cell, and by the sides when 
 it is found in one of the central cells.' 
 
 " With respect to the observations of Vaucher in reference 
 to the germination of the young Conferva while still within 
 the parent cell, I would observe that I have never witnessed 
 this singular developement, and can confidently assert that 
 this is not the legitimate or normal mode of developement of 
 the species of the genus Mougeotia, which is by zoospores, de- 
 veloped external to the cells, as in other Conferva'' 
 
 1. MOUGEOTIA MAJOR Ilass. 
 
 Plate XL. Fig. 1. 
 
 Char. Filaments of considerable size. Cells usually five times 
 
 as long as broad. 
 JSIougeotia major Hassall, In Annals of Nat. Hist. vol. x. 
 
 p. 44. 
 Hab. Cheshunt : A. H. H. 
 Either this species and the following are subject to very 
 
MOUGEOTIA. 173 
 
 considerable variation, or else several species, really distinct, 
 have been improperly referred to them. At one time, enter- 
 taining the latter opinion, I was induced to add three otlier 
 species to the genus ; but not finding, on subsequent examina- 
 tion, that these species were well established, I shall omit all 
 mention of them in the present work. 
 
 2. MoUGEOTIA GENUFLEXA A^. 
 
 Plate XL. Fig. 2. 
 
 Char. Filaments q/*smo//er diameter than those of M. major. 
 Cells seven or eight times as long as broad. 
 Miiller, Acta Petropolitana, pars 3. p. 92. pi. 1. fig. 9. 
 Conjugata angulata Vaucher, Hist, des Conf. p. 79. 
 pi. 8. figs. 1, 2, 3, 4. 
 
 This interesting species is one of the commonest of the 
 Avholc tribe of freshwater Conferva, and there is scarce a 
 ditch in which it may not be found at all seasons of the year 
 The tubes remain connected for a very long time after con- 
 jugation, and this explains why it is that the species should 
 so constantly be found united. For Vaucher's account of its 
 reproduction sec page 172. 
 
 14. ZYGOGONIUINI Kutzing. 
 
 Char. Filaments of equal diameter, rarely branched. Cells 
 seldom conjugating ; transference of endochrome rare. 
 Sporangia none. Endochrome at first filling the cavity 
 of the cell. Zoospores scattered without order through the 
 colouring matter. 
 Derivation. From ^^705-, a yoke, and ^wvia, an angle. 
 
 This genus seems to me to be well established. At first 
 I felt disposed, on perceiving that the filaments of C. erice- 
 torum were occasionally branched, to refer the species to the 
 branched Conferva, acknowledging, at the same time, that in 
 many points it resembled the conjugating AlgcB. Subse- 
 quently, on finding union to have taken place between some 
 
174 CONJUGATED. 
 
 of the filaments, I felt satisfied that its proper place was 
 with the Conjugate<2, and referred it to Mougeotia. This 
 reference did not, in all respects, seem satisfactory, for while 
 the true species of Mougeotia are almost constantly found 
 united, C ericetoriim is very rarely met with in that con- 
 dition. So rarely, indeed, as to make it apparent that the 
 species is reproduced independent of any union of the fila- 
 ments. The habit of C. ericetoriim was so difterent from 
 that of the true Mougeotia, being more that of a Scytonema, 
 that I had determined to place it in a genus by itself ; a step 
 which, on looking over Kiitzing's " Phycologia Generalis," 
 I found to have been already taken. Kiitzing thus accu- 
 rately defines the genus : — 
 
 *' Trichomata simplicia vel subramosa, parenchymatica 
 hologonimica, primum viridis, deindc purpurascens ; ccllulaj 
 cartilaginece, crisp*, interdum didymai ; spermata nunc in 
 trabeculis, nunc lateralia, globosa." 
 
 1. Zygogonium ericetorum Kiltz. 
 Plate XLI. Figs. I, 2. 
 Char. Filaments not unfrequcnthj hranclicd. Cells usually 
 ahout twice as long as broad, rarely uniting, hnt frequently 
 emitting elongated and irregidar processes, icMcli are usually 
 to he regarded as rudimentary ramuli. Endochrome oc- 
 casionally becoming effused, generally from one cell into 
 an adjoining one in the same filament, but sometimes that 
 from both cells passes into a space formed betioeen the tico 
 utricles. 
 C. ericetorum Harv. in Hook. Brit. Flora, also in Manual, 
 p. 125. ; E. Bot. t. 1553. ; Grev. Crypt, t. 261. f. 1. 
 
 Tt has elsewhere been stated that I had been induced, 
 from the detection of ramuli on some of the filaments, to 
 consider Conferva ericetorum as referrible to the branched 
 Confervas. It would appear, however, on closer examination, 
 that while it certainly, by the not unfrequent occurrence of 
 ramuli, exhibits a degree of relation to those species, yet that 
 its affinities Avith the conjugating tribe are sufficiently strong 
 
ZYGOGONIUM. 175 
 
 to make it apparent that its proper station is with these, and 
 not with the branched species. 
 
 When a communication is abont to be set up between two 
 cells in the same filament, the opposed extremities of those 
 cells are first seen to become slightly inflated, to point some- 
 what and then burst, effusing their contents sometimes into 
 a space which is formed gradually between the two cells, 
 but at others the endochromc of one cell passes directly 
 into the cavity of the other. 
 
 All the cells in a filament do not usually communicate 
 with each other at the same timis, but at distant intervals ; 
 and around those cells between which a communication is 
 about to become established, the investing membrane is ob- 
 served to be thickened considerably, pointing out to the 
 observer those cells which either have, or are about to take 
 on, the characters of reproduction. 
 
 At one time I tliought that the branches which I have so 
 often met with Averc spurious, and might have been formed 
 in the same manner as they sometimes are in il7. genujlcxay 
 &c., viz. by the union of the extremities of certain filaments 
 at right angles Avith the cells of other filaments ; but this 
 idea was dispelled by observing, that in the specimens in 
 wdiich the branches occurred most abundantly, no union of 
 cells in the regular Avay was to be met with. 
 
 The colour no less than the condition of the endochrome 
 varies considerably in this species. In some specimens the 
 filaments are of a bright green, in which case they ha^e 
 always been found immersed in Avater ; Avhile in others, and 
 more frequently, they are purple ; of which colour they in- 
 variably are Avhcn found spreading over swampy heatlis. 
 Specimens of a beautiful green colour Avere recently sent me 
 by ]\Ir. Jenner and ]\Ir. Ealfs, and these, for some time, 
 puzzled me exceedingly. 
 
 I have no liesitation in referring to this species the C. pur- 
 purascens of Carmichael, and C. alpina Bory Avhich is but an 
 aquatic condition of the plant, and strongly suspect that Conf. 
 turtuosa Dillw. (the Zygnema littoreum Lyngb., and C. per-' 
 rcptans Carm.) might be referred to it likcAA'ise. 
 
176 CONJUGATEiE. 
 
 15. STAUROCARPUS. 
 
 Char. Sporangium either square or cruciform, and lodged in 
 the transverse tubes. 
 Derivation. From aravpos, a cross, and Kapiros, fruit. 
 
 " Certain square or cruciform species of conjugating Con- 
 ferva were doubtfully associated by Agardh with the genus 
 Mougeotia ; these species I learned long since had been sepa- 
 rated from it by Mr. Shuttleworth under the appropriate 
 generic appellation of Staurocarpus. Mr. Shuttleworth how- 
 ever did not, so far as I can learn, publish his opinion of the 
 propriety of establishing for these curiously formed species a 
 distinct genus, contenting himself with communicating his 
 views to some of his correspondents, of whom I may name 
 the following as being conversant with those views : — Mr. 
 Borrer, the Rev. M. J. Berkeley, and Mr. Ealfs. Within 
 these few days I have been informed by Llr. Berkeley that 
 Kiitzing has proposed this genus under the term of Stauro- 
 spermum in a sketch of" a work on the Algce, inserted in the 
 first number of the new series of " Linna^a." No account of 
 the genus is given by Kiitzing, but merely the name and an 
 enumeration of species belonging to it. Mr. Shuttleworth's 
 appellation I conceive to be much more appropriate and ac- 
 curate than that of Kiitzing, and have therefore ventured to 
 retain it ; for the word Staurocarjms applies to the fructifica- 
 tion generally, which is either square or cruciform, while 
 Staurosj^ervmm appears to me to specify the reproductive 
 granules or zoospores themselves with Avhich each sporangium 
 is filled, and which are more or less of a circular form." — 
 Hassall, in Annals of Nat. Hist. 
 
 That Agardh entertained a very strong suspicion that the 
 square-fruited species ought to be separated from the genus 
 Mougeotia, will be apparent from the following observa- 
 tions : — 
 
 " Ceterte species quoad fructum non satis coguitfe, et 
 postea forsan separaudje, hue tantum ob habitum retentte." 
 
 The genus Staurocarpus differs from Mougeotia in the facts 
 of the transference of endochrome and formation of sporangia, 
 
STAUROCARPUS. 177 
 
 while from the genus Mcsocarpus, hereafter to be described, 
 it is separated by tlie form of the sporangium. 
 
 But one species of this genus is described by British writers. 
 In a recent number of the " Annals " two others were added, 
 and I have now tlie pleasure of describing three other species. 
 
 1. Staurocarpus glutinosus Ilass. 
 Plate XLVII. Fig. 1. 
 Char. Filaments of considerable diameter, Imjhhj mucous, 
 bluish green. Cells six or seven times as long as broad, 
 those being the longest which have conjugated. Sporidium 
 quadrangular, formed entirely by the transverse tubes. 
 Sporangia, when perfect, someivhat oval. 
 Mougeotia glutinosa, Hassall, in Annals of Nat. Hist. vol. 
 
 xxii. pi. 7. fig. 1. 
 Hab. Hertford Heath : A. H. H. 
 
 This is a very distinct and fine species, occurring abundantly 
 in boggy pools on Hertford Heath. Not unfrequently a 
 number of contiguous pairs of cells unite, forming arched 
 loops or links, separated from each other by the square 
 ovarium, which is the chief characteristic of the species. 
 
 2. Staurocarpus ccerulescens Ilass. 
 Plate XLVII. Fig. 2. 
 
 Char. Filaments of less diameter than those of Staurocarpus 
 glutinosus. Cells ustially eight or ten times as long as 
 broad. Endochrome, xchcn recent, ccerulescent ; when dried, 
 of a purple hue. Sporangia c?'z<c?/bn??, large, and filled 
 with zoospores of a greenish colour. 
 Staurocarpus capucinus Hassall, in Annals of Nat. Hist. 
 
 vol. xii. p. 184. 
 Hab. Henfield : Mr. Borrer. Tunbridgc "Wells : Mr. 
 Jenner. Penzance : Mr. Ralfs. High Beech, Essex ; 
 A. H. H. 
 
 N 
 
178 CONJUGATED. 
 
 The colour of the filaments in this, as in other species, 
 would appear to be subject to considerable variety ; in their 
 youngest condition, the filaments are stated to be cocrulescent ; 
 in their more advanced state, they are purple, and invariably 
 so Avhen dried, exhibiting on paper, which they often stain, 
 some degree of gloss. 
 
 The Leda capucina of Bory, Monrjeotia capucina of Agardh, 
 is probably identical with this species. 
 
 3. Staurocaepus quadratus Hass. 
 
 Plate XLVIIL Fig. 1. 
 
 Char. Filaments of less diameter than those of the preceding 
 species, bluish green. Sporangia quadrangidar. 
 Mougeotia quadrangidata Hassall, in Annals of Nat. Hist. 
 
 vol. xii. p. 185. pi. vii. fig. 3. 
 Hab. Cheshunt, and various places in the neighbourhood : 
 A. H. H. Ashdown Forest, and on Crawley Down, near 
 Turner's I\Iill : Mr. Jemier. 
 There is no difficulty in distinguishing this from all other 
 species hitherto recorded. 
 
 4. Staurocaepus virescens Hass. 
 
 Plate XL VIII. Fig. 2. 
 
 Char. Filaments smaller than those of St. quadratus, 
 
 usually of a grass green colour. Cells before conjugation 
 
 about eight or ten times as long as broad, but after that 
 
 period becoming nmch longer. Sporangia cruciform. 
 
 Staurocarpus affinis Hassall, in Annals of Nat. Hist. 
 
 vol. xii. p. 185. pi. vii. fig. 4. 
 Hab. Pool near Koyden, Essex : A. H. H. 
 
 This species comes very near to St, quadratus, from which 
 it is distinguished by its somewhat finer filaments, and cru- 
 ciform sporangium, the sporangia in St. quadratus being 
 square. 
 
STAUROCARPUS. 179 
 
 5. SXAUROCARrUS GRACILIS Hass. 
 
 Plate XLIX. Fig. 1. 
 
 Char. Filaments more slender than those of St. virescens, and 
 usually of a green colour. Cells many times longer than 
 broad. Sporangia cruciform. 
 
 St. gracilis Hassall, in Annals of Nat. Hist. vol. xii. pi. vii. 
 fig. 5. 
 
 Hah. Penzance : Mr. RaJfs. Waterdown Forest, Broad- 
 water Forest, Fisher's Castle, Crowborough Warren : 
 Mr. Jenner. High Beecb, Hertford Heath, "Wormley, 
 West End, and Wanstead Flats, Essex : A. II. II. 
 
 This is an abundant species, and very distinct from any of 
 the others. It was found by Mr. Ealfs, Mr. Jenner, and 
 myself, within a few daj^s of each other. 
 
 6. Staurocarpus gracillimus Ilass. 
 
 Plate XLIX. Fig. 2. 
 
 Char. Filaments more slender than those of St. gracilis, and 
 usually of a green colour. Cells very many times as long 
 as broad. Sporangia cruciform, arid about one half the size 
 of those of St. virescens. 
 
 St. gracillimus Hassall, in Annals of Nat. Hist. vol. xii. 
 p. 185. pL 7. fig. 6. 
 
 Hah. Hertford Heath and High Beech : A. H. H. Rack- 
 ham Bogs, Parham Park, near Storrington, and Ash- 
 down Forests : Mr. Jenner. 
 
 This species I have myself met Avith several times, but did 
 not at first recognize its distinctness, of which, however, I 
 now entertain no doubt : and it was only on the receipt of a 
 beautiful sketch from IMr. Jenner, accompanied by remarks, 
 that I examined thoroughly into the matter, and satisfied 
 myself of its entire distinctness. 
 
 N 2 
 
180 
 
 Fam. IX. CYSTOSPERMEiE. 
 
 Char. Filaments simple, subulate, non-conjugating. Cells at 
 first equal, subsequently here and there inflated or vesicular. 
 Sporangia formed by the union and condensation of the 
 endochrome of tioo contiguous cells of the same filament. 
 
 The impression •whicli I first entertained respecting the Con- 
 fervcB contained in this family was, that it would be sufficient 
 to regard them as constituting a new genus, referrible to the 
 ConjugatecB already described : subsequent reflection and exa- 
 mination have, however, convinced me that they should hold a 
 higher than a generic rank, and that the characters presented 
 by them are sufiiciently distinctive to entitle them to the rank 
 of a separate family. 
 
 Their filaments are simple, slightly subulate, owing to 
 the cells growing laterally, or in diameter as well as in longi- 
 tude, usually attached, do not conjugate, are articulated or 
 jointed, and terminate in lanceolate extremities: in their young 
 condition the cells are uninflated ; subsequently, however, cer- 
 tain ones swelled up, this inflation being occasioned by the 
 transference into them of the contents of one of the adjoining- 
 cells, and in these inflated cells, ultimately are formed, large 
 oval or circular bodies, similar to those of the Conjugatcce, both 
 in appearance and nature, and which therefore I in like manner 
 denominate sporangia. 
 
 In addition to these essential characters of this family, the 
 CystospermecB are distinguished by other, though less obvious, 
 not less important characteristics. The filaments are of a 
 firmer texture than those of most other Conferva, they possess 
 comparatively but little flexibility, are not mucous, and con- 
 sequently do not exhibit that glossy appearance presented 
 by so many Conferva when removed from the Avater, and 
 which they retain when dried uj3on paper ; in all which par- 
 ticulars they stand in marked opposition to that numerous and 
 
CYSTOSPERME^. 1 8 1 
 
 Important division of the freshwater Conferva, the CojijugatecE, 
 in the species of which the filaments are flexible, mucous, 
 and shining in the lilghest degree: In tliem, too, the fila- 
 ments never taper, but are always exactly cylindiical. [More- 
 over, the articulations differ in the two groups : in the Ojsto- 
 spcrmeoi they are strongly marked, and when dried, become 
 contracted and dark, while in the Conjufjatccs they are faintly 
 indicated ; and in dried specimens are often Avith difficulty 
 discoverable. 
 
 Such are the leading features of this interesting division 
 of the Confervas, and on a careful examination and estima- 
 tion of the many points of difference here enumerated be- 
 tween them and. the Conjugatece, the tribe to which they most 
 closely approximate, there can be no doubt, I apprehend, 
 of the propriety of retaining them in a separate family. 
 
 The differences are too great to admit of their holding 
 merely a generic rank. The naturalness of the different 
 genera forming the preceding family may be readily per- 
 ceived, these passing through certain species, the one into 
 the other ; and all being allied by certain resemblances : 
 but how wide is the interval between any of these and the 
 group of Cystospermeoi ! 
 
 The sporangia In the difterent species of Ci/stospermecs arc 
 produced in the same manner as in the non-conjugating 
 Zygnemata; that is, by the concentration of the contents 
 of two adjacent cells in the same filament, this being neces- 
 sarily always accompanied by the Inflation of the receiving 
 cell, and the giving cell being constantly placed In com- 
 munication with the narrow end of the ovate Inflated cell. 
 
 In all the ConjugatecR the endochrome Is seen to pass through, 
 tubes of connection between the cells, whether in difterent 
 or In the same filaments : In these, however, no such passages 
 exist, the contents of the cells escaping apparently through 
 a rent occasioned by some agency in their extremities. The 
 notice of this particular furnishes an additional distinctive 
 character between the two groups : but others still remain, 
 two of which may next be noticed. 
 
 The first of these relates to the presence of a peculiar and 
 N 3 
 
182 CYSTOSPERME.E. 
 
 regular annulatlon of the enveloping membrane of the cells, 
 which would appear at a certain epoch to be intimately- 
 adherent to the tissue of the cells themselves. 
 
 " The genus of freshwater Conferva which I have deno- 
 minated in a previous article Vesiculifcra^ , in addition to the 
 characters indicated in the definition of it given therein, such 
 as the attachment, attenuation and slight mucosity of the 
 filaments of the species composing it, as well as the formation 
 of true spores by the intermingling and union of the contents 
 of two cells in the same filament, is particularly distinguished 
 by the presence of a peculiar and regular annulatlon of the 
 enveloping membrane of the cells, which would appear at a 
 certain epoch to be Intimately adherent to the tissue of 
 the cells themselves." (PI. xvii. figs. 7, 8.) 
 
 " This annular disposition of the sheath of the cells does not 
 occupy its whole extent, but corresponds only to certain cells 
 and determinate portions of those cells ; the cells around 
 which it is disposed being those in which the spores are 
 destined to be formed, and the portion of these which it in- 
 vests being the extremities through which no endochrome 
 passes from the contiguous cells for the formation of the true 
 spores, or rather perhaps sporangia. 
 
 " The number of annuli which correspond to each fructi- 
 ferous cell varies according to the species, and is more consi- 
 derable in the long-celled species ; it would appear however to 
 be never less than two, or more than eight or ten, to each cell. 
 
 "The use of this interesting structure is much more apparent 
 than that of the provision already noticed as belonging to one 
 section of the genus Zygnema, and admits of a most satis- 
 factory explanation, it being manifestly designed to aflfbrd an 
 outlet to the imprisoned spores, which it may be supposed to do 
 in the following way. As soon as the species has reached its 
 maturity and the spores have become perfected, the annuli, 
 Avhich are intimately united to the cells, contract, most pro- 
 bably from the arrest of growth and diminution of vitality 
 
 * This genus was first established by me in the " Annals and JNIaga- 
 zine of Natural History," vol. x. p. 385. ; it will be seen, however, that 
 the views here expressed differ in many respects from those therein stated. 
 
CYSTOSPERMEiE. 183 
 
 of the plant which occur towards the completion of the pro- 
 cess of reproduction, drawing along with tliem, and thus rup- 
 turing, the slightly clastic membrane of the cells. (PI. xvii. 
 
 " Without some such beautiful and effectual provision, it 
 will be evident, on reflection, that the spores would have to 
 remain immured within their narrow cells for an indefinite 
 length of time, even until, perhaps, their vitality had ceased 
 and the cells had become their coffins ; for occupying, as the 
 spores do, but a portion of the space of the cells, and enve- 
 loped as they are in membranes, they can themselves, of 
 course, exert no influence in producing the rupture of the 
 walls of those cells. 
 
 " In all the ConfervcB with which I am acquainted, some 
 special means are provided for the escape of the spores or 
 zoospores, their liberation never being left to the sole agency 
 of decomposition of the tissue of these plants ; thus, in the 
 majority of the branched Conferva:, and in the species of the 
 genus SplmrojAca as well as in many other Conferva, their 
 liberation is eftcctcd by the rupture of the cells in Avliich 
 they are contained, which rupture is occasioned by the deve- 
 lopement of the zoospores while still inclosed within the cells ; 
 in Conferva (JSIicrospord) ylomerata a special apertm-e exists 
 for the escape of the zoospores at the period of reproduction, 
 situated at one side of the distal extremity of each cell ; in 
 the Conjugating tribe the zoospores pass out through the 
 openings of the connecting tubes of the cells, which, when 
 reproduction has been completed, separate from each other ; 
 and lastly, in the VesiculifercB, as has been shown, a more 
 complicated provision exists for the egress of the spores and 
 zoospores. 
 
 " Of all characters whereby tlie VesicuUfcrcc may be distin- 
 guished fi'om other Confcrvce, that derived from the corruga- 
 tion of the investing sheath is joerhaps the most valualile, 
 from the circumstance not merely of its being confined to the 
 species of that genus, but from its constant presence in all 
 stages of their developement ; and not only is it interesting as 
 being indicative of a Vcsiculifera, but also as pointing out 
 
 N 4 
 
184 CYSTOSPERME^. 
 
 those cells, even in the young and but little developed Vesi- 
 culifej-a, which are destined to carry the true spores when 
 the species shall have arrived at the perfection of its life." 
 
 Meyen, by whom this interesting structure seems first to 
 have been noticed, gives the following account of its charac- 
 ters in a species which he calls Cojiferva rivularis : — 
 
 " The annular structure appears worthy of notice, which 
 the upper end of many of the joints of the Conferva repre- 
 sented exhibits. This appearance is altogether analogous to 
 the annular structure observed in the horny coat of the 
 CamjyanularicB, In those polypi also this structure appears 
 first at an advanced period of growth, as is the case with 
 the Conferva, and indeed in very different species of articu- 
 lated plants of this family. The formation commences with 
 a thickening of the membrane; the constrictions then ap- 
 pear, which are not spiral, but run in horizontal rings one 
 above the other. Sometimes it seems as if this ringed sub- 
 stance were an entirely new formation." — ISIcyen, Fjian- 
 zen-physiologie, vol. iii. p. 451. 
 
 The above is the entire of Meyen's account of this cor- 
 rugated formation, which does not in all respects accord with 
 my own observations. The structure is, amongst freshwater 
 Alga3, confined to the sj^ecies of the genus Vesiculifera. 
 
 " The purpose to which the annular disposition of the horny 
 coat, of not merely the Campamdarics but of most hydroid 
 Zoophytes, is subservient, is probably that of rendering their 
 polypidoms more flexible, and consequently less liable to 
 injury from the agitation of the restless element in which 
 they dwell." * 
 
 The second particular refers to the central cytoblast or re- 
 productive vesicle, which, in the gi'oup of Cystospermece, is 
 circular, whilst in one genus of the Conjugated?, Zygnema, it 
 is somewhat quadriform, and furnished with tubular offsets. 
 
 It is at once apparent, that the mode of reproduction just 
 indicated, does not differ essentially from that first made 
 known by Vaucher, with reference to the Conjugatece, and 
 
 * See Annals of JS^at. Hist. 
 
CYSTOSl'ERMEiE. 185 
 
 especially In respect to those most interesting species which 
 I liave described as producing true sporangia, without union 
 of the filaments. 
 
 This discovery of the identity of the mode of reproduction 
 of the two families of Conferva> hitherto treated of, leads 
 necessarily to some general, and not unimportant conclusions. 
 
 Thus, it furnishes satisfactory evidence of the intimate 
 and general connection which exists between these two 
 families, which Include such a considerable proportion of the 
 freshwater Conferva, whereby much light is thrown iipon 
 the often canvassed and much disputed subject of the ani- 
 mality of the conjugating genera, for it proves, since in. 
 reality a conjugation takes j^lace for the formation of all 
 true sporangia, that both stand upon the same footing as 
 regards their animal nature, a fact, which hitherto has never 
 been suspected, the vegetable character of the Cystospermccn 
 having long been considered as established, and that If those 
 species which exhibit the curious phenomenon of conjugation 
 are really animal, so are all the true Conferva ; thus. If these 
 should at any subsequent period be removed from the vege- 
 table kingdom to the animal, so ought, as an inevitable con- 
 sequence, all the other Confci'va which I have included In 
 the group of CystospcrmecB. 
 
 But It appears to me that, from the fact disclosed of the 
 union and concentration of the contents of tico cells in so many 
 Conferva, no argument can be deduced either In favour of 
 the sexuality or animallty of the Conferva, numerous species 
 occurring, as already observed in the Introduction, in which 
 this curious phenomenon Is wholly wanting. 
 
 For my own part, I trouble myself but little with the 
 disputes about the boundaries of the two great divisions of 
 the organised world, which forcibly remind me of the search 
 carried on by ancient philosophers, for days and 3'ears, after 
 the much-desired, but imaginary philosopher's stone, endowed 
 Avith such all-pervading Influence, or the equally fruitless in-, 
 quiry after jjcrpetual motion, or any other of tlie wild chimeras 
 to which the minds of men have from time to time been 
 given. It is my belief, that no such rigid boundary exists ; 
 
186 CYSTOSPEKME^. 
 
 for in living nature there are no abrupt unsightly chasms ; 
 all is uniformity, transition, design. 
 
 To the group CystospermecB are to be referred all the true 
 Conferva I but before admitting any si^ecies as such, it is 
 necessary that it should undergo a rigorous examination ; for 
 we find placed among the ConfervcB proper many species having 
 no relation whatever with those near to which they are placed, 
 but are referrible to some others of the genera belonging 
 to the other divisions of the Conferva already established. 
 Thus C. aljnna, C. j^urjmrescens, C. zonata, C. punctata, 
 C. ericetorum, C. mucosa, are placed by Agardh the elder 
 and Harvey amongst the Confervce properly so called. The 
 first two, nevertheless, are Conjugates, C. zonata and C. punc- 
 tata SpliaroplecB, and C. mucosa a Desmidium. 
 
 It may be thought by some, that instead of instituting a 
 new generic name, it would have been better to have reserved 
 for the species included under it the old appellation of Con- 
 ferva. To the adoption of this course, two objections pre- 
 sent themselves ; the first is, that it appears unadvisable 
 that the term Cojferva should ever be employed merely in a 
 generic sense — that a wider meaning ought to be extended 
 to the Avord — that it should be employed in the same manner 
 as the term Zoophyte, and made to embrace the filamentous 
 division of the Algce ; and the second is, that there is no 
 reason founded in right, why this term of Linnreus should 
 be perpetuated in any other way than that suggested, he, 
 and all who have hitherto employed it, having had no defi- 
 nite ideas respecting the exact nature of the productions 
 which ought to be referred to it — AlgcB widely differing in 
 essentials having constantly been placed under it. 
 
 Five of the six species of Prolifcra described by Vaucher 
 are certainly to be referred to the genus Vesiculifera, the 
 sixth C. glomerata is of an entirely difterent nature. So im- 
 perfectly and inaccurately, however, are those species de- 
 scribed and delineated, that it is impossible to identify them 
 with any degree of certainty. The following is Vaucher's 
 account of the reproduction of the genus Prolifera, Avhich, it 
 
CYSTOSrEIlMEiR. 187 
 
 will be seen, is not In all respects inaccurate, though still, 
 for the most part, very erroneous : — 
 
 " When the Prolifcrcn are ready to reproduce, cylindi'ical 
 enlargements are seen to arise in the length of the filaments, 
 which one would take for knots, if the plants Avere not arti- 
 culated or chambered. These bourrelets, at first but little 
 apparent, soon increase in size, and finally become covered 
 with a pulverulent material, Avhich is formed either by refuse 
 matter Avliich floats in the liquid, and which has been re- 
 tained within the elevations, or of a material which is secreted 
 by the ConfervcB. When this powder has remained some 
 time upon the enlarged part of the stem, a number of fila- 
 ments are seen to issue from it, which form at first little 
 rounded heads. Unfortunately this powder at the same 
 time that it seems to favour the increase of the young Con- 
 fervce baffles greatly the observer. He Is able to see but 
 little of tlie first developement of the plant, and in conse- 
 quence is not aljlc to judge, whether It Issues from the sur- 
 face of the enlargement or from the centre : whichever it 
 may be, the young filaments extend themselves round all the 
 circumference, where they form as It were a tuft of hairs. 
 Little by little their cells begin to be marked out ; soon their 
 tubes resemble in miniature those of the great Proliferce. 
 Lastly, they go and form elsewhere a new individual, like to 
 that from AvhIch they took their birth : but I acknowledge," 
 says Vaucher, " that I have not seen this separation, although 
 I have no doubt but that it really takes place." 
 
 What Vaucher regards as the young proliferous offspring, 
 are doubtless to be regarded as parasitic growths, to which tlie 
 ConfcrvcB are peculiarly liable, more especially Avhen they are 
 confined for a length of time in small vessels of Avater. 
 
 Tavo other species of this group have been referred by 
 Meyen to a genus Hempelio, which he instituted for tlicm, a 
 genus even more erroneously defined than that of Prolifera, 
 already noticed. 
 
 " IIeimpelja. — Thallus simplex, mcmbranaceus, scptatus, 
 a3qualis vel Ini\;qualis. Fructus tcrailnalls est, capsula sub- 
 
188 CYSTOSPERME^. 
 
 pyrlformis, aplce regulariter vel irregularlter deliiscens, et 
 sporas emittens. Spora3 globosa?^ hyaliua3, massa grumoso- 
 submucilaginosa infarctas, utrlculos implentes. 
 
 ''H. mirabilis. — Filis inequalibus virldibus brevibus, septis 
 semi-pellucidls ; sporis e capsulls emissis ad fascicules con- 
 junctis ; utricuHs cylindricls diametro dupli-triplo longioribus, 
 hinc inde ad globules tumescentibus, qui, secreti ab aliis 
 utrlculis, ut animalcula infusoria, se moYCnt et, rumpeutes 
 eorum racmbrana, sporas emittunt." 
 
 Tor the following translation of Meyen's remarks upon 
 the above species I am indebted to Mr. Kippist, to whom I 
 may take this opportunity of rendering my best thanks for 
 the kindness and readiness with which that gentleman has 
 always undertaken whatever could facilitate the progress of 
 this work : — 
 
 " This plant is found in a water-tank of one of the warmest 
 houses of the botanic garden at Bonn. I first observed it 
 in the beginning of January of the present year (1827). It 
 w^as at that time already in fruit, and during a period of 
 three and a half months, during which I have observed it, it 
 has continued quite in the same condition in which I at first 
 found it. 
 
 " It is a constant character of this Conferva, that the fruit 
 capsule appears at that end of the filament by which it is at- 
 tached to the side wall of the Avater-tank, and from the great 
 mass of spores scattered by the capsule, all the ConfervcB 
 which spring up at the same spot grow together into such a 
 heap that their basis appears of an almost uniform black, 
 from which the Confervcz project In a radiating manner. I 
 have not yet succeeded in determining whether the threads 
 have first attached themselves to the wall of the tank, after 
 the formation of the capsule, or whether the last joint, by 
 which they, as it were, take root on the wall, may have 
 gradually assumed the form of a pear-shaped capsule, with 
 an extended neck. Even if in this latter case the explanation 
 of the structure of the capsule should present further diffi- 
 culties, I might still be able to explain them. I have but 
 very seldom been able to observe the streaming out from the 
 
CYSTOSPEEME^:. 189 
 
 capsule of the masses of spores, which were surrounded by 
 a bright green granular mucilaginous mass, and thus were 
 held together in a ball. I have never been able to observe, 
 in the interior of this mass any peculiar motion of the 
 spores, yet I have seen that during the discharge {Ausstro^ 
 men) several seeds separated themselves from tlie principal 
 mass, and then exhibited a high degree of voluntary motion, 
 which often lasted a long time, and which still belonged to 
 them when tliey had distinctly increased in length, appa- 
 rently in order to produce new individuals : this occurrence I 
 have not actually been able to observe in this species, but I 
 hope that during this summer it will not escape me. 
 
 " The above-mentioned capsule is exhibited in very different 
 forms In the accompanying tables; it ordinarily presents a pear- 
 shaped figure^ with a more or less elongated neck, which fi'e- 
 quently expands into the form of a funnel; the breadth of the 
 capsule is greater at the base than that of the next joint. The 
 gradual developement of this organ, which I have not been able 
 to observe here, will be given with the following species. It 
 is however to be observed that the capsule, after the discharge 
 of the spores, separates from the filament, and then presents 
 the form which is to be seen in figures 8 and 9. 
 
 " The filaments are dissimilar, and, with advancing age, 
 the dissimilarity increases, so that, at length, the elliiotical 
 form of an utriculus passes Into a perfectly spherical one. 
 I had the good fortune to observe how such a spherical 
 utriculus separated itself, under my eyes, from the other 
 tubes {Schlduchen), and, existing only for itself, moved, I 
 might almost say voluntarily, with incredible swiftness in all 
 directions. Figure 11. a and b show these detaclied spherical 
 utrlculi; and, Avhilst observing them, I succeeded, by blowing 
 on the object-bearer, in hastening this separation, and then 
 observed the free motion of the separated tube. With regard 
 to the structure of this organ, it is to be observed, that it is 
 usually as simple as that of the ordinary utriculus, Avhilst the 
 spherical cell is closely filled with masses of spores. In one 
 part, hoAvever, of the circumference of the sphere may be seen, 
 upon close examination, a transparent portion, like an affixed 
 
190 CYSTOSPERMEiE. 
 
 larger section of a smaller sphere, which, during motion, is 
 always directed forwards, while the entire sphere continually 
 revolves on its longer axis, and this with a wonderful rapidity. 
 At length I observed the fine skin of the organ to burst, and 
 with the discharge of the motionless spores, followed the death 
 of the animal life (der Tod des animalischen Lehens) of this 
 organ, and the plant appeared. It must also be observed, 
 that the mass of spores, which is discharged from this sphere, 
 is much more highly developed than that which escapes from 
 the capsule, since in the former they are little more than 
 vesicles, and scarcely present any thing of the grumous shiny 
 mass, which in the latter is very evident. 
 
 "In figs. 12. and 13. are displayed similar organs of irre- 
 gular form, whose origin It is very difficult to explain. If I 
 had not observed "the springing up of this organ, as well as 
 its propagation {Fortpjianzung), of which I shall speak here- 
 after, one might sujjpose it to represent the seeds, which here 
 appear to be a little more extended, and seated on the parent 
 plant, to be about to shoot out into young Conferva. This 
 idea is, however, entirelj^ false, since such a mode of growth 
 occurs only in the inarticulate Conferva, and therefore in 
 Vaucheria. In conclusion, I must be allowed to assert that 
 this species has hitherto never been observed, since the dark- 
 green colour, the shortness of the filaments, and their lying 
 one upon another, are very striking characters ; yet we no- 
 where find them given." — Meyen, Kritische Beitrdge zum 
 Studium der Susszcasser-Algen Flora, No. 45., December, 
 1827. 
 
 INIeyen's second example, H. polgmorpha, seems to include 
 more than one species belonging to different genera. 
 
 The genus Hempelia is false both in fact and philosophy. 
 The capsule, upon which Meyen lays so much stress, is 
 nothing more than the first developed cell of the Conferva, or 
 transformed zoospore, and has nothing vvhatever to do with 
 the reproduction of the species. To imagine that it has, is 
 in the highest degree unphilosophical, for it is to attribute 
 that function, which is indicative of the perfection of the life 
 of an organic being, and whicli is the last for it to assume, to 
 
CYSTOSPERME7R. 191 
 
 the part of the plant first formed ; it Is to invert in fiict the 
 natural order of things 
 
 In the third volume of the "Memoircs du Museum," 1817, 
 there is a paper by M. Leon le Clerk, on the genus Pro- 
 lifera. In this paper Vaucher's error In refercnee to growth 
 of the species by shoots is pointed out, and the formation 
 of circular bodies or sporangia noticed. M. Leon le Clerk was 
 not satisfied, however, that these bodies were formed by the 
 union of the endochrome of two cells, as they doubtless usually 
 are, "But it avIU be asked," he remarks, "what cause 
 determines the formation of the green matter Into the globule 
 which we have described. To this question Nve frankly avow 
 our ignorance. We can only give the assurance that this for- 
 mation takes place without any kind of union with another 
 filament, as we had at first suspected from analogy to the 
 ConjugatecB. Perhaps, pre-occupied by the same analogy, one 
 might be led to suppose that two neighbouring divisions of 
 the same filament united their green matter to form the re- 
 productive globule. This supposition vanishes however upon 
 the slightest examination. The two divisions indeed bor- 
 dering on that which contains the grain present often the 
 green matter In its integrity, and If there be need for a fact 
 still more decisive, it has occurred to us often to meet with 
 not only two contiguous inflated cells, but three or four adjacent 
 cells all equally In fructification." 
 
 These two facts, mentioned by M. Leon le Clerk, do not 
 at all disprove the general rule, that the globules or sporangia 
 are formed by the union and condensation of the endochrome 
 of two cells. The correctness of the first statement Is very 
 questionable; It has never occurred to me to notice endo- 
 chrome In the cells on both sides of the sporangium, and I 
 am certain that where this body Is perfectly formed the 
 greater portion of the green matter of the cells on one side or 
 other of it will invariably be found to have quitted that cell. 
 
 "With regard to the second particular, viz. the occurrence 
 of more than one sporangium in contiguous cells, this I think 
 can scarcely be regarded as an exception to the rule, at least 
 It admits of explanation. The occurrence of two contiguous 
 
1 92 CYSTOSPERME^. 
 
 inflcated cells occupied with sporangia or globules, is quite 
 consistent with the idea of these bodies being formed by the 
 contents of two cells, since each may be in contact on either 
 side with au inflated cell. In the very rare instances in which 
 three or four contiguous cells occur, I have never noticed 
 a perfect globule in each of these, and even if such ever exist, 
 each globule yet might be formed not indeed of the entire 
 contents of two cells, but still of a portion of the green matter 
 of two. 
 
 M. Leon le Clerk thus defines the genus Prolifera. 
 ** Filamentis loculatis simplicibus, materia viridi granulis 
 fulgidis aspersa totaliter repletis. Singulo loculo, fructifica- 
 tionis tempore, projyriis viribus in glohulam suam efformante. 
 Isto globulo intense viridi ex loculo demisso novam plantam 
 emittente." 
 
 This definition of M. Leon le Clerk is exceedingly faulty. 
 It is not in each cell that the round globule is formed, but only 
 in occasional cells, or at most in alternate cells; and the asser- 
 tion that this globule really gives origin to a new plant, is 
 by no means established. Even INI. J. Decaisne, who has 
 separated the Conjugates from the Alg(R zoospore of Agardli, 
 does not state that he has Avitnessed their developement, but 
 Infers this from the fact that the filaments of the Conjugated;, 
 whether young or old, in the same species, invariably present 
 the same diameter, and thus, as he supposed, could not pro- 
 ceed from organs so minute as the zoospores. 
 
 M. Decaisne combats the idea of the disintegration of the 
 sporangia of the Conjugates and VesiculifercB into zoospores, by 
 the fact that their contents are at all times fluid. This argu- 
 ment is, however, by no means conclusive, the contents of 
 the cells of the Vesiculiferce, &c., are also generally fluid ; but 
 this fluid, when the proper period arrives, becomes fashioned 
 into distinct organs or zoospores, and the same may be the 
 case with the contents of the spores of the Zygnemata, as 
 asserted by Agardh. 
 
 M. Decaisne also repudiates the idea of a double mode of 
 reproduction ; the spores he regards as the true and only re- 
 productive bodies of those AlgcB Vvdiich possess them ; but it 
 
CYSTOSPERMEiE. 193 
 
 is perfectly certain tlie usual and most frequent method of 
 reproduction of the VesiculifcrcB is by means of zoospores, and 
 this fact, of which I have so perfectly assured myself, leads 
 to adoption of one of the following views — either that the 
 large, oval, or spherical bodies of the AI(/cb, comprised in M. 
 Decaisne's class of zoosjiores, are not in any way connected 
 with reproduction ; a view which can scarcely be regarded as 
 probable, and opposed to that entertained by M. Decaisne 
 himself; or that they as well as the zoospores do perpetuate 
 the species ; in favour of which view the evidence can scarcely 
 be pronounced sufficient to remove all doubt of its correctness. 
 
 Link has endeavoured to establish this genus under the 
 name of (Edogonhim, which has been adopted by Klitzing, 
 Avho thus Imperfectly characterises it. 
 
 " Trichoma simplex, membranaceum, flaccidum. Cellulte 
 coelogonimica3, gonidia minutissima mobilia continentes. Sper- 
 matla solitaria globosa fusca, epispermo dupllci hyalino cincta, 
 cellulis inclusa." 
 
 In this description no allusion is made to the mode of 
 formation of the sporangia, and none to the ringed apparatus 
 with which each fruit-bearing cell is provided. 
 
 Several other generic terms have been applied to certain 
 species of the genus Vesiculifcra, such as Tircsias, Cachmis, 
 Zoocarpa *, &c. but all of them, so far as I can learn, are 
 
 * Respecting the genera CEdogonium, Tb'csias, and Zoocarpa, I have 
 obtained the following information : — In the " Dictionnaire Classique," 
 vol. xii. p. 78., Bory thus remarks on the genus QSdogonium. " The genus 
 proposed by Link under this name appears to be the same as that which 
 Vaucher named Prolifera, for which we have adopted the name of 
 VaucJieria. In the remarks on VaucJieria, Bory states that it was wrong 
 of De Candolle to change the name of Ectosperma, which he proposes to 
 restore, and to confer the name of Vaucher on the genus Prolifera, that 
 appellation being founded in error : and Guilleman in the 16th volume, 
 p. 268., of the same work, under the head of Tiresias, observes — ' Our 
 co-labourer, Bory de St. Vincent, has established and described a new- 
 genus of the family oi Arthrodca: and of the ti'ibe of Zooca?-pc<v, in which 
 he indicates as the principal species the Conferva hipartita of Dillwyn 
 (a Tyndaridea ?). The characters of this genus have been explained in 
 this Dictionary, vol. i. p. 597 — 1822.' Since that time the genus has been 
 adopted by Fries, who has placed it amongst his Hydrophytes or Alga:; 
 O 
 
194 CYSTOSPEKMEiE. 
 
 founded upon a partial, imperfect, and often inaccurate know- 
 ledge, and therefore not admissible. If any of the older 
 terms should be retained for the genus Vesiculifera, it should 
 be by right of priority, — Conferva, for this genus hitherto 
 has been made to embrace various species of Vesiculifera, as 
 well as certainly a heterogeneous mass of other productions ; 
 but it seems to me that this genus ought to be abolished 
 altogether, and that the term Conferva should be used in a 
 more extended sense, and applied generally to any species of 
 the coufervoid Alga, in the same manner as the word zoo- 
 phyte is now used. Kiitzing, in his " Phycologia Generalis," 
 confines the genus Conferva to certain species of Spharoplea, 
 and to the marine species of Confervce, with simple filaments, 
 such as Conf area and its allies. Next to Conferva, Prolifera 
 
 and Tvho olaserves that tlie Zooearpea of Nees of Esenbeck, " Nov. Act. 
 Nat. Cur." an. 1813, p. 517., Is the same genus. The same author 
 thinks that the greater part of the Prolifera of Vaucher, also the CEdo- 
 gonium of Link, ought to constitute part of the genus Tiresias. Of 
 Tiresias, Bory gives the following description : ' Filaments cylindrical, 
 the interior tube filled with green colouring matter, in Avhich are de- 
 veloped hyaline corpuscles which separate from the filaments. This 
 colouring matter ends by becoming agglomerated in each cell into a 
 sphere or zoocarpe, of appearance similar to the gemmfe of the Con- 
 jugatce, and inert up to the moment when ruptiiring the cell by its 
 developement, and, putting itself in contact with the surrounding fluid, 
 it commences to move itself in dilTerent directions, and finishes Jjy swim- 
 ming freely about, leaving all broken and transparent as water the tube 
 which produced it.' The Conferva hipartita of Dillwyn is certainly a 
 species of Tiresias, in the vegetable condition of which the Cercaria 
 podura and viridis of Mliller are the Zoocarpes, which we have seen 
 after a certain period of liberty fix themselves by their divided extremities 
 upon the remains of vegetables, or even upon the filaments of other 
 Tiresias, and elongate themselves into a confervoid vegetable. This 
 state of elongation has been well seen and figured by Le Clerc, in his 
 excellent memoir on the ProlifercB of Vaucher, as well as by Dillwyn 
 upon his Conferva genvflexa. It is surprising that these skilful naturalists 
 had not detected the metamorphoses of the Enchalis Into that which they 
 call Confervce." 
 
 Both Bory and M. Leon le Clerc are in error in supposing that they 
 had witnessed the developement of the large oval or spherical bodies 
 formed by the concentration of the endochrome of two cells : what the 
 latter represents are undoubtedly the zoospores in different stages of 
 growth. 
 
VESICULIFERA. 195 
 
 lias the greatest claim to be retained: a name, however, 
 founded in error. 
 
 16. VESICULIFERA. 
 Char. Same as those of the family. 
 Derivation. From Vcsiada, a vesicle, and jfero, to bear. 
 
 1. Vesiculifera princeps Ilass. 
 
 Char. Filaments of the same diameter as those of V. cajnl- 
 laris. Cells about once and a half as long as broad. 
 Sporangia circidar, ■producing but a very slight inflation of 
 the fructiferous cell. 
 
 Isogonium capillare Kiitz. Phyc. Gener. 255. V. priiiceps 
 Hassall, in Annals, vol. x. j). 388. 
 
 Hab. Cheshunt: A.H.H. 
 
 This species I described in the Annals of Natural History, 
 vol. X. p. 388., under the name of F. princeps; but not meeting 
 with it a second time, and fearing that it was not really dis- 
 tinct, I referred it to V. capillaris. I am now, however, 
 induced again to regard it as a distinct species, from the cir- 
 cumstance of its being described as such by Kiitzing under 
 the name of Isogonium capillare, a subgeneric ajipellation, be- 
 stowed upon it on account of the sporangia not producing any 
 considerable inflation of the fruit-bearing cells, — a cii'cum- 
 stance which scarcely called for such a distinction. The 
 figure given by Kiitzing accords closely wdth one made by 
 myself of the species long ago, and which I regret I have not 
 here introduced. The non or slight inflation of the cells will 
 distinguish it from all other described species. 
 
 2. Vesiculifera capillaris Ilass. 
 
 Plate L. Figs. 1, 2. 
 
 Char. Filaments of considerable diameter. Cells varying in 
 length from nearly ticice to almost four times their dia- 
 meter. Sporangia large, circular, contained in distinct 
 inflations of the cells of an evidently ovate form. 
 
196 CYSTOSPERMEiE. 
 
 Vesiculifera capillaris LinnECUS? Hassall, in Annals of 
 Nat. Hist., vol. x. p. 389. V. princeps Hassall, in 
 loc. cit. Prolifera composita Vaucher, Hist, des Conf., 
 p. 133. pi. 14. fig. 5. 
 
 Hah. Ponds near Netting Hill; Cheshunt, and its 
 vicinity : A. H. IL 
 
 A'NTietlier the Vesiculifera, wliicli is here regarded as the 
 Conferva capillaris of Linnasus, be that species or not, there 
 can be no question but that it is the same plant as that con- 
 sidered as such by Agardh, as I have been able to ascertain 
 by the examination of an authentic specimen of Agardh's 
 C. capillaris var. B. alternata, contained in the Herbarium 
 of Dr. Greville. None of those who have noticed tliis 
 species were at all acquainted, however, with the true re- 
 production. 
 
 3. Vesiculifera condensata Hass. 
 
 Char. Filaments of more considerable diameter than those 
 of V. capillaris. Cells not so long as broad. 
 Vesiculifera condensata Hassall, in Annals of Nat. Hist., 
 vol. X. p. 388. 
 
 Not having again met with this species since it was de- 
 scribed in the Annals, and never having seen it in a state of 
 reproduction, I am led to think that possibly it may be but 
 a variety of C. capillaris ; than which, however, the filaments 
 are thicker, and the cells much shorter. It was found ad- 
 herent to a wall reached by the tide in the Thames near 
 Barnes. 
 
 4. Vesiculifera crassa Hass. 
 
 Plate LI. Fig. 1. 
 
 Char. Filaments y?<% equal in diameter to those of V. capil- 
 laris. Cells usually Jive times as long as broad. Spo- 
 rangia oval, generally solitary, but soinetimes binary, con- 
 tained in cells of a slightly oval form, the length of lohich 
 about txoice exceeds the diameter. 
 
VESICULIFERA. 197 
 
 Vesiculifera crassa Hassall, in Annals of Nat. Hist., vol. x. 
 
 p. 389. 
 Hab. In a pond at Wood Green, near Bury Green, vicinity 
 
 ofCheshunt: A. H. H. 
 
 The only species near to which this approaches is V. 
 Lands!) or oughi ; than which the filaments are much thicker 
 and the inflated cells shorter and less marked. 
 
 Having met with it now several times, I have not a doubt 
 of its being distinct from V. Landshoroiighi. 
 
 5. Vesiculifera Landsboroughi Ilass. 
 
 Plate LI. Fig. 2. 
 
 Char. Filaments of co7isiderahle diameter^ hut scarcely so 
 large as those of the preceding species. Cells at the jjeriod 
 of fructification, about five or six times as long as broad. 
 Sporangia oval, contained in inflated cells of an elongated 
 but not rcgidarhj oval form, these occurring usually singly 
 at i7itervals of three or four cells, but sometimes two are 
 juxta-jjosed. 
 Vesiculifera Landsboroughi Hassall, in Annals of Nat. Hist., 
 vol. X. p. 389. Prolifera rivularis M. Leon le Clerc, 
 Mem. du Mus. t. 25. 
 Hab. Vicinity of Cheshunt, very rare : A. H. H. In an 
 old coal-pit near Stevenston, Ayrshire : Rev. D. Lands- 
 borough. Penzance : Mr. Ralfs. 
 
 I have much pleasure in dedicating this, one of the finest 
 species of the genus, to the Rev. David Landsborough, by 
 whom the merit of its discovery is shared equally with myself, 
 as an expression of ray warm admiration of the zeal displayed 
 by that gentleman in the cause of natural science. 
 
 I have met with this species but sparingly myself, but have 
 received excellent specimens of it in a state of reproduction 
 from INIr. Landsborough, who aptly compares the form of 
 the seed-bearing cells to that of the " soldering of lead 
 
 pipes." 
 
 o 3 
 
198 CYSTOSPERME^. 
 
 6. Vesiculifera CUVIERI Hass. 
 
 Char. Filaments more slender than those of the preceding 
 species. Cells usually seven times as long as broad. Spo- 
 rangia oval, contained in inflated cells of an ovate form. 
 Vesiculifera prolongata Hassall, in Annals of Nat. Hist., 
 
 X. 390. Prolifera Cuvieri Le Clerc, Mem. du Mus. 
 Hah. Pond near Louton, Essex, and again near Enfield : 
 A. H. H. 
 
 This species is knoAvn from V. Landshoroughi hj its finer 
 filaments, longer cells, and ovate form of the seed-bearing in- 
 flated cells. 
 
 " The inflations of Prolifera rividaris present an oval, whose 
 great diameter is never double the small. In the Prolifera 
 Cuvieri this enlargement is so much allongated that one 
 might distinguish it almost as well by the intensity of its colour 
 as by its size. In its state of greatest contraction its great 
 diameter is triple or quadruple that of the small. The same 
 proportion, but a little less marked, is observed between the 
 grains of the two Confervoi.^'' 
 
 7. Vesiculifera lacustris Hass. 
 Plate LII. Fig 1. 
 
 Char. Filanlents nearly equal in diameter to those of V. 
 Cuvieri. CeIls_/ro?« three to five times as long as broad. 
 Sporangium oval, sometimes almost quadrangular, solitary, 
 occasioning no very considerable enlargement of the cell 
 in which it lies ; empty cell next the spore also inflated. 
 Vesiculifera lacustris Hassall, in Annals of Nat. Hist., 
 
 vol X. p.390. 
 Hah. In the New River reservoir, near Cheshunt, spar- 
 ingly, and other places in the vicinity : A. H. H. 
 
 V. lacustris differs from V. Borissii principally in being al- 
 together a more robust species, and in having shorter cells. 
 
VESICULIFERA. 199 
 
 8. Vesiculifera paludosa Hass. 
 Plate LII. Fig. 3. 
 Char. Filaments of less considerable diameter than those of 
 V. lacustris. Cells usiiaUy three times as long as broad. 
 Sporangia ovaly contained in inflated cells of the same 
 form. 
 Vesiculifera paludina 9 Hassall, in Annals of Nat. Hist., 
 
 vol. X. p. 390. 
 Hab. Cliesliunt : A. H. H. Framfield Common : Mr. 
 Jenner. 
 
 This species comes nearest to V. ciliata ; but the inflated 
 cells are of a different form. I know not whether this be tlie 
 species, described by me in the " Annals " as Vesiculifera 
 paludina^ or whether that species be different from V. capillaris^ 
 not having had opportunities of making any comparative ex- 
 amination of them. 
 
 9. Vesiculifera pulchella Hass. 
 Plate L. Fig. 3. 
 
 Char. Filaments of considerable diameter. Cells usually two 
 and a half or three times as long as broad. Sporangia 
 circular^ contained in much inflated cells, xohich are at first 
 oval, then circular, and lastly someiohat hexagonal. 
 Hab. Cheshunt ; Notting Hill : A. H. H. 
 
 This is a very fine species, seeking usually rather pure 
 water ; it is of an intense and beautiful green colour. 
 
 10. Vesiculifera Ralfsii Hass. 
 
 Plate L. Fig. 8. 
 
 Char. Filaments usually rather smaller than those of V. jml- 
 chella. Cells varxjing in length from twice to four times 
 their diameter. Sporangia circular, lodged in cells of an 
 hexagonal form. 
 
 o 4 
 
200 CYSTOSPERME^. 
 
 Vesiculifera pulchella var. Hassall, in Annals of Nat. Hist., 
 
 vol. X. p. 390. 
 Hob. Chesliunt and its vicinity, especially Cbeshunt Com- 
 mon : A. H. H. Penzance : Mr. Ralfs. 
 
 Subsequent examination has confirmed the suspicion ori- 
 ginally entertained that this species, which was first sent me 
 by Mr. Ralfs, was distinct from V. pulchella : the inflated 
 cells are smaller and more hexagonal than they are in that 
 species. 
 
 11. Vesiculifera Vaucherii ^a^s. 
 
 Plate L. Fig. 4. 
 
 Char. Filaments about equal to those of V. pulchella. Cells 
 usually two and a half or three times as long as broad. 
 Sporangia circidar, lodged in cells lohich are very consider- 
 ably inflated and of an ovate form. 
 V. ventricosum Hassall MSS. Prolifera Vaucherii ? M. 
 
 Leon le Clerc, loc. cit. 
 Hab. Cheshunt: A. H. H. 
 
 This is a very distinct species, differing from V. virescens 
 in its circular si^orangia, and highly inflated cells, and from 
 V. pulchella in the ovate form of the inflations, which in 
 the latter species are slightly hexagonal. 
 
 12. Vesiculifera virescens Hass. 
 Plate L. Fig. 5. 
 
 Char. Filaments equalling in diameter those of V. pulchella. 
 Cells once and a half or twice as long as broad, fasciated. 
 Sporangia ovate, contained in cells of the same form. 
 Vesiculifera virescens Hassall, in Annals of Nat. Hist., 
 
 vol. X. p. 391. 
 Hab. Notting Hill, near London : A. H. H. 
 
 This species comes very near to the following, of which 
 possibly it may be but a variety. 
 
VESICULIFERA. 201 
 
 13. Vesiculifeea ovata Hass. 
 
 Plate L. Fig. 6. 
 
 Char. Filaments about equal to those of V. vircscens. Cells 
 three or four times as long as hroad. Sporangia ovate, 
 occasionally circular, contained in inflated cells of an 
 ovate form. 
 
 Vesiculifera ovata Hassall, in Annals of Nat. Ilist., vol. x. 
 p. 392. 
 
 Hah. Clieshunt : A. H. H. Turner's Hill and Heath- 
 field : Mr. Jenner. 
 
 This at all events is a very distinct species, if the preceding 
 one be not equally so. 
 
 14. Vesiculifeea concatenata Hass. 
 
 Plate LI. Fig. 3. 
 
 Char. Filaments thicker than those of V. ovata. Cells six 
 times as long as broad. Sporangium ovate; cell next 
 the sporangium inflated. 
 
 Vesiculifera concatenata ? Hassall, in Annals of Nat. Hist., 
 vol. X. p. 392. 
 
 Hab. Cheshunt Common and pond near Highgate: 
 A. H. H. In a pool between Hook Green and Lam- 
 berhurst, and at Peasmarsh and Henfield : Mr. Jenner. 
 
 Sometimes two or three sporangia occur contiguously to 
 each other. I am not quite sure that this is the species de- 
 scribed in the Annals by me as Vesiculifera concatenata, 
 but believe it to be so. There is not a more distinct species 
 in the genus. 
 
 15. Vesiculifera Borissii Hass. 
 
 Plate LII. Fig. 7. 
 
 Char. Filaments of nearly the same diameter as those of 
 
202 CYSTOSPERME^. 
 
 V. ovata. Cells from four to seven times as long as 
 broad. Sporangia oval, frequently of a golden colour, 
 usually solitary, hut sometimes hinary ; cells next the spo- 
 rangia inflated. 
 
 Prolifera Borissii IM. Leon le Clerc, Mem. du Museum, 
 pi. 25. fig. 6. Vesiculifera aurea Hassall, in Annals of 
 Nat. Hist., vol. x. p. 392. 
 
 Hah. Wood Green, near Buiy Green, vicinity of Ches- 
 hunt : A. H. H. 
 
 This is a very distinct species, as also a very beautiful ob- 
 ject under the microscope. There can be no doubt about the 
 synonyme of M. Leon le Clerc. 
 
 16. Yesiculifera ciliata Hass. 
 Plate LII. Fig. 2. 
 
 Char. Filaments smaller than those of V. 2mlchella, termi- 
 nated hy long colourless cilia. Cells about three times as 
 long as broad. Sporangia oval, lodged in cells of the same 
 form. 
 Hob. Cheshunt : A. H. H. 
 
 The presence of cilia on the extremities of the filaments 
 renders this a very remarkable species, and one by which it 
 may be readily recognized. There is an evident analogy 
 between the genera Vesiculifera and BulbochcBte, and through 
 V. ciliata there would aj^pear to be an easy transition from 
 the one to the other. 
 
 I?- Vesiculifera dissiliens Hass. 
 Plate L. Fig. 7. 
 
 Char. Filaments of considerable diameter. Cells scarcely so 
 long as broad. Sporangia circular, contained in inflated 
 cells of the same form, and which are usually solitary. 
 Vesiculifera dissiliens Lyngb. et Ag. 
 
VESICULIFERA. 203 
 
 Hah. Clieshunt : A. H. H. Turf Dyke, near Ardrossaii, 
 Ayrshire : Major Martin. 
 
 The aboA^e is a very beautiful species under the microscope : 
 it is to be distinguished from all others by the shortness of its 
 cells. In the Herbarium of Dr. Greville I find a S23ecimen of 
 this species, not indeed in a state of reproduction, put up by 
 M. Chauvin, and marked with doubt as Conferva dissilicns 
 Lyngb. It is certainly not the Conferva dissiliens, either of 
 Dilhvyn's work, or of " English Botany," that of the latter 
 work being probably identical with Desmidium miicosnm. 
 
 18. Vesiculifera cardiaca Hass. 
 Plate LI. Fig. 4. 
 
 Char. Filaments of much less diameter than those of V. pul- 
 chella. Cells^ue or six times as long as broad. Sporangia 
 circular, placed in much inflated cells, which may be com- 
 pared to a heart in form. 
 Vesiculifera cardiaca Hassall, in Annals of Nat. Hist., 
 
 voL X. p. 391. 
 Hah. Pond near Notting Hill : A. H. H. In a pool 
 between Hook Green and Lamberhurst : 31r. Jcnner. 
 
 This species would a^Dpear to be an uncommon one, for I 
 have only twice met with it. 
 
 19. Vesiculifera crisp a Hass. 
 Plate LII. Fig. 8. 
 
 Char. Filaments much more slender than those of V. vciitri- 
 cosum. Cells Visually three times as long as broad. 
 Sporangia circular, lodged in cells of an ovate form. 
 Vesiculifera crispa Hassall, MSS. 
 
 Hah. Cheshunt and vicinity : A. H. H. Between Wad- 
 hurst and Ticchurst, and between Ramslye Rocks and 
 Broadwater Forest : Air. Jcnner. Cannon Hill Quarry, 
 near Ardrossan, Ayrshire : Major Alartin. 
 
204 CYSTOSPERME^. 
 
 This is certainly a very distinct species, and one moreover 
 by on means uncommon. 
 
 20. Vesiculifera fasciata Hass. 
 Plate LIII. Fig. 6. 
 
 Char. Filaments of diameter about equal to that of V. crispa. 
 Cells usually three times as long as broad. Sporangia 
 
 circidar, contained in cells of the same form. 
 Vesiculifera fasciata Hassall, in Annals of Nat. Hist., vol. x. 
 
 p. 392. 
 Hob. In a pond on Nazing Common, Essex : A. H. H. 
 
 This species differs from the preceding only in the shape of 
 the seed-bearing cells, which in V. crispa are somewhat ovate, 
 while in V. fasciata they are quite circular. It is possible 
 therefore that it is but a variety of V. crispa. 
 
 21. Vesiculifera sph^rica Hass. 
 Plate LIII. Fig. 5. 
 
 Char. Filaments about equal to those of V. fasciata. Cells 
 
 usually once and a half or twice as long as broad. 
 
 Sporangia spherical, contained in enlarged cells of the 
 
 same form. 
 
 Vesiculifera sphcerica Hassall, in Annals of Nat. Hist., 
 
 vol. X. p. 392. 
 Hab. Vicinity of Cheshunt : A. H. H. 
 
 This species differs only from the preceding in having 
 much shorter cells. I believe it to be distinct, however. 
 
 22. Vesiculifera compressa Hass. 
 
 Plate LIII. Fig. 4. 
 
 Char. Filaments about equal to those of V. fasciata. Cells 
 ticice or thrice as long as broad. Sporangia contained in 
 cells of a compressed ellipsoidal form. 
 
VESICULIFERA. 205 
 
 Vesiculifera compressa Hassall, in Annals of Nat. Hist., 
 
 vol. X. p. 393. 
 Hab. In a pond in Yorke's Brickfield, near Cheslumt : 
 
 A. H. H. 
 
 The inflations in this species resemble in form the knobs 
 of dumb-bells. 
 
 23. VeSICULIFEEA INiEQUALIS. 
 
 Plate LIII. Fig. 2. 
 Char. Filaments in a state of reproduction of very unequal 
 diameter. Cells varying in length, being sometimes four 
 or Jive times as long as broad, at others only three times ; 
 these variations occurring usually on different parts of the 
 same filament. Sporangia circular, lodged in cells which 
 present an hexagonal appearance, empty cell next the spore 
 larger than the rest. 
 Hab. Cheshunt : A. 11. H. Eusthall Common and Bur- 
 wash : Mr. Jenner. 
 
 This appears to me to be a very distinct species ; it is sub- 
 ject, however, to considerable variation. It, as well as the 
 following, is very common, and both were procured by Mr. 
 Jenner, INIr. Kalfs and myself within a very short time of 
 each other. 
 
 24. Vesiculieera jequalis Hass. 
 Plate LIII. Fig. 3. 
 
 Cha7'. Filaments of smaller calibre tha?i those of the preced- 
 ing species, of equal diameter. Cells about six times as long 
 as broad. Sporangia circular, lodged in cells which are 
 broader than long. 
 Hab. Cheshunt : A. H. H. Pvusthall Common and Del- 
 monden ; Ilawklmrst : 3Ir. Jenner. 
 
 This as well as the preceding species is found in boggy 
 pools which retain the water for a long time. 
 
206 CYSTOSPERME^. 
 
 25. Vesiculifera flavescens Hass. 
 Plate LIII. Fig. 9. 
 
 Char. Filaments about equal in size to those of V. crispa. 
 Cells four or Jive times as long as broad. Si3orangia cir- 
 cular, lodged in cells of the same form. 
 Hab. Penzance : 31r. Ralfs. 
 
 Tliis species I have only received from Mr. Ralfs and Mr. 
 Jenner. 
 
 26. Vesiculifera affinis Hass. 
 Plate LIII. Fig. 1. 
 
 Char. Filaments about equal in size to those of V. vernalis. 
 Cells ^ue or six times as long as broad. Sporangia cir- 
 cular, lodged in cells lohich are slightly ovate and protube- 
 rant at the sides. 
 Hab. Clieshunt : A. H H. 
 
 Not an uncommon species, perhaj)s, but a variety of V. 
 vernalis. 
 
 27. Vesiculifera hexagona Hass. 
 Plate LIII. Figs. 11, 12. . 
 
 Char. Filaments somewhat stouter than those of V. cequalis. 
 Cells three or four times as long as broad. Sporangia cir- 
 cular, contained in inflated cells of an hexagonal form. 
 Hab. Cheshunt: A. H. H. 
 
 This is a very distinct little species, and not uncommon : 
 a variety occurs with filaments considerably finer. This may 
 also be distinct. 
 
 28. Vesiculifera dubia Hass. 
 
 Plate LIII. Fig. 14. 
 
 Char. Filaments of the same size as those of V. hexagona. 
 
VESICULIFERA. 207 
 
 unhiflated. Cells usually Jive times as long as broad. 
 Sporangia circular, lodged in inflated cells of a someiohat 
 hexagonal form, but much larger than those of V. hexa- 
 gona. 
 Hab. Penzance: Mr. Ralfs. 
 
 This species approaches rather closely to V. hexagona, from 
 which, liowcver, I think that it is distinct. 
 
 29. Vesiculifera Mulleri Hass. 
 Plate LIII. Fig. 10. 
 
 Char. Filaments more slender than those of V. fasciata. Cells 
 fullg four times as long as broad. Sporangia spherical, 
 contained in inflated cells of a regularly globular form. 
 Vesiculifera JSIulleri Hassall, in Annals and Mag. of Nat. 
 
 Hist., vol. X. p. 393. 
 Hab. Cheshimt : A. H. H. Rusthall Common and 
 Hawkhurst : Mr. Jenner. 
 
 This species is by no means common ; I have never met 
 with it but once. 
 
 30. Vesiculifera Bosch Hass. 
 Plate LII. Figs. 3, 4, 5. 
 Char. Filaments slender. CeUs about six times as long as 
 broad. Sporangia oval, contained in greatly enlarged cells 
 of the same form. 
 Prolifera Boscii INI. Leon le Clerc, loc. cit. t. 25. f. 5. V. 
 elcgans Hass., Annals, vol. x. Conf. tumidula, Eng. 
 Bot. 1670. 
 Hab. Henfield: 3Ir. Borrer. Rusthall Common: Mr. 
 
 Jenner. 
 There is not a more distinct or prettier species than this 
 in the genus. 
 
 I do not know whether figs. 4, 5. pi. 52. are to be regarded 
 as varieties of this or distinct species. 
 
208 CYSTOSPERMEiE. 
 
 31. Vesiculipera alata Hass. 
 Plate LIII. Fig. 8. 
 
 Char. Filaments scarcely exceeding those of V. Rothii in size. 
 Uninjiated cells about six times as long as broad. Spo- 
 rangia oval, having their long diameter placed in the axis 
 of the diameter of the inflated cells, such bearing cells very 
 protuberant laterally. 
 Hab. Penzance: Mr. Ralfs. 
 
 This is one of the most remarkable siDCcics of the genus, 
 and the only specimens which I have seen of it are those 
 transmitted to rae by Mr. Ralfs. 
 
 32. Vesiculifera Rothii Hass. 
 Plate LIII. Fig. 7. 
 
 Char. Filaments rather more slender than those of the pre- 
 ceding species. Cells fully four times as long as broad. 
 Sporangia rather broader than long, contained in inflated 
 cells of the same form. 
 
 V. bombycina Hassall, in Annals of Nat. Hist., vol. x. 
 p. 394. Conf. bombycina Ag. Harv. Manual, p. 126, 
 Prolifera Rothii M. Leon le Clerc, Mem. du Mus. 
 
 Hab. Everywhere common. 
 
 Three or four cells sometimes occur in juxtaposition. 
 
 33. Vesiculifera Candollii Hass. 
 Plate LII. Fig 9. 
 
 Char. Filaments of about the same diameter as those of V. 
 crisjja. Cells usually six times as long as broad. Sporangia 
 circular, contained in inflated cells zvhich are someiohat 
 narrower at one extremity than the other. 
 V. vernalis Hassall, in Annals of Nat. Hist., vol. xi. p. 434. 
 Prolifera Candolli M. Leon le Clerc, Mem. du Museum, 
 t. 25. fis:. 7. 
 
BULBOCHJKTE. 209 
 
 Hab. Walthara Abbey and High Beech, Ejiping : A. H. H. 
 Rusthall Common : Mi: Jenner. 
 
 This is a distinct as well as common species. I have but 
 little doubt of tlie correctness of the synonym. 
 
 17. BULBOCH^TE ^^. 
 
 Char. Filaments attached, of equal diameter, branched. Cells 
 truncate, sctiyerous, the seta being rigid, elongated, and 
 bulbous at their bases. Reproductive bodies situated 
 either in injiated cells, when they are formed by the union 
 of the contents of two contiguous cells, or in the bulbous 
 portio7is of the seta, which become much enlarged for their 
 accommoda tion. 
 Derivation. From ^o\Bos, a bulb, and %aiT?;, a bristle. 
 
 The reproduction of this remarkable genus has, until very 
 recently, been wholly unknown. ]\I. Decaisne, in his ISIemoir 
 on the Classification of the Algre, contained in the numbers 
 of the " Ann. des Sciences Nat." for May and June 1842, 
 alludes to the mode of formation of the reproductive bodies 
 by the union of the matter of two cells in the same filament, 
 but does not appear to have noticed the second way in which 
 they are formed, viz. within the bulbous portion of the seta. 
 The observations of INI. Decaisne and my own remarks appear 
 to have been made nearly at the same period. 
 
 " In the above account of the reproduction of the genus 
 Bulbochate I have avoided using the term spore to designate 
 the condensed endochrome in the inflated cells, which presents 
 so much the appearance of a true spore ; for I conceive that it 
 is most probable that this separates, as in the other branched 
 species of Conferva, into numerous small reproductive gra- 
 nules. 
 
 " The genus Bulbochcete may be regarded as forming the 
 connecting link between the simple and branched freshwater 
 Conferva ; it agreeing with the Conjugata in the equality of 
 its filaments, with the Cystospermca in the union of the con- 
 tents of two distinct cells, and probably with the branched 
 p 
 
210 CYSTOSrERME^. 
 
 species in the separation of the condensed endochrome in 
 the inflated cells into numerous reproductive vesicles."* 
 
 1. BuLBOCHiETE SETIGERA Ag. 
 
 Plate LIV. Figs. 1, 2, 3, 4. 
 
 Char. Filaments dichotomously branched^ tufted. Cells 
 usually Jive times as long as broad. 
 
 B. setigera Harvey, in Hooker's Brit. Flor. ii. p. 350. ; 
 also in Manual, p. 121. Conf, vivipara Dillw. t. 59. ; 
 Hassall, in Annals, xi. p. 362. 
 
 Hab. Common in boggy pools. 
 
 Bulhochate setigera has by most systematists been placed 
 in the same family of Alga with Chatophora and Drapar- 
 naldia, the presence of cilia on the filaments having been 
 the chief inducement so to do. It is certainly to be re- 
 garded as the connecting link between the branched and 
 simple freshwater AlgcB ; but it exhibits a closer relation to 
 Vesicidifcra than to any genus of branched Conferva, it 
 agreeing with it in the mode of formation of the sj)ores, 
 and in its rigid habit. The next genus to which it appears 
 closely allied is Cladophora, of which Conf. glomerata, C. 
 fracta, &o. are examples. This genus has the same rigid 
 character, though in a less degree, as Bulbochcste and Vesi- 
 cidifcra. In a natural arrangement, these genera should 
 follow each other somewhat in the following order : — Vesi- 
 culifera, BidbochcBte, Cladophora, and then Coleochate, ChxB- 
 tophora, Drajmrnaldia, Spharoplea, &c. 
 
 ** On freshwater plants, &c., in lakes and ponds. Tufts a 
 quarter to half an inch high, forming dense villous tufts. 
 Filaments irregularly and slightly branched ; the branches 
 subalternate or dichotomous, either erect or recurved, jointed. 
 Joints three or four times as long as broad ; swollen up- 
 wards, from their upper part bearing a long inarticulate deci- 
 duous bristle, whose base is expanded, and half clasping the 
 
 * Hassall, in Annals of Nat. Hist. vol. xi. 
 
BULBOCH^TE. 211 
 
 joints ; substance subgelatinous ; Avlien recent, somewhat 
 horny ; when dry, colour dull greenish brown, fadhig to grey 
 in the lierbarium. A curious plant of doubtful affinity ; 
 under the microscope, resembling a Sei'tidaria set with herring 
 bones." — Harv. 
 
 Tliis species is either very variable, or else several species 
 have been confounded together. I have noticed three varieties 
 or conditions : — 
 
 Var. 1. with cells three times as long as broad. 
 
 Var. 2. with cells once or once and a half as long broad. 
 
 Var. 3. filaments very small, cells five times as long as 
 broad. 
 
 " Mais la sexieme famille me parait bien plus obscure, et je ne I'offre 
 aux naturalistes qii'avec repugnance. Cette reproduction par bourrelets, 
 toute conforme qu elle parait aux loix de la nature, me cause toujours 
 quelque peine quand je I'annonce. Elle me semble plutot devoir ctre 
 consideree comme iin moyen surabondant, que comme une forme particu- 
 liere, qui distingue certaines especes. Et en eifet en trouve peu de 
 plantes qui ne se multipllent de cette maniere, en meme temps qu'elles se 
 propagent par leur graines. Cependant jusqu'a present, je n'ai jamais 
 A'u les Conferves de cette famille s'accroitre autrement, et d'autre part je 
 n'ai jamais vu les Conferves des autres families se multiplier de cette 
 maniere, j'eu excepte cependant la Conferva glomerata Linna^i, sur les 
 debris de laquelle j'ai quelquefois rencontre des brins verts, qui etoieut de 
 nouveaux dcveloppements, Je rccommande done les prolif cres en parti- 
 culier aux observations des botanistes, pour qu'ils y cliercbent des organes 
 sexuels, et qu'ils tacbent de reconnoitre si, independamment des bour- 
 relets, elles renferment des graines. La Confcrve rimlaris est tres com- 
 mune et tres facile a observer ; les graines brillans dout elle se pourvue 
 doivent donner quelque soupfon, et faire conjecturer que son organis- 
 ation est plus composee que je ne I'ai dit. De mon cote, autant que 
 j'aurai du loisir et de la sante, je ne regarderai pas mon taclie comme 
 acbevee ; j'observerai cette famille plus attentivcment que je n'ai fait 
 jusqu'a present. J'en isolerai quelques individus, et j'espere qu'aide des 
 lumieres que me fournira sans doute la publication de cct ouvrage, je 
 decouvrirai enfin la reproduction de cette famille, si du moins elle en a 
 une qui lui soit propre, independamment de ses bourrelets." — Vaucher. 
 
212 
 
 Fam. X. MONOCYSTEiE. 
 
 The reproduction of this family agrees precisely with that 
 of Chcetophora and Draparnaldia, and perhaps Batrachosper- 
 vmm, which genera it Avould perhaps haA^e been more natural 
 that it should have been made to follow. 
 
 It consists of three genera of freshwater AlgcB, CladopJiora 
 Klitzing (a genus synonymous with my genus 3Iicrosj)ora), 
 ColeochcBte, and Lynghya. 
 
 In the species of this family %ve have no union and inter- 
 mingling of the contents of two cells, but each cell contains 
 all the requisites for the perpetuation of the species, viz. 
 zoospores and the fertilizing vesicles. 
 
 AVhen the zoospores have been fertilized, the cells swell 
 up, the increase in the size of the cells being determined by 
 the developement of the zoospores, and which developemeut 
 proceeds to such an extent as to occasion the rupture of the 
 membranes of the cells, the zoospores escaping through the 
 apertures thus formed. 
 
 This inflation of the reproductive cells of the branched 
 Confervce and of the LynghycB does not appear to have been 
 noticed by any other observer save Yaucher, and by him only 
 in the Batrachosperms ; and yet it is of frequent occurrence, 
 and affords a character whereby species may be often dis- 
 tinguished from each other, although at the same time it 
 changes the ordinary appearance of the species so much as to 
 lead sometimes to the description of specimens so altered as 
 distinct species ; and this has doubtless been the case with 
 Conferva fracta of the " Flora Danica," which is C. crispata 
 in a state of reproduction. 
 
 The species of this family are for the most part attached, 
 and present the double mode of growth described in the In- 
 troduction, viz. that of longitudinal and lateral developement 
 of the cells. 
 
CLADOPHORA. 213 
 
 Sub-fam. i. Clabophoreje. 
 
 18. CLADOPHORA Kutz. 
 
 Char. Filaments attached, much branched, not sctigerous, 
 and not invested zcith secondary cells. 
 
 Derivation. From kKoBos, a branch, and ^opsw, to bear. 
 
 This important genus I established in the " Annals of Nat. 
 Hist." vol. xi. p. 363., under the name of 3Iicros]wra. Sub- 
 sequently finding the same genus to have been characterised 
 by Kiitzing in his " Phycologia Generalis," I have been in- 
 duced to adopt his generic name, it appearing to be the more 
 approiDriate. 
 
 The genus should contain amongst the freshwater Conferva 
 C. glomerata and C. crisjyata, and the majority of the marine 
 branched ConfervcB. Conf. area and its numerous allies 
 should form another genus, agreeing in its reproduction 
 closely with Cladoj^hora, but differing from that genus in 
 the simplicity of its filaments : this genus might be deno- 
 minated Aplonema.* The filaments when dry are destitute 
 of gloss, like those of the Cystospermeoe, and do not adhere 
 well to paper. 
 
 1. CLADOPHORA GLOMERATA. 
 
 Plates LYI, LVII. Figs. 1, 2. 
 
 Char, Filaments tufted, bushy ; sometchat rigid, bright p-een, 
 shining. Branches crowded, irregular, erect ; the ultimate 
 ramuli secund, subfasciculate. Articulations /owr to eight 
 tijnes longer than broad. 
 
 a glomerata Dillw. Conf. t. 13.; Eng. Bot. t. 2192.; 
 Manual, p. 134. Microspora glomerata Hassall, in 
 Annals, vol. xi. C. Broivnii Harv. 1. c. p. 356. ; also 
 in Manual, p. 134. ; Dillw. Suppl. t. D. C. pulvinata 
 Brown, ]\IS.; Wyatt, Alg. Dan. No. 225. C. a-gagro- 
 
 * From oTrXor, simple, ami r>iitn, a thread 
 p 3 
 
214 MONOCYSTE^. 
 
 pila, E. Bot. t. 1377. ; Dillw. Conf. t. 87. ; Harv. 1. c. 
 p. 357. ; also in Manual, p. 134. 
 Hah. C. glomerata, common in streams and Avells. — C. 
 (Bgagropila, in lakes, rare. North Wales : Rev. M. 
 Davies. North of Scotland : M7\ Brodie. Prestwick 
 Car : Mr. Winch. Culmere Pool and Whitemore, 
 Shropshire : Rev. E. Williams. Cunnemara : Mr. Mac- 
 hay. — C. Brownii. On wet rocks, in a cave near Dunree, 
 North of Ireland : R. Brown, Esq. On shady rocks at 
 the entrance of a small cave beyond Black Castle, 
 Wicklow, where it is exposed to the dripping of fresh 
 water, and occasional overflow of the sea: W. H. Harvey. 
 Cornwall coast, near the Land's End : Mr. Ralfs. 
 
 This beautiful and abundant Conferva delights in pure and 
 running waters, attaching itself to stones. Avails, and piles in 
 streams, rivers, and cascades, it being drawn out by the cur- 
 rent often to more than two feet in length. In the mass, it is of 
 a deep and refreshing green colour, which is occasioned by the 
 purity of the water in which it lives. Examined separately, 
 the filaments present a peculiar glistening appearance, rare 
 amongst freshwater Algce, though common to many marine 
 species. Not infrequently, the branches are beset w4tli tufts 
 of ramuli, which, Avhen the plant is floated out in water, give 
 it somewhat the appearance of a Sertularia, and increase 
 greatly its beauty. It is in this species that I have seen the 
 apertures situated on one side of the distal extremity of 
 the cells designed for the escape of the zoospores. Notwith- 
 standing that its usual resort is the stream and the waterfall, 
 it will flourish and increase in size amazingly for weeks and 
 months in a vessel, the water of which is occasionally re- 
 newed. I have thus kept it for many weeks, removing, Avhen 
 by its growth it had filled the vessel, all but a small portion 
 of it ; this, however, speedily increased, and again filled its 
 dwelling-place. The tearing away of portions of the plant 
 in no way impaired the vitality of the remainder, as from its 
 aggregation of minute cells, each the analogue of the other, 
 might a priori have been conjectiu-ed. 
 
CLADOPIIORA. 215 
 
 After the species has been thus confined for some time, if 
 it be examined with a glass, very many of the filaments 
 will be found to be invested with numerous smaller fila- 
 ments. These are the young of the plant derived from the 
 growth of the zoospores, which have attached themselves to 
 the parent filaments. It was the occurrence of a specimen 
 thus infected that induced Vaucher to place this species in 
 his genus Prolifera. 
 
 This species is the favourite resort of Diatoma vulgare^ 
 Avhich attaches itself to it by means of a distinct root-like 
 organ. The Diatoma frequently developes itself over the 
 filaments to such an extent as totally to obscure their rich 
 green colour. A brown no less rich is imparted to it by the 
 l^arasite. 
 
 The two following plants, old and established as the one of 
 them at least would appear to be, I regard as conditions of 
 CladophoTa ghmerata — viz. C cegagroinla and C. Broitmri. 
 The microscope does not present any essential difference in 
 the structure of these supposed, though I believe erroneous, 
 species. The state of Cladophoi-a ghmerata (which has received 
 a distinct name even at the hands of the great Swede himself) 
 (^Cagagropila Linn.), I believe to be formed as follows: — 
 a specimen by the force of some mountain stream swollen by 
 recent rains becomes forced from its attachment ; as it is car- 
 ried along by the current, it is made to revolve repeatedly 
 upon itself, until at last a compact ball is formed of it, which 
 finally becomes deposited in some basin or reservoir in which 
 the stream loses itself, and in which these balls are usually 
 found. 
 
 The size of these balls varies from two to four inches ; they 
 are dense, firm, and spongy. Kiitzing has carried his idea 
 of this species to such an extent as to constitute for its re- 
 ception a new genus, taking for the generic name the old 
 specific appellation of agagropila, and bestowing upon it the 
 specific name of its renowned discoverer Linna3us — JEga- 
 gropila Linncei. The term (pgagropUa is derived from its 
 resemblance to the balls that are found in the stomachs of 
 goats. The peculiarities of the second condition of C. gh~ 
 
216 MONOCYSTEiE. 
 
 merata (C Brownii) arise from tlie sub-immersed habitat in 
 which it grows. Mr. Harvey thus describes C. Brownii : — 
 " This forms exceedingly dense, very rigid tufts, of a black 
 green colour when growing, but on having the water 
 expressed, and being held to the light, exhibits a beautiful 
 yellow-green tint. Filaments so matted together, that it is 
 difficult to separate a single thread. They appear to ori- 
 ginate in a mass of creeping, branched, densely matted fibres, 
 which form the base of the tufts. They are erect, from half- 
 an Inch to an inch high, flexuous, very rigid and elastic ; the 
 branches few and nearly simple, almost always secund, very 
 erect. A very curious and distinct plant, having, to the 
 naked eye, a good deal the appearance of Vaucheria tei-restris, 
 but totally different in structure. It is perhaps allied to C. 
 (Bgagropila. I have examined a specimen from i\Ir. Brown in 
 the late INIr. Templeton's herbarium, and find it to agree in 
 every respect with my WickloAV plant." 
 
 2. Cladophora crispata. 
 
 Plate LV. Figs. 1, 2. 
 
 Char. Filaments very tenacious and of variable diameter, 
 ci'isped, and entangled. 
 
 C. nigricans Dillw. Conf. Syn. 1. c. ; Harv. 1. c. p. 356. 
 C. crispata Sm. E. Bot. t. 2350 ; Harv. 1. c. p. 356. 
 C. Jlavescens Harv. 1. c. p. 356. ; E. Bot. t. 2088. ; 
 Wyatt, Alg. Darm. No. 224. C. fracta Dillw. Conf. 
 t. 14. ; E. Bot. t. 2338. ; Harv. 1. c. p. 356. Micro- 
 spora Hass. in Annals, vol. xi. 
 Hob. Everywhere common. Var. nigricans in a pond at 
 Wimbledon,. Surrey : Mr. Dickson. 
 
 Three British species of Conferva appear all referrible to 
 this one: these are C. nigricans, C. fracta, and C Jlavescens. 
 C. Jlavescens I take to be the young state of C. crispata, 
 while C. fracta is assuredly the mature or perfect condition 
 of the plant : it is also equally certain that the C. nigricans 
 of Dickson Is merely a discoloured state of C. crispata. 
 
COLEOCH^TE. 217 
 
 The suspicion also may, I think, be entertained, that C. 
 crispata Itself Is but a condition of C. glomerata, changed by 
 the difFerence of Its place of growth — It growing for the 
 most part In still Avater, in deep ponds, and lakes. I have 
 often seen specimens, which it would be Impossible to refer 
 Avith certainty to either species. A specimen of C cajnllaris 
 in the Llnnajan Herbarium, was refcrrible to this species, or 
 condition of one. 
 
 19. COLEOCH^TE 7?rc5. 
 
 Char. " Frond disciforin, apprcssed, parasitic, formed of fila- 
 ments radiating from a centre, generally conjoined. Fila- 
 ments articulated, dichotomously branched, sending forth 
 in all directions from the 2ipper surface of the cells cylin- 
 drical, truncated, lengthened, setigerous sheaths. Endo- 
 chrome green.''^ — Breb. 
 Derivation. From ko\so9, vagina, and X'^^'^Vi ^<^^^' 
 
 1. COLEOCHiETE SCUTATA Brcb. 
 
 Plate LXXVII. Fig. 6. 
 
 Char. Filaments appressed, conjoined, radiating, so as to 
 describe a disciform frond. 
 ^ soluta. — Filaments radiating, prostrate, free. 
 Coleochate sciitata Breb. Description de deux nouveaux 
 Genres d'Algues fliivlatiles, Ann. des Scien. Nat., Jan- 
 vier, 1844, p^. 25. pi. 2. 
 
 Hab. In stagnant waters and ditches, growing on sub- 
 mersed leaves and stems of aquatic plants. Autumn — 
 spring. Near INIanchester: il/r. Sidebotham. Aber- 
 deen : Dr. Dickie. Near Clonmel : Prof. G. J. Allman. 
 
 " I have found this remarkable Alga in many places in 
 the environs of the town of Falaise. It grows closely applied 
 upon the leaves and stems of inundated and in part decom- 
 posed plants. I have gathered it princi])ally upon Sparga- 
 nium nutans, and upon the Potamogdon nutans. Its lenticular 
 
218 MONOCYSTE^. 
 
 fronds may be easily clistingiilslied with the naked eye in 
 spite of their smallness, their green colour trenching upon the 
 discoloured parts of the plants upon which they are fixed. 
 At first sight one might be induced to believe that they are 
 but parts of those plants whose chromule has not been dis- 
 organised by the immersion which has discoloured their other 
 parts. These rosettes follow the forms of their supports. I 
 have seen them upon Conferva fracta ; they then embrace the 
 filaments in such a manner as to surround them with a sort 
 of ferrule or annular hood. A slight magnifying power of 
 the microscope is suflScient to show the elegant disposition of 
 radiating filaments which, by their approximation and lateral 
 union, resemble an areolated disc, which recalls to mind cer- 
 tain Pediastra belonging to the Desmidece. 
 
 "The fronds are roundish, from one to two, rarely three mil- 
 lemetres in diameter ; they are formed of filaments closely ap- 
 plied to the plant on which they grow, dichotomously branched ; 
 branches approximate, and as though soldered the one to the 
 other. The articulations or cells three or four times as long 
 as broad, often unequal, are furnished interiorly with a green 
 granular endochrome. On a great number of these articula- 
 tions is remarked a tubercular rounded projection or pro- 
 tuberance, from which arises a tubular filament, truncated a 
 little, dilated at the summit, from the interior of which issues 
 a long and very delicate thread. This part of the organiza- 
 tion of this Alga shows clearly that it ought to be placed in 
 the Ch(Rtoplioroide(B, and near to Bidhocliate. This setifer- 
 ous sheath is very caducous and difficult to j^erceive. 
 
 *' At a certain period of the existence of Coleochcete scutata 
 its disc is covered here and there Avith tuberculated masses of 
 endochrome, which one might regard as the formation of 
 spores, at a later period indeed, these little masses are con- 
 verted into groups of globules charged with the tube or seti- 
 ferous sheath which characterizes this Alga. In the first 
 period of its developement, the tubes terminate in a point, 
 from whence issues a long setaceous filament of great te- 
 nuity ; at a later period, the summit of this sheath is open, 
 and appears then truncated and slightly dilated. 
 
LYNGBYA. 219 
 
 "About the globule which is at the base of this shenth, are 
 developed, in the form of a rosette, the first articulations of 
 the filaments, as is seen mjig. 7. They are cuneiform ; some 
 slightly bi-lobed, give origin to two cells, and so determine the 
 dichotomy of the filaments. 
 
 " The variety, (B soluta, which I have sometimes found 
 amongst examples of the ordinary type, might be considered 
 as another species on account of its filaments, which are not 
 depressed, and are free in their whole length, but certain 
 fronds of the ordinary type may be regarded as connecting 
 the two forms ; I therefore do not think that they can be 
 separated. I have always observed that the filaments of the 
 variety /3 do not preserve, in ramifying, a dichotomous dis- 
 position so exact as in Coleochccfe scutata, 8:c." 
 
 In all those specimens of this most interesting production 
 which I have examined, the sheaths and cilia have been al- 
 together Avanting. In some cases, however, the point of 
 attachment of the sheaths to the cells could be perceived. 
 The natural position of the genus is certainly near to Bulho- 
 chcste. 
 
 Sub-fam. ii. TJlothriceje. 
 
 20. LYNGBYA Ag. 
 
 Char. Filaments simple, subulate, and shining. Zoospores 
 several in each cell, escaping through rents in the tcalls 
 of the cells. 
 Sphceroplea Berk. Ulot'krix Kiitzing, Phyc. Gen. p. 251. 
 
 Sph<eroplea Kiitzing, 1. c. 
 Name in honour of 31. Lynghyc, author of an excellent 
 work on the Alg(B of Denmark. 
 
 The genera Lynghya and Spharoplea are undoubtedly 
 identical, and one of the terms must of necessity be sup- 
 pressed. Bangia also differs but slightly from the genus 
 Lynghya, and its abolition seems called for. Kiitzing has 
 constituted a new genus for the reception of Conf. zonata 
 {SphcBroplca crispaHerl:.), Ulothrix, preserving also the genus 
 Sphceroplea, the type of which he makes Cojif. anmdaria Roth. 
 
220 MONOCYSTE^. 
 
 I cannot discover the necessity for the genus Ulothrix. Kiit- 
 zing's definitions of the genera JJlothrix and Sphocroplea are as 
 follow : — 
 
 Ulothrix — " Trichoma simplex, membranaceum, tener- 
 rimum, flaccidum; cellulte gelineae, tenuissima3, hyalinaj, ach- 
 romaticEe, abbreviatfe: amylideaj delicatissimje, virides, ple- 
 rumque granuliferse, primo extenste, dein paulatim in fascias 
 transversales contractte, tandem in opseospermata quatuor vel 
 pliii'a hologonimica transeuntes." 
 
 Sphl^roplea. — " Trichoma parenchymaticum simplex, 
 cellulffi tenuissimte merabranaceje, substantia chlorogonomica 
 demum in spermatia transeunte repletie, spermatia i^rimo 
 viridia deinceps miniate fusco : epispermio duplici, exterior! 
 filiformi, internum spiraliter investiente, cuncta in series longi- 
 tudinaliter digesta." 
 
 The endochrome in all the species of this genus in the 
 young condition is almost uniform ; subsequently, however, it 
 parcels itself into numerous zoospores in each cell. The 
 same remark applies to all the AlgcB, which are multiplied by 
 means of zoos^oores. 
 
 Tlie species described in this genus might with some pro- 
 priety be divided into two subgenera, in the first of Avhich 
 should be placed Lynghya zonata, L. muralis, L. virescens, L. 
 Thompsoniy and L. copulata, in which the filaments are almost 
 always attached, are of a delicate and fragile nature, of a deep 
 green colour, and delight in pure water ; while in the second, 
 Lynghya Jloccosa, L. punctalis, and L. vermicular is, should 
 be ranged, these being distinguished by characters the very 
 reverse of those just enumerated, they being rarely attached, 
 tenacious, of a dull green colour, and inhabitants of impure 
 waters. In this division L. prolijica should also find a place. 
 
 1. Lyngbya zonata Hass. 
 
 Plate LIX. Figs. 4, 5, 6 and 1, 2, 3. 
 
 Char. Filaments of considerable diameter. Cells usually 
 rather longer than broad, but sometimes shorter. Endo- 
 chrome at first quadrangular, not entirely filling the cavity 
 
LYNGBYA. 221 
 
 of the cell, but leaving a pellucid margin all around, sub- 
 sequently becoming globular and granular. Zoospores six 
 or eight in each cell. 
 Conf. zonata Web et Morli. Conf. lucens Dillw. t. 47. 
 Conf. bicolor, E. B. t. 2288. Spharoflea crispa Berk. 
 Glean. Algje, t. 3. fig. 1. 
 
 This species delights in pure and running water, it growing 
 luxuriantly in that of cascades and waterfalls. It is every- 
 where common throughout Great Britahi. Considerable con- 
 fusion seems to have prevailed relative to this plant, several 
 observers having repeatedly described it imder different names. 
 I have no doubt whatever of the correctness of the syuonymes 
 quoted. The form of the cells in this species is somewhat pecu- 
 liar. They are not exactly cylindrical, but taper gradually 
 from each extremity towards the centre of the cell, the ex- 
 tremities, or angles of the cells appearing in consequence 
 prominent. 
 
 Two varieties of It have presented themselves to mc ; the 
 one at Snaresbi'ook, Essex, in great quantity ; this agree- 
 ing with the species proper In all, save the length of the 
 cells, which are generally two and a half or three times as 
 long as broad ; the other in a stream at Wood Green, near 
 Cheshunt, in which the cells are cylindrical, completely filled 
 with endochrome, and not one third so long as broad. This 
 may be distinct. 
 
 2. Lyngbya muralis Ag. 
 
 Plate LIX. Fig. 7. 
 
 Char. Filaments of less diameter than those of Lynghya 
 zonata, darh green, entangled. Cells very short, tico or 
 three times broader than long. 
 
 Hah. On the ground in all damp situations early in the 
 spring. 
 
 This is a very distinct species, rendered interesting from 
 the peculiarity of its habitat. The diameter of the filaments 
 
222 MONOCYSTEJ5. 
 
 and length of the cells vary considerably, according to the 
 age of the plant. 
 
 3. Lyngbya copulata Hass. 
 Plate LXXII. Fig. 14. 
 
 Char. Filaments very flexible, of about the same diameter 
 as those of L. muralis, adherent to each other for a con- 
 siderable portion of their length. Cells short. 
 
 L. muralis var. copulata Carm. MS. 
 
 Hab. Appin; Captain Carmichael. 
 
 This is a very curious production, exhibiting some relation 
 in the adherence of the filaments the one to the other to 
 Calothrix mirabilis — than which it is not less wonderful. 
 It is very rare. 
 
 4. Lyngbya virescens Hass. 
 
 Plate LX. Fig. 3. 
 
 Char. Filaments of about the same diameter as those of L. 
 punctalis. Cells usually somewhat beaded, rather longer 
 than broad. Endochrome not quite filling their cavities. 
 Hab. On stones, in a pond, near Wanstead Flats, Essex : 
 A.H.H. Penzance: Mr. Ralfs. 
 
 This S23ecies, except in the simplicity of its jSlaments, bears 
 a very close rjesemblance to the Draparnaldia. Like the 
 species of that genus, it is of a beautiful green colour, fragile, 
 slippery to the touch, and delighting in pure and slowly run- 
 ning waters. The filaments are always attached, in which 
 respect it agrees with L. zonata. 
 
 5. Lyngbya Thompsoni Hass. 
 
 Char. Filaments attached, exceedingly slender. Cells once or 
 twice as long as broad. 
 Meloseira Thompsoni Harv. in Manual, p. 195. 
 
LYNGBYA. 223 
 
 Hah. Growing on stones in a mountain rivulet at Bal- 
 lautrae, Ayrshire: Mr. W. Thompson. 
 
 This is clearly a Lyyigbya, and the most minute species of 
 the genus with wluch I am acquainted. It is described as 
 forming " beautiful, glossy, dark green tufts." 
 
 6. Ltngbya floccosa Hass. 
 
 Plate LX. Figs. 1, 2. 
 
 Char. Filaments of smaller diameter than those of L. muralis. 
 Cells at first cylindrical, subsequently headed, rather longer 
 than broad. 
 Conf. floccosa Ag. Conf fugacissima Dillw. Sup})., t. B. 
 C. floccosa Harv. Manual, p. 126. 
 
 This sjjecies is very distinct and abundant, being found 
 in great quantities in almost all ponds, on heaths and bogs. 
 The filaments are rarely attached, are highly mucous and 
 tenacious. When kept in Avater it does not quickly pass to 
 decay. Specimens are often met with, which when placed 
 under the microscope appear quite colourless, the cndochrome 
 having escaped from the cells. 
 
 7. Lyngbya punctalis Hass. 
 Plate LX. Fig. 4. 
 
 Char. Filaments of less diameter than those of Lyngbya 
 floccosa, very mucous. Cells two or two and a half tiynes 
 as long as broad, slightly contracted. Endochrome at 
 first quadrangular, not filling the entire cavity of the cell, 
 arranged usually in two separate masses, but sometimes 
 there is but one ; subsequently the cells becoming inflated, 
 the cndochrome assumes a spherical form. 
 Sphccroplca piinctalis Berk. Glean. Alg. t. 3. fig. 2. Conf. 
 punctalis Dillw. t. 51. Sph. punctalis Ilarv. in jNIanual, 
 p. 144. 
 
224 aiONOCYSTEiE. 
 
 Hah. High Beech : A. H. H. Penzance : 3Tr. Ralfs. 
 Bogs at Fisher's Castle : 3l7\ Jenner. 
 
 This very beautiful species is by no means common. It 
 inhabits generally ponds on conmions and other exposed situ- 
 ations. 
 
 8. Lyngbya vermiculaeis Hass. 
 Plate LX. Fig. 5. 
 
 Char. Filaments very mucous, tenacious, and of a yellowish 
 yreen colour, finer than those of the preceding species. 
 Cells ticice or thrice as long as broad. Endochrome 
 rarely filling the cavity of the cell. 
 
 Hah. High Beech : A. H. H. Penzance : Mr. Ralfs. 
 
 Sussex : Mr. Jenner. 
 A common species in boggy pools. 
 
 9. Lyngbya prolifica Grev. 
 Plate VIII. Fig. 4. 
 
 Char. Filaments exceedingly slender, entangled, purple, very 
 broadly effused, fioating. 
 Grev. Crypt. Fl. t. 303. ; Harv. 1. c. p. 370. ; also in Manual, 
 
 p. 160. 
 Hab. In the loch of Haining, Selkirkshire, October to 
 
 April: Dr. Greville. 
 " Plant extensively diffused, forming a floating stratum, 
 of a rich purple colour. Filaments extremely slender, en- 
 tangled, somewhat rigid, yet flexible, entirely destitute of 
 attachment, and free from any mucous laj^er. Annuli from 
 the minuteness of the filament almost inconspicuous." — Gj-ev. 
 
 Note. — The following marine Algce I regard as members of the genus 
 Cladophora, — C. pellucida, C.rectangularis, C. Hutchinsia, C. diffusa, C. 
 nuda, C rupestris, C. Icctevirens, C. flexuosa, C. g?-acilis, C. rcfracfa, C. 
 albida, C. lanosa, C. uncialis, C. glaucescens, C. carta, C. cervginosa, and 
 C.riparia; while in Aploncma I place the subjoined Conferva, — arenicola, 
 sutoria, Limun, crassa, implexa, ulothrix, arenosa, melargoiiium, cerea, col- 
 labens, hangio'idcs, Youngana, and clandestina. 
 
225 
 
 Fam. XL HYDRODICTYONEiE. 
 
 21. HYDRODICTYON Roth: 
 
 Char, Cells arranged in the form of a pe7ita//on, an aggre- 
 gation of a number of these pentagonal meshes, going to 
 form an entire plant. Zoospores numerous in each cell, 
 and uniting together before the absorption of the parent 
 cell membrane. 
 Derivation. From vhcop, water, and Siktvov, a net. 
 
 1. Hydrodictyon utriculatum Both. 
 
 Plate LVIII. 
 
 Char. Same as those of the genus. 
 
 Harv. in Hook. Br. Fl. vol. ii. p. 359. Conf. reticulata, 
 E. B. t. 1687. ; DiUw. t. 97.; Vanch. Conf. cl'Ean douce; 
 Harv. Manual, p. 140. 
 
 Hab. In ditches and pools in the midland and southern 
 
 counties of England. In a pond in the Botanic Garden 
 
 at Cambridge, where it has existed for many years: 
 
 Rev. Prof. Hensloio. Not found in Scotland or Ireland 
 
 hitherto. 
 
 Hydrodictyon utriculatum is one of the most remarkable 
 
 of the freshwater AlgcB. The credit of the discovery of the 
 
 singular reproduction of this species is due entirely to 
 
 Vaucher, whose account of it is so clear and well expressed 
 
 that I cannot do better than translate his remarks: — Each of 
 
 the fine filets (cells) which form the pentagon begins to swell 
 
 a little, principally at the extremities, then it is separated 
 
 from the others not by a rupture, properly so called, but by 
 
226 HYDRODICTYONE^. 
 
 issuing from the interior of tlie membrane in which it was 
 contained, and which, without doubt, was open for the pur- 
 pose of its escape * ; and after this separation it floated on the 
 water under the form of a cylindi-ical cell. Soon it flattened 
 itself, and underwent an alteration, which I would com- 
 pare to that which the beginning of fusion produces upon 
 metals ; then it increased gradually in every direction, and, 
 the reticulations being cleared the one from the other, be- 
 came itself a new network, which one might distinguish 
 with the microscope. Soon the reticulations were to be seen 
 Avith the unaided sight, and at last each cell (or division of 
 the pentagon), was totally changed into a network entirely 
 like to that of which it made part. All these transformations 
 took place in the space of a few days, and at the end of two 
 or three months the young reticulated productions had acquired 
 
 the full dimensions of which they were capable 
 
 We have here then an example of reproduction more re- 
 markable perhaps than those heretofore observed." 
 
 " In conclusion, there is but little room to doubt that if the 
 sides of the reticulations of the network of the preceding 
 year be the networks of this year, the sides of the reticulations 
 of the present networks will also be the networks of the next 
 year, that each cell or fibre of the reticulations is itself the 
 network which shall develope itself on the second year, and 
 that the fibrilla of the principal fibre will be the network 
 which shall develope itself on the next year, and so on until 
 it please the Author of Nature to put an end to this deve- 
 lopement by destroying the species which presents it." 
 
 * Aresclioiig, who has published an excellent papei' in Schlechtendal's 
 "LinuEca," for 1842, on the mode of growth oi Hydrodictyon uMculatum, 
 states that he has never been able to detect in this plant the enclosing 
 tube. Dr. Areschoug has made the interesting discovery of the exact 
 mode of formation of the minute network, viz., by the union of the 
 numerous spores while in the i^arent cell, previously to which they are 
 observed to be in lively motion ; the parent cell itself is absorbed, and 
 thus the new plant is eliminated according to Areschoug. 
 
227 
 
 Fam. xii. SCYTONEME^. 
 
 Char. Algaj for the most j)art branched, rigid, or flaccid. 
 Cells globular or compressed. Colour either a darh olive 
 or a vivid ceruginous green. 
 
 The Alga described in this family form two very distinct 
 sections ; the first section embracing those species which are 
 characterized for the most part by a rigid cartilaginous habit, 
 globular cells, a black or olivaceous colour, being lustreless 
 iu drying, and the second division including species wlilch are 
 not of a rigid habit, but whose filaments are flaccid, cells usu- 
 ally cylindrical, and colour a vivid green. The species of this 
 last section Klltzing makes the type of his order Paraspcrmece, 
 an order characterized by its lateral sporulcs, and including 
 LynglyacecB and Cahthricece, fixmllies which follow in his 
 arrangement the Scgtonemece. 
 
 Section i. Stigoneme^. 
 22. STIGONEMA y^^. 
 
 Char. Filaments tufted, branched, of irregular diameter, car- 
 tilaginous. Cells moniliform, arranged in transverse lines. 
 Derivation. From arLjcov, dotted, and vrjfia, a thread. 
 
 There Is scarcely any necessity for this genus: the species 
 described In it Avould form a natural section of the genus 
 Hassallia. 
 
 1. Stigonema atrovirens Ag. 
 PI. LXVI. Fig. 1. 
 Char. Filaments tufted, coarse. Branches slighihj divided, 
 subacute. Rings mosthj formed of three cells. 
 *Q 2 
 
228 SCYTONEME^. 
 
 Conf. atrovirens DiUw. t. 25. Licheii pubescens, E. Bot. 
 t. 2318. ; Harv. in Hook. Br. Fl. ii. p. 363. St atro- 
 virens Harv. in Manual, p. 153. 
 
 Hah. On wet rocks forming the banks to the river 
 Diloris, near Neath, Glamoi'ganshire : Mr. Dillwyn. 
 Mountainous district; 14 miles west of Aberdeen: Dr. 
 Dickie. On wet rocks above the falls of Aberdylais, 
 Swansea : Gutch. 
 
 This species forms rigid lustreless and very dark tufts ; 
 the filaments are divaricately branched, the branches nar- 
 rower than the stem, and sometimes furnished with two or 
 three secondary ramuH. The larger divisions are dark brown 
 and opaque, the smaller vivid green, their terminations being* 
 marked with transverse lines, which indicate the divisions into 
 cells. The dense cartOagiuous sheath is most visible at the 
 terminations of the branches. 
 
 2. Stigonema mamillosum Ag. 
 Plate LXVI. Figs. 2, 3. 
 
 Char. Branches incrassated, sjnndle-shaped, the tico inferior 
 thirds densely mamillose on all sides. 
 Bangia mamillosa Lyng. t. 25. ; Harv. in Hook. Br. Fl. 
 p. ii. p. 363. Stig. mamillosum Harv. in Manual, 
 p. 153. 
 Hab. Rocky bottoms of subalpine rivulets, Appin : Capt. 
 Carmichael. Eagle's nest, Killarney : JV. H. Harvey. 
 Mountainous district ; 14 miles west of Aberdeen : 
 Dr. Dickie. 
 
 This forms continuous tufts several inches in diameter, 
 which are less rigid than in S. atrovirens ; the branches are 
 simple, their diameter being greatest in the middle, and beset 
 on all sides, for the two lower threads Avith mamillfe of 
 various sizes, and the cells of which are always cylindrical, 
 and not moniliform. These mamillai as well as tlie upper 
 
STIGONEMA. 229 
 
 third of the branches are frequently of a vivid green colour. 
 It is just jjrobable that this species is but a condition of the 
 previous one, the differences observed being occasioned by its 
 moister habitat. 
 
 3. Stigonema panniforme Harv. 
 
 Plate LXVI. Figs. 4, 5. 
 
 Char. Filaments dark broion, densely packed together, much 
 branched. Branches long, Jlexuous, obtuse. Cells an- 
 gular, in triple series. 
 
 Scytonema panniforme Carm. MS. ; Ag. Syst. p. 309 ? 
 Stigonema panniforme Harv. in Manual, j). 154. 
 
 Hab. On rocks at the mouth of Spar Cave : Capt. Car- 
 michael. 
 
 " Patches indeterminate, crust-like, velvety. Filaments so 
 closely packed that only their tops are visible above the crust, 
 very tough when dry, gelatinous when moist, cohering 
 strongly together, much branched ; branches long and flexuous, 
 divaricating, cylindrical, quite obtuse, not tapered. Granules 
 ternate, very obvious in all the main branches, less distinct 
 towards the tips. This entirely agrees in external character 
 and ramification with the Scytonema pianniforme of Agardh, 
 with an authentic s^iecimen of which I have compared Car- 
 michael's sjDecimen. The only difference I can perceive lies in 
 the generic character, and this I suspect depends on age, for 
 I find the apices of the branches simply striated, like a Cal- 
 othrix or Scytonema, and the smaller branches, for, at least, 
 part of their length, have the semi-punctate appearance of S. 
 ocellatum ; and it is only in their larger and main branches 
 that the punctated character is clearly visible." — Harv. 
 
 4. Stigonema interruptum Hass. 
 
 Plate LXIX. Fig. 2. 
 
 Char. Filaments thick, subulate, coriaceous, glaucous green, 
 Q 3 
 
230 SCYTONEMEiE. 
 
 cohering in tooth-like fascicles. Cells very short. Strise 
 strongly marked. 
 Calothrix interrupta Carm. MS. C. interrupta Harv. in 
 Hook. Brit. Fl. p. ii. jd. 368. ; Harv. In Manual, p. 158. 
 
 Hah. On mosses and llcliens, Appin : Capt. Carmichael. 
 Turk's Cascade, Killarney ; and Tobermorey in the Isle 
 of Mull: W. H. Harvey. MacliynUeth, N. Wales: 
 JSfr, Ralfs. Aberdeen : Dr. Dickie. 
 
 " Filaments about a line in length, of a glaucous green 
 colour, united into close erect tufts, spreading over the moss, 
 thick, tapering, cohering at the base, and sometimes through 
 their whole length. Internal mass here and there interrupted, 
 leaving short pellucid spaces resembling articulations. Stri« 
 close and conspicuous." — Carm. MS. 
 
 This species is certainly much more naturally placed in the 
 genus Stigonema than in Calothrix. Owing to the compact- 
 ness of the cells they do not exhibit the dotted or monili- 
 form arrangement of the other species — a difference surely 
 not generic. The colour is a light glaucous green. 
 
 5. StigonejMA minutum Hass. 
 Plate LXVII. Figs. 3, 4. 
 
 Char. Filaments minute, erect, rigid, Jlexuons, fastigiate. 
 Branches short. Cells or rather sporulcs in the p7-i?icipal 
 filaments numerous, iii the branches in single series. 
 Scytonema minutum Ag. 8. minutum Harv. in Hook. 
 
 Brit. Fl. p. 365. ; Harv. in Manual, p. 155. 
 Hab. On rocks and crustaceous lichens ; common In al- 
 pine districts, Appin : Cajjt. Carmichael. Caroigataha 
 near Caher, and at Killarney : W. H. Harvey. 
 
 " Plant either spreading In a black suborblcular crust or 
 scattered in little tufts, filaments erect, minute, closely j^acked, 
 olivaceous; branches Irregular, obtuse, ascending." — 7/«7-y. 
 
 Not a very well marked species. 
 
HASSALLIA. 231 
 
 23. HASSALLIA Berk. 
 
 Char. " Branches increasing by the elongation and division 
 of a single cclU' — Berk. 
 
 The above definition, like that of Scgtonema, embraces only 
 the essential character of the genus, to it, other well marked 
 peculiarities maybe added; such'as the rigidity of the filaments, 
 the branches usually solitary, and the beaded form of the cells. 
 The genus therefore may otherwise be defined thus : — 
 
 Char. Filaments somewhat rigid, of tmequal diameter. 
 Branches usually solitary, formed hy the elongation and 
 division of a single cell. Cells distinctly moniliform, usu- 
 ally in a single series. 
 
 Kiitzlng's genus Sirosyphon is thus specified : it includes 
 but a single species, and cannot be said to fulfil the intention 
 of the genus Hassallia. 
 
 *' Trichomata parenchymatica ex cellulls gellneis in vagina 
 lamellosa, aplce clausa longitudlnaliter striatis, apice in arti- 
 culos epenchymaticos confluentes trauseuntibus compositum. 
 Spermatia iusterstitialia. Rami basi genlculati." 
 
 The above characters seem to me to be only of specific and 
 not generic importance. 
 
 The genus Hassallia was instituted by the Rev. ]\Ir. 
 Berkeley a considerable time ago : that gentleman, however, 
 delayed publishing it, and conceived on the appearance of the 
 " Phycologia Generalis" that it was frustrated by Kutzing's 
 genus Sirosyphon, which I cannot think that it is. 
 
 1. Hassallia ocellata Hass. 
 
 Plate LXVII. Figs. 2. 7. 6. 
 
 Char. Branches solitary, divaricating, slightly contracted at 
 the base. Cells beaded. 
 Conf. ocellata Dillw. t. D. Co7if. ocellata E. B. t. 2530. ; 
 Harvey, In Hook. Brit. Fl. p. 364. Scytonema ocellattnn 
 Harv. in Manual, p. 154. 
 Q 4 
 
232 SCYTONEME^. 
 
 Hab. Springs on the moors near Wolsingham, Durham ; 
 Mr. Backhouse. In a bog on Tower Hill Common, near 
 Southampton : J. JVoods, Esq. West Blanket Island, 
 Kerry : Mr. Andrews. Aberdeen : Dr. Dickie. 
 
 " It is composed of dense tufted masses of a dull brown, 
 except when held against the light, in which position they 
 appear of a horny or dirty orange hue. They are of a rigid 
 substance, and do not adhere to paper in drying. The co- 
 pious branches are irregular, wavy or curved, the ultimate 
 ones blunted, and many of them turned one way. The 
 greatest peculiarity of this species is that a chain-like row 
 of vesicles runs along the centre of the frond, each of which is 
 marked with a central dot, probably consisting of a mass of 
 seeds." — E. B. 
 
 2. Hassallia compacta Hass. 
 
 Plate LXVIII. Fig. 3. 
 
 Char. " Filaments decumhent, branched, densely intericoven 
 into blackish tufts. Branches suberect, dichotomous, and 
 fasciculate within, furnished with transverse rings.''^ — 
 Grev. 
 Scyt. compactum Harv., 1. c. p. 364. ; also in Manual, p. 154. 
 Hab. Moist rocks in the Pentland Hills : 3Iessrs. Ariiott 
 and GrevUle. 
 
 This species, with a specimen of which I have been kindly 
 favoured by Dr. Greville, does not differ very considerably 
 from //. ocellatum, and chiefly in the closer arrangement of 
 the sporidia. I am not certain that it is really distinct. 
 
 3. Hassallia turfosa Hass. 
 
 Char. Frond coriaceous, sparingly branched. Branches siib- 
 erect. Cells annuliform, rarely beaded. Sheath broad. 
 Dematium turfaceum Pers. Myc. Eur. vol. i. p. ^%. ; Lk. 
 Sp. PI. i. 134. ; E. B. 2826. %. 1. 
 
IIASSALLIA. 233 
 
 Hab. On heath, sphagnum, &c., on tlie Pentland Hills, 
 found by Dr. Greville. 
 
 " Formiug a short brownish shaggy stratum, overrunning 
 the plants on which it grows. Threads suberect, giving out 
 in a proliferous manner short, very obtuse, branches of a beau- 
 tiful golden yellow brown. Two sometimes spring from the 
 same point. The walls of the threads are very thick. Spo- 
 rangia annuliform, green, composed of a compact grumous 
 mass, or divided, especially in the older tln*eads, into a single 
 row of distinct oblong granules. 
 
 "This very beautiful Alga was communicated by Dr. 
 Greville to Sir W. J. Hooker, in whose Herbarium it Is 
 marked by M. Klotzsch Dcmatium turfaceum Lk., which 
 there Is every reason to believe is correct. Link appears to 
 have been acquainted with the plant merely from the short 
 notice of It by Persoon in the ' Mycologia Europa^a.' Fries 
 tells us expressly, ' Syst. JNIyc' vol. ii. p. 603. ad not, that it is 
 an Alga. It is indeed a true Scytonema, which bears much rc- 
 &Qm\An.\\Q,Qio Petahncma alatum, though it wants the character- 
 istic feature of that very curious production. Badulum afer- 
 rimum of Fries, of which specimens are published in ' Scleromy- 
 cetes Suecire', and to which Persoon's var. cormitiim is referred, 
 is altogether different, and truly a fungus." — M. J. B. 
 
 This beautiful species bears some resemblance to H. ocel- 
 latum and still more to H. compactum ; the cells, however, 
 are rarely beaded, as they invariably are in both those spe- 
 cies. It is no doubt distinct from cither, the branches are 
 generally single. 
 
 4. HaSSALLIA ? BYSSOIDEA Hass. 
 
 Plate LXVII. Fig. 5. 
 
 Char. Filaments minutp, erect, simple, of equal diameter, fas- 
 ciculate, obtuse, forming an unequal blackish crust. Striaj 
 very close and evident. 
 Scyt. byssoideum Berk., Glean. Alg. t. 19. f. 1. ; Harv. 
 Hook. Brit. Fl p. ii. p. 3GG. ; Harvey, in INIanunl. 
 
234 SCYTONEME^. 
 
 Hub. On the trunk of a living elm at Oundle, North- 
 amptonshire : Rev. M. J. Berkeley. 
 
 I doubt much whether this species be a true Hassallia. 
 It is much more like an Oscillatoria, the filaments being simple, 
 of equal diameter, regularly striated, and very brittle. The 
 only character which seems to vmite it with Scytonema is its 
 erect habit. It might possibly be better placed in Kiitzing's 
 genus Symi-)liosyiilwn : if not, it should perhaps form the type 
 of a new genus. The genus Sy?7iphosypho7i is thus charac- 
 terized. 
 
 " Trichomata erecta vel adscendentia, vagina cartilaginea 
 multistriata (lamellosa) saspe fasciculata, involuta, basi conflu- 
 entes, lateraliter concreta." 
 
 5. Hassallia ? limbata Hass. 
 Plate LXVII. Fig. 6. 
 
 Cka?'. " Filaments thick, jiexuous, ceruginous, loith a broad, 
 ■pellucid margin, loosely intertvovcn in a dense dull aru- 
 ginous green stratum.^'' — Grev. 
 O. limbata Grev. Crypt. Flor. Syn. p. 40. and t. 246. 
 (O. rupestris). Scytonema arugineo-cinereum Kiitzing, 
 Phyc. General, p. 214. Ocellatoria limbata Harv. in 
 Hook. Brit. Flor. p. 375. ; also in Manual p. 164. 
 Jffab. On perpendicular rocks, exposed to the trickling of 
 water, Pentland Hills : Dj% Greville. 
 
 On first examining an authentic specimen of this plant, I 
 was impressed with the idea that it ought to be referred to 
 the genus Scytonema, but from not discovering branches on 
 the filaments, I did not feel quite certain on this point. 
 Kiitzing having made the species the type of his genus Scy- 
 tonema, there can be but little doubt but that it really 
 belongs to the family Scytonemea. " Plant covering the face 
 of the rock for several inches together, and when old, peeling 
 oflf in rather large pieces. Externally it is mostly of a dull 
 and brownish green colour, but within more of a verdigris 
 
SCYTONEMA. 235 
 
 green, differing in intensity in different parts; here and 
 there gelatinous and semi-transparent. Filaments thick for 
 their length, very flcxuous, with a pellucid colourless limb, 
 equal in breadth to the coloured, striated portion, which is of 
 a pale verdigris green." — Grev. 
 
 24. SCYTONEMA J^. 
 
 Char. " Branches increasing hy the protrusio7i and division 
 of the central roxo of cells.''^ — Berk, in lit. 
 Derivation. From aKvro?, a skin, and vrnia, a thread ; in 
 allusion to the toughness of the filaments. 
 
 The genus Scytonema has hitherto evidently embraced the 
 description of plants belonging to two distinct genera. 
 
 The above, therefore, is ]\Ir. Berkeley's definition of the 
 genus Scytonema, as very properly proposed to be restricted 
 by that gentleman a considerable time ago. This concise de- 
 finition briefly describes the essential character of the altered 
 genus, but there are also others which serve to distinguish its 
 species from those which have hitherto been associated with 
 Scytonema, and which confirms the view adopted by INIr. 
 Berkeley of the necessity of forming two genera out of those 
 species. From the protrusion and division of the central 
 row of cells, it follows that the branches should frequently 
 be in j^airs, and this is generally the case : the filaments, 
 also flaccid, of nearly equal diameter, are rarely moniliform. 
 The definition of the reconstructed genus Scytonema might 
 stand more fully thus : — 
 
 Char. Filaments y?acc2W, of nearly equal diameter. Branches 
 usually in pairs, and formed hy the protrusioii and divi- 
 sion of the central row of cells. Cells generally quadran- 
 gidar, rarely if ever regularly moniliform. 
 
 Kiitzing, in his " Phycologia Generalis," has removed one 
 species from the genus Scytonema, S. ocellatum, and formed 
 for it a new genus Sirosyphon ; but still the genus Scyto- 
 nema of Kiitzino; docs not in the most remote degree cor- 
 
236 SCYTONEMEiE. 
 
 respond with the genus as defined by Mr. Berkeley or 
 myself, neither does his genus Siros^/phon answer to the 
 genus Hassallia, formed by Mr. Berkeley for those species 
 hitherto associated with the genus Scytonema, but which the 
 definition of that genus, as it at present stands, does not 
 embrace. 
 
 The following is Kiltzing's definition of Scytonema : — 
 " Trichomata vagina duplici, firma crassiuscula colorata 
 arete inclusa ramosa ; rami ex continuatione trichomatis in- 
 terni et prolongatione vaginae oriundi, non basi iis discreta. 
 Spermatia ex articulis intumescentibus progenita." 
 
 In the genus as thus characterised, Kiitzing includes the 
 following British species. Scytonema (sruginco-cinereum 
 ( Ocellatoria rupestris, Grev. Scot. Flor. Turf. 246. ?), *S'. my- 
 ochrous, S. turfosum, and iS. coinpactiim. Now out of these 
 fovu' species there is but one which could be received into 
 the genus Scytonema of Mr. Berkeley, and that one is Scyt. 
 myoclirous. It is clear, therefore, that there is no correspond- 
 ence between the genus Scytonema of Berkeley and that of 
 Kiitzing. 
 
 1. Scytonema hibernicum Hass. 
 
 Plate LXVIII. Fig. 1. 
 
 Char. Filaments of considerable diameter. Cells about as 
 long as broad, issuing in pairs at rigid angles with the 
 stems. 
 Scyt. hibernicum Hassall, MS. 
 
 Hab. On a clayey bank, co. Antrim, Ireland : il/r. 
 Moore. 
 
 Of this beautiful species I have seen but a single specimen. 
 It was sent to me by INIr. Moore, with the name of Scyt. 
 ocellatwn upon it, with Avhich plant however it has no affi- 
 nity. The cells are of exactly the same form as in Scy. 
 myochrous, from Avhich it differs principally in being alto- 
 gether laro-er. 
 
PETALONEMA. 237 
 
 2. SCYTONEMA MYOCHROUS Ag. 
 
 Plate LXVIIL Fig. 2. 
 
 Char. Filaments of less considerable diameter, eloncjate, mostly 
 decumbent and jlexuous. 
 Lyngb. t. 297. and S. ocellatum Lyngb. t. 28. Conf. 
 myochrous Dilhv. Conf. 1. 19. ; E. B. t. 1555. Conf. mi- 
 rabilis, E. B. 2219. (not of Dilhv.) Scytoncma con- 
 textum Carmichael. 
 
 Hah. Various parts of Wales : Mr. Dillwyn and 3Ir. 
 Woods. Neighbourhood of Bantry : 3Iiss ITutchins. 
 Crowborough Warren, and in Pressbridge Warren, near 
 Wych Cross : Mr. Jenner. Dolgelly : Mr. Ralfs. 
 
 Tills species differs from the previous one only in beino- 
 smaller in all its parts. I have no doubt of the correctness 
 of Scyt. contextiim as a synonym, having, through the kind- 
 ness of IMr. Harvey, had an opportunity of examining an 
 authentic specimen. Carmichael thus describes it: — " Thi- 
 species occurs in a thin, closely matted blackish fleece, of ins 
 determinate extent. Filaments two or three lines in length, 
 simple, or rarely fm'nished with one or two branches," 
 (which are occasionally geminate, as in S. inyochrous), " in- 
 terwoven into an almost inextricable stratum. Sporidia, when 
 visible, which rarely happens, globular and rather distant. 
 Besides the comparative shortness of the filaments, and the 
 more intimate contexture of the stratum, this species differs 
 from 8. myochrous in becoming, when dry, of a light greyish- 
 green colour instead of black." — Carm. 3ISS. 
 
 25. PETALONEMA Berk. 
 
 Char. Frond composed of flat, branched or simple filaments, 
 the margins membranaceous and striate. 
 Derivation. From irsraXov, a leaf or lamina, and vi-jj.La, a 
 thread ; in allusion to the singularly winged filaments. 
 
238 SCYTONEME^. 
 
 1. Petalonema ALATUM. 
 Plate LXVIII. Fig. 6. 
 Char. Filaments broadly memhranaceous. 
 P. alatum Berk., Glean, of Alg., p. 23. t. 7. fig. 2. Oscilla- 
 toria alata Carm. Grev. Ciypt. Fl. 222.; Harv. in 
 Hook. Br. Fl. 378. ; Harv. in Manual, p. 1G8. 
 Hah. On wet calcareous cliffs, Appin : Capt. Carmichael. 
 Oban : Rev. M. J. Berkelei/. Aberdeen : Di: Dickie. 
 
 This biglily curious plant forms a brownish or chestnut- 
 coloured stratum, subgelatinous. The filaments, which are 
 irregularly branched, central, consist of a coloured thread, 
 which is distinctly annulated, and a broad colourless striated 
 sheath, obtuse at its extremity. The contrast between the 
 coloured and uncoloured portions of the filaments, and the 
 delicate stride on the sheath, render this a very beautiful 
 object. 
 
 26. ARTHEONEMA Hass. 
 
 Char. Filaments simjjle, rarely hrayiched ? of equal diameter, 
 divided into successive portions. 
 Derivation. From apOpov, a joint, and vrjixa, a thread. 
 
 It is not without some hesitation that I have ventured to 
 constitute a new genus for the reception of this curious pro- 
 duction, Avhich could not consistently I think be allowed to 
 remain with either Scytonema or Hassallia. 
 
 1. Arthronema cirrhosum Hass. 
 Plate LXVin. Fig. 7. 
 Char. Filaments of considerable size, stricB close and evident. 
 Scytonema cirrhosum Carm. T?//?,? widely spreading, ^/a- 
 ments floating in bundles, spuriously ? branched ; 
 branches beset with fragments towards the top." — 
 Carm. MS. 
 
ARTHRONEMA. 239 
 
 Ilarv. Ill Hook. Br. Flor. p.3G6.; Ilarv. in Manual, p. 155. 
 Hah, Borders of lakes at Lismore Island : Cajitain Car- 
 michael. 
 
 " It occurs in continuous fleeces parallel to the water's 
 edge, of a deep chestnut colour when lying flat, dark olive 
 when floating. The fleeces are made up of small, contiguous 
 fasciculi of interlaced filaments. The filaments are from 
 half an inch to an inch in length, simple or spuriously (?) 
 branched, and prolonged by successive adhesions of portions, 
 seemingly of broken filaments, which at length coalesce and 
 form a knot at the points of adhesion. The transverse strias 
 arc close and conspicuous." — Carm. 
 
 Each filament, at regular distances, is obliquely di^-ided: 
 these divisions are not formed by ^' successive adhesion of 
 portions," but by the partial separation into portions of a 
 single filament, the Investing membrane or sheath remaining 
 entire. 
 
 Section ii. Calothricem. 
 
 " I have seen upon a Cahthrix, gathered in the ponds of 
 water proceeding from the overflowing of the Seine, se- 
 condary oblong branches formed, which at first sight pre- 
 sented no difference of organization with that of the principal 
 tube. These branches presented transverse approximate in- 
 ternal divisions, and were filled with cndochrome of a very 
 pale green tint. Shortly after their appearance, I have seen 
 the contents of these branches pierce the external envelope, 
 which it left empty and transparent, and issue under the 
 form of a tubular body, oblong, partitioned, obtuse at both 
 extremities like the principal filament. Unfortunately I 
 have not been able to follow their devclopement, because the 
 filaments themselves have become destroyed, or covered Avith 
 crystals resembling those of Chatoplwra.^'' — P. 333. 
 
 Mr. Dillwyn, in his " Introduction to the British Con- 
 fervte," makes some remarks of the same nature in refer- 
 ence to C. distorfa. 
 
240 SCYTONEME^. 
 
 27. TOLYPOTHPvIX Kutzing. 
 
 Char. Filaments of nearly equal diameter, tufted, tenacious. 
 Branches few, continuous with the main filaments, an- 
 nulated at the base. Cells indistinct, rarely moniliform. 
 Sporules escaping at the extremities of the filaments. 
 Derivation. From ToKvirrj, loool, and OpL^, hair. 
 
 Kutzing, in his " Phycologia Generalis," has established 
 the genus Tolypothrix, which I here adopt. In the genus Ca- 
 lothrix Ag. Kutzing describes only C. mirahilis, a production 
 which differs essentially and generically from the j)roper 
 Calothrices, all of which Kiltzing refers to his new genus. 
 A preferable arrangement I conceive would have been to 
 have constituted a new genus for the single species C. mira- 
 hilis, and to have allowed the Calothrices to have remained in 
 the genus in which they have been so long placed, and the 
 nature of Avhich is so well understood by algologists. 
 
 a. Branches discrete. 
 
 1. Tolypothrix punctata Hass. 
 
 Plate LXIX. Fig. 3. 
 
 Char. Filaments someiohat irregular, very sparingly branched, 
 diameter considerable. Cells not quite so long as broad, 
 nucleated. 
 
 Hob. Under a cascade, co. Wicklow : ISIr. Moore. 
 
 This species is larger than T. distorta, and the filaments 
 less uniform ; tlie branches are rarely formed, and the cells 
 punctated. 
 
 2. Tolypothrix distorta Ki'itz. 
 
 Plate LXIX. Fig. 4. 
 
 Char. Filaments elongated, bluish green, forming large tufts, 
 
 mucous, someiohat rigid, branched. Branches erect,flexuous. 
 
 Conf. distorta Dillw. t. 22. ; E. Bot. t. 2577. C. distorta 
 
 Harv. in Hook. Brit. Flor. p. 369. ; Harv. in iMnnual, 
 
 p. 158. 
 
TOLYPOTHRIX. 241 
 
 Hab. . Adhering to sticks, stems, &c. ; common. 
 
 This species forms tufts of from half an inch to an inch in 
 height, of a dark green hue, which on drying becomes of an 
 intense verdigris or blue green colour ; the filaments are slen- 
 der, and the branches elongated and simple. 
 
 3. ToLYPOTHRix Berkeleyana Cami. 
 
 Plate LXIX. Fig. 5. ? 
 
 Char. Filaments minute, bright grass green, Jiaccid, Jiexuous, 
 tufted. — Harv. 
 Calothrix Berkeleyana Harv. in Hook. Br. Fl. p. 367. ; also 
 in Manual, p. 157. 
 
 " Tufts scattered, about a line in diameter, of a vivid 
 green colour. Filaments twenty to thirty in each tuft, ra- 
 diating horizontally from a central point, exceedingly slender, 
 flaccid, tapering to a hyaline point, variously curved or flex- 
 uous. It conies very near C. confervicola ; but the filaments 
 are much shorter and more slender, and possess nothing of 
 the rigid, erect habit of that species." — Carm. MS. cum 
 icone. 
 
 4. ToLYPOTHRIX NIVEA TIass. 
 
 Plate LXIX. Fig. 6. 
 
 Char. " Filaments exceedingly slender, rigid, lohite, forming 
 dirty yellow continuous tufts.'" — Harv. 
 Conf. Jiivea Dillw. t. C. ; E. Bot. 2529. Cal. nivea Harv. 
 
 in Hook. Brit. FI. ; also in Manual, p. 157. 
 Hab. In sulphur springs, Yorkshire and Durliam : Dr. 
 Willan. Near Darlington: Mr. TV. Backhouse. Plentiful 
 in sulphur springs, Llanwrtyd, and other similar springs 
 in Great Britain : Dillw. 
 
 " Dr. Willan assures us that this species is found below 
 the spring no further tlian as the water retains the sensible 
 
 R 
 
242 SCYTONEMEiE. 
 
 sulphureous properties, as if the hepatic gas were necessary 
 to its production and nourishment." — Dillw. 
 
 5. TOLYPOTHRIX RUFESCENS. 
 
 Plate LXIX. Fig. 7. 
 
 Cha?'. Filaments minute, spreading in a thin slimy purplish 
 stratum. 
 Calothrix rufescens Carm.; Harv. in Hook. B. Flor. p. 368.; 
 
 Harv. in Manual, p. 158. 
 Hab. On rocks under the spray of cascades, Appin: Cap- 
 tain Carmichael. 
 
 " Crust or stratum of indefinite extent, and so thin as to 
 seem a mere discoloration of the rocks until the finger is 
 passed over it, when a certain sliminess detects the presence 
 of the plant. Filaments half a line in length, and so slender 
 as to appear mere lines under the highest jjower of the com- 
 pound microscope." — Carm. 3IS. 
 
 b. Branches adherent to the main filaments. 
 6. ToLYPOTHRIX DlLLW^YNII Hass. 
 
 Plate LXVIII. Figs. 4, 5. 
 
 Char. Filaments tufted. Branches subulate, adherent to the 
 principal threads nearly their ichole length. Striae about 
 a diameter from each other. 
 
 Scytonema Dillioynii Harv. et Ralfs' MS. 
 
 Hab. Dolgelly : Mr. Ralfs. Moist rocks, co. Antrim : 
 Mr. Bloore. 
 
 This species was named by Harvey Scytonema Dillwynii, 
 under the impression that it was the Microcoleus ? Dillwynii 
 of his "INIauual," and the Conf vaginata of Dillwyu, t. 99. 
 which it is difficult to conceive from Dillwyn's description 
 that it really is. I felt much inclined to place this plant by 
 
CALOTHRIX. 243 
 
 itself In a distinct genus, and perhaps this would have been 
 the correct course ; It Is, however, more naturally associated 
 with the genus Tolypothrix than with Scytonema. It forms 
 little tufts two or tlu'ee lines in height. 
 
 28. CALOTHRIX. 
 
 Char, Filaments of equal diameter , branched by apposition. 
 Derivation. From koXos, beautifid, and 6pi^, a hair. 
 
 1. CALOTHRIX MIKABILIS. 
 
 Plate LXIX. Fig. 1. 
 
 Char. FUaments tufted, aruginous, black, articulated. Stria? 
 distant about the half of a diameter from each other, dis- 
 tinct. 
 
 Conf. mirabilis DIllw. t. 96. Calothrix atroviridis Harv. 
 in Manual, p. 159. ; Harv. in Hook. B. Flora, p. 369. 
 
 Ilab. On mosses and in small streams, rare. Stream 
 which runs through the wood at Penllegare, near 
 Swansea: Dilhcyn. — C. atrovii'idis in spring wells, near 
 Penzance : Mr. Ralfs. Aberdeen : Dr. Dickie. 
 
 Having had oiDportunltles of examining, through the kind- 
 ness of Mr. DHlwyn and Mr. Harvey, authentic specimens of 
 Conf mirabilis and Calothrix atroviridis, I have no hesita- 
 tion in declaring that the two plants are identical. There 
 is a close resemblance between C. mirabilis and Lyncjbya 
 copulata, which species ought not to be far removed from each 
 other in a natural arrano-ement. 
 
 R 2 
 
244 
 
 Fam. XIII. OSCILLATORE^. 
 
 The family of Oscillatorece, limited to the genera Oscillatoria 
 and Microcoleus, is one of the most distinct and remark- 
 able of the dl\dsions of the Alg<z. The majority of the 
 species are characterized by the minuteness of their fila- 
 ments, the equality of their calibre, and their mathematical 
 rectitude or straightness ; they are still further distinguished by 
 the brevity of their cells, the ease with which these sei:)arate 
 from each other, the wonderful rapidity of their growth, the 
 sm-passing brilliancy of their colours, and lastly, by a peculiar 
 oscillation, upon which feature their generic name has been 
 founded, but with regard to which I can myself perceive 
 nothing extraordinary, although the phenomenon is certainly 
 peculiar to this family — nothing indicative, as most suppose, 
 of a sensitive or animal life. The explanation to be given 
 of this oscillation of the filaments I consider to be partly of 
 an external, and entirely of a physical character. It has been 
 stated that the filaments of very many species of Oscillatoria, 
 and indeed of all those which present the phenomenon of 
 oscillation, are remarkable for their straightness or rectitude, 
 w^hich is due to a certain degree of elasticity belonging to 
 them, and which leads to the eftbrt on their part, whenever, 
 as on being placed for observation on the field of the micro- 
 scope, must be the case, they are bent or put out of a straight 
 line, to recover that position which is natural to them. This 
 elastic property of the filaments, currents almost impercep- 
 tible in the liquid in which they are immersed, and perhaps 
 unequal attractions amongst the filaments themselves, are 
 causes amply sufficient to explain any motion which I have 
 ever witnessed amongst the Oscillatoria, and which motion I 
 cannot help thinking to have been misunderstood and exag- 
 gerated to such an extent, as to throw around these plants an 
 unnecessary degree of mystery. 
 
OSCILLATORIA. 245 
 
 Upon the reproduction of this family, and some others 
 which follow, no very precise observations appear to have 
 been made. Vaucher remarking the ease with which the cells 
 or " rings " separated from each other, supposed them to be 
 multiplied by means of these. This separation, however, is 
 probably merely to be regarded as a preparatory step, the 
 true reproduction being by means of zoospores. 
 
 Gerod Chantrans * makes some observations upon the re- 
 production of the OscillaforicB. He states that when an 
 Oscillatoria has reached its complete developement, it emits 
 from its cells a granulated powder, each grain of which 
 increases insensibly until finally it becomes developed Into 
 a perfect plant. In this account, Gerod Chantrans has not 
 swerved far from the truth. 
 
 The species of this family are found under very different 
 circumstances ; upon the moist earth, in stagnant, still, and 
 running waters; in medicinal waters, and in such as are 
 absolutely hot and almost boiling. They are, with very few 
 exceptions, highly mucous to the touch, and in some kinds 
 the filaments are imbedded in a mucous nidus. 
 
 The brilliancy of their colours has been noticed. The 
 tints are various, shades of bright and beautiful greens, many 
 presenting a metallic or a;rugIuous cast, of violet, purple, 
 dark brown and glossy black. 
 
 No descnptlon of a species can be considered perfect, un- 
 less it be taken from an examination of sj^eclmens, both in 
 the recent and dried state, the characters not being identical 
 in these conditions. 
 
 A monograj)h on this family, the result of two or three 
 years' patient and careful observation, is much needed. 
 
 29. OSCILLATORIA. 
 
 Char. Filaments simple, even, elastic, closely striated, and often 
 lying in a 7}iucous matrix. 
 
 Derivation. From oscillo, to vibrate. 
 
 * Reclierches Cliiiniques et IMicroscopiqucs &ur les Confervcs, &c. 
 Paris, an x. 
 
 R 3 
 
246 OSCILLATORE^. 
 
 Kiitzing's definition is as follows : — 
 
 *' Trichomata libera, basi vaginata, ex vagina longe prore- 
 pentla, vaglnje achromaticje tenerrimte, simplices. utrimque 
 opertas llberae, nunquam coalltfe." 
 
 Kiitzing makes a genus for the reception of the Oscillatoria 
 autumnalis Ag., of which Conf. decorticans of Dillw. Is a 
 synonym. The genus is as follows : — 
 
 Phormidium. 
 
 *' Trichomata libera, basi vaginata, ex vagina prorepentia, 
 vaginae achromaticae, sunplices (non lameUosaj), apertai, latera- 
 liter in membranam plus minus ve continuam coalitaB." 
 
 I can offer no opinion on this genus, but I cannot perceive 
 in what the Conf. decorticans (Dillwyn) differs generlcally 
 from other Oscillatorice. 
 
 a. Filaments brittle. 
 
 1. Oscillatoria limosa Ag. 
 
 Plate LXXI. Fig. 2. 
 
 Char. Filaments brittle, straight, large. Stratum 7'ich dark 
 green, glossy, and gelatinous. Strl» strongly marked and 
 close. 
 O. limosa Harv. Hook. Br. Fl. p. 374. ; Harv. Manual, 
 p. 162. (Not of Grev. Flor. Edln. p. 303. ; or Hook. 
 Scot. Fl. part ii. p. 79.) 
 
 Stratum of a rich dark and jeruginous green colour, send- 
 ing out from its edges long radii equally or in bundles ; It is 
 also glossy, even in the dried state. Filaments when recent 
 of equal diameter, but in the dried condition they are seen to 
 be variously twisted and furrowed, and the striae to be much 
 less conspicuous. The furrowing and consequent irregularity 
 of diameter of the filaments in dried specimens, affords not 
 unfrequently a distinguishing character between nearly allied 
 species. Mr. Harvey remarks that this fine species Is ap- 
 parently alluded to by Dillwyn in his description of Conferva 
 
OSCILLATORIA. 247 
 
 fontinalis, t. 64. ; but the figure is more like O nigra. In 
 drying it adheres closely to paper. From O. major it differs 
 in the much greater diameter of its filaments, and darker 
 colour. It is therefore intermediate between these species. 
 
 2. OsCILLATORIA MUCOSA Hass. 
 
 Plate LXXL Fig. 1. 
 
 Char. Stratum gelatinous, dark, aruginous green, glossy. 
 Filaments large. Strife suhdistant. 
 Hah. Floating in a pond like a little dusky cloud; 
 Stevenston : Rev. D. Landshorongh. 
 
 This species agrees with the previous one in all its characters, 
 save in the arrangement of the stri36. The filaments are of 
 the same diameter, of the same gelatinous habit, and present 
 the irregular and furroAved appearance when dried of O. 
 limosa : the only difference between the two species is in the 
 stria3, which are twice as distant in this as in O. limosa. 
 
 The only specimen which I have seen of this species is 
 that sent me by the Eev. D. Landsborough. There can be 
 no doubt entertained of its distinctness. 
 
 3. OsCILLATORIA CINEREA HasS. 
 
 Plate LXX. Fig. 4. 
 
 Char. Stratum of a dull aruginous green colour. Filaments 
 large. Striaj close, very evident. 
 Hah. In a pond on Stanstead Common, Essex. 
 
 This is a fine and well-marked species. The diameter of 
 the filaments is equal to that of the two preceding Oscilla- 
 torice, but they are infinitely less mucous, and the stratum 
 when dried is not in the least glossy, neither do the filaments 
 collapse or become wrinkled in drying, but preserve the same 
 equal diameter in the dried as in the recent state. The 
 species, judging from Carmichael's description, seems to 
 come near to the O&cillatoria littoralis of that observer. 
 H 4 
 
248 OSCILLATORE^. 
 
 4. OSCILLATOKIA TENUIS Ag. 
 
 Plate LXXIL Fig. 1. 
 
 Char. Stratum i-ich dark green, very thitiy gelatinous, with 
 short rays. Filaments pale green, straight. Striae sub- 
 distant, evident. 
 
 Grev. Edin., p. 303. ; Harv. in Hook. Brit. Flor. 374. ; 
 Harv. in Manual, p. 163. O. limosa Hook. Scot. ii. 
 p. 79. Conf. limosa Dillw. t. 20. O. viridis Jolmst. 
 Berw. Flor. p. 264. 
 
 Hab. Common in ditches. 
 
 " In muddy ditches, at first resting at the bottom, but gra- 
 dually rising in bullated strata to the surface, common; stratum 
 extensive, glossy when dry, in which state it fully preserves 
 its colour. Filaments, of half the diameter of those of O. li- 
 mosa, pale green ; strife distant and indistinct. It adheres 
 strongly to paper." — Harv. The stratum of this species 
 exactly resembles that of O. limosa, and the filaments, like it 
 also, contract somewhat in drying ; they are, hoAvever, two 
 or three times smaller ; the stria3 more distant, and not so 
 strongly marked. 
 
 5. OSCILLATORIA CYANEA Ag. 
 
 Char. " Glaucous blue. Filaments simple, entangled, cylin- 
 drical, even, with a deciduous coat. Joints obsolete, about 
 as long as broad." — Sm. 
 Harv. Hook. Br. Fl. p. 374. Conferva cyanea, E. B. 
 
 t. 2578. ; Harv. Manual, p. 163. 
 Hah. Damp walls on the inside of several Suffolk churches ; 
 at Icklingham and Hengrave ; also in Lincolnshire : Sir 
 Thomas Gage, Bart. 
 
 " On the wall it is conspicuous for its light sky-blue colour, 
 like some sort of mucor. Under a high magnifier, and 
 when moistened, it is found to consist of minute, even, simple, 
 entangled threads, one five hundredth part of an inch in dia- 
 
OSCILLATORIA. 249 
 
 meter, coated with a frequently interrupted covering of a 
 dull glaucous green hue, under which the thread itself ap- 
 pears of a lighter glaucous bluish colour, very even in thick- 
 ness and surface, consisting of scarcely distinguishable joints, 
 about as broad as they are long." — Sm. 
 
 6. OSCILLATORIA iERUGESCENS Drum. 
 
 Plate LXXIL Fig. 2. 
 
 Char. Stratum o/" a ^?ze deep green, highly gelatinous ; xohen 
 dried, ceruginous blue, and glossy. Filaments slender, 
 opaque green. Stria3 evident. 
 Druramond, in Ann. Nat. Hist. vol. i. p. 1 . ; Manual of 
 
 Brit. Alg. p. 163. 
 Hab. Lakes of Glaslough, co. Monaghan, Ireland: Dr. 
 Drummond. Farnham : Mr. Jenner. Bottom of pools 
 near Stocket, Aberdeen : Dr. Dickie. 
 
 " Filaments exceedingly slender, opaque green ; conglom- 
 erated in large toughisli glutinous masses, in sheltered, calm 
 situations, and rarely floating on the surface ; in more open 
 exposures, broken into innumerable fragments, and suspended 
 like cloudy flocculi in the water. Stri<z numerous, at dis- 
 tances of about half a diameter from each other. Oscillatory 
 movement often lively. Colour when di'ied, a beautiful 
 a3ruginous blue ; adheres strongly to paper, exhibiting a glossy 
 surface. Filaments expanded by moisture so as to seem re- 
 cent, and sometimes resuming the oscillatoiy motion." — 
 Dr. Drummond. 
 
 This species may at once be distinguished when dried from 
 all others by the peculiarly dense and waxen appearance of 
 the stratum, which also exhibits numerous fissures. The fila- 
 ments are smaller than those of O. tenuis, and the stria; closer. 
 They are likewise brittle, and when dried break up into very 
 short pieces, which arc not of uniform diameter. 
 
250 OSCILLATOREiE. 
 
 7. OSCILLATOEIiL PULCHELLA Hass. 
 
 Plate LXX. Fig. 5. 
 
 Char. Filaments thick, straight, brittle, vivid green. Stria 
 closBi very conspicuous. 
 Hah. Bottom of pools near Stocket, Aberdeen: Dr. 
 Dickie. Cheshunt : A. H. H. 
 
 The filaments of this fine species are more robnst than those 
 of O, virescens and the strias closer. The only other described 
 species with which it could be confounded is O. spadicea, 
 which it resembles in the closeness and strength of the strias ; 
 but the filaments in O. pulchella are rather finer and much 
 more brittle. 
 
 8. OSCILLATORIA VIRESCENS Hass. 
 
 Plate LXXI. Fig. 9. 
 
 Char. Stratum terrestrial, of a light ceruginous green colour. 
 Filaments of considerable diameter, pale yelloivish green 
 straight, brittle. Strise subdistant. 
 Hah. Cheshunt, Herts : A. H. H. Between Eiver Head 
 and Chipstead, bankside : Mr. Jenner. 
 
 This would appear to be a distinct as well as a fine species. 
 The filaments are longer than those of O. tenuis, and more- 
 over preserve their diameter in drying. Stride nearly a dia- 
 meter of the filaments apart, conspicuous. 
 
 9. OSCILLATORIA THERMALIS Hass. 
 
 Plate LXXII. Fig. 3. 
 
 Char. Filaments small, green. Stria) straight, brittle, sub- 
 distant, very evident. 
 
 Hab. In a stream of hot water, Stevenston : Rev. D. 
 La ndsboro ugh . 
 
 The filaments of this species are as slender as those of O. 
 
OSCILLATORIA. 251 
 
 terehriformis, but of a clifFerent colovir, and the striaj are much 
 more evident. 
 
 10. OSCILLATORIA SPLENDIDA Grev. 
 
 Plate LXXII. Fig. 8. 
 
 Char. Stratum bright (sruginous or bluish green, thin, with 
 
 short rags. Filaments arachnoid, straight or curved, 
 
 Strias wholly invisible. 
 Grev. Flor. Edin., p. 304. ; Harv. Br. Flor. 375. ; Harv. 
 
 Manual, p. 164. O. membranacea^ O. amphibia and 
 
 O. elegans Ag. 
 Hah. In tubs of water in the stove of the Botanic Garden, 
 
 Edinburgh: Dr. Greville. 
 
 This is the most slender of all the Oscillatorice. The 
 stratum exactly resembles in colour and appearance that of 
 either O. limosa or O. tenuis, from Avhich it may be imme- 
 diately detected by the microscope. Agardh has described 
 this species under no less than three different names, as I 
 have ascertained from an examination of authentic specimens 
 in the Herbarium of Sir W. J. Hooker. 
 
 11. OSCILLATORIA AUTUMNALIS J<7. 
 
 Plate LXXII. Fig. 7. 
 
 Char. Stratum of a deep (Eruginous green, with a metallic 
 lustre, very lubricous. Filaments very slender. Stria? 
 subdistant. 
 O. autumnalis Ag. Syst. p. 62. ; Grev. Flor. Edin. p. 305.; 
 
 Harv. I.e. p, 376.; Harv. Manual, p. 165. 
 Hob. Appin : Carmichacl. 
 
 The filaments of this species are very slender, not being 
 more than twice the diameter of those of O. splcndida. They 
 cohere closely, and are usually very much broken when ex- 
 amined under the microscope. Strlaj not very evident, sub- 
 distant. 
 
252 OSCILLATORE^. 
 
 12. OSCILLATORIA MUSCOEUM Aff. 
 
 Plate LXXII. Fig. 12. 
 
 Char. Stratum da7'k (Bruginou& greeny shortly radiating, creep- 
 ing over mosses. Filaments thickish, pale blue green. 
 Stria3 distant. 
 
 O. muscorum Ag. Syst. p. 375.; Harv. Hook. Br. Flor. 
 
 365.; Mamial, p. 164. 
 Hab. On Hypnum ruscifolium in rapid streams : Captain 
 
 Carmichael. 
 
 " Stratum three or four inches in extent, closely inter- 
 Avoven with the branches and leayes of mosses, of a bluish 
 green colour, and slightly lubricous. Filaments a line or two 
 in length, variously curved, and radiating. Striaj at the 
 distance of a diameter from each other." — Carm. MS. Fila- 
 ments brittle, about equal in diameter to those of O. turfosa, 
 and when examined in the dried state, usually found to be 
 much broken up, with the strire all but invisible. 
 
 b. 'EWscmQXiis Jlexuous, coriaceous. 
 13. OSCILLATORIA CORIUM Ag. 
 
 Char. " Stratum thick, siibcoriaceous, opaque, dull broivnish, 
 streaked tvith pale green. Filaments yellowish, slejidcr. 
 Striaj indistinct, dista^it.''^ — Harv. 
 O. corium Grev. Flor. Edin., p. 303. ; Harv. Hook. Br. Fl. 
 
 p. 377.; Harv. Manual, p. 166. 
 Hab. On the rocky bottoms of aliDine rivulets. 
 
 " Stratum thick, tough, dull brownish ; occasionally 
 streaked with pale green, which in some varieties is the pre- 
 vailing colour, slightly glossy Avhen dry; filaments slender. 
 In some situations it radiates in fascicles from its whole upper 
 surface ; in otliers, it is found ahnost denuded of radii, and 
 forming a compact leathery stratum." — Harv. 
 
OSCILLATORIA. 253 
 
 14. OSCTLLATORIA TURFOSA Carm. 
 
 Plate LXXII. Fig. 6. 
 
 Char. Stratum pale verdigris green, glaucous, with an oclira- 
 ceous substratum. Filaments slender, curved. Striaj 
 distant. 
 O. turfosa Harv. in Hook. Br. Flor. ; Ilarv. in Manual. 
 Hal. On floating sods in old turf pits. Appin : Capt. 
 Carmichael. Near Dolgclley : Mr. Ralfs. 
 
 " This species grows in a tliick intensely green layer, over a 
 tough slimy ochre-coloured substratum. It entirely enveloped 
 the sods, some of which were a foot and a half in diameter. 
 Filaments veiy slender, more or less curved, and mostly hya- 
 line at the point." — Carm. 3IS. The filaments are nearly 
 equal in size to those of O. muscorum, from wliich, however, 
 they may l)e distinguished by their greater tenacity and 
 ■length. Sometimes the endoclurome is discharged from a 
 portion of a filament. 
 
 15. OSCILLATORIA SUBFUSCA Vauch. 
 
 Plate LXXII. Fig. 9. 
 
 Char. Stratum dull greyish brown, somewhat streaked zvith 
 green; soft, green, fragile. Filaments verg slender. 
 Stria? inconspicuous. 
 0. suhfusca Vauch. Hist, des Conf. ; Lyngb., t. 2G. ; 
 Harv. in Br. Flor. 377. ; Harv. in Manual, p. 16G. . 
 
 ' Hah. Rocks and stones in sub-alpine rivulets. 
 
 Stratum " soft, slimy, void of tenacity, wrinkled ; of a 
 dusky grey colour." — Carm. It diflfers from O. corium 
 " chiefly in being more gelatinous and fragile." — Harv. 
 The filaments are very slender, long, much curved. Striaj 
 in the dried specimens Avholly invisible. 
 
254 OSCILLATORE^. 
 
 16. OSCILLATORIA VIOLACEA Johnst. 
 
 Plate LXXII. Fig. 10. 
 
 Char, " Mass gelatinous, dark purple. Filaments very 
 slender, straight, without perceptible, transverse strice, laid 
 on a thill, compact, greenish substratum.''^ — Johnston. 
 
 O. violacea Johnston, Berw. Fl. p. 264. ; Harv. in Hook. 
 Br. Flor. p. 377. ; Harv. in Manual, p. 166. Oscillatoria 
 rubiginosa Carmichael, MS. 
 
 Hab. Rapid streams near Berwick upon Tweed: Dr. 
 Johnston. On stones in the bottoms of rivers, co. An- 
 trim : D. Bloore. Appin : Capt. Carmichael. 
 
 "Wlien dry, the filaments of tliis species assume a blackish 
 green cast, with an evident gloss. The filaments are thicker 
 than those of O. subfusca, but do not, like those of that spe- 
 cies, preserve their calibre in drying : they are also more 
 brittle. Stria? in the dried specimens almost invisible, at a 
 distance usually of about two diameters from each other. 
 Dr. Johnston considers this to be the " Conferva mucosa con- 
 fragosa rivulis innascens " of Dlllenius. 
 
 17. Oscillatoria rupestris Ag. 
 Plate LXXII. Fig. 11. 
 
 Char. Stratum blackish green, thick, opaque, extremely tough. 
 
 Filaments ligid, brittle. Stri» almost imperceptible, at 
 
 distances of about half a diameter. 
 Ag. Syst. p. 63. ; Harv. Hook. Brit. Fl. p. 377. ; Harv. in 
 
 Manual, p. 166. O. tenax Carm. MS. 
 Hab. On the precipitous face of cascades. Appin : Capt. 
 
 Carmichael. 
 
 " Stratum extensive, slimy, remarkably tough and elastic, 
 black on the surface, ash-coloured underneath: when dry 
 blackish green. Filaments pale green, straight, or variously 
 curved, radiating, but not equally in all directions." — Carm. 
 MS. The dried stratum of this species resembles in colour 
 
OSCILLATORTA. 255 
 
 that of O. muscorum, than which, however, it is much more 
 tough and clastic : the filaments likewise are much smaller. 
 They are intermediate in diameter between those of O. suh- 
 fiisca, and O. violacea, differing also from both in some other 
 respects. They are more brittle than those of O. suhfusca, 
 though like those of that species they preserve their diameter 
 in drying, which is not the case with O. violacea. The striaj 
 are close, and tolerably evident. 
 
 18. OSCILLATORIA SPADICEA Carm. 
 
 Plate LXXI. Fig. 5. and Plate LXXII. Fig. 5. 
 Char. Stratum very thin, spreading. Filaments yellowish 
 brown, thick, variously curved a7id ttvisted. Strias con- 
 spicuous, and very close. 
 O. spadicea Harv. Hook. Brit. Fl. p. 378. ; Harv. in 
 
 Manual, p. 167. 
 Hah. On damp mossy earth ; rare. Appin : Capt. Carmi- 
 
 chael. Ireland : Mr. Moore. Cheshunt : A. H. 11. 
 " It occurs in a very thin dark green stratum, spreading to 
 the extent of several feet, and is hardly to be distinguished 
 from the mossy earth on which it grows. Filaments short, 
 straight, curved, or spirally twisted, radiating in all directions, 
 and possessed of all the movements peculiar to the tribe." — 
 Carm. 
 
 c. Stratum blackish ; filaments brittle, not coriaceous. 
 19. OSCILLATORIA NIGRA Vauch. 
 
 Plate LXXI. Fig. 3. 
 Char. Stratum black ; ichen dry bluish black, tvith long radii. 
 Filaments 2^(^^<^ bluish green, thick. Strife very distinct 
 and close. 
 Hook. Scot. ii. p. 79. Co?if. fontinalis Dillw. t. 64. 
 O. limosa, Grev. Edin. p. 303. O. nigra Harv. in 
 Manual, p. 165. 
 
256 OSCILLATOREJE. 
 
 ' Hah. Ditches and ponds ; common. 
 
 " Stratum extensive, blackish, with a shade of green ; when 
 dry, blue black, very rapid in its growth and sending out 
 long vividly oscillating rays. Dillwyn's figure of Conferva 
 fontinalis answers to this species pretty correctly." — Ilarv. 
 
 20. OSCILLATORIA CONTEXTA Carm. 
 
 Plate LXXL Figs. 7. 4. 6. 
 
 Char. Stratum glossy black, strongly striated. Filaments 
 someiohat thick, pale green. Stria3 subdistant, evident. 
 O. contexta Harv. Hook. Brit. Fl. p. 376.; Manual, p. 165. 
 Hah. On moist ground. Appin: Capt. Carmichael. 
 Cheshunt : A. H. H. Sussex : Mr. Jenner. 
 
 " Stratum of indefinite exteiit, three feet and upwards, 
 exceedingly thin, and peeling off in large flakes in dry 
 weather, of a deep but shining black colour, scored or striated 
 in all directions. These striaj are caused by thick fasciculi of 
 filaments, shooting out either parallel to or across each other, 
 changing their course from time to time, and sending off la- 
 teral fasciculi. The filaments are rather thick, about a line in 
 length, straight, or variously curved, of a greyish green colour, 
 and they radiate with great rapidity. A portion of the stra- 
 tum, not more than a line in diameter, placed in a Ayatch-glass 
 filled with water, overspread the whole area of the glass wnth 
 filaments in the course of a night."' — Carm. BIS. This is 
 a very distinct as well as fine species. The gloss of the stra- 
 tum is equal to that of satin, and the filaments are in calibre 
 not less than those of O. tennis, from which species it is dis- 
 tinguished chiefly by its colour. The filaments do not con- 
 tract in drying. 
 
 21. OSCILLATORIA CaeMICHAELI Hass. 
 
 Plate LXXL Fig. 8. 
 Char. Stratum black, destitute of gloss, thin, brittle. Fila- 
 
OSCILLATORI-A. 257 
 
 ments slender, straight, brittle. Striae suhdistant, scarcely 
 perceptible. 
 
 O. nigra Carmichael, MS, 
 
 This species differs only from tlie following iji the absence 
 of gloss on the filaments ; a diiference which is, in all pro- 
 bability, of specific importance. 
 
 22. OSCILLATORIA TEREBRIFORMIS Ag. 
 
 Plate LXXII, Fig. 4. 
 
 Char. Stratum terrestrial, bluish black, glossy. Filaments 
 slender, straight, brittle. Strije scarcely evident. 
 O. terebriformis Ag. 
 
 Hab. INIarshy places, Aberdeen, JSTov. 1839 : Dr. Dickie. 
 Sussex : Mr. Jenner. Notting Hill : A. H. H. 
 
 A very abundant species. 
 
 23. OSCILLATORIA DECORTICANS Grcv. 
 
 Plate LXXI. Fig. 10. 
 
 Char. " Stratum smooth, glaucous green, membranaceous. 
 
 Filaments very sle?ider, curved, pale bluish green. Striaj 
 
 distant^ — Harv. 
 Grev. Flom Edin. p. 304. C. decorticans Dillw. t. 26. ; 
 
 Ilarv. Manual, 164. 
 /S corticola. — Stratum blackish green. See PI. LXXI. fig. 4. 
 
 O. corticola Carm. MS. 
 Hab. Damp Avails, rotten timber, often on pumps, &c. 
 
 Common. — /3 "on the trunk of an old sycamore where 
 
 the rain water trickled down : " Capt. Carmichael. 
 
 Stratum membranaceous, not very gelatinous, peeling off in 
 large flakes, and imperfectly adhering to paper ; filaments very 
 minute. I strongly suspect that the O. contexta of Carmi- 
 chael is identical with Greville's O. decorticans, the /3 variety 
 is altosjether different. 
 
258 OSCILLATORE^. 
 
 cl. Filaments brown, brittle, not coriaceous. 
 24. OSCILLATORIA DiCKIEI Hass. 
 
 Plate LXXII. Fig. 13. 
 
 Char. Stratum light chestnut, gelatinous, glossy, Filaraeuts 
 long, straight, brittle, rather thick. Striae visible, sub- 
 distant. 
 Ilab. Pools of fresh water near the sea, Aberdeen : Dr. 
 
 Dickie. 
 The colour of this species is so peculiar as at once to dis- 
 tinguish it from all others which have been described. This 
 colour is preserved in drying ; the filaments are of nearly the 
 same diameter with those of 0. tenuis, but they preserve their 
 calibre when dried. Several fine specimens of this plant 
 were sent me by Dr. Dickie, and which have undergone no 
 change since they have been in my possession, now some 
 weeks. 
 
 e. Filaments collected into close erect tufts. 
 
 In the species of this division of the genus there would 
 appear to be an evident transition to Rivularia, the filaments 
 in one, O. lucifuga, and perhaps in the others, being subulate, 
 and which circumstance induced me, as well as its erect 
 habit, to place that species in the genus Rivularia. I am now 
 satisfied that it should either remain in the division of the 
 genus Oscillatoria in which it has been placed by Mr. 
 Harvey ; or that Kutzing's Symploea ought to be adopted for 
 the reception of the species of tliis division of Oscillatoria. 
 Kiitzing thus defines the genus : 
 
 Trichomata adscendentia vaginata in fasciculos erectos, basi 
 confluentes, coalita ; vaginte ex membrana simplicima, hyalina, 
 (nee striatEe nee lamelloste) formats}. 
 
 25. Oscillatoria Feiesii Ag. 
 
 Char. Stratum bright green, bristling with the elongated, erect, 
 tooth-like fascicles of filaments. 
 
OSCILLATORIA. 259 
 
 Scytonema Bangii Lyngb. Dan. t. 28. Oscillatoria Bangii 
 Carra. MS.; Grev. Ediu. p. 303. O. Fricsii Ilarv. 
 Hook. Brit. Fl. 373.; Harv. in Manual, 162. 
 
 Hah. On mosses in shady subalpinc situations, near Edin- 
 burgh : Dr. Greville. Appin : Capt. Carmichael. Kil- 
 larney : W. H. Harvey. Co. Kerry : Mr. Andreios. 
 
 " Stratum two or three inches broad, bright jeruginous 
 green. Filaments closely interwoven into erect, elongated, 
 tooth-like fascicles, an inch or more in height, pale green; 
 under the microscope annulated Avithin, with a broad limb or 
 border. Well marked by its erect spinulose habit." — Harv 
 The filaments in the dried state are flaccid, long, and apparently 
 of equal diameter. Strife scarcely conspicuous, rather close. 
 
 26. Oscillatoria lucifuga Harv. 
 
 Plate LXV. Figs. 5, 6. 
 Char. Stratum blackish green, bristling icith minnte tooth- 
 like fascicles of filaments. Filaments subulate. 
 
 Colothrix lucifuga Carm. T^ISS. ; Harv. Hook, Br. Flor. 
 p. 373. ; Harv. Manual, p. 162. 
 
 Hab. " On the decayed trunk of an alder, lying In a ravine, 
 
 and buried under a heap of rubljish," at Appin : Capt. 
 
 Carmichael. 
 
 " Stratum spreading, dull, blackish green, bristling all over 
 
 with minute erect fascicles about one- third of a line high. 
 
 Filaments thickish, flexuous, strongly agglutinated together, 
 
 annulated within, pale yellowish. Ahnost like the last species 
 
 in miniature "(//a?'y.), of which it may be but a variety. 
 
 27. Oscillatoria tenuissima Ag. 
 
 Char. " Dark green, ascending, tufted. Filaments simple, 
 cylindrical, even, jcithout any visible joints.'''' — Harv. 
 
 O. tcjiuissima Sm., Eng. Bot. t. 2584. ; Harv. in Hook. Br. 
 Fl. 373.; Harv. in Manual, p. 162. 
 
260 OSCILLATORE^. 
 
 Hah. In the celebrated warm waters of Bath, spreading 
 rather unequally in broad velvet-like patches, of a dark 
 green colour: Rev. H. Davies. 
 
 *' The irregularity of its appearance arises from the fila- 
 ments being collected together into little ascending tufts, 
 apparently rooted in the muddy deposit of the water. Each 
 tuft proves, on examination, to consist of simple uniform even 
 filaments, crowded together and quite pellucid, and equally 
 destitute of joints and branches : their diameter is not more 
 than the eighth or tenth thousandth part of an inch." — Sm. 
 
 30. MICKOCOLEUS Desmar. 
 
 Char. Filaments simple, straight, brittle, closely striated, in 
 bundles, and enclosed within broad, membranous, and 
 branched sheaths, from the apices of ivhich they protrude. 
 
 Chthonoplastus Kiitzing, Phyc. Gener. p. 197. 
 Derivation. From fiiKpos, small, and koXsos, a sheath. 
 
 This is an exceedingly beautiful and interesting genus ; the 
 younger branches or sheaths usually enclose but two or three 
 filaments, while the older contain as many as fifty or sixty : 
 it is difficult to conceive in Avhat way the filaments become 
 multiplied within the sheath, unless it be by a longitudinal 
 division of them. 
 
 1. MiCEOCOLEUS REPENS Harv. 
 
 Plate LXX. Fig. 3. 
 
 Char. Fronds terrestrial, decumbent, radiating, branches diverg- 
 ing, curled and ticisted, gradually tapering to the extre- 
 mity. Filaments large. Striae subdistant, evident. 
 Oscillatoria chthonoplastes /3 Harv. in Hook. Br. Fl. ii. 
 p. 373. Oscillatoria repens Ag. Syst. p. 61. Conf. 
 vaginata, Eng. Bot. t. 1995. Vaginaria vulgaris Gray, 
 Br. Fl. i. p. 280. 
 
MICROCOLEUS. 261 
 
 Hab. " On the naked soil by road-sides, frequent : " 
 Harv. 
 
 " This forms a dull green decumbent slimy stratum. The 
 frond consists of numerous curled branches, diverging from 
 a centre in a starry manner, and gradually tapering from a 
 broad base to a fine point, containing numerous deep green 
 filaments, which radiate and oscillate from the tips, and on 
 laceration issue in bundles." — Harv. 
 
 2. MiCROCOLEUS ANGUirORMIS Harv. 
 
 Plate LXX. Fig. 1. 
 Char. Filaments smaller than in the preceding species. 
 M. anguiformis Harv. MSS. 
 Hah. Saltwater marshes. 
 
 This, although a very distinct species, is a doubtful fresh- 
 water production, and perhaps had better to have been al- 
 together omitted from this work. The AlgcB of our salt- 
 water marshes require a separate study. 
 
 3. MiCROCOLEUS GRACILIS Hass. 
 
 Plate LXX. Fig. 2. 
 Char. Filaments very slender. 
 Hah. Near Aberdeen : Dr. Dickie. 
 
 This is another salt marsh Microcoleus. I detected it 
 amongst some Alga sent me by Dr. Dickie. It is a distinct 
 and pretty little species. 
 
 " Plants, as well as animals, excite the curiosify and interest of the 
 observer, first, by diversities, which distinguish parts and properties and 
 species ; and by similitudes, which lead to the assemblage of species into 
 groups, or genera and classes, &c. : secondly, by grace or beauty of form 
 or colour ; thirdly, by analogies, or affinities of relation, traceable, more 
 or less remotely, throughout all the works of the Creator." — Duncan. 
 
 s 3 
 
262 
 
 Fam. XIV. RIVULAREtE. 
 
 Char. Frond usually gelatinous, lubricous, and definite, in 
 which are embedded Q\?imQntB often flagelliform, sijyiple, or 
 spuriously branched, hilted beloiv, the hilts being formed 
 of an enlarged cell, connected to the filaments by a narrow 
 neck, and filled ivith endochrome. Sheaths in lohich the 
 filaments are enclosed, sometimes saccate beloiv, above at- 
 tenuated and open. 
 No very exact observations have as yet been made upon 
 the reproduction of this family. Do not the enlarged cells 
 which terminate the base of the filaments correspond in 
 function with those of the Nostochinea ? In the setigerous 
 elongation of the filaments a resemblance to Chcetophora is 
 manifested. Certain species exhibit a relation to the Scyto- 
 nemecB. 
 
 31. RIVULARIA. 
 
 Section i. RivuLARiA Roth. 
 
 Char. Frond wart-shaped, rarely encrusting, coriaceous. Fila- 
 ments close, set firmly, adherent, spuriously branched, 
 radiating. 
 Linkia Lyngb. 
 
 1. RiVULARIA PiSUM Ag. 
 
 Char. Frond globose, smooth, shining, dark green. Filaments 
 dichotomous, firmly united. 
 
 Harv. in Hook. Br. Fl. vol. ii. p. 392. ; Berk., Glean. Alg. 
 t. 2. p. 2. 
 
 Hab. On aquatic plants in subalpiue streamlets, Appin: 
 Captain Carmichael. Cheshunt Common : A. H. H. 
 
RIVULARIA. 263 
 
 ^'Fronds a line in diameter, scattered or confluent, of a dark 
 green colour and fleshy firmness. Filaments radiating from 
 the base, dichotomously branched and alternate, the apices 
 free." — Carm. I have no hesitation in referring all the 
 British specimens which I have seen of this species to Rivu- 
 laria botryoides, and these again to R, granuUfera, which spe- 
 cies I consider R. Pisum to be in the earUest period of its 
 developement, and Rivularia hotryoides that species in the 
 middle period of its growth. 
 
 The following is Carmichael's description of R. hotryoides, 
 which, like the preceding, is found attached to stones, &c., in 
 streamlets. 
 
 " Fronds about a line in diameter, hemispherical, Avrinkled 
 and cartilaginous, scattered or running together like a bunch 
 of grapes. Filaments cohering firmly, obscurely striated, 
 dichotomous. Colour, when fresh, black ; on drying, darkly 
 ferruginous." — Carm. 
 
 2. ElVULARIA GRANULIFERA Carm. 
 
 Plate LXV. Figs. 1. 4. 
 Char. Frond large, convex, becoming holloxo underneath, 
 Jleshy, lubricous, broxonish olive, often including stony 
 ■particles, never petrified. 'Filaments slender, Ji?'mly ad- 
 here?^, furnished with a broad sheath. 
 Harv. in Hook. Br. Fl. p. 393. ; In Manual, p. 151. 
 Hah. On clIiFs exposed to the trickling of water, common, 
 annual, Appin : Cajitain Carmichael. — Var. botryoides 
 in streamlets, attached to rocks and stones, co. Antrim : 
 Mr. Bloore. 
 
 " Fronds from a line to half an Inch In diameter, often con- 
 fluent, convex, and at length concave underneath, fleshy, 
 dusky olive green, and extremely sllpper3% Filaments rather 
 thick, repeatedly dichotomous. In the substance are gene- 
 rally enclosed a number of stony particles. This species 
 comes nearest in size and form to R. calcarea, but is never 
 like that petrified with calcareous matter ; and it is moreover 
 
264 mvuLARE^. 
 
 an annual plant, whereas the other exists for several years." 
 — Carm. 
 
 A microscopical examination of these two plants will not 
 only make it evident that the two are specifically distinct, 
 but also most probably generically so. 
 
 Section ii. Raphidia Carm. 
 
 Char. Frond gelatinous, suhglobose, bullated. Filaments 
 few, Jlagelliform, simj)le, moniliform within, scattered 
 through the gelatine, or radiating from a central point. 
 
 1. Eaphidia angulosa Hass. 
 
 Plate LXIV. Figs. 1. 4. 
 
 Char. Fronds gregarious, roundish, gelatinous, hollow, of a 
 bright chestnut colour when recent, changing to dark olive 
 in drying. Filaments large, often j^roduccd into a long 
 and curved setigerous point. Sheath broad, often angular. 
 
 Rivularia angulosa Roth, Harv. in Hook. Br. FJ. p. 394.; 
 and In Manual, p. 153. Ulva pruniformis, E. B. t. 968. 
 Raphania natans Carm. MSS. cum icone. 
 
 Hab. Attached to aquatic plants in ponds and still waters, 
 or floating on the surface, Appin : Captain Carmichael. 
 In a pond on the common east of Lewes and Burwash 
 Road, near Easton Green : W. Borrer, Esq. Swansea : 
 Mr. Ralfs. Cheshunt Marshes : A. H. H. Near Cas- 
 cades, CO. Antrim : 3Ir. Moore. 
 
 '' Fronds gregarious, often confluent, one fourth to three 
 fourths of an inch in diameter, roundish, gelatinous, vesicular, 
 and when detached, rising to the surface of the water with 
 the velocity of an air-bubble. Filaments at the distance of 4 
 or 5 diameters from each other, radiating in all directions from 
 the centre of the vesicle ; rising from a colourless globule, 
 inflated for about one-third of their length, thence tapering to 
 a long slender often curved point. Internal mass moniliform, 
 occupying about one half the diameter of the inflated part of 
 
KIVULARIA. 265 
 
 the filament. Colour pale chestnut, inclining to olive." — 
 Carvi. 
 
 2. Raphidia viridis Hass. 
 Plate LXIV. Figs. 3. 2. 
 
 Char. Frond very mucous, soft. Filaments small, elongated. 
 
 Sheath not evident. 
 /3 marginata. — Filaments rather smaller. Sheath evident. 
 Hah. Near Manchester : Mr. Sidebotham. Aberdeen : 
 
 Dr. Dickie. 
 
 This Raphidia is very distinct. It was sent me by Mr. 
 Sidebotham of jNIanchester put up in fluid. The filaments 
 are not one half so large as those of R. angulosa, but much 
 longer ; the sheath in it could not be detected. In the variety 
 /3 the sheath was quite apparent, and I at first was induced to 
 regard it as altogether different : it is safer however to consider 
 it merely as a variety of R. viridis, or as that species in its 
 perfect condition, the sheath in the specimen sent by Mr. 
 Sidebotham, and which had been put up some time in fluid, 
 having probably become decomposed. 
 
 Section iii. Lithonema Hass. 
 
 Char. Fronds indefinite, truly ramose. Bases of the fila- 
 ments 7iot manubriated. Filaments petrified. 
 Derivation. From \1d09, a stojie, and vrj/xa, a thread. 
 
 1. Lithonema calcareum Hass. 
 Plate LXV. Fig. 2. 
 
 Char. Fronds large, orbicular, convex, afterzvards aggregated 
 
 into a broad spongy ci-ust zoned 7vithin, at length petrified. 
 
 Filaments slender, adherent, and dichotoinously branched. 
 
 R. calcarea Sm., E. B. t. 1799.; Harv. in Hook. Br. Fl. 
 
 p. 392. ; also in Manual, p. 150. 
 Hah. On rocks and stones in streamlets and the borders of 
 subalpine lakes. 
 
266 KIVULARE^. 
 
 " Fronds one fourth or half an inch In diameter, circular or 
 slightly convex, sometunes greenish, but oftener of a dark 
 chestnut colour. After a time, they run together Into a flat 
 spongy crust, of indefinite size. On the smooth face of a 
 rock exposed to the trickling of water, I found a sheet of it 
 upwards of a foot in diameter. When broken the crust ap- 
 pears zoned within, so as to Indicate the age of the plant, 
 each zone being equal to a year's growth. At this age, it is 
 always more or less stony, from the absorption of calcareous 
 matter." — Carm. 
 
 2. LiTHONEMA CRUSTACEUM Ilass. 
 
 Plate LXV. Fig. 3. 
 
 Char. Crust very thin, loidely spreading. Filaments attenuated 
 at the base, fastigiately branched above the middle. 
 
 Rivularia Crustacea Carm. MS. R. Crustacea Harv. in 
 Hook. Br. FL p. 393. ; also in Manual, p. 151. 
 
 Hab. On rocks exposed to the spray of cascades, in the 
 hill streams at Appin : Captain Carniichael. 
 
 " Crust of no determinate extent, extremely thin and slimy, 
 black. Filaments one fourth of a line in length, attenuated 
 at the base, fastigiately branched above the middle of an 
 olive green colour." — Carm. 
 
 This species, although decidedly congeneric with L. calca- 
 reum, may at once be distinguished from it by the fastigiate 
 division of its filaments. 
 
 " If you detect any mistakes of mine, I rely on your superior know- 
 ledge to excuse them; for who has ever avoided errors in the wide- 
 extended field of Nature ? Who is furnished with a sufficient stock of 
 observations ? I shall be thankful for your friendly corrections, I have 
 done what I could myself." — Linnaus to Holler. 
 
267 
 
 Fam. XV. NOSTOCHINE^. 
 
 The NostochinecB form one of the most natural and beauti- 
 ful of the famihes of freshwater Algce. The filaments are 
 simple, of uniform diameter, elegantly raoniliform, resembling 
 strings of pearls, in the highest degree flexible, and of ex- 
 ceeding lubricity. The species of which it is composed 
 naturally arrange themselves into two divisions : in the one 
 the filaments are free, and in the other imbedded in a mucous 
 matrLx, which sometimes assumes a definite form. 
 
 At intervals, in the course of the filaments, are observed 
 cells larger than those which compose the thread itself: these, 
 in the genus Anahaina are more or less of an oval or elongated 
 form ; while in the genus Nostoc they are exactly spherical. 
 They are generally supposed to be connected with reproduc- 
 tion; but hitherto no precise observations have be^n made 
 upon them. In most, and perhaps in all the species of JVostoCf 
 many of these enlarged cells are scattered singly and de- 
 tached throughout the mucous matrix : they have doubtless 
 become separated from the filaments of which originally they 
 formed a link. 
 
 If a Nostoc in the first period of its developement be ex- 
 amined, it will be observed to consist of a single moniliform 
 thread, short, and but little curved, immersed in a mucous 
 nidus. In each of the fully developed specimens of most of 
 the Nostocs, however, threads innumerable present themsches. 
 Now the question arises, in what way are those thi-eads mul- 
 tiplied? First, and chiefly I conceive, by the separation or dis- 
 location of the enlarged cells, whereby each filament is divided 
 into other shorter filaments ; and in the second place, probably 
 by the growth of those vesicles themselves; but on this point 
 nothing positive is known. Independently of these two modes 
 of multiplication of the threads in each frond, no other con- 
 ceivable method exists. The filaments in every example of a 
 
268 NOSTOCHINE^. 
 
 true Nostoc, whether young or old, i^resent one uniform dia- 
 meter ; there are no gradations of size. It cannot therefore be 
 supposed that the threads are increased in number by the 
 effusion of the minute contents of the cells. 
 
 The multiplication of the threads in a frond having been 
 as it seems to me satisfactorily accounted for, the manner of 
 the formation of new fronds remains to be determined. When 
 a Nostoc has arrived at the full and last period of its develope- 
 ment, the pellicle formed by the inspissation of the mucous ma- 
 trix bursts : the mucous contents and the filaments are effiised : 
 these last become disarticulated, so as to form short fragments, 
 each of which retains about it a portion of mucus, so that in 
 this state it corresponds with a Nostoc in the first period of its 
 developement. In this mode of multiplication, remarkable as 
 it is, there is nothing generically peculiar. A Conferva multi- 
 plies itself occasionally by the disarticulation of the filaments. 
 The only difference between the case of the Nostoc and the 
 Conferva is, that the process in the first is natural, and in the 
 second artificial. While, howevei', the separation of the pri- 
 mary filaments accounts amply and satisfactorily for the mul- 
 tiplication, not only of the threads of a frond, but also for 
 the Increase of a number of the fronds themselves, it falls 
 short of explaining the first developement of the first thread. 
 The species of the genus Nostoc, like the freshwater AlgcB in 
 general, are short-lived : in the course of a few months they 
 pass through the stages of their developement ; they die, dis- 
 appear ; the filaments themselves are destroyed ; and then are 
 seen no more until the advent of another season. It is plain, 
 therefore, that the true mode of reproduction of the species of 
 this family is something more than a mere separation of the 
 filaments into fragments. It is now, that in my view we 
 learn the real nature of the enlarged vesicles : ,these are the 
 true reproductive bodies, at the season not j^roper for their 
 developement, lying concealed in tlie earth, awaiting their 
 appointed time to start into growth, activity, and life — 
 all else of the plant, the mucus and the filaments, utterly 
 perishing. 
 
 In the " Annales des Sciences ^^aturelles," third series. 
 
NOSTOCHINE^. 269 
 
 tome ii., there are some interesting observations on tlie re- 
 production of Nostoc vcrrucosum by ]\I. Gustave Thuret, of 
 whose accurate and skilful researches I have already had oc- 
 casion to avail myself in the Introduction. 
 
 " When the plant has arrived at its full developement, the 
 external pellicle, formed by the thickened mucilage, breaks, 
 and permits the escape of the green jelly, which is composed 
 of mucilage and threads. These last scatter themselves in the 
 water the more easily, that they are endowed at that time with 
 a spontaneous motion, analogous to that of the Diatomacca. 
 This curious phenomenon has been already observed by 
 Vaucher, who believed he had found it, although much more 
 evident in all the other Nostocs. In spite of the assertion of 
 that conscientious observer — in spite of the earnestness with 
 which he sought to generalise this fact (Hist, des Tremelles, 
 p. 215. et suiv.), it is difficult to compare movements at least 
 equivocal, with mobility so evidently spontaneous, which the 
 threads of the Nostoc verrucosum possess. Perhaps it is not 
 without some interest to remark on this subject, that the 
 spontaneous movements, the locomotion, are again met \vith 
 under different forms, in the Algce, which, like the Nostocs, 
 live in running waters — in the Oscillatorice, in the spores of 
 Vaucherice, the Confervece, &c., and that this faculty appears 
 to be a condition of their station. 
 
 " To observe well this phenomenon in the Nostoc verru- 
 cosum, the most simple way is to place in a plate filled with 
 water some fine specimens freshly gathered. At the end of 
 two or three days the external skin breaks, the threads ex- 
 pand in the water, and form at the bottom of the plate, or 
 on the sux-face of the liquid, a green scum, nearly like that 
 of the Oscillatoria. If then you have recourse to the mi- 
 croscope, you obser\e that the threads, originally very long, 
 and winding in a thousand ways, are divided into a number 
 of fragments of unequal lengths, all nearly straight, or 
 scarcely bent, which move in the direction of their lengths, 
 and seem to creep upon the surface of the object glass. The 
 larger globules are detached and immoveable; no increase 
 of magnifying power or mode of clearing, no re-agcnt, no 
 
270 NOSTOCHINE^. 
 
 coloured infusion betrays the presence of vibratile ciliae ; 
 and we cannot believe that the threads turn on themselves, 
 because the granulations of the green matter do not change 
 place during the progression. I have seen threads of 
 three seeds move, but never a single seed. If you continue 
 to observe for some days, you will see the thread become 
 immoveable, increase in size, at the same time develope the 
 mucilage with which they are surrounded as with a transparent 
 sheath. Soon the seed enlarges considerably, and divides to 
 form two others, but sideways, and not in the direction of 
 the length of the threads. 
 
 " This formation is repeated many times, and it would seem 
 natural to seek in this circumstance the origin of new 
 threads. Unfortunately the increase of the number of grains, 
 by diminishing the transparency, prevents one following the 
 increase with the same facility. Their confused mass fills 
 entirely the young Nostoc, which is developed in a very irre- 
 gular manner, and takes a variety of forms. It is but later 
 when the mucilage is most abundant, when the seeds are less 
 crowded in the interior of the Nostoc, that you begin to 
 distinguish the threads." 
 
 The NostochinecB of the first section are mostly of a lively 
 and exquisitely delicate green colour. They are wonder- 
 fully prolific, increasing to such an extent frequently as to 
 impart their beautiful colour to extensive tracts of water, 
 as also do occasionally certain species of OscillatoricB. One 
 species described by ]\Ir. Thompson, Anabaina ? spiralis, and 
 which I have named in honour of its discoverer. Spirillum 
 Thompsoni, imparted its colour to the entire of an extensive 
 lake, Ballydrain, which extends over about twenty acres of 
 ground near Belfast* The Oscillatoria arugescens of Drum- 
 mond in like manner imparted its rich green colour to an 
 extensive lough in the north of Ireland, Glaslough, whose 
 waters seemed greened as though by the reflection of trees. f 
 
 * For an interesting paper, by Mr. Thompson, on this Alga, see 
 " Annals of Nat. Hist." vol. v. 
 f See Annals Nat. Hist. vol. i. 
 
NOSTOCHINEJi:. 271 
 
 Leaving the limits of our own country, MM. Engelhardt and 
 Treschel have described a minute Alga, which they have named 
 Oscillatoria rubesccns, and which tinges with a red colour 
 the lake of ISIorat, in Switzerland, assuming sometimes a 
 very beautiful arrangement, depending upon the motion of 
 the water in which it is immersed.* 
 
 But it is not in fresh water merely that the productions of 
 this family are found; they likewise have been noticed to 
 occur in vast quantities in the sea, In different parts of the 
 world ; and It has been ascertained that the Red Sea owes its 
 name to the periodical developement of a species of this 
 family, the Ttnchodcsmium Ehrenbergii Montagne. The 
 name of Ehrenberg has very properly been appended to 
 this species by Dr. JNIontagne, that illustrious naturalist 
 being not merely the first to describe the species, but also 
 the first to discover and record the important and wonderful 
 fact that to a production In its individual parts so minute and 
 insignificant, the Red Sea owes its name and appearance. 
 This Interesting discovery, however, of Ehrenberg Avas for 
 many years overlooked, the account of It having been pub- 
 lished In a Avork not devoted to natural history, but to 
 chemical science, " Annals of Poggendorf." The following 
 translation cannot fail to Interest : — 
 
 " During the year 1823," observes M. Ehrenberg, "I made 
 a stay of many montlis at Tor, upon the borders of the Red 
 Sea, close to jNIount Sinai. On the 1 Otli of December I there 
 saw the surprising phenomenon of the blood-red colouration 
 of all the bay which forms the port of that city. The high 
 sea, without the boundary of the corals, preserves its ordi- 
 nary colour. The short waves of a tranquil sea bring upon 
 the banks during the heat of the day a mucilaginous matter 
 of a blood-red colour, and deposit It upon the sand, In such a 
 manner as that in the course of a good half hour all the bay 
 with the receding tide Is surrounded with a red border of many 
 
 "•" Notice sur la matiere qui a colore en rouge le lac JNIorat, en 182.5, par 
 De Candolle, dans les INIeraoires de la Societe de Physique et d'llistoire 
 Naturelle de Science, 1825, vol. ii. witb fis^. 
 
272 NOSTOCHINE^'. 
 
 feet in depth. I i-emoved from the water some specimens with 
 glasses, and carried them to a tent which I had near the sea. 
 It Avas easy to perceive that the colouration was due to little 
 tufts, scarcely visible, often greenish, and sometimes of an 
 intense green, but for the most part of a deep red : the water 
 upon wliich they floated was always colourless. This very 
 interesting phenomenon, sufficient to afford a reason for the 
 etymology of the name which this sea has received (an ety- 
 mology up to the present time always buried in complete 
 obscurity) — attracted all my attention, and I examined it at 
 leisure with all the care of which I was capable. During 
 many days I observed also the colouring matter Avith the 
 microscope : the tufts Avere formed of little bundles of fila- 
 ments of an Oscillatoria ; they Avere fusiform and elongated, 
 irregular, having rarely more than the diameter of a line, 
 and Avere contained in a sort of mucilaginous sheath ; but 
 neither the filaments taken separately in each fleece, nor 
 the fleeces themseh^es resembled each other. When the 
 sun shines in the horizon, I observed, moreover, that these 
 last maintained themselves upon the surface of the Avater 
 in the glasses Avhich I had brought Avith me, and that 
 during the night, and Avhen I shook the vessel, they reached 
 the bottom. Some time afterwards they remounted to the 
 surface. 
 
 " The plienomcnon of the Red Sea Avas not permanent, but 
 periodical. I observed it three other times, the 25th and 
 30th of December, 1823, and the 5th of January, 1824." 
 
 The same plieuomenon of the colouration of tlie Red Sea, 
 although on a scale infinitely more surprising, has occurred 
 also more recently to other observers, especially to ]M. Evenor 
 Dupont, a very distinguished advocate of the Isle of Mau- 
 ritius, who also accurately determined, as did Ehrenberg 
 previously the cause of this colouration, although he had no 
 knowledge but that the discovery was entirely ncAV to sci- 
 ence, and which he found to be an Alr/a, Avhich Dr. INIontagne 
 has ascertained to be identical Avith that described by the 
 Prussian naturalist. 
 
 The letter of M. Evenor Dupont is so very circumstantial 
 
NOSTOCHINE^. 273 
 
 and satisfactoiy, and corroborative of Ehrenberg's account, 
 that its introduction cannot but be approved of. It is ad- 
 dressed to his friend M. Isidore Gcoffroy-Saint-Hilaire. 
 
 " ]\Iy dear Friend, 
 
 " You demand of me certain details In reference to the 
 circumstances in which I gathered the Cryptorjamic plant 
 which I sent you from the Red Sea, and which you told me 
 appeared a new species. They are as follow : — 
 
 " The 8th July last (1843) I entered into the Red Sea 
 by the Strait of Babelmandcl upon the steam-boat the At- 
 alanta, belonging to the Indian Company. I demanded of 
 the captain and the officers, who for a long time navigated in 
 these latitudes (parages) wliat was the origin of this ancient 
 name of the Red Sea; if it was owing, as some have pre- 
 tended, to sands of that colour, or, according to others, to 
 rocks. None of these gentlemen could reply to me; they 
 nevei', they said, remarked any thing to justify this denomi- 
 nation. I observed then for myself as we advanced : Avhether 
 the ship approached by turns the Arabian coast or the African 
 coast, the red was in no part apparent. The horrid moun- 
 tainous barriers which border the two banks were uniformly of 
 a blackish brown, except where in some places the appearance 
 of an extinct volcano had left long white streams. The 
 sands Avere wliite, the reefs of coral were white also ; the sea 
 of the most beautiful ca3rulean blue. I had given up the 
 hope of discovering my etymology, 
 
 " On the 15th of July the burning sun of Arabia awoke 
 me suddenly by shining all at once, from the horizon without 
 spot, and In all its splendour. I turned myself mechanically 
 towards the window of the poop to seek a remnant of the 
 fresh air of the night before the ardour of the day had de- 
 voured it. What was my surprise to behold the sea tinted 
 with red as far as the eye could reach ! Behind the ship, 
 upon the deck, and on all sides I saAv the same phenomenon. 
 
 " I interrogated the officers anew. The doctor pretended 
 that he had already observed this fact, which was, according 
 to him, produced by the fry of fish floating on the surface ; the 
 
 T 
 
274 NOSTOCIIINE^. 
 
 others said that tliey did not recollect having seen it before. 
 All seemed surprised that I should attach such interest to it. 
 
 " If it be necessary to describe the appearance of the sea, I 
 should say that its surface was covered with a compact stratum 
 of but little thickness, but of a fine texture, of a brick red, 
 shghtly tinged Avith rouge ; sawdust of this colour, of ma- 
 hogany, for example, would produce very nearly the same 
 effect. It seemed to me, and I said at the time, that it was 
 a marine plant. No one seemed of my opinion ; so with a 
 pail tied at the end of a rope I was able to gather, with one 
 of the sailors, a certain quantity of the substance : this with 
 a spoon I introduced into a white glass bottle, thinking 
 that it would be the better preserved. The next day the 
 substance had become of a deep violet, and the water had 
 taken a pretty pink tinge. Fearing that the immersion 
 would hasten the decomposition instead of preventing it, I 
 emptied the contents of the bottle upon a piece of cotton (the 
 same which I remitted to you). The water passed through it 
 and the substance adhered to the tissue. In drying it became 
 green, as you actually saw it. I ought to add, that on the 15th 
 of July we were by the side of the town of Cosseir ; that the 
 sea was red the whole day ; that the next, the 16th, it was the 
 same until near mid-day, the hour at which we found ourselves 
 before Tor, a little Arabian village, the palms of which we per- 
 ceived in an oasis on the border of the sea, below the chain of 
 mountains which descends from Sanai, even to the sandy shore. 
 A little after mid-day, the 16th, the red disappeared, and the 
 surface of the sea became blue as before. The 17tli we cast 
 anchor at Suez. The red colour had consequently showed itself 
 from the 15th of July, towards 5 o'clock in the morning, up 
 to the 16th, nearly an hour after mid-day; that is to say, 
 during thirty-two hours. During this interval the steam- 
 boat, making eight knots an hour, as said the sailors, had 
 traversed a space of 256 miles, or 85 leagues and a third. 
 
 " In the different works relative to Egypt and the Red Sea 
 which I have had occasion to read, I do not recollect to have 
 found mention made of a similar fact : it appears to me, 
 nevei'theless, but little probable tliat it has not been ob- 
 
NOSTOCIIINE^. 275 
 
 served by others. I reproached myself for not having ques- 
 tioned the Arabian pilot Avhom we had on board, and who 
 for twenty years traversed that sea. This idea unhappily 
 presented itself too late. 
 
 " If it should be in your opinion worth the pains, I would 
 demand new observations of the surgeon or officers of the 
 Atalanta, for it would be easy for me to write to them by 
 way of Alexandria. 
 
 " Believe me, my dear Geoffroy, &c. 
 
 " EVENOR DurONT." 
 
 Numerous other navigators and naturalists have noticed the 
 colouration of different portions of the ocean, but these for 
 the most part have not determined the exact nature of the 
 cause, most of them attributing the phenomenon to minute 
 animals. CrustacecB and Mollusca. Two English naturalists, 
 in describing it, have distinctly stated the cause to be an 
 Alga, the species of which, however, they did not determine. 
 The first of these, Mr. Darwin, observed the phenomenon 
 in the Atlantic ocean near Brazil, and not far from the Isles 
 of Abrolhos. The other. Dr. Hinds, of H. M. ship Sulphur, 
 encountered the same Alga at the same spot in which it was 
 originally discovered by Mr. Darwin, and again observed it 
 in the month of April 1837, while at anchor at Libert}^ near 
 San Salvador, w\)0\\ the western coast of America, latitude 
 14° north. Mr. Plinds on both occasions remarked that the 
 plant emitted a strong and penetrating odour, and many 
 persons on board experiencing an irritation of the eyes, fol- 
 lowed by an abundant secretion of tears, attributed the af- 
 fection to the presence around the ship of the Alga. IMr. Hinds 
 took the precaution to preserve sj^ecimens of his plant, some 
 of which were entrusted to Mr. Berkeley for publication, 
 who forwarded them to Dr. Montague, who ascertained tliat, 
 though belonging to the genus TricJwdcsmimn, the jjlant was 
 specifically distinct therefrom, and named it T. Hiiidsii. 
 
 I have been led, in having introduced the above account of 
 the colouration of the waters of the sea, to depart from the 
 strict limits of this work. The phenomenon is, however, so 
 
 T 2 
 
276 NOSTOCHINE^. 
 
 analogous to what has been observed, though of course on a 
 scale much smaller in portions of fi*eshwater, that the one 
 can scarcely be considered complete without a reference to the 
 other, and both are of the highest interest. In the '* An- 
 nales des Sciences Naturelles," 3d Series, t. ii., there is an 
 able and elaborate memoir by Dr. Montagne, one of the first 
 Cryptogamic Botanists of Europe, " Sur la Phenomene de 
 la Coloration des Eaux de la Mer Rouge," wliich contains 
 a great number of references to Avorks in which mention 
 has been made of the phenomenon of the colouration of the 
 sea. 
 
 The sudden and periodical colouration of vast extents of 
 the sea, has been, to uninformed minds, in early times, a sub- 
 ject of superstition and dread, these appearances having been 
 regarded by the ignorant as Divine manifestations of anger 
 or impending calamity ; and that they should have been so 
 regarded in days in which natural science Avas all but un- 
 known, is scarcely surprising. The true explanation of the 
 cause of these sudden and remarkable appearances, while it 
 removes all feelings of superstition or dread, does not banish 
 those of amazement and admiration wliich indeed supplant 
 them. 
 
 The following appropriate observations in the memoir of 
 INIontagne, already referred to, occur : — 
 
 " The singular phenomenon of the colouration produced on 
 the surface of the Red Sea, — a colouration in which we 
 have seen the waters themselves do not participate, has 
 been, each time that it occurs, a new subject of astonish- 
 ment for the people who have witnessed it. It cannot be 
 doubted, moreover, that the jugglers and charlatans, after 
 having probably calculated in advance Its periodical return, 
 made use of it to govern the multitude by the menace 
 of an approaching calamity, of which they failed not to pre- 
 sent this sign as the undoubted precursor. It is also to a 
 cause, if not altogether similar, at least very analogous, that 
 is to be attributed, according to many naturalists, in the 
 number of whom figures M. Ehrenberg, those rivers, waters, 
 and lakes changed into blood in one of the plains of Egypt, — 
 
SPIRILLUM. 277 
 
 an explanation which M. Morren considers somewhat hazard- 
 ous, although not improbable. As to the phenomenon of the 
 Eed Sea, by the fact that its extent has impressed upon it a 
 character of majesty calculated to affect strongly the imagin- 
 ation of the vulgar, it ought to produce still more sensation. 
 Since now Ave know the origin of it, if we compare together 
 the immensity of this phenomenon, and the infinite smallness 
 of the being which produces it, one cannot divest oneself 
 from a profound sentiment of adraii'ation for the Omnipotence 
 which eifects such great ends with such feeble means." 
 
 Section i. 
 Filaments not enclosed in gelatine of a definite form. 
 
 32. SPIRILLUM J?/«-. 
 
 Char. Filaments spiral, aruginons green. 
 
 1. Spirillum Jenneri Hass. 
 Plate LXXV. Fig. 5. 
 
 Char. Filaments rather thick, each being usually composed of 
 about eight or ten regidar spii-al coils. Striie distant, per- 
 ceptible. 
 
 Ilab. Tunbridge : Mr. Jenner. 
 
 This is the finest species of the genus. I have not seen a 
 pure specimen, those sent me by Mr. Jenner being mixed 
 up with different species of Oscillatorice. 
 
 2. Spirillum rupestre. 
 Plate LXXV. Fig. 6. 
 Char. Filaments slender, rcgularhj spiral. 
 Oscillatoria spiralis Carm. 
 
 Hab. On rocks by the seaside where the birds are in the 
 habit of resting, Appin : Capt. Carmichacl. 
 
278 NOfciTOCHINE^. 
 
 " It sjoreacls over the dry naked earth. Stratum several 
 feet in extent, firm, coriaceous, of a glossy black colour, void 
 of lubricity. Filaments about half a line in length, twisted 
 like a corkscrew, radiating in all directions." — Carm. 
 
 When dried, the filaments lose their regularly spiral 
 character. 
 
 3. Spirillum minutissimum Hass. 
 
 Plate LXXV. Fig. 8. 
 
 Char. Filaments excessively small, describing usually about 
 three turns. 
 Hah. Ireland: Mr. Moore. 
 
 This exceedingly minute species I received from Mr. INIoore. 
 The spiral character of the filaments is retained in drying, 
 which is not the case in the pi'evious species. I was much sur- 
 prised to notice, when examining a portion of a specimen 
 which had been preserved for a considerable time, that tlie 
 filaments were in lively movement, turning round and round 
 repeatedly, and with exceeding rapidity. 
 
 4. Spirillum Thompson i Hass. 
 
 Plate LXXV. Fig. 7. 
 
 Char. Threads rather large, moniliform. Globules of equal 
 size throughout their entire length. 
 Anahaina ? spiy^alis Thompson, Annals of Xat. Hist. vol. v. 
 Hab. Ballydrain Lake, near Belfast : 3fr. Thompson. 
 
 " The specimens obtained Avere invariably of similar 
 breadth, and rarely presented more than four spiral turns, and 
 when of this size were one fiftieth of an inch in length. The 
 species at first, when mingling with the water, is of a dark 
 green colour ; when in calm weather it ascends to the surface 
 in separate particles, it appears pale green ; when it does so 
 e?i masse (the earliest symptom of decay), it is of a pale blue ; 
 and in the last stage of decomposition, ferruginous. Having 
 on the 27th September brought home in several phials spe- 
 
Al'lIAMIZOMENON. 279 
 
 cimens of what I had presumed to be this plant in all its 
 stages (i. e. from its first to its last appearance as a coloin-ing 
 matter), I Avas much pleased to have the conjecture verified 
 by microscopical examination. A portion taken from the 
 surface when it appeared pale green was, under the mi- 
 croscope, of as dark a hue as in July, Avhilst the blue and fer- 
 ruginous colours exhibited different stages of decomposition. 
 When in the most perfect state in which the plant has 
 occurred to me, the globules appear entirely filled with 
 granules ; but when very highly magnified are each found to 
 be surrounded by a hyaline membrane. The blue and ferru- 
 ginous tufts exhibited generally its empty globules and the 
 escaped granules scattered all about; but the former were 
 seen in every state from full to empty ; some had granules 
 only in the centre, others were half full, and some separate 
 globules were entirely filled with the granular mass. 
 
 " When two of the spiral portions come in contact, they 
 have an elastic power, by which they can, though slowly, 
 disentangle themselves and separate from each other, a fact 
 which I witnessed in various instances ; but under such cir- 
 cumstance only did I ever perceive any motion in this Alga.'' 
 
 " In some respects the Anah. spiralis resembles the Anab. 
 impalpahilis Bory, as described in the " EncycloiDcdie Metho- 
 dique ; " but its dull green unlustrous hue on paper is quite 
 opposed to that of the species just named, which is described — 
 Preparee sur le papier, ou on a facilite son dcveloppcment, 
 elle est de la teinte la plus brillante, tirant sur celle de I'oxide 
 du culvre, et luisant comme si on I'eut enduite d'eau de 
 gomme." Besides, were this species of the exact spiral form 
 of that under consideration, this cliaracter would not I con- 
 ceive have been unnoticed in the description." — Thompson. 
 
 33. APHANIZOMENON Morren. 
 
 Char. " Filaments simple, cylindrical, Jlexile, membranaceous, 
 glossy, articulated, cohering together injlat lamellcp, lance- 
 olatcd at the apex, straight, or here and there inflated, full 
 of green matter, oscillating spontaneously, falling into 
 pieces.'"' — Morren. 
 
280 NOSTOCIUNE^. 
 
 Derivation. From aipavL^o/xsvov, a vanisliing thing. 
 
 " It is evident that this genus unites the true Conjugates 
 to the Zygnemata by a union well marked in the latter, but 
 being a simple soldering in the Aphanizomena : it relates the 
 Conjugates with the LaminaricB of the sea by the form of the 
 lamella, which results from the soldering of the threads : it 
 establishes an analogy between the Oscillatorice and the Con- 
 ferv<2, by demonstrating that a movement of reptation, of 
 swimming, or of oscillation, may appertain also to the organi- 
 zation as of the ConfervcB as to that of the OscillatoricB, in 
 which the characters of anlmality are supposed to be recognised: 
 the inflated vesicles unite the Aphanizomena to the Conferva 
 vesicata of Agardh, and the cells as well as the organization 
 of the threads themselves maintain with the true Conferva 
 relations so clear, that it would be improper to place other- 
 wise than amongst them this new genus." — Morren. 
 
 The true jjosition of the genus is undoubtedly amongst the 
 Nostochinecs, imiting them Avith the Oscillatorics. Tlie ana- 
 logies indicated by Bory are more imaginary than real. 
 
 1. Aphanizomenon INCURVUM Morren. 
 
 Plate LXXVI. Fig. 6. 
 
 Char. Lamella plain, rchitish green, incurved. Threads 
 cohering. Cells /ro?n two to eight times as long as broad. 
 
 INIorren, in memoir read before the Royal Academy of 
 Brussels, in Dec. 1839: Thompson, In Annals of Nat. 
 Hist. vol. v. p. 82. ; Harv. in Manual, p. 145. 
 
 Hab. In sheltered creeks, floating on the surface ; Bally- 
 drain Lake : JF. Thomjjson, Esq. Grand Canal docks, 
 near Dublin : Professor G J. Albnan. In the pond of 
 the Dublin Zoological Gardens : Miss Ball. 
 
 " Towards the middle of the month of ]\Iay, up to July, the 
 waters of the lakes, the ponds, and the basins Avhich surround 
 the country houses In Flanders are noticed to present tufts 
 of a whitisli green, and of a size which varies from that of a 
 
ANABAINA. 281 
 
 little pea to that of a melon. These tufts, which appear afar 
 off cloud-like, are placed at a distance, the one from the other. 
 One would consider them immovable ; but seen nearer, they 
 enjoy a veritable power of locomotion wliich allows of their 
 being met at all heights in the waters. I have observed this 
 year again a prodigious quantity of it at Gentbrugghe, near 
 Gand." — Bory. 
 
 Mr. Thompson, who Avas the first to notice in Ireland tliis 
 species, observes, in his remarks on it in the "Annals of Natural 
 History," loc. cit. — " In Bally drain Lake I have, both in 1838 
 and 1839, remarked its presence on very calm days, for it is 
 only at such times visible during the month of July, August, 
 and September, and then it appears in the most sheltered 
 creeks only, floating in patches of various dimensions." 
 
 It has not yet been found in Great Britain. 
 
 34. ANABAINA Bory. 
 
 Char. " Filaments frequently elegantly moniliform, curved, 
 invested ivith mucous matter, and having a vermicular 
 motion resembling that ofwojins." — Bory. Eeproduction 
 consisting of sjwrxdes contained m enlarged cells, the f 07-771 
 aiid size of lohich varies accordi7ig to the species. 
 De7ivation. From ava, up, and jSawo), to 77iounf. 
 
 " Their movement exhibits a relation with that by means 
 of Avhich the earthworms move from place to place ; they are 
 progressive, and the curves which they describe are of extreme 
 slowness. It is by this amlndatory faculty principally that 
 the aquatic species elevate themselves to the surface of the 
 water, traversing the length of Co7ifervcB and the remains of 
 vegetables, mount to the surface of reeds and carices, pene- 
 trate the slime and the Oscillatorice, which they surmount in 
 such a way that they merit the name derived from the 
 Greek, by which we have proposed to designate them." 
 
 The remarks of Bory in the above quotation appear to me to 
 be somewhat fanciful and overstrained. I much doubt whether 
 this mounting upwards of the A7iahai}m partakes in any dc- 
 
282 NOSTOCHINE^. 
 
 gree of a voluntary character, and whether the explanation 
 given of the elevation to the surface of the waters of almost all 
 the Conferva is not sufficient to account for that of the Ana- 
 haincB. The explanation allucled to is the fact that during 
 respiration a gas is eliminated, the globules of which be- 
 coming, entangled in their filaments, renders them specifically 
 lighter than the water, and so causes them to ascend. 
 
 1. Anabaina flos-aqu^ Bory. 
 Plate LXXV. Fig. 2. 
 
 Char. Filaments large^ beautifully moniliform, and variously 
 cia-vcd. Reproductive cells numerous, elongated, and for 
 the most part curved. 
 Nostoc Jlos-aqucB Lyngb., Dan. p. 201. t. 68. Anabaina 
 Jlos-aqu(B Bory ; Hudson, Flor. Ang. p. 604. ; Light. 
 Scot. p. 999.; Harvey in Manual, p. 186. 
 
 " This s^Decies attracted my attention when tinging with 
 its delicate green hue the margin of the smallest (?) of the 
 lochs Maben in Dumfries-shire, or that nearest to Jardine 
 Hall (on the road from the village of Lochmaben), as I drove 
 thither on the 15th of August, 1838. The day was calm and 
 bright. My specimens tinge the paper with a verdigris 
 colour, and are quite dull, or wanting in any lustrous ap- 
 pearance. This species is introduced here on account of its 
 having been erased 'of late years from the British Flora. 
 Hudson and Lightfoot included it without assigning to it 
 any British station or locality." — Thompson. The repro- 
 ductive cells, which, as noticed in the definition of the 
 species, are curved to accommodate themselves to the various 
 curvatures of the threads are mostly solitary, and I have 
 never observed more than two contiguous to each otlier. 
 
 2. Anabaixa LiCHENiFOiiMis ? Bory. 
 
 Plate LXXV. Fig. 4. 
 
 Char. Filaments not moniliform, minute, but little curved. 
 
SPII^KOZYGA. 283 
 
 Reproductive cells of various sizes, oval, and occurrimj 
 
 in scries. 
 Bory, iu Diet. Class, d. Hist. Nat. vol. i. p. 309. 
 Ilab. Neiglibourhood of Dublin : Dr. Allman. County 
 
 Wicklow : Mr. 3Ioore. Sussex : Mr. Jcnncr. 
 
 There is no species hitherto recorded with which this can 
 possibly be confounded. The form of the reproductive cells, 
 the various size of these and their occurrence in chains or 
 series serving to mark it from all others. 
 
 3. Anabaina impalpebralis ? BorTj. 
 Plate LXXV. Fig. 3. 
 
 Char. Filaments minide, not moniliform, but little curved. 
 Reproductive cells large and quadriform. 
 Bory, in Diet. Class, d. Hist. Nat. vol. i. p. 309. 
 Ilah. Under a waterfall, co. Wicklow : Mr. Moore. 
 
 This is also a very distinct species ; the reproductive cells 
 are large, elongated, and in the form of a parallelogram, with 
 the angles slightly rounded; they are also usually solitary, 
 rarely in pairs. It dries without gloss. 
 
 4. Anabaina constricta Hass. 
 Plate LXXV. Fig. 9. 
 
 Char. Filaments verrj slender, not moniliforin. Reproductive 
 cells 7nuch elongated, mostly solitary, small. 
 Hah. On mosses, Cheshunt : A. II. II. 
 
 This species bears some resemblance to the jn-cccding ; the 
 reproductive cells are, however, not nearly so large as in it, 
 and are slightly constricted in the centre. 
 
 35. SPHJEROZYGA ^y. 
 
 Char. Stratum gelatinous, in irhich undulate articulated 
 imbrayichcd threads icith quadrangular joints, joined 
 
284 NOSTOCHINEiE. 
 
 here and there to a spherical ccllj tvhich is sometimes 
 terminal. 
 
 1. Sph^rozyga Jacobi Ag. 
 
 Char. Threads radiating, lonely, disposed in gelatine. 
 Sphcsrozyga Jacohi Berk., in Eng. Bot. t. 2826. fig. 2. 
 
 Hab. Northamptonsliire : Rev. M. J. Berkeley. Cromlyn 
 Bog : J. W. Gutch, Esq. 
 
 This species Avould appear from the description to belong 
 to Anabaina or A-phanizomenon. I have never seen it. 
 
 36. TRICHORMUS Allman. 
 
 Char. Frond yr*?^', of undeterminate figure, consisting of simple, 
 minute, moniliform, curved threads, with articidations of 
 uniform size, immersed in a gelatinous matrix. 
 
 Derivation. From ^pL^, hair, and 6pfjL09, a necklace. 
 
 " From Anabaina of Bor}^ Saint Vincent the present 
 Alga, as well as that of ]\Ir. Tliompson (^Anabaina ? spiralis), 
 differs in the uniform size of the articulations, Bory's genus 
 being characterised by larger globules occurring at distinct 
 intervals in the series." — Allman.* 
 
 Although strongly inclined to agree with my excellent and 
 early friend Dr. Allman, as to the validity of the genus Tri- 
 chormus, I am still not altogether satisfied respecting it, the 
 suspicion resting on my mind that the T. incurvus AUm. 
 might possibly be an Anabaina in a young stage of its 
 developement, the reproductive enlarged cells not having as 
 yet manifested themselves. This, however, is but a suspicion, 
 against which may l^e urged the fact that in veritable Ana- 
 baincB the globules are invariably found interrupting the 
 uniformity of the filaments. 
 
 * " On a New Genus of Algse, belonging to the family of the Nosto- 
 chinefe." By G. J. Allman, A.B., L.R.C.S.J., Secretary to the Dublin 
 Microscopical Society. Annals of Nat. Hist. vol. xi. p. 161. 
 
MONORMIA. 285 
 
 1. Trichormus incurvus Allm. 
 
 Plate LXX7. Fig. L? 
 
 Char, " Plant citlicr diffused through the toatcr or collected on 
 the surface. Filaments of a iiea-green colour, croioded 
 together confusedly in a gelatinous matrix, variously curved, 
 but never regularly spiral, assuming, when dried, a fine 
 verdigris-green colour loithout lustre.'''' — Allman. 
 
 AUman in Annals of Nat. Hist. vol. xi. p. 163. 
 
 Hah. In the Grand Canal dock, Dublin, October: Dr. 
 Allman. 
 
 The only authentic specimen which I have seen of this 
 species was so much injured that I was not able to make an 
 examination of it in tlie least satisfactory. A specimen, how- 
 ever, sent me by INIr. Thomj)Son, collected by that gentleman 
 and found floating on the surface of Lough Neagh, at Shane's 
 Castle, marked Anahaina fios-aquce, accords so well Avith the 
 description and figure given by Dr. Allman of T. incurvus, 
 that scarcely a doubt remains as to the propriety of regarding 
 Mr. Thompson's plant as that species, see PI. lxxv. fig. 1. 
 From the true A. fios-aquce INIr. Thompson's si^ecimens differ 
 in the less considerable dimensions of the filaments, and in 
 the absence of the enlarged cells. 
 
 Section ii. 
 Filaments invested in a mucous matrix of a definite form. 
 
 37. :MONOilMIA Berhdey. 
 
 Char. " Frond branched, composed of a single moniliform 
 thread, folloiving the ramifications, imyncrsed in gela- 
 tine:' —Bark. 
 Derivation. From jjlovos, one, and op^os, a necklace. 
 
 This genus scarcely differs from Nostoc, between which and 
 Anabaina it forms a clear link. 
 
286 NOSTOCHINE7E. 
 
 1 . MONOKMIA INTRICATA Berk. 
 
 Plate LXXV. Fig. 11. 
 
 Char. Filaments scarcely moniliform. Reproductive cells 
 
 infrequent, globular, in series. 
 Monormia intricata Berlc, Gl. of Alg. p. 46. t. 18. ; Harv. 
 
 in Manual, p. 185. Nostoc intricatum Menegliini, Mo- 
 
 nographla Nostochinearum Italicarum, p. 122. with 
 
 %. 
 Hah. In ditches of the marsh to the south of Frindsbury 
 
 Canal, near Gravesend, in great abundance in June, 
 
 1832 : Rev. 31. J. Berkeley. 
 
 " Forming small roundish gelatinous masses, floating 
 amongst different species of Lemna in fresh water, but probably 
 within the influence of the tide, and also amongst Enteromor- 
 •plia intestinalis, and even within the frond in brackish water. 
 The plant is at first of an olive yellow, gradually assuming a 
 o-reener tint, and when dried of a deep verdigris. Yery gela- 
 tinous, delicately branched; the branches very flaccid. Under 
 a hio-h magnifier the whole plant is evidently composed of 
 gelatine, in the centre of which runs a single moniliform fila- 
 ment, following the ramifications, and in its progress curhng 
 to and fro repeatedly across the thread, the joints being 
 nearly globular. The specimens from the interior of En- 
 teromorpha are paler, and have often longer joints amongst 
 the globidar ones." — Berk. 
 
 In the authentic specimen which I have examined of this 
 beautiful production, the articulations of the threads them- 
 selves could scarcely be called moniliform, althoiign the large 
 reproductive cells were distinctly so. 
 
 38. NOSTOC Vauch. 
 
 Char. Frond defimte, gelatinous or coriaceous, globose or lohed, 
 filled with curled beaded simple filaments. Eeproduction 
 consisting of enlarged spherical cells placed irregularly in 
 
NOSTOc. 287 
 
 the course of the filaments, from ichich finally they become 
 separated. 
 
 " This name is unexplained : it was first used by Paracel- 
 sus, and adopted by Vaucher for the present group, which 
 before that time was included in Tremella.'^ — Harv. 
 
 1. NoSTOC VARIEGATUM Moore. 
 
 Plate LXXIV. Fig. 3. 
 
 Char. Frond terrestrial, expanded, gelatinous, livid, variable 
 in shape. Filaments rather distant. Cells oval, and 
 variable in size. 
 
 Harv. in Manual, p. 183. 
 Hab. Ireland : 3Ir. Moore. 
 
 " This singular plant I first collected in 183G, growing on 
 the face of a moist bank over which water trickled. When 
 recent it formed a soft gelatinous mass, of a livid colour, 
 bearing the closest resemblance, both in substance and co- 
 lour, to those gelatinous Medusa which are cast ashoi'e along 
 the coast, and called by the country people ' fallen stars.' I 
 again collected it on the same spot in 1838, when I sent Dr. 
 Greville specimens, who thinks it difterent from any thing 
 he knoAvs, and coming nearest to Nostoc commune." — 
 Moore's MS. 
 
 If I had acted on my own convictions in reference to this 
 species, I should have removed it to the genus Anabaina, to 
 which it seems more properly to belong than to Nostoc. In 
 the genus Nostoc there is an exact similarity in all the fila- 
 ments ; in the species under consideration, a considerable 
 want of uniformity is observed, some being composed of cells 
 larger than those of others, as may be seen by the figure, in 
 which particular it resembles Anabaina, as it does also in the 
 diffused or unlimited mucous matrix, in which the thi-eads 
 are imbedded, and in the oval form of the enlarged or repro- 
 ductive cells. 
 
288 NOSTOCHINE.E. 
 
 2. NOSTOC COMMUNE Vauch. 
 
 Plate LXXIV. Fig. 2. 
 
 Char. Frond terrestrial, expanded, membranaceous, plaited, 
 waved, or curled; olive green, shining, and irregular in 
 form. Filaments thick, beautifully moniliform. Repro- 
 ductive cells large, either attached to the filaments, or lying 
 scattered throughout the frond. 
 
 Nostoc commune Vauch., Hist, des Conf. p. 223. pi. xvi 
 f. 1. Tremella Nostoc, Eng. Bot. t. 461. Tremella ter- 
 restris Dill., Muse. p. 52. t. 10. f. 14.; Harvey in 
 IManual, p. 183. ; IMeneghini, INIonographia Nostochine- 
 arum Italicarum. 
 
 Hab. '' Gravelly soils, garden walks, rocks, pastures, &c. ; 
 very common in autumn and winter." 
 
 The filaments are large, exactly moniliform, flexuous, and 
 copious, with here and there an enlarged reproductive cell of 
 an exactly spherical form. These enlarged cells occur either 
 in the course of the filaments, are temiinal, or lie detached in 
 the mucous matrix of the frond. Some writers have laid 
 great stress, in their descriptions, upon the fact of these 
 globules being so frequently terminal. This position of them 
 has nothing to do with the developemcnt of the species, but 
 arises from the thread of which they fomned a link having 
 separated from one side of them — a step preparatory to their 
 being altogether cast oif by the filaments. 
 
 " In prima tantum hujusce speciei letate deprehendenda 
 est interior substantia, aquosa-gelatinosa, qua cito elapsa 
 frons excavata potius quam vesicieformis efiicitur, stratum 
 enim periphericum, ratione habita cavitate interiori, multo 
 crassius est in ceteris omnibus speciebus." — Menegh. 
 
 The only species with which there is any danger of con- 
 founding Nostoc commune are, N. ccerideum and N.foliaceum. 
 The filaments of N. commune correspond in size and appear- 
 ance very closely with those of iV. ccerideum, but the external 
 characters are altogether distinct; the contrary is the case 
 with N. foliaceum, the external characters resembling those 
 
NOSToc. 289 
 
 of iV. commune, but the filaments are different, being much 
 smaller iu size, although, Hkc those of N. commune, distinctly 
 moniliform. 
 
 3. NoSTOC FOLIACEUM Ag. 
 
 Plate LXXVI. Fig. 2. 
 
 Char. Fi'ond membranaceous, erect, plaited, olive green. 
 Filaments slender, copious, moniliform. Enlarged globuli 
 numerous, 
 Nostoc foliaceum Ag., Syst. p. 19. ; Ilarv. in Hook. Br. 
 Flora, ii. p. 399. ; Harv. in Manual, p. 184. ; Meneghini, 
 INIouographia Nostochinearum Italicarum, vol. v. p. 18. 
 seric ii. delle ]\Iemorie della E. Academic delle Scienze 
 di Turino. 
 Hah. On clayey ground kej^t constantly damj) by the 
 oozing of water, Appin : Capt. Cai'michael. Ireland : 
 Mr. Moore. 
 
 ** This species is easily distinguished both by its appearance 
 and station from Nostoc commune, to which it seems similar, 
 as respects certain external characters. It never swells up 
 into the form of a vesicle ; the structure, altogether uniform, 
 extends as a membrane, and rises up by moisture into plicated 
 lobes : it grows on stones, and is evolved, the winter scarcely 
 being ended, when Nostoc commune has not yet appeared."' — 
 Menegh. The difference in the size of the filaments of Nostoc 
 commune and N. foliaceum is perhaps the only character 
 whereby the two species can at all times be discriminated, 
 the threads being much smaller in the latter species. 
 
 4. Nostoc srniEEicuM Vauch. 
 Plate LXXYI. Fig. 5. 
 Char. Frond small, globose, densely aggregated, solid, smooth, 
 olive green, waterg within. Filaments small, moniliform. 
 Nostoc sjdmricum Vauch., Conf. p. 223. pi. xv. f. 2, 
 
290 NOSTOCHINE^. 
 
 Ulva pisiformis Hudson. Conf. pisum, Flor. Dan.; 
 Harv. in Hook. Brit. Flor. p. 400. ; Harv. in Manual, 
 p. 185. ; Menegliini, Monographia Nostochinearum, 
 p. 110. 
 Ilab. In rivulets and fountains, attached to stones, &c. 
 Appin : Captain Carmichael. Pools near Barmouth and 
 Llyn Coron, near Anglesea : Mr. Ralfs. Co. Wick- 
 low : 3/?'. Moore. 
 
 " Fronds from half a line to two lines in diameter, globular, 
 firm, smooth, solid, heaped on each other like a parcel of small 
 shells. Internal filaments rather thinly scattered through the 
 mass." — Carm. 
 
 " This species dried and again moistened sometimes emit a 
 most grateful -^dolet odour, as thovigh it were a species of 
 Chroolepis, and such as no other Alga of the family of Nos- 
 tocMnece presents." — Menegh. 
 
 The filaments are moniliform, and exactly correspond with 
 those of Nostoc foliaceiim in size, the young state of which 
 species, as it agrees with it also in habit, it may eventually 
 prove to be. 
 
 5. Nostoc vesicarium D. C. 
 
 Char. " Frond globose, plicated, greenish yelloxc, the interiial 
 viscid mucus escaped, vesicceform, cartilaginous. Filaments 
 curved, slender, with cells twice as large, thickly interspersed 
 and terminal.''' — Menegh. 
 
 D. C. Flor. Fr. vol. iii. ; Harv. in Hook. Br. Flor. p. 399. ; 
 Harv. in Manual, p. 184.; Ag. Syst. p. 19.; Meneghini, 
 Monographia Nostochinearum, p. 108. 
 
 Hab. Road-side, near Perth : G. A. TV. Arnott, Esq. 
 
 " The diameter of the frond varies from a millimetre to an 
 inch. The colour in the smaller fronds obscurely green, verges 
 in the larger to a yellowish brow^n. Substance firm, cartilagin- 
 ous, including a fluid viscous juice: afterwards, the gelatinous 
 substance having escaped, empty, vesica3form, membranaceous ; 
 
NOSTOC. 291 
 
 threads moniliform, in the interior substance very lax, in the 
 external stratum much more curved than in Nostoc commune, 
 smaller in diameter, tliey scarcely attain three millimetres ; 
 but the larger spherical globules, twice as thick, abound, and 
 sometimes form tracts more or less long, no smaller globule 
 occurring between. In adult specimens the threads are vari- 
 cose wherever they occur." — Menecjhini. 
 
 6. Nostoc verrucosum Vauch. 
 Plate LXXV. Fig. 1. 
 
 Char. Frond attached, large, suhglohose, in the heginning solid, 
 externally suh coriaceous, unthin gelatinous, at length hol- 
 low, vesicceform, verrucose, broitmish green; xohen dried 
 ceruginous. Filaments de7ise, slender, almost cylindrical. 
 Nostoc verrucosum Vauch., Hist, des Conf. Tremellajluvi- 
 atilis Dlllw., Muse. ; Harv. in Hook. Br. Fl. p. 400. ; 
 also in INIanual, p. 185. ; Meneghini, in loc. cit. ; Thuret, 
 in Aunales des Sciences Naturelles. 
 
 Hab. On stones in Alpine streams ; Aberdeen : Dr. 
 Dickie. 
 
 This species may be distinguislied from most others of the 
 genus by the nature of the filaments, which are almost cylin- 
 drical. The species with which it is most likely to be con- 
 founded is Nostoc pruiniforme, the filaments of which resemble 
 it closely, but are considerably larger ; in other respects the 
 two species are widely diflferent, being estranged in form, 
 habit and consistence. 
 
 7. Nostoc pruiniforme Ag. 
 Plate LXXVI. Figs. 3, 4. 
 Char. Frond unattached, solitary, globose, smooth, olivaceous, 
 gclatino-coriaceous, u-ithin watery. Filaments somewhat 
 thick, almost cylindj'ical. 
 
 Ag. Disp. p.45. ; Berk. Gl. p. 48. t. 19. f. 2. ; Lyngb. 
 u 2 
 
292 NOSTOCHINEiE. 
 
 Hydropli. p. 200. t. 68 a. ; Harv. in Hook. Br. Fl. p. 399. ; 
 also in Manual, p. 184. ; Meneghini, loc. cit. p. 114. 
 Hah. In freshwater pools near the coast ; rivulet near 
 Torquay : Sir TV. J. Hooker. Appin : Captain Car- 
 michael. 
 
 ''Fronds unattached, scattered at random in the clefts of 
 the rocks, globular, smooth, olive-green, diaphanous, from \ to 
 1^ inches in diameter, the larger ones generally compressed, 
 hollowed, and sometimes ruptured." — Carvncliael. 
 
 The filaments, as remarked in the description of the j^re- 
 ceding species, resemble those of Nostoc verrucosum in all, save 
 size, being larger than in that species. The reproductive cells 
 are rarely produced. 
 
 8. Nostoc muscorum Ag. 
 
 Plate LXXIV. Fig. 4. 
 
 Char. Frond tuberculate, subcoriaceous, variable in shape. 
 Filaments imtch curved, moniliform, exceedingly slender. 
 
 Ag. Disp. p.44. ; Ag. Syn. p. 132.; Syst. p. 19. ; Harv. 
 in Hook. Br. FL p. 399. N. muscorum Harv., in 
 Manual, p. 183. N. microscopicum Carm., MS.; Harv. 
 in jNIauual, p. 184. ; Meneghini, Nostochinearum Italica- 
 rum, p. 119. 
 
 Hob. N. muscorum, on calcareous rocks, and the mosses 
 which cover them, Appin : Captain Carmichael. — N. 
 microscopicum, on exposed calcareous rocks among 
 mosses, Appin: Captain Carmichael. Near Youghal: 
 Miss Ball. Wilderness, near Clonmel : W. H. Harvey. 
 Clayey banks, co. Antrim : Mr. Bloore. 
 
 I have examined several of Carmichael's specimens of this 
 Nostoc, and compared them with others of Nostoc micro- 
 scopicum Carm., and I entertain no doubt of tlie specific 
 identity of both. All the specimens which I have received 
 of the former have consisted not of single fronds, but of an 
 aggregation of numerous smaller fronds of various sizes and 
 
NosToc. 293 
 
 forms, most of thera being spherical but many of them angular. 
 The filaments are minute, much curved, and the cells are 
 spherical or slightly oval. It is one of the most distinct and 
 beautiful species of the genus. In the smaller specimens, 
 there is but a single thread, which curves in an elegant manner 
 throughout the frond. 
 
 9. NosTOC c^RULEUM Lyiigh. 
 
 Plate LXXVI. Fig. 11. Plate LXXV. Fig. 10. 
 
 Plate LXXIV. Fig. 1. 
 
 Char. Frond solitary, small, globose, solid, fluid within, at 
 
 length vesicular, mostly pale blue, sub-pellucid. Filaments 
 
 large, elegantly moniliform, much curved. 
 
 Nostoc ccsruleum Lyngb., Hydroph. p. 201. No. 6. 768. (3; 
 Grev. Crypt. Fl. t. 131. ; Hook. Brit. Flor. p. 400. ; 
 Harv. in Manual, p. 185. ; ]\Ieneghini, Monographia 
 Nostochinearum Italicarum, p. 111. 
 
 Hab. In flowing water or In very moist places attached to 
 mosses, near Calender : Dr. Greville. Co. Antrim ; near 
 Wicklow : 3Ir. D. 3Ioore. Pass of Lerry : Dr. Greville. 
 
 This species in its dried state might be readily passed over 
 as Nostoc commune in the first pei'iod of its growth, the fila- 
 ments of N. cceruleum according exactly with those of that 
 sjjecies. Notwithstanding the difference In Its colour, and 
 perhaps in its habit also, I am not perfectly assured that It 
 is really distinct. The larger size of the filaments will serve 
 to distinguish It from Nostoc sph(eric2a7i, which In form It 
 resembles, as well as the difference in Its colour, and its 
 greater mucoslty, which causes It to adhere closely to paper. 
 
 10. Nostoc macrosvotivm ? 3Ic7icgh. 
 
 Plate LXXIII. Figs. 1, 2. 
 
 Char. Frond minute, solid, spherical, ceruginous green. 
 
294 NOSTOCHlNEiK. 
 
 Filaments curved, thick, almost cylindrical, with here and 
 
 there an enlarged spherical celhde. 
 N. crassisporum Menegh., Consp. Alg. Europ. p. 7. ; et iV[ 
 
 macrosporujn, Monographia Nostochinearum Italicaruni, 
 
 p. 116. pl.xiv. fig. 2. 
 Hab. Ireland : il/r. Moore. 
 
 Meneghini describes the frond of his N. macrosporum as 
 being polymorphous; in my specimens it was regularly 
 spherical. Meneghiui's description, however, in other respects 
 accords so well with my examples that there scarcely a doubt 
 can exist as to their identity with the N. macrosporum. 
 
 " But different objects stimulate different minds to inquiry. Perhaps 
 the contemplation of the vegetable kingdom may be suited to the varied 
 conditions of more persons than the investigation of the animal structure ; 
 for plants, abundantly bordering our paths, are more readily procured for 
 the purposes of analytical examination, attract more continual attention 
 in our moments of leisure by many trivial allurements, and give little or 
 no shock to the most irritable sympathies during dissection. The vege- 
 table kingdom, as a manifest part of a universally concatenated system, 
 presents unquestionable traces of the great Intelligence -which has planned 
 and constructed the whole. These traces appear so singularly diversified 
 thi'ough every part of the great sphere of human observation, that the 
 conclusion is irresistible, that such diversity has been especially intended 
 as a final cause to awaken admiration in beings of duly adapted intelli- 
 gence, to stimulate feelings made to be in harmony with such display of 
 beauty and of glory ; with a purpose to obviate all doubt, to evoke con- 
 tinual rapture, and to elevate the soul of man through transitions of fear 
 and wonder and awe to adoration and to divine love, which is said to be 
 the perfection of all wisdom." — J. S. Duncan's Botanical Theology. 
 
295 
 
 ALGiE GLOBULIFERiE. 
 
 Fam. XVL ULVACEiE. 
 
 Char. Frond gelatinous, saccate, tubuiose, or membranaceous. 
 Cells either spherical and scattered singly throughout the 
 mucous frond irregularly, in jmirs, in fours, or multijjles 
 of that number ; or jiolygonal, and crowded together. 
 
 The siJecies of the family Ulvacece appear, so far as the 
 freshwater exam23les are concerned, to require a separation 
 into two sections : the first including the genera Ulva, at least 
 the single freshwater species of that genus Ulva bullosa (of 
 the marine species, I have no exact knowledge), Tctrasjyora, 
 Hydrunis, and 3Ieris?nopedia ; the second, the genus Entero- 
 morpha. In the first, the cells are small, and spherical, being 
 imbedded at considerable intervals from eacli other in the 
 mucous frond ; in the second, the cells are large, polygonal, 
 and attached firmly to each other, the mucous nidus having 
 disappeared. 
 
 The reproduction of this family docs not appear to have 
 been satisfactorily determined. In Agardh's memoir on the 
 propagation of the Alga, referred to so often, the following- 
 remarks occur : — 
 
 " My father advanced the opinion that the cellules disposed 
 often in fours were the seeds, which was contradicted by 
 Lyngbye. Grcvillc in the work cited above * observes, that 
 from three to four granules are disposed in the cellules of the 
 frond, but he pronounces not upon the function which ought 
 to be attributed to these granules. In tliis uncertainty, some 
 observations on tlie movement of the globules of Tct rasper a 
 lubrica, should easily decide the question ; but no person 
 
 * Alga; Britannicaj. 
 u 4 
 
296 ULVACEJC. 
 
 having "as yet observed the act itself of their disjunction 
 from the membrane, it has not been ascertained whether it 
 was the cells themselves or that which they contain which 
 escaped from it. That which is certain is, that the sporules 
 of this plant are not more naked (an opinion advanced by 
 ]\I. Gaillon) than those of any other Ulvacece. 
 
 " The Ulvacece properly so called are composed of cells some- 
 times arranged in a single layer, which constitutes an elongated 
 tube entirely empty, sometimes disposed in two layers, com- 
 pressed the one against the other, and forming a flat mem- 
 brane more or less extensive. Their sporules are lodged in 
 these cells, and issuing by a pore situated on the surface, they 
 offer the same phenomenon of locomotion which we have seen 
 to belong to the preceding families. 
 
 " Their movement is more slow and in the cellules straighter 
 than amongst the Confervea. Their beak is not so pointed, 
 and is not near so well separated from the body ; but never- 
 theless it is always the thinnest end of the oviform bodies 
 which is foremost during the movement. The sporules are 
 five or six in number in each cellule ; in some of them there 
 were two or three which were much smaller than the others, 
 a difference which is also observed in the ConfervecB, but in a 
 manner less apparent. 
 
 " Finally, it is only in the Ulva clathrata that I have ob- 
 served the complete developement of these sporules. The ger- 
 mination (if one may so name a phenomenon analogous to that 
 act in more perfect plants) consists in this species of a longi- 
 tudinal expansion, during which the green matter insensibly 
 transforms itself into transverse bands. In this state one 
 might easily take the young plant for a species of Conferva, 
 but soon the bands being divided longitudinally, and so become 
 disposed in two series, one cannot longer mistake it." 
 
 Section i. 
 Granules simjjly imbedded in the frond. 
 
 39. ULVA Linn. 
 Char. Frond gelatinous, saccate or membranaceous. Cells 
 
ULVA. 297 
 
 scattered tlirmigh the frond cither sinf/hj, in pairs, or in 
 fours. 
 Name supposed to be from ul, water. In Celtic. 
 
 1. Ulva bullosa Both. 
 
 Plate LXXVIII. Fig. 13. 
 
 Cha7\ Frond very delicate, somewhat gelatinous, at first sac- 
 cate, afterwards becoming expanded into a broad waved 
 or torn floating membrane. 
 
 Eng. Bot. t. 2320.; Hook. Brit. Flor. vol. ii. p. 312.; Harv. 
 in Manual, p. 171. 
 
 Ilab. In stagnant freshwater ponds and ditches. 
 
 Fronds clustered, at first fixed, afterwards floating, very thin 
 and gelatinous, of a pale green colour, becoming yellowish. 
 Cells in the fully developed plant single, and equally diffused 
 throughout the lamina. If this disposition of the cells be not 
 constant, and if in the young condition of the frond they are 
 ever arranged in fours, as I believe to be the case, then I think 
 that this species can scarcely be regarded as distinct from 
 Tetraspora lubrica. The size of the cells is the same in both. 
 
 2. Ulva ckispa Light. 
 Plate LXXVIII. Fig. 12. 
 
 Char. Fronds terrestrial, saccate, firm, densely tufted, 
 plaited and icrinkled, of a roundish fojin. CeWs arranged 
 171 fours, crowded. 
 
 Ulva crispa Lightfoot. Grev. Alg. Brit. p. 175.; Hook. 
 Brit. Flor. vol. ii. p. 312.; Harvey, in Manual, p. 171. 
 Ulva furfuracca Horncastle. Grev. Crypt, t. 265. ; 
 Hook. Brit. Flor. p. 312. ; Harvey, in Manual, p. 171. ; 
 E. B. t. 2754. 
 
 Ilab. On damp ground, rocks, thatched roofs , &c. ; very 
 common, winter and spring ; rocks near the sea : Appin : 
 Captain Carmichael. On the walls of King's College, 
 Cambridge : Rev. 31. J. Berhclcg. Several [)laccs near 
 
298 ULVACEiE. 
 
 Limerick : W. H. Harvey. Near Ballycastle : Mr. D. 
 Bloore. Roger's Tower on Castle an Dinas, near Gul- 
 vall ; and Bosigran Castle, near JNIorvali ; in both places 
 on granite : Mr. Borrer. Dublin Bay : Bin Moore. 
 On damp shaded Avails, on the ground ; frequent, near 
 Tunbridge Wells : Mr. Jenner. Walls of Chesterton 
 church, near Cambridge : Rev. Prof. Henslow. 
 
 Having carefully examined numerous specimens which have 
 been sent me under the names of Ulva crispa and Ulva fur- 
 furacea, and not being able to detect the slightest difference in 
 the microscopic characters of these, I do not hesitate to unite 
 the two supposed species. 
 
 The specific denominations of crispa and furfuracea are 
 both well expressive of the appearance of this species : the cells 
 are densely crowded together in the frond, so as indeed to 
 leave very narrow interspaces between the groups of cells, 
 which are usually composed each of about sixteen cells, 
 disposed in fours, and which from the compression one against 
 the other are rendered somewhat angular. The different 
 groups of cells are not disposed usually in linear series. 
 
 3. Ulva calophylla Spreng. 
 
 Plate LXXVII. Fig. 1. 
 
 Char. Frond densely tufted, plane, linear, ligulate, attenu- 
 ated at base, often stipitate, longitudinally striate, each 
 stria marked with a seizes of bi-quaternate granules. 
 
 Hook. Brit. Flor. vol. ii. p. 312. Bangia coloyhylla Carm., 
 
 in Grev. Crypt. Fl., t. 220. 
 Hob. On damp stones, rocks, &c. ; Lismore Island, 
 
 Appin : Captain Carmichael. Near Limerick : JV. H. 
 
 Harvey. Dublin : Mr. Moore and Dr. G. J. Allman. 
 
 North of Ireland : 3Ir. D. 3Ioore. Oswestry : Bev. J. 
 
 Sahvey. 
 
 " This forms a bright green thin stratum. Frond minute, 
 three or four lines long, linear, strap- shaped, obtuse, tapering 
 at base, or suddenly contracted into a cylindrical stipes, much 
 
MERISMOPEDIA. 299 
 
 waved and curled, very variable in breadth. Granules qua- 
 ternate, closely covering the frond, set in longitudinal lines, of 
 which two or more (sometimes half a dozen) form the breadth 
 of the frond ; interstices coloui'lcss." — Ilarv. 
 
 Kiitzing makes a new genus for this species under the 
 name of Prasiola. 
 
 4. Ulva binalis Hass. 
 
 Char. Cells large^ in hoos. 
 
 I have not studied this species with sufficient attention to 
 pronounce decidedly whether it is distinct or not ; the ar- 
 rangement of the granules by twos woidd seem, however, to 
 be remarkable, and to render it very probable that it really is 
 so. Tliis species would appear to be referred to in the fol- 
 lowing remarks of Vaucher's "Hist, des Conf." p. 238. "It 
 is not impossible but that other species of freshwater Ulva 
 exist independently of those which I have described. I have 
 myself met with some otiiers Avhich have appeared to me to be 
 different from the two first ; one in particular, the grains of 
 which were disposed two by two, and not four by four ; but I 
 pass them by under silence, because I am not assured whether 
 they are species or only varieties." 
 
 40. IMEEISMOPEDIA. 
 
 Char. Frond increasing by spontaneous division, laminar, 
 quadrangular. 
 
 Derivation. From /Mspia-fxa?, a division, and ttsZlov, a 
 fetter or chain. 
 
 1. Merismopedia punctata Meyen. 
 
 Plate LXXXIV. Fig. 6. 
 
 Char. " Green, corpuscles imhedded in a crystalline 7nem- 
 brane, and nearly the j|^ of a millimetre in size, polypary, 
 quadrangular , flattened, sometimes twice as broad as long, 
 equalling from the jV to ^ of a millimetre, and containing 
 sixteen simple corpuscles, cither binary or quaternary.'''' — 
 Ehr. 
 
300 ULVACEiE. 
 
 Merisviopedia punctata Jenner, in Fl. of Tunbridge Wells. 
 
 Gonium tranquillum Ehi\, Die Infus. p. 57. t. iii. f. 3. 
 Hab. Ashdown Forest, Cold Bath Spring, &c. : Mr. 
 
 Jenner. 
 
 I am not at all acquainted with this pretty production ; it 
 doubtless, however, belongs to the family of Ulvacece, and 
 my Ulva binalis may possibly be identical with it. 
 
 41. TETRASPOKA Link. 
 
 Char. Frond either tubular, injlatcd, or Jlat, gelatinous. 
 Cells mostly arranged in fours. 
 Derivation. From rsrpa, four, and crTropa, a seed ; in allu- 
 sion to the arrangement of the cells. 
 
 This genus seems to me to be wholly unnecessary : it ought 
 either to merge into Ulva, or else several species now asso- 
 ciated with that genus should be removed from it and placed 
 in Tetraspora. All the characters of the genus Tetraspora 
 may be found in one or other species of Ulva, and especially 
 that of the quaternate arrangement of the granules, or perhaps 
 more strictly speaking, the cells, from which the generic de- 
 nomination is derived. 
 
 1. Tetraspora lubrica Ag. 
 Plate LXXVIII. Fig. 10. 
 Cha7\ " Frond quite simple, tubular, sub gelatinous, waved 
 and serrated,^^ 
 Harv. in Hook. Brit. Flor. vol. ii. p. 313. ; Harvey, in 
 
 Manual, p. 176. 
 Hab. Hellesdon, Norfolk : Sir IF. J. Hooker. Appin : 
 Captain Carmichael Castlemartyr, Cork : Miss Ball. 
 Malahide : Mr. Moore. Aberdeen : Dr. Dickie. In an 
 old quarry above Cromlyn Bog, Swansea : J. IV. Gutch. 
 Tunbridge Wells ; Mr. Jenner. 
 The freshwater Ulvacea have not as yet been studied with 
 
TETRASPORA. 301 
 
 the attention which they require. I do not feel at all cer- 
 tain that either this species, or Tet. gelatinosa are really dis- 
 tinct from Ulva bullosa : at all events, it is certain that in 
 Ulva bullosa in its young state the frond is saccate or tubular, 
 and the granules arranged in fours : neither can any difference 
 be detected in the size of the cells in these sujjposed species : 
 all which circumstances lead to the suspicion that they are 
 but states of the same production. If the observation of 
 Vaucher be correct that the granules or cells undgrgo an in- 
 crease of size at the period of the complete developement of the 
 frond, and just before it passes to decay, then it would seem 
 that no certain character can be derived from their size, unless 
 the condition of the species as to age be likewise ascertained. 
 The frond of T. lubrica is stated to be larger than in the 
 following species, less gelatinous, with a more distinct mem- 
 brane and of a deeper colour. The tube finally ruptures, and 
 becomes membranaceous, with an Irregular outline. 
 
 2. Tetraspora gelatinosa Desv. 
 Char. Frond ovate, injiated, and very gelatinous. 
 Hook. Br. Fl. p. 313. ; Harv. in Manual, p. 176. 
 Hab. In freshwater streams attached to aquatic plants ; 
 Newcross, Killarney : TV. H. Harvey. Botanic Garden, 
 Belfast : Dr. Drummond. Malahlde : Mr. Moore. 
 
 "Frond exceedingly lubricous and gelatinous, but firm, 
 dehcately waved, and plaited, of an oval outline. Sporules 
 bright green, or arranged in fours or scattered." — Harv. 
 
 3. Tetraspora flava Hass. 
 Plate LXXVIII. Fig. 11. 
 Char. Frond ivhen dried yellowish. Cells very minute. 
 Hah. Rocky rivulet, co. Antrim ; 3Ir. Moore. 
 
 This species at all events would appear to be distinct, the 
 cells being two or tlu-ee times smaller than those of tlie two 
 preceding Tetrasporce. 
 
302 ULVACE^. 
 
 42. HYDRURUS A(/. 
 Char, Frond gelatinous, cylindrical, branched, solid, filled 
 with scattered, oviform, bright green gramdes. 
 Derivation. From uScop, water, and ovpa, a tail. 
 
 1. Htdrurus Ducluzelii Ag. 
 Plate LXXVII. Fig. 3. 
 Char. Frond very gelatinous, branched, plumose. 
 
 Ag. Consp. Crit. Diat. p. 27. Batrachospermum Myosurus 
 Ducluz. Palmella Myosurus Jjjngh., Dan. t. 68.; Harv. 
 in ISIanual, p. 180. 
 
 Hab. In alpine rivuletSj on stones, &c. In the river 
 Walkam, near Tavistock : 3Ir. Ralfs. Meary, Devon : 
 Rev. W, S. Hore. 
 
 " Root scutate, blackish, rather hard. Fronds clustered, 
 solid, very gelatinous, 2 — 6 inches long or more, 2 — 4 lines 
 in diameter, cylindrical, freely waving in the water, atte- 
 nuated towards the apex, branched ; branches scattered, 
 alternate, elongate, slender, beset with other more slender, 
 short ramuli. Gelatinous mass peUucid, viscid, colourless 
 under the microscope, without apparent margin, unless as 
 the granules imbedded within its substance indicate such ; 
 these are globose, green, formed in the stem and primary 
 branches, most densely set in the ramuli, especially towards 
 the margin. Colour of the recent frond brownish-olive, or 
 dark brown, in drying, green ; of the granules both recent 
 and drj^, green. 
 
 " The odour, in a recent state, is very offensive, and as 
 Lyngbye remarks, only to be submitted to by an algologist. 
 In a dry state it shi'inks much, and most closely adheres to 
 paper. Having only seen this very interesting plant in a dry 
 state, I have thought it better to copy the above description 
 from Lyngbye. Our specimens, so far as they can be exa- 
 mined, well agree with his figure. The affinities of the genus 
 are doubtful. By Agardh it is now placed near Schizonema, 
 
ENTEKOMOIIPHA. 303 
 
 to which its offensive smell certainly fillies it. But the form 
 and appearance of the granules are so totally unlike the frus- 
 tules of any diatomaceous plant, that, for the present at 
 least, I retain it near Palmdla, to Avhich it seems to me 
 about as much allied as ChcEtophora cndiviafolia to the shape- 
 less species of that genus. If a true diatomaceous plant, it 
 ought, as Agardh suggests, to form the type of a new series, 
 of which, perhaps, our Cymhella Icetevirens might represent 
 the lowest form." — Harv. 
 
 There is not the least question but that the Hydrurus 
 Ducluzelii is not a diatomaceous plant, and it is equally clear 
 that it is an undoubted member of the family of the Ulvacece, 
 in some measure connecting Ulva with Enteromorpha. The 
 granules are oviform, precisely resemble zoospores, with 
 which in function it is difficult to conceive that they are not 
 identical, the thin being ti-ansparent. 
 
 Section ii. 
 Frond reticulate. 
 
 43. ENTEROMOEPHA Lijih 
 
 Char. Frond tubular, hollow, membranaceous, and of a reti- 
 culate structure. Fructification consisting of three or 
 four granules aggregated in the reticulations. 
 
 Derivation. From svrspov, the entrail, and fxopcpt], a form 
 or appearance. 
 
 1. Enteromokpha INTESTINALIS Liyili. 
 Plate LXXVIL Fig. 2. 
 Char. Fronds elongated, simple, inflated, of ten floating . 
 Grev. Alg. Brit. p. 179.; Wyatt, Alg. Dar. No. SO. 
 E. B. 2756. ; Harv. in Hook. Brit. Flor. p. 313. ; et in 
 INIauual, p. 174. E. lacustris Hassall, in Trans, of Lin- 
 naean Society. 
 Hab. In ditches. Common, summer and autumn. 
 
304 ULVACE^. 
 
 " Fronds often two feet or more long, and from a line to 
 two or three inches in diameter, tapering at base, at first 
 fixed by a minute root, afterwards detached and freely floating, 
 inflated, variously waved or curled, of a full green colour, 
 fading to yellowish, and finally white." — Harv. 
 
 " In the earliest stage of their developement, the tapering 
 filaments consist of a single series of cells placed end to end. 
 Each of these cells afterwards becomes bisected by a longitu- 
 dinal line, and other lines subsequently appear, so that the 
 original cells are ultimately divided into several, each of 
 which, in its tmn, enlarges, and is in like manner divided. 
 From the continued growth and unlimited division of the 
 cells the filaments increase to an indefinite size, soon lose 
 their original confervoid character, present a reticulated ap- 
 pearance, and, instead of being attenuated, become cylindrical 
 and hollow. 
 
 " In each cell or articulation of the filaments, and when 
 these are not thicker than a horse hair, a dark central nucleus 
 is gi-adually developed, which, there can be no doubt, under- 
 goes repeated division in the same manner as the reproductive 
 globules of the UIvcb. These nuclei often germinate while 
 still enclosed within the cells in which they were developed, 
 and while the parent filament retains all its freshness and 
 vigour, and give rise to the pointed and tapering filaments 
 first described ; which, in this state, after the rupture of the 
 parent cells, and while their bases are fixed within them, one 
 filament in each, bear a strong resemblance to a parasitic 
 Conferva. 
 
 " This developement, division and growth of cells and repro- 
 ductive bodies, appears to be going on continually and suc- 
 cessively, so that most specimens of the plant present ex- 
 amples of each different stage of its formation. 
 
 " The Enteromorpha intestinalis would appear to have a 
 twofold relation to the ConfervcB in its young articulated 
 filaments, and to the Ulva in its reproduction from globules 
 wliich undergo repeated division. The tautology of the 
 specific name is objectionable, and that of lacustris might be 
 substituted for it." — Hoss. 
 
BOTKYDUM. 305 
 
 44. BOTRYDUM Wall 
 Char. " Plant a spherical vesicular receptacle, filled xoith a 
 watery fluid, dehiscent at the apex, terminating below in 
 radiating tufts of fibres." — Grev. 
 Derivation. From ^oTpvs, a bunch of grapes, which the 
 clustered fronds somewhat resemble. 
 
 1. BOTRYDDM GRANULATUM Grev. 
 
 Plate LXXVII. Fig. 5. 
 
 Grev. Alg. Brit. p. 196. t. 19.; Hooker's Brit. Flor. 321. 
 Tremella gramdata, E. B. t. 234. Conf. midticapsularis 
 Dillw. t. 71.? Gongoseira clavata? Klitzing, Phy. Gen. 
 p. 281. 
 
 Hab. On damp clayey ground, dried up ponds, &c. 
 Common. 
 
 " Fronds minute, densely clustered on the surface of the 
 ground, spreading in patches. Vesicle containing a watery- 
 fluid, in which a few granules are sometimes found. In dry 
 weather the upper part of the vesicle collapses, when they 
 become cup-shaped." — Harv, 
 
 Kiitzlng I believe has not included In his " Phycologia Ge- 
 neralls " the genus Botrydium : he has constituted, however, 
 a new genus for the Conf. muUicapsularis of Dillw., under 
 the name of Gongoseira. This genus he places amongst the 
 Protoncmcce, which is probably the position which this curious 
 production ought to occupy. 
 
 " Thus natural history blends with primitive tradition and record, 
 affording to our faith a basis of previous probability, -with evidence on 
 every side, in our paths, our fields, our gardens, our woods; in cultiva- 
 tion and in the desert ; in every fibre, roof, stem, leaf, flower, or fruit, 
 demonstrating the omnipotent all-sustaining omnipreseut God." — J. S. 
 Duncan's Botanical Theology. 
 
306 
 
 Fmi. XVII. PALMELLE^. 
 
 Cha}\ Frond consisting of a gelatinous colourless fluid, in 
 which are immersed numerous globules, containing the co- 
 lou7'ing matter. 
 
 45. PALMELLA Lgngb. 
 
 Char. " Frond mucous, indefinite, enclosing hyaline globules, 
 in which the colouring substance, continuous, and never 
 granular, is situated. Granules first evolved in the 
 mucous substratum of the frond, at length constituting new 
 globules.'"' — ISIeneghini. 
 Derivation. From TraXfxos, vibration ; in allusion to the 
 gelatinous nature of the frond. 
 
 " This genus differs from all the other genera of Nosto- 
 chinecB, especially In its frond, which, from the beginning, is 
 indefinite. In other species the frond preserves its defined 
 form during the entire course of its existence, or at least in the 
 beginning describes a certain form with peculiar limits. But 
 in this, the frond never can possess a definite form, on account 
 of the nature of its generation and evolution ; for the globules 
 living in the mucous substratum of the frond, otherwise 
 very similar to those of other Nostochinece, differ as much 
 as possible from all others, in the fact of the colouring matter 
 in them never becoming granular, and that, because the gra- 
 nules from which new globules proceed are neither evolved 
 nor undergo evolution In the interior of the maternal globules ; 
 for these are either altogether resolved into mucus, or pour 
 out the mucous substance which they contain, which sub- 
 stance not being covered with an involucre, is indefinitely 
 diffused, and is circumscribed only by external circum- 
 stances. But in this mucoslty minute punctated points or 
 granules appear, which little by little are evolved, and at 
 length attain to the dimensions of the parent globules. The 
 
PALJIELLA. 307 
 
 form, therefore, of the frond is necessarily indefinite. By- 
 reason of the absence of the vesicles nourished in the interior 
 of the larger globules, the material included in the globules 
 is altogether continuous, fluid, and never granular. At length, 
 when effused, the presence of dots or minute granules dis- 
 persed through the mucous substratum afford distinct cha- 
 racters whereby the genus may be easily distinguished by 
 microscopic examination. 
 
 In the genus Palmella^ as limited by himself, Meneghini 
 describes two species, PalmeUa cruenta and P. montana. 
 The first of these ISIeneghini takes for the type of his genus 
 PalmeUa, and to this only do his observations in any mea- 
 sure apply. The other species seems to me to be of a nature 
 altogether different, indeed scarcely congeneric. In P. cruenta 
 the grains or cells are loosely scattered through the mucous 
 matrix, and their contents are usually, as Meneghini describes 
 them, uniform and homogeneous. In P. montana, P. Ralfiii, 
 P. virescens, and P. griimosa, the cells are collected into little 
 clusters, and their contents are nucleated. ISIeneghini, there- 
 fore, would not appear to have studied the second species of 
 his genus P. montana, which, as well as the other species 
 PalmeUa Ralfsii, P. virescens, and P. grumosa, ought, in all 
 probability, to be included in a distinct genus. PalmeUa cruenta y 
 on the one side, evidently bears a close relation to Protococcus 
 nivalis, from which indeed it principally differs in the fact 
 of the globules being distinctly immersed in gelatine, Avhile 
 in P. nivalis they are free. P. montana, Sec., on the other 
 hand, exhibits a relation almost as close to Hamatococcus, from 
 which genus it differs in the same manner as Protococcus 
 nivalis and PalmeUa cruenta differ. The globules of HcBma- 
 tococcus sanguineus exhibit the same nucleated a])pearance as 
 do those of P. montana, P. Ralfsii, &c. 
 
 X 2 
 
308 PALMELLEiE. 
 
 1. Palmella ceuenta Ag. 
 Plate LXXX. Fig. 5. 
 
 Char. Frond indefinite, crustaceous, expanded, blood-red, 
 tuberculate, filled loith subangular hyaline globules, and 
 '' very minute punctiform scattered granules.^'' 
 Tremella omenta, E. Bot. t. 1800.; Grev. Crypt. Flor. 
 p. 205. ; Hook. Brit. Flor. vol. ii. p. 396. ; Harv. in 
 Manual, p. 179. 
 Hab. On clamp walls, chiefly such as are whitewashed ; 
 often in cellars. Glasgow : Sir W. J. Hooker. On 
 damp walls near the ground at Mayfield and elsewhere, 
 frequent : Mr. Jenner. 
 " The red spots in the beginning irregularly orbicular, 
 quickly becoming confluent, attached to earthy particles, to 
 stones, and other extraneous substances, form a Avidely ex- 
 panded crust, which, on the application of moisture, swells 
 up, and then especially resembles coagulated blood. By 
 drought their young frond grows dusky and disappears ; but 
 more evolved, it dries up, and is more intensely coloured ; it 
 cracks, curls up, and falls in pieces. Rainy weather con- 
 tinuing, and other Algoz being evolved amongst it, especially 
 Oscillatoria autumnalis and Microcystis atrovircns, it be- 
 comes green, and at length black. If the crust be kept 
 immersed some hours in Avater, it swims on the surface 
 like a thin pellicle. A morsel of this subjected to the 
 microscope presents hyaline globules, subangular, and adorned 
 with a faint carneous tint, which are so closely heaped toge- 
 ther, that at first sight they appear to form a cellular mem- 
 brane. Nevertheless they are not joined by any adherence, 
 as is evident from the fact that they recede from each other 
 under the object glass itself with the slightest pressure. The 
 mucous, colourless substratum and punctiform granula or 
 lesser globules, more intensely coloured, then come into sight. 
 Moreover, a fragment of the frond itself, first submerged in 
 water, submitted to microscopic examination, manifests the 
 same organs, though less appressed, and the mucous sub- 
 stratum, endowed with more consistence, is detected." 
 
SOROSPORA. 309 
 
 46. SOROSPORA //as5. 
 
 Char. Cells nucleated, associated in clusters. 
 
 Derivation. From (Tcopos, a cluster or mass, and airopa, a 
 seed. 
 
 1. SOROSPORA MONTANA Hass. 
 
 Plate LXXIX. Fig. 1. 
 
 Char. Frond between coriaceoiis and gelatinous, irregular, 
 much and variously lobed, curled, dark jjurple. Granules 
 . crowded, in clusters composed of six or eight granules each. 
 P. alpicola Lyngb., Hydroph. p. 2067. ap. 69. Ulva mon- 
 tana Light., Scot. Flor. p. 973. Ulva montaiia Hud- 
 son, Flor. Ang. p. Q52. Ulva montana Withering, Ar- 
 rangement of Br. PI. vol. iv. p. 122. ; Smith, E. B. 
 t. 2193.; Harv. in Hook. Br. Flora, p. 396., also in 
 Manual, p. 179. 
 
 Hah. On mosses and lichens on the summits of rocks. On 
 the mountains of the Isle of Skye, and west coast of 
 Scotland; GlenCateol: Dr. M'Culloch. Lying on the 
 ground but not attached to it, in stony moist places on 
 Goat Fell, Arran : Sir W. J. Hooker. 
 
 According to Lightfoot, this is the " Mountain Dulse " of 
 the Scotch. 
 
 " On the mountains of Arran this lies unattached among 
 loose wet stones, covering them in a straggling manner to a 
 considerable extent. Each frond is an inch or an inch and a 
 half in diameter, flattish, somewhat orbicular, between co- 
 riaceous and gelatinous ; when dry almost horny, of a deep 
 but dull purple colour, much lobed and curled, like some Gy- 
 rophora;, filled with crowded clusters of granules, which, if 
 minutely examined, are found to be arranged mostly in fours." 
 ~ Hook. 
 
310 PALMELLE^. 
 
 2. SoROSPORA Ralfsii Hass. 
 Plate LXXIX. Fig. 3. 
 
 Char. Frond minute, thin, gelatinous, hyaline, somewhat areo- 
 late; each areola containing 2 — 8 large, globose, blood-red 
 granules. 
 Palmella Ralfsii Harv., in Manual, p. 179. 
 Hah. Spreading over mosses on Cader Idris : Mr. Ralfs. 
 
 "Fronds a few lines in diameter, gelatinous, somewhat 
 areolate, or as if composed of numerous small yesicles massed 
 together, each of which contains 2 — 4 or eight large blood- 
 red granules, which are much larger and of a far deeper colour 
 than those of P. montanaP — Harv. 
 
 In the specimens which I have examined of this species, 
 the granules in each cluster have been usually not less than 
 six or eight, and between the clusters faint divisions of the 
 mucous matrix may be discerned, which increases still further 
 the resemblance which this and the preceding plant bear to 
 HcBmatococcus, and especially Hcsm. sanguineus. 
 
 3. Sorospora virescens Hass. 
 
 Plate LXXVIII. Fig. 8. a. 
 
 Char. Frond green. Cells in clusters, nucleated, globose. 
 
 Of this species I have seen but a very small fi-agment ; 
 there can be no doubt, however, I think, of its distinctness : 
 each cell is imbedded in a distinct cavity of the mucous 
 matrix, the outline of which may be distinctly traced subse- 
 quent to the removal of the cells. 
 
 4. Sorospora grumosa Hass. 
 
 Plate LXXX. Fig. 7. 
 
 Char. Frond icidely expanded, clotted, brick-red, fioating. 
 Globides usually hinate, globose, hlood-red, and surrounded 
 by a narrow pellucid limbus, occasionally aggregated. 
 
COCCOCHLORIS. 311 
 
 Palmella grumosa Carm., MS. P. grumosa Harv., in- 
 Manual, p. 180. 
 
 Hah. On a rock at the sea side in a small cavity filled 
 with rain water at Appln : Captain CarmichaeL West 
 of Ireland: M'Colla. 
 
 This species would appear to be somewhat anomalous, 
 agreeing, in the fact of the globules being immersed in a dis- 
 tinct gelatinous matrix, with the genns Pahnella, and according 
 with Hoamatococcus in the circumstance of these being sur- 
 rounded with a pellucid margin, and also in its reproduction : 
 not, however, that it is ascertained that the reproduction of 
 S. grumosa is really distinct from HcBmatococcus. It there- 
 fore connects these two genera closely with each other. In 
 diying the brick-red colour of the frond changes to a dirty 
 green, with a slight degree of gloss upon its surface. 
 
 47. COCCOCHLORIS Spre7ig. 
 
 Char. Frond mucous, definite, at a later period often effused, 
 in which are imbedded the globules, Jilled with matter mostly 
 green and granular, to be converted into vesicles replete 
 with globules, and producing neto fronds. 
 Derivation. From kokkos, a berry, and ■^oopo?, green. 
 
 The following observations on Coccochloris, Avhich would 
 appear to be a tolerably well established genus, occur in ISIene- 
 ghini's " Monographia Nostochinearum," pp. 57, 58. 
 
 " Globuli, in substrate mucoso nidulantes, matcrie granulari 
 fareiuntur. Non taraen omnes ad evectiorem evolutionem 
 perveniunt ; nonnuUi enim tantum majorcs dimcnsiones con- 
 sequuutur, eorumque interior substantia in distinctos globuloa 
 confirmatur ; globuli hujusmodi propagatioue inscrvientes vcl 
 ad superficiem tantum frondis reperiuntur vel inordinatas ct 
 sparsje in quacumque frondis regione evolvuntur. In primo 
 illo casu a fronde matricali facile extricantur et totidem 
 novas frondes constituunt quibus ita definita forma semper 
 inest; in sccundo vero primordia ilia novarum frondiuni a 
 
312 PALMELLE^. 
 
 mucoso frondis matricalis substrate obvoluta et impedlta 
 extrlcari nequeunt et ibidem evolvuntur usque dmn tandem 
 eodem dissolute et evanido libere dissemiuantur. In primis 
 illis frons, tota vita perdurante, semper definita remanet : in 
 his primum definita quidem est, sed ab initio usque efFunditur 
 et dissolvitur. Differunt itaque Coccochlorides a Pahnellis, in 
 CO quod granula in sinu globulorum ipsorum gignuntur et 
 evolvuntur, proptereaque frons definita hie necesse inest, dum 
 illfe eodem necesse carent; et quamquam serins in multis 
 quoque Coccocliloribus frons ipsa eflfundatur, origine tamen 
 summopere ab ilia Pahnellarum diflfert. Ita ut PalmellcB Proto- 
 coccos in muco indefinite nidulantes representant, sic Cocco- 
 chlorides a Chloroaoccis in fronde mucosa definita inclusis 
 eiformata3 dici possunt." 
 
 1. COCCOCHLORIS TROTUBERANS Sjjreiig. 
 
 Plate LXXVI. Fig. 7., and PI. LXXXII. Figs. 6, 1, 
 8, 9, 10. 
 
 Char. Fronds green, gelatinous, soft, irregularly lobed, spread- 
 ing, conjluent. Globules elliptical, generally more obscure 
 toioards the centre, Yesicles of vai-ious sizes, spherical or 
 elliptical, constantly surrounded icith a diap)hanous margin. 
 Ulva protuberans Smith, E. B. t. 2583. Palmella protu- 
 berans Grev., Flor. Edin. p. 323. ; Crypt. Fl. t. 243. f. 1. 
 Palmella protuberans Ag., Sjst. p. 14. ; Hook. Br. Fl. 
 vol. ii. p. 396. ; Harv. in INIanual, p. 176. Coccochloris 
 protuberans Spreng., Syst. Veg. vol. iv. p. 373. Palmo- 
 gloea protuberans Kiitzing, Phy. Gen. p. 176. 
 Hab. Sussex, spring to autumn : 3fr. Borrer. Camsle 
 Glen, near Glasgow : Sir W. J. Hooker and Dr. Greville. 
 Pentland Hills : Dr. Greville. On the ground at Crow- 
 borough Warren : Mr. Jenner. Co. Wicklow : Mr. 
 Moore. 
 
 " The fronds in the beginning roundish, of very variable 
 magnitude, quickly run into a mass more or less extensive, 
 investing surrounding bodies or spreading over the naked soil. 
 
COCCOCHLORIS. 313 
 
 Its substance, in the beginning Avatcry and pellucid, becomes 
 at a later period firmer and more intensely green. The frond 
 itself, subjected to the microscope, differs very considerably 
 in the different states of its developement. When it is green 
 and firm, the globules scarcely vary at all in dimensions, but 
 generally stand at the one hundred and twenty-fifth part of 
 a millimetre in the greatest diameter, and their form always 
 oblong, varies from elliptical to irregularly angular. Their 
 interior substance appears obscurely granular, and is always 
 more opaque in the centre. The vesicles are variable in form 
 and magnitude ; the smaller are mostly spherical, the larger 
 elliptical, all constantly surrounded by a hyaline border. 
 The smallest of all only differ from the other globules in 
 their spherical form and diaphanous margin ; and the most 
 nevertheless attain the fiftieth j^art of a millimetre in dia- 
 meter, and the largest have the twentieth part in their 
 greatest diameter. The larger these are, the more manifestly 
 granular is the structure of the interior substance: when 
 enclosed they scarcely equal the thousandth part of a milli- 
 metre. The diaphanous margin is equally manifest both in 
 the smaller and greater vesicles, and preserves the same pro- 
 portion. In the more delicate fronds, and those having less 
 consistence, being almost watery, the mass itself is constituted 
 of a colourless thin mucus, in which the oblong cylindrico- 
 elliptical, or rarely spherical globules, reaching from the two 
 hundredth to the one hundredth part of a millimetre in their 
 greatest diameter, hyaline or diluted green, scattered here and 
 there, appear, with areola3 intensely green, presenting a definite 
 suborbicular, or but irregular form, constituted of firmer and 
 more intensely coloured mucus, and filled with subrotund 
 globules, varying in diameter, from the thousandth to the 
 two hundredth part of a millimetre, and surrounded with a 
 narrow diaphanous margin. Intermediate forms are some- 
 times noticed, in which the mass itself, more diluted and 
 watery, gradually disappears, and the green areolae increased 
 in size, and at length confluent, assume finally tlie characters 
 of the older fronds." — Menegh. 
 
314 PALMELLE^. 
 
 2. COCCOCHLORIS MUSCICOLA Menegh. 
 
 Plate LXXVIII. Figs. 3 a. 3 b. 
 
 Char. " Frond mucous, indefinite, very slender, investing mosses, 
 blackish green ; the smallest globules perfectly spherical, 
 green, generally gei'minate. Vesicles elliptical, the larger 
 entirely filled with lesser globules, and not surrounded with 
 any margin.^'' 
 
 P. hyalina, B. muscicola Harv., Manual, p. 177. 
 
 Hah. Aberdeen : Dr. Dickie. 
 
 "The mucous pellicle, blackish green, shining, covers exten- 
 sively mosses, and at the same time includes with our Cocco- 
 chloris, Oscillatoria autumnalis aild Nostoc lichenoideum, the 
 Coccochloris globules scarcely measuring the three-thousandth 
 part of a millimetre, imbedded in a soft and easily yielding 
 mucus, in which are mixed, scattered elliptical vesKjles, varying 
 in dimensions from the hundredth to the twenty-iifth part 
 of a millemetre, entirely filled with smaller globules closely 
 heaped together. The vesicles themselves are seen to be 
 constituted of a very slender membrane, which embraces them, 
 but not presenting a diaphanous margin, and which by lacera- 
 tion is scarcely to be perceived : when the membrane has been 
 ruptured, the contents of the globules escape into irregular 
 angular heaps. The vesicle from which the globules have 
 proceeded is not apparent : this however is certain, that the 
 globules are not surrounded by any peculiar membrane. 
 
 " The vesicles effused into irregular areolae resemble the 
 beginnings of new fronds, which, evolved in the mucous matrix, 
 and quickly becoming confluent, form a mucous pellicle. Hence 
 the frond is said to be indefinite, although, in the beginning, 
 as in all other species of this genus, it is definite. This spe- 
 cies agrees in habit with Coccochloris protuberans, but in 
 structure and microscopic characters it exhibits greater afli- 
 nity with Coccochloris parietalis, as will be shewn hereafter." 
 
 In drying, it leaves but a mere stain upon the paper, most 
 evident at the margins of the frond. 
 
coccocnLORis. 315 
 
 3. COCCOCHLORIS HYALINA Mcncgh. 
 
 Plate LXXVIII. Figs. 2 a. 2 b. 
 
 Char. Frond gelatinous, cylindrical or globose, solitary, sub- 
 hyaline ; internal globules globose, very minute, green. 
 Palmella hyalina Lyngb. ; Grev. Scot. Ciypt. Fl. t. 247.; 
 Harv. in Hook. Brit. Flor. p. 397. ; Harv. in Manual, 
 p. 177. 
 
 Hah. Bogs at Fisher's Castle, Tunbridge Wells : Mr. 
 Jenner. 
 
 Lyngbye describes this species as follows : — " Mass gela- 
 tinous, cylindrical, solitary, solid, floating on the surface of 
 water, an inch or two long, colour commonly Avatery, pel- 
 lucid, except as regards that which is OAving to the internal 
 granules, which are of a deUcate green colour. Substance in 
 the highest degree lubricous, adheres, in drying, to paper." 
 Brebisson, however, states that it attains to the remarkable 
 size of one or two feet in length, and from six to eight inches 
 in thickness. 
 
 " Specimens communicated liberally by CI. Brebisson 
 and Lenormond are five inches long, and although closely 
 adherent to paper, yet manifest greater solidity of the suiDcr- 
 ficial stratum over the internal substance. For being lacer- 
 ated by compression, they exhibit the interior eifused sub- 
 stance hyaline, and the exterior pellicle more intensely 
 coloured and opaque, and divided into uTcgular fragments. 
 In the interior substance uniform, very minute globules are 
 imbedded, scarcely measuring the two thousandth part of a 
 millemetre ; but the exterior pellicle is constituted of globules 
 somewhat larger, covering a diameter of the two hundred and 
 fiftieth part of a millimetre. In which oblong vesicles, alto- 
 gether filled witli minute globules, from the twentieth to tlie 
 twenty-fifth part of a millimetre long, are mixed." 
 
 What appears to me to be at least a variety of this 
 species was sent to me by the Kev. INI. J. Berkeley. The 
 fronds were globose, but smaller and less solid than those of 
 C. hyalina in its usual state, and the globules larger. See 
 
 PI. LXXVIII. fiff. 5. 
 
316 PALMELLEiE. 
 
 4. COCCOCHLORIS DEPRESSA Menegh. 
 
 Plate LXXVIII. Figs. 4 a. 4 b. 
 
 Char. " Fronds subhemispherical, depressed, green. Granules 
 globose or irregular.''^ — Berk. 
 
 Palmella depressa Berk., Glean, p. 19. t. 5. f. 4.; Harv. 
 in Manual, p. 178. 
 
 Hah. Growing on an old pump at Cotterstock, North- 
 amptonshire, and constantly moistened by the dripping 
 of the spout. 
 
 " The irregular granules, some of them larger than others, 
 and many being agglomerated together, and comprehended 
 in a common integument, as depicted by the author, have 
 led to this generic collocation of this species. The comparison 
 also which the author of this species instituted with the 
 Palmella terminalis Ag. appears to sustain this opinion." — 
 Menegh. Wiien dried the frond is destitute of gloss. 
 
 5. COCCOCHLORIS MOOREANA Hass. 
 
 Plate LXXVIII. Figs. 1 a. 1 b. 
 
 Char. Fronds large, globose or lobed, of a rich dark ceru- 
 ginous green colour, unaltered in drying, and of firm 
 substance. Globules oval, small, tolerably uniform in size 
 and shape. 
 
 Palmella Mooreana Harv., in Manual, p. 178. 
 
 Hab. In a boggy hole at Shane's Castle, the seat of Lord 
 O'Neill, near Lough Neagh : Mr. D. Moore. 
 
 " The fronds are of an irregular globose form, about an 
 inch in diameter, tuberculated, and inclining to become hollow 
 in the centre when old, at which time it floats on the sur- 
 the colour is dark green, and the substance firm, resem- 
 bling that of an animal's liver." — Moore's MS. The rich 
 jeruginous green colour of this species, resembling that of 
 many Oscillatorice, affords a character whereby at once this 
 species may be distinguished from all its congeners. The 
 
COCCOCHLORIS. 317 
 
 fronds adhere closely to paper, present considerable gloss, 
 and retain the freshness and depth of their colouring when 
 dried. 
 
 " I have much pleasure in ascribing It to Its acute dis- 
 coverer Mr. D. Moore, curator of the Royal Dublin Society's 
 Botanic Garden, who has added so many Interesting plants 
 to the Irish Flora." — Harv. 
 
 Having only had the opportunity of examining dried spe- 
 cimens, I am not able to give the measurements of the 
 globules and vesicles ; I have, however, been able to ascertain 
 sufficient of the species to render It quite certain that the 
 reference to the genvis Coccochloris Is correct. The same re- 
 mark applies to the other species which I have placed in 
 that genus. 
 
 6. Coccochloris rivularis Hass. 
 
 Plate LXXVIII. Figs. 6 a. b. 
 
 Char. Fronds liemispherical, tuberculoses often confluent^ 
 bright green when recent, turning to broivn in drying. 
 Globules small, globose, scattered. 
 
 Pahnella 7'ivularis Carm., MS. P. rivularis Harv., In Hook. 
 
 Brit. Flor. p. 397. ; Harv. in Manual, p. 177. 
 Hab. In a mountain streamlet, attached to rocks and 
 
 stones, Aj^pln: Captain Carmichael. 
 
 " Fronds one fourth or half an Inch In diameter, hemi- 
 spherical, tubercular, firmly adhering, sometimes coherlno- 
 Into a broad crust. Gramdes small, globular, scattered. 
 Colour vivid green. It bears a striking resemblance to Chce- 
 tophora tuberculosa.'^ — Carm. MSS. In drying it shi'iuks 
 considerably, and fides to dirty brown.* 
 
 * In a specimen -which I have lately examined of this species, I dis- 
 tinctly perceived divisions in the mucous substance ; a certain number, 
 usually two, of the granules, as in the genus Ilcematococais, being invested 
 with a separate portion of the general substance. It is probable that this 
 structure belongs to all the species of the genus, and possibly of Ulva also. 
 
318 PALMELLE^. 
 
 7. CoccocHLORis Grevillei Hass. 
 
 Plate LXXVIII. Figs. 7 a. b. 8. 
 
 Char. Fronds minute^ densely croicded, globose or someiohat 
 lobed, green, decidedly gelatinous. 
 a Granules elliptical. 
 /? Granules small, globose. 
 
 7 Frond smaller, more hyaline, and loith larger globose 
 granules. 
 
 Berk. Glean. Br. Alg. p. 16. t. 5. f. 1. ; Harv. in Manual, 
 p. 177. Palmella botryoides Grev., Crypt. Fl. t. 243. f. 
 2.; Harv. Hook. Brit. Fl. 1. c. p. 396. — /S. P. botnjoides 
 Lyngb., Dan. p. 205. —7 Berk., Glean, t. 5. f. 2. 
 
 Hab. On heathy places, moist situations, frequent : 7 on 
 decaying stems of Asparagus officinalis ; in a hotbed ; 
 Rev. M. J. Berkeley. 
 
 " Fronds minute, densely crowded, globose, green, com- 
 posed of pale green jeUy, in which are numerous darker gra- 
 nules, elliptic in var. a ; in var. /3 globose, and accompanied 
 with smaller globose granules, collected more or less into 
 little rounded heaps, the longest of which are of the size of 
 the larger granules. After it has been dried, the jelly is 
 nearly colourless, and the granules are scattered, and all of 
 the same size." — Rev. M. J. Berkeley. 
 
 It is evident from the preceding description that more than 
 one sj)ecies is included under the name of Palmella Grevillei. 
 
 Note. I have since paid further attention to the subject of the division 
 of the mucous matrix into vesicles or cysts in Coccocldoris, and I now 
 find that this structure is to be met vrith only in certain species of the 
 genus, and that it cannot be detected in any of the species figured in this 
 work. The species, therefore, with the frond thus divided, connect Cocco- 
 clilor is -vi'iih. Hcematococcus., and scarcely differ from those of the latter genus. 
 
 It is still probable that the structure really does belong to all the Coc- 
 cochlorides, but that the extreme delicacy of the organization of some of 
 the species prevents its detection. Ramifying throughout the substance 
 of the fronds of all the species may be observed numerous slender 
 branched tubes, which may either be parasitic growth, or else form part 
 of the organization of the fronds ; and in the latter case they may be pre- 
 sumed to be connected with respiration. 
 
319 
 
 Fam. XVIII. PROTOCOCCE^. 
 
 Char. Stratum indefinite, frinhle, formed by an aggregation 
 of distinct globules, ichich, not being immersed in gelatine, 
 and not enclosed by a common investing membrane, are 
 readily separable from each other on the application of 
 moisture. 
 
 48. BOTRIDINA Breb. 
 
 Char. " Frond gelatinous, globose, at a later period entirely 
 constituted of vesicles enclosing granules ; at length the 
 internal vesicles being absorbed, and the outer cellular 
 membrane defined, including granules imbedded in mu- 
 cus.'''' 
 Derivation. The diminutive of ^orpvs, a bunch. 
 
 Obs. " CI. Brebisson humanissimis literis observationes 
 suas commuuicavit, quibus innixus novum hoc genus pro- 
 posuit, has ipsas maxima pro parte et nos ipsi veritate 
 apprime rcsijondentes invenimus. In hoc tamen nostra differt 
 sententia, quod granula secundum CI. Brebisson in alveolis 
 tantum periphericis sita, nobis contra in alveolis cum peri- 
 phericis tum interioribus initio nidulari videantur, sed alve- 
 olis sine vesiculis illis interioribus serins resorptis, et peri- 
 phericis tantum iisdemque vacuis, membrana efFormatur 
 globules jam evolutos et propagatione aptos muco obvolutos 
 includens. Nomen a CI. Brebisson propositum, legibua 
 glossologiai non omnino concisum, delere ausi non sumus." 
 — 3Ieneghini. 
 
 This genus resembles somewhat in structure the compound 
 pollen granules of many plants. 
 
 Note. The Anacystis furfuracea IMeiiegli., a production very different 
 from tbe Palmella furfuracea Berk., -witb which Mencgliini supposed it 
 identical, and one coming near to Botridina, is a British Alga. I have 
 more than once met with it. 
 
320 PROTOCOCCEyE. 
 
 1. BOTRIDINA VULGARIS Breh. in lit. 
 
 Plate LXXXI. Fig. 2. 
 
 Char. " Fronds smalls spherical, aggregated, often conjluent, 
 green, solid, with minute globose or suhangular globules.'''' 
 " Nostoc botryoides Ag., Syn. p. 135. Palmella botryoides 
 Lyng., Hydrop. p. 205. No. 6.; Ag. Syst. p. 14. No. 5.; 
 Grev. Scot. Crypt. Fl. t. 5. No. 243. ? P. Grevillei 
 Berk., Glean, vol. i. p. 16. t. 5. f. \.—'i''' — Meneghini. 
 Botridina vulgaris Meneghini, in Monograph. Nosto- 
 chinearum. 
 
 " The fronds of various sizes, rarely surpassing the head 
 of a pin, of a subspherical form, aggregated in considerable 
 quantity, cover the stems of mosses with a pulverulent 
 blackish green stratum, which Agardli first well delineated. 
 The granules in the beginning solitary, here and there affixed 
 subspherical or slightly angular, scarcely equal in their 
 greatest diameter the five hundredth part of a millimetre ; 
 gradually they increase in size, and when they have arrived 
 at the two hundredth part of a millimetre, they manifest an 
 internal granular substance ; at a later period having acquired 
 a form exactly spherical, the internal substance is seen ag- 
 gregated or collected into the centre, and the granules sur- 
 rounded by a pellucid mai'gin. Again they increase in size, and 
 the interior granules are seen converted into vesicles filled with 
 lesser granules. These vesicles increased in number and mag- 
 nitude, the greatest dimensions of the frond being attained, 
 occupy its entire substance, and at length the diaphanous 
 margin disaj^pears. The whole frond is then constituted of 
 vesicles closely heaped together, and enclosing in the centre 
 granules. The primitive membrane, enclosing in its midst 
 the interwoven or cellular structure, is so closely united with 
 the peripheral stratum of vesicles, that it can in no Avay be 
 separated from it. The last developement having been ac- 
 complished, the peripheral stratum of vesicles altogether looses 
 its granules : whether these disappear by absorption, or escape 
 outwardly, I have never been able to perceive. In this man- 
 
n.'EMATOCOCCUS. 321 
 
 ner the frond again obtains a diaphanous margin, but different 
 from that with which in the beginning it was surrounded." — 
 Mencgh. 
 
 49. H^MATOCOCCUS Ag. 
 
 Char. Cells spherical or oval, of various sizes, each invested 
 with one or more concentric vesicles or membranes, mul- 
 tiplied either by division or by granules formed within the 
 parent cells. 
 Derivation. From aljia, blood, and kokko?, a berry. 
 
 Agardh has evidently included in his genus Hccmatococcus 
 productions gcnerically distinct; as, for example, //. sanguineus 
 and H(Bm. or projjerly Protococcus nivalis : he therefore would 
 appear not to have entertained any precise ideas in reference 
 to his genus beyond the fact of the contents of the cells of 
 some of the species being of a red colour. Meneghini in the 
 memoir so often referred to, limits the genus Hcumatococcus 
 to one species, the H. nivalis of Agardh, a production which 
 assuredly does not differ even specifically from the Proto- 
 coccus nivalis of the same author, and constitutes a ncAV genus 
 Microcystis for the reception of //. sanguineris and its allies, 
 the adoption of which, as //. yiivalis Ag. cannot be allowed 
 to remain in that genus, is rendered unnecessary. 
 
 Of the two terms Ha^matococcus and Microcystis, the latter 
 is by far the more applicable, the former being in some de- 
 gree objectionable, inasmuch as it is founded on the colour of 
 the globules, a colour confined to a limited number of the 
 species of the genus. ISIeneghini thus defines his genus 
 Microcystis : — 
 
 " Frond mucous ; in the beginning definite, at a later period 
 effused, including globules clothed in vesicles and multi- 
 plied by a quaternary division or by gramdcs evolved 
 within, constituting so many new fronds." 
 
 " Each globule, in the same way as those of the Pleurococci, 
 shrinks from its involucre, and then appears to be clothed 
 with its proper vesicle. A process of this kind is frequently 
 
 Y 
 
322 PROTOCOCCE.E. 
 
 rejieated, and hence arise so many concentric vesicles en- 
 closing the small globule in the centre. 
 
 " Frequently the globule, having shrunk from its proper 
 envelope, is divided into half, and each half, having shrunk 
 from its investing vesicle, again is divided into two parts, and 
 this occurs many times in succession. At length, the vesicles 
 being torn or converted into mucus and absorbed, the glo- 
 bules themselves formed by division are poured out into the 
 common mucous substratum. At other times the primitive 
 globules, or more frequently the internal substance of the 
 second, the usual division being suspended, passes into very 
 minute granules, and the involucre of the globule itself con- 
 verted into mucous substance, gives birth in the same man- 
 ner to new globules. The frond in the beginning indeed 
 definite, nevertheless speedily becomes confluent, and inde- 
 finitely expanded. This genus, therefore, differs only from 
 Coccochloris in the division of the globules, wliich likewise 
 manifests an affinity to JRleurococcus.'^ — 3Iene(j1iini. 
 
 The species included by me in the genus Hcematococcus 
 admit of division into three subgenera. They embrace also 
 the genera Microcystis and Pleurococcus of Mencghini, to dis- 
 tinguish which genera I can find no satisfactory character. 
 
 First Subgenus. — Globules appendaged, that is, each termi- 
 nates or is imbedded in the extremity of a distinct mucous 
 prolongation, the mass of the pla?it being formed princi- 
 pally of these mucous prolongations. 
 The term Ouracoccus might be applied to the species of this 
 
 subgenus. 
 
 a. Mucous prolongation /jiZazw. Granules invested with a 
 single vesicle. 
 
 1. H^BiATOcoccus Allmani Hass. 
 Plate LXXX. Fig. 3. 
 
 Char. Globules elliptical, large, blood-red, surrounded by a 
 single diaphanous margin. 
 
H^MATOCOCCUS. 323 
 
 Hah. Dropping Well, Knarcsborough : Prof. G. J. Allman. 
 
 The globules of this species resemble in size and form 
 those of Coccochloris murorum, a species which might indeed 
 be referred to the genus Hcematococcus, it differing from 
 H(2m. Albnani only in colour, and In so far as I can ascer- 
 tain, the absence of the mucous appendages. If these ever be 
 present in Coccochloris murorum, then there can be no doubt 
 of the generic identity of the two plants. 
 
 Not being able to find that this plant has as yet been re- 
 corded, I have great pleasure in naming it after my friend 
 Dr. Allman, from whom alone I have received the plant. The 
 specimens sent, although very fine, were not altogether free 
 from admixture, being mixed up with examples of Ham. 
 Hookeriana. It was on an examination of these specimens 
 that I first discovered the mucous appendages, of Avhich I 
 immediately aj^prlscd Dr. Allman, who wrote to me as fol- 
 lows : — *' ]\Iauy thanks for your Information. Your ob- 
 servation on the structure of the AlgcR I sent you is most 
 interesting. Though I distinctly enough detected a peculiar 
 organization in the gelatinous flesh in which the capsules of 
 the Alga with red granules are Imbedded, I saw nothing of 
 the singular arrangement you mention. Your observation Is 
 certainly most interesting and original. I am longing to exa- 
 mine the Alga, now that you have directed my attention to 
 the curious fact you mention." The granules vary much in 
 size in this as well as in all other species of the genus Hcema- 
 tococcus. The Hcem. sanguineus of Kiitzing may possibly be 
 referrible to this, or perhaps more probably to the Ham. crxjp- 
 tophiluy as it is described as having elliptical granules. 
 
 2. H^MATOCOCCUS MURORUM Hass. 
 
 Plate LXXXI. Fig. 4. 
 
 Char. Granules elliptical, aruginous green, free, surrounded 
 hy a hand, pellucid limhus. 
 Coccochlorum murorum Grev., Scot. Crypt. Fl. t. G. No. 
 325. Microcystis mellea ? JNIenegh., loc. cit. t. xii. fig. 2. 
 Hah. Scotland : Dr. Grcvillc. Ireland : Mr. Moore. 
 T 2 
 
324 PROTOCOCCE^. 
 
 The cells of this species precisely resemble those of //. 
 Allmani in form and size, the only difference being that of 
 colour, and the absence of the mucous elongations. It ought, 
 assuredly, to be regarded as congeneric with H. Allmani. 
 In a specimen from the herbarium of Sir W. J. Hooker, the 
 granules were not, as in other specimens which I have exa- 
 mined, exactly cylindrical, but somewhat pointed at one 
 extremity. 
 
 May 14. 1845. — I have just detected mucous appendages 
 in this species similar to those of //. Allmani. 
 
 3. H^MATOCOCCUS CRYPTOPHILA Hass. 
 
 Plate LXXX. Fig. 1. 
 Char. Granules Mood-red^ small, usually oval. 
 Palmella ? cryptophila Carm., MS. cum icone. Hcema- 
 
 tococcus sanguineus, in part, Harv. in Manual, p. 181. 
 
 Hah. On a stalactitic incrustation lining the vault of a 
 
 cavern in a quartz rock, Appin : Captain Carmicliael. 
 
 This forms wide patches, externally of a brick-red colour, 
 but within whitish, breaking up easily into the numerous 
 separate portions of which each mass is formed. The reason 
 of the red colour being confined to the external surface of 
 the crust results from the structure and mode of develope- 
 ment of the species of this genus. The colour resides alone 
 in the granules : these terminate the superior extremity of 
 the mucous prolongations, which are colourless, and arranged 
 almost entirely side by side. The granules or cells are several 
 times smaller than in H. Allmani. 
 
 b. Mucous prolongations transversely corrugated or ringed. 
 Granules 1 — 2 m each cell, spherical. Vesicles luanerous. 
 
 4. H^MATOCOCCUS INSIGNIS Hass. 
 Plate LXXX. Figs. 6 a. 6 b. 
 Char. Granules very large, spherical, blood-red. 
 Hah. England. 
 
niEMATOCOCCUS. 325 
 
 This very fine species I have never met with In any con- 
 siderable quantity. Scattered Isolated globules I have fre- 
 quently met with, and these occasionally attaclied to a closely 
 corrugated or ringed mucous appendage. Each gloljule Is 
 usually suiTounded by a single vesicle or ring : In some 
 globules, however, there are as many as four or five en- 
 closing vesicles. 
 
 5. H^MATOCOCCUS HOOKERIANA Berk, and Hass. 
 Plate LXXX. Fig. 4. 
 
 Char. Granules vei-j/ small, spherical, blood red, suri-ounded 
 by one or more investing membranes or vesicles. 
 Hab. On a clialk cliff at JNIundley, Norfolk : Sir W. J. 
 Hooker. Dropping Well, Knaresborough : Dr. Alhna?i. 
 
 Shortly after noticing this species In beautiful condition, 
 mixed up with H. Allmani, but which had altogether escaped 
 the notice of Dr. Allman, I received a dried specimen of 
 this plant, accompanied by a description and remarks on the 
 ringed organization of the mucous appendages from the Eev. 
 M. J. Berkeley, to whom It had been communicated for exa- 
 mination by Sir W. J. Hooker. Specimens of //. Allniayii and 
 IT. Hookcriana were then sent to Mr. Berkeley, who satisfied 
 himself of the Identity of Dr. Allmau's specimen with that 
 transmitted to him by Sir William Plooker. The only differ- 
 ence between the specimens collected In habitats so widely 
 different was, that In the former the transverse corrugation 
 of the. sheath was the more conspicuous. 
 
 The Rev. ]\I. J. Berkeley, in his first letter, thus speaks of 
 it: — " I have just received the enclosed from Sir W. J. Hooker. 
 It does not agree with any of jMeneghinl's species of Micro- 
 cystis. There Is a very curious appearance In some parts as 
 if the old vesicles were chained together." In a second com- 
 munication, ]Mr. Berkeley adds — " I have not had time to ex- 
 amine your Alga till to-day : it is certainly the same as Sir W. 
 Hooker's, but far finer ; the threads are three or four times 
 as long. I still fancy my theory, as to their origin, is right." 
 Y 3 
 
326 PROTOCOCCE^. 
 
 Second Subgenus. — Mucous appendage wanting. Granules 
 one, two, or four, in each cell. 
 
 Obs. It is possible that subsequent research may prove 
 that one or more of the species of this section should be re- 
 ferred to the first subgenus. 
 
 a. Investing vesicles numerous. 
 
 6. H.EMATOCOCCUS RUPESTRIS Hoss. 
 
 Plate LXXXII. Fig. 1. 
 
 Char. Granules spherical, olive green, single, sometimes binate, 
 very small, each enclosed in several distinct enveloping 
 vesicles. 
 
 Palmella rupestris Lyngb., Hydroph. p. 207. t. 69. D. 
 P. rupestris Ag., Syst. p. 13. Microcystis rupestris Kiitz., 
 Linnjea, p. 374. No. 9. Microhaloa rupestris Kiitzing, 
 Phycologia Generalise p. 169.; Harv. in Hook. Br. Flora, 
 ii. 397. ; also in Manual, p. 178. ; Meneghini loc. cit. 
 
 Hob. On moist overhanging cliffs, Appin : Caj?t. Car- 
 michael. Aberdeen: Dr. Dickie. On moist conglo- 
 merate sandstone caves near Cushendall, co. Antrim : 
 M?'. JSIoore. 
 
 " Frond, hyaline, gelatinous, yellowish green, easily broken 
 \\]), about an inch in diameter, shapeless, rough; pellucid, 
 more dense in the centre and elevated ; when dried, collapsed ; 
 blackish, cartilaginous, fragile. Subjected to the micro- 
 scope, it appears constituted of hyaline subspherical vesicles, 
 enclosing yellowish green, spherical or slightly oblong glo- 
 bules, usually undivided. Solitary globules, magnified Avith 
 glasses less powerful, are seen free and naked ; by means of a 
 more powerful microscope, almost all are perceived to be 
 clothed with a proper cyst, larger vesicles enclose smaller, 
 and the whole frond appears areolated, the hollow areolae con- 
 taining solitary or binate globules. The vesicles, general as 
 well as partial, duplex, trijilex, or multiplex, and that without 
 
H^BIATOCOCCUS. 327 
 
 any perceptible order, commonly present concentric circles, 
 generally approximated, evident to the light. But the quater- 
 nary type, both in the distribution of the vesicles and glo- 
 bules, is generally preserved. The diameter of the globules 
 is constant at the two hundredth part of a millimetre ; that of 
 the vesicles varies from the hundredth to the twenty-fifth part 
 of a millimetre. 
 
 " At a more advanced period of growth, some globules be- 
 come thicker, and manifestly include a granular substance, 
 the partial vesicles at the same time becoming dissolved, and 
 disappearing. Towards the circumference of the frond are 
 often noticed globose, elliptical, or irregularly lobed areolae, 
 which are seen to be gelatinous, and all filled with very mi- 
 nute granules scarcely the fiftieth part of a millimetre in size. 
 It appears, therefore, that each one of the larger vesicles, the 
 partial vesicles included by it being absorbed, the globules 
 having been converted into granules, is changed into a new 
 frond. As often as a fragment of the frond is compressed Idc- 
 tween plates of glass, the oblong gelatinous bodies enclosing 
 very small granules, which we regard as new and incipient 
 fronds, and which are always present in great abundance, are 
 lacerated, their contents poured forth, and they then cover 
 the other parts with the thin mucus with which they are 
 themselves enveloped; and from this C. Kiitzing appears 
 to have asserted that the vesicles were enfolded, the green 
 stratum enclosing very minute granules. It is yet remark- 
 able that the multiplied and concentric vesicles escaped the 
 celebrated Kiitzing and the acute Lyngbye." — Mencgldni. 
 
 7. HiEMATOCOCCUS GRANOSUS Harv. 
 
 Plate LXXXI. Fig. 6. 
 
 Char. Crust tmdehj spreading^ granulated, pale green. Cells 
 polymorphous, formed of two or three vesicles, and each 
 containing one, two, or four green, large, elliptical Qvawulcs 
 loith distinct hyaline borders. 
 
328 PKOTOCOCCE^. 
 
 Palmclla granosa Berk., Glean. Brit. Alg. il. p. 19. Mi- 
 ci'ocystis granosa Menegliini, 1. c. p. 85. 
 
 Hab. Growing in great abundance on sub-immersed 
 Hypnum stellatum, in the bogs bordering on Wliittlesea 
 Mere, summer : Rev. M. J. Berkeley, Aberdeen : 
 D7\ Dickie. Broadwater Forest : Mi\ Jenner. 
 
 " Pale green, or when j)reserved in the herbarium, with a 
 pale brownish tint. Growing in large masses of no certain or 
 distinct form, but broken into many angular faces, having a 
 very granulated apj)earance, and crumbling beneath the fin- 
 gers. The whole plant is made up of sub-elliptic, hyaline, 
 colourless, jelly-like bags, containing from two to four green 
 elliptical granules, which in some lights appear as if sur- 
 rounded with a pellucid border." — Berk. 
 
 Meneghini makes the following remarks on this fine spe- 
 cies : " Hie auctor mouet speciem banc prajter colorem Hcb- 
 matococco sanguineo Ag. simillimam esse ; et ejusdem affini- 
 tate cum Palmella riipestris animadvertens limites generum 
 Hasmatococcus et Palmella iucertos esse demonstrat, summo 
 nempe acumine novi generis Microcystis instituendi necessi- 
 tatem prjesenserat." 
 
 b. Usually hut one investing membrane or vesicle. 
 
 * Granules yro7?i one to eight. 
 
 8. Hj<:matococcus alpestris Hass. 
 Plate LXXXI. Fig. 3. 
 
 Chor. Globules of very variable size, often large, rarely 
 concentric, containing one, two, four, or eight, but usitally 
 two or four small, spherical, dark green granules. 
 Pleurococcus glomeratus ? Menegh., loc. cit. t. v. f. 2. 
 Hab. Wales : Sir W. J. Hooker. 
 
 On looking over the splendid collection of Algce forming 
 part of the herbarium of Sir W. J. Hooker, I noticed a 
 
HiEMATOCOCCUS. 329 
 
 specimen of a, dark olive compact substance two inches in ex- 
 tent, marked Trcmella. This, on examining with the micro- 
 scope, I soon ascertained to belong to the present genus, of 
 which it forms a remarkable species — one remarkable for the 
 size of the vesicles, the smallness of the enclosed granules, and 
 for the absence in general of concentric rings or vesicles. 
 
 ** Granules mostly numerous in each cell 
 9. H^MATOCOCCUS SANGUINEUS Af/. 
 
 Plate LXXIX. Fig. 2. 
 
 Char. Smaller cells spherical, containing usually one or two 
 granules; larger, often angular, and filled ivith numer- 
 ous blood-red, circular, and ?iucleated granules. 
 Hcematococcus sanguineus Ag., Icon. Alg. Europ. Xo. xxiv. 
 Palmella ? sangidnea Ag., Syst. p. 15. Hcem. sangui- 
 neus, in part, liar v. Manual, p. 181. - 
 - Hah. On shady rocks at Tobermorey in Mull : JV. II. 
 Harvey. 
 
 Mr. Harvey in his " Manual " has included in his HcEmato- 
 coccus sanguineus two species, the one being the Palmella? 
 cryptophila of Cnrmichael, the other, in all probability, the 
 true H. sanguineus, a production which Avould seem to be as 
 .rare as it is strikingly beautiful, it only having as yet been 
 discovered in one locality by Mr. Harvey, to whom I am in- 
 debted for the specimen from which my figure is taken. The 
 smaller cells are quite ■ spherical, and contain but a single 
 blood-red granule, a wide pellucid border produced by the 
 thickness of the single vesicle which encloses it surrounding 
 the granule : the larger attain a very considerable size, arc 
 mostly angular, and include a very considerable number of 
 large spherical granules, each of Avhich is occasionally sur- 
 rounded by a transparent vesicle, in which state each separate 
 granule is to be regarded as a distinct young frond enclosed 
 in the parent cell. 
 
330 PROTOCOCCEiE, 
 
 10. H^MATOCOCCUS PRUSTULOSUS Harv. 
 
 Plate LXXXL Fig. 1. 
 
 Char. Crust xcidely spreading, friahUi dark grey. Cells large, 
 roundish, containing numerous, very minute, scattered 
 granules. 
 
 Palmella frustulosa Carm., MSS. cum icone. Hoimatococ- 
 cus frustulosus Harv., in Hook. Br. Fl. p. 395. ; also in 
 Manual, p. 181. 
 
 Hah. On irrigated cliffs, perennial, Appin : Cajjt. Car- 
 michael. 
 
 Capt. Carmicliael thus briefly describes this fine species : — 
 " It occurs in the form of a greyish black fragmentary scurf 
 On the slightest pressure it separates into Corpuscles of va- 
 rious forms, but mostly spherical, hyaline : under the micro- 
 scope, surrounded by a membranous envelope, and including 
 several granules." 
 
 The granules are very minute, spherical, not usually sur- 
 rounded by vesicles, and very numerous, the larger cells en- 
 closing as many as one or two hundred granules. 
 
 11. H^MATOCOCCUS ARENARIUS jFZaS5. 
 
 Plate LXXVI. Fig. 10. 
 
 Char. Cells spherical, rather small, containing spherical 
 green granules, varying in number from one to ten, but 
 usually there are Jive or six. 
 Hah. Tunbridge Wells Common : Mr. Jenner. 
 
 This species approaches rather closely to the preceding, but 
 yet may be easily distinguished from it. The cells or fronds 
 of //. arenarius are much smaller, contain fewer granules, 
 although these are larger than those of H. frustulosus. 
 
 *** Ov^mwXQS, frequently binate or quaternate. 
 
 The granules in all the species of the genus Hcematococcus 
 are increased by division, the division not usually extending 
 
H^MATOCOCCUS. 331 
 
 to the outer membrane. The cells, the yoimgest of all, con- 
 tain but a single granule : as the developement proceeds, this 
 becomes divided into two other granules, and these are again 
 subdivided, and so on the process of multiijlication proceeds, 
 in some cases, as in H. sanguiyieiis and H. frustulosus, to a 
 much greater extent than in other si^ecies. 
 
 12. HiEMATOCOCCUS BINALIS Hass. 
 
 Plate LXXXII. Fig. 2. 
 
 Char. Cells large, elliptical, green, each containing mostly two 
 seyni- elliptical granules. 
 Pleurococcus thermalis 9 Menegh., loc. cit. t. iv. fig. 3. 
 Hab. Cheshunt : A. H. H. Aberdeen, mixed up with 
 otlier Alga3 : Dr. Dickie. 
 
 This species is very distinct. Some of the cells contain 
 but a single granule, others two, and these are by far the 
 most numerous ; others again, four granules. The species I 
 suspect is by no means uncommon. 
 
 It is not unlikely that this Is an appendaged species. 
 
 13. H^MATOCOCCUS FURFTJRACEUS Has$. 
 
 Plate LXXXII. Fig. 4. 
 
 Char. Cells small, spherical, or somewhat angulated. Granules 
 often associated in pairs. 
 
 Palmella furfuracca Berk., Glean. Alg. p. 18. t. 5. f. 3. P. 
 furfur acea Harv., in Manual, p. 178. 
 
 Hah. Forming a thin mealy stratum of a light yellowish 
 green, on the walls of a large frame at jMilton, North- 
 amptonshire : Rev. M. J. Berheleij. Limestone rocks, 
 CO. Antrim : Mr. Moore. 
 
 " Fronds aggregate, diffuse, irregular, granulated, rather 
 rigid, under the knife, falling down into a mass of minute 
 
332 PROTOCOCCE^. 
 
 more or less rounded granules with scarcely any appearance 
 of jelly." — i?e;-A. 
 
 The Anacystis furfuracea would appear to be an entirely 
 different plant. 
 
 14. H^MATOCOCCUS LIVIDUS Hass. 
 
 Plate LXXXII. Fig. 5. 
 
 Char. Crust of an indefinite extent, and livid colour. Granules 
 spherical, green, small, solitary or binate, and frequent, 
 quaternate, the quaternate granules being contained in 
 spherical cysts. 
 
 Pahnella livida Carm., in Grev. Flor. Edin. P. livida 
 Harv., in Manual, p. 178. Microcystis livida Meneghini, 
 Monographia Nostochinearum Italicarum, p. 74, 5. 
 
 Hab. " On overhanging cliffs, covering them to an indefi- 
 nite extent Avith a dirty black scurf: " Captain Car- 
 michael. Found on limestone rocks near Poilballintrea, 
 CO. Antrim : D. Moore. 
 
 The solitary and binate granules which constitute by far 
 the greatest portion of the plant are not enclosed in cysts, 
 and therefore do not appear to be surrounded by a trans- 
 parent limb or border. The granules however when asso- 
 ciated in pairs or multiples of that number are always enclosed 
 in a distinct cyst or vesicle, and occasionally it happens in 
 this as in other species of this division of the genus Hamato- 
 coccus, that each of the contained granules is also furnished 
 with a distinct envelope. 
 
 Mr. Moore writes of this species : — " This singular substance 
 covers the overhanging limestone rocks to a great extent, 
 sometimes as much as several hundred yards together. When 
 fresh, it looks like a blackish brown, gelatinous substance, 
 giving the rocks on which it grows the appearance of being 
 covered with pitch. On places where it becomes dry by 
 exposure to the sun, it is very friable, and on being touched 
 crumbles down to a powder. Under the glass it is found to 
 
HiEMATOCOCCUS. 333 
 
 be composed of excessively minute granules, pellucid in the 
 centre with darker edges. Is it a Pabnella?''' 
 
 15. HiEMATOCOCCUS yERUGINOSUS Hass. 
 
 Plate LXXXII. Fig. 3. 
 
 Char. Stratum (Bruginous greeuy firm. Granules minute, 
 mostly solitary, and not enclosed in cysts, somewhat angular, 
 occasionally in their ultimate devclopement associated in 
 pairs or 77udtiples of that nwnber and contained in a 
 globose vesicle. 
 
 Palmella cBruginosa Carm., MS. 
 
 Hab. Appin : Captain Carmichael. 
 
 Of this species, remarkable for the richness of its colour, I 
 found a specimen in the herbarium of Sir W. J. Hooker. In 
 its microscopic character, it resembles somewhat H. lividus, 
 but is altogether a smaller plant. 
 
 16. Il/EMATOCOCCUS THERIACUS Hass. 
 
 Plate LXXVIII. Fig. 9. 
 
 Char. Granules excessively minute, mostly solitary and sphe- 
 rical, but occasionally enclosed in cysts. 
 Hab. Eievaulx Abbey, Yorkshire : Dr. Allman. 
 
 This is the most minute species of the genus. Dr. All- 
 man, who alone has noticed it, compares its appearance to 
 that of inspissated syrup. 
 
 17. H^.MATOCOCCUS VULGARIS ZTrt^^. 
 
 Plate LXXXI. Fig. 5. 
 
 'Char* Cells many-cysted, of various sizes and forms. Gra- 
 nules angular, numerous in each cell, often repeatedly 
 divided into fours. 
 
 Pleurococcus vulgaris IMenegh., Consp. p. 20. Chloi-ococcum 
 vidgare Grev., Scot. Cryjit. Fl. vol. iv. No. 2G2. 
 
334 PROTOCOCCE^. 
 
 Hah. On walls, trees, &c., Cheshunt : A. H. H. Appin : 
 Captain Carmichaeh 
 
 Although this species Is somewhat peculiar in its deve- 
 lopement, not the slightest necessity exists for its removal 
 from the many-cysted species of the genus Hoimatococcus. It 
 is impossible to make too rigid an examination and analysis 
 of plants of this order, but the utmost care is required in 
 forming a right estimate of the value of the differences dis- 
 closed by a rigorous examination, for if every small difference 
 be too highly regarded, we shall soon have genera as nu- 
 merous as species. The figure given in this work is chiefly 
 taken from that of Meneghini's " jMonograpliia." 
 
 18. HiEMATOCOCCUS MICROSPORUS Hass. 
 
 Plate LXXVI. Fig. 8. 
 
 Char. Cells angular, adherent to each other, and each occu- 
 pied with usually four minute slightly oval green granules. 
 Hah. Uckfield Sandrocks, Sussex : Mr. Jenner. 
 
 This is a distinct enough little species. I have only seen 
 the specimens of Mr. Jenner, who sent it me as " Palmclla 
 protuherans.''^ The granules are always enclosed in cells, 
 which are strongly adherent to each other, and never sepa- 
 rate. 
 
 19. H^MATOCOCCUS MINUTISSIMUS ^fl55. 
 
 Plate LXXVI. Fig. 9. 
 
 Char. Globules spheincal. Granules excessively minute, 
 green. 
 
 Hah. Mixed up with H. furfuraceus. Ireland : Mr, 
 Moore. 
 
 The granules in this species are even smaller than those of 
 H(Bm. microsporus, and are much more numerous in each 
 cell than in tliat species. 
 
PROTOCOCCUS. 335 
 
 50. PROTOCOCCUS Ag. 
 
 Char. Plant consisting of aggregated, naked globules, filled 
 vfith minute granules, and sessile on a gelatinous trans- 
 parent mass. 
 
 Derivation. From irpwros, first or primary, and kokkos, 
 fruit ; from its elementary organization. 
 
 " Agarclh states that the globules of his Protococcus are 
 perfectly simple, or consist merely of a hyaline cellule en- 
 closing an uniform coloured mass, and he regards our British 
 plant as a different species, belonging to Ilamatococcus. 
 Having minutely examined a specimen from Agardh himself, 
 submitted to me for that purpose by Dr. Greville, and find- 
 ing exactly the same compound structure as in our Britisli 
 specimens, I do not hesitate to pronounce the two plants 
 identical." — Harv, 
 
 1. Protococcus nivalis Ag. 
 Plate LXXX. Fig. 2. 
 
 Char. Globules exactly spherical, very minute, fine purple- 
 red. Gelatinous mass pale, spreading. 
 Grev. Crypt. Fl. t. 231. ; Ag. Je. Alg. Europ. t. 21., and 
 Hoim. Grcvillii Ag., 1. c. t. 23.; Harv. 1. c. p. 395. Pal- 
 mella nivalis Hook., in Parry's 2nd Voy. App. Uredo 
 nivalis Bauer, in Journ. of Science and Arts, vol. vii. 
 p. 222. t. 6. 
 
 Hab, On the borders of the lake of Lismore, spreading 
 over decaying leaves, &c. : but in greater perfection ou 
 the calcareous rocks, within the reach of occasional in- 
 undation : Captain Carmichael. Near Miltown jNIalbay, 
 on schist ; Limerick, on limestone ; and about Dublin 
 on granite. In most cases slightly imuidatcd. — IV. H. 
 Harvey. 
 
 This curious little plant, -which, under the name of Bed 
 Snow, has excited so much interest among botanists, is usu- 
 
336 PROTOCOCCE^. 
 
 ally found in this country in the form of a thin, stain-like 
 stratum on the surface of rocks, or investing decayed vege- 
 table substances with a purplish crust. On examination 
 under the microscope, it is found to be composed of innu- 
 mei'able spherical bodies, seated upon a gelatinous substra- 
 tum. The globules are of various sizes, probably depending 
 upon age. At first they are furnished with a wide pellucid 
 border, and contain a deep red homogeneous mass. As they 
 increase in size, this border gradually becomes narrower, and 
 at length altogether disappears, while the internal mass, 
 Avhich at first was simple, becomes broken into numerous 
 distinct granules or seeds, which are finally discharged. Red 
 snow, we are informed by Professor Agardh in his interesting 
 memoir on the Protococcus *, was first observed by Dr. Saus- 
 sure in the year 1760, on Mount Beven, in Switzerland, and 
 subsequently so frequently among the Alps, that he was sur- 
 prised how such a phenomenon should have escaped the 
 attention of other travellers, especially Scheuchzer. Ra- 
 mond found red snow on the Pyrenees, and the botanist 
 fSommerfeldt in Norway. At the beginning of the century 
 it was noticed on several of the mountains of Italy, along 
 the Apennines; and in March, 1808, the whole country 
 round Cadore, Belluno, and Feltre was covered in one night 
 to the depth of twenty centimetres with a rose-coloured snow, 
 a pure Avliite snow having fallen before and after, so that the 
 coloured snow formed an intermediate stratum. The same 
 fact is recorded at the same time in several other Italian 
 localities. Still i^ed snoio excited little attention among 
 botanists, and had not obtained a place in our scientific 
 arrangements until Captain Koss discovered it in Bafiin's 
 Bay, covering tracts of some miles in extent, and penetrating 
 in some places to the depth of ten or twelve feet. The spe- 
 cimens brought home by this celebrated traveller were sub- 
 mitted to Mr. Bauer and ]\Ir. Brown, to be examined 
 
 * IsTova Acta Pliys. ]\Ied. Academia3 Cas. Leop Car. Nat. Cuv. vol xii. 
 p. 737. Translated in Grev. Crypt; Fl. vol. iv. sub. t. 231. 
 
PROTOCOCCUS. 337 
 
 botanically, the latter of whom, with liis usual acuteness, 
 decided that It was " Algarum genus?? Confervls siinpli- 
 cibus et Tremellas cruentaa quodanimodo affine ? ? " The 
 " local liabitation " thus assigned, has been acknowledged 
 by all succeeding botanists ; and Agardh has completed its 
 history by giving it "a name." — Harv. 
 
 " It is to be observed, that the same wisdom -which ordained the vege- 
 table creation for the use of feeding and healing the body, hath applied 
 it also to a moral and intellectual use, for the enlarging of our ideas, and 
 the enlightening of our understandings. It joins its voice in the universal 
 chorus of all created things, and to the ear of reason celebrates the -n-is- 
 dom of the Almighty Creator. As the heavens, from day to day and from 
 night unto night, declai-e the glory of God, so do the productions of the 
 earth ; all trees and herbs, in their places and seasons, speak the same lan- 
 guage, from the climates of the north to the torrid regions of the south, 
 and from winter to spring and the harvest. Happiest of all is he, who, 
 having cultivated herbs and trees, and studied their vii'tues, and applied 
 them for his own and for the common benefit, rises from thence to a 
 contemplation of the great Parent of good, whom he sees and adores in 
 these his glorious works. The world cannot shew us a more exalted 
 character than that of a truly religious philosopher, who delights to turn 
 all things to the gloi-y of God ; who from the objects of his sight derives 
 improvement to his mind, and in the glass of things temporal sees the 
 image of things eternal. Let a man have all the world can give him, he 
 is still miserable, if he has a grovelling, unlettered, undevout mind ; let 
 him have his gardens, his fields, his woods, and his lawns, for grandeur, 
 ornament, plenty, and gratification, while at the same time God is not in 
 all his thoughts ; and let another have neither field nor garden ; let him 
 only look at nature with an enlightened mind ; a mind which can see and 
 adore the Creator in his works ; can consider them as demonstrations of 
 his power, his wisdom, his goodness, his truth : this man is greater as 
 well as happier in his poverty, than the other in his riches. The one is 
 but little higher than a beast, the other but little lower than an angel." — 
 Rev. W. Jones of Naylund. 
 
338 
 
 ALG/E FIGUUATiE. 
 
 Fam. XIX. DESMIDEtE. 
 
 Char. Algge rarely filamentous, bipartite, of a figured out- 
 line, highly mucous. 
 
 We have arrived at length at the consideration of a most 
 nteresting group and family of freshwater Alga, the essential 
 characteristics of Avhich are the beautifully figured forms 
 and bipartite composition of the fronds of the numerous 
 sj)ecies of which it is composed. 
 
 The DesmidecB have been the subject of considerable dis- 
 cussion respecting their animal or vegetable nature : the 
 question is now, how^ever, all but settled in favour of their 
 vegetability. Amongst the advocates of their animal nature 
 may be mentioned the names of Ehrenberg and Mr. Dal- 
 rymple : the observations of the latter, however, were con- 
 fined ahnost exclusively to the genus Closterium. 
 
 Ehrenberg rested the claims of the Desmidece to ani- 
 mality upon the mode of their increase by self-division, a 
 method of multiplication which it is now known belongs to 
 all the Algce, and which, therefore, cannot be allowed to have 
 any weight in the decision of the point in question. Mr. Dal- 
 rymple, however, in his memoir on the Closteria *, adduces 
 several otlier reasons for regarding them as animals, two only 
 of which apply at all to the other genera of Desmidea, the 
 remainder being alone applicable to Closterium : ■ — these are, 
 first, the fact that the inner delicate membrane, which lines 
 the outer symmetrical, and usually crescentic covering, con- 
 
 * See "Annals of Xat. Hist." vol. v. p. 415. 
 
DESMIDEiE. 339 
 
 tracts forcibly on the application of certain reagents, the 
 action of which cannot be considered as purely chemical; 
 and second, that iodine docs not detect the presence of starch 
 in the cells. The former observation is equally applicable 
 to the tender membrane which lines the cells of true Con- 
 fervce, while the latter remark is wanting in accuracy, for 
 it is only when the Desmidecs are very young, and before 
 the contents of the cells assume a granular appearance, that 
 iodine does not make manifest the presence of starch ; subse- 
 quently, however, when the endochrome has become granular 
 and vesicular, starch is readily detected by means of iodine, 
 it turning the large vesicular granules of a blue colour. 
 
 Meyen advocated the vegetability of the Desmidca, and 
 was the first to detect the presence of starch in the cells, but 
 the accuracy of his remarks has been doubted ; they are now, 
 however, fully confirmed by Kalfs, Jenner, and the majority 
 of recent algologists. 
 
 The DesmidccB, I conceive then, are to be regarded as 
 vegetable productions, agreeing w^lth the Coiifervce proper, of 
 whose vegetability there can be no question, in the following 
 particulars. 
 
 1st. Probably in the elementaxy composition of the cel- 
 lular tissue. 
 
 2d. In the undoubted presence of starch in the cells. 
 3d. In the multiplication of cells by division. 
 4th. In their reproduction. 
 
 The reproduction of this family has been stated by some 
 writers to be threefold. I am disposed to think, however, 
 that there is but one essential and true mode of reproduc- 
 tion. The tlu'ee methods by which the Desmideoi are stated 
 to be multiplied are, first, by the division of the cells; 
 second, by bodies analogous to zoospores ; and tliird, by 
 true spores, formed as in the Coiijngatece, by the union, 
 intermingling, and condensation of the contents of two 
 distinct individuals. To the family Conjugatcce indeed the 
 Desmidem would appear to be more nearly related than to 
 any other. The first cannot be regarded as a true mode of 
 reproduction; it is but a continual growth, repetition, and 
 ■/. 2 
 
340 DESMIDEiE. 
 
 multiplication of cells; and while it effects the increase of 
 the individuals of a species, does not provide against the ex- 
 tinction of that species when it shall have reached the ter- 
 mination of the brief existence allow^ed to it. Moreover^ the 
 cells resulting from the bisection of other primary cells have 
 no periods of juvenescence and growth ; they are produced 
 at once fully developed and perfect in size and organization. 
 It is the nature, on the contrary, of a true reproduction, that 
 the bodies or organs by which it is effected should be at first 
 minute, and subsequently pass through successive stages of 
 developement. The second method is assuredly the usual and 
 legitimate mode of reproduction, viz. that by bodies analogous 
 to zoospores, while in the third the organs resulting from the 
 union of two individuals are probably to be regarded in the 
 same light in Avhich Agardh viewed the similar bodies of the 
 ConjucjatecB, viz. as receptacles in which the zoospores are 
 stored, and destined, as I think, not for Immediate but for 
 future use, that they are in fact hibernacula, designed to 
 preserve the contained propagules until the vicissitudes and 
 rigour of Avinter shall have passed aAvay. 
 
 The formation of sporangia has been noticed to occur in 
 nearly all the genera of the family of Desmidea, and it is 
 probable that it occasionally occurs in all of them. By 
 Ehrenberg it has been noticed in different species of the 
 genus Closterium, by Brebisson in Desmidium, by Ralfs in 
 his genus Tetmemorus, and in Staurastrum. In the Cylin- 
 drocystis Brehissoni, a production placed by Meneghini 
 amongst the Nostochinece, but which seems to me to belong 
 to Desmidece, union of the cells has been observed, and it is 
 most probable that this union is followed by the formation of 
 sporangia. 
 
 So much for the reproduction of the Dcsmideoi: a few 
 virords.may be added upon their growth. It has already 
 been stated in the definition of the family that certain species 
 of Desmidea are filamentous. The filaments of these in- 
 crease in length though not in number by the continual 
 division of the cells, as do other filamentous Alga; but 
 in tJie Desmidea, which are not formed of filaments, the 
 
DESMIDIUM. 341 
 
 growth of cells is different, and approaches rather more 
 closely to a true i*eproductio]i, which, however, it is not. 
 Each of these Dcsmidia consists of two portions, or cells, fre- 
 quently contracted at their points of junction. These seg- 
 ments, when they have arrived at maturity, separate from 
 each other, and from the open extremity of each a little 
 mucous pouch extends : this imperceptibly increases in size, 
 and finally assumes the form and characters of the originally 
 formed segments. This mode of formation of cells is highly 
 curious, and it is one which may be accounted for by refer- 
 ence to the form and constitution of two portions of those 
 Desmidece which present it. 
 
 Another fact, not as yet alluded to, has been advanced in 
 support of the animality of the Closteria by ]\lr. Dalrymple : 
 this is the presence in each extremity of Clostcrium of a 
 distinct organ or vesicle which contains a number of active 
 and revolving molecules. But moving and revolving par- 
 ticles are met with in many undoubted Algce, and, therefore, 
 their presence in Closterhim cannot be considered as decisive : 
 moreover, no such organ presents itself in any other genus 
 of Desmidece, the proofs of the vegetability of which may 
 be regarded as decisive, and to which the Closteria are too 
 evidently related for the idea to be entertained that the one 
 are animal and the other vegetable productions. 
 
 TJie Dcsmidece are found in old boggy pools, the waters 
 of which are not periodically dried up, but which are i^er- 
 manent for several years. They do not usually float on the 
 surface, but are found in cloud-like masses near the bottom. 
 They are best removed on pieces of linen, on which, if 
 moistened regularly, they may be preserved unaltered for 
 several days. 
 
 Section i. 
 Frond Jilamcnious. 
 
 51. DESIMIDIUM Ag. 
 
 Char. Frond Jilamentous, simple, spiralhj tivisted, fragile, 
 articulated and angular ; mature cells bipartite ; angles 
 /. 3 
 
342 DESMIDEiE. 
 
 mostly bicrenate. Endochrome frequently bipartite, in 
 the transverse view stellate, not filling entirely the cavity 
 of the cells. Reproduction by bodies analogous to zoo- 
 spores. 
 
 Derivation. From Ssa-fio^, a bond. 
 
 a. Filaments with tzco angles. 
 
 * Mucous sheath very evident. 
 
 1. Desmidium cylindricum Grev. 
 Plate LXXXIII. Figs. 1, 2. 
 
 Char. Filaments stout, somexvhat comjoressed, toith two bi- 
 crenate angles. Crenatures strongly marked. Cells 
 rather longer than broad, connected by a thickened border, 
 mucous sheath very evident..- Endochrome ^oz^r or Jive 
 rayed. 
 Grev. Scot. Crypt. Flor. t. 293.; Desmar, n. 1110.; Harv. 
 in Manual, p. 196. Didymoprium Grevillei Kiitzing, 
 PJiyc. Gener. Desmidium cylindricum Ralfs, in An- 
 nals, vol. xi. p. 378. pi. viii. fig. 1. 
 
 Hab. Scotland : Dr. Greville. At the bottom of shallow 
 pools and ditches, Appin : Captain Carmichael. In old 
 peat pits about Dolgelly, North Wales ; sparingly near 
 Penzance : JSIr. Ralfs. In a watercourse on Chiltington 
 Common, near Pulborough, Sussex : Mr. Jenner. Ches- 
 hunt : A. H. H. In Caragli Lake, Kerry : Mr. An- 
 drews. Bog holes, CO. INIeath : Mr. 3Ioore. 
 
 The above description embraces all the essential characters 
 of the species which may be regarded as the type of the 
 genus. In consequence of the spiral twisting of the filaments 
 the crenatures arc much more perceptible in certain cells than 
 in others ; they are most strongly marked as a rule at about 
 every tenth cell, gradually diminishing from these towards 
 the central cells of the series, where they are much less ap- 
 parent, and where the extremities of the crenatures, instead 
 
DESMIDIUM. 343 
 
 of being pointed are truncate. This species, as well as in- 
 deed all the Desmidece, are most beautiful microscopic objects. 
 I do not see the necessity for instituting a new genus for its 
 reception. I have not, therefore, adopted that of Kiitzing ; 
 viz. Didymoprium. 
 
 ** Mucous sheath 7iot ajiparent. 
 
 2. Desmidium Borreri Ralfs. 
 
 Plate LXXXIII. Figs. 9, 10. 
 
 Char. Filaments slender. Cells hiangular, viflatcd, elongated, 
 being about tivice as long as broad. Eudochrome^ue or 
 six rayed. 
 
 Desmidium Borreri Kalfs, in Annals of Nat. Hist., vol. xi. 
 J). 375. t. 8. p. 4. Didymoprium Borreri Jenner, in 
 Fl. Tunbridge Wells, p. 192. 
 
 Hab. Boggy ditch at Crom Bychan : Mr. Borrer. Llyn 
 y Cwyn ; Mr. Borrer and Mr. Ralfs. In all peat bogs 
 near the outlet of Llanberris Lakes and near Dolgelly, 
 North Wales : I\Ir. Ralfs. On Ashdown Forest near 
 Buddies Well ; in the great bog near Forest Row, and 
 at Chiltington Common, near Pulborough : 3Ir. Jenner. 
 Bog holes, CO. jMeath : Blr. Moore. 
 
 This is one of the most graceful and easily recognised spe- 
 cies of the genus, remarkable principally for the great length 
 of the cells ; the endochrome in each cell is distinctly divided 
 into two masses, which arrangement imparts to the plant 
 somewhat the appearance of a Tyndaridea. 
 
 The cells are somewhat inflated, and each resembles in 
 form two flower-pots juxtaposed by their mouths ; the rims 
 being represented by the crenaturcs of the cells, between 
 which passes circularly round each cell a superficial groove, 
 in the situation of which the cells at an advanced period of 
 their developement separate, and give issue to their granular 
 contents. Viewed transversely, the cells are spherical, with 
 shght lateral projections. 
 
344 DESMIDE^. 
 
 b. Filaments triangular. 
 
 * Mucous sheath 7iot aj)parent. 
 
 3. Desmidium Swartzii Ag. 
 
 Plate LXXXIII. Figs. 7, 8. 
 
 Char, Filaments triangular. Cells rather shorter than broad, 
 bicrcnate, angles of the cells icell marked. Endochrome 
 three-rayed. 
 
 Grev. Scot. Flor. t. 292. ; Eliren. Die Infus. p. 140. t. 10. 
 f. 8. ; Pritch. Infus. p. 183. ; Harv. in Manual, p. 196. ; 
 Ag. Syst. p. 9. ; Ralfs, in Annals of Nat. Hist. vol. xi. 
 p. 375. plate viii. fig. 3. ; Jenner, in loc. cit. p. 192. 
 
 Hab. Scotland : Dr. Greville. Appin : Captain Car- 
 michael. Tunbridge Wells : Mr. Borrer. Swansea, 
 South Wales ; Caernarvon and Dolgelly, North Wales ; 
 Penzance : Mr. Ralfs. High Beech, Epping : A. II. H. 
 Rusthall Common, and in a pond between Eamslye 
 rocks and Broad water Forest ; Battle; Chiltington Com- 
 mon, near Pulborough : Mr. Jenner. Bog holes, co. 
 Meath: 3Ir. Moore. 
 
 In consequence of the filaments of this species being trian- 
 gular, the spiral twisting of the threads is more evident than 
 in any otiier species of the genus. When the microscope 
 is brought to bear upon any filament, two of the three lines 
 of crenatures are visible, and the third is indicated by a dark 
 waved line passing from one margin of the filament gradually 
 towards the other, the dark appearance of the line being- 
 occasioned by the dense endochrome of the cells situated 
 immediately behind the crenatures. 
 
 Kiitzlng limits the genus Desmidium to this one species, 
 which he considers to differ generically from the other species 
 usually associated with that genus, in the fact of the presence 
 of the third angle to the cells — a distinction not considered to 
 to be sufficient in the case of the genus Staw^asfrian for 
 the foundation of new genera. The German professor has 
 
DESMIDIUM. 345 
 
 therefore been induced to institute a new genus for D. 
 cylindricum, under the name oi Didymoprium. This genus, 
 in my humble opinion, ought not to be adopted ; and if it be 
 really a good and valid genus, then is there sufficient reason 
 why D. Borreri should form the type of a genus different 
 from both, for it differs from D. Sioartzii in the cells being 
 biangular and not triangular, and from Desmidiuvi cylindricum 
 Grev., the Didymopriiim Grevillci of Kiitzing, in the absence 
 of a mucous sheath. There would thus be as many genera as 
 there were formerly considered to be species of Dcsmidia, a 
 result not altogether satisfactory. 
 
 c. Filaments loitlifour angles. 
 
 4. Desmidium quadrangulatum Balfs. 
 
 Plate LXXXIV. Fig. 3. 
 
 Char. Filaments quadrangular. Endochrome/b2/?--r«ya?. 
 Ralfs, In Annals, vol. xv. p. 405. pi. xii. fig. 9. 
 Hah. In a boggy pool at Balogas, near Penzance : Mr. 
 Ralfs. 
 
 Notwithstanding the strong resemblance which it bears to 
 Desmidium Sivartzii, this plant appears to me to be very dis- 
 tinct. In consequence of the filaments having four angles 
 instead of three, and as they are spirally twisted in the 
 same manner as those of other Dcsmidia, it follows, that two 
 dark, and waved lines, describing two of the four angles, are 
 visible in the length of tlie thread. The observation of these 
 will at once serve to distinguish it from Desmidium Swartzii, 
 of which ]Mr. Berkeley, Mr. Borrer, and Mr. Ralfs consider 
 this plant to be a variety : the latter, however, remarks 
 that he has gathered it for two successive years quite unmixed 
 wath that species. 
 
 It seems to me that this plant has not merely a right to be 
 considered as specifically distinct from D. Swartzii, but nearly 
 as much claim (a claim however Mhicli I do not allow) to be 
 
346 DESMIDE^. 
 
 regarded as generally distinct therefrom, as D. cylindricum 
 and D. Swarf zii have to be so considered.* 
 
 52. GL^OPRIUM Berh MSS. 
 
 Char. Filaments cylindrical, invested in a broad elastic sheath. 
 Cells slightly crenate. Endochrome stellate. 
 
 From the above definition it would appear that this genus 
 does not differ in any marked manner from Desmidiiim 
 There is certainly more ground for its formation than for the 
 establishment of Kiitzing's Didymoprium ; but perhaps the 
 ends of science and of nomenclature would have been an- 
 swered to have placed the two species which it is made to 
 comprise and which differ as Avidely from each other as they 
 do almost from the genus Desmidiwn in a distinct section of 
 that genus. 
 
 1. Gl^OPKIUM dissiliens Berk. 
 Plate LXXXIII. Figs. 3, 4. 
 
 Cfiar. Filaments fragile. Cells slightly crenate, grooved be- 
 tween the crenatures, nearly as long as broad. Sheath 
 broad. Endochrome six or seven rayed. 
 Desmidium mucosum Breb. Conf. dissiliens, Eng. Bot. 
 t. 2464. D. inucosum Ealfs, in Annals, vol. xi. p. 374. 
 plate viii. fig. 2. Glaoprium dissiliens Jenner, in Fl. 
 Tunbridge Wells, p. 192. 
 Hah. Crom Byclan : W. Borrer, Esq. Tunbridge Wells 
 and other places in Sussex, frequent : Mr. Jenner. Near 
 Bedgelert and about Dolgelly, North Wales ; Swansea, 
 South Wales ; plentiful near Penzance, Cornwall : Mr. 
 Ralfs. High Beech, Essex; Hertford Heath and 
 
 * ISIr. Jenuer has pointed out a character wbicli seems to set the ques- 
 tion of the distinctness of this species at rest. He states that in Desmidium 
 quadrangulatum the angles of the cells are rounded, while in D. Swartzii 
 they are acute. 
 
GL^OPRIUM. 347 
 
 Wormley West End, Herts : A. 11. H. Bandon : Prof. 
 G. J. Allman. Co. Kerry : Mr. Andreics. 
 
 The filaments wlien viewed separately, or as regards the 
 line of cells are rather slender, but when taken in connec- 
 tion with the broad sheaths, their diameter is considerable; 
 this sheath, though expanded and firm, often, unless a good 
 microscope be used, escapes detection. It is from the pre- 
 sence of this sheath that the plant owes its excessive muco- 
 sity, and it is by it that we account for the parallel arrange- 
 ment which the filaments frequently assume on the field of 
 the microscope, without at the same time appearing to touch 
 each other, although they really do so by means of the almost 
 invisible mucous sheath. The contrast between the coloured 
 cells and the transparent sheath renders this an exceedingly 
 beautiful microscopic object. 
 
 2. Gl^oprium mucosum Berk. 
 
 Plate LXXXIII. Figs. 5, 6. 
 
 Char. Filaments not fragile. Cells usually nearly as long 
 as broad, not grooved round the centre. Angles of cells 
 mostly minutely bicrenate. Sheath very broad, faint. 
 
 Conf. mucosa Mertens, Dillw. Syn. t. /9; Harvey, in 
 
 Hook. Br. FI. p. 351. ; also in Manual, p. 127. Glao- 
 
 prium mucosum Jenner, in Flora of Tunbridge "Wells. 
 
 Desmidium bimucronatum Hassall, j\ISS. 
 
 Hob. In stagnant water, Bautry : Miss Ilutchins. Appin : 
 
 Captain Carmichael. Cheshunt Common, High Beech 
 
 and elsewhere : A. H. H. Penzance : Mr. Ralfs. Bogs 
 
 at Fisher's Castle, very abundant, Sept. 1844; Chilting- 
 
 ton Common : Mr. Jenner. 
 
 Tliis species differs very considerably from the previous one, 
 
 in having somewhat longer cells, a more higlily developed 
 
 mucous sheath, in the absence of the central constriclion of 
 
 the cells, and in the presence of the excessively minute bicrenate 
 
 processes placed at the angles of the cells, and which were 
 
348 DESMIDE^. 
 
 noticed by Mr. Ralfs and Mr. Jenner nearly simultaneously. 
 The processes are not present at all the angles of every cell, 
 but only at those angles which have been for the longest 
 period formed : thus, when a cell has become but recently 
 divided no processes are present on the newly formed angles 
 which result from this division. Owing to the existence of 
 the highly developed mucous sheath, the filaments are dis- 
 posed often as in the previously described species parallelly. 
 
 Mucous sheath much broader than in G. dissiliens, but less 
 perceptible. 
 
 53. SPHiEROZOSMA Corda, 
 
 Char. Filaments very fragile, compressed, consisting of bipar~ 
 tite cells imited by means of gland-like processes, and much 
 constricted between each cell. 
 
 This genus Is distinguished from the previous genera by 
 its compressed frond, and by the glandular processes at the 
 junction of the cells. 
 
 1. Sph^rozosma elegans Corda. 
 Plate LXXXIV. Fig. 1. 
 
 Char. Cells smooth, rather longer than broad, deeply divided 
 on each side into two portions. Glands single, one in the 
 centre of each margin. 
 Sphcerozosma elegans Corda, Almanac de Carlsbad, 1835, 
 t. iv. f. 37. Odontella ? unidentata Wax., Infus. p. 159. 
 Desmidium compressum, Annals of Nat. Hist. vol. ix. 
 p. 253. Schistochilum Ralfs, unidentatum Jenner, in Fl. 
 of Tunbridge Wells, p. 192. Desmidium vertebratum 
 Brcb. et Godey. 
 Hab. Chyan-hal Moor, near Penzance ; and ToAvednack 
 Moor, near St. Ives : Mr. Ralfs. Rotherfield, and in 
 Jack's Wood spring : Mr. Jenner. 
 For tlic figures of this and the following species I am in- 
 debted tQ Mr. Jenner. 
 
GONIOCYSTIS. 349 
 
 2. SPHiEROZOSMA EXCAVATUM. 
 
 Plate LXXXIV. Fig. 2. 
 
 Char. Cells longer than broad, excavated laterally, icith ttvo 
 (jlands or teeth at each margin. 
 Schistochilum excavation Ralfs, IMS. ; Jenncr, In Flora of 
 Tunbridgc Wells, p. 192. 
 
 Ilab. In a boggy spot near Cross in Hand, opposite to 
 where the road branches to Hailsham ; bogs at Fisher's 
 Castle, and in a pond between Ranislyc and Broadwater 
 Forest : Mr. Jenner. 
 
 A very distinct and interesting species. 
 
 Section il. 
 Frond not forming filaments. 
 
 54. GONIOCYSTIS Ilass. 
 Char. Cells angular. 
 
 Derivation. From jcovta, an angle, and Kvcrri9, a cell. 
 
 Section i. Trigonocystis Ilass. 
 
 Char. Cells with three angles. 
 
 Derivation. From TpLywvov, triangular, and kvctls, a cell. 
 
 1. Trigonocystis orbicularis Ilass. 
 
 Plate LXXXIV. Fig. 7. 
 
 Char. Frond smooth, suhorhicular. End view triangular. 
 Angles obtuse. 
 Staurastrum orbiculare INIeneghini, Synop. Dcsmid. p. 225. 
 Desmidiiim orbiculare Ehr., Infus. p. 141. tab. 10. fig. 9. 
 Staurastrum orbiculare Ralfs, in Annals, vol. xv. p. 152. 
 pi. X. fig. 4. a. b. c. ; Jenner, in loc. cit. p. 192. 
 
350 DESMIDE^. 
 
 Hah. Jack's Wood spring ; Cross in Hand, &c. : Mr. 
 Jenner. Dolgelly and Penzance : Mr. Ralfs. 
 
 The fronds are rather large, smooth, deeply constricted in 
 the centre ; the segments, broader than long, are in close ap- 
 proximation with each other, and when taken together form 
 an orbicular frond in their front view, in which aspect the 
 species might be taken for a Cosmariiim, from which genus 
 it differs in the triangular transverse form of the segments. 
 
 T. orbicularis forms a distinct Knk betAveen Cosmarium on 
 the one side and Desmidium on the other. It is distinguished 
 from the following species by its suborbicular frond and by 
 its blunt angles being destitute of processes. 
 
 2. Tpjgonocystis mucronata Hass. 
 
 Plate LXXXIV. Fig. 8. 
 
 Char. Fronds smooth, deeply constricted in the front vietv, seg- 
 ments cither transversely elliptical or lunate. End view 
 three-lobed. Lobes inflated, blunt, mucronate, a single 
 mucro terminating each lobe. 
 a In the front view the segments are transversely elliptic 
 
 and the mucro straight. 
 /3 Segments, in front view, transversely lunate, outer mar- 
 gin straight, mucro curved outwards. 
 7 Segments, in front view, transversely lunate, outer margin 
 curved, mucro curved inwards. 
 
 Staurastrum mucronatum Kalfs, in Annals, vol. xv. p. 152. 
 pi. X. figs. 5, 6.; Jenner, in loc. cit. p. 192. 
 
 Hab. On Ashdown Forest ; Piltdown Common ; Fisher's 
 Castle, and near Cross in Hand : Mr. Jenner. Dol- 
 gelly and Penzance : Mr. Ralfs. 
 
 This, although a variable species, would appear to be Avell 
 characterised by the lobed form of the segments viewed end- 
 ways and the presence of the spine-like teeth. 
 
 Mr. Ralfs and Mr. Jenner have observed the occurrence 
 
GONIOCTSTIS. 351 
 
 and formation of sporangia in this species, resulting as in other 
 DesmidccB from the union of the cndoclu'omes of two cells, 
 which in them is never effused from one cell into another, 
 but always into a distinct receptacle intermediate between 
 the two fronds: this is also the case in certain species of 
 Tyndarideoi and Mesocarpi amongst the Conjugates. 
 
 The sporangia in T. mucronata are circular and smooth, 
 and at first enclosed in a membrane larger than itself, this 
 gradually disappears, and the sporangium becomes spinous, 
 in which state it bears some resemblance to a Xanthidium. 
 I have observed occasionally the sporangia of the Vesicu- 
 lifer<2 to present an appearance exactly similar, a fact wliich 
 has not escaped the attention of Mr. Thwaites. 
 
 3. Trigonocystis muricata Hass. 
 
 Plate LXXXIV. Fig. 9, 10. 
 
 Char. Fronds muricated, deejjly constricted, transversely el- 
 liptic. Segments approximate. End view triangnlar, iciih 
 convex sides. 
 
 /3 Yvonds fur 7iished with short spines. 
 
 Meneghini, Synops. Desmid. p. 266. Binatclla muricata 
 Breb., Alg. Fal. p. QiQ. (1835). Desmidium apiculosum 
 Ehr., Infus. p. 142. ; Ralfs, in Annals, vol. xv. p. 154. 
 pi. xi. fig. 1.; Jenner, in loc. cit. p. 194. — /3. Xanthi- 
 dium deltoidcum Corda, Observ. INIicroscop. sur les iVui- 
 malc. de Carlsbad, p. 29. pi. v. figs. 38, 39. 
 
 Hab. In small pools ; Cheshunt : A. H. H. "Weston Bogs, 
 Hants ; Rackham Common, near Pulborough ; Pilt- 
 down Common, near Uckfield ; Mayfield and Heathficld. 
 Sussex : Mr. Jenner. Dolgelly and Penzance : Mr. 
 Ralfs. — /S. Sussex: Mr. Jenner. Dolgelly: Mi-. Ralfs. 
 
 From Sfaurastr7nn tricorne this species may be at once dis- 
 tinguished by the convex sides of the segments in the end 
 view, and by the adult fronds being not merely muricated 
 but spinous. The variety is probably distinct. 
 
352 DESMIDE^. 
 
 4. Trigonocystis hexaceros Hass. 
 Plate LXXXIV. Fig. 11. 
 
 Char. Fronds rough. Segments ahovt twice as long as 
 broad, separated from each other by a deep notch, ttvisted. 
 End view triangular, icith concave sides and blunt entire 
 angles. 
 S. tricorne Meneghini, Synopsis Desmid, p. 225. Binatella 
 tricoryiis Breb., Alg. Fal. p. 57. (1835). Desmidium 
 hexaceros Ehr., Abhand. der Akademie d. Wisseusch. 
 zu Berlin (1832), p. 292. ; Ehr. Die Infus. p. 141. t. x. 
 fig. 10. Staurastrum tricorne Ealfs, in Annals, vol. v. 
 p. 155. pi. xi. fig. 2. ; Jenner, in loc. cit. p. 194. 
 Hab. Shallow pools, Piltdown Common; Ashdown Forest; 
 Rusthall Common ; between May field and Hadlow 
 Down: Mr. Jenner. Barmouth: Rev. T. Salivey. Dol- 
 gelly and Penzance : BIr. Ralfs. High Beech : A. H. H. 
 " The conic granules arranged in transverse lines at the 
 angles are generally very minute, but in some Sussex spe- 
 cimens gathered by INIr. Jenner they are large, and on the 
 margin produce a dentate appearance." — Ralfs. 
 
 5. Trigonocystis gracilis Hass. 
 Plate LXXXV. Fig. 1. 
 
 Char. Fronds muricated, deeply constricted in the centre, ttvo 
 or three times longer than broad, tapering on each side into 
 a slender process, ichich is terminated by three minute teeth. 
 End view triradiate. 
 Euastrum No. 13. ^ailey, in American Bacillaria, pi. i. 
 fig. 2 — 5. Staurastrum gracile Ralfs, in Annals, vol. 
 XV. pi. xi. fig. 3. 
 Hab. Boggy pools, Dolgelly, and Penzance : Mr. Ralfs. 
 Althougli but three processes or teeth usually present them- 
 selves to the observer, the real number is four ; but this is only 
 to be seen when one of the angles or rays is so situated that 
 its extremity is directly presented to the observer. 
 
GONIOCYSTIS. 353 
 
 6. Trigonocystis ? aculeata Hass. 
 Plate LXXXIV. Fig. 12. 
 
 Char. Fronds spinous. Segments in the front view, ^cith a 
 process on each side terminating in three minute spines. 
 End view triangular, with concave sides. 
 
 yS End view quadrangular, with four distorted rays. 
 
 Staurastrum aculeatum INIencgli., Synops. Desmid. p. 226.- 
 Dcsmidium aculeatum Ehr., Infiis. p. 142. t. 10. fig. 12. ; 
 Ralfs, in Annals, vol. xv. pi. xi. fig. 4. ; Jenner, in loc. 
 clt. p. 194. 
 
 Hah. Cross in Hand; Sussex, and Becklcy Furnace: 
 Mr. Jenner. Penzance: Mr. Ralfs. —/3. Woking Com- 
 mon, Surrey, and Piltdown Common, Sussex: 3Ir. 
 Jenner. Penzance: 31?'. Ralfs. 
 
 The spines are larger and longer in this than in any other 
 species of the genus. The variety, which I have not seen, 
 would appear to be referrible to the species proper, and is 
 therefore very interesting.* 
 
 Section ii. Stjurastrvm Ehr. 
 
 Char. End view quadrangular, often four-rayed, rays of one 
 segment diverging from those of the other. 
 Derivation. From aravpos, a cross, and aarpov, a star. 
 
 1. Staurastrum dilatatum Ehr. 
 
 Plate LXXXV. Fig. 5. 
 
 Char. Frond rough, deeply constricted in the centre. Seg- 
 ments twice as broad as long, obtuse at the sides, and not 
 elongated into processes. End view quadrangidar. An- 
 gles obtuse, sides excavated. 
 Ehr. Die Infus. p. 143. t. 10. fig. 13.; Menegh. Synops. 
 
 * Is not the normal niunber of rays in this species four, and is it not 
 therefore a Staurudnim ? 
 
 A A 
 
354 DESMIDE^. 
 
 Desmid. p. 227. ; Ralfs, in Annals, vol. xv. pi. xi. 
 fig. 5.; Jenner, in loc. cit. p. 194. 
 Hah. Eusthall Common, near Tunbridge Wells; and 
 Eackham Common, near Pulborougli, Sussex: 3Ir. 
 Jenner. Dolgelly : Mr. Rolfs. 
 
 The angles in this species are not as in the others prolonged 
 into rays, and this will at once serve to distinguish it from 
 those species. 
 
 2. StAURASTRUM ? TETRACERUM Ralfs. 
 
 Plate LXXXIV. Fig. 4. 
 
 Char. Frond rough. Segments hut slightly constricted, qua- 
 driform. Outer angles prolonged into diverging rays 
 lohich are eiitire at their extremities. End view com- 
 jjressed, toith a j)rocess at each extremity. 
 Staurastrum paradoxum Ehr., Infus. p. 143. t. 10. fig. 14. 
 Micrasterias tricera and tetracera Kiitz., Synops. Desmid. 
 in Linuaja, 1833, p. 602. figs. S3, 84, S5.; Ealfs, in 
 Annals, vol. xv. pi. x. fig. 1. 
 Hob. Dolgelly and Penzance : Mr. Ralfs. 
 
 The minute granules with which the frond is covered form 
 transverse lines on the rays, and give them a jointed appear- 
 ance. This species, in its compressed ellipsoidal form in the 
 end view, would appear to approach closely the genus Ar~ 
 throdesmus. 
 
 3. Staurastrum paradoxum Meyen. 
 Plate LXXXV. Fig. 3. 
 
 Char, Fronds rough, constricted. Ends truncate. Front view 
 elongated, diverging processes minutely trijid. End vievf 
 usually quadrangular, hut sometimes triangular. 
 Meyen, Nov. Act. Scap. Holm. vol. xiv. p. 43. figs. 37. 38.; 
 Menegh. Synops. Desmid. p. 227. Micrasterias Staur- 
 astrum Kiitz., in Linnrea, p. 399. ; Kalfs, in Annals 
 vol. XV. p. 151. pi. X. fig. 2. 
 
GONIOCYSTIS. 355 
 
 Hab. Dolgelly aud Penzance : Mr. Ralfs. 
 This Staurastrum is to be distinguished from the previous 
 species by the trifid extremities of the rays. 
 
 4. Staurastrum ? bifidum Ralfs. 
 Plate LXXXV. Fig. 2. 
 
 Chai: Frond smooth^ hut little constincted in the centre, truncate 
 laterally. Rays trijid. End view triradiate. 
 Desmidium bijidum Ehr., Die Infus. p. 141. t. 10. f. 11. ; 
 
 Ealfs, I.e. p. 151. pi. X. fig.3. 
 Hab. Dolgelly and Penzance : Mr. Ralfs. 
 
 The smoothness of the frond will always distinguish this 
 from the previous species. It should probably be referred to 
 Trifjonocystis. 
 
 Section iii. Pentasterias Ehr. 
 
 Char. Frond in front view without diverging processes. End 
 view circular, with usually five rays. 
 Derivation. From TrsvTs^five, and aarepia?, starred. 
 
 1. Pentasterias arachnis Ilass. 
 Plate LXXXV. Fig. 8. 
 
 Char. Frond rough, deeply constricted in the centre. Seg- 
 ments about as long as broad, sid) orbicular, with elongated 
 slender hyaline and incurved processes. End view Jtvc- 
 rayed. ■ 
 Staurastrum Arachne Ealfs, in Annals, vol. xv. p. 157. 
 
 pi. xi. fig. 6. 
 Hab. Boggy pool near Dolgelly, \cvy rare : Mr. Ralfs. 
 
 " This plant is remarkable for its slender processes which 
 will easily distinguish it from St. mnrgaritaceum. It cannot 
 be a five-rayed variety of St. gracile, for the rays arc longer, 
 more slender, remarkably incurved, and also entire at the 
 extremity." — Ralfs. 
 
 s. K 2 
 
356 DESMIDE.E. 
 
 2. Pentasteeias maegaritacea Ehr. 
 
 Plate LXXXV. Fig 7. 
 
 Char. Frond rough. Segments in front view siibglohose, at- 
 tenuated at their junction, with short lateral converging 
 l^rocesses which are entire at their ajjices. End view ivith 
 Jive, rarely six or seve?i, short obtuse rags. 
 
 Staurastrum margaritaceum Menegli., Synops. Desmid. 
 
 p. 227. ; Ralfs, in Annals, vol. xv. p. 157. pi. xi. fig. 7. 
 
 Pentasterias margaritacea Ehr., Infus. p. 144. t. 10. 
 
 fig. 15. ; Jenner, in loc. cit. p. 194. 
 Hah. Dolgellj : Mr. Ralfs. Ashdown Forest, Sussex : 
 
 Mr. Jenner. 
 
 The rays are much stouter and shorter in this than in the 
 preceding species. 
 
 3. Pentasterias Jenneri Hass. 
 
 Plate LXXXV. Fig. 6. 
 
 Char. Fronds large, dentated. Segments about as broad as 
 long, lengthened into a toothed angle on each side. End 
 view with five, sometimes six, broad short-toothed rays. 
 
 Staurastrum Jenneri Palfs, in Annals, vol. xv. p. 158. 
 pi. xi. fig. 8. ; Jenner, in loc. cit. 
 
 Hab. Mayfield, Sussex : Mr^ Jenner. 
 
 A very fine species. " The transverse view has a large 
 central opening surrounded by a row of large granules." — 
 Ralfs. 
 
 55. ARTHRODESMUS Ehr. 
 
 Char. Fronds smooth, deeply constricted. End view com- 
 jjressed, angles prolonged into a spine. 
 
 Derivation. From apOpov, a joint, and heajjios, a link. 
 
 The stout spines terminating the angles of the segments 
 seem to connect this genus with Xanthidium. 
 
ARTHRODESMUS. 357 
 
 1. Artiirodesmus convergens Ehr. 
 
 Plate LXXXV. Fig. 9. 
 
 Cha7\ Segments broader than lonrj, somewhat elliptic, elon- 
 gated at each side into an incurved spine. End view 
 compressed, with a spine at each extremity. 
 
 Artiirodesmus convergcns Ehr., Iiifus. p. 152. t. 10. fig. 18. 
 Staurastrum convergcns INIenegli., Synops. Desmid. 
 p. 228. ; Ralfs, in Annals, vol. xv. p. 158. pi. xii. fig. 1. ; 
 Bailey, Amer. Bacil. pi. i. fig. 11. ; Jenner, in loc. cit. 
 p. 194. 
 
 Hah. Brarabletye, near East Grinstcad ; Rackliam Com- 
 mon, near Pulborough, Sussex ; and Rustliall Common, 
 near Tunbridge Wells : Mr. Jenner. Dolgelly and 
 Penzance : 71/?-. Balfs. Cliesliunt : A. H. H. 
 
 The incurA^ed mucroncs will at once serve to distinguish 
 this species. 
 
 2. Arthrodesmus Incus Hass. 
 Plate LXXXV. Fig. 10. 
 
 Char. Segments externally lunate, xcith a mucro at each 
 angle. End A'iew elliptic, mucronatcd at each extremity. 
 Euastrum Bailey, Amer. Bacil. pi. i. fig. 12. ? Staurastrum 
 Incus Meneghini, Synops. Desmid. p. 228. ; Balfs, in 
 Annals, vol. xv. p. 159. pi. xii. fig. 2. ; Jenner, p. 194. 
 
 Hah. Weston Bogs, near Southampton ; Rackham Com- 
 mon, near Pulborough, Sussex : Mr. Jenner. Dolgelly 
 and Penzance : Mr. Balfs. 
 
 The mucro in tins species is turned outwards : in the front 
 view the segments resemble those of Trigoyiocystis mucrO' 
 nata, but the end view is very diftcrent. 
 
 3. Artiirodes.aius octocornis Ehr. 
 
 Plate LXXXV. Fig. 11. 
 
 Cliar. Fronds compressed. Segments broader than long, 
 A A V, 
 
358 DESMIDE^. 
 
 quadrangular, each angle produced into a spine. End 
 view subelliptic, with a spine at each extremity. 
 
 Arthrodesmus octocornis Ehr., lufus. p. 152. S.f octocorne 
 
 Kalfs, in Annals, vol. xv. p. 159. pi. xii. fig. 3, 
 Hab. Boggy ponds near Dolgelly, rare : Mr. Ralfs, 
 
 " The newly formed segments at first have only two 
 spines, and in this state somewhat resemble those of Staur- 
 astrum Incus, of which indeed this plant may eventually 
 prove a variety. But S. Incus has only two spines on each 
 segment, and its end is not concave but truncate." — Ralfs. 
 
 The Micrasterias octocornis of Meneghini would appear to 
 be a different plant. 
 
 56. XANTHIDIUM Ehr. 
 
 Cfiar. Frond composed of two slightly compressed segments 
 constricted in the centre, neither lobed, sinuated, nor emar- 
 ginate. Surface clothed with simyle or branched elon- 
 gated spines, either scattered or confined to the margin, 
 where they are apparently placed in two roxos, one on each 
 side the marginal lines. Segments anteriorly perforated 
 in the centre (?). 
 Derivation. From ^avOos, yelloiv ? 
 
 This genus bears a close resemblance to Cosmarium, from 
 which there is no satisfactory character to distinguish it, 
 unless indeed the projection or aperture noticed to occur by 
 Mr. Dalrymple in Xanthidium furcatum, and by INIr. Ralfs 
 In X. aculeatum be constant in all the true species of the 
 genus Xanthidiuyn. Meneghini even goes so far in the union 
 of the genera Xanthidium and Cosmarium, as to retain in the 
 former genus only those species whose spines are scattered 
 over the surface, while he refers to the latter genus those in 
 which the spines are confined to the margin. This arrange- 
 ment seems arbitrary ; and that it is so, is j^roved by the fact 
 that in a species of Xanthidium figured by Dr. Bailey in the 
 " American Bacillaria," and which has six pairs of marginal 
 
XANTHIDIUM. 359 
 
 spines, the central apertures exist ; that is, in the species re- 
 ferred by Meneghini to Cosmarium these openings are met 
 with — the only character which is even supposed to belong 
 exclusively to Xanthidium. 
 
 " I have little doubt that there arc more British species of 
 Xanthidium than I shall here describe, and indeed believe 
 that I have more than once gathered X. Idrsutiim ; but as 
 my attention was not directed to the Desmidcca at the time, 
 I neglected to examine it with sufficient care to be able to 
 state my observations with any confidence in this paper." — 
 Ralfs. 
 
 1. Xanthidium furcatum Ehr. 
 Plate LXXXIX. Fig. 1. 
 
 Char. Segments reniform. Spines at first marginal, sub- 
 seqiiently scattered, dividing at their terminations into 
 three or four acute divergent points. 
 Xanthidium furcatum Ehr., Infus. p. 148. tab. x. f. xxv. ; 
 Menegh. Synops. Desmid. p. 224. Xanthidium No. 2., 
 Bailey's American Bacillaria, p. 291. pi. i. fig. 15. ; 
 Ealfs, inAunals, vol. xiv. p. 466. pi. xii. fig. 1. 
 Hah. Several j^laces in Sussex : Mr. Jenner. Dolgclly, 
 and near Carmarthen : ilfr. Ralfs. High Beech and 
 Cheshunt Common : A. H. H. Aberdeen : Dr. Dickie. 
 L-eland : Mr. Moore. 
 
 This is the finest as well as commonest species of the genus. 
 There is no other Avith which it can be confounded. 
 
 In the figure of this species, given by Ehrenbcrg, the een- 
 tral aperture seems to be indicated. 
 
 2. Xanthidium fasciculatum Ehr. 
 Plate LXXXIX. Fig. 2. 
 
 Char. Segments small, reniform. Spines in pairs, and 
 usually six pairs to each segment. 
 Xanthidium aculeatum, Abhandl. d. Akademie d. ^Visscnsch. 
 
S60 DESMIDE^. 
 
 zu Berlin, 1833, p. 318. X. fasciculatum Ehr., Infus. 
 p. 147. tab. X. fig. xxiv. b. Xantkidium fasciculatum 
 Ralfs, in Annals, vol. xiv. p. 166. fig. 3. c. d. e. Cos- 
 marium aculeatum Menegh., 1. c. p. 218. Euastrum 
 No. 10., Bailey's Amer. Bacil. p. 296. pi. i. fig. 10. ; 
 Jenner, in loc. cit. p. 194. 
 
 This species is smaller than the following, the segments of 
 a different form, and the spines more numerous. 
 
 3. Xanthidium polygonum Hass. 
 
 Plate LXXXIX. Fig. 4. 
 
 Char. Frond polygonal. Segments four-angled. Spines 
 eight to each segment, in pairs, situated at the angles. 
 Xanthidium fasciculatum ^polygonum Ehr., Infus. p. 148. 
 t. 10. fig. 24. a. Xanthidium fasciculatum /S poly- 
 gonum Balfs, in Annals, vol. xiv. p. 467. pi. xii. 
 fig. 3. a. b. 
 Hah. Near Dolgelly : Mr. Ralfs. Near Tunbridge Wells : 
 Mr. Jenner. 
 
 This doubtless ought not to be regarded as a variety, but 
 as a distinct species, differing from Xanthidium fasciculatum, 
 of which it has hitherto been regarded as a variety, in being 
 altogether a much larger plant, in the polygonal form of the 
 segments, and in the number of the spines to each segment, 
 which are eight in X. polygonum, arranged in four pairs, wliile 
 in X. fasciculatum they are twelve, disposed in six pairs. 
 
 4. Xanthidium aculeatum Ehr. 
 
 Plate LXXXIX. Fig. 3. 
 
 Char. Segments reniform, almost globose. Spines sijigle, 
 marginal, and scattered. 
 Xanthidium ««<Zm^M??i Ehr., Infus. p. 147. tab. 10. fig. 23.; 
 Menegh. 1. c. p. 224.; Ralfs, in Annals, vol. xiv. p. 467. 
 pi. xii. fig. 2. a. b. c. d. 
 
COSMARIUM. 361 
 
 Hab. Aslulown Forest, and near Cross in Hand : Mr. 
 Jenner. Penzance : Mr. Ralfs. 
 
 Tills species differs from X. fascicuJatum principally in the 
 spines being single and not in pairs as in that species. 
 
 " In the centre of each segment, on both surfaces, is a pro- 
 jection similar to that described under X. furcatum, but less 
 evidently dentated." — Ralfs. 
 
 57. CYLINDROCYSTIS Menegh. 
 
 Char. Frond mucous, indefinite. Corpuscles cylindrical, filled 
 ivitk sporidia, copulating, at length hearing two spores 
 transversely divided into halves. 
 Derivation. From Kv\iv8po9, a cylinder, and Kvcrris, a cell. 
 
 1. Cylindeocystis Brebissoni Menegh. 
 
 Plate XCII. Fig. 17. 
 
 Char. Cells cylindrical, two or three times longer than broad, 
 with rounded extremities. 
 
 C. Brebissoni Menegh., Monog. Nostoc. Italic. 
 
 Hab. Sussex : Mr. Jenner. High Beech : A. II. II. 
 Aberdeen: Dr. Dickie. Galway : BPColla. 
 
 This is a particularly interesting production, as It seems to 
 form a direct link bet\\"een the ProtococcoidecB and the Des- 
 midece, and by ISIeneghini himself is placed in the family 
 NostochinecB. The conjunction of the cells, as well as their 
 great size and regular form, have Induced me to refer it to the 
 Desmidece, in which the phenomenon of union of the cells is 
 of such frequent occurrence. The frond does not appear to 
 be divided in the centre as in most true Desmidece. 
 
 58. COSMAEIUJNI Corda. 
 
 Char. Frond constricted in the middle. Segments frc- 
 quently as broad and sometimes broader than long, neither 
 
362 DESMIDE^. 
 
 notched nor lobed, but mostly either denticulated or dotted, 
 almost touching each other. 
 
 Derivation. From /cocrfiapiov, a small ornament. 
 
 The form of the frond in this genus is much more simple 
 than that of most of the other genera of Desmidece, being 
 neither notched nor lobed. The genus to which it is most 
 closely allied is Xanthidium, from which it chiefly differs in the 
 minuteness of the spines or teeth, which are placed on the 
 outer surface of the frond in most species, as well as in the 
 absence of the lateral apertures noticed in Xanthidium fur- 
 catum and X. aculeatum. Through Closterium cylindricum, 
 it exhil^its some relation to the genus Closteiium, in which 
 the form of the frond is also very simple ; but the two genera 
 are abundantly distinct. In Cosmarium the fronds are never 
 elongated nor curved as in Closterium, and they are always 
 constricted in the centre ; neither are they notched as in 
 Tetmemorus and Euastrum, nor lobed as in the latter genus, 
 nor compressed as in Micrasterias. 
 
 The denticulations observed on the surface of the fronds 
 of most species of the genus vary according to the age of the 
 specimens, being most strongly marked on the more fully de- 
 veloped examples. 
 
 a. Fronds denticulated. 
 
 1. Cosmarium margaritiferum Menegh. 
 
 Plate LXXXVI. Fig. 1. 
 
 Char. Fronds denticidated. Segments broader than long, 
 someivhat hemispherical or reniform, comjoressed. End 
 view elliptic. 
 /S Fronds dotted, but not denticulated. 
 
 Menegh. Synop. Desmid. in Linnrea, 1840, p. 219. Cos- 
 marium dentiferum Corda, Observ. IMicroscop. sur les 
 Animalc. de Carlsbad, p. 30. pi. vi. f 41. Euastrum 
 margaritiferum Ehr., Infus. p. 163. tab. 12. f. 7.; Pritch. 
 
COSMARIUM. 363 
 
 Infus. p. 196. f. 126.; Bailey, Amer. Bacil. in Am. 
 Journ. of Sciences and Arts, vol. xli. No. 2. p. 295. fig. 8. 
 UrsincllamargaritiferaTxxr-^., Diet, des Sc. Nat. (1820). 
 Hetei'ocarpclla Ursinella Kiitz., Syn. Diatom, p. 598. 
 Cymbella rcniformis Ag., Consp. Diatom, p. 10. ; Grev. 
 in Hook. Br. Flor. vol. ii. p. 415. ; Harv. Brit. Alg. 
 p. 215. Cosmarium margaritiferum Ralfs, in Annals of 
 Nat. Hist. vol. xiv. p. 393. pi. xi. fig. 4. ; Jcuner, in 
 loc. cit. p. 1 94. 
 
 Hah. In bogs and pools, &c. common ; Weston bogs, 
 near Sovitliampton, and numerous habitats in Sussex 
 and Kent : Mr. Jenner. Farnham, Surrey : Mr. Reeves, 
 Cheshuut, Herts : A. H. H. Near Bristol : Mr. Tliwaites. 
 Barmouth : Bev. T. Salwey. DolgeUy, Carnarvon, and 
 Penzance : Mr. Ralfs. 
 
 This species varies considerably in size, form, and in the 
 number and degree of developement of the spines, which 
 cover the frond. Each segment may be compared in form 
 to a kidney. It is the most abundant species of the genus. 
 Ehrenbcrg figures the denticles as placed in regular series 
 or rows, which in some specimens I have seen to be the 
 case. 
 
 2. Cosmarium Botrytis Mencgh. 
 Plate LXXXVI. Fig. 2. 
 
 Char. Frond denticulated, cojiipresscd. Segments trnncoto- 
 triaiigidar. End view elliptic. 
 C. Botrytis INIeneg., Synop. Desmid. p. 220. Buastrum Bo- 
 trytis Ehr., Infus. p. 163. tab. xii. fig. 8. C. Botrytis 
 Ralfs, in Annals of Nat. Hist., vol. xiv. ph xi. fig. 5. 
 Heterocarpella Botrytis Bory, in Diet. Classique, 1825. 
 Euastrum angidosum Ehr., Infus. tab. xii. fig. 8. Cos- 
 marium deltoides, in part, Corda, Almanac, de Carlsbad, 
 1835, p. 205. 
 
 Ilab. Near Bristol : M?-. Tliwaites. Sussex : 3fr. Jenner. 
 
364 DESMIDE^. 
 
 Near Manchester: Mr. Sidehotham. Dolgelly: Mr. 
 Ralfs. High Beech: A.H.H. 
 
 A very clistinct species. The frond is usually about a 
 third less than that of Cosmarium margaritiferum. 
 
 3. COSMARIEM ORNATUM Ralfs. 
 
 Plate LXXXVI. Fig. 3. 
 
 Char. Frond denticulated. Segments hroader than long. 
 Front view curved at the sides, hut truncate at the extremi- 
 ties. End view, four-lobed. 
 
 Cosmarium ornatum Ralfs, in Annals, vol. xiv. p. 392. pi. xi. 
 fig. 3. ; Jenner, in Fl. of Tunbridge Wells, p. 194. 
 
 Hah. In boggy pools about Dolgelly and Barmouth: 
 Mr. Ralfs. Ashdown Forest, Sussex : 3Ir. Jenner. 
 Cheshunt Common : A. H. IL 
 
 This species is likewise very distinct, and there can be no 
 danger of confounding it with any other liithcrto described. 
 The fronds are about as large as those of C. margaritiferum, 
 the four-lobed form of the segment when viewed endways is 
 l^eculiar to the sjjecies ; this form is occasioned by the central 
 inflation of each segment, 
 
 4. Cosmarium orbiculatum Ralfs. 
 
 Plate LXXXVI. Fig. 5. 
 
 Char. Segments minute^ nearly spherical, hotli in front and 
 end vieics. 
 Cosmarium orhicidatum Ealfs, in Annals, vol. xiv. p. 392. 
 
 pi. xi. fig. 2. 
 Hah. Boggy pools, near Dolgelly : Mr. Ralfs. Near 
 Manchester : Mr. Sidehotham. 
 
 A distinct little species, and the smallest of tlie genus. 
 
COSMARIUM. 365 
 
 5. COSMARIUM CYLINDRICUM Ralfs. 
 
 Plate LXXXVI. Fig. 4. 
 
 Cha7\ Fronds small, finely denticulate. Segments longer 
 than broad, in the front view, suhquadrate, broadest at the 
 extremity, narroioer at their junction. End view cir- 
 cular. 
 
 Cosmarium cylindricum Ralfs, in Annals, vol. xiv. pi. xi. 
 
 f. 1. 
 Hah. Mixed with other Alga on the wet sides of a cave 
 
 at Laurarna Cove near Penzance : 3Ir. Ralfs. 
 
 The fronds are minute, and about twice as long as broad. 
 Segments united along their entire breadth, so that no 
 notches are formed at the sides. 
 
 b. Fronds mostly punctated or smooth. 
 
 6. Cosmarium crenatum Ralfs. 
 
 Plate LXXXVI. Fig. 6. 
 
 Cha7\ Fronds punctated. Segments broader than long, com- 
 pressed, somewhat triangular, with the margins deej)ly cre- 
 nated. End view elliiitic, 
 C. crenatum Ealfs, in Annals, vol. xiv. pi. xi. fig. 6. ; Jen- 
 ner, loc. cit. p. 196. 
 
 Hah. Weston bogs, near Southampton, and several stations 
 in Sussex : Mr. Jenner. Near Bristol : Mr. Thwaites. 
 Near Manchester : Mr. Sidebotham, Dolgelly and Pen- 
 zance : Mr. Ralfs. 
 
 "This plant very much resembles a young specimen of 
 C. margaritifcrum ; but as the margin is always strongly 
 crenated, even in the earliest stage, and the surfoce is punc- 
 tated and not granulated, I am induced to describe it as dis- 
 tinct." — i?a/A. 
 
366 DESMIDEJE. 
 
 7. COSMARIUM OVALE Raljs. 
 
 Plate LXXXVI. Figs. 8. and 9. 
 
 Chai\ Fronds large, compressed, punctated. Segments tri- 
 angular, slightly truncate at the extremity. End view 
 broadly elliptic. 
 /3 Segments dentated, 
 
 Cosmarium ovale Ralfs, in Annals, vol. xiv. pi. xi. fig. 7. — 
 /3. Euastrum No. 6. Bailey, 1. c. p. 295. fig. 28. ; Jen- 
 ner, in loc. cit. p. 196. 
 Hab. Dolgelly : Mr. Ralfs. Barmouth : Rev. T. Salwey. 
 Near Tunbridge Wells, in a pond between Eamlye and 
 Broadwater Forest ; Beckley Furnace : Mr. Jenner. — 
 /3. Weston bogs, near Southampton : Mr. Jenner. 
 
 The characters of the different species of Desmidem may 
 generally be so accurately embodied in the definition as to 
 preclude the necessity of any lengthened remarks attached to 
 each species ; this conciseness it is to be hoped as our know- 
 ledge of the works of creation becomes more extensive, will 
 be found applicable to the descri^^tion of all organised pro- 
 ductions. 
 
 8. Cosmarium Cucumis Corda. 
 
 Plate LXXXVI. Fig. 10. 
 
 Char. Fronds orbicular, ?mich compressed. Segments hemi-^ 
 spherical, quite smooth, being neither denticulated nor dotted. 
 End view elliptico'lanceolate. 
 
 Menegliini, Synops. Desmld. p. 220. Euastrum integerri- 
 mum Ehr., Infus. p. 163. tab. 12. fig. 9. Cosmarium 
 Cucumis Corda, Almanac de Carlsbad, 1835, p. 206. 
 tab. 11. figs. 27, 28. C. Cucumis Ralfs, 1. c. p. 395. pi. xi. 
 fig. 8.; Jenner, in loc. cit. p. 196. 
 
 Hab. Sussex : Mr. Jenner. Dolgelly : Bfr. Ralfs. 
 
 The frond is more orbicular and not punctated as in Cos- 
 marium ovale. 
 
CLOSTERIUM. 367 
 
 9. COSMARIUM QUADRATUM Ralfs. 
 
 Plate LXXXVI. Figs. 11. and 12. 
 
 Chai', Fronds about twice as long as broad. Segments qua- 
 drate, in front view sliglitly compressed, smooth. 
 
 Kalfs, 1. c. vol. xlv. t. 11. f. 8. ; Jenner, 1. c. p. 196. 
 Hab. Eustliall Common, near Tunbridge AVells : Mr. 
 Jenner. Dolgelly : Mr. Ralfs. 
 
 The front view of the segments is somewhat quadrangular, 
 the distal or free angles being slightly rounded, and the 
 proximate, protuberant. 
 
 10. COSMARIUM CUCURBITA Brcb. 
 
 Plate LXXXVI. Fig. 7. 
 
 Char. Fronds small, about twice as long as broad, cylindrical, 
 
 with a slight constriction in the centre, minutehj jninctated. 
 
 End view circular. 
 Ralfs, in Annals, vol. xiv. ; Jenner, in Flora of Tunbridge 
 
 Wells, p. 196. Cosmarium Cucurbita Desm., No. 1103. 
 Hab. Dolgelly ; Mr. Ralfs. Ashdown Forest and 
 
 Greatham bogs, near Pulborough : 3Ii\ Jenner. 
 
 This species approaches rather closely to Cosmarium cylin- 
 drum Ralfs, but the frond in that species is distinctly den- 
 tated, whereas in C. Cticurbita Brcb. it is merely dotted : 
 it also has a great resemblance to Clostcrium cylindrus, but in 
 that plant the puncta are described as arranged in longitudinal 
 lines, whereas in Cosmarium Cucurbita they are scattered. 
 
 59. CLOSTERIUM Nitzsch. 
 
 Char. Fronds elongated, mostly crescentic, sometimes con- 
 jugating; each formed of two similar segments, ichich 
 unite without constriction, and the free extremity of each 
 
368 DESMIDE^. 
 
 of which is occupied by a vesicle filled with active mole- 
 cules. 
 
 Derivation. From Kkcoar'qp, a fine thread ; in allusion to 
 the attenuated form of the frond. 
 
 The two peculiarities which distinguish the genus Clos- 
 terium from all other DesmidecB are the crescentic form of 
 the fronds and the i^resence in the free extremity of each 
 of the segments, of the vesicle filled with revolving particles. 
 These i}articles occasionallj escape from the vesicle, and cir- 
 culate vaguely and irregularly round the circumference of 
 the frond. The use of these particles is not determined : it 
 may be conjectured that they are in some way or otlier con- 
 nected with reproduction. 
 
 The existence of motive papillaj or processes issuing from 
 the open extremities of the segments has been denied by 
 most recent observers. 
 
 Conjugation has been noticed to occur by Ehrenberg in 
 Closterium Diance, CI. lineatum, CI. striolatum, and CI, 
 incequale. 
 
 Ehrenberg, by whom the genus ■Closterium is placed 
 amongst the poly gastric animalcula, thus defines it: — 
 
 " Animalia polygastrica anentera (tubo intestinali destl- 
 tuta) gymnica (non appendiculata), ct corpore uniformi in- 
 volucrato sen loricato, cryptomonadibus simillima, cum lorica 
 sponte et imperfecte dividua, hinc in polyparium bacilliforme 
 (aut fusiforme) abeuntia, j^apillis denique in lorica3 apertura 
 discretis. " 
 
 Independently of the irregular motion of the particles 
 escaped from the cells, a circulation has been noticed, con- 
 sisting of two opposite currents, the one along the side of the 
 shell, and the other along the periphery of the internal gela- 
 tinous matter, which is invested with an elastic envelope. 
 
 By some systematists the Closteria are placed next to the 
 ConjugatecE, with which in the occasional conjugation of the 
 fronds of two Closteria and formation of sporangia they do 
 indeed exhibit a certain degree of relationship. 
 
 Through Closterium cylindrus Ehr., Infus. pi. v. fig. 6. 
 this genus would appear to be united to the genus Cosma- 
 
CLOSTERIUM. 369 
 
 riuni : it is most probable, however, that that species ought 
 to be referred to the latter genus. 
 
 a. Closteria curved, smooth, not appcndaged. 
 
 1. Closterium Ehrenbergii Menegli. 
 
 Plate LXXXVIL Fig. 1. 
 
 Char. Frond semilunar, thinned, and rounded at the ex- 
 tremities. Granules scattered. Endochrome fasciated. 
 Bands tivo or three in each segment. 
 
 Der halbe Mond, Eichorn, Kleinste Wassenthiere, p. 48. 
 taf. 5. fig. C. 1775, 1781, 1784. Vibrio Lunula INIuller, 
 
 , Naturforscher, 20. p. 142, 1784.; Herman (after Mul- 
 ler) ebenda, p. 169. taf. 3. fig. 59. V. Lunula Miiller, 
 Animalc. lufus. p. 5o. taf. vii. figs. 1 3. and 1 5. 1 7 1 7 ? Mul- 
 leria? i?/?«^ZaLeclerc, 1802 ? Confci^ve inedite, l^o. 11 , 
 (^Zr/gnemadeciminum) Gerod Chantrans, Keclierche sur les 
 Conferves, t.33. 1802. Mulleria Lunula Schrank, Fauna 
 boica, iii. 2. p. 47. 1803. Closterium Lunula l^'xizsoh, 
 Beitriige, ^ Infusarienkunde, 60. and 67. 1817? Vibrio 
 Lunula Gruithuisen, Acta Nat. Curios, x. 2. p. 449. 
 1821. cfr. CI. moniliferum. Bacillaria Lunula, Acta l^at. 
 Curios, xi. 2. j). 533. 1823. Lunulina vulgaris Bor}^, 
 Encyc. Method. 1824, and in Diet. Class. d'Hist. mt. 
 1826. LAinulina vulgaris Turpin, Diet. d'Hist. Nat. 
 Planches Vegetaux, i. p. 3. 1828. Closterium Lunula 
 Hemprlch et Ehrenberg, Symbolaj Physica3, Ever- 
 tebrat. i. Phytozoa, tab. ii. iv. fig. 6. 1828. Closterium 
 Lunula, Isis, 1830, p. 168. Closterium Lunida, Abhandl. 
 der Academic d. Wissen.sch. zu Berlin, 1829, p. 7. 15. 
 1830, p. 40. 5Q. 62., 1831, p. 67. Closteritan Lunula, 
 Symbolic Physica3, text 1830 (1831), fol. b. a. 2. Clos- 
 terium Lunula Kiitz., Alga3 Aquat. siccatic, dec. iii. 
 No. 22. 1833, and Synopsis Diatomearum, Linnaja, 
 1833, 13. b9(S. Closterium Lunula and acuminatum Corda, 
 Almanac de Carlsbad, 1835, p. 190. tafel 5. L 5Q—Q0. 
 
 B B 
 
370 DESMIDE^. 
 
 Closterium Lunula, Aiinales des Sciences Naturelles, 
 1836, torn. V. Botanique, p. 263. tafel ix. x. a, xi. ; Jen- 
 ner, in Flora Tonbridgensis, p. 196. CI. Ehr enter gii 
 Menegh., Synops. Desmid. CI. Lunula Ehr., Die Infus. 
 t. V. f. 2. 
 
 Hah. Several places in Sussex : Mr. Jenner. Chesliunt : 
 A. H. H. 
 
 This species might readily be confounded with the next, 
 CI. moniliferu7n, in which the reproductive granules are in a 
 single series, and not scattered as in CI. Ehrenbergii. 
 
 The synonyms given require revision, on account of Ehren- 
 berg having confounded two species. 
 
 2. Closteuium moniliferum Ehr. 
 
 Plate LXXXVII. Fig. 2. 
 
 Char. Frond much curved. Apices thinned and rounded. 
 Granules disposed doicn the middle in a single series. En- 
 Aoq\vlOv:xq fasciated. Bands two or three. 
 
 Vibrio Lunula var. IMiiller, Animalc. Infus. p. 55. taf. 7. 
 fig. 8. 11. 1786. P. planzenthier Gruithuisen, Beitr. 
 ^ Physiognosie a Eautognosie, p. 322. t. ii. fig. 40. Clos- 
 terium Lunula Nitzsch, after Kiitzing, 1817. Lunulina 
 monilifera Bory, Encycloped. Method. 1824 ; Diet. 
 Classique d'Hist. Nat. 1826. Lunidina vulgaris Tur- 
 pin. Diet, des Sciences Naturelles, Planches Vegetaux, 
 i. F. 3. a. rechts, 1828. Closterium Lunula var., Abhandl. 
 der Akademie d. TVissensch. zu Berlin, 1831, p. 68. 
 Closterium lunula Kiitzing, Synopsis Diatomearum, Bot. 
 Zeitsch, Linna3a, v. Schlechtendal, p. 596. t.xviii. fig. 80. 
 1833. Closterium Lunula var. Morren ? Annales des 
 Sc. Nat. Botanique, torn. v. p. 337. planche xi. fig. 42. ; 
 Jenner, in Flora of Tunbridge Wells, p. 196. CI. Lei- 
 blinii INIenegh., loc. cit. 
 
 Hab. Framfield, Hillingly, Reigate, &c. : Mr. Jenner, 
 Chesliunt Common : A. H. H. 
 
CLOSTERIUM. 371 
 
 This species comes near to Closterium Dianas Elir., wliicli, 
 however, is a more elongated and more slender plant. 
 
 3. Closterium Dian^. Ehr. 
 
 Plate LXXXIV. Fig. 5. 
 
 Char. Frond slender, much attenuated toioards each end. 
 Granules in a single series doion the centre. Endochrome 
 fasciated. Fasciae obscure. 
 CI. riificeps, Abhandl. der Akademie d. Wlssench. zu Ber- 
 lin, 1831, p. 67. CI DiancB Ehr., Die Infus. p. 92. t. v. 
 f. 17. 
 Ilab. Chiltington Common, near Pulborough : 3Ii'. Jenner. 
 
 A distinct and elegant species. 
 
 b. Closteria curved, not appendaged, striated. 
 
 4. Closterium turgidum Ehr. 
 Plate LXXXVII. Fig. 3. 
 
 Char. Frond lai'ge, slightly curved, suhcylindrical, hut little 
 attenuated, very finely striated. Apices roundish and 
 rubescent. 
 Closterium turgidum Ehr., Infns. tafel vi. fig. 7. ; Jenner, 
 
 in Flora of Tunbridge Wells, p. 196. 
 Hah. Several places in Sussex : Mr. Jenner. 
 
 The stride in this species are finer, and the frond larger 
 than in Closterium striolatum. 
 
 5. Closterium striolatum Ehr. 
 
 Plate LXXXVII. Fig. 4. 
 
 Char. Frond fiisiform, gradually attenuated towards each 
 end, evidently striated, ten or tv-elve times as long as broad. 
 Extremities rounded. 
 
372 DESMIDE^. 
 
 Closterium striolatum, Abhancll. der Akademie d. Wisseiisch. 
 zu Berlin, 1831, p. 68. ; 1833, p. 238. Closterium cos- 
 tatum I and CI. spirale Corda, Almanac de Carlsbad, 
 1835, p. 191. taf. V. f. 61—63. and fig. 67. ? ; Ehr. In- 
 fus. p. 96. taf. 6. fig. 12. ; Jenner, 1. c. p. 196. 
 
 Hah. Several places in Sussex and Kent : Mr. Jenner. 
 Hertford Heath : A. H. H. Aberdeen : Dr. Dickie. 
 Galway: M'Colla. 
 
 This is a smaller species, more attenuated at the extre- 
 mities, and with strise more evident than in Closterium tur- 
 gidum. Each segment is occasionally divided by a transverse 
 line, as is well represented in one of the figures given by 
 Ehrenberg. 
 
 6. Closterium lineatum Ehr. 
 
 Plate LXXXVIII. Fig. 1. 
 
 Char. Frond very long, slender, slightly curved, in the centre 
 cylindrical and filiform, much attenuated at each extre- 
 mity, distinctly striated, often twenty times as long as 
 broad. 
 Closteriu77i lineatwn, Abhandl. der Akademie d. Wissensch. 
 zu Berlin, 1833 (1832), p. 238. ; Ehr. Infus. p. ^Q. t. 6. 
 fig. 8. ; Jenner, in Flora of Tunbridge Wells, p. 196. 
 Hab. Ashdown Forest : Mr. Jenner. 
 
 This is one of the most striking species of the genus ; the 
 granules are often arranged in single series, but sometimes 
 they are scattered. 
 
 7. Closterium Cornu Ehr. 
 Plate LXXXVIII. Fig. 2. 
 
 Char. Frond small, very slender, suhcylindrical, slightly 
 curved. Endochrome undulated. 
 Vibrio Lunula Miiller, Animalc. Infus. tab. vii. fig. 8. ? 
 Closterium Cornu, Abhandl. der Akademie d. Wissensch. 
 
CLOSTERIUM. 373 
 
 zu Berlin, 1830, j:*. G2. ; 1831, p. 67. Closterium tenue 
 Kiitzing, Synopsis Diatom, in v. Schlechtendal's Lin- 
 n»a, p. 525. tafel xviii. f. 78. ; Ehr. Infus. p. 94. taf. vi. 
 fig. 5. ; Jenner, in Flora of Tunbridge Wells, p. 196. 
 
 Hab. Piltdown Common; Mr. Jenner, 
 
 Apparently a very distinct little species. 
 
 c. Closteria appendaged, curved, striated. 
 
 8. Closterium rostratum JEh?-. 
 
 Plate LXXXVII. Fig. 6. 
 
 Char. Closterium fusiform, slender, slightly curved, striated, 
 much attenuated, appendaged, each horn scarcely equalling 
 the body in length, often much shorter. 
 Closterium rostratum, Abliandl. der Akademie d. Wis- 
 sensch. zu Berlin, 1831, p. 67. ; 1833, p. 240. Frustulia 
 suhtilis and subulata Kiitzing? Synops. Dcsmid. p. 538. 
 taf. xlii. fig. 3., 1833. Clostcriinn caudatum Corda, Al- 
 manac de Carlsbad, p. 190. 209. tafel v. fig. QQ., 1835 ; 
 Jenner, 1. c. p. 196. 
 Hab. Heathfield ; "\Yarbleton ; Waterdown Forest, &c. : 
 Mr. Jenner. High Beech : A. H. H. 
 
 A singular but not uncommon species. 
 
 9. Closterium setaceum Ehr. 
 
 Plate LXXXVII. Fig. 7. 
 
 Char. Frond fusiform, setaceous, straight, or very slightly 
 curved, faintly striated, appendaged, appendages longer 
 than the frond itself. 
 Closterium setaceum, Abhandl. der Akad. d. Wissenscli. 
 
 zu Berlin, 1833, p. 239.; Jenner, in loc. cit. p. 196. 
 Hab. Waterdown Forest, and near Cross in Hand : Mr. 
 Jenner. Cheshunt Common : A. H. H. 
 
374 DESMIDE^. 
 
 This species differs from the previous one in being much 
 smaller, more finely striated, and having longer setaceous 
 
 d. Closteria smooth, not apjjendaged, straight. 
 
 10. Closterium Lunula Ehr. 
 
 Plate LXXXIV. Fig. 4. 
 
 Char. Frond fusiform, ventricose, toith rounded extremities. 
 Granules numerous, scattered. Endochrome fasciated, 
 bands usually three. 
 CI. Lunula Ehr., Die Infus. t. v. figs. 1. and 3. C. Lunula 
 Menegh., Synops. Desmid. 
 
 Hah. Beckley Furnace: Mr.Jenner. High Beech: A.H.H. 
 
 This species I noticed when examining some Pediastra 
 kindly sent me by Mr. Jenner. It is figured by Ehrenberg 
 as a state of Closterium Lunula, and indeed Meneghini regards 
 it as that species, conferring the name of Ehrenberg upon 
 what better agrees with the name of Lunula, and with 
 Ehrenberg's description, although this last is evidently so 
 contrived as to embrace both species. The frond, in Mr. 
 Jenner's specimens, was not of the gigantic size figured by 
 Ehrenberg. 
 
 11. Closterium acerosum ^Ar. 
 
 Plate LXXXVII. Fig. 5. 
 
 Char. Closterium fusiform, gradually attenuated towards 
 each extremity. Granules in a single series down the 
 centre of the frond. Endochrome handed. 
 
 Corpicetti a haccillo Corti? Observaz. Micros, p. 111. t. 11. 
 fig. 17. i. g. and r. s., 1774. Vibrio Lunula Miiller, Ani- 
 malc. Infus. taf. 7. f. 12., 1786. Vibrio acerosus Schrank, 
 Fauna boica. 111. 2. p. 47., 1803. Baccillaria multistriata 
 Hempritch et Ehrenberg, Symbola3 Physics, Phytozoa, 
 
CLOSTERIUM. 375 
 
 pi. ii. Sanaitica, f. 9. 1828. Closterium multistriatum, 
 Abliandl. cler Akademie d. Wissensch. zu Berlin, 1829, 
 p. 15 — 20. Closterium acerosum, Symbolaa Physica3, 
 Evertebrata, text 1830 (1831); Polygastrica, fol. b. 
 a. 2. Closterium acerosum, Abhandl. der Akademie d. 
 Wissensch. zu Berlin, 1831, p. 68. Closterium Lunula 
 Morren, fig. 43. ; Ehr. Infus. p. 93. pi. vi. fig. 1. Cijm- 
 bella IIoj)/{irkii Moore, in Ord. Survey ; Harv., in 
 Manual, p. 215. CI. acerosum Jenner, in Flora of 
 Tunbridge Wells, p. 196. Co7if. ovata, Flora Glottiana. 
 Hab. Near Glasgow : il/r. Hopkirk. About Lisburn and 
 in one of the caves, Cave Hill, Belfast : 3Ir. Moore. 
 Warbleton, &c. : Mr. Jeiiner. Gal way : 3I'Colla. 
 There is no species hitherto described Avith which it is 
 necessary that this should be compared, the straight and 
 fusiform frond rendering it clearly distinct from all other re- 
 corded species. This species was named by Mr. ]\loore Cym. 
 Ho2)MrMi, in memory of INIr. Hopkirk, author of " Flora 
 Glottiana." 
 
 e. Closteria straight, not lunar. 
 
 12. Closterium Trabecula Ehr. 
 Plate LXXXVIII. Fig. 3. 
 
 Char. Frond broad, longitudinallij symmetrical, somewhat 
 quadrangidar. Granules scattered or disjjosed in several 
 series. ^n(\ochvon\Q fasciated. Bands several. 
 Closterium Trahecida, Abhandl. der Akademie d. Wis- 
 sensch. zu Berlin, 1830, p. 62. 70. ; 1831, p. 68.; Ehr. 
 Infus. 93. pi. V. fig. 2. ; Jenner, in Flora of Tunbridge 
 Wells, p. 196. 
 Hab. Busthall Common ; Piltdown Common ; Scrubbs, 
 Colebrookc Park ; Waterdown Forest : Mr. Jenner. 
 
 This Closterium bears some resemblance in form at least to 
 CI. margaritaceum, but diflxirs from that species in being 
 altogether much larger, in its entire margins and in the posi- 
 
376 DESMIDE^. 
 
 tion of the vesicles containing the active molecules, which in 
 Closterium Trabecida as in all other Closteria hitherto de- 
 scribed are placed near to each extremity of the frond. 
 
 13. Closterium margaritaceum Eh7\ 
 
 Plate LXXXVIIL Fig. 5. 
 
 Char. Frond ci/Imdrical, narrow, two to eight times as long as 
 broad, someiohat quadrangular, often slightly constricted, 
 striated. Stride denticulated. Cells containing the revolving 
 particles distant from each extremity. 
 
 Ehr. lufus. p. 93. pi. v. fig. 13. ; Jenner, inloc. cit. p. 196. 
 
 Hab. Piltdown Common ; "VYarbleton ; and in the pond 
 between Ramslye and Broadwater Forest : Mr. Jenner. 
 
 A distinct and very interesting little species : it is some 
 eight or ten times smaller than CI. Trabecula. 
 
 14. Closterium Digitus Ehr 
 Plate LXXXVIIL Fig. 4. 
 
 Char. Frond broad, ovate, cylindrical, four or five times 
 as long as broad; transverse lines of division sometinies 
 triplex. Endochrome^a^cmfec/. Bands ^ye or six, often 
 ivaved. 
 Closterium digitus, Abhandl. der Akademie d. Wissensch. 
 zu Berlin, 1831, j). Q'^. Pleurosicyos 3Iyrio(j)o')dus 
 Corda, Almanac de Carlsbad, 1835, p. 182. t. 5. f. 68, 
 69. CI. Digitus 9 Menegh., 1. c. p. 236. 
 Hab. Bogs at Fisher's Castle, Ashdown Forest ; Scrubbs, 
 Colebrook Park, and between Heathfield and Warble- 
 ton : BIr. Jenner. Aberdeen : Br. Dickie. 
 
 This is one of the finest and most distinct of the nume- 
 rous species described by Ehrenberg, whose figures of Clos- 
 teria are most beautiful and accurate, and Avhose descriptions 
 are not less so. The species of this genus being for the most 
 
TETMEMORUS. 377 
 
 part of considerable size do not require for their satisfactory 
 examination the high and delicate powers with which most of 
 the Dcsmidece need to be examined. 
 
 60. TETMEMORUS Ralfs. 
 
 Char. Frond elongated, straight, suhcylindrical, slightly con- 
 stricted in the centre. Segments emarginate at their ex- 
 tremities hut otherwise entire, being neither lohcd nor 
 sinuated. 
 Derivation. From ts/jlvco, to cut. 
 
 The two species for the reception of which this genus has 
 been created are placed by Meneghini in the genus Closteriian 
 with the other species of which they do not well accord. 
 
 From Closterium it differs in the emarginate extremities of 
 the segments, and in the absence of the cells containing the 
 revolving particles : from Cosmarimn it is separated by the 
 divided segments, as well as by its elongated fronds. 
 
 From Euastrum, with which it agrees in the terminal 
 division of the segments, it differs in being neither lobed nor 
 sinuated. 
 
 1 . Tetmemorus Brebissoni Ralfs. 
 Plate LXXXIX. Fig. 5. 
 
 Char. Frond about Jive times as lojig as broad, considerably 
 constricted in the centre. Segments in the front view 
 somewhat quadriform, but zn the lateral vieio attenuated, 
 longitudinally striated. Granules in a roio dmcn the 
 centre of the frond. 
 Closterium Brebissoni IMenegh., Syn. Desmid. in Linna?a, 
 1840, p. 236. Closterium (sp. 9.) Bailey, American 
 Bacillaria, in Amer. Jour, of Science and Arts, vol. xli. 
 No. 2. pi. i. fig. 38. Tetmcmorus Brebissoni Ralfs, 
 Ann. vol. xiv. p. 258. pi. viii. fig. I. ; Jenncr, in Flora 
 of Tunbridge Wells, p. 198. 
 
378 DESMIDE^. 
 
 Hah. Bogs at Fisher's Castle ; Waterdown Forest ; Pilt- 
 down Common ; Cross in Hand, &c. : Mr. Jenner, 
 Dolgelly, Caermarthen, and Penzance: Mr. Rolfs. 
 High Beech : A. H. H. Aberdeen : Dr. Dickie. 
 
 The fronds when empty are found to be minutely punc- 
 tate, the puncta being arranged in longitudinal rows. It 
 differs from Tetmemorus granulatus in its form altogether 
 and in its puncta arranged in longitudinal lines. 
 
 2. Tetmemorus granulatus Ralfs. 
 Plate LXXXIX. Fig. 6. 
 
 Char. Frond six or seven times as long as broad, taperijig 
 both in front and lateral views, hut slightly constricted 
 in the centre. Segments rounded at the extremities 
 and terminating i?i a colourless, projecting, lip-like pro- 
 cess, punctated. Puncta arranged in diagonal lines. 
 Granules in a row down the centre of the frond. 
 Closterium granulatum Breb., in JMenegh. Synop. Desmid. 
 p. 236. Tetmemorus granulatus Palfs, in Annals of 
 Nat. Hist., vol. xiv. p. 257. pi. ^dii. fig. 2. T. granu- 
 latus Jenner, in Flora of Tunbridge Wells, p. 198. 
 Hah. Bogs at Fisher's Castle ; Scrubbs, Colebrook Park, 
 Waterdown Forest; Ashdown Forest, and Cross in 
 Hand : Mr. Jenner. Dolgelly and Penzance : Mr. Ralfs. 
 High Beech : A. H. H. Aberdeen : Dr. Dickie. 
 
 Tetmemorus granulatus differs from the preceding species 
 in several respects. In the form of the frond, which is alto- 
 gether different, being quadriform in T. Brehissoni, and fusi- 
 form in the present species, in the remarkable lip-like pro- 
 jection of the extremities of the segments, and in the arrange- 
 ment of the puncta in diagonal and not longitudinal lines. 
 Near the junction of the segments the puncta are observed 
 to be arranged in three or four transverse lines. 
 
 This species has been found by Mr. Kalfs in a state of 
 conjugation, and with the sporangium formed similar to that 
 
EUASTRUM. 379 
 
 of numerous Closteria, and not differing from that of Stau- 
 rocarpus amongst the Conjugates. The steps of the form- 
 ation of this in Closterium and Tctmemorus are as follow. 
 Two fronds coalesce, a cell is gradually formed between 
 them into which the endochrome passes from each frond 
 and Avhicli finally becomes moulded into a distinct organ or 
 sporangium invested with its membrane. 
 
 61. EUASTRUM Ehr. 
 
 Char. Frond compressed^ deeply divided into tivo segments. 
 Segments longer than Iroad, usually pyramidal, emar- 
 ginate at their extremities, and lohed and tubercidated or 
 sinuated. 
 Derivatio7i. From sv, beautiful, and aarpov, a star. 
 
 " In this genus Ehrenberg includes JSIicrasterias Ag. (not 
 3Iicrasterias Ehr.) and Cosmarium ; JNIeneghini separates the 
 former from it, but includes it in the latter genus. Euastrum 
 appears to me to be distinct from both, aiad especially from 
 Cosmarium. It agrees with Micrasterias in having lobes and 
 emarginate ends ; but the fronds are not incised, nor do the 
 lobes radiate from the centre. From Cosynaiiuyn it differs in 
 the lobed and emarginate segments, and also in the inflated 
 projections on the surface. These characters will also dis- 
 tinguisli it from the other genera of this family." — Ralfs.* 
 
 a. Segments of the frond deeply lohed, tuherculated. Terminal 
 lobes cuneate. 
 
 1. Euastrum verrucosum Ehr. 
 
 Plate XCI. Fig. 7. 
 
 Char. Frond denticulated. Segments three-lohcd. Lobes 
 broad, subcuneate, tcith a broad shallow notch bcticeen each 
 lobe. 
 Euastrum verrucosum, Abhand. der Akademie d. Wissensch. 
 
 * Annals, vol. xiv. p. 188. 
 
380 DESMIDEJiJ. 
 
 zu Berlin, 1833 (1832), p. 247.; Ehr. Infus. p. 162. 
 pi. xii. fig. 5.; Kalfs, in Annals, vol. xlv. pi. vi. fig. 3.; 
 Jenner, in Fl. Tunb. Wells, p. 198. ; Pritch. Infus. 
 p. 196. fig. 125. Cosmarium verrucosum Menegh., 
 Synops. Desmid. in Linn^ea, 1840, p. 222. 
 Hah. Chesliunt : A. H. H. Rusthall Common, and Ash- 
 down Forest : Mj\ Jenner. Penzance : Mr. Ralfs. 
 
 Tills is a very distinct species and the only British one of 
 the genus Avhich has a dentated frond. 
 
 2. EUASTRUM OBLONGUM Ralfs. 
 
 Plate XCI. Fig. 1. 
 
 Char. Frond large, smooth, ohlong, oval, dotted, three or four 
 times longer than broad. Segments in front view Jive- 
 lobed, semi- oval ; lobes hroad, suhcuneate, emarginate : in 
 lateral y'lcvf pyraiyiidal, furjiished ^cith six tubercles each. 
 Euastrum pecten, Abhandl. der Akademie d. Wlssensch. zu 
 Berlin, 1831, p. 82. Euastrum pecten Ehr,, Infus. p. 162. 
 pi. xii. fig. 4. ; Pritch. Infus. j). 196. Echinella oblonga 
 Grev., in Hook. Br. Fl. vol. ii. p. 398. (1830). Cos- 
 marium ohlongum Menegh., 1. c. p. 221. Eutomia oblonga 
 Harv., Man. Br. Al. p. 188. ; Ralfs, in Annals, vol. xlv. 
 p. 189. pi. V. fig. 4. ; Jenner, in Fl. Tunbrldge Wells, 
 p. 198. 
 
 Hab. Bogs at Fisher's Castle ; Rusthall Common ; War- 
 bleton, &c., Beckley : 3Ir. Jenner. Penzance, Dolgelly, 
 and Caernarvon : Mr. Ralfs. Aberdeen : Dr. Dickie. 
 High Beech: A. H. H. 
 
 This is the finest species of the genus, and a beautiful 
 microscopic object, as are most of the species of this genus. 
 
 3. Euastrum Pelta Ralfs. 
 
 Plate XCI. Fig. 3. 
 
 Char. Frond three times as long as broad, subquadrilateral. 
 
EUASTRUM. 381 
 
 compressed, dotted. Segments m front view three-lohed; 
 lateral lobes each twice slightly emarginate : in lateral view 
 much compi^essed. 
 Cosmarium Pelta Corda, Almanac de Carlsbad, p. 121. C. 
 Pelta INIenegh., Synops. Dcsmid. p. 222. Eiiastrum 
 Pelta Ralfs, in Annals, vol. xiv. pi. vii. f. 1. ; Jenner, 
 loc. cit. p. 198. 
 Hab. Bogs at Fisher's Castle and on Ashdown Forest ; 
 Piltdown Common : Mr. Jenner. Dolgelly ; Penzance : 
 Mr. Ralfs. High Beech : A. H. H. 
 
 There is no other species with which this need be con- 
 trasted. 
 
 4. EUASTEUM DiDELTA Ralfs. 
 
 Plate XC. Fig. 8., and Plate XCI. Fig. 11. 
 
 Char. Frond about three times os long as broad, dotted. 
 Segments in front view pyramidal, and laterally 7i$ually 
 twice emarginate ; in ixa.x\s\erse. somewhat four-lobed, and 
 in end view oval. 
 
 Heterocarpella Didelta Turp.,Mem. p. 295. (1828). Hetero^ 
 carpclla polymorpha Kiitz., Synops. Diatom, in Linnosa, 
 1833, p. 70. fig. 82. Euastrum ansatum, Abhandl. d. 
 Akademie Wissensch. zu Berlin, 1831, p. 82. ; Ehr. 
 Infus. 13. 162. t. 12. fig. 6. Cosmarium lagenarium. Al- 
 manac de Carlsbad, 1835, p. 206. pi. ii. fig. 26. Cos- 
 marium Didelta Menegh., 1. c. p. 219. Euastrum Didelta 
 Ralfs, in Annals, vol. xiv. pi. vii. fig. 2. ; Jenner, in Flora 
 of Tunbridge Wells, p. 198, 
 
 Hab. Frequent in Sussex : Mr. Jenner. Hcnfield : Mr. 
 Borrer. Cheshunt : A. H. H. Barmouth Eoad : Rev. 
 T. Sahcey. Caernarvon ; Dolgelly, near Carmarthen ; 
 and Penzance : Mr. Ralfs. Aberdeen : Dr. Dickie. 
 
 A very distinct species. 
 
382 DESMIDE^. 
 
 5. EUASTRUM AFFINE Ralfs. 
 
 Plate XC. Fig. 9. 
 
 Char. Frond about three times as long as broad. Segments 
 pyramidal in front view, a)id thrice emarginate ; in lateral 
 view tivice emarginate. 
 /3 Frond about once and a half as long as broad, twice 
 
 emarginate. 
 Euastrum affine Ralfs, in Annals, vol. xiv. pi. vii. fig. 3. 
 
 Hah. In peat pools near Dolgelly : 3Ir. Ralfs. High 
 Beech : A. H. H. Aberdeen : Dr. Dickie. 
 
 Fronds about as large as those of Euastrum Didelta ; the 
 segments somewhat resemble a decanter in form ; the base 
 is broad and inflated, and contracted upwards into a wide neck ; 
 the terminal notch is deep but not gaping ; the body of the 
 segment is broadly emarginate on each side ; all the lobes or 
 projections are rounded and the sinuses shallow. 
 
 The var. (3 is probably distinct. 
 
 6. Euastrum gemmatum Ralfs. 
 
 Plate XCI. Fig. 6. 
 
 Char. Frond rather more than ticice as long as broad. Seg- 
 ments in front view scarcely emarginate at their extremi- 
 ties, laterally ticice so ; in transverse view eight-lobed, 
 longer than broad; and in end xievf four-lobcd. 
 
 /3 Terminal lobe emarginate at each side. 
 
 Cosmarium gemmatum ^reh., Menegh. 1. c. p. 221. Euas- 
 trum gemmatum Ealfs, Ann. vol. xiv. p. 191. pi. vii. 
 fig. 4. ; Jenner, in Flor. Tunbridge Wells, p. 198. 
 
 Bab. Near Dolgelly : 3Ir. Ralfs. Scrubbs, Colebrook 
 Park, and on Ashdown Forest, in the great bog near 
 Forest Bow : Mr. Jenner, 
 
 "Fronds rather smaller than those of E. Didelta, nearly 
 three times as long as broad. Each segment consists of a broad 
 basal portion which is somewhat quadrilateral and emarginate 
 
EUASTRUM. 383 
 
 at each side, and suddenly contracted to form the very short 
 neck ; the terminal lobe has each side elongated and rounded 
 entire in a and slightly eraarginated in /3; the terminal 
 notch is vei'y obscure. The transverse view is twice as long 
 as broad, with two rounded projections at each end, and three 
 on each side, and a small central opening at the original 
 junction-jjoint of the segments." — Ralfs. 
 
 7. EUASTRUM CIRCULARE Hass. 
 
 Plate XC. Fig. 5. 
 
 Char. Frond about twice as long as broad, small, smooth; 
 each segment anteriorly occupied tvith seven tubercles. Jive 
 at the basal, and two at the distal extremity, four of the 
 Jive basal tubercles disposed in a half circle around the fifth. 
 
 Hob. High Beech : A. H. H. 
 
 A very distinct little species. 
 
 b. Segments xmtli acute angles, sometimes prolonged into spi7ious 
 processes not generally tuberculated. 
 
 8. EUASTRUM ROSTRATU3I Ralfs. 
 
 Plate XCI. Fig. 8. 
 
 0iar. Basal lobes of the segments broad and emarginate. 
 
 Terminal lobe tcith a curved acute spine-like process on 
 
 each side. 
 Euastrum rostratum Ealfs, in Annals, vol. xiv. pi. vii. f. 5. 
 Hab. In freshwater pools near Dolgelly : 3Ir. Ralfs. 
 
 " Frond very minute, about twice as long as broad ; seg- 
 ments obscurely three-lobcd, or rather with a broad base, 
 which is emarginate on each side, and then contracted into a 
 broad short neck, connecting it with the terminal lobe. The 
 terminal portion has on each side a curved subacute tubercle 
 or process, somewhat like a beak ; the end of the lobe is 
 prominent, generally angular, with a deep rounded terminal 
 notch." 
 
384 DESMIDE^. 
 
 9. EUASTRUM SPINOSUM Balfs. 
 
 Plate XCI. Fig. 9. 
 
 Char. Frond minute, somewhat oval, compressed, rather better 
 
 than twice as long as broad. Segments twice emarginate 
 
 at the side. Angles often spinous, especially the distal 
 
 ones. 
 Euastrum spinosum Ralfs, in Annals, vol. xiv. p. 192. pi. 
 
 vii. fig. 6. ; Jenner, Flor. Tunbridge Wells^ p. 198. 
 Hah. Cheshunt : A. H, H. Barmouth : Rev. T. Salwey. 
 
 Mayfield ; Rustliall Common ; Piltdown Common ; 
 
 Chiltington Common ; and Rackham, near Pulborougli ; 
 
 Dolgelly ; Penzance : Mr. Ralfs. 
 
 A distinct thougli variable little species, and one by no 
 means uncommon. 
 
 10. Euastrum binale Ralfs. 
 Plate XCI. Figs. 4, 5. 
 
 Char. Frond about twice as long as broad. Segments con- 
 cave or truncate, at the end not projecting beyond the acute 
 angles. 
 a " Segments inflated at the base, the notch broad, forming 
 
 a concavity between the angles.^'' 
 /3 truncatum. — " YYon^s quadrilateral ; the end truncate, 
 acute at the angles, loith a small triangular notch in 
 the middle ; " segments laterally tioice crenate. 
 Heterocarpella biiialis Turp., Kiitzing, Synops. Diatom, p. 
 70. Cosmarium binale Menegh., Syn. Desmid. p. 221.; 
 Ralfs, in loc. cit. ; Jenner, in loc. cit., p. 198. 
 Hab. Mayfield ; Piltdown Common, and bog near Cross 
 in Hand : Mr. Jenner. Dolgelly ; Penzance : 3Ir. 
 Ralfs. 
 
 The variety /3 may prove to be distinct. 
 
MICRASTERIAS, 385 
 
 62. MICKASTERIAS Ag. 
 
 Char. Frond compressed, deeply divided into two segments. 
 Segments lobed, radiant, and incised. 
 Derivation. From fxiKpos, small, and aa-Tspvas, starred. 
 
 The flat and orbicular fronds, and the radiant and incised 
 lobes, will distinguish this at once from all other genera of 
 Desmidece. 
 
 The genus Micrasterias of Agardh differs entirely from the 
 Micrasterias of Ehrenberg, which has been referred to the 
 Pediastrum of Meyen. 
 
 1. Micrasterias rotata Ag. 
 
 Plate XC. Fig. 1. 
 
 Char. Fronds smooth, orbicular, ten-lobed. Lobes cuneate, 
 approximate, the end lobe cmarginate, the others bifid, the 
 divisions being notched. 
 
 JSIicrasterias rota Menegh., Synops. Desmid. in Linnaia, 
 1840, p. 215. Echinella rotata Grev., in Hook. Br. 
 Flora, vol. ii. p. 398. (1830). FAitomia rotata Harv., Br. 
 Alg. p. 187. Euastrum rota Ehr., Infus. p. 167. tab. 12. 
 fig. 1.; Pritch. Infus. p. 195. figs. 121—123.; Bailey, 
 American Bacillaria, pi. i. fig. 22. and fig. 24. Micra- 
 sterias Ag., Bot. Zeit. 1827. ? Cosmarium stellinum et 
 C. truncatum Corda, Almanac dc Carlsbad, 1835, p. 206. 
 pi. ii. pp. 22, 23. ; Ealfs, in Annals, vol. xiv. ; Jeuner, in 
 loc. cit. p. 198. 
 
 Hah. Frequent in Sussex : Mr. Jenner. Henfield : Mr. 
 Borrer. About Barmouth : Bev. T. Salicey. Aber- 
 deen : Dr. Dickie. Stevenston, Ayrshire : Rev. D. 
 Landsborough. Penzance ; Dolgelly ; &c. : Mr. Ralfs. 
 Cheshunt Common : A. H. H. 
 
 The frond of this species in its young condition differs so 
 much from the adult form that it might be easily regarded as 
 a distinct production, the lobes being neither bifid nor den- 
 tatcd. 
 
 C C 
 
386 DESMIUE.E. 
 
 2. MiCRASTERIAS KADIATA HaSS. 
 
 Plate XC. Fig. 2. 
 
 Char. Fi-ond orbicular, smooth. Segments hemispherical 
 each Jive-lohed. Lobes approximate, deeply bifid. Divi- 
 sions divergent, linear, and slightly bidentate. 
 
 Mici'asterias melitensis Ealfs, in Annals, vol. xiv. p. 260, 
 pi. vi. f. 2. 
 
 Hab. Amongst Diatoma fenestratum in a small pool a 
 little below the outlet of Llyn Genernon, near Dolgelly, 
 very rare : Mr. Ralfs. 
 
 Tills species is described by INIr. Ealfs under the name of 
 Micrasterias melitensis, and as the Euastrum crux melitensis 
 of Ehrenberg, which species it seems to me that it as- 
 suredly is not. In the true Micrasterias crux melitejisis the 
 frond is oval, rather than circular, and each segment is three- 
 lobed instead of five-lobed, and the lobes themselves are not 
 approximate but divergent; see PI. xc. fig. 7. The plant 
 wliich Ehrenberg figures as the young of his species seems 
 to be referrible to the following genus. 
 
 63. HOLOCYSTIS Hass. 
 
 Char. Fronds much compj-essed, formed of two deeply divided 
 segments not incised. Segments not divergent. Ij£)bes 
 angular, not radiant. Angles often spinous. 
 
 Denvation. From oKos, entire, and Kvaris, a cell ; in allu- 
 sion to the fact of the segments being entire at their 
 extremities, and not emarginate as in 3Iicrasferias. 
 
 This genus bears considerable resemblance to 3Iicrasterias 
 Ag., from which it differs mainly and essentially in the absence 
 of the radiant disposition of the lobes, which is the chief 
 character of that genus. To it should be referred perhaps 
 the Euastntm crux melitensis, pi. xii. fig. 3 c. of Ehrenberg ; 
 Arthrodesmus conoergens Ehr. approaches likewise ratlier 
 closely to the genus Holocystis. 
 
PEDIASTRUM. 387 
 
 1. HOLOCYSTIS OSCITANS Ilass. 
 
 Plate XC. Fig. 4. 
 
 Char. Frond large, smooth. Segments dilated below, con- 
 tracted above, and again dilated into a large triangular 
 lobe, ivhich is somewhat rounded on its distal side. Angles 
 spiyious. 
 
 Micrasterias ? oscitans Ralfs, MSS. ; Jenner, in Flora of 
 Tunbridge Wells. 
 
 Hab. On Ashdown Forest, near Duddleswell : Mr. 
 Jenner. 
 
 mixed up 
 with other 
 
 Jenner. 
 
 Of this species I noticed several fine specimens 
 ith other Desmidece sent me by Mr. Sidebotham. 
 
 64. PEDIASTRUM Mcyeii. 
 
 Char. Fronds coynpressed, circular, or star-like, each com- 
 posed of several cells, arraiiged in one or more united con- 
 centric circles. JSIarginal cells bipartite. 
 Micrasterias Ehrenberg. 
 Derivation. From ttsSiov, a bond ox fetter, and aarpov, a star. 
 
 The Desmidca are a beautiful tribe of productions ; and 
 none of them more so than the subjects of the present genus, 
 which cannot be confounded with any other. Distinct, how- 
 ever, as the genus Pediastrum is, considerable difficulty is ex- 
 perienced in the determination of the species, owing to there 
 being no one character which can be depended upon ab- 
 solutely in their definition ; the size of the fronds, number 
 of cells in each, and the degree of incision of the marginal 
 cells varying considerably in each : there is, however, a cer- 
 tain mean in these particulars which enables the observer to 
 determine in most cases the species or variety to which each 
 frond which presents itself to him really belongs. 
 
 ]\Icncghini has noticed the occurrrence of transparent 
 vesicles in the cells of the frond, tlie number of these varying 
 according to the species : he has therefore availed himself of 
 these vesicles in their determination, 
 c c 2 
 
388 DESMIDE^. 
 
 1. Pediastrum tetras Ralfs. 
 Plate LXXXVL Fig. 17. 
 
 Char. Fronds small, cruciform. Cells four, deeply bipartite. 
 
 Divisions, truncate, emarginate. 
 Micrasterias tetras Ehr., Infus. p. 155. t. xi. f. 1. Hete- 
 
 rocarpella tetracarpa Bory de St. Vincent, Diet. 
 
 Classique d'HIst. Nat. 1825. Heterocarpella poly- 
 
 morpJia Kiitzing, in part, Linnjea, 1833, t. xix. fig. 82. 
 
 Stauridiwn bicuspidatum, Stauridium crux melitensis 
 
 Corda, Almanac de Carlsbad, 1835, pi. iii. figs. 33, 34. 
 
 Pediastrum tetras Ealfs, in Annals, yoL xiv. p. 469. 
 
 pi. xii. fig. 4. 
 Hab. Barmouth and Penzance : Mr. Ralfs. Becklej 
 
 Furnace, near Battle, Sussex : Mr. Jenner. 
 
 A very rare and elegant species, and one of the least va- 
 riable of the genus. 
 
 2. Pediastrum simplex Hass. 
 
 Plate LXXXVL Fig. 18. 
 
 Char. Frond constituted of seven, cells disposed in a circle, con^ 
 taining 171 the centre one or two other cells tvhich are emar- 
 ginate. Divisions of the marginal cells slightly dentate. 
 
 Pediastrum hepdactis Ralfs, in loc. cit. 
 Hab. Barmouth : Mr. Ralfs. Beckley Furnace : Mr. 
 Jenner. 
 
 Distorted fronds of this species frequently occur, in which 
 the central cell is altered in form and displaced in situation. 
 See PI. Lxxxvi. fig. 18. a. Meneghini describes a single 
 hyaline vesicle in each cell. 
 
 Under the name of Micrasterias heptactis, Ehrenberg seems 
 to me to have figured two species, fig. 4. a. t. xi., being dif- 
 ferent from b, c, d, which certainly represent the present 
 plant. 
 
PEDIASTRUM. 389 
 
 3. Pediasthum elegans Hass. 
 
 Plate LXXXVL Fig. 19. 
 
 Char. Frond cii'cular, star-like, cojnjwscd of six marginal 
 cresccntic cells, and two central cells of an angular form. 
 
 Pediastrum Napoleonis Ivalfs, in Annals^ vol. xiv. p. 470. 
 
 pi. xii. fig. 6. 
 Hab. Dolgelly : Mr. Ralfs. 
 
 The above species, described and figured by ]\Ir. Ralfs 
 under the name of Pediastrum Napoleonis, and as the Micra- 
 sterias Napoleonis of Ehrenberg beai'S no resemblance what- 
 ever to the figures given of that species, nor indeed to any 
 of Ehrenbei'g's figures, save a distant one to fig. 5 e. of pi. xi., 
 which is regarded by the author as a state of Micrasterias 
 Boryanum, which it certainly cannot be, as the frond in the 
 figure alluded to is made of ten marginal cresccntic cells, and 
 fi.ve internal angular cells. 
 
 4. Pediastrum Boryanum Menegh. 
 Plate LXXXVL Fig. 13. 
 
 Char. Frond composed usually of two circles of cells, en- 
 closing a central cell, hut sometimes there are three and 
 €vcn four concentric circles, inner circle formed of Jive 
 cells, and seco7id circle of ten. ]Marginal cells deeply bifid. 
 Helierella Boryana Tm-pin, Mem. du Mus. vol. xvi. p. 319. 
 pi. xiii. fig. 22. 1828. Pediastrum simplex, P. duplex, 
 P. biscidiatum INIeyen, Nov. Act. Nat. Cur. xiv. 1829, p. 
 772, 773. t. 3. figs. 7. 13, 14. 16, 17, 18.; Isis, 1830, 
 p. 163. Opharium speciosum, O. forynosissimuyn , et O. ver- 
 ticillatnm Losano, Mem. de Zarino, xxxiii. 1829 ; Isis, 
 1832, p. 768. t. xiv. figs. 17, 18. 21. Micrasterias sim- 
 plex, M. Boryi, M. duplex, et M. Selona^a Kiitzing, Lin- 
 naja, 1833, p. 601. 3. t. xix. fig. 92 b. Euastrtnn 
 pcntangulare ct Pediastrum quadranguni Corda, Almanac 
 de Carlsbad, 1835, p. 206. 7. t. iii. figs. 32. 35. Mi- 
 ce s 
 
390 DESMIDEJi. 
 
 crasterias Boryana Ehr., Infus. p. 157. pi. f. 5. a. c. x. 
 k, h, 1, £, g, but not b, c, d, e. Micrasterias tricyclia 
 Ehr., Infus. p. 158. pi. xi. f. 8. b, c, d, f, g, e, i, but 
 not a. Pediastrum Boryanum Menegh., Synops. Desmid. 
 p. 210.; Bailey, American Bacil. fig. 20. Pediastrum 
 Boryanum Ralfs, in Annals, vol. xiv. p. 470. pi. xii. 
 fig. 7. in part 1. 
 Hob. Cheshunt, Herts : A. H. H. Brambletye, near 
 Forest Row ; Tunbridge Wells, &c. : Mr. Jenner. Dol- 
 gelley ; Barmouth ; and Penzance : Mr, Ralfs. 
 
 It appears to me that more than one species has been con- 
 founded together by different observers, and regarded as the 
 present plant. Ehrenberg has figured four species under 
 the name of Micrasterias Boryana, one of these being re- 
 ferrible to the Micrasterias tricyclia of Ehrenberg, pi. xi. 
 fig. 7. a, a plant which is British, and Mr. Ealfs, pro- 
 bably three species, the one of these- being doubtless identical 
 with Ehrenberg's Micrasterias angulosa. The Pediastrum 
 Boryanum is the commonest species of the genus. 
 
 " Sometimes plants are met with having more than three 
 circles : these are probably the Micrasterias elliptica Ehr., 
 Infus. p. 158. tab. xi. fig. 9., which Meneghini refers to 
 the present species. I am not, however, satisfied that it is 
 not distinct : the external cells agree with the description 
 given above, but the inner ones are variable in number, and 
 not arranged in regular circles. Whether it possesses any 
 other distinctive character I have not yet clearly ascertained. 
 This form is fig. 21. of the American ' Bacillaria.' " — Ralfs. 
 
 5. Pediastrum tricyclium Hass. 
 
 Plate XCII. Fig. 1. 
 
 Char. Fronds usually constituted of three circles, the inner 
 circle formed of four or Jive cells placed round a central 
 cell, the second circle of eight or ten cells, and the third 
 circle of fifteen cells. Cells someivhat quadriform, those of 
 the centre as well as the marginal ones usually incised. 
 
TEDIASTRUM. 391 
 
 M. Boryana Ehrenberg, Infus. p. 157. pi. xi. fig. 5. i, b. 
 Micrasterias tricyclia, pi. xi. fig. 8. a, but not b, c, d, 
 e, f, g, h, i, k. 
 
 Hab. In a pond in a brick-field Netting Hill : A. 11. 11. 
 
 This appears to nie to be a very distinct species. The 
 central cells arc not always placed in exact apposition with 
 each other, frequently intervals or triangular interstices are 
 left between them. Ehrenberg has strangely confounded 
 the Pediastriim Boryanum with this species, and on the other 
 hand this species with P. Boryanum. 
 
 6. PeDIASTRUM AIs'GULOSUM Ilass. 
 
 Plate LXXXVI. Fig. 14. 
 
 Char. Fronds constituted of tico concentric circles of cells 
 surrounding a single central cell, the first circle being 
 formed usually of five cells and the second of ten. INIar- 
 ginal cells alone incised. 
 
 Micrasterias aiigulosa'FAxY., Infus. p. 158. pi. xi. fig. 6. Pe- 
 diastrum Boryanum Ralfs, loc. cit. p. 470. pi. xii. fig. 7. 
 in part 1. 
 
 Hab. England. 
 
 There can be scarcely a doubt of the distinctness of tliis 
 species. It is figured by INIr. Ralfs as the Micrasterias Bory- 
 ana Ehr., with which species it has no afllinity. jSIr, Ralfs' 
 figure accords closely with Ehrenbcrg's of Pediastrum an- 
 gulosum. 
 
 7. Pediastrum constrictum Hass. 
 
 Plate LXXXVI. Figs. 15, 16. 
 
 Char. Frond large, composed of two or three concentric circles 
 of cells surrounding a single central cell, five cells in the 
 inner circle, ten in second, and fifteen in the outer circle. 
 ^Marginal cells toothed, teeth constricted. 
 
 Pediastrum Boryanum car. Ralfs, in Annals, pi. xii. fig. 8. 
 c c 4 
 
392 DESMIDE^. 
 
 This species differs so considerably in the form of the 
 marginal cells, that it is difficult to conceive it to be merely 
 a variety of that species. None of Ehrenberg's figures 
 come near to it. PI. xi. fig. 5. d. e. represent distinct species 
 of Pediastrum, which have not been described as such, and 
 the first of which might be named Pediastrum crihriforme, 
 and the second P. lunare. See Plate xcii. figs. 3, 4. Se- 
 veral other species of Pediastra are represented in Ehren- 
 berg's figures, and confounded Avith other species. These I 
 propose to figure in an appendix to this genus, in the hope 
 that they may attract the attention of those who study the 
 beautiful tribe of Desmidece. 
 
 65. SCENEDESMUS Meyen. 
 
 Char. Frond composed of from two to ten cylindrical, fusi- 
 form or oblong cells disposed in one or tivo series, outer 
 ones often lunate. 
 Derivation. From aKrjvrj, a tent, and Ssct/jlo^, a bond. 
 Arthrodesmus Ehrenberg, in part. 
 
 1. SCENEDESMUS QUADRICAUDATUS Breb. 
 
 Plate XCII. Fig. 12. 
 
 Char. Cells usually four, but sometimes there are eight in 
 each frond, rounded at the ends, disposed in a single 
 series, each extremity of the ttvo external cells prolonged 
 into a bristle. 
 
 /Q Cells rather small, external ones with a bristle at each 
 extremity, and one at the outer margin. 
 
 7 ecornis Ehr. — External cells icithout bristles. 
 
 Breb. Alg. Falaise, p. 66. Menegh. Syn. Desmid. in Liu- 
 nsea, 1840, p. 206. Arthrodesmus quadricaudatus Ehr., 
 Infus. p. 150. t. 10. fig. 16.; Pritch. Infus. p. 189.; 
 Ralfs, in Annals, vol. xv. pi. xii. fig. 4. ; Jenner, in Fl. 
 of Tunbridge Wells, p. 200. — 7 ecornis. Scenedesmus 
 
SCENEDESMU9. 393 
 
 Leihleini Kiitz., Synops. Desmid. in Linnoea, 1833, 
 p. 607. fig. 98. ; Menegh., 1. c. p. 207. Scenedcsmus 
 hijugatus, trijugatus, and minor Kiitz., 1. c. p. 607. figs. 
 97. 99. ; Jenner, 1. c. p. 200. 
 Hah. Storrington Common and Eastbourn, Sussex ; 
 Shoreham, Kent : Mr. Jenner. Chesbnnt : A. 11. H. 
 Dolgclly: Mr. Bolfs. — ^. Dolgelly : Mr. Balfs. — 
 y. Weston Bogs, near Southampton : 31?'. Jenner. 
 Bristol : Mr. Thwaitcs. Dolgelly, and Penzance : Mr. 
 Rolfs. 
 
 The cells in this species are quadrangular, alDOut three 
 times as long as broad, and rounded slightly at their ex- 
 tremities ; the external ones are usually more turgid, and the 
 bristles at their extremities are directed outwards. The 
 variety /3 and 7 are figured by Ehrenherg. 
 
 2. SCENEDESMUS DIMORPHUS Kiitz. 
 
 Plate XCII. Fig. 13. 
 
 Char. Cells fro7n four to eight in each frond, arranged in a 
 single series. Inner cells fusiform, attenuated at each 
 end ; outer externally lunate. 
 
 Achmanthis dimorjiha and bilunulata Turpin, IMcm. du 
 Mus. xvi. p. 309. pi. xiii. f. 1 1, 12, 1828. Scenedcsmus 
 pectinatus Meyen, Nov. Act. Nat. Cur. xiv. p. 375. 
 tab. 43. f. 34. 1829. Scenedcsmus bilumdatus, dimorphtts, 
 pectinatus Kiitz., Synops. Diat. Liuna3a, 1833. 608. 
 t. xix. fig, 93. ; Ehr. Die Infus. p. 150. tab. x. fig. 17. ; 
 Ealfs, in Annals, p. 403. pi. xii. fig. 5. 
 
 Ilah. Dolgelly : Mr. Ealfs. Near Bristol : Mr. Thwaitcs. 
 
 This is a very distinct and pretty species. 
 
 3. SCENEDESMUS ACUTUS MegeU. 
 
 Plate XCII. Fig. 14. 
 Char. " Cells two to six, fusiform, acute at both ends, un- 
 
394 DESMlDEiE. 
 
 equally ventricose, arranged in a double, irregularly alter- 
 nating series.^' 
 
 Arthrodesmus acutus Elir., Infus. p. 150. tab. 10. fig. 19. 
 c, d ; Meneg. 1. c. p, 207. ; Kiitz. 1. c. p. 609. fig. 96. ; 
 Ralfs, in Annals, vol. xv. p. 403. pi. xii. fig. 6. 
 
 "I notice this species because the Rev. M. J. Berkeley 
 has gathered it near King's Cliff, and I have occasionally- 
 met with specimens which agree with Elirenberg's figures ; 
 but as I omitted to draw up a description at the time, I have 
 borrowed the specific character from Meneghini." — Ralfs. 
 
 4. SCENEDESMUS OBTUSUS Mcnegk, 
 
 Plate XCII. Fig. 15. 
 
 Char, Cells three to eight, ovate or oblong, xcitli rounded ends, 
 and arranged alternately in two rows. 
 
 Menegh. I. c. p. 208. Sceiiedesmus quadraltermis Kiitz., 
 1. c. p. 608. fig. 94. Scenedesmus octalternxis Kiitz., 
 1. c. p. 609. fig. ^6. Arthrodesmus acutus Bailey, 
 Amer. Eacil. fig. 18 ? ; Ralfs, in Annals, vol. xv. p. 404. 
 fig. 8. 
 
 Hah, In boggy pools, Dolgelly : Ralfs. 
 
 " The specimens I have examined did not agree in every 
 respect with the description and figures of this species, but 
 they probably belonged to it. The cells were ovate, the 
 broad ends of the rows placed alternately, the smaller ends 
 being in different directions ; sometimes the cells seemed only 
 held together by the hyaline matrix, in which state they 
 appear to connect the Desmidea, through Gonidium Ehr. 
 and TrocAwcm Kiitz., with \kv^ Ulvacea. The cells of one 
 row are separated by the interposition of the broader ends of 
 the other."— iJflZ/^. 
 
 Note. Several of the figures of this family, especially certain of those 
 of the genera Euastrum and Cosmarhan, are taken from those of Jenner 
 and Ralfs, Ulustraling the series of papers on the Dcsmidece inserted in 
 the " Annals." 
 
395 
 
 ALGM SILICAT/E. 
 
 Fam. XX. DIATOMACEJE. 
 
 Char. Algge silicious. 
 
 The DiatomacecB form a group of natural productions not 
 less distinct and remarkable than the previous one of Dcsmi- 
 decB, Avith which it may be contrasted. 
 
 The Dcsmidece. are Alga of figured and peculiar forms, 
 binary composition, vivid green colour, destitute of silex in 
 their constitution, and therefore subject to considerable change 
 of form in di'ying. 
 
 The DiatomacecB are productions possessing also, to a cer- 
 tain extent, figured forms, but are not binary, of excessive 
 fragility, of a dark brown colour, Avhich changes somewhat to 
 green on drying, of a metallic lustre and silicious composi- 
 tion, and therefore unalterable in diying, and indestructible 
 by fire. 
 
 The silex which enters so abundantly into the composition 
 of these plants is disposed throughout the interior of the 
 frustules in plates, which are often arranged in series, which 
 when the frustules are examined microscopically, are seen to 
 impart certain lines or mai'kings to them, which contribute 
 much to their beauty, and which are of importance in the 
 discrimination of genera and species. 
 
 It is thus seen how very little connection tliis group and 
 family of productions has with the undoubted xUga which 
 have hitherto been described ; indeed, the claims which they 
 possess to be regarded as subjects of the vegetable kingdom 
 arc by no means so conclusive as those which have been 
 advanced in favour of the vegctability of the Dcsmidca. 
 
396 DIATOMACE^. 
 
 But the evidence of which we are in possession would appear 
 greatly to preponderate in proof of the vegetable character 
 of the DiatomacecB ; thus, putting aside their silicious consti- 
 tution, and the partitions in the cells : the filaments of the 
 MeloseircB do not differ in the least in their modes of developc- 
 ment and growth from those of the VesiculifercB, nor indeed 
 do those of Fragilaria differ very essentially from the fila- 
 ments of the true AlgcB ; in their reproduction, likewise, so 
 far as this has been ascertained, the Diatomaceoe correspond 
 with the DesmidecB, and perhaps with all the lower Algce. 
 
 In support of their animal nature may be urged their 
 colour, which is different from that of all other undoubted 
 vegetable productions, and the silex of which they are prin- 
 cipally constituted. These arguments, however, are not con- 
 clusive, nor are they of as much weight as those adduced in 
 proof of their vegetability. It is probable that in this matter, 
 as in many otlier disputed points, the truth lies in the mean, 
 and that the DiatomacecB are neither exclusively animal, nor 
 exclusively vegetable, but of a nature intermediate. 
 
 Owing to the presence of silex, the most indestructible 
 of substances, the species of this family are frequently found 
 beautifully preserved in a fossil state, and often in amazing 
 quantities all over the world. In the arts, the powder which 
 they form has been employed for polishing. Many of the 
 fossil species are identical with those now found in a recent 
 state. 
 
 Section i. 
 ^vo\\^Jilamentous. 
 
 A. Filaments cylindrical. 
 
 66. MELOSEIRA Ag. 
 
 Char, Filaments cylindrical, subulate. Cells divided in the 
 centre or hilocular, sometimes vesicular. Junction sur- 
 faces of the cells either rounded or truncate, plain or 
 striated. 
 
MELOSEIRA. 397 
 
 Derivation. From fjbsXos, a membej', and asipa, a chain. 
 
 The species of the genus Meloseira admit of division into 
 two subgenera. Tlie first of tlicse, tlvc species of which are 
 chiefiy marine, and to designate which the word Sphcerophora * 
 might be employed, are cliaracterized by a pccuhar form and 
 structure of the cells. The extremities of these are rounded, 
 and each contains, at first, one, and afterwards tAvo spherical 
 vesicles or globules, divided by strongly marked double lines. 
 In consequence of there being no distinct articulating sur- 
 faces, the filaments are excessively fragile, so that it is rare 
 to find one of any length. 
 
 In the second subgenus, with which we have chiefly to do, 
 and the species composing which are, for the most part, in- 
 habitants of freshwater, tlie cells are truncate at their ex- 
 tremities, so that their articulating surfaces are directly applied 
 to each other, and slmjjly bilocular, and not globuliferous. 
 This subgenus admits also of further division, according as 
 the articulating surfaces of the cells are either plain or ser- 
 rated, and striated. 
 
 The genus Meloseii-a, amongst the Diatomacea;, seems to 
 have been constituted with a view of making apparent the 
 aflSnity which undoubtedly exists between the DiatomaceoB 
 and the AlgcB proper, not merely in form and developcment 
 approximating so closely to the genus Vesiciilifera amongst 
 the true ConfervcB, but also in a measure in its i-eproduction. 
 As in VesicuUfcra, at a certain period, particular cells lose 
 their cylindrical form, and become globular or vesicular, and 
 contain endochrome : here, however, the analogy would ap- 
 pear to cease ; for this endochrome, so far as my observation 
 goes, never becomes condensed into a distinct organ or spo- 
 rangium similar to that with which we are familiar in the 
 families ConjugatecR and Dcsmidccs. Notwithstanding this 
 striking resemblance to a genus of the Co7\ferv(B, the Melo^ 
 seircs are true members of the family of Diatomacea, as is 
 clearly indicated by their silicious natm-c, and consequent 
 striated structure. 
 
 * Derivation. From ailutipcr, a globule, aiul (l>o(>uo, to bear. 
 
398 DIAT0MACEJ3. 
 
 The species are all included by Ehrenberg in his genus 
 Gallionella. 
 
 a. Filaments not globuliferous. 
 
 * Extremities of the cells serrated at the edges. 
 
 1. Meloseiea aeenosa Moore, MS. 
 
 Plate XCIII. Figs. 2, 3. 
 
 Char. Filaments large, dark brown. Frustules * ticice or even 
 three times broader than long, divided in the centre by a 
 double line. 
 Gallionella varians Ehr., Die Infus. p. 167. t. 21. fig. 2. 
 3Ieloseira arenosa Moore, MS. M. arenaria Ealfs, 
 in Annals, vol. xii. p. 349. pi. ix. fig. 4. 
 Hab. On a Avet bank near Larne, co. Antrim : Mr. Moore. 
 Inner extremity of the Giant's Causeway: Mr. W. 
 Thompson. Very sparingly in a stream near Shoreham, 
 Kent : Mr. Jenner. 
 
 This is by far the finest species of the genus, and is evi- 
 dently the plant which Ehrenberg had in view as the Melo- 
 seira varians of Agardh, his description of that plant being as 
 follows : — 
 
 " Corpusculis utrinque planis, cylindricis aut nummifor- 
 mibus, a dorso glabris, a latere radiatim striolatis, ovariis 
 flavis aut flavo-viridibus." 
 
 It is probable, as Ehrenberg has correctly figured both 
 species, that he regarded the true Mcloseira varians of Agardh 
 as the young state of his species. 
 
 The end surfaces of the frustules are closely applied to each 
 other, faintly marked with radiating strise with their margins 
 serrated, the teeth of one frustule locking into those of the 
 other with which it is in contact, in the same manner as the 
 teeth of certain wheels are made to fit each other. 
 
 The name should be arenosa, and not arenaria. 
 
 * The term frustule, applied to the Diatomacece, has the same meaning 
 as the -word cell used to describe the ConfervcB. 
 
MELOSEIRA. 399 
 
 2. Meloseira orichalcea Kutz. 
 Plate XCIII. Figs. 6, 7. 
 
 Char. Filaments rather slender^ tohen recent of a fawn colour. 
 
 Frustulcs two or three times longer than broad, twice 
 
 divided near the centre. 
 Klitzing, in Linna3a, 1833, ]}. 71. fig. 68. Gallionella auri- 
 
 chalcea Ehr., Die Infus. p. 168. t. 10. fig. 6. ; Amer. 
 
 Bacil. part 2. p. 5. pi. xi. fig. 4 b. 
 Hah. In ditches and slow streams, Chcsliunt : A. H. H. 
 
 Stevenston, Ayrshire : Rev. D. Landsborongh. Dol- 
 
 gelly : Mr. Ralfs. 
 
 This species differs from Meloseira varians., with Avhich it 
 might be confounded, in its smaller filaments, different colour, 
 longer fnistules, in the double division of these, and especially 
 in the dentated margins, by which M. orichalcea is related to 
 Meloseira arenosa, and which is the only character in common 
 between the two species. The Galliondla disians of Ehr, 
 comes close to this species, if it be not identical with it. 
 
 ** Margins of the cells smooth. 
 
 3. Meloseira varians Ag. 
 
 Plate XCIII. Figs. 4, 5. 
 
 Char. Filaments rather thick, dark brown, becoming greenish 
 in drying. Frustules once or once and a half as long as 
 broad, once divided in the centre. 
 Ag. Conspect. Diatom, p. 64. ? Kiitz. in Linnsea, p. 71. 
 fig. 69. ; Harv. Br. Alg. p. 195. M. lineata Ag., Syst. 
 p. 8. ; Harv. in INIanual, p. 1 95. Gallionella varians 
 ■ Ehr., Die Infus. t. 10. fig. 4. G. aurichcdcea Bailey, 
 Amer. Bacil. part 2. pi. 2. fig. 4 c. Conf. lineata Dillw., 
 p. 44. t. yS Jurg, Dec. 5. No. 18. Conf. hyemalis Jurg, 
 Dec. No. 17. No. 6. Vesiculifera comjmsita Ilassall, in 
 Annals of Nat. Ilist. vol. x. p. 394. ; Ralfs, in Annals, 
 vol. xii. p. 350. pi. ix. fig. 5. 
 
400 DIATOMACE^. 
 
 Hab. Everywhere common in ditches and rivulets. 
 
 " In a stream below Penmaen Pool, near Dolgelly ; and 
 within the influence of the tides, I have gathered a tufted 
 state of this species of a bluish colour, not unlike the iridescent 
 tints of Cystoseira ericoides. It was growing with Ectocarpus 
 littoj^alis. I have also for several years observed it in the 
 same state in a cave by the sea side at Penzance ; in both 
 instances it afterwards became brownish, and finally green." 
 — Balfs. 
 
 It is on this species that the inflated vesicles usually occur, 
 and which formerly induced me to refer it to a section of the 
 genus Vesiculifercu 
 
 4. Meloseira ochracea RaJfs. 
 
 Char. " Frustules very slender, convex at each end, ovate, not 
 striated, ferruginous. Filaments often connected toe/ether 
 in a suhrajnose manner.''^ 
 
 Gallionella ferruginea Ehr., Die Infus. p. 169. t. 10. fig. 8., 
 and t. 21. fig. 3. Conf. ochracea Dillw., t. 62. Oscil- 
 latoria ochracea Grev., Flor. Edin. p. 304. ; Harv. Br. 
 Alg. p. 167. M. ochracea Kalfs, in Annals, vol. xii. 
 p. 35. 
 
 Hab. Pools and slow streams in boggy soils. 
 
 " This plant occurs in delicate ochraceous or ferruginous 
 masses, falling into powder on the slightest touch. The fila- 
 ments are so slender, and the joints so obscure, that I have 
 been unable to determine the form of the frustules, and have 
 therefore taken the specific character from Ehrenberg : I am 
 also unable to ascertain whether the joints are marked by any 
 central line. Plaving received from Mr. Dillwyn a specimen 
 of his Conf. ochracea, which I am able confidently to refer to 
 this species, I have restored the original specific name. 
 Ehrenberg is no doubt correct in placing the plant in this 
 genus, as the filaments are cylindrical and silicious. 
 
 " When submitted to a red heat it acquires a reddish tinge, 
 
ACHNANTHES. 401 
 
 wliich circumstance, together with the colour and slender fila- 
 ments, will distinguish it from all other species." — Ralfs. 
 
 67. ACHNANTHES Bory. 
 
 Char. Frond stipitate, sta7idard-shaped, composed of few 
 frustules, 2c]iich are longer than broad, curved, and have a 
 punctum at the centre of the inferior margin. 
 Derivation. From a.%1^77, the froth of the ocean, and avOos, 
 a flower. 
 
 The stipes is attached not to the centre of the lower frus- 
 tule but to one of its angles, and this position of It gives rise 
 to the resemblance of each entire frond to a standard. 
 
 1. ACHNANTHES MINUTISSIMA Kutz. 
 
 Plate C. Fig. 4. 
 
 Char. Frustules small, slender ; in lateral view obtuse, and 
 apparently without stria. Stipes very short. 
 
 Kiitz. Syn. Diatom, p. 578. f. 54. ; Ehr. Infus. p. 228. 
 pi. XX. f. 5. ; Ralfs, In Annals, vol xlii. p. 492. pi. xiv. 
 fig. 2. ; Jenner, In Flor. of Tunbridge Wells, p. 200. 
 
 Hab. Parasitic on other AlgcB, Newtimber, Sussex : Mr. 
 Borrer. Several places in Sussex, &c. : Mr. Jenner. 
 Cheshunt : A. H. H. Oswestry : Rev. T. Salwey. Pen- 
 zance : Mr. Ralfs. Bristol : Mr. Thicaifes. 
 
 The fronds are very minute, and rarely consist of more than 
 two frustules. 
 
 " Before I had the opportunity through ISIr. Borrer's kind- 
 ness of comparing our plant with the specimen in Kiitzing's 
 ' Alg. Aq. Dulc' I considered It a variety of the following 
 species; and I am still uncertain whether they should be 
 separated, although the plant above described Is undoubtedly 
 Kiitzing's Achnanthes minutissima.'" — Ralfs. 
 
 D D 
 
402 DIATOMACE^. 
 
 2. ACHNANTHES EXILIS ? KtltZ. 
 
 Plate C. Fig. 5. 
 
 Char. Frustules slender^ from one to nine in each jrond. 
 
 Lateral surfaces subacute. Striae indistinct or wanting. 
 
 Stipes longer than the frustule. 
 Klitz. Syn. Diatom, p. 578. f. 53. ; Ehr. Infus. p. 228. 
 
 pi. XX f. 5. ; Ralfs, in Annals, vol. xiii. pi. xiv. fig. 12. 
 Hah. Parasitic on Gomphonema geminatum in several 
 
 streams, near Dolgelly : 3Ir. Ralfs. 
 
 From Achnanthes minutissima this species differs in its 
 elongated stipes, greater number of frustules in each frond, 
 and in its more acute lateral surfaces. 
 
 Although I have compared our plant with Kutzing's 
 Achnanthes exilis I am not certain that it is the same species. 
 It agrees with Kutzing's specimen in its crowded habit and 
 elongated stipes, but its frustules are much smaller, and 
 its lateral surfaces less acute, in both which respects it is inter- 
 mediate between Ach. mi7mtissima and Kutzing's specimen of 
 Ach. exilis, 
 
 B. Filaments compressed. 
 A. Frustules in front view quadrangular^ 
 
 68. TETRACYCLVS Ralfs. 
 
 Char. Frustules coherijig so as to form a fragile, attenuated 
 filament, never united by their angles, striated strongly 
 laterally ; foui-- sided, each side rounded, and forming the 
 segment of a distinct circle. 
 
 Derivation. From rsrpas, four, and kvkXos, a circle. 
 
 This genus differs only from Tessella and Striatella in the 
 frustules not cohering by the angles. 
 
TETRACYCLUS. 403 
 
 1. Tetkacyclus LACUSTRIS Ralfs. 
 Plate XCIII. Figs. 8, 9. 
 
 Char. Frustulcs about twice as long us broad. Lateral sur- 
 faces tcith from seven to nine distinct transverse stria ; in 
 end y'xQM four-lobed. 
 Hob. Llyn Prcfeddyr, near Barmouth : Rev. T. Salwey. 
 Pools near Dolgelly : Mr. Ralfs. 
 
 In consequence of the four-lolled form of the frustulcs 
 composhig a filament, and which arises from the inflation of 
 the central part of each frustule, it happens that when ex- 
 amined l)y the microscope that the centre of one side or lobe 
 is seen together Avith a portion of two other lobes, one on each 
 side, the boundaries of the lobe in view being indicated by two 
 lines running down the length of the filament. But as the 
 lobes are not all of equal size, those only being so which are 
 opposite to each other in the filament, it follows that the 
 quantity of the other two lobes seen varies according to the 
 side of the filament which is uppermost. Noav, the longer sides 
 or lobes are those which form the margins of the filaments, and 
 those which form the centre the shorter, the filament rests of 
 course usually upon one of the shorter lobes : from this it re- 
 sults that in the filaments in their usual position, that a con- 
 siderable portion of the lateral lobes is seen, but in the cases in 
 which they rest upon their longer or marginal lobes a very 
 small portion only of the lateral lobes is in view. The smaller 
 and shorter lobes correspond to the back and front of the fila- 
 ment, and the larger and longer to the margins, which may be 
 distinguished in addition to their breadth by the presence of 
 stria?, more strongly marked than they are in the centre of 
 the filament : the terminations of the fi'ustules in this view 
 are also punctated, although not contracted. In the marginal 
 view, that is with the margin of the filament uppermost, but 
 a very slight portion of the back and front lobes is seen, the 
 striffi are°most strongly marked in the centre, and describe 
 quadransidar spaces, the frustulcs are contracted also at their 
 points of junction where they present no puncta. 
 
 D D 2 
 
404 DIATOMACE^. 
 
 In the end view the frustules have been aptly compared to 
 the quatrefoil of a gothic window : in the smaller filaments in 
 this aspect, they are about as long as broad, in the larger one 
 and a half times as broad as long ; and each has about seven 
 Avell-marked stria?, a central straight stria which extends from 
 one marginal lobe to the other, and three curved stria? be- 
 longing to each of the front and back lobes. 
 
 69. TABELLAEIA S/iuf. 
 
 Char. Frustules quadrangular, fusiform, cohering hy their 
 angles, traversed in the centre by a longitudinal canal, 
 marked icitli transverse * stria, interrupted in the centre by 
 the canal. End view destitute of markings. 
 Derivation. From tabella, a letter ; which the frustules re- 
 semble in form. 
 
 The term Bacillaria is applied by Ehrenberg to the spe- 
 cies of this and the following genus, as well as to a curious 
 production wholly different from either genus, the Bacillaria 
 paradoxa, and to which species I jjropose that the genus 
 Bacillaria should now be confined. By Agardh, the ap- 
 pellation of Diatoma is given to them. ]Mr. Shuttleworth 
 has proposed the division of the genus Diatoma into two 
 genera, in the propriety of which I fully concur ; for one of 
 these Mr. Shuttleworth reserves the name of Diatoma, that 
 of the other is derived from a species named by Ehrenberg 
 Bacillaria tabellaris, and which species is typical of the genus. 
 
 1. Tabellaeia flocculosa. 
 
 Plate XCIV. Figs. 9, 10.; Plate XCVI. Fig. II. 
 
 Char. Frustules in young spscimens as long as broad, in older 
 sjiecimens their breadth exceeds their length by two or three 
 times. Stria? from one to scvcji on each side. In end 
 
 * The word transverse has here a meaning dlflferent to that generally 
 assigned to it ; it here has reference to the width of the cell or filament, 
 and not to its depth. 
 
TABKLLARIA. 405 
 
 view frustules dilated in the centre hy the canal, with 
 rounded extremities. 
 Diatoma jioccnlosum Ag., Syst. p. 4. ; Kiitz. in Linnaja, 
 1833, p. 584. 1. 17. f.67. ; Hook. Br. Fl. vol. vii. p. 406.; 
 Harv. Br. Alg. p. 202. Conf. focculosa Dilhv., Conf. 
 t. 28. ; Eng. Bot. t. 1761. Dacillaria tahcllaris Elir., 
 Infus. p. 199. jil. XV. f. 7. Diatoma focculosn)n liar's, 
 in Annals, vol. ix. pi. ix. fig. 3. Bacillaria Jlocculosa 
 Ehr., Infus. t. xv. f. 9. B. seriuta Ehr., Infus. t. xv. 
 fig. 8. 
 Hah. Common in pools, &c. 
 
 This is a very variable species, and it is not to be wondered 
 at that a difference of opinion should have existed as to 
 whether the conditions of it represented in " Eng. Bot." and 
 in Dillwyu's " Confervas " were not in reality distinct species. 
 Tliat they are not so, however, is certain, as well as that both 
 are difl'erent stages of the growth of the same production. 
 In the young state, the cells arc as long and even longer than 
 broad, each side of the frustule being marked with often as 
 many as seven well-marked stria3 ; and the central canal is 
 large and circular. From this state intermediate specimens 
 are often met Avith, some having the frustules once and a half, 
 others twice, and others thrice, and even many times as broad 
 as long. Corresponding with this gradual lateral enlargement 
 of the frustules, we find the number of the striaj to dimini.<h 
 gradually, until at last but one or two exist on each frustule, 
 and at the same time, a gradual diminution in the size of the 
 central canal occurs, until at length this is nearly obliterated. 
 Thus the ultimate stage of the species bears some resemblance 
 to Tahellaria fcncstrata, and is the Bacillaria scriata of 
 Ehrcnbcrg. For these changes see the figures. 
 
 2. Tabellakia fenestkata. 
 
 Plate XCVI. Fig. 10. 
 
 Char. Frustules four or Jive times longer than broad; in end 
 
 view subinjiated in the centre icith iiicrassated ends. 
 
 D n 3 
 
406 DIATOMACE^. 
 
 Diatoma fenestratum Lyngb., Hydr. Dan. t. 61. E. 3. ; 
 Ag. Consp. Diatom, p. 53. ; Hook. Br. Fl. vol. vii. 
 p. 406. ; Harv. Br. Alg. p. 202. ; Kalfs, in Annals, 
 vol. xi. p. 453. pi. ix. fig. 4. ; Jenner, in Flora of Tun- 
 bridge Wells, p. 200. 
 
 Hab. Pools, &c. ; Sussex, &c. : Mr. Jenner. Cheshunt : 
 A. H. H. Barmouth, North Wales : Rev. T. Salwey. 
 Dolgelly, and near Pont-Aberghas-lyn, North Wales, 
 and Penzance : BIr. Rolfs. Stevenston, Ayrshire : Rev. 
 D. Landshorough. Aberdeen ; Dr. Dickie. 
 
 This is one of the least variable of the species of this and 
 the following genus ; it may however be confounded with 
 TabeUaria Jiocculosa in the last stage of its developement ; 
 but with a little care it may be readily distinguished there- 
 from. In T. fenestrata the frustules are connected by a per- 
 ceptible hinge, and on each fully developed frustule there are 
 at each extremity two stria?. In T. Jiocculosa tbe mucous 
 hinge is not visible connecting the frustules, which are usually 
 much longer, and on the narrowest, Avliich approach nearest to 
 T. fenestrata, there is frequently but a single stria at one 
 side, and two at the other. The end views of the frustules 
 in the two also differ. In T. Jiocculosa the frustule is more 
 slender, the ends less incrassated, and the canal more pro- 
 longed. 
 
 The frustules in this species and in D. elongatum are often 
 curiously thrown back so as to form two lengthened scries. 
 
 70. DIATOMA Ag. 
 
 Char. Frustules not having a central canal or lateral stricB, 
 punctated at the sides, the puncta being produced by the 
 presence of grooves, which pass round the frustules. Junc- 
 tion surfaces often striated. 
 
 Derivation. From hiaroixri, ijicision ; the plant looking like 
 a band cut into portions, which cohere only at the 
 angles. 
 
BIATOMA. 407 
 
 1. DiATOMA VULGAKE BoriJ. 
 
 Plate XCIV. Figs. 1, 2. 
 
 Char. Frustules tico or three times broader than long, some- 
 times attached by a stipes. Lateral puncta very evident. 
 End view inflated, incrassatcd at the terminations, and 
 striated. 
 
 Diatoma vulgare Kutzing, In Llnnrea, 1833, p. 582. f. 66. 
 D. tcnue Grcv., Crypt. Fl. t. 354. ; Berk. Brit. Alg. 
 t, 6. ? Hook. Br. Fl. vii. p. 406. ; Harv. Manual of Br. 
 Alga3, p. 202. D. tenue a moniliforme (Young) Kiitz., 
 in Linna^a, 1833, p. 580. f. 60.? D. tenue /3 interme- 
 dium Kiitz., 1. c. p. 580. f. 61.? D. flocculosum Ag., 
 Consp. Crit. Diatom, p. 53. excl. syn. Dilhv. Bacil- 
 laria vulgaris Ehr., Die Infus. p. 197. pi. 15. f. 2. 
 Diatoma vulgare Ralfs, in Annals, vol. xi. p. 450. pi. viii. 
 fig. 8. ; Jenncr, in Fl. of Tunbridgc Wells, p. 202. 
 
 Hah. Pools, streams, &c. King's Cliff, Northampton- 
 shire : Rev. 31. J. Berkeley. Heufield, Sussex : 3Ir. 
 Borrer. Shoreham, Kent, and several stations about 
 Lewes and Tunbriclge Wells : Mr. Jenner. ShreAVsbury : 
 Mr. Leighton. Oswestry, Shropshire : Rev. T. Sahoey. 
 Cheshunt, Herts : A. H. H. Ireland ; Mr. D. Moore. 
 
 This species, like most of the Diatomacece, varies very con- 
 siderably in the length and breadth of the frustulc, as well as 
 in the degree of its convexity. Usually each frustule is about 
 two and a half times as broad as long ; in this state the frus- 
 tules are seen to be very convex in the end view, but some- 
 times older specimens are met with, in which the breadth of 
 the frustules exceeds some five or six times their length, and 
 in this they are scarcely at all convex when viewed endways. 
 This condition of the species might almost mislead one to re- 
 gard it as a distinct species. See the figures. 
 
 From Diatoma tenue, or rather D. clongatum, of which 
 D. tenue is but a state, with which, however, there is but 
 little danger of confounding it, D. vidgare may be distin- 
 guished by the greater breadth of the frustules, their con- 
 
 D D 4 
 
408 DIATOMACE^. 
 
 vexity in the end view, and the different character of the 
 marginal strite. Owing to the frustules being convex, not 
 merely in thickness, but having rounded extremities, the 
 stride are evident on a portion of the front surface. 
 
 The species grows most luxuriantly in gently running 
 water, frequently investing Cladophora glomeraia, and causing 
 it to appear of a deep brown or chocolate colour. It is at- 
 tached to this plant by means of a stipes, first detected by 
 Mr. Jenner, the existence of which from its locality in flow- 
 ing water might have been predicted. 
 
 In drying it changes to a greenish hue. 
 
 2. DiATOMA ELONGATUM Ag. 
 
 Plate XCIV. Figs. 3, 4, 5, 6. 
 
 Cliar. Frustules 77umy times as hroad as long, at first ivith 
 straight margins, suhsequentlg, xolien fully developed, the 
 sides are dilated on the front surface. End view linear, 
 with slightly incrassated ends. — /3 cuneatum. Frustules 
 iDedge-shaped. 
 
 Diatoma tenue Ag., Consp. Diatom, p. 52. D, tenue B 
 7iormale Kiitz., in Linnfea, 1838, p. 580. t. 17. f. 63. D. 
 eloJigatumBevk., Glean, t. 6.; Hook. Br. Fl. 406.; Harv. 
 Manual, p. 202. D. sulphurascens Ag., Consp. Diatom, 
 p. 53. Co7if. focculosa Dillw., Br. Conf t. 28. f. c. ? 
 Bacillaria pectinaUs Ehr., Infus. p. 198. pi. xv. fig. 4. in 
 part only. Z>. elongatiim Ag., Syst. p. 4. ; Kiitz. in Lin- 
 na?a, p. 582. t. 17. f. &5. Bacillaria elongata Ehr., In- 
 fus. p. 218. f. 169. D. tenue and D. elongatum Ealfs, 
 in Annals, vol. xi. p. 451, 452. pi. ix. fig. 1. ; Z>. tenue 
 Jenner, loc. cit. p. 202. Bacillaria cuneata Ehr., Infus. 
 t. XV. fig. 6. Diatoma tenue <y cuneatum Kiitz., in Lin- 
 nffia, 1833, p. 580. t. 17. fig. 62. 
 
 Hab. Pools and streams. Near Tunbridge Wells : 3Ir. 
 Jenner. Shrewsbury: Mr.Leighton. Cheshunt: ^. i/. iZ 
 Bangor, and Dolgelly, North Wales ; Penzance : Mr. 
 
DIATOMA. 409 
 
 Ralfs. Aberdeen : Dr. Dickie. Stevenston, Ayrshire : 
 Rev. D, Landsborough. 
 
 This is a very variable species. In the young state the 
 frustules are plain, but in their fully developed condition 
 they are dilated laterally, or as most writers would say, at 
 each extremity. These two states have been separately de- 
 scribed as distinct species, but I have no hesitation in uniting 
 them. I have preserved the specific appellation of elongu' 
 turn in preference to that of tenue, because the latter term was 
 applied by Ehrenberg to the condition of the species with 
 dilated frustules, in fact to the species in its fully developed 
 or perfect state. 
 
 The younger frustules in the end view are slightly dilated 
 in the centre with incrassated ends ; in this state they bear a 
 slight resemblance to the older ones of Diatoma vulgare, but 
 are much smaller. The fully developed frustules in the end 
 view are linear and very slightly incrassated. 
 
 Remarkable as the variety with cuneate frustules is, it is 
 I suspect but an anomalous condition of the species. 
 
 Light brown or yellow when recent, assuming a faint 
 green tinge in drying. 
 
 3. DiATOaiA VIRESCENS Hciss. 
 
 Plate XCV. Figs. 7, 8. 
 
 Char, Frustules usually hco or three times hroader than long, 
 frequently cohering together in the manner of a Fragi- 
 laria. In end view oval, icith slightly constricted extre- 
 mities. Striai inconspicuous. 
 Fragilaria pectirialis ISihr., Die Infiis. p. 206. t. 16. f. 1. 
 excel, a; Pritch. Infus. p. 222. fig. 176. Fragilaria 
 virescens Ralfs, in 1. c. p. 110. \}\. 11. fig. 6. ; Jenner, 
 1. c. p. 202. 
 Hah. Cold bath spring, Broadwater Forest ; Lower 
 Green ; Rotherfield and Piltdown Common : Mr. Jen- 
 ner, Madron and Chyanhal ]\Ioor, near Penzance : 
 
410 DIATOMACE^. 
 
 Mr. Ralfs. Pond near Wormley, AVest End, Herts : 
 A. H. H. 
 
 The greatest peculiarity of this species is, that frequently 
 the frustules cohere together in considerable numbers, so as 
 to form filaments apparently similar to those of Fragilaria^ 
 but in all probability really distinct. If, however, the speci- 
 mens be dried or kept in water, these filaments will generally 
 be found broken up in the manner of a Diatoma. 
 
 The only species with which it needs to be contrasted is 
 Diatoma vulgaris, from which it may be distinguished by the 
 absence, or at all events the exceeding fineness of the stria?, 
 on the end surfaces of the frustule, as well as by the fila- 
 ments, which It usually forms. 
 
 The colour is stated to be green, not altering nuich in dry- 
 ing. In my specimens it has been dark brown, changing to 
 a greenish hue in the herbarium. 
 
 The removal of this species from Fragilaria to Diatoma 
 will render that o-enus a natural and not an anomalous one. 
 
 71. BACILLARIA Gmelin. 
 
 Char. Frustules sliding one upon the other. 
 
 Derivation. From hacillum, a small stick. 
 
 In the genus Bacillaria Ehrenberg includes not merely 
 the species of the two preceding genera, but likewise the sin- 
 gular production which forms the type of the limited genus 
 Bacillaria. 
 
 1. Bacillaria paradoxa Gmelin. 
 
 Plate XCIIl. Fig. 10. 
 
 Char. Frustules very many times broader than long, cohering 
 together in considerable numbers upon the same plane, 
 motive upon each other. In end view striated. 
 F. sonderbares Stabgenthier Miiller, Muller's Kleine 
 
I3ACILLARIA. 411 
 
 Schriften v. Goze, p. 1. fab. 1. 8., 1782; Pinddyr Nye 
 Samling af Dansk Vidensk. Sallsk. Skrift. 11. p. 277. 
 Vibrio paxilUfer JNIiiller, Aniraalc. Infus. p. 54. t. 7. 
 f. 3. 7., 1786. Bacillaria jmradoxa Gmclin, Linnaei 
 Syst. Nat. ed. xiii, vol. vi. 1788. Vibrio loaxillifer La- 
 mark, Systeme dcs Anim. sans Vert. 1815. Bacillaria 
 palea Nitzsch, in part, Beitrage zur Infusorienkuude, 
 1817; Eucyclopadie v. Ersch u. Grubcr, 1821. Bacil- 
 laria paradoxa Bory de Saint Vincent, Diet. Classique, 
 1822. B. 3IiUleri Bory, Encyc. Meth. 1824. Oscil- 
 laria paxiUifera Sclu'auk, Nov. Act. Nat. Cur. xi. 2. 
 p. 534. 539. Bacillaria Mulleri Tnrpin, Diet, des Sc. 
 Natm*. Vegetaux Acotylcdones, 1828. Bacillaria para- 
 doxa, Abhandl. dcr Akadeinie d. Wissenseb. zu Berlin, 
 1831, p. 83. ; 1833, p. 319. ; Ehr. Infus. p. 196. t. xv. 
 f. 1. 
 
 This is the most singular of all the Diatomacccc, and i\\Q 
 most protean in the forms which it assumes ; the variety of 
 which results from the power which the frustulcs undoul^t- 
 edly possess of gliding one upon the other. Sometimes 
 the margins of the frustules correspond in position with 
 each other, and then an elongated lamina is formed similar 
 to that of the Fragilarim. At others the frustules are drawn 
 out from each other by two and three together, and the 
 margins are rendered uneven ; iand again at others, each frus- 
 tule composing a frond is drawn out, so that it adheres but 
 by a very small portion of its length to the frustule or frus- 
 tules, one on each side, with which it is connected. Now 
 this disposition of the frustulcs could only be effected by the 
 possession of a power of motion the one upon the other. 
 
 Ehrenberg in his definition of this species makes use of 
 the following phrase, " baccillis singuhs alacriter mobilibus ; " 
 and, again, in the definition given in French, " les baguettes 
 vivemcnt mobiles." Now it ought not, I apprehend, to be 
 imagined, as the words quoted would lead us to suppose, that 
 the frustules possess each and individually a power of loco- 
 motion centered in themselves, but merely that they are so 
 
412 DIATOM ACEiE. 
 
 loosely aggregated together as that a slight force should 
 occasion a lateral displacement of them. Still it must be 
 allowed to be very singular, that the frustules should not 
 rather separate altogether from each other, than allow so 
 great a displacement as is frequently seen to occur, and yet 
 should retain their adherence. 
 
 A separate frustule bears much resemblance to the un- 
 dilated form of the frustule of Diatoma elongatum. Colour 
 yellowish brown. 
 
 I am in some doubt as to the precise locality of this pro- 
 duction. It was either gathered by the Rev. D. Lands- 
 borough at Stevenston, in Ayrshire, and then probably found 
 near the sea, or (what is less likely) by myself, somewliere in 
 the neighbourhood of Cheshunt. 
 
 72. '^^KG^YLKKIK Lyngh. 
 
 Char. Filaments compressed, attenuated, fragile, rarely an- 
 gular, loith, in most cases, two canals or grooves passing 
 round the centre of each frustule, indicated by the presence 
 of puncta on the lateral margins. 
 
 Derivation. From frango, to break ; In allusion to the 
 brittleness of the filaments. 
 
 The genus Fragilaria approaches very closely to that of 
 Diatoma as restricted in this work ; indeed the two genera 
 merge into each other, through Fragilaria virescens or rather 
 Diatoma virescens. The compressed character of the frond 
 is sufficient to distinguish it and all other DiatomacecB from 
 the genus Meloseira. 
 
 1. Fragilakia pectinalis Lyngb. 
 
 Plate XCV. Figs. 1. 4. 
 
 Char. Filaments large, dark broicn. Frustules in front view 
 quadrangular, two or three times broader than long, longi- 
 tudinally striated ivith two evident puncta on the lateral 
 
FRAGILARIA. 413 
 
 margins ; in end view curved with slight constrictions at 
 each extremity, striated, 
 
 /3 undulata Kalfs. — Convex margin of end view of the 
 frustule icith two indcjitations ; centre of concave margin 
 ■prominent. 
 
 Ag. Syst. p. 7. ; Consp. Diat. p. 62. ; Grev. in Br. Fl. 
 vol. ii. p. 403. ; Harv. Br. Alg. p. 197. Conf pectinalis 
 Dillw., t. 4. ; Eug. Bot. t. 1611. ; Jurg, Dec. 18. No. 12. 
 Fragilaria grandis Ehr., Die Infus. p. 203. 1. 15. fig. 11.; 
 Pritch. Infus. p. 220. — /3 vndulata, fig. 171. ; Ralfs, in 
 Annals, vol. xii. pi. 2. fig. 3, F. pectinalis Ehr., pi. xvi. 
 fig. 1 a ; Jenner, loc. cit. p. 202. 
 
 Hah. Everywhere common in pools, ditches, &c. — /3 un- 
 dulata. Drws Ardudwy, near Barmouth : Rev. T. Sal- 
 wey. Scrubbs, Colebrook Park : Mr. Jenner. 
 
 The filaments of this species and others of the genus vary 
 exceedingly in size, or rather in diameter, on account of the 
 cells of the species of the genus developing themselves in 
 breadth as well as length, and this developement occasions 
 the greatest variations in the width of the cells, compared to 
 their length : thus sometimes the cells are longer * than broad 
 in the very slender filaments ; at others, as in the longest 
 threads, they are six or seven times broader than long, but 
 usually their breadth exceeds their length only by three or 
 four times. 
 
 On the anterior surfiices of the frustules at either extremity, 
 but not extending entirely across them, a delicate row of strire 
 may be detected : these add greatly to the beauty and interest 
 of the plant, and do not appear hitherto to have been described : 
 they are doubtless formed by the continuation of the stride 
 observed in the end ^iew of the frustule. ^Ir. Jenner has 
 
 * The terms lengtli and hrcudth, M-hon employed in this work in the 
 description of the Diatomaccce, are nsed in the same sense in which they 
 are employed in the definitions of the Confervce, the breadth of the frnstule 
 corresponding to the diameter of the filament, and the length to its longi- 
 tude. In the Diutoviaccce the breadth of the frustule usually exceeds the 
 length. 
 
414 DIATOMACE^. 
 
 verified my observation on these minute strias : when first I 
 observed them, I thought that they were found only in the 
 undulated variety of the plant, and that this therefore might 
 form a distinct species. I am now satisfied, however, that the 
 striaj are to be found in every well-developed specimen ; and 
 the difference observed in the end view of the frustules in 
 certain species is indicative of merely a condition of the 
 plant. 
 
 A remarkable state of this species has been met with by 
 Mr. Kalfs and Mr. Jenner. In this, within each frustule is 
 enclosed apparently a second frustule of a more or less oval 
 form, and striated laterally in the same way as the extremities 
 of the cells. 
 
 Occasionally it happens in this and in other species and 
 genera of DiatomacecB that the cells in their front aspect 
 are not in the form of a parallelogram, but somewhat cuneate : 
 this occurs in consequence of tlie frustule being divided ob- 
 liquely, and not by a straight line. 
 
 Tlie frustules, Mr. Ralfs observes, have sometimes a central 
 pellucid spot, which does not appear to be connected with the 
 endochrome. 
 
 When recent, Fragilaria jjectinalis is of a dark brown, but 
 in drying it turns to a greyish green, Avith a metallic lustre. 
 
 2. Fragilaria hyemalis Lyngh. 
 Plate XCV. Fig. 5. 
 
 Char. Filaments very fragile. Frustules long. Sides slightly 
 emarginate, iiuncta very small. End view ellij)tico-lanceo- 
 late, tvith from two to seven or eight well-marhed stria, 
 which terminate in distinct j)uncta along the anterior ter- 
 minal margins of the frustules. 
 
 Lyngb. t. 63. ; Ag. Syst. p. 7. ; Consp. Diatom, p. 63. ; 
 Kiitz. in Linna?a, 1833, p. 72. Fragilaria confervoides 
 Grev., in Br. Flor. vol. ii. p. 403. ? Harv. Br. Alga3, 
 p. 197. ; Ralfs, in Annals, vol. xii. pi. ii. f. 3. 
 
 Fragilaria turgida Ehr., Infus. pi. xv. f. 1 3. 
 
FRAGILARIA. 415 
 
 Hah. In freshwater pools and rivulets, Sussex : Mi'. Bor- 
 rer. Llyn Prefeddyr, near Barmouth : Rev. T. Salwey. 
 Aberdeen : Dr. Dickie. Stevenston : Rev. D. Lands- 
 horougli. Ballantrae, Ayrshire : Mr. W. Thoinpson. Dol- 
 gell}^ Tavistock, and Trenteshoe, Devonshire ; Pen- 
 zance, Cornwall : 3Ir. Rolfs. 
 
 This is a smaller species than Fragilaria pectinalis, differ- 
 ing from it also in the slightly emarginate sides of the frustides, 
 the elliptico-lanceolate form of their end view, and the paucity 
 and decided character of the stria; seen on the end surface. 
 
 The filaments are so fragile, that the frustules separate on 
 the slightest touch, so that it is rare to meet with a filament 
 of any length. In most specimens the frustules are as long 
 as broad, and some even longer ; but in others, again, they are 
 two or thz'ee times broader than long. The filaments not so 
 unequal as in the other British species of the genus. When 
 recent, it is of a dark brownish colour, becoming Avhitish 
 brown in drying. 
 
 There can be no doubt of the correctness of the reference 
 to Ehrenberg. 
 
 3. Fragilaria rhabdosoma Ehr. 
 
 Plate XCV. Fig. 6. 
 
 Char. Filaments muclCcompressed. Frustules usually maiiy 
 times broader than long ; in the end view lanceolate, and 
 tvithout stria. 
 
 Ehr. Die Infus. p. 204. t. 15. f. 12, Frag, pectinalis 
 Kiitz., in Linnaja, 1833, p. 73. ? Frag, tennis Ag., Con- 
 spect. Diatom, p. 63. ? llalfs, in 1. c. p. 108. ^\. xi. fig. 4. 
 F, hijmnctata, F. angusta, F. scalaris, and F. dioptltalma 
 Ehr., t. XV. F. rhabdosoma Jenner, in Flora of Tun- 
 bridge Wells, p. 202. 
 
 Hab. Common in pools and ditches. 
 
 The exceedingly narrow frustules, and the lanceolate form 
 
416 DIATOMACEiE. 
 
 of the end view of these, will distinguish this plant from all 
 other freshwater species. 
 
 It is of a pale brown when recent, becoming in drying of a 
 greyish hue with a silvery lustre. 
 
 73. EUNOTIA Ehr. 
 
 Char. Frustulcs free, striated laterally, with two superficial 
 grooves running round each, and indicated hy lateral 
 puncta. 
 
 This genus differs only from Fragilaria in that the frus- 
 tules never form filaments, as in that genus. 
 
 1. EUNOTIA Arcus Ehr. 
 
 Plate XCVII. Fig. 5. 
 
 Char. Frustules elongated, striated. Li front view qria- 
 drangular, with straight sides. In lateral aspect narrow, 
 curved, constricted towards either extremity. 
 Eunotia A7'cus, Bericht. der Akademie d. Wissensch. zu 
 Berlin, 1837, p. 45. ; Ehr. Die Infus. t. 21. fig. 22. ; 
 Eunotia monodon? Ehr. ; Ealfs, in Annals, vol. xv. p. 459. 
 pi. xiv. fig. 1 ? ; Jenner, in loc. cit. p. 202. 
 Hab. Cheshunt: A. H. H. Piltdown Common: Mr. 
 Jenner. Penzance : Mr. Ralfs. 
 
 A distinct and not uncommon species. 
 
 2. Eunotia Diodon Ehr. 
 Plate XCVII. Fig. 6. 
 
 Char. Frustules elongated. In front view quadrangular, 
 
 with straight sides. Convex margin of lateral aspect 
 
 hidentate. 
 
 Eunotia Diodon, Bericht. der Akad. d. Wissensch. zu Ber- 
 
 , lin, 1837, p. 45. ; Die Infus. p. 192. t. xxi. fig. 13. ; 
 
MERIDTON. 417 
 
 Jcuner, loc. cit. p. 292. ; Ealfs, in Annals, vol. xv. 
 
 p. 460. pi. xiv. fig. 2. ; Bailey Amer. Bacil. pi. ii. f. 29. 
 Hah. Piltdown Common : Mr. Jenner. 
 The teeth or processes in this species are obtuse and but 
 little elevated. 
 
 3. EuNOTiA Triodon Ehr. 
 Plate XCVII. Fig. 7. 
 Char. Frustules in lateral view semi-lunar, having three 
 obtuse teeth on the convex margin. 
 Eunotia Triodon Bericht. der Akademie d. Wissensch. zu 
 Berlin, 1837, p. 45.; Die Infus. t. xxi. fig. 24.; Jen- 
 ner, in Fl. of Tunbridge Wells, p. 202. ; Ralfs, in 
 Annals, vol. xv. p. 461. pi. xiv. fig. 23 ?; Bailey, Amer. 
 Bacil. pi. ii. f. 30. 
 Hab. Cold bath spring : Blr. Jenner. 
 
 A distinct species, noticed hitherto, I believe, only by INIr. 
 Jenuer. 
 
 4. Eunotia Tetraodon Ehr. 
 Plate XCVII. Fig. 8. 
 Char. Frustules in lateral view semilunar, toitlt foun obtuse 
 teeth on the convex margin. 
 Eunotia Tetraodon Mittheilungeu der Berl. Naturforscli. 
 Freunde (Berl. Staatszeituug, April 1837); Die Infus. 
 p. 192. t. xxi. fig. 25. ; Ralfs, in Aunals, voL xv. p. 461. 
 pi. xiv. fig. 4. ; Bailey, 1. c, pi. ii. f. 31. 
 Hab. Piltdown Common, Sussex, and Weston Bogs near 
 Southampton : 3Ir. Jenner. 
 
 B. Frustules icedge-shapcd. 
 74. MERIDION Leiblein. 
 
 Char. Frustules cuncatc, united so as to form segments of 
 circles or sjnrals. 
 
 E E 
 
418 DIATOMACE^. 
 
 Derivation. From /Ltspt?, a jjortion or jmrticle. 
 
 This is a very natural genus, differing from Fragilaria in 
 the cuneate form of the frustules in the front view, and atte- 
 nuated outline in the end or lateral aspect, and from Stylaria 
 in the number of frnstules, which cohere, and which form 
 more or less considerable portions of circles. 
 
 1. Meridion circulare Ag. 
 
 Plate XCVI. Figs. 1—6. 
 
 Char. Frustules very variable in size, broad margin, punc- 
 tated. Articulating surfaces clavate, strongly striated; 
 the ends of the strice appearing as p)uncta along the edges 
 in the front vieiv. 
 
 Meridion circulare Ag., Consp. Diatom, p. 40. ; Kiitz. Sy- 
 nop. Diatom, in Linnrea, 1833, p. 558. f. 37. ; Harv. 
 Manual, p. 205. Bleridion veriiale, p. 207. t. 16. f. 2. 
 Bailey's American Bacillaria, in Amer. Jour. Sci. Jan. 
 1842, pi. ii. f. 42. Echinella circida?'is Grev., in "Wer- 
 nerian Society, voh iv. p. 213. pi. viii. fig. 2., 1822; Scot. 
 Crypt. Fl. vol. i. t. 35. 31. circulare Ealfs, in Annals, 
 vol. xii. p. 458. pi. xviii. f. 1. ; Jenner, in Flora of Tun- 
 bridge WeUs, p. 206. 
 
 Hab. Common throughout Great Britain, in pools, &c. 
 
 The frustules of this very beautiful production exhibit all 
 the variety of sizes which characterise the different threads 
 of the Fragilarixe, and this resulting from the same cause, viz. 
 the lateral growth of the frustules. In the smaller and nar- 
 rower frustules the end view is broadly clavate ; in the larger 
 and deeper fi'ustules it is but slightly so, indeed almost linear. 
 I have occasionally met with frustules which have been very 
 perceptibly curved ; this form possibly arismg from the 
 spiral disposition of the lamina in the more perfect spe- 
 cimens. 
 
 Colour yellowish brown, assuming a green tinge in drying. 
 
MERIDION. 419 
 
 2. Meridion constrictum Ralfs. 
 Plate XCVI. Figs. 7, 8, 9. 
 
 Char. Articulating surfaces constricted at the broader end, 
 striated ; the stvinn forming puncta in the front view. 
 Meridion constrictum Ralfs, in Annals, vol. xiii. p. 458. 
 23l. xiii. fig. 2. ; Jenner, in Flora of Tunbridge Wells, 
 p. 206. 
 
 " This is one of the additions to our Flora, for which I 
 am indebted to Mr. Jenner, whose discoveries have added so 
 largely to the Sussex Cryptogamia^ and who is as indefatigable 
 in his researches as he is accurate in his observations. Mr. 
 Jenner finds it rather plentifully in the Cold Bath Spring, 
 Tunbridge Wells, growing on Frogilaria viresccns. I have 
 received from him both dried and recent specimens. In the 
 latter I find the frustules solitary or binate, the circles being 
 entirely broken up before the specimens reached me ; but 
 ISIr. Jenner informs me, that when gathered, they are united 
 together so as nearly to form a circle. As, however, they 
 are not arranged on a plane as in Meridian circulare, but 
 stand nearly erect, somewhat like the staves of a tub which 
 is broader above than below, when they are dry and fall 
 down they necessarily separate, and gcaps are produced in the 
 circular outline. In the dried si^ccimeus I find some of the 
 frustules arranged in a circle, which, however, exhibits the 
 gaps already noticed, whilst others seem to be fasciculated. 
 
 " The front view cannot be distinguished from a frustule 
 of JMcridion circulare, with Avhicli it agrees in size and form, 
 and also in having two conspicuous terminal puncta, and a 
 series along the lateral margins. As in MeiidioJi circulare, 
 the lateral surfaces have a few distinct, strongly marked 
 transverse striaj ; but they differ from it most remarkably in 
 the constriction below the apex." — lialfs. 
 
 In the very deep frustules the constriction is almost lost. 
 
 r, E 2 
 
420 DIATOMACE^, 
 
 Section ii. 
 Frond stipitate. 
 
 A. Frustules wedge-shaped. 
 
 75. GOMPHONEMA ^^. 
 
 Char. Frustules cuneate, solitary or geminate, supported on 
 a simple or branched and attached filiform stipes. 
 Derivation. From yo/jifo^, a ivedge, and v>]/j,a, a thread. 
 
 The extremities of the frustules in the front vleAv are 
 punctated and truncated, but in the lateral aspect rounded 
 or pointed ; tlie frustules are for the most part striated late- 
 rally, the striffi being interrupted by a longitudinal pellucid 
 line, in the centre of which is a depression often assuming 
 the appearance of a foramen. The genus bears a close re- 
 lation to the genera Styllaria and Lichmophora, the former 
 genus differing only from Gomphonema in the frustules being 
 invariably sessile, and the latter in having several frustules 
 associated together at the end of each branch of the stipes, 
 and forming a fan- like expansion. 
 
 The species of the genus Gomphonema are usually found 
 in freshwater. 
 
 a. Frustules iji lateral view constricted beloio the apex, so as 
 to appear urn-shaped. 
 
 1. Gomphonema geminatum Ag. 
 
 Plate XCVIII. Fig. 1. 
 
 Cha7'. Stipes much branched, tufted. Frustules large, cu- 
 neate, often geminate, puncta at the end obsolete. Lateral 
 surfaces urn-shaped, striated. Strife radiating. 
 
 Ag. Syst. p. 12.; Conspect. Diatom, p. 35.; Grev. Crypt. 
 Fl. t. 244. f. 2.; Kiitz. Synop. Diatom. In Llnna3a, 1833, 
 p. 569.; Harv. British Alga?, p. 207. Gomph. ampul- 
 laceum Grev., in Hook. Br. Fl. p. 410. G. geminatum 
 Ralfs, in Annals, vol. xli. p. 460. pi. xvlli. fig. 3. 
 
GOMPIIONEMA. 
 
 421 
 
 Hah. On rocks in subalpinc streams, Scotland : Dr. Gre- 
 ville. North of Ireland : Mr. D. Moore. Near Bandon, 
 CO. Cork : Prof. G. J. Allman. On dripjiing rocks, 
 near a waterfall at Carnlough, co. Antrim: Mr. W. 
 Thompson. Rapid streams at base of Cader Idris ; 
 and in the river above Dolgelly, North Wales: Mr. 
 Rolfs. 
 
 " This plant forms large cushion-like tufts on the rocks in 
 rapid streams. It is not in the least mucous, but is of a 
 spongy texture, being composed of densely interwoven 
 filaments. In a young state its colour is brownish, from the 
 frustules covering the surface; but as these fall off it becomes 
 whitish, and indeed not unlike a tuft of wool. Filaments 
 repeatedly dichotomous ; frustules much larger than in any of 
 the following species, simple or binate, linear cuneate, with- 
 out puncta at the upper end ; portions of the lateral surfaces 
 are frequently visible along the sides. Lateral surfaces urn- 
 shaped, broader than the front, Avith numerous transverse 
 dotted strite. There is a central longitudinal pellucid line, 
 slightly dilated at each end with a larger dilatation in the 
 centre ; the latter at first sight may be taken for a perforation, 
 Avhich it undoubtedly is not : from the central punctum the 
 stria? are somewhat radiant : the pellucid line docs not quite 
 extend to the upper end." — Ralfs. 
 
 2. GOMPHONEMA TRUXCATUM Ehr. 
 
 Plate XCVIII. Fig. 2. 
 
 Char. Frustules in front view cuneate, with tioo evident puncta 
 at the upper end. Lateral surfaces urn-shaped, striated. 
 G. truncatum and G. paradoxum Ehr., Abhandl. der 
 Akademie d. AVissensch. zu Berhu, 1831, p. 88. 1833, 
 p. 319. G. pohliciforjne Kiitzing, in Linna^a, 1S33, 
 p. 569, 570. t. xvi. fig. 50. G. truncatum Ehr., Die 
 Infus. p. 216. pk xviii. fig. 1. G. suhramosum Kiitz., 
 Synops. Diatom, p. 570. fig. 44. G. pohliccforme Ealfs, 
 in Annals, vol. xii. p. 461. pi. xviii. f. 4. G. cajntatum 
 
 E E 3 
 
422 
 
 DIATOMACEiE. 
 
 Ehr., Die Infus. ; Jenner, in Flora of Tunbridge Wells, 
 p. 206. 
 
 Hah. On aquatic plants in pools and ditches, near Hen- 
 field: JSIr.Borrer. Frequent in Sussex: Mr.Jenner. 
 Chesliunt and neighbourhood : A. H. H. Oswestry : 
 Rev. T. Salwey. Ilfracombe ; Swansea ; Dolgelly and 
 Bangor, North Wales : Mr. Rolfs. 
 
 A very distinct little species. The degree of constriction 
 of ^ the neck varies considerably in different specimens ; and 
 this circumstance doubtless led to the institution on the part 
 of Ehrenberg of the Gomphonema capitatum, which is as- 
 suredly but a state of G. truncatum. 
 
 3. GOBIPHONEMA ACUMINATUM Ehr. 
 
 Plate XCIX. Fig. 1. 
 
 Char. Frustules in front view cuneate and truncate. Lateral 
 surfaces constricted, acuminate, striated. 
 
 G. minutum Ag., Conspect. Diatom. 1832, p. 34. ; Grev. 
 in Hook. Br. Flor. vol. ii. p. 410. Gomph. acuminatum, 
 Abhandl. der Akademie d. Wissensch. zu Berlin, 1831, 
 p. 86. ; Bericht. der Akademie d. Wissensch. zu Berlin, 
 1836, p. 53., 1837, p. 44.; Die Infusor. p. 217. t. xviii. 
 fig. 4. G. mi7iutum Ralfs, in Annals, vol. xii. p. 462. 
 pi. xviii. f. 5. ; Jenner, in Flora of Tunbridge Wells, 
 p. 206. 
 
 Hab. Sussex : Mr. Jenner. Cheshunt, &c. : A. H. H. 
 Barmouth : Rev. T. Salwey. Trengwainton ponds, 
 near Penzance, and pond on Towednack Moor, near St. 
 Ives ; Dolgelly : 3Ir. Ralfs. 
 
 The degree of constriction and acumination of the frus- 
 tules would appear to be subject to very considerable variation. 
 As the species was published at nearly the same period, by 
 both Agardh and Ehrenberg, and apparently first by Ehren- 
 berg, I have retained the name of the latter which is infi- 
 nitely the more appropriate. 
 
GOMI'HONEMA. 423 
 
 b. Lateral surfaces not constricted below the apex. 
 
 4. GOMPHONEMA CRISTATUM Ralfs. 
 
 Plate C. Fig. 1. 
 
 Char. Frustules crested^ not constricted below the apex, striated 
 laterally. 
 
 Gomphoncma cristatum Ralfs, iu Annals, vol. xii. p. 463. 
 
 pi. xviii. fig. 6. ; Jenner, in loc. cit. p. 206. 
 Hah. On Conferva glomerata in a stream near Shorcham, 
 
 Kent, Dec. 1842. Farnham, Surrey : Mr. Jenner. 
 
 The only species with which this beautiful Gomphonema 
 could be confounded is G. acuminatum, from which it differs 
 in being altogether a smaller plant, and in the absence of the 
 constriction below the apex. 
 
 For its discovery naturalists are indebted to JNIr. Jenner. 
 
 5. GOMPnONElMA DICUOTOMUJM Kiltz. 
 
 Plate XCIX. Fig. 2. 
 
 Char. Frustules linear, cuneoie in front view, xoith very minute 
 terminal imncta. Lateral surfaces lanceolate, faintly 
 striated. 
 
 Kiitz. Synops. Diatom, p. 569. fig. 48. ; Ralfs, in Annals, 
 vol. xii. p. 463. pi. xviii. fig. 7. Gomph. gracile Ehr., 
 Die Infus. p. 217. t. 18. fig. 3. ; Pritch. Lifus. p. 227. 
 G. angustum? Ag., 1831. 
 
 Hab. Trengwainton ponds, near Penzance : Mr. Ralfs. 
 
 The frustules of this species somewhat resemble those of 
 Gomphonema Berkeleyi, but they are more elongated, nar- 
 rower, often nearly linear, and their lateral surface lanceolate, 
 and not clavate. 
 
 6. Gomphonema Berkeleyi Grev. 
 
 Plate C. Fig. 2. 
 
 Char. Frond forming large mucous masses. Stipes branched, 
 
 E E 4 
 
424 DIATOMACE^. 
 
 entangled. Frustules short, triangular, loith two con- 
 spicuous puncta at the end. Lateral surfaces ohovate or 
 suh-clavate. 
 
 /3 Frustules scattered, more firmly attached to the stipes, 
 ivhich is more evident. 
 
 Grev. in Hook. Br. Fl. vol. ii. p. 409. ; Harv. Br. Alg. 
 13.207. Gomph.9 olivaceaYXxw, Die Infus. 218. t. 18. 
 f. 9. ; Pritch. Infus. p. 228. Exilaria minutissima 
 Berk., Br. Alg. p. 22. t. 7. f 1. Bliridion vernale Ag., 
 Consp. Diatom, p. 55Q. £31. Gomph. geminatum 
 Kiitz., Alg. Aq. dulc. No. 13. Gomph. Leihlini Kiitz., 
 Synop. Diatom, jd. 568. fig. 46. 
 
 Hab. On stones, &c., In freshwater spring, King's Clifi^, 
 ISTortliamptonsliire : Rev. M. J. Berkeley. Heufield, Sus- 
 sex : Mr. Borrsr. Mayfield, Sussex : Mr. Jenner. Yar- 
 mouth : 3Ir. Dawson Turner. Biver Severn, near 
 Shrewsbury : Mr. Leighton. Cheshunt, Herts, and River 
 Lea : A. H. H. At the base of Bandon Mountains : 
 Mr. Andrews. — /3. Duddingston Loch : Dr. Greville. 
 
 The stipes in the species in its ordinary state, owing to its 
 being imbedded in a mucous matrix, is often with difficulty 
 discernible. The frustules approach rather closely to those 
 of Gomph. dichotomum; than which, however, they are shorter, 
 broader, and more decidedly cuneate. 
 
 7. GOMPHONEMA MINUTISSIMUM Ag. 
 
 Plate C. Fig. 3. 
 
 Char. Frustules curved, striated; terminal puncta well 
 marked. Lateral surfaces clavate, striated. 
 
 Kiitz. Syn. Diatom, p. 567. fig. 43. ; Ehr. Die Infus. 
 
 p. 219. t. 18. fig. 5.; Pritch. Infus. p. 228. Gomijh. 
 
 curvotum Kiitz., Syn. Diatom, p. 567. f. 51. ; Kiitz. 
 
 Aq. dulc. No. 76. 
 Hah. Shrewsbury : Mr. Leighton. Shoreham, Kent : 
 
COCCONEMA. 425 
 
 Mr. Jcnner. Cbesbunt : A. H. 11. iS^eur Dublin : Prof. 
 G. J. Allman. Swansea : 3Ir. Ralfs. 
 
 " Tbis species differs from all tbe foregoing in its curved 
 frustules, in baving a notcb on one only of tbe lateral margins 
 and two stria; passing down tbe frustule and connecting tbe 
 upper and lower puncta."-— Ralfs. 
 
 76. PODOSPHENIA. 
 
 Char. Frustules iccdge-shaped, never constricted. Stipes none, 
 or very short. 
 
 Derivation. From ttovs, afoot, and (K^t]!', a wedge. 
 
 Tbis genus differs from Gomphonema in tbe absence of a 
 regular and brancbed stipes. In tbeir young condition tbe 
 frustules are attacbed in tbe same manner as those of tbe 
 Exilarias. 
 
 1. PODOSrnENIA? OCULATUM. 
 
 Plate C. Fig. 9. 
 
 Char. Frustules large, m front view ivcdge-shajjed ; laterally 
 ovoid, striated. StriiB short. 
 
 Gornphonema oculatum Kutzing, in Liuna3a, p. 568. f. 45. 
 
 G. rotundatum Ebr., xviii. f. 7. 
 Hab. By tbe side of a rapid stream, parasitic on Lynghya 
 
 zonata, at Corbam, near Bristol: Mr. Tkwaites. 
 
 A very beautiful species, for an examination of wbicb in a 
 recent state I am indebted to INIr. Tbwaites, its first and 
 only discoverer in tbis country. 
 
 B. Frustules semi- elliptical. 
 
 77. COCCONEMA. 
 
 Cdiar. Frustules stipitate, semi-elliptical, icith a longitudinal 
 furrow, striated. 
 
426 DIATOMACE^. 
 
 Derivation. From kokkos, a grain, and vqfia, a thread. 
 The frustules in this genus may be compared to a grain of 
 wheat in form. 
 
 1. COCCONEMA LANCEOLATUM Ehr. 
 
 Plate CI. Fig. 1. 
 
 Char. Frustules large, semi-lanceolate, straight, obtuse. 
 
 Gomphonema lanceolatum Agardh, Conspect. Crit. Diatom. 
 1831, p. 34. Gomphonema iPaltonophord) lanceolatum 
 Kiitz., in Linntea, 1833, p. 38. ; Jenner, in Flora of 
 Tunbvidge Wells. Cocconema lanceolatum Ehr., Die 
 Infus. p. 224. pL xix. fig. 6. 
 
 Hah. Waterfall at Hill Park, Westerham, and at Shore- 
 ham, Kent ; Parham, near Pulborough, &c. : Mr. Jenner. 
 Cheshunt: A.H.H. 
 
 This is a very fine and distinct species. 
 
 2. Cocconema cymbiforme Ehr. 
 
 Plate CI. Fig. 2. 
 
 Char. Frustules slightly curved, narrow, attenuated, sub- 
 acute. 
 
 Frustuliacg}7ibiforjnisKMz., in Jj'mnxa, 1833, p. 540. t. 15. 
 
 fig. 9. Cocconema cymbiforme Ehr., Die Infus. p. 225. 
 
 pL xix. f. 8. ; Jenner, in Fl. of Tuubridge Wells. 
 Hah. New River reservoir, Cheshunt : A.H.H. 
 
 This species might readily be confounded with the previous 
 one, from which it is to be distinguished by its smaller, nar- 
 rower, more attenuated and somewhat curved frustules. 
 
 3. Cocconema cistula Ehr. 
 
 Plate CI. Fig. 3. 
 
 Char. Frustules crcscentic, ventricose, obtuse, often in pairs. 
 
CYMBELLA. 427 
 
 Coceoneina cistula Elir., Die Infus. p. 224. pi. xix. f. 7. ; 
 Jenuer, in Fl. of Tunbridge Wells. Cymhella copulata 
 Breb. and Godey. N.geminata? Turp. (1828). 
 
 Hah. Frequent in Sussex : ilfr. Jenyjer. Cheshunt: ^.-K-H. 
 
 The frustules in this siDecies are shorter than in those pre- 
 viously described, more ventricose and obtuse. In C. lanceo- 
 latum the frustules are straight, in C. cymhiforme but slightly 
 curved, while in C. cistula they are considerably so. 
 
 4. COCCONEMA VENTRICOSA ? Hass. 
 
 Plate CI. Fig. 4. 
 
 Char. Frustules small, straight, ventricose, obtuse. 
 
 Cocconcma? gihbum Ehr., Die Infus. p. 225. pL xix. f. 9.; 
 Jenuer, in Flora of Tunbridge Wells. Cymhella ven- 
 tricosa Ag. ? Flor. Bot. Zeit. ; Breb. and Godey. 
 Hah. Cheshunt : A. H. H. Waterfall at Harrison rocks : 
 Mr. Jenner. 
 
 This is the smallest species of the genus which has hitherto 
 been described. From Cocconema phoenicenteron, with which 
 it might be confounded, it differs in size and in the frustules 
 not being curved. 
 
 78. CYMBELLA //«55. 
 
 Cliar. Frustules cymhiform, striated, sulcated, not stipitate. 
 Derivation. The diminutive of cymha, a boat ; in allusion 
 to the form of the frustules. 
 
 This genus differs from Cocconema only In the frustules 
 not being stipitate as they are in that genus. Although not 
 stipitate, the frustules frequently are attached in the entire 
 length of their flat surface to other Alga, often to Clodo- 
 phora crispata. The Cymhella of Agardh embraces species 
 belonging to several distinct genera, and not one of those here 
 described under the name of Cymhella. The following are 
 
428 DIATOM ACEiE. 
 
 species of the genus Cymhella : N. amphora Ehr., N. lineolata 
 Ehr., and N. JVestermanni. 
 
 1. Cymbella zebea Hass. 
 Plate C. Fig. 8. 
 
 Char. Frustules in side view semi-lanceolate, truncate ; in 
 
 front aspect elongated, quadrangular, zcith straight sides. 
 
 Strise distant, strongly marked, double. 
 Navicula zebra, Abhandl. der Akademie d. Wissensch. zu 
 
 Berlin, p. 262. ; Bericlit. der Akademie d. Wissensch. 
 
 zu Berlin, 1837, p. 53. Eunotia zebra Ehr., Die 
 
 lufus. p. 191. pi. xiv. fig. 7. pi. xxi. f. 19. 
 Hob. Cheshunt : A. H. H. On the moist conglomerate 
 
 sandstone cones near Cushendall, co. Antrim : Mr. 
 
 Moore. 
 
 This fine species approaches rather closely to the following, 
 from which it differs however in two respects ; in the strite, 
 which in Eunotia zebra are less numerous than in E. turgida, 
 and in the form of the frustule, which in the front view is 
 not attenuated at the extremities as it is in that species. 
 
 2. Cymbella tuegida Ilass. 
 
 Plate C. Fig. 7. 
 
 Char. Frustules semi-lanceolate, truncate at either extremity 
 in side view ; in lateral aspect narroioer toioards either 
 end than in the centre. 
 
 Navicula turgida, Abhandl. der Akademie d. Wissensch. 
 zu Berlin, 1830. Eunotia turgida, Bericht. der Aka- 
 demie d. Wissensch. zu Berlin, 1837, p. 45. ; Die Infus. 
 p. 190. t. xiv. fig. 5. 
 
 Hab. Storrington Common : 3fr. Jenner. 
 
 This species needs only to be contrasted with Cymbella 
 zebra, from which it differs in the two particulars indicated 
 in the description of that species, viz. in its finer and closer 
 
NAVICULA. 429 
 
 stria3j and in the f'rustules being attenuated in tlie front A'icw 
 towards either extr£mity. 
 
 3. CyMBELLA ? ARCUS Hass. 
 
 Plate C. Fig. 6. 
 
 Char. Frustules smooth. In front view contracted toioards 
 either end; in lateral aspect curved, attenuated, loith a 
 projection in the centre of the concave margin. 
 Navicula arcns, in Wicgmann's Archiv. fur Naturg. 183G, 
 p. 243, 244. ; Die Infus. p. 182. t. xxi. fig. 10. 
 
 Through this species the genera Cymhella and Navicula 
 would appear to be united, it agreeing with the first in the 
 semilunar and curved form of the frustule in its lateral view, 
 and with the latter in its attenuation in its anterior asiiect. 
 
 C. Form o/* frustules various. 
 79. NAVICULA ^ory. 
 
 Char. Frustules straight. In front view usually someivhat 
 attenuated toioards either end, extremities generally trun- 
 cate ; in lateral aspect boat-shaped, extremities often 
 acute. 
 
 Derivation. From navicula, a little boat. 
 
 This genus, as limited to those species, which the above 
 definition is intended to include, Avould appear to be an ex- 
 ceedingly natural one. 
 
 a. Frustules ivithout transverse strice. 
 
 1. Navicula ph(enicenteron Ehr. 
 Plate CII. Fig. 9. 
 
 Char. Frustules elongated, smooth, large. In front view 
 attenuated toicards either end; in lateral aspect extre- 
 mities lanceolate. 
 
430 DIATOMACEiE. 
 
 Navicula phcenicenteron Ehr., Die Infus. p. 175. t. xiii. 
 fig. 1. /?. 
 
 Hah. Cheshunt : A. H. H. — Var. B. Gardener Street : 
 Mr. Jenner. 
 
 It Is possible that the variety (B of Ehrenberg, which is that 
 here described under the name of N. phcenicenteroriy is really- 
 distinct. The frustule is not transversely striated, but several 
 longitudinal lines may frequently be noticed running along 
 the centre of each. 
 
 2. Navicula palea Hass. 
 
 Plate CII. Fig. 10. 
 
 Char. Frustules small, smooth. In front view attenuated, 
 with truncate extremities ; in side aspect lanceolate. 
 Navicula gracilis Ehr., Die Infus. p. 176. t. xiil. fig. 2. 
 Frustidia gracilis Jenner, in Flora of Tuubridge Wells, 
 p. 204. Cymbella avenacca Breb. et Godey. 
 Hah. Cheshunt : A. H. H. In the great bog near Forest 
 Row ; bogs at Fisher's Castle, &c. : Mr. Jenner. 
 
 This species resembles N. phoenicenteron in miniature. 
 
 3. Navicula amphisb^na Bory. 
 
 Plate CII. Fig. 5. 
 
 Char. Frustules elongated. In front view quadrangular, 
 with straight sides ; in lateral aspect oval, prolonged at 
 each end into a hlunt process. 
 Navicula amphishcena Bory, Encycl. Meth. 1824. Navi- 
 cula amphishcena Turpin, Diction, des Sc. Nat. 1828. 
 N. ventricosa, Abhandl. der Aiademie d. Wissensch. zu 
 Berlin, 1830, p. 67. N. amphishcena, Abhandl. &c. 
 1833 (1832), p. 254. Frustidia cuspidata Kiitz., Lin- 
 nsea, 1833, p. 549. t. xiv. fig. 26. N. amphishcena, Die 
 Infus. p. 178. t. xiil. f. 7. Cymhella appendiculata 
 Godey et Breb. 
 
NAVICULA. 431 
 
 Hah. Cheshunt : A. 11. H. Aberdeen : Dr. Dickie. 
 A very well marked species. 
 
 4. Navicula plattstoma Ehr. 
 Plate CII. Fig. 6. 
 
 Char. Frustules elongated, quadrangular, ivith straight sides, 
 rostrated at each end. 
 Hab. Cheshunt: A. H. H. 
 Die Infus. p. 178. t. xiii. fig. 8. 
 A distinct and not uncommon species. 
 
 b. Frustules striated. 
 
 5. Navicula nodosa Ehr. 
 
 Plate CII. Fig. 7. 
 
 Char. Frustules small, in side vieio thrice undulated, ros- 
 trated at each extremity. 
 
 Die lufus. t. xiii. fig. 9. Frustulia nodosa ? Jenner, in 
 Fl. of Tunbridge Wells, p. 204. 
 
 Hah. On Ashdown Forest, near Forest Kow, between 
 Gardener Street and Hailsham, &c. : Mr. Jenner. 
 
 Mr. Jenner remarks that his specimens agree with Ehren- 
 berg's description and figures in every respect save that the 
 frustules were striated. It is probable that Ehrcnberg 
 overlooked the strias, and that these are always present. 
 
 6. Navicula injlqualis Ehr. 
 
 Plate CII. Fig. 13. 
 
 Char. Frustules in front view attenuated, toicards each end 
 truncate ; in side aspect unequal. 
 Navicula inaqualis, Bcricht. dcr Akademic d. Wisscnsch. 
 zu Berlin, 1836, p. 53. ; Die Infus. p. 184. t. xiii. f. 18. 
 
432 DIATOMACE^. 
 
 Hah. Gardener Street : Mr. Jenner. 
 
 Through this and the following species the genus Navicula 
 seems to pass into that of Cymhella, in wliicli genus indeed 
 the striated Navicula would not be very improperly placed. 
 
 7. Navicula gibba Ehr. 
 Plate CII. Fig. 4. 
 
 Char. Frustules in lateral view straight, narroiv, injlated; near 
 
 the centre gibbous. 
 Navicula gibba, N. unciata, Abhandl. der Akademie d. 
 
 Wissensch, zu Berlin, 1830, p. 64, 65. 68. 1831, p. 80. 
 
 Frustulia incrassata Kiitzing, Linna^a, 1833, p. 545. 
 
 t. xiii. fig. 17. Navicula gibba, Die Infus. p. 184. t. xiii. 
 
 f. 19. ; Jenner, in Fl. of Tunbridge Wells, p. 204. 
 Hab. Cheshunt : A. H. H. Ashdown Forest : Jack's 
 
 Wood Spring ; Chiltington Common, near Pulborongh, 
 
 &c. : Mr. Jenner. 
 
 8. Navicula lanceolata Ehr. 
 Plate CII. Fig. 14. 
 Char. Frustules lanceolate, extremities subacute. 
 
 Frustulia lanceolata Klltz., in Linncea, 1833, p. 14. t. xiii. 
 f. 13. Navicula lanceolata Ehr., Die Infus. p. 185. 
 t.xiii. fig. 21. 
 Hab. Sussex : ilfr. Jenner. 
 A well-marked little species. 
 
 80. EXILAKIA Grev. 
 
 Char. Frustules elongated, at first attached by a sessile and 
 undivided stipes, subsequently free, radiated, single, or bi- 
 nate. Junction surfaces frequejitly striated. 
 Derivation. From exilio, to issue forth ; in allusion to the 
 radiate disposition of the frustules. 
 
EXILAKIA. 433 
 
 This genus bears a slight resemblance to Gomphonema, the 
 frustules being attached in the young state of the species ; 
 they are not, however, triangular, as in the genus Gom- 
 phonema. 
 
 1. EXILARIA CAl'lTATA. 
 
 Plate XCVII. Fig. 1. 
 
 Char. Frustules large. In front view truncate at the ends ; 
 in side view dilated at both extremities into an obtusely 
 pointed head; striated. 
 Ehr. Die Infus. p. 211. pi. xxi. fig. 28. 
 
 This fine and beautiful species I found growing in im- 
 mense quantity in some ditches running parallel to the Barge 
 river near Cheshunt marshes. A few frustules of it have 
 also, I believe, been found by Mr. Ralfs. The frustules in 
 the front view are not to be distinguished from those of 
 Exilaria ulna ; the side view of E. capitata is, however, so 
 distinct, that it would be impossible to confound it with that 
 species. 
 
 2. Exilaria Ulna. 
 Plate XCVII. Fig. 2. 
 
 Char. Frustules large in the fully developed state. In front 
 view slightly dilated at the extremities, and truncate ; in 
 lateral aspect striated, extremities j)ointed. 
 Leuwenhoek's Philosophical Transactions, 1703 (1702), 
 fig. 8. L. K. Bacillaria ulna Nitzsch, Beltriige zur 
 Infusoricnkunde, 1817, p. 99. t. 5. Bacillaria commu- 
 nis Bory, in Diet. Class. 1822. Frustulia obtusa and 
 F. idna Agardh, Consp. Crit. Diatom. Echinclla fasci- 
 culata /3 truncata Greville, 1823 ; Scot. Crypt. Fl. 1. 
 t. xvi. Exilaria fascicidata Greville, 1827 ; Scot. 
 Crypt. Fl. V. f. 291 b. E. truncata Kiitz., in Linna^a, 
 1833, p. 560. Frustulia Ulna Ilarv., in ]Manual, p. 204. 
 P P 
 
434 • DIATOMACE^. 
 
 Synedra Ulna Ehr., Infus. p. 211. pi. xvii. fig. 1. ; 
 E. Ulna Jenner, in Flora of Tunbridge Wells, p. 204. 
 Hah. Common In ponds and ditches throughout Britain. 
 
 An exceedingly distinct species, not likely to be con- 
 founded with any other. The extremities of the frustules 
 would appear to undergo the same change as has been ob- 
 served in those of Diatoma elongatum^ and to become 
 somewhat dilated. 
 
 3. EXILAEIA FASCICULATA Kutz. 
 
 Plate XCVII. Fig. 3. 
 
 Char. Frustules small. In front view alternated at either 
 end ; in side view extremities acute. 
 
 Exilaria Vaucheri(B, E. fasciculata, in part, Klitz., in 
 Linnasa, 1833, p. 560, 561. t. xv. p. 38. 40. Synedra 
 fasciculata ISihr., Infus. p. 212. t. xvii. fig. 2. Exilaria 
 truncata Harv., In Manual, p. 204. Diatoma truncatum 
 Grev., in Hook. Br. Fl. p. 407. 
 
 Hah. Common in ditches, &c. 
 
 Tills Is a very distinct little species : the frustules are often 
 in pairs, and owing to these being frequently but imperfectly 
 separated from each other, a curved or fan-shaped lamina is 
 produced. 
 
 4. EXILAEIA LUNARIS. 
 
 Plate XCVII. Fig. 4. 
 
 Char. Frustules curved, small, slender, converging at the 
 extremities. 
 
 Synedra lunaris Ehr., Die Infus. p. 212. pi. xvii. fig. 4. 
 Exilaria lunaria Jenner, in Flora of Tunbridge "Wells, 
 p. 204. 
 
 A very distinct and pretty little species. 
 
NITZSCHTA. 
 
 435 
 
 81. GYROSIGMA Hass. 
 
 Char. Frustulcs straight in front view ; curved in the form of 
 the letter S in lateral aspect ; longitudinally striated, with 
 a central depression. 
 Derivation. From ^vpos, a curve, and acyfia, the letter S ; 
 in allusion to the form of the frustules. 
 
 1. Gykosigma hippocampa Hass. 
 Plate CII. Fig. 11. 
 Char. Frustules in front view attenuated toioards each extre- 
 mity ; in side aspect lanceolate, curved, longitudinally 
 striated. 
 Nav. hippocampus Ehr., Die Infus. p. 180. t. xiii. f. 11.; 
 Frustulia hippoca}7ipus Jenner, in Fl. of Tunbridge 
 Wells, p 204. 
 Hab. Cheshunt: A. H. H. Olford and Shoreham, Kent : 
 Mr. Jenner. 
 
 In the same genus with this species should be placed the 
 Navicida sigma, N. scalprum, and N. curvida of Ehrenberg.* 
 
 82. NITZSCHIA Hass. 
 Char. Frustules curved in front vieio in the form of the letter 
 S; in lateral aspect straight, transversely striated, and icith- 
 out a longitudinal furroto and central depression. 
 Derivation. Named in memory of M. Nitzsch. 
 The single species upon which this genus is founded 
 accords with Exilaria in all its characters, save in the seg- 
 moidal curvatures of the frustulcs. 
 
 1. NiTZSCHIA ELONGATA Hass. 
 
 Plate CII. Fig. 12. 
 
 Char. Frustulcs linear, lengthened, xoith truncate extremities in 
 
 * The Sigmatella of Kutzing, the construction of which term is some- 
 what objectionable, is synonymous with Gyrosigma. 
 
 FF 2 
 
436 DIATOMACE^. 
 
 front view ; straight, attenuated at either end in lateral 
 aspect. 
 
 Bacillaria sigmoidea Nitzsch, Beitrage z. Infusorienkunde, 
 1817 (1816), p. 104. Cymhella sigmoidea Agardh, 
 Consp. Crit. Diatom. 1830, p. 11. Frustulia Nitzschii 
 Klitz., Linnaja, 1833, p. 554. t. xiv. fig. 33. Navicula 
 sigmoidea Ehr., Die Infus. p. 182. t. xiii. f. 15. t. xxi. 
 f. 11. 
 
 A well-marked species, Avhich I conceive to be generically 
 estranged from Gyrosigma hipjiocampa by the difference in 
 the curvature of the frustule, the arrangement of the strife, 
 and the absence of the longitudinal furrow and central de- 
 pression. 
 
 83. SPHINCTOCYSTIS Hass. 
 
 Char. Frustules contracted in the centre; longitudinal furrow 
 and central depression absent 9 
 Derivation. From a(j)LyKros, constricted, and kvctti?, a cell. 
 
 1. Sphinctocystis librilis Hass. 
 Plate CII. Fig. 3. 
 
 Char. Frustules transversely striated, elongated. In front view 
 quadrangular, with straight sides and truncate extremities ; 
 in lateral aspect constricted in the centre ivith obtuse erids. 
 Navicula lihi'ilis Abhandl. d. Akademie d. Wissensch. zu 
 Berlin, 1831, p. 81. 1833, p. 267. note. Frustulia 
 quinquepunctata Kiltzing, Linnaja, 1833, p. 554. t. xiv. 
 f. 28.; Die Infus. p. 185. t. xiii. f. 21. Frustulia li- 
 brilis Jenner, in Fl. of Tunbridge AYells, p. 204. 
 
 Hab. Cheshunt : A. H. H. Aberdeen : Dr. Dickie. War- 
 burton, Lewes, &c. : 3Ir. Jenner. 
 
 A very curious species, which, on account of the central 
 constriction and absence of the longitudinal furrow and cen- 
 tral depression, I have ventured to make the type of a dis- 
 tinct ffenus. 
 
FRUSTULTA. 
 
 437 
 
 84. AULACOCYSTIS Hass. 
 Char. Frustules jiroduced, longitudinally sulcated. 
 Derivation. From avka^^ a groove, and Kuans, a cell. 
 
 1. AULACOCYSTIS PELLUCIDA Hass. 
 
 Plate CII. Fig. 8. 
 
 Char. Frustules elongated, narroio, attenuated at each extre- 
 mity. 
 
 Navicula? pellucida, Die Infus. p. 176. t. xiii. fig. 3. 
 Frustulia pellucida Kiitz., in Linuajn, 1833, p. 543. 
 t. xiii. fig. 11.; Jenner, in Fl. of Tunbridgc Wells, 
 p. 204. 
 
 Ilab. Ashdown Forest, and at Shoreliam, Kent; between 
 Tunbridge Wells and the High Rocks : il/r. Je7mer. 
 
 There can be no doubt of the propriety of separating this 
 species from the genus Navicula of Ehrenberg. 
 
 85. FRUSTULIA Kiltz. 
 
 Cliar. Frustules elongated, quadrangxdar, with tico longitudinal 
 grooves and two central depressions. 
 Derivation. Yvom frustuhan, a small fragment. 
 
 I must confess that 1 do not exactly understand the struc- 
 ture of the single species which I propose to retain in the 
 genus Frustidia. It is possible that to this genus should be 
 referred those species of Navicida which have striated frus- 
 tules ; and, if not to this genus, possibly those species should 
 be regarded as Cymhellce. 
 
 1. Frustulia? \iuit>i^ Kutz. 
 
 Plate CII. Fig. 2. 
 
 Char. Frustules large, elongated. In front view quadrangu- 
 lar, with straight sides and truncate extremities ; laterally 
 slightly infiatcd in the centre, with rounded ends. 
 
 F F 3 
 
438 DIATOMACEiE. 
 
 Frustulia viridis Kiitzing, Linntea, 1833, p. 551. Navicula 
 viridis Ehr., Die Infus. p. 182. t. xiii. f. 16. t. xxi. 
 fig. 12. Frustulia viridis Jenner, in Fl. of Tunbridge 
 Wells, p. 203. Nav. biceps ? Bory, Encyc. Meth. 11824. 
 
 Hah. Frequent in Sussex : Mr. Jenner. Cheshunt : 
 A. H. H. Aberdeen : Dr. Dickie. Ireland : Mr. Moore. 
 
 This is one of the finest and most beautiful of all the 
 Diatomacece, In young specimens the frustules are not at all 
 or scarcely inflated in the centre. 
 
 86. SUKIRELLA Turp. 
 
 Char. Frustules large, solitary, quadrangular ; angles -pro- 
 duced, striated. 
 
 Derivation. Named in honour of Dr. Siiriraz/. 
 
 This seems to be a well-marked genus. To it should be 
 referred, in addition to the two species described below, 
 Navicula? splendida, N. ? undulata, N. ? constricta, which would 
 stand thus : Surirella splendida, S. constricta, and ^S*. undulata. 
 The two latter species differ from all the others in the trans- 
 verse strias being in single and not double series, that is, they 
 pass entirely across the frustule. This genus seems to have 
 been indicated by Ehrenberg. 
 
 1. Surirella biseriata Breb. 
 
 Plate CII. Fig. 1. 
 
 Char. Frustules in front view quadrangular, about three 
 times as long as broad, icith straight sides and truncate ex- 
 tremities ; in lateral aspect oval, with pointed ends. 
 
 Navicula? hifrons Ehr., Die Infus. p. 186. t. xiv. fig. 2. 
 
 Sui^irella biseriata Jenner, in Fl. of Tunbridge Wells. 
 Hab. Ashdown Forest, Piltdown Common, Broadwater 
 
 Forest, and Warbleton : 3Ir. Jenner. 
 
ENCYONEMA. 439 
 
 2. SURIRELLA JeNNERI Ilass. 
 
 Plate CII. Fig. 15. 
 
 Char. Frustules in front view obtuse at each extremity, and 
 ivith sfricB in double series ; end view quadrangular, each 
 angle being prolonged into a thin plate. 
 Surirella hifrons Jenner, loc. cit. p. 204. 
 Ilab. Warbleton : Mr. Jenner. 
 
 A very distinct and beautiful production, having no re- 
 lation with the N. bifrons of Ehrenberg. 
 
 87. ENCYONEMA Kiitz. 
 Char. Frustules cymbiform, enclosed within a membrane. 
 Derivation. From s^kvos, full, and vqfjia, a thread. 
 
 1. Encyonema prostratum Kiltz. 
 
 Plate C. Fig. 10. 
 
 Char. Frustules striated, straight, gibbous, small, enclosed 
 loithin a transparent membranous tube. 
 
 Encyonema prostratum Kiitz., Die Kreselsclialigcn, &:c. 
 p. 82. t. 25. f. 7. Encyonema paradoxion Kiitz., Synops. 
 Diatom. Monema prostj-atum Berk., Glean, of Br. 
 Alga3. Schizone^na ? prostratum Grev., in Hook. Br. FL, 
 p. 414. ; Harv. in Manual, p. 214. Encyonema j^ros- 
 tratum Jenner, in Fl. of Tunbridge Wells, p. 206. 
 
 Hob. On the boards of a sluice forming a thin, brown 
 mucous stratum : Rev. J. 31. Berkeley.. On the boards 
 of a sluice on Cheshunt JNIarshes : A. H. II. Bramble- 
 tye, near Forest Row, and in the stream which parts 
 Sussex and Kent, between Bodlam and Sandhurst. 
 
 k very singular and beautiful production, coming near to 
 Schizonema. 
 
 rr 4 
 
440 
 
 SUPPLEMENT. 
 
 Ztgnema insigne Hass. 
 
 Plate cm. Figs. 1, 2. 
 
 Char. Filaments of considerable size. Cells four or five 
 times as long as broad, inverted. Spires three, lax, in- 
 distinct. Sporangia oval, acute, producing considerable 
 inflation of the cells in which they are placed. 
 
 Hah. Ponds at AVadhurst, near Tunbridge Wells, and 
 Iden, near Rye : Mr. Jenner. 
 
 This fine species is rendered particularly interesting from 
 the circumstance of its being the only Zygnema with three 
 spires having inverted cells, all other species thus constructed 
 which have hitherto been discovered possessing, with but one 
 exception, in which tliere are two threads, only a single 
 sj)ire. 
 
 The filaments are about equal in size to those of Zygnema 
 rivulare, from which it is at once distinguished by its inverted 
 cells. 
 
 The credit of the discovery of this species is entirely due to 
 Mr. Jenner. 
 
 LyNGBYA rUSCO-PURPUEEA Hass. 
 
 Plate VIII. Figs. 1, 2. 
 
 Char. Filaments of considerable size, forming a broionish 
 green or purple stratum, glossy. Endochrome at first 
 homogeneous, subsequently granular. QvsawXQsfeio, about 
 five in each cell. 
 
COCCOCIILORIS. 441 
 
 Grev. Alg. Brit. p. 177. ; Hook. Br. Fl. vol. ii. p. 316. ; 
 Wyatt, Alg. Danm. No. 167. Conf. fusco-purpurea 
 Dillw. t. 92. ; E. Bot. t. 255. Co7if. atro-purpurea 
 Dillw. t. 103. ; E. Bot. t. 2085. Bangia atro-purpurea 
 Harv. p. 172. 
 
 Hab. Grand Canal, near Dublin : JV. H. Harvey. 
 
 Between this production and Lynghya zonata there is a 
 great structural resemblance, and assuredly the two species 
 do not differ generically from each other. 
 
 The interesting discovery of this being a freshwater pro- 
 duction was made by Mr. Harvey, who states that the locality 
 in which he gathered it had no communication with the sea. 
 
 COCCOCHLORIS CYSTIFERA Hass. 
 
 Plate CHI. Fig. 3. 
 
 Char. Granules rather large, mostly oval, contained in mucous 
 cysts, each cyst being occupied icith either one or two, but 
 sometimes, four granules. 
 
 Hab. Near Bristol : JSIr. Thwaites. 
 
 This and the two following species are particularly inter- 
 esting, from the fact of their exhibiting a cysted structure, 
 whereby a close relation is manifested in these species to 
 Hcematococcus, and which structure moreover it is probable 
 does in reality belong to all the species of the gemx?, Coccochloris, 
 but which escapes detection from the exceeding delicacy of 
 the organisation of many of the species. 
 
 COCCOCHLORIS VARIABILIS HasS. 
 
 Plate CHI. Fig. 4. 
 
 Char. Granules in the dried condition not having any regular 
 form, rather small. Cysts somewhat large, containing 
 one, two, or four granules, mostly spherical. 
 Hab. On thatch, Northiam : 3Ir. Jenner. 
 
442 SUPPLEMENT. 
 
 It is only in the exterior and more consistent portions of 
 the frond that the cysts are clearly visible ; they are usually 
 spherical, but occasionally elongated and pointed at each end, 
 the contained granules being likewise elongated, and small, 
 almost abortive. 
 
 COCCOCHLORIS OBSCURA Hass. 
 
 Plate cm. Fig. 5. 
 
 Char. Granules small and circular. Cysts also small. 
 
 Hah. Limestone rocks, co. Antrim : Mr. Moore. 
 
 The granules and cysts in this species are much smaller 
 than in Coccocliloris cystifera, and not unfrequently a little 
 difficulty is perceived in detecting them. 
 
 " The Observations which have been made in these latter Times by the 
 help of the Microscope since we had the' Use and Improvement of it, 
 discover a vast Difference between Natural and Artificial Things. What- 
 ever is Natural, beheld through that, appears exq^uisitely form'd and 
 adorn'd with all imaginable Elegancy and Beauty. There are such in- 
 imitable Glidings in the smallest Seeds of Plants, but especially in the 
 Parts of Animals, in the Head or Eye, of a small Fly ; such Accuracy, 
 Order, and Symmetry in the Frame of the utmost minute Creatures, a 
 Louse, for Example, or a Mite, as no INIan were able to conceive without 
 seeing of them. Whereas the most curious Works of Art, the sharpest 
 and finest Needle, doth appear as a blunt rough Bar of Iron, coming from 
 the Furnace, or the Forge. The most accurate Engravings, or Emboss- 
 ments, seem such rude, bungling, and deformed Work, as if they had 
 been done with a Mattock, or Trowel ; so vast a difierence is there be- 
 twLxt the Skill of Nature, and the Rudeness and Imperfection of Art. 
 I might add, that the Works of Nature, the better Lights and Glasses 
 you use, the more clearer and exactly form'd they appear, whereas the 
 Effects of humane Art, the more curiously they are view'd and examin'd, 
 the more of Deformity they discover." — Ray. 
 
443 
 
 CONCLUSION. 
 
 I HAVE at length brought to a conchision a work which 
 for a considerable period has occupied much of my time iind 
 many of my thoughts. The feelings which have attended its 
 progress have been various : frequently, as on the discovery 
 of new species or facts, or the elucidation of some difficult 
 point, those of pleasure and satisfaction have prevailed ; occa- 
 sionally the opposite ones of doubt, and even despair, have 
 been predominant, as when I could not satisfactorily see my 
 way through difficulties ; these feelings, however, poignant as 
 they were while they lasted, were, I am happy to say, but of 
 short duration. Next day the task was usually resumed, and 
 all the doubt and perplexities vanished before renewed ex- 
 amination. 
 
 Those who follow after me in the investigation of this 
 department of natural science, still so rich in the discoveries 
 which it yields to deserving perseverance, while they Avill to 
 an extent scarcely inferior participate in the feelings of satis- 
 faction and delight which I have expressed, Avill, it is hoped, 
 share less those of an opposite character, now that the way 
 is opened out, and that a clearer view of the subject may be 
 obtained. 
 
 It was my intention to have made this History of the 
 British Freshwater Alg(B answer more closely to the title of 
 a liistory than in its present form it does, and that it should 
 have contained a chapter devoted to a historical consideration 
 of the subject ; this, although a difficult undertaking, would 
 laave been a most grateful one, for it would have afforded an 
 opportunity of mentioning in the terms of eulogy which they 
 
444 CONCLUSION. 
 
 deserve the names of all those who have made the Freshwater 
 AlgcB the object of their study. I had intended also to have 
 entered upon the consideration of the subject of classification, 
 and to have remarked on those which have hitherto been pro- 
 posed. I have been pi'evented from fulfilling these intentions 
 by the fact that this work has already greatly exceeded the 
 limits originally proposed for it. Should it be destined, how- 
 ever, to reach a second edition, chapters devoted to the con- 
 sideration of these two questions might, by the adoption of a 
 smaller type, be inserted with advantage. So much for the 
 omissions from the work. I w^ould now refer to a super- 
 fluity, and beg the Reader's indulgence for what I fear, 
 without explanation, might be deemed an unnecessary in- 
 trusion on his notice, the attachment of the Avriter's name 
 either to each new species or to those which for the first time 
 have been referred to other genera. This was done under the 
 impression that the practice was usual and customary. 
 
 That much still remains to be effected ere our knowledge 
 of the Freshwater Algcs shall be in any thing like a complete 
 state is evident from the number of species which for the 
 first time are introduced in this work. So numerous are these, 
 and so closely do many of them approach each other, that 
 there are some, I fear, and especially such as have not made 
 the AlgcB their study, and who therefore are scarcely in a 
 position to declare what amount of difference is of specific 
 value, who will be ready to assert, that the species have been 
 multiplied on insufficient grounds. Let such pause ere they 
 advance such an injurious assertion, which, like all asser- 
 tions, it is an easy matter to make, but more difficult to sub- 
 stantiate ; let them first bestow upon those species the care, 
 labour, and anxiety of their founder, and then their opinion 
 will be rendered valuable, and injustice be inflicted on no 
 party. 
 
 That superficial observers should arrive at the conclusion 
 that nearly allied species are states of one and the same pro- 
 duction is not so surprising, when we consider that the cha- 
 racters which distinguish species amongst the Algoi are fre- 
 quently not very obvious or prominent, and since even men 
 
CONX'LUSION. 445 
 
 of acknowledged skill and powers of observation have even 
 fallen into the error of asserting that a number of distinct 
 species are conditions of one and the same plant. Thus 
 M. G. Thuret, whose papers on the locomotive organs of the 
 spores of the Alga are the most interesting and important of 
 any which have ever appeared on the Algce, has committed 
 this mistake in reference to the Vmicherm, declaring that all 
 the species are states of one and the same production, and 
 comprising them all under the name of Vaucheria Ungeri: for 
 a refutation of this position, see the figures of the species of 
 this genus contained in the ])resent work. Other observers, 
 again, even go further than this, not allowing the Vaucherm 
 to rank as species at all, but stating that they are merely 
 stages in the growth of mosses. Statements of this trans- 
 formation of AlgcE into mosses, &c., are wholly without found- 
 ation, and wholly undeserving of credit. 
 
 The end is drawing near. How strongly are we mortals the 
 creatures of habit and" association ! with what reluctance do 
 Ave quit a place, a companion, or a pursuit with which we 
 have been long connected, and it may be not altogetlier 
 agreeably so ! The prisoner of Chillon felt regret at quitting 
 the prison of which for so many years he had been the soli- 
 tary inhabitant : each of us can call to mind the pain which 
 we have experienced in leaving a companion with whom we 
 have been long associated, even though that companion may 
 not have been really esteemed by us; and I must confess that 
 I cannot banish some feeling of regret at the conclusion of 
 this undertaking, which has for so long a time interwoven 
 itself with my thoughts, notwithstanding that there are several 
 considerations which render the completion of the task a sub- 
 ject of congratulation. 
 
 Although in a few days I shall cease to be occupied with 
 this work, the interest Avith Avhich the subject of which it 
 treats has inspired me will not have ceased. In the fact 
 that I have devoted so much time to its consideration there 
 is no regret : I am still willing to devote more to it ; and I 
 shall gladly at all times avail myself of the correspondence of 
 all or any who may take an interest in the AJgoi, and will 
 
446 CONCLUSION. 
 
 favour me with their communications, and assist them in the 
 determination of the productions of the localities in which 
 they reside. 
 
 Apart from the interest attached to the examination of the 
 individual species, there is a source of pleasure in the addi- 
 tional interest which is imparted to our rambles : each sj^ot 
 that Ave pass is rendered doubly interesting — is almost hal- 
 lowed — by the recollection of its being the place in Avhich we 
 first became acquainted with some rare or new production, 
 which at the time awakened our curiosity, stimulated inquiry, 
 and elicited admiration. 
 
 I cannot do better than conclude these few remarks in the 
 appropriate language of the eloquent Vaucher : — 
 
 " I fear not to propose similar occupations to all men who 
 have a taste for observation, and who love the beauties of 
 nature. If their position and their fortune permits them 
 some leisure, they cannot employ it more happily. When- 
 ever natural history has a fixed purpose, and that some 
 object of study is made choice of, the labours to Avhich we 
 submit ourselves become more agreeable, and at the same 
 time more useful. Those botanists who shall make dis- 
 coveries in this science, which presents so vast a field, not 
 only will experience a real pleasure, but moreover they will 
 preserve the remembrance of it. Each time that they ap- 
 proach the place which has been the theatre of them, it will 
 recal to them the objects with which it is associated. For 
 myself I avoAV that I see not without interest the place 
 where I perceived for the first tfme the floating seeds of my 
 ectospermes, nor that where I obtained the network of the 
 hydrodictyon in its first development. Tlie species of Con- 
 fervcB even which I have long visited, and the fructification 
 of which I have ascertained but with difiiculty, inspire in me 
 a kind of attachment Avhich I feel more than I am able to 
 express. I love to see spring up and develope themselves 
 near me those species with which I am, so to speak, in ac- 
 quaintance. I exj)erience some pain if I know that any 
 one of them come to be destroyed. This acquaintance 
 Avhich I have acquired seems to me a kind of empire Avhich 
 
CONCLUSION. 447 
 
 1 desire still to extend : I say to myself sometimes, when 
 shall I quit the environs of Geneva ? When shall I behold 
 the borders of the sea ? the Mediterranean, the Ocean ? 
 that wandering Confei-va of which LinnaBus speaks, which 
 floats upon the sea as our Conjuf/atcB float upon the waters ? 
 I do not believe that elsewhere a happier kind of life is to 
 be found, nor that Society furnishes to men more real pleasures 
 than Nature affords to those who love her." 
 
INDEX. 
 
 A. 
 
 
 
 rage 
 
 
 Page 
 
 cuncata Ehr. 
 
 - 408 
 
 AcuNANTiiBS Bory 
 
 - 401 
 
 elongata Ehr. 
 
 - ib. 
 
 cxilis ? Klitz. 
 
 - 402 
 
 floccosa Ehr. 
 
 - 405 
 
 mimUissima Klitz. 
 
 - 401 
 
 paradoxa Gmeliii - 
 
 - 410 
 
 Agardhia Gray 
 
 - 160 
 
 seriata Ehr. 
 
 - 405 
 
 Anabaina Bory 
 
 - 281 
 
 sigmoidea Nitzsck 
 
 - 436 
 
 constrida Ilass. 
 
 - 283 
 
 tabellaris Ehr. - 
 
 - 405 
 
 fios-aqucB Bory 
 
 - 282 
 
 ulna Nitzsch 
 
 - 433 
 
 impalpchralis ? Bory 
 
 - 283 
 
 vulgaris Ehr. 
 
 - 407 
 
 lichcniformis ? Bory 
 
 - 282 
 
 Bangia Lyngh. 
 
 - 298 
 
 ? spiralis T'homp. - 
 
 - 278 
 
 calojiliylla Carm. - 
 
 - ib. 
 
 Anacystis Me legh. 
 
 - 319 
 
 fiisco pu7-purea Lyng. 
 
 - 440 
 
 furfuracca .\Icnegb. 
 
 - a. 
 
 maniillosa Lyng. 
 
 - 228 
 
 Anhaltia ScJiivcu''! 
 
 - 124 
 
 BATRACnOSPERME..E 
 
 - 101 
 
 Aphanizomenon Morren 
 
 - 27,9 
 
 Batrachospermu.m lioth. 
 
 - ib. 
 
 incurviim IMorreii 
 
 - 280 
 
 alpestre Shut. 
 
 - Ill 
 
 Aplonema Hnss. 
 
 - 213 
 
 atrum Harv. 
 
 - 114 
 
 Ajjona Adans - 
 
 - 68 
 
 hombusinum Bory 
 
 - 103 
 
 Aethrodesmus Eln: - 
 
 - 256 
 
 covfnsuni Hass. 
 
 - 105 
 
 acutus Eh'. 
 
 - 394 
 
 fasciculatum Vauch. 
 
 - 125 
 
 convergens Elir, - 
 
 - 357 
 
 glomeratum D. C. 
 
 - 120 
 
 Incus Hass. 
 
 - ib. 
 
 helmintositm Bory - 
 
 - 105 
 
 octocornis Ehr. 
 
 - ib. 
 
 hispidum 
 
 - 65 
 
 quadricaudatus Ehr. 
 
 - 392 
 
 intricatum Vauch. 
 
 - 127 
 
 Artiironema ITass. 
 
 - 238 
 
 ludibundum 
 
 - 106 
 
 cirrhosum Hass. - 
 
 - ib. 
 
 moniliforme Ag. - 
 
 - 108 
 
 Aulacoctstis Hass. - 
 
 - 437 
 
 myosurus Ducluz. 
 
 - 302 
 
 jyellucida Hass. 
 
 - ib. 
 
 plumosum Vauch. - 
 
 - 121 
 
 
 
 prolifcrum Hass. - 
 
 - 112 
 
 
 
 pulchern'mnm Hass. 
 
 - 109 
 
 B. 
 
 
 rubruin Hass. 
 
 - 113 
 
 
 
 dagnale Hass. 
 
 - 107 
 
 Bacillabia Ehr. 
 
 - 410 
 
 turfoaum Bory 
 
 - 110 
 
 communis B(»\)/ - 
 
 - 433 
 
 vagum Ag. 
 
 - 109 
 
450 
 
 INDEX. 
 
 
 
 Binatella Breh. 8^ Godey 
 
 Page 
 - 351 
 
 Hedwigii 
 
 _ 
 
 Page 
 
 - 97 
 
 m\xr\cat& Breb . 
 
 - ib. 
 
 hispida 
 
 - 
 
 - 99 
 
 tricornis Brch. 
 
 - 352 
 
 latifolia - 
 
 - 
 
 ■ - ib. 
 
 BoTRTDiNA Breh. 
 
 - 319 
 
 nidifica Ag. 
 
 - 
 
 - 95 
 
 vulgaris Breb. 
 
 - 320 
 
 pidchella - 
 
 - 
 
 - 97 
 
 BOTRYDIUM Wall. 
 
 - 305 
 
 translucens Ag. 
 
 - 
 
 - 94 
 
 granulatum Grev. 
 
 - ib. 
 
 vulgaris - 
 
 - 
 
 - 96 
 
 BuLBOCHiETE Ag. 
 
 - 209 
 
 Charospermum Link 
 
 - 
 
 - 118 
 
 setigera Ag. 
 
 - 210 
 
 Chlorococcum Grev. 
 
 - 
 
 - 323 
 
 
 
 murorum Grev. 
 
 . 
 
 - ib. 
 
 
 
 vulgare Grev. 
 
 - 
 
 - 333 
 
 C. 
 
 
 Choaspis Gray 
 
 - 
 
 - 135 
 
 
 
 Chthonoplastus Ki'dz. 
 
 - 
 
 - 260 
 
 Cadmus 
 
 - 193 
 
 CLADOPHORE^J 
 
 - 
 
 - 213 
 
 CALLITHAMNIEiE 
 
 - 75 
 
 Cladophora Kutz. 
 
 - 
 
 28. 213 
 
 Caxlithamnion 
 
 - ib. 
 
 (Bruginosa - 
 
 - 
 
 - 224 
 
 Daviesii - 
 
 - ib. 
 
 albida 
 
 - 
 
 - ib. 
 
 CALOTHRICE.E - 
 
 - 239 
 
 arcia 
 
 _ 
 
 - ib. 
 
 Calotheix Ag. 
 
 - ib. 
 
 crispata - 
 
 - 
 
 - 216 
 
 atroviridis Hai'V. - 
 
 - 243 
 
 diffusa 
 
 - 
 
 - 224 
 
 Berkeleyana Carm. 
 
 - 241 
 
 Jlexuosa - 
 
 - 
 
 - ib. 
 
 distorta Ag. 
 
 - 240 
 
 glauccscens 
 
 - 
 
 - ib. 
 
 interr jpta Cai^m. - 
 
 - 230 
 
 glomerata 
 
 - 
 
 - 213 
 
 lucifu.Ta Carm. 
 
 - 259 
 
 gracilis 
 
 - 
 
 - 224 
 
 mirah lis Ag. 
 
 - 243 
 
 Hutchinsice 
 
 - 
 
 - ib. 
 
 nivca Ag. - 
 
 - 241 
 
 latcvirens - 
 
 - 
 
 - ib. 
 
 rufescens Carm. - 
 
 - 242 
 
 lanosa 
 
 - 
 
 - ib. 
 
 Ceramium 
 
 - 57 
 
 nuda 
 
 - 
 
 - ib. 
 
 Cffispitosura Both. - 
 
 - ib. 
 
 pellucida - 
 
 - 
 
 - ib. 
 
 CH^TOPHORE^ - 
 
 - 116 
 
 rectangidaris 
 
 - 
 
 - ib. 
 
 Chzetophora Schrank - 
 
 - 124 
 
 refrada 
 
 - 
 
 - ib. 
 
 dilatata Hass. 
 
 - 125 
 
 riparia 
 
 - 
 
 - ib. 
 
 elegam Ag. 
 
 - 127 
 
 rupestris - 
 
 - 
 
 ' ib. 
 
 endivicEfolia Ag. - ' 
 
 - 125 
 
 uncialis 
 
 - 
 
 - ib. 
 
 longceva Carm. 
 
 - 128 
 
 Closterium Nitzsch. 
 
 32. 
 
 338. 367 
 
 pisiformis Ag. 
 
 - ib. 
 
 acerosiim Ehr. 
 
 - 
 
 - 374 
 
 tubercnlosa Hook. - 
 
 - 126 
 
 Brebissoni Menegh. 
 
 - 377 
 
 Chantransia D. C. 
 
 - 71 
 
 caudatum Corda 
 
 . 
 
 - 373 
 
 fluviatilis D. C. - 
 
 - 72 
 
 Cornu Ehr. 
 
 - 
 
 - 372 
 
 torulosa D. C. 
 
 - 71 
 
 costatuin Corda 
 
 - 
 
 - lb. 
 
 CIIAIIACE3} 
 
 - 77 
 
 cylindrus Ehr. 
 
 - 
 
 - 368 
 
 Chaka Ag. 
 
 - 96 
 
 Diance Ehr. 
 
 - 
 
 - 371 
 
 aspera 
 
 - 98 
 
 Digitus Ehr. 
 
 - 
 
 - 376 
 
 batrachosperma - 
 
 - 107 
 
 Ehrenbergii Menegh. 
 
 - 369 
 
 flexilis Ag. 
 
 - 95 
 
 grauuLatum Brel 
 
 
 - 378 
 
 gracilis Ag. 
 
 - 96 
 
 lineatum Ehr. 
 
 - 
 
 - 372 
 
INDEX. 
 
 451 
 
 Lunula Elir. 
 
 margaritaceum Ehr, 
 
 monilifcrum 
 
 multistriatum Ehr. 
 
 rostratum Ehr. 
 
 ruficeps Ehr. 
 
 sctaceum Ebr. 
 
 spirale Corda 
 
 striolatum Ehr. 
 
 tenuc Kidz. 
 
 Trahecula Ehr. 
 
 turgiduni Ehr. 
 CoccocHLORis Sprcng. 
 
 cystifera Ilass. 
 
 depresm INIenegh. - 
 
 Grevillei Ilass. 
 
 hyalina ^Menegli. - 
 
 Moorcana Hass. 
 
 mxiscicola Menegh. 
 
 ohscura Hass. 
 
 prohdjerans Menegh. 
 
 rhndaris Hass. 
 
 variabilis Hass. 
 CoccoNEMA Ehr. 
 
 cistida Ehr. 
 
 cymbiforme Ehr. - 
 
 gibbum Ehr. 
 
 lanceolatum Ehr. - 
 
 ventricosum Hass. - 
 Codium 
 
 CoLEOCILfflTE -B?*e&. 
 
 scutata Breb. 
 Conferva vlg-. 
 
 aegagropila Zni?i. - 
 alpiua Ag. 
 amphibia - 
 atra E. B. 
 atrovirens Dillw. - 
 bicolor E. B. 
 bombycina Ag. 
 Brownii Ag. 
 cocrulescens E.B. 
 cbalybea Iloih. 
 corymbifcra E.B. 
 crispata J?.J5. 
 dichotoma 
 
 P.ige 
 
 374 
 376 
 370 
 375 
 373 
 371 
 373 
 372 
 371 
 373 
 375 
 371 
 311 
 441 
 316 
 318 
 
 . 315 
 316 
 314 
 
 . 442 
 312 
 
 . 317 
 
 ■ 441 
 . 425 
 . 426 
 . ih. 
 
 ■ 427 
 
 ■ 426 
 
 ■ 427 
 
 • 47 
 
 • 217 
 
 • ib. 
 
 ■ 213 
 
 ■ 174 
 
 - 57 
 
 - 114 
 
 - 228 
 
 ■ 221 
 
 - 208 
 . 213 
 
 - 177 
 
 - 75 
 
 - ib. 
 
 - 216 
 
 - 51 
 
 dissiliens Dillw. - 
 dissiliens Ag. 
 dissiliens E. B. - 
 distorta Dilhc. 
 ericetorum Roth. - 
 flavcscens Harv. - 
 flexuosa - - - 
 
 flocculosa Dillw. - 
 fluviatilis lloth. 
 fracta Roth. 
 
 frigida - - " 
 
 fugacissima Dillw. 
 furcata - - - 
 
 fusco purpurea Dillw. 
 gelatinosa - - - 
 
 genuflexa Dillw. • 
 glomerata- - 31. 35 
 
 hispida Thore 
 jugalis M'nller 
 lineata Dillw. 
 lubrica 
 lucens Dilbo. 
 niirabilis Dillw. - 
 mucosa Mert. 
 multicapsularis Dillw. 
 muralis Dillw. 
 mutabilis Roth. 
 myochrous Dillw. - 
 nana Dillw: 
 nigricans Roth. 
 nitida Dillw. 
 nivea Dillw. 
 nodosa var. Lam. - 
 occUata Dillw. 
 ochracea Dillw. 
 ovata Ilopkirk 
 pectin alis Dillw. - 
 pisum Flor. Dan. - 
 porticalis Midler - 
 protensa Dillw. - 
 pulvinata Broicnii MSS. • 
 punctalis Dillw. - 
 purpuraseens Carm. 
 reticulata - 
 rivularis - 
 stritica 
 
 G G 2 
 
 PaRe 
 
 32 
 
 202 
 
 346 
 
 240 
 
 216 
 
 ib. 
 
 G5 
 
 405 
 
 73 
 
 216 
 
 52 
 
 223 
 
 57 
 
 440 
 
 106 
 
 173 
 
 .213 
 
 65 
 
 141 
 
 399 
 
 121 
 
 221 
 
 237 
 
 347 
 
 305 
 
 221 
 
 120 
 
 237 
 
 124 
 
 216 
 
 141 
 
 241 
 
 71 
 
 . 231 
 
 • 400 
 . 427 
 . 413 
 
 • 290 
 
 ■ 145 
 
 • 123 
 . 213 
 
 ■ 223 
 
 ■ 175 
 
 - 225 
 
 ■ 39 
 
 - 143 
 
452 
 
 INDEX. 
 
 Page 
 
 torulosa £".5. - - 71 
 
 torulosa var. Roth - ih. 
 
 tumidula - - 207 
 
 vaginata E. B. - - 260 
 
 verrucosa lyrap. - - 74 
 
 vesicata Z)i7^u>. - - 54 
 
 CON JUGATE J2 - - 129 
 
 Conjugata Vauch. 
 
 inflata Vauch. - - 151 
 
 longata Vauch. - - ib. 
 
 porticalis Vauch. - - 145 
 
 princeps Vauch. - - 141 
 
 CosMARiuM Cor da - - 361 
 
 aculeatutn Menegh. - 360 
 
 • angulosum Ehr. - - 363 
 
 binale Menegh. - - 384 
 
 Botrytis Menegh. - - 363 
 
 crenatum Ralfs - - 365 
 
 Cucumis Corda - - 366 
 
 Cucurbita Breb. - - 367 
 
 cylindricum Ralfs - - 365 
 
 deltoides Cordu - - 363 
 
 dentiferum Corda - - 362 
 
 Didelta Corda - - 381 
 
 gemmatum Breb. - - 382 
 
 lagenarlum Corda- - 381 
 
 margaritiferum - - 362 
 
 orhiculatum Ralfs - - 364 
 
 oblongum Menegh. - 380 
 
 ornatum Ralfs - - 364 
 
 oraZe Ralfs - - 366 
 
 Feha 3fe?ieg7i. - - 381 
 
 quadratum Ralfs - - 367 
 
 stellinum Corda - - 385 
 
 truncatum Corda - - ib. 
 
 verrucosum 3fenegh. - 380 
 
 Cruciagenia - - - 31 
 
 Gylinbrocystis Breb. - 361 
 
 Brcbissoni Menegh. - ib. 
 
 Cymbella Hass. - - 427 
 
 appendlculata Breb. - 430 
 avenacea Breb. Sf Godey - ib. 
 
 ? ^rcMS.Hass. - - 429 
 
 copulata Breb. - - ib. 
 
 Hopkirkii Moore - - 427 
 
 reniformis Ag. - - 362 
 
 sigmoidea Ag. 
 turgida Hass. 
 ventricosa Ag ? 
 zebra Hass. 
 CYSTOSPER]\IEiE - 
 
 Page 
 
 - 436 
 
 - 428 
 
 - 427 
 
 - 428 
 
 - 180 
 
 Dematium Link 
 
 - 232 
 
 turfaceura 
 
 " ib. 
 
 DESMIDEiE 
 
 - 30. 338 
 
 Desmidium Ag. 
 
 - 34. 341 
 
 aculeatum Ehr. - 
 
 - 353 
 
 apiculosum Ehr. - 
 
 - 351 
 
 bifidum Ehr. 
 
 - 355 
 
 bimucronatum Hass. 
 
 - 347 
 
 Borreri Ralfs 
 
 - 343 
 
 compressum Balfs 
 
 - 348 
 
 cylindricum Grev. - 
 
 - 342 
 
 hexaceros Ehr. - 
 
 - 354 
 
 mucosum Breb. - 
 
 - 346 
 
 orblculare Ehr. - 
 
 - 349 
 
 quadrangulatum Ralfs 
 
 - 345 
 
 Swartzii Ag. 
 
 - 344 
 
 vertebratum Breb. ^' 
 
 Go- 
 
 dey 
 
 348. 345 
 
 DIAT0MACEJ3 
 
 - 395 
 
 DiATOMA Ag. - 
 
 - 406 
 
 $ cuneatum 
 
 - 408 
 
 elongatum Ag. 
 
 - ib. 
 
 fenestratiim Lyngb. 
 
 - 406 
 
 flocculosum Balfs 
 
 - 405 
 
 flocculosum Ag. - 
 
 - 407 
 
 sulphurascens Ag. 
 
 - 408 
 
 tenue Ag. 
 
 - ib. 
 
 normale Kiltz. 
 
 - ib. 
 
 /3 cuneatum 
 
 - ib. 
 
 virescens Hass. 
 
 - 409 
 
 vulgar e Bory 
 
 - 407 
 
 Didymoprium Kiltz. - 
 
 - 342 
 
 Borrei'i Jen. 
 
 - 343 
 
 Grevillei Kiltz. 
 
 - 342 
 
 Draparnaldia Bory ,- 
 
 - 118 
 
 condensata Hass. - 
 
 - 122 
 
 elongata Hass. 
 
 - 123 
 
453 
 
 glomerata 
 hypnosa Bory 
 mutabilis Bory 
 nana Ilass. 
 plumosa Ag. 
 repetita Hass* 
 sparsa Hass. 
 tenuis Ag. 
 
 E. 
 
 Ecbinella Grcv. 
 
 circularis Gi-eii. - 
 
 fascicula Grev. 
 
 /3 truncata 
 
 oblongata Grev. - 
 
 rotata Grev. 
 EcTosPERMA Vauch. - 
 
 clavata Vauch. 
 
 geminata Vauch. - 
 
 hamata Vauch. 
 
 ovoidea Vauch. 
 
 racemosa Vauch. - 
 
 sessilis Vauch. 
 
 terrestris Vauch. - 
 Encyonema Kiltz. 
 
 jirostratum Kiitz. - 
 
 pai-adoxum Kiitz. 
 Enterojiorpua Linh - 
 
 intestinalis Link. - 
 
 lacustris Hass. 
 EuASTKUM Ehr. 
 
 affine llalfs 
 
 ansatum Ehr. 
 
 hinale Ralfs 
 
 circulare Ilass. 
 
 Didclta Ralfs 
 
 gcmmalum Ralfs - 
 
 integerrimum Ehr. 
 
 margaritiferum Ehr. 
 
 ohlongum Ralfs 
 
 pecten Ehr. 
 
 Pclta Ralfs 
 
 pentangulare Corda 
 
 rostratum Ralfs 
 
 117. 
 
 Page 
 7. 120 
 
 Rota Ehr. 
 
 . 
 
 Page 
 - 385 
 
 - 121 
 
 spinosum Ralfs 
 
 . 
 
 - 384 
 
 - 120 
 
 verrucosum Ebr. 
 
 - 
 
 - 379 
 
 - 124 
 
 EuNOTiA Ehr. 
 
 . 
 
 . 416 
 
 - 121 
 
 Arcus Ehr. 
 
 - 
 
 - ih. 
 
 - 122 
 
 Diodun Ehr. 
 
 - 
 
 - ib. 
 
 - 124 
 
 - 123 
 
 IMonodon l{ulfs 
 Tctraodon Elir. 
 
 - 
 
 - ib. 
 
 - ib. 
 
 
 Triodon Ehr. 
 
 - 
 
 . 428 
 
 
 turgidum Ehr. 
 
 - 
 
 - ib. 
 
 
 zebra Ehr. 
 
 . 
 
 - ib. 
 
 
 Eutomia Ilarv. 
 
 - 
 
 - 380 
 
 - 418 
 
 oblonga Ilarv. 
 
 - 
 
 - ib. 
 
 - ih. 
 
 rotata Harv. 
 
 _ 
 
 - 385 
 
 - 433 
 
 Exilaria Grev. 
 
 - 
 
 - 432 
 
 - ih. 
 
 - 380 
 
 capitata - 
 circularis Grev. 
 
 - 
 
 - 433 
 
 - 418 
 
 - 385 
 
 - 47 
 35.60 
 
 fasciculata Grev. 
 fasciculata Kiitz. 
 lunaris 
 
 ; 
 
 - 433 
 
 - 434 
 
 - ib. 
 
 - 55 
 
 minutissima Grev. 
 
 . 244 
 
 - 53 
 
 - 57 
 
 truncata Kiitz. 
 Ulna 
 
 - 
 
 - 433 
 
 - ib. 
 
 - 56 
 
 
 
 
 - 55 
 
 F. 
 
 
 
 - 53 
 
 
 
 
 - 439 
 
 Fragilaria - 
 
 - 
 
 33.412 
 
 - ib. 
 
 - ib. 
 
 - 303 
 
 angusta Ehr. 
 bipunctata Ehr. 
 confervoides Grev. 
 
 - 415 
 
 - ib. 
 
 - 414 
 
 - ib. 
 
 - ib. 
 
 - 379 
 
 - 382 
 
 - 381 
 
 - 384 
 
 diopthahna Ehi'. 
 grandis Ehr. 
 hycmalis Lyngb. 
 pccfinalis Lyngb. 
 pectinalis Ehr. 
 rhabdosoma Ehr. 
 
 - 
 
 - 415 
 
 - 413 
 
 - 414 
 
 - 412 
 
 - 409 
 
 - 415 
 
 - 383 
 
 scalaris Ehr. 
 
 _ 
 
 - 415 
 
 - 381 
 
 turgida Ehr. 
 
 . 
 
 - 414 
 
 - 382 
 
 - 366 
 
 - 362 
 
 (3 undulata 
 virescens Ifal/s 
 Frustulia Kiitz. 
 
 - 
 
 - 413 
 
 - 409 
 
 - 437 
 
 - 380 
 
 - ib. 
 
 cynibiforniis Kiit 
 gibba Ehr. 
 
 z. 
 
 - 42G 
 
 - 432 
 
 - ib. 
 
 gracilis Jcnncr 
 
 - 
 
 - 430 
 
 - 389 
 
 - 383 
 
 Hippocampus Jcnner 
 lanceolata Kiilz. - 
 
 G Q 3 
 
 - 435 
 
 - 432 
 
454 
 
 librilis Jcnner 
 nodosa Jcnner 
 Nitzschii Kiltz. 
 pellucida Kiltz. 
 sigmoidea Jenner 
 Ulna Ag. 
 ? viridi& Elir. 
 
 G. 
 
 Gall ion ell a Ehr. 
 
 aurichalcea Ehr. - 
 
 ferruginea Ehr. - 
 
 varians Ehr. 
 Gl^oprum Berk. 
 
 dissilieiis Berk. 
 
 mucostim Berk. 
 Globulina Liiik. 
 
 GOMPHONEMA Ag. 
 
 acuminatum Ehr. 
 
 ampullaceum Grev. 
 
 angustum Ag. 
 
 Berheleyi Grev. - 
 
 capitatum Ehr. 
 
 cristatum Ralfs 
 
 curvatum Kiltz. - 
 
 dichotomum Klitz. - 
 
 geminatum Ag. 
 
 gracile Ehr. 
 
 lanceolatum Ag. - 
 
 Leiblini Kiitz. 
 
 minutum Ag. 
 
 minutissimum Ag. 
 
 oculatum Kiitz. 
 
 pohliaeforme Kiitz. 
 
 subramosuni Kiitz. 
 
 truncatum Ehr. 
 Gongoseira Kiltz. ■ 
 
 clavata Kiitz. 
 Gongycladon Link 
 GoNiocTSTis Hass. 
 Gtbosigma Hass. 
 
 Hippocainpa Hass. 
 Gonlutu Ehr. 
 
 tranquillum 
 
 Page 
 436 
 431 
 436 
 437 
 "436 
 433 
 437 
 
 399 
 400 
 399 
 346 
 
 ib. 
 347 
 160 
 420 
 422 
 420 
 423 
 
 ib. 
 421 
 423 
 424 
 423 
 420 
 423 
 426 
 424 
 422 
 424 
 425 
 421 
 
 ib. 
 
 ib. 
 305 
 
 ib. 
 
 68 
 349 
 435 
 
 ib. 
 
 300 
 
 
 Page 
 
 H^MATOCOCCUS Ag. - 
 
 - 321 
 
 ■ceruginosus Hass. - 
 
 - 333 
 
 Allmani Hass. 
 
 - 322 
 
 alpestris Hass, 
 
 - 328 
 
 arenarius Hass. 
 
 - 330 
 
 binalis Hass. 
 
 - 331 
 
 cryptophilv^ Hass. 
 
 - 324 
 
 frustulosus Harv. - 
 
 - 330 
 
 furfuraceus Hass. - 
 
 - 331 
 
 granosus Harv. 
 
 - 327 
 
 Hookerianus Berk, and Hass. 325 
 
 insignis Hass. 
 
 - 324 
 
 lividus Hass. 
 
 - 332 
 
 .microspoi'us Hass. 
 
 - 334 
 
 minutissimus Hass. 
 
 - ib. 
 
 viu7'orum Hass. 
 
 - 323 
 
 rupestris Hass. 
 
 - 326 
 
 sanguiiieus Ag. 
 
 - 329 
 
 theriacus Hass. 
 
 - 333 
 
 vulgaris. Hass. 
 
 - ib. 
 
 Hassallia Berk. 
 
 - 231 
 
 ? byssoidea Hass. 
 
 - 233 
 
 compacta Ha,ss. 
 
 - 232 
 
 limbata II0.SS. 
 
 - 234 
 
 ocellata Berk, 
 
 - 231 
 
 turfosa Hass. 
 
 - 232 
 
 Hellerella Turp. 
 
 - 389 
 
 Boryana Turp. - 
 
 - ib. 
 
 Hempelia Meyen 
 
 - 187 
 
 mirabilis Meycn - 
 
 - 188 
 
 poljmorpha Meyen 
 
 - 190 
 
 Heterocarpella Bory - 
 
 - 363 
 
 binalls Turp. 
 
 - 384 
 
 Botrytis Bory 
 
 - 363 
 
 didelta Turp. 
 
 - 381 
 
 polymorpha Kiltz. 
 
 - ib. 
 
 tetracarpa Bory - 
 
 - 388 
 
 ursinella Kiitz. 
 
 - 363 
 
 HYDRODICTYONE.E 
 
 - 225 
 
 Hydeodictvon Both. - 
 
 - ib. 
 
 pentagoniim Vouch. 
 
 - ib. 
 
 utriculatum Roth. - 
 
 - ib. 
 
 H01.0CYSTIS Hass. 
 
 - 386 
 
 oscitans Hass. 
 
 - 387 
 

 INDEX. 
 
 456 
 
 
 Page 
 
 
 Page 
 
 Hydkurus Ag. 
 
 - 302 
 
 mirichalcea KUtz. - 
 
 - 399 
 
 Ducluzelii Ag. 
 
 - ib. 
 
 lineata Ag. 
 
 - ib. 
 
 
 
 ochracea Ralfs 
 
 - 340 
 
 
 
 Thompsoni Harv. 
 
 - 222 
 
 I. 
 
 
 varians Ag. 
 
 - 399 
 
 
 
 Meridion Lciblein 
 
 - 417 
 
 Isogonium Ki'dz. 
 
 - 195 
 
 circidare Ag. 
 
 - 418 
 
 capillare Ki'dz. 
 
 - ih. 
 
 constrictmn Ralfs - 
 
 - 419 
 
 
 
 vernale Ag. 
 
 - 424 
 
 
 
 IklERISMOPEDIA McyCU 
 
 - 299 
 
 L. 
 
 
 punctata INIeyen - 
 
 - ib. 
 
 
 
 Mesocarpus Hass. 
 
 22. 166 
 
 Leda Bory 
 
 - 178 
 
 a7)gustus Hass. 
 
 - 170 
 
 capucina Bory 
 
 - ih. 
 
 dcprcssus Hass. 
 
 - 168 
 
 LEMANE/E - 
 
 - G8 
 
 intricatus Hass. 
 
 - 167 
 
 Lemania Bory 
 
 35. G8 
 
 notabilis Hass. 
 
 132. 170 
 
 corallina Bory 
 
 - 72 
 
 mammdoidcs Hass. 
 
 - 169 
 
 Jluviatilis Ag. 
 
 - ib. 
 
 ovalis Hass. 
 
 - ib. 
 
 incurvata Bory 
 
 - 71 
 
 parvulus Hass. 
 
 - ib. 
 
 toridosa Ag. 
 
 - ib. 
 
 recu7-vus Hass. 
 
 - 168 
 
 Lichen 
 
 - 228 
 
 scalaris Hass. 
 
 - 166 
 
 pubescens E. B. - 
 
 - ib. 
 
 MiCRASTERIAS Efl?: 
 
 - 385 
 
 LiTUONEMA IlaSS. 
 
 - 265 
 
 angulosa BJir. 
 
 - 391 
 
 calcareum Hass. - 
 
 - ib. 
 
 Boryana Ehr. 
 
 - 389 
 
 crustaceum Hass. - 
 
 - 266 
 
 Boryi Kidz. 
 
 - ib. 
 
 Luceruaria Rotiss. 
 
 - 160 
 
 duplex Ki'dz. 
 
 - ib. 
 
 Lunuliua Turp. 
 
 - 370 
 
 elliptica Ehr. See 
 
 riale 
 
 vulgaris Ttvp. 
 
 - ib. 
 
 XCn. Fig. 2. 
 
 
 monilifera Bory - 
 
 - ib. 
 
 • heptactis Ehr. See Plate 
 
 Lyngbya Ag. 
 
 33. 219 
 
 XCH. Fig. 9. 
 
 
 copidata Ilass. 
 
 - 222 
 
 hcxactis Ehr. See Tlate 
 
 floccom Hass. 
 
 - 223 
 
 XCn. Fig. 5. 
 
 
 fusco-purpurea Ilass. 
 
 - 440 
 
 melitensis Ralfs - 
 
 - 386 
 
 vmralis Ag. 
 
 - 221 
 
 ? oscitans Ralfs - 
 
 - 387 
 
 prolijica Grev. 
 
 - 224 
 
 radiata Hass. 
 
 - 386 
 
 p^mdalis Ilass. 
 
 - 223 
 
 rota Mcnegh. 
 
 - 3S5 
 
 Thompsoni Hass. - 
 
 - 222 
 
 rotata Ag. 
 
 - ib. 
 
 vermicularis Hass. 
 
 - 224 
 
 Selanffia Kidz. 
 
 ' 389 
 
 viresccns Hass. 
 
 - 222 
 
 simplex Ki'dz. 
 
 - ih. 
 
 zonata Hass. 
 
 - 220 
 
 Staurastrum Ki'dz. 
 
 - 354 
 
 
 
 tetracera Ki'dz. 
 
 - ih. 
 
 
 
 tetras Ehr. 
 
 - 388 
 
 M. 
 
 
 tricera Kidz. 
 
 - 354 
 
 
 
 tricyclia Ehr. 
 
 - 391 
 
 Meloseira Ag. 
 
 33. 396 
 
 ]\IicRocoLEi!S Besmar. 
 
 - 260 
 
 arenosa ^loore 
 
 - 398 
 
 anguiformis Harv. 
 
 G G 4 
 
 - 261 
 
456 
 
 JNDEX. 
 
 
 
 Page 
 
 
 Page 
 
 gracilis Hass. 
 
 - 261 
 
 librUis Ehr. 
 
 - 436 
 
 repens Harv. 
 
 - 260 
 
 nodosa Ehr. 
 
 - 431 
 
 Microcystis Menegli. - 
 
 - 321 
 
 Palea Hass. 
 
 - 430 
 
 granosa Menegli. - 
 
 - 328 
 
 ? pellucida ^Ar. - 
 
 - 437 
 
 livida Menegh. 
 
 - 332 
 
 phosnicenteron Ehr. 
 
 - 429 
 
 mellea ? Menegh. - 
 
 - 323 
 
 platystoma Ehr. 
 
 - 431 
 
 rupestris Menegh. 
 
 - 326 
 
 sigmoidea Ehr. 
 
 - 436 
 
 Microhaloa Kiltz, 
 
 - ih. 
 
 turgida Ehr. 
 
 - 428 
 
 rupestris 
 
 ' ib. 
 
 viridis Ehr. 
 
 - 437 
 
 Microspora Hass. 
 
 - 213 
 
 zebra Ehr. 
 
 - 428 
 
 crispata Hass. 
 
 - 216 
 
 NiTzscHiA Hass. 
 
 - 435 
 
 glomerata Hass. - 
 
 - 213 
 
 ehngata Hass. 
 
 - ih. 
 
 Monema Berk. 
 
 - 439 
 
 Nodularia Link. 
 
 - 68 
 
 prostratum 
 
 - ib. 
 
 NosToc Vauch. 
 
 - 286 
 
 MONOCYSTE^ - 
 
 - 212 
 
 ccerideum Ljngb. - 
 
 - 293 
 
 IMOUGEOTIA Ag. 
 
 22. 171 
 
 commune Vauch. - 
 
 - 288 
 
 genuflexa Ag. 
 
 - 178 
 
 crassisporum Menegh. 
 
 - 294 
 
 glutinosa Hass. - 
 
 - 177 
 
 foliaceum Ag. 
 
 - 289 
 
 major Hass. 
 
 - 172 
 
 intricatiim Menegh. 
 
 - 286 
 
 parvula Hass. 
 
 - 169 
 
 macrosporum ? Menegh 
 
 - 293 
 
 stritica 
 
 - 148 
 
 microscopicum Carm. 
 
 - 292 
 
 MoKORMiA Berk. 
 
 - 285 
 
 muscorum Ag. 
 
 - ib. 
 
 intricata Berk. 
 
 - 286 
 
 pruiniforme Ag. - 
 
 - 291 
 
 Myriodactjlon Desv. - 
 
 - 124 
 
 sphcericum Vauch. 
 
 - 289 
 
 Miilleria Schranh 
 
 - 369 
 
 variegatum Moore 
 
 - 287 
 
 Lunula Schranh - 
 
 - ib. 
 
 verrucosum Vauch. 
 
 - 291 
 
 
 
 vesicarium D. C. - 
 
 - 290 
 
 N. 
 
 
 NOSTOCHINE^ - 
 
 - 267 
 
 NiTEIXA Ag. - 
 
 - 94 
 
 0. 
 
 
 JJexilis Ag. 
 
 - 95 
 
 
 
 gracilis Ag. 
 
 - 96 
 
 Odontella-E^r. 
 
 
 nidijica Ag. 
 
 - 95 
 
 undentata 
 
 - 348 
 
 translucens Ag. 
 
 - 94 
 
 (Edogonium Link. 
 
 - 193 
 
 Navicula Bory 
 
 - 429 
 
 Opharium Losano 
 
 - 389 
 
 amphishcena Ehr. - 
 
 - 430 
 
 OSCILLATORLE 
 
 - 224 
 
 arcus Ehr. 
 
 - 429 
 
 OsciLLATOKiA Vauch. - 34. 
 
 39. 245 
 
 biceps? Bonj 
 
 - 437 
 
 cerugescens Drum. 
 
 - 249 
 
 ? bifrons Ehr. 
 
 - 438 
 
 ? alata Carm. 
 
 - 238 
 
 geminata ? Turp. - 
 
 - 427 
 
 amphibia Ag. 
 
 - 251 
 
 ? gihha Ebr. 
 
 - 432 
 
 aidumnalis Ag. 
 
 - ib. 
 
 g7-acilis Ebr. 
 
 - 430 
 
 Bangii 
 
 - 259 
 
 ■ Hippocampus Ehr. 
 
 - 435 
 
 Carmichaeli Hass. 
 
 - 256 
 
 incequalis Ehr. 
 
 - 431 
 
 chthoplastes j3 Harv. 
 
 - 260 
 
 lanceolata Ehr. 
 
 - 432 
 
 cinerea Hass. 
 
 - 247 
 
INDEX. 
 
 457 
 
 contexta Carm. 
 coi-ium Ag. 
 corticola Carm. BIS. 
 cyanea Kg. 
 decorticans 
 decorticans (3 
 Dicldei Hass. 
 elegans Ag. 
 Fricsii Ag. 
 limhata Grev. 
 limosa Ag. 
 limosa Hook. 
 limosa Grev. 
 lucifnga Ilarv. 
 membranacea Ag. 
 mucosa Hass. 
 miiscorum 
 nigra Vauch. 
 nigra Carm. 
 ochracea Grev. 
 pulchclla Hass. 
 repens Ag. 
 rubiginosa Carm. - 
 nipestris Ag. 
 spadicea Carm. 
 spiralis Carm. 
 splendida Gi-ev. - 
 suhfiisca Vaucb. - 
 tejiax Carm. ]\IS. - 
 tenuis Ag. 
 temdssima Ag. 
 tcrehrifo7-mis Ag. - 
 tJicrmalis Hass. 
 turfosa Carm. 
 violacea Johnst. - 
 virescens Hass. 
 viridis Johnst. 
 OcRACoccus Hass. 
 
 TALMELLE.^ 
 Pal.aiella Lyngh. 
 
 pcruginosa Carm. 
 
 alpicola Lyngb. 
 
 rage 
 
 
 rape 
 
 25G 
 
 botryoides Lyngb. - 
 
 - 318 
 
 252 
 
 botrjoidcs G?-ev. - 
 
 - ib. 
 
 257 
 
 criicnta Ag. 
 
 - 308 
 
 248 
 
 cryptophylla Carm. 
 
 - 324 
 
 257 
 
 dopressa Berli. 
 
 - 316 
 
 ib. 
 
 frustulosa Carm. - 
 
 - 330 
 
 258 
 
 furfuracca BerJc. - 
 
 - 331 
 
 251 
 
 grauosa Berk. 
 
 - 328 
 
 258 
 
 GrcviUei Berk. - 
 
 - 318 
 
 234 
 
 Grevillei ay 
 
 - ib. 
 
 246 
 
 grumosa Carm. - 
 
 - 311 
 
 248 
 
 hyalina Lyngb. 
 
 - 315 
 
 255 
 
 hyalina (3 musioola Harv. - 314 
 
 259 
 
 livida Carm. 
 
 - 332 
 
 250 
 
 niontana Ag. 
 
 - 309 
 
 247 
 
 IMooreana Harv. - 
 
 - 316 
 
 252 
 
 muscicola var. Harv 
 
 - 314 
 
 255 
 
 myosurus Lyngb. - 
 
 - 403 
 
 257 
 
 nivalis Hook. 
 
 • 335 
 
 40 
 
 profuberans Ag. - 
 
 - 312 
 
 250 
 
 Ralfsii Harv. 
 
 - 310 
 
 260 
 
 rivularis Ca?'m. 
 
 - 317 
 
 254 
 
 nipestris Lyngb. - 
 
 - 326 
 
 ib. 
 
 ? sanguinea Ag. - 
 
 - 329 
 
 255 
 
 Palmogloea Kiitz. 
 
 - 312 
 
 277 
 
 protuberans Kiitz. 
 
 - ib. 
 
 251 
 
 Pediastrum Meyen 
 
 - 387 
 
 253 
 
 angulosum Hass. - 
 
 - 391 
 
 254 
 
 biscidiatum Meyen 
 
 - 389 
 
 248 
 
 Boryanum Meneg. 
 
 - ib. 
 
 259 
 
 constridum Hass. - 
 
 - 391 
 
 257 
 
 crcbriformc Hass. - 
 
 - 392 
 
 250 
 
 duplex Meyen 
 
 - 389 
 
 253 
 
 clcgans Hass. 
 
 - ib. 
 
 254 
 
 elUpticum Hass. See Plate 
 
 250 
 
 XCII. Fig. 2. 
 
 
 248 
 
 heptactis Hass. Sec 
 
 Plate 
 
 322 
 
 XCU. Fig. 9. 
 
 
 
 hexactis Hass. See 
 
 Plate 
 
 
 XCif Fig. 5. 
 
 
 
 lunare Hass. See 
 
 Plate 
 
 
 XCn. Fig. 3. 
 
 
 306 
 
 Napoleonis Balfs - 
 
 - 389 
 
 ib. 
 
 Napoleonis Hass. See Plate 
 
 333 
 
 xcn Figs. 10, 11. 
 
 
 309 
 
 quadrangum Corda 
 
 - 389 
 
458 
 
 Rotula Hass. See 
 XCII. Fig. 7. 
 
 simplex Hass. 
 
 simplex Meyen 
 
 tetras Ralfs 
 
 tricyclium Hass. 
 Pentasterias Ehr. 
 
 araclmis Hass. 
 
 Jenneri Hass. 
 
 margaritaceum Ehr. 
 Petalonema J3e?'A. 
 
 alatum Berk. 
 Phormidium /i^wte. 
 Pleurococcus Menegh. 
 
 glomeratus ? Menegh. 
 
 murorum Menegh. 
 
 thermalis Menegh. 
 
 vulgaris Menegh. - 
 
 PODOSPHENIA Eh7\ 
 
 ? oculatiim Hass. - 
 
 Polycoma Vals. 
 
 Poljsperma Vauch. 
 
 fiuviatilis Vauch. - 
 
 Prasiola Ki'dz. 
 
 Prolifera Vauch. 
 
 Borissii Le Clerc - 
 Boscii Le Clerc - 
 Candollii Le Clerc 
 composita Le Clerc 
 Cuvieri Le Clerc - 
 rivularis Le Clerc 
 Rothii Le Clerc - 
 Vauchei-ii Le Clerc 
 
 Protococcus Ag. 
 nivalis Ag. 
 
 R. 
 
 Kaphidia Carm. 
 
 angnlosa Hass. 
 
 vi7-idis Hass. 
 
 natans Carm. 
 RivuLARiA Roth. 
 
 angulosa Roth. 
 
 botryoides Ag. 
 
 crustaceum Carm. 
 
 Page 
 
 Plate 
 
 - 388 
 
 - 389 
 
 - 388 
 
 - 390 
 
 - 355 
 
 - ih. 
 
 - 356 
 
 - ih. 
 
 - 237 
 
 - 238 
 
 - 246 
 
 - 328 
 
 - ib. 
 
 - 323 
 
 - 331 
 
 - 333 
 
 - 425 
 
 - ib. 
 
 - 64 
 
 - 73 
 
 - 295 
 15. 191 
 
 - 202 
 
 - 207 
 
 - 208 
 
 - 196 
 
 - 198 
 
 - 197 
 
 - 208 
 
 - 200 
 
 - 335 
 
 - ib 
 
 - 264 
 
 - ib. 
 
 - 265 
 
 - 264 
 
 - 262 
 
 - 264 
 
 - 263 
 
 - 266 
 
 Page 
 calcareum E. B. - - 265 
 
 granulifera Carm. - 263 
 
 pisum Ag. - - 262 
 
 tuberculosa E. B. - 126 
 
 EIVULAREuE - - 262 
 
 S. 
 
 Salinacis Bory - - 135 
 
 Scenedesmus Meyen - - 392 
 
 acutus Meyen - - 393 
 
 bijugatus Kiitz. - - ib. 
 
 bilunatus Kiltz. - - ib. 
 
 dimoiphus Kiitz. - - ib. 
 
 y ecornis - - 392 
 
 Leibleini Kiitz. - - 393 
 
 minor Kiitz. - - ib. 
 
 octalternus Kutz. - - 394 
 
 obtusus Menegh. - - ib. 
 
 pectinatus Meyen - ~ 393 
 
 quadralternus Kixtz. - 394 
 
 trijugatus KUdz. - - 393 
 triseriatiis. See Plate 
 
 XCII. Fig. 15. 
 
 quadricaudatus Breb. - 392 
 
 Schistochilum Ralfs - - 348 
 
 excavatum - - 349 
 
 unidentatum - - 348 
 
 Schizomena Ag. - - 439 
 
 ? prostratum ITarv. - ib. 
 
 SCYTONEME.E - - 227 
 
 Scytonema Ag. - - 235 
 a?rugIneo-cinereum Kiltz. - 234 
 
 Bangii - - . 259 
 
 byssoideum Ag. - - 233 
 
 cirrhosum Carm. - - 238 
 
 compactum Ag. - - 232 
 
 contextum Ca7'7n. - - 237 
 Dillwynii Harv. ^ Ralfs 242 
 
 Hibe7-nicum Hass. - - 236 
 
 minutum Ag. • - 230 
 
 myochrotis Ag. - - 237 
 
 ocellatum Lyngb. - - 231 
 
 panniforme Ca7-m. - 229 
 
 turfosum E.B. - - 232 
 
459 
 
 SIPHONEiE 
 
 Sirogonium Ki'ttz. 
 
 striticum - 
 Sirosyphon Kiltz. 
 SOKOSPORA Hass. 
 
 montana Hass. 
 
 Ralfsii Hass. 
 
 virescens Hass. 
 
 f grumosa Hass. - 
 Spliffii-ocarpus Hass. 
 Sphan-oplea Berk. 
 
 crispa Berli. 
 
 punctalls Berk. 
 Sph^rophora Hass. - 
 
 SPHiEROZYGA Ag. 
 
 Jacobi Ag. 
 Sph^tjrozosma Corda 
 
 elegans Corda 
 
 excavatum - 
 Spirillum Efi?: 
 
 Jenneri Hass. 
 
 minutissimum Hass. 
 
 rupestra Hass. 
 
 Thompsoni Hass. - 
 SPHYNCTOCrSTIS Huss. 
 
 librilis Hass. 
 Spirogyra Link 
 SuRiRELLA Turp. 
 
 bifrons Ehr. 
 
 hise7-iata Turp. 
 
 Jenneri Hass. 
 Staurastrum 
 
 aracbne lialfs 
 
 aculeatum Menegh. 
 
 ? hijidum llalfs 
 
 convergens Menegh. 
 
 dilatatum Ehr . 
 
 gracile Balfs 
 
 Incus Menegh. 
 
 Jenneri Balfs 
 
 luargaritaceuni 
 
 muricatum Menegh. 
 
 mucronatum Balfs 
 
 ? octocornis Balfs - 
 
 orbiculare Menegh. 
 
 pai-adoxum IMeyen 
 
 Page 
 
 ■ 47 
 . 143 
 . ib. 
 
 ■ 231 
 
 • 309 
 . ib. 
 . 310 
 
 • ib. 
 
 ■ ib. 
 
 ■ 166 
 
 ■ 219 
 
 ■ 221 
 
 - 223 
 
 - 396 
 
 - 283 
 
 - 284 
 
 - 348 
 
 - ib. 
 
 - 349 
 
 - 277 
 
 - ib. 
 
 - 278 
 
 - 277 
 
 - 278 
 
 - 436 
 
 - ib. 
 
 - 135 
 
 - 438 
 
 - ib. 
 . ib. 
 
 - 439 
 
 - 353 
 
 - 355 
 
 - 353 
 
 - 355 
 
 - 357 
 
 - 353 
 
 - 352 
 
 - 357 
 
 - 356 
 
 - ib. 
 
 - 351 
 
 - 350 
 
 - 358 
 
 - 349 
 
 - 354 
 
 paradoxum Ehr. - 
 ? tetraccrum llalfs 
 tricorne Menegh. - 
 Stauridium Coi-da 
 
 bicuspidatura Corda 
 crux melitensis 
 Staurocarpus 
 
 carulcscens Hass. - 
 capucinus Hass. 
 glutinosus Hass. 
 gracilis Hass. 
 gracillimus Hass. - 
 quadratus Hass. 
 virescens Hass. 
 Staurospermuiu Kiltz. - 
 Stellulina Link 
 Sigraatella Kiltz. 
 STIGONEME/E 
 Stigonema Ag. 
 atrovirens Ag. 
 intcrruptwn Hass. 
 mamillosum Ag. 
 minutum Hass. 
 pannifo7-me Harv. 
 Stygcocloniuin Kiltz. - 
 Stylaria 
 
 Synipbosyphon Kiltz. - 
 Syniploea Kiltz. 
 Synedra Ehr. - 
 capitata Ehr. 
 Ulna Ehr. 
 lunar is Ehr. 
 
 T. 
 
 Tabellaria Shut 
 fenestrata - 
 floccrdosa - 
 
 TetiMEmorus Balfs 
 Brcbissoni Rnlfs 
 gi-amdatiis llalfs 
 
 Tetractci.us Balfs 
 lacustris llalfs 
 
 Tetraspora Link 
 flava Hass. 
 
 Page 
 
 - 354 
 
 - ib. 
 
 - 352 
 
 - 388 
 
 - ib. 
 
 - ib. 
 22. 176 
 
 - 177 
 
 - ib. 
 
 - ib. 
 
 - 179 
 
 - ih. 
 
 - 178 
 
 - ib. 
 
 - 176 
 
 - 160 
 
 - 435 
 
 - 227 
 
 - ib. 
 
 - ih. 
 
 - 229 
 
 - 228 
 
 - 230 
 -^29 
 
 - 119 
 
 - 420 
 
 - 234 
 
 - 258 
 
 - 433 
 
 - ib. 
 
 - ib. 
 
 - 434 
 
 - 404 
 
 - 405 
 
 - 404 
 
 - 377 
 
 - ib. 
 
 - 378 
 
 - 402 
 
 - 403 
 
 - 300 
 
 - 301 
 
460 
 
 gelatinosa Desv. - 
 
 luhrica Ag. 
 THORE^ - 
 Thorea Bory - 
 
 Lelimanni 
 
 ramosissima 
 Tiresias Bory - 
 
 ToLYrOTHRIX Kutz. 
 
 Berkeleyana 
 
 Dillwynii Hass. 
 
 distoiia Kiitz. 
 
 iiivea Hass. 
 
 punctata Hass. 
 
 rvfescens Hass. 
 Tremella 
 
 cruenta E. B. 
 
 fluviatilis Dillw. - 
 
 granulata JE. B. - 
 
 nostoc E. B. 
 
 tei-restris E. B. - 
 Trentopohlia Ag. 
 
 pidchella Ag, 
 Trichodesmium Montague 
 
 Ehrenhergii Mtgne. 
 
 Hindsii Mtgne. 
 Tricliogonus 
 Trichormus Allm. 
 
 incurvus Allra. 
 Trigonocystis Hass. 
 
 ? acideata Hass. 
 
 bi/idus Hass. 
 
 gracUis Hass. 
 
 hexaceros Hass. 
 
 mucronata Hass. 
 
 muricata Hass. 
 
 var. rugosa 
 
 orbicularis Hass. - 
 Tyndarfdea Bory - 
 
 anomala Ralfs 
 
 bicornis Hass. 
 
 conspicua Hass. 
 
 cruciata Hass. 
 
 decussata - 
 
 lutescens Hass. 
 
 immersa Hass. 
 
 Page 
 
 
 Page 
 
 - 301 
 
 insignis Hass. 
 
 - 163 
 
 - 300 
 
 Ralfsii Hass. 
 
 - 165 
 
 - 64 
 
 stugnalis Hass. 
 
 - 163 
 
 - ib. 
 
 
 
 - 65 
 
 
 
 - ib. 
 
 
 
 - 193 
 
 U. 
 
 
 - 240 
 
 
 
 - 241 
 
 ULOTHRICE^ 
 
 - 119.219 
 
 - 242 
 
 Ulothrix Kiitz. 
 
 - 219 
 
 - 240 
 
 zonata 
 
 - ib. 
 
 - 241 
 
 ULVACEiE 
 
 ' 30. 225 
 
 - 240 
 
 Ulva Li7m. 
 
 - 296 
 
 - 242 
 
 binalis Hass. 
 
 - 299 
 
 - 288 
 
 bullosa Roth. 
 
 - 297 
 
 - 308 
 
 calopJiylla Spreng. 
 
 - 298 
 
 - 291 
 
 crispa Light. 
 
 - 297 
 
 - 305 
 
 furfiiracea Home. 
 
 - ib. 
 
 - 288 
 
 incrassata E. B. - 
 
 - 125 
 
 - ib. 
 
 montana - 
 
 - 309 
 
 - 75 
 
 protuberans Smith 
 
 - 312 
 
 - ib. 
 
 pisiformis Hudson 
 
 - 20 
 
 - 271 
 
 pruiniformis 
 
 - 291 
 
 - ib. 
 
 Uredo 
 
 
 - 275 
 
 nivalis Bauer 
 
 - 335 
 
 - 68 
 
 Ursinella Turp. 
 
 - 363 
 
 - 284 
 
 margaritifera Turp. 
 
 - ib. 
 
 - 285 
 
 
 
 - 349 
 
 
 
 - 353 
 
 
 
 - 355 
 
 V. 
 
 
 - 352 
 
 
 
 - ib. 
 
 Vaginaria Gray 
 
 - 260 
 
 - 350 
 
 vulgaris - 
 
 - ib. 
 
 - 351 
 
 Vaucheria D. C. - 15. 
 
 26. 33. 47 
 
 - ib. 
 
 aversa Hass. 
 
 - 54 
 
 - 349 
 
 clavata - 
 
 - 16. 59 
 
 22. 160 
 
 dichotoma Ag.'iv - 
 
 - 51 
 
 - 161 
 
 Dillwynii Ag. 
 
 - 52 
 
 - 162 
 
 geminata Vauch. - 
 
 - 55 
 
 - 164 
 
 hamata Hass. 
 
 - 53 
 
 - 160 
 
 ornithocepliala Ag. 
 
 - 54 
 
 - 165 
 
 ovoidea Vauch. 
 
 - 57 
 
 - 162 
 
 polysperma Hass. - 
 
 - 59 
 
 - 164 
 
 racc)7iosa Vauch. - 
 
 - 56 
 
461 
 
 repens Ilass. 
 
 - 
 
 - 52 
 
 X. 
 
 
 scssilis Vaucb, 
 
 . 
 
 - 55 
 
 
 r.ngo 
 
 terrcstris Vauch. 
 
 . 
 
 - 53 
 
 Xantuidium Ehr. 
 
 - 358 
 
 Ungeri Thuret 
 
 , 
 
 - GO 
 
 aculeatum Ehr, 
 
 - 360 
 
 Tertebrarla liouss. 
 
 - 
 
 - 68 
 
 (i deltoidcum Corda 
 
 - 351 
 
 rESICULIFERA 
 
 22. 25. 
 
 28. 195 
 
 fasciculatum Ehr. - 
 
 - 359 
 
 cequalis Ilass. 
 
 _ 
 
 - 205 
 
 furcatum Ehr. 
 
 - ib. 
 
 affinis Hass. 
 
 . 
 
 - 206 
 
 ft polygonum Ehr. 
 
 - 360 
 
 alata Hass. 
 
 - 
 
 - 208 
 
 polygonum Hass. - 
 
 - ih. 
 
 aurea Hass. 
 
 - 
 
 - 202 
 
 
 
 bombycina Hass. 
 
 - 
 
 - 208 
 
 
 
 Borissii Hass. 
 
 - 
 
 - 201 
 
 'Z. 
 
 
 Boscii Hass. 
 
 - 
 
 - 207 
 
 
 
 Candollii Hass. 
 
 - 
 
 - 208 
 
 Zoocarpa Nees of Escnh. 
 
 - 103 
 
 capillaris Hass. 
 
 - 
 
 - 195 
 
 Zoospores 
 
 - 11 
 
 cardiaca - 
 
 - 
 
 - 203 
 
 Zygnema Ag. - 5. to 10. 22. 28. 
 
 ciliata Hass. 
 
 - 
 
 - 202 
 
 
 130. 135 
 
 compressa Hass. 
 
 - 
 
 - 204 
 
 (Estivum Hass. 
 
 - 146 
 
 concatenata Hass. 
 
 - 
 
 - 201 
 
 ahhreviatum Hass. 
 
 - 154 
 
 condensata Hass. 
 
 - 
 
 - 196 
 
 affine Hass. 
 
 - 155 
 
 crossa Hass. 
 
 - 
 
 - ih. 
 
 alternatum Hass. - 
 
 - 139 
 
 cri's;)fl Hass. 
 
 - 
 
 - 203 
 
 angulare Hass. 
 
 - ib. 
 
 Cuvieri Hass. 
 
 - 
 
 - 198 
 
 belle Hass. 
 
 • 142 
 
 dissiliciis Hass. 
 
 - 
 
 - 202 
 
 catenaforme Hass. 
 
 - 147 
 
 ffejza Hass. 
 
 - 
 
 - 206 
 
 commune Hass. 
 
 - 148 
 
 elegans 7/a55. 
 
 - 
 
 - 207 
 
 curvatiim Ag. 
 
 - 143 
 
 faciata Hass. 
 
 - 
 
 - 204 
 
 deciminum Ag. 
 
 - 144 
 
 JIavesccns Hass. 
 
 - 
 
 - 206 
 
 didiictum Hass. 
 
 - 158 
 
 hexagona Hass. 
 
 - 
 
 - ih. 
 
 dubium Hass. 
 
 - 159 
 
 inaqualis Hass. 
 
 - 
 
 - 205 
 
 favcscens Hass. 
 
 - 149 
 
 lacustris Hass. 
 
 - 
 
 - 198 
 
 gracile Hass. 
 
 - 148 
 
 Landshoronglii Hass. 
 
 - 197 
 
 GrevUleaman Hass. 
 
 - 149 
 
 Mulleri Hass. 
 
 - 
 
 - 207 
 
 Hassallii Jenner - 
 
 - 156 
 
 ouoto Hass. 
 
 - 
 
 - 201 
 
 inceqnale Hass. 
 
 - 150 
 
 paludosa Hass. 
 
 - 
 
 - 199 
 
 injlatum Hass. 
 
 - 151 
 
 princeps Hass. 
 
 - 
 
 - 195 
 
 insigne Hass. 
 
 - 440 
 
 prolongata Hass. 
 
 
 - 198 
 
 intermedium Hass. 
 
 - 157 
 
 pulchclla Hass. 
 
 
 - 199 
 
 i7iterruphim Hass. 
 
 - 140 
 
 i?fl//5u Hass. 
 
 
 - ib. 
 
 Jcnneri Hass. 
 
 - 158 
 
 i2o<;(« Hass. 
 
 
 - 208 
 
 loiigatum Hass. 
 
 - 151 
 
 spharka Hass. 
 
 
 - 204 
 
 malformatum Hass. 
 
 - 147 
 
 Vaucherii Hass. 
 
 
 - 200 
 
 mallcolum Hass. 
 
 - 155 
 
 ventricosa JZass. 
 
 
 - ih. 
 
 maximum Hnss. - 
 
 - 139 
 
 virescens Hass. 
 
 
 - ih. 
 
 jnini?num Hass. 
 mirahile Hass. 
 
 - 159 
 132. 156 
 
462 
 
 neglectum Hass. 
 nitidum Hass. - 
 orbiculare Hass. 
 parvum Hass. 
 pellucidum Hass. 
 quadratum Hass. 
 quininum Ag. 
 revei'sum Hass. 
 rivulai'e Hass. 
 
 INDEX. 
 
 
 
 Page 
 - 142 
 
 
 rostratum Hass. 
 
 - '?J 
 
 29. 141 
 
 
 serratum Hass. 
 
 - 140 
 
 - 138 
 
 
 subventricostim Hass. 
 
 - 150 
 
 « 149 
 
 
 tenuissimum Hass. - 
 
 - 152 
 
 - 143 
 
 
 varians Hass. 
 
 - 145 
 
 - 157 
 
 
 vesicatum Hass. 
 
 - 158 
 
 - 145 
 
 
 TFboc?su Hass. 
 
 - 153 
 
 - 154 
 
 Zygogonium Kutz. 
 
 '. 173 
 
 - 144 
 
 
 ericetorum Kutz. - 
 
 - 174 
 
 END OF THE FIRST VOLUME. 
 
 toNDDN s 
 
 Printed by A. SpoTTiswoobBj 
 Ne wS treet- Square. 
 
ERBATA. 
 
 Page 124. 1 
 140. li 
 153.1 
 154.1 
 199.1 
 231,1 
 
 260. 1; 
 
 261. I 
 291. i: 
 394. 1 
 
 ne 2. for "Fig. 3." read "Fig. 4." 
 
 ne 6. from bottom/for "Plate XXIII." read " Plate XVIIT.' 
 
 ne 10. for "Fig. 1." read "Fig. 2." 
 
 ne 10. for " Zygnema altebnatum" read " Z. reversum." 
 
 ne 2. for " Plate LII. Fig. 3." read " Plate LII. Fig. 6." 
 
 ne 6. from bottom, for " Figs. 2, 7, 6." read " Figs. 1, 2." 
 
 ne 8. from bottom, for "Fig. 3." read "Fig. 1." 
 
 ne 10. for "Fig. 1." read "Fig. 3." 
 
 ne 9. for " Plate LXXV." read " Plate LXXVI." 
 
 ne 12. for "Fig. 15." read "Fig. 16:' 
 
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