arte i Pte ALBERT R. MANN LIBRARY AT CORNELL UNIVERSI¥Y Cornell University Library QL 391.04B3 oO 9 “HOT 3 1924 003 403 924 4 mann OLIGOCHAETA Rondon HENRY FROWDE OxrorD UNIVERSITY PRESS WAREHOUSE AMEN CoRNER, E.C. Mew York MACMILLAN & CO., 66 FIFTH AVENUE A MONOGRAPH OF THE ORDER OF OLIGOCHAETA BY FRANK EVERS BEDDARD M.A. (OxoNn.), F.R.S. PROSECTOR TO THE ZOOLOGICAL SOCIETY OF LONDON | AND LECTURER ON BIOLOGY AT GUY’S HOSPITAL OXFORD AT THE CLARENDON PRESS M DCCC XCV Orford PRINTED AT THE CLARENDON PRESS BY HORACE HART PRINTER TO THE UNIVERSITY PREFACE HERE are already two works dealing with the Order Oligochaeta. The first of these, in time of publication, is Professor Franz Vejdovsky’s ‘System und Morphologie der Oligochaeten,’ which appeared in 1884. Six years later Professor Léon Vaillant contributed to the volumes on the Annelids of the ‘Suites & Buffon’ a volume and a half dealing with the same group. It might appear, therefore, at first sight, that the ground has already been taken up, and that there is no occasion for the present work. It must be recollected, however, that it is nearly ten years since the publication of Professor Vejdovsky’s treatise, and that during this period our knowledge of the Oligochaeta, more particularly of the earthworms, has increased enormously. Professor Vejdovsky’s object, moreover, was more especially to give an account of the structure of the group from his own observations, and to spend less time in dealing with the results of other observers—not that the previous work upon the group was by any means neglected by him, but no great amount of detail was given as to the genera and species of Oligochaeta not occurring in his native country. M. Vaillant’s work is rather more comprehensive in scope, but there is no account of any researches made after the year 1886; so that the large amount of literature which has appeared since that date has not yet been _ incorporated into any general work. M. Vaillant’s contribution also is rather more devoted to the systematic side of the subject than to the description of structure. Under these circumstances it appeared to me that there was room for a treatise of rather wider scope than those of either Professor Vejdovsky or vi PREFACE of M. Vaillant, and one which should deal with the entire subject up to the date of publication. As will be seen from the bibliography which I have given in the Appendix, the literature of this subject is large and scattered ; so that to bring together under one cover all of importance that is as yet known about the group of the Oligochaeta will possibly be considered not to have been a useless performance. In attempting this labour I have received much kindly encouragement from Professor Ray Lankester, which I gratefully acknowledge. I have been so fortunate, through the kind influence of Dr. Burdon Sanderson, as to secure the assistance of the Clarendon Press, to the Delegates of which institution I wish to express my great indebted- ness. The cost of the necessary illustrations, which has been considerable, has been largely defrayed by the generosity of Mr. J. P. Gassiot, F.Z.S., who, at the suggestion of Mr. Sclater, has placed a sum of £100 at my disposal for this purpose. Without this very liberal act of assistance on Mr. Gassiot’s part this work could hardly have been undertaken. I may now say a few words about the scope of this monograph. The study of the group with which it deals is one which has occupied my leisure- time for the past fifteen years; I have had the opportunity of dissecting and examining most, if not all, of the more important types; so that while a good part of the volume is necessarily derived from compilation, a con- siderable proportion of it is the result of first-hand knowledge. Whilst I have amalgamated my recent papers into the present work, I have also incorporated with it a certain amount of new matter which I have not published elsewhere, and I have given, in the systematic part, descriptions of a few new species. I have not, however, made any lengthy investigations for the express purpose of this monograph, but I have in several cases verified the statements of others, and have corrected, in a few minor particulars, errors of observation on the part of myself, as well as.of other zoologists. Those who have not followed closely the progress of knowledge in this group of animals may be surprised at the large number of pages which it has taken me to set down the facts: I have erred, however, rather on the side of compression and omission than on that of undue prolixity. The omissions (with a few exceptions to be noted immediately) will not be found, I trust, to be of facts of much importance. They chiefly concern the progress of our PREFACE vii acquaintance with the group. It has not appeared to me to be necessary to go at great length into the history of erroneous views or of misstatements of fact—at any rate compression and omission here seemed to be more per- missible than in other departments of the subject. I have deliberately omitted to give any account of the early stages of the development of the Oligochaeta ; the development of organs will be found treated of to a certain extent. I determined to do this principally on account of Prof. Vejdovsky’s recently published ‘ Entwickelungsgeschichtliche Untersuchungen,’ an elaborate and finely-illustrated work, which goes into the matter with all details, and treats of the rest of the literature in a most thorough fashion. Moreover, I have personally no first-hand acquaintance with the early development of the Oligochaeta—another circumstance which leads me simply to refer to the work already quoted those who are desirous of ascertaining what is known about the embryology of the Oligochaeta. Another branch of the subject which I have thought it well to abridge is the section dealing with unrecognizable species. No name, I hope, has been omitted, and no reference ; but I have not, except in a few instances, gone at any length into the endless possibilities as to the identity of species imperfectly described and now irrecoverable. While this work was in preparation two excellent revisions of two families of the Oligochaeta have appeared: I refer to Dr. Rosa’s detailed account of the Lumbricidae, and to Dr. Michaelsen’s ‘Synopsis’ of the Enchytraeidae. The appearance of these two valuable papers caused me to hesitate a little before dealing with the respective families in this work. I have, however, thought it best to incorporate both of them, not, I hope, without critical examination. In the preparation of the systematic part of this monograph I received the greatest assistance from M. Vaillant’s work; I gladly acknowledge that it formed the basis of my preliminary (manuscript) account of many of the species of Oligochaeta, and that it has saved me a vast amount of labour in compilation ; I believe, however, that I have nowhere followed M. Vaillant’s descriptions and synonymies without careful verification and criticism. In the general sketch of the structure of the group I have only dealt with generalities; the details of particular, genera, or it may be of species, vill PREFACE will be found under their respective headings. My own experience is that in reading elaborate monographs the multiplicity of details tends to throw one off the main course of the argument. Details of minor importance are much better referred to their proper place instead of being included in one long dissertation on the structure of the group. I have therefore attempted to give in my introductory chapter such an account of the anatomy of the Oligochaeta as may be sufficient to satisfy any person not interested in the minute details, but desirous of having the main facts stated in as few words as possible. It may be thought that I have erred in the brevity of this chapter: I claim, however, to have put before the reader a more complete account of the structure of the group than can be found in any treatise yet published, and I have done my best to avoid details not of special significance except as generic or specific characters. In the systematic part I have not treated each family in a precisely similar fashion. In the Perichaetidae, for example, the internal structure is dealt with after the definition of the family; in the Geoscolicidae, anatomical details are reserved as generic characters. In the highly peculiar group Eudrilidae the method adopted is somewhat intermediate. In each case the plan followed is not, as might perhaps be suspected, the result of the dis- continuous preparation of this monograph, but has been deliberately selected as being, in my opinion, most appropriate to the family in question. For material used in the preparation of this work I am greatly indebted to Dr. Benham, Prof. Claus, Mr. W. T. Thiselton-Dyer, C.M.G., F.R.S., Mr. Chamberlain, Mr. Gustav Eisen, Mr. Everett, Mr. F. Finn, Dr. Gregory, Prof. Lovén, Dr. Michaelsen, Prof. M‘Intosh, F.R.S., Mr. Alvan Millson, Prof. T. J. Parker, F.R.S., Prof. Poulton, F.R.S., Dr. D. Sharp, F.R.S., Mr. W. W. Smith, Mr. Sowerby, Prof. Baldwin Spencer, Prof. Vejdovsky, the Rev. H. W. Woodward, the St. Petersburg Museum, and the Zoological Society of London. FRANK E. BEDDARD. Lonpon, February, 1895. TABLE OF CONTENTS DEFINITION OF OLIGOCHAETA PART I.— THE ANATOMY OF THE OLIGOCHAETA. Historican Note Tue Bopy-waLL AND ExTERNAL CHARACTERS Tue Nervous System CoErLom NEPHRIDIA ALIMENTARY CANAL VascuLaR SysTEM BLooD-GLANDs REsPrraTORY ORGANS REPRODUCTIVE SYSTEM . GrocrapHicaL DistRIBUTION PART II.— SYSTEMATIC. Tue CLASSIFICATION OF THE OLIGOCHAETA . PHYLOGENETIC ARRANGEMENT OF THE OLIGOCHAETA . : DESCRIPTIONS OF GENERA AND SPECIES Group APHANEURA Famity AEOLOSOMATIDAE Group MicropRILI Famity PHREORYCTIDAE . Famity MOoNILIGASTRIDAE PAGE 18 25 31 53 64 77 81 84 148 155 162 174 176 176 187 187 192 x TABLE OF CONTENTS SUPERFAMILY LUMBRICULIDES Famity LUMBRICULIDAE . Faminty TuBiFIcIpAE Famity NarpoMoRPHA Famity ENCHYTRAEIDAE . Group MEGADRILI SUPERFAMILY MEGASCOLICIDAE Faminty PERICHAETIDAE Famity CRrYPTODRILIDAE Famity ACANTHODRILIDAE Famity Evprinipar Faminy GEOSCOLICIDAE Famity LumMpricipa& BIBLIOGRAPHY INDEX OF GENERA AND SPECIES PAGE 206 207 226 275 308 357 357 359 443 516 573 622 687 725 753 EXPLANATION OF PLATES PLATE I. Fig. 1. Pertchaeta indica. Dissected. sp, spermathecae; g, gizzard; sp s, sperm-sac; dv, dorsal vessel; mph, nephridia ; sp gl, spermiducal gland ; caec, caeca. Fig. 2. Perichaeta everetti. Ventral view of anterior segments. sp, spermathecal pores; @ oviducal pore; @ male pores. Fig. 3. Polytoreutus magilensis. Ventral view of anterior segments. male pore; sp p, pore of spermathecal sac. Fig. 4. Octochaetus multiporus. Dissected slightly from the side. gl, peptonephridium ; g, gizzard; nph, nephridia; dv, dorsal vessel ; sp gl, spermiducal glands; m, nerve-cord; v v, ventral blood-vessel. Fig. 5. Perichaeta posthuma. Ventral view of worm; 2 oviducal pore; ¢ male pores; p, genital papillae. Fig. 6. Libyodrilus violaceus. sp p, spermathecal pore; ¢ male pore. Fig. 7. Hudrilus eugeniae. 9 female pore: g male pore. PLATES ITI ann III Generative organs of various types of Oligochaeta diagrammatically represented. The male organs are coloured pink, the female blue. To all the figures the following lettering applies: T, testes; F, sperm-duct funnels; sp s, sperm-sacs; 0, ovary; od, oviduct; e s, egg-sacs ; os, sper- mathecal sac; sp, spermathecae ; sp gl, spermiducal gland. PLATE IV. Fig. 1. Libyodrilus. Dissection. 0, orifice of spermathecal sac; sps, sperm-sacs; sp gl, spermiducal glands; vv, ventral blood-vessel; dv, dorsal blood-vessel ; .», nephridia. Fig. 2. Siphonogaster millsonz. Tr, penial (2) processes. The remaining figures bear a legend. In all of them the following is the significance of the letters: g, gizzard; ca, calciferous glands; sp, spermathecae; sp s, sperm-sacs; h, ‘heart’; sp gi, spermiducal glands ; vd, vas deferens; od, oviduct. The clitellar segments are numbered ; the dorsal vessel with its branches are coloured red. xii EXPLANATION OF PLATES PLATE V. Fig. 1. Stuhlmannia. Longitudinal section through anterior segments. br, brain; n, ventral nerve-cord; g, gizzard ; ca, calciferous glands; vv, ventral blood-vessel; dv, dorsal blood-vessel; s, masses of perivisceral corpuscles. Fig. 2. Octochaetus multiporus. Transverse section through oesophageal region of young worm. dv, dorsal vessel; vv, ventral vessel ; s, septum ; ca, calciferous gland ; , nerve-cord. Fig. 3. Hudriloides cotterilli. Transverse section. sps, spermathecal sac with appended glands (gl). dv, dorsal vessel ; ca, calciferous glands; 7, oesophagus. Fig. 4. Stuhlmannia. Section through penial process. gl, glandular epithelium of penis; m, septum dividing its cavity from general coelom; wd, vas deferens; mn, nerve-cord; dv, dorsal vessel; J, intestine ; el, clitellar epithelium; sps, sperm-sacs; p, muscular sac opening at end of penis. ERRATA . 183. To synonyms of Aeolosoma hemprichii add Acolonais hemprichit and Aeolonais decorum of GERVAIS. . 184. To synonyms of Aelosoma quaternarium add Aeolonais quaternarium of GERVAIS. . 214. To synonyms of Lumbriculus variegatus add Tubifew yentilinus, Duais (fide VAILLANT). . 229,114. For Telmatodrilus read J'elmatodrilini. . 251, 1. 24. For bogdunovii read bogdanovit. . 266, 1. 13. For Hemitubifes ater read Hemitubifex benedit. 275. To list of genera of Naidomorpha add Ripistes. . 285, 1.4. For O. josinae read NV. josinae. . 288, 1.12. For P. elinguis read N. elinguis. . 313, 1. 15. For vermiculus read vermicularis, - 332, footnote. For I. fusca read MW. semifusca. . 348,115. For £. hegemon read F. hegemon. . 394. A few species (10) have been accidentally omitted from the list. - 481. To synonyms of Fletcherodrilus unicus add Cryptodrilus pelewensis, MICHARLSEN. . 498, 1.13. For C. gravidis read C. grandis. . 530, 1. 18. For A. communis read D. communis. . 552, last line. For A. multiporus read O. multiporus. . 608, 1. 23. For P. elongatus read P. finni. . 661, 1,29. For U. papillata read U. papillifer. ssp twette Sos Norz.—Formal descriptions of Brachydrilus, Megascolex hallii, and of Perichaeta dubia, have unfortunately slipped out. But the principal facts in the anatomy of these species will be found scattered through the volume, and can be referred to from the Index. Plate L E.Wilson del Cambs University Beddard’s Monograph on Ohaocheta. J Lumbricus 4 Acanthodrilus. Lerichacta Monier gaster 7 Helrodrius Hyneriodrttus Ludrtlorvdes Beddard’s Monograph on Oligocheta. University Press 0; Plate Pontoadrilus Gordioarilus ee” Ocnerodrilus Trichokrutus s 8§ & o s Roe & & § XVIT University Press Oxf Phreoryctes Microchaeta Linchytraeed Beddards Monograph on Oligocheta. re) oO QCA x iS) S & S $ f ¢ \ Q / Ogene ily o fi Ay Universit Flate @ Monograph on Oligochast ard’s Lee tels KEKE ’ A MONOGRAPH OF THE OLIGOCHAETA. Class OLIGOCHAETA, Gruss. Def. SEGMENTED ‘ worms’ invariably hermaphrodite ; all the segments of the body— except the first and occasionally an additional and varying number at anterior end— setigerous, the setae usually /-shaped but showing variation in form, never borne upon parapodia. Excretory organs paired tubes metameric, or numerous in each segment and dysmetameric. Branchial organs, rarely present. Gonads limited in number (normally never more than two pairs of ovaries and testes); sexual products nearly always matured in special sacs developed from the septa. Special ducts carry off the genital products. Development direct. Terrestrial or fresh water, rarely marine, in habitat. PART I. THE ANATOMY OF THE OLIGOCHAETA. § 1. Historical Note. The Bibliography appended to the present work shows how very recent is our knowledge of the anatomy of the Oligochaeta. Of the exotic earthworms, which form so much the greater portion of the known species, there was absolutely no anatomical knowledge until the publication of VAILLANT’S memoir upon Perichaeta in 1868 (8); all that was known before this date from the contributions of F. 8. Lruckart, Rapp, TEMPLETON, and ScHMARDA relates to little beyond external characters. PERRIER’S researches, particularly his first memoir (6), gave the first indication of the very great structural variation exhibited by the terrestrial Oligochaeta. Since that date (1871) our knowledge has rapidly accumulated, particularly during the last ten years, by the investigations of Horst, MicaaELsen, Rosa and others upon the continent, SPENCER and FLETCHER in Australia, Ersen in America, and BenHam and myself in England. Before 1868 we were only acquainted with the structure of European Oligochaeta. The common carthworm (represented no doubt by several species) furnished material for a number of investigators ; B 2 OLIGOCHAETA Home, Leo, Morren published their researches, but our present accurate knowledge of that animal may be said to date from the memoir of D’UpEKEM (4), who first discovered the ovaries. Subsequently to that LANKESTER (9), CLAPAREDE (1), Horst (1), v. Mossisovics (1, 2), CERFONTAINE, and others have dealt with the structure of Lumbricus. The aquatic Oligochaeta of Europe were first investigated by O. F. MUtueR; but p’'UDEKEM’s memoir upon Tubifex, and those of CLAPAREDE upon that and other forms, are the memoirs from which our modern knowledge dates. Since the publication of CLAPAREDE’s two memoirs, the aquatic Oligochaeta have been principally studied by LANKESTER, BENHAM, and myself in this country; on the continent by Lnryp1¢, DIEFFENBACH, and others; in Arnerica by EISEN. 1. Tae Bopy-WarLt AND EXTERNAL CHARACTERS. § 1. External form and segmentation. The Oligochaeta are segmented worms of very variable size ; at the one extreme we have the minute species of Aeolosoma and certain Naids, 1 mm. or so in length; at the other the gigantic Microchaeta rappi and Megascolides australis, which measure from four to six feet. In all the Oligochaeta, with the exception of Aeolosoma, where it is at any rate less marked, the external segmentation corresponding to the internal metamerism is very obvious. The grooves which separate the segments from each other are clearly defined. It often happens however, particularly among the larger earthworms, that there is a ‘secondary’ annulation of the segments. The term ‘secondary’ is used, because this division of the segment by transverse furrows into two or more parts appears to have no relation to other organs, whether internal or external; at the same time this annulation of the segments and the number of annuli appears to be fairly constant for the species. The number of segments in the body of the Oligochaeta is very small (6-20) in Aeolosoma, and some others among the lower forms. As many as 500 or 600 segments have been counted in some of the larger earthworms. There are at present no exact data as to the constancy of the number of segments among earthworms.’ In all probability the number is not absolutely fixed, but there appears to be a mean for each species round which there is a certain amount of variation. There is but little specialization among the segments of a worm’s body ; it is an invariable rule that the first segment of the body, and it occasionally happens that a few of the following segments also, are devoid of setae ; this ‘ cephalisation’ is dealt with more at length on a subsequent page. As arule the anterior segments of the body in earthworms are wider and marked by more numerous secondary annulations than those which lie behind the clitellum ; the clitellum itself is formed by a specialized set of segments. § 2. Prostomiwm. In the majority of Oligochaeta a process of the first segment of the body overhangs the mouth on the dorsal side. In afew forms it is of considerable length, THE ANATOMY. PROSTOMIUM 3 and no doubt plays an important part as a tactile organ; in the majority of Oligochaeta it is not large, and in a few it seems to be totally absent. This ‘prostomium,’ ‘ prae- stomium,’ ‘ buccal lobe,’ or ‘ upper lip,’ as it has been variously termed, is often separated by a furrow from the first segment of the body —the buccal segment, of which it is a process. Sometimes the separation is not marked at all, or hardly marked by two teral furrows which converge towards the middle line but do not meet. The genus Lumbricus (e. g.) and a few species of Acanthodrilus exhibit a very curious condition of the prostomium ; it is separated from the buccal segment by a cross furrow, but from the angles of this arise two longitudinal furrows which end at the posterior extremity of the buccal segment and as it were continue on the prostomium over this segment. The prostomium has in this case the appearance of being a process of the second segment of the body. Frienp has recorded in Allolobophora chlorotica (9) a remarkable extension backwards of the prostomium which reaches as far as the end of the fourth segment, This, it should be stated, is not a characteristic of the species in question, but an occasional variation. The genus Phreoryctes has a prostomium which is rather elongated and is divided into two halves by a cross furrow at about the middle of its length. In this particular it recalls the Capitellidae. An elongated prostomium—longer than in Phreoryctes—chearacterizes Nuis lacustris. The names Nats proboscidea, ‘ die geziingelte Naide,’ given to it by various writers, are expressive of that peculiarity. The long prostomium of Rhinodrilus gulielmi and of Trichochaeta hesperidum has a peculiar structure which has not been described elsewhere. In the former species, I erroneously stated that the prostomium was altogether absent; it is however present, but at times retracted, so that it is not at all conspicuous ; at such times it protrudes from the buccal orifice as a slight conical projection. A prostomium of apparently precisely the same character exists in Trichochaeta; in that genus I have investigated its structure and relations by means of sections. It protrudes in a fashion similar to that of Rhinodrilus from the mouth, and in sections is seen to arise from a slight invagination of the dorsal wall of the buccal cavity just in front of the brain and at a point posterior to the orifices of the first pair of nephridia. According to VAILLANT the prostomium of Rhinodrilus paradoxus is similarly an ‘extroversion’ of the buccal cavity. It is quite possible that in Trichochaeta, when the prostomium is completely everted (necessarily along with the most anterior section of the buccal cavity), it may have the appearance of being merely a process of the buccal segment, and may indeed prove to be morphologically such, and therefore comparable to the prostomium of other worms. In the meantime I am inclined to think that it B2 4 OLIGOCHAETA is an organ of a rather different nature, possibly comparable to the introvert of the Gephyreans. In a few earthworms the prostomium seems to be completely absent. PERRIER and I myself did not find any trace of the prostomium in Pontoscolex, but Horst has subsequently affirmed its existence. There appears however to be no prostomium in Deodrilus. Is the absence of the prostomium to be regarded as an archaic character or as due to degeneration? The two alternative views have been put forward. They depend of course upon the morphological nature of the prostomium, concerning which again there are two current views. Wi1son in his lately published account of the development of the earthworm holds that the prostomium is a segment; the only difference which it shows from other segments is that its cavity is unpaired. Wutson explains this by looking upon it as the terminal segment of a body which represents an elongated ring,—the view in fact that the Annelid’s body can be derived from a Coelenterate pulled out lengthwise. VrJDOVSEY (9), on the other hand, found that the prostomium was a comparatively late development—undoubtedly an outgrowth of the first segment. The mouth is originally completely terminal. § 3. Eaternal Apertures. In many earthworms various pores upon certain of the segments are visible ; these are (1) the dorsal pores opening into the body cavity, (2) the external pores of the nephridia, (3) and lastly the apertures of the reproductive ducts. The varying position of these pores will be found mentioned under the various organs of which they are the outlets, either in the general part of this work or in the systematic _ section. A few general observations however may find a place here. The older naturalists used the varying position of these different pores for the purpose of specific and generic definition—usually with questionably useful results; nevertheless it is possible for a person conversant with internal structure to make a pretty accurate guess by the external characters alone as to the genus, or even in a few cases the species, which he is examining. Most conspicuous of all the external orifices are as a rule the male pores; it is only in the Geoscolicidae and in some species of Lwm- bricus that they are not obvious, for the reason that the sperm ducts do not terminate in a spermiducal gland; in Allolobophora they are conspicuous, although they do not terminate in such a gland, for the integument is swollen and glandular at their point of opening: in this case the position is always the fifteenth segment; if the pores are obvious and upon the eighteenth segment the genus will be certain to be one of the Crypto- drilidae or Perichaetidae (which can be further differentiated of course by the setae). If the male pores are double and upon segments seventeen and nineteen the worm will be an Acanthodrilid. In all Eudrilidae the male pores are exceedingly conspicuous; THE ANATOMY. SETAE 5 they are in this family nearly always unpaired and median. The pores of the spermathecae are not always so visible; they are however for the most part in the Eudrilidae, where the pore is single and median. The accompanying plate (Pl. I) shows how great the external differences may be between earthworms, though in general shape they are so much alike. § 4. Setae. In all Oligochaeta, with the single exception of Anachaeta (woodcut, fig. 1), there ave chitinous rods formed by epidermic cells and arranged in a certain definite plan, which are most usually Fig, 1. termed ‘setae’; these setae are partly buried in the thickness of the body-wall, and are prolonged into the body-cavity ; the free extremity projects for a varying distance beyond the epidermis; the setae are the organs of locomotion of the animals ; they are furnished with special muscles which enable them to be retracted or pro- tracted and pulled forwards or backwards ; progression is effected by their movements. It used to be believed that the setae were structures of mesoblastic origin; but it is now, through the researches of VEJDOVSKY and others, so firmly established ANACHAETA BOHEMICA. that they are epidermic that it seems to be (Attes Michaelson) ‘aul s He hi : 1. Gland cells=dorsal setae of other forms. 2. Clitellar of no particu ar use to go into the istory epidermis. 3. Lateral line. 4. Openings of sperm-ducts. of the older and erroneous view. The setae & es oe ee are implanted in sacs which are diverticula c@nel. 10. Longitudinal muscles. of the epidermis; at the margin of these sacs the chitinous cuticle is invaginated and forms a lining for the seta sac down to a certain depth ; beyond this the seta is imbedded in a mass of cells, each one of which can produce a new seta to replace the original one. The invaginated part of the epidermis consists of a row of low cells lined by the cuticle already mentioned, and terminating in the mass of cells without cell boundaries in which the seta is firmly imbedded ; often, as Vespovsky has figured for Rhynchelmis, the sac is reinforced by a second sac lying near to it, also multicellular and containing a seta in course of development. The setae first appear as small cones of chitinous substance ; the apex of the seta, its free extremity, is first developed; it then gradually grows in length. A single sac (which it must be remembered is multicellular) often contains, as in the Tubificidae, a large number of setae. The invaginated epidermis does 6 OLIGOCHAETA not always appear to exist; thus in T'wbifew (NassE) and Linvnodrilus (VEJDOVSKY) no such hollow sac is figured; the setae and the solid mass of cells in which they are imbedded reaching right up to the epidermis : in these cases however there seems to be an invagination of the chitinous layer; hence it is possible that a tube of epidermis is also invaginated. CrRFronTAINE (1) has figured two sections out of a series through a seta sac parallel to the surface of the body; near to the external surface the seta is scen to be surrounded by a tube whose walls are composed of about fifteen cells; this region is the tubular invagination of the epidermis ; further down the number is reduced to four and then to two which are flattened and concave, closely embracing the setae, the special lining of chitin present in the more superficial part of the tube being here absent. In Anachaeta, as has been already mentioned, there are no setae at all; but the recent existence of these structures appears to be shown by the presence of large sacs depending from the epidermis on the dorsal side of the body, not the ventral, or (Anachaeta eiseni) on both: these sacs are apparently the equivalents of the seta sacs, and consist of a large cell of a glandular appearance with one or two nuclei near to its free extremity. The form of the setae in the Oligochaeta is varied; but they may be grouped into two divisions, (1) long slender setae gradually diminishing in diameter towards the pointed extremity, and (2) shorter setae of a curved form, something like an elongated S with a thickening at about the middle; the shape of these setae has been aptly compared to that of the mathematical sign /. The capilliform setae only occur in the aquatic Oligochaeta, and not in all of them. The sigmoid setae vary very much in the details of their shape. The simplest form is that which characterizes the vast majority of earthworms, the Phreoryctidae and many Lumbriculidae. These setae end in a pointed extremity. In Onychochaeta the extremity (fig. 2a.1) may be markedly hooked, In Pontoscolex among earthworms, in certain Lumbriculidae, in all Tubiticidae and Naidomorpha the sigmoid seta is cleft at the free extremity (woodcut, fig. 2b. 4). A further complication is seen in Twbifea and other Tubificidae, where there are a few subsidiary prongs arising between the two main prongs into which the extremity of the seta is cleft (woodcut, fig. 2b. 6); this later form of seta may be termed ‘ pectinate, the simply cleft seta ‘uncinate. A remark- able variation characterizes Heterochaeta, and to a less extent Psammoryctes and Spirosperma (woodcut, fig. 2b. 3), where the widely divergent prongs are united by a ribbed membrane. This form of seta has been termed ‘palmate.’ Another form of the uncinate seta characterizes certain Naidomorpha. The seta (woodcut, fig. 2b. 7) is straight instead of being curved, and has a cleft extremity. This form is termed THE ANATOMY. SETAE 7 ‘hastate. The Enchytraeidae show another form of sigmoid seta which is nearly perfectly straight but has not a cleft extremity. Another modification of the sigmoid seta is especially characteristic of the family Geoscolicidae among earthworms, though not unknown elsewhere. The end of the seta, which protrudes from the body, is ornamented (woodcut, fig. 2 a. 2, 3) with transverse ridges (Pontoscolex) or with minute spinelets (T’richochaeta). The capilliform setae, (fig. 2b. 2) which are exceptionally (Lophochaeta) covered with fine processes (woodcut, fig. 2b, 5), compar- Fig, 20. able perhaps to the ornamentation of the sigmoid setae in Trichochaeta, to some extent graduate into the sigmoid setae, The intermediate condition is seen in Phreodrilus, where the capilliform setae are shorter, stouter, and more curved than in other Tubificids. As Phreodrilus is in other respects a link between the Tubifi- cidae and Lumbriculidae, the fact gets an additional interest. It sometimes happens that a worm has setae of one kind only from head to tail. This state of affairs however is the less usual. Among the aquatic forms certain species of Aeolosoma, and of the Tubifi- cidae (Limnodrilus), Enchytraeidae, and PS Ee ‘ : + Rn re ees Lumbriculidae, are the only instances. SS Among earthworms the Moniligastridae, ti By . < ~ 7 many Megascolicidae, and some Lumbri- naa —— 4 Se cidae and Eudrilidae are ena ee SS The commencement of a diversity : in the form of the setae is seen in Phreoryctes, where some of the setae are i Fig. 2a. 1. Onychochaeta windlei : posterior seta. z. Ornamented longer than the others — the dorsal longer seta of Geoscolecid. 3. Trichochaeta hesperidum. 3b. End of set same more highly magnified. _ than the ventral, or vice versa, OF the pos- Fig. 2b. 1. Penial seta of Acanthodrilus georgianus. 2. Spiro- ‘erior longer than the anterior ; in many ema JSerox, 3, Spirosperma ferow. 4. Ilyodrilus coccineus. 5. te 5 ” y Lophochaeta ignota. 6. Tubifex rivulorum. 7. Nats elinguis. Perichaetidae the ventralmost setae are 8. Nais elinguis. 9. Bohemilla comata. longer than the others ; in some those upon a few of the anterior segments are longer than the rest. SETAE OF OLIGOCHAETA. (After Vejdovsky, Stole, Michaelsen.) 8 OLIGOCHAETA Another stage is seen in many Geoscolicidae and Lumbricidae, where the setae upon the clitellum are longer than the others and of a slightly different shape ; it occurs for example sometimes in the Geoscolicidae that the clitellar setae are ornamented, while those formed elsewhere are not. In the Eudrilidae the setae are apparently similar throughout the body except in the neighbourhood of the male pore. These penial setae (see under description of reproductive system) occur in many Oligochaeta. It is however among the aquatic genera that the greatest specialization of the setae occurs. Among earthworms a single segment has never setae differing in form though they may differ in size, excepting only in the case of the segments which bear the specially modified penial setae, which may be a little different among themselves and are as a rule very different from the ordinary locomotive setae on the same segment. But the rule among aquatic Oligochaeta is that the dorsal bundles of setae should contain setae different in form from those of the ventral bundle. In most Tubificidae the dorsal bundles are made up of capilliform setae, with which may or may not be mixed uncinate setae ; the ventral bundles are entirely composed of the latter. The details in the distribution of the setae, which are most useful for classificatory purposes, will be found in the systematic part of this work. The arrangement of the setae among the Oligochaeta is varied. The most prevalent plan is the existence of four groups of setae, which of course recall the parapodia of the Polychaeta. The principal ways in which the setae are disposed are indicated in the following table :— 1. Setae numerous in each segment and forming a complete ring—Ex. Perichaeta, Pleionogaster, and other Perichaetidae. , 2, Setae numerous but arranged in two lateral masses leaving dorsal and ventral gaps.—Ex. Megascolex. . 3. Setae twelve in nurnber in each segment.—Ex. Deinodrilus. 4. Setae eight in each segment placed at equidistant intervals or grouped into four pairs, or intermediate, four setae being paired and four distant.—Ex. Acanthodrilus, Lumbricus. 5. Setae eight in number in anterior segments, and thence increasing to thirty or forty.— Ex. certain Perichaetidae. 6. Setae in four bundles with more than two setae in each bundle —Ex. Tubificidae. 7. One pair of setae only on each side of segments.—Ex. Anachaeta. 8. Setae, eight in number in each segment, but irregularly arranged.—Ex. Diachaeta. It will be seen from the above table that there is an almost unbroken series of stages in the arrangement of the setae ; we can pass from one extreme to the other without any difficulty ; thus assuming for the moment that the original condition is exemplified by THE ANATOMY. SETAE 9 Perichaeta, a gradual reduction in the number of the setae anteriorly leads to certain species of Megascolez; a reduction upon all the segments of the body simultaneously leads through Deinodrilus to Acanthodrilus, &e.; on the other hand, a crowding together of the setae into four bundles coupled with a reduction in numbers, brings about the arrangement characteristic of the Tubificidae. It is however by no means certain that the stages have been developed in the order suggested above. There appear to be three possible lines of development; either the * perichaetous’ condition is the most primitive, or the two pairs of setae in each segment, or the bundles with several setae (more than two) in each bundle. We shall consider these various possibilities seriatim. If we regard the Oligochaeta as to be derived from the Polychaeta it is clear that the last of the three alternatives is the one which would then appear to be the most probable; the considerable specialisation in the individual setae of a bundle is a further point of resemblance to the conditions characteristic of many Polychaeta. But there is not after all much detailed resemblance between the setae of the Tubificidae and those of the Polychaeta; the fact that in both groups the setae of the dorsal bundles are very often different in form from those of the ventral bundles is perhaps more striking as an analogy than valuable for the purposes of a strict comparison; if the differences were of the same kind it would be different. Still it might be urged that in the Tubificidae there is a resemblance to the Polychaeta toned down by simplification. Furthermore, we have the extinct Pronaidites; this worm has been referred to the Oligochaeta (Kusta), but it is not by any means convincingly an Oligochaet. As the creature is of Carboniferous age, this argument would be strongly supported if it were proved beyond doubt to be referable to the Oligochaeta. Unfortunately, this is the only piece of palaeontological evidence bearing upon the matter under discussion, and at best it is not conclusive in any direction. Besides, looking at the matter in another light, there are now undoubted Polychaeta known which inhabit fresh water, for example Manayuwnkia. The only families of Oligochaeta which show this resemblance (such as it is) to the Polychaeta in the arrangement of their setae are the Tubificidae, Naididae, and Aeolosomatidae; and they are all, it will be observed, aquatic in habit. Now it seems quite reasonable to suppose that long and delicate setae would be out of place in a worm having to force its way through dense soil; we need not therefore be surprised at not meeting with such setae among the terricolous forms; but there does not appear to be any valid a priort reason against finding bundles of short and strong setae in the land Oligochaeta; and yet there are only the Enchytraeids among the terrestrial Annelids with such an arrangement of setae, and they are largely aquatic. One is accordingly inclined to c 10 OLIGOCHAETA suppose that after all the bundles of setae have some relation to the aquatic life ; it is quite possible that a number of them radiating out in a fanlike way serve as an efficient swimming organ, and hence their development in Oligochaeta which occasionally at least ‘swim.’ If there were any other reasons for associating together the families of Oligochaeta mentioned with the Polychaeta, this question of the simi- larity in the disposition of the setae would have to be reconsidered; but it cannot be said that the Tubificidae and the Naids are nearer allies of the Polychaeta than any other families of Oligochaeta; hence I am inclined for the present to put down the likeness in the bundles of setae in the marine and in the fresh water Annelids to a similar need. E:sic has dealt with this subject in his Monograph of the Capitellidae (p. 574, etc.). In that group there are forms in which the distichous arrangement, obvious elsewhere, is nearly lost; a state of affairs very like that of Perichaeta thus results, or more like Megascolez, since there are dorsal and ventral gaps. There can be no doubt, in E1si@’s opinion, that the later arrangement is secondary, it being restricted to the beginning of the abdomen, and being preceded as well as succeeded by the ordinary paired bundles. One argument in favour of deriving the fewer setae per segment of most earth- worms from the perichaetous condition does not appear to me to have been considered. That argument is based upon the fact that in most Perichaetidae the number of setae is less in the anterior than in the posterior segments of the body. In a number of species, which I formerly proposed to place in a separate genus Anisochaeta, there are eight setae in a varying number of the anterior segments, while posteriorly the number becomes much greater; this is an extreme case of the point at issue; but in all Perichaetidae there seems to be a smaller number of setae on the pre-clitellian segments than upon those which follow, or there is a progressive increase for a few segments at any rate. In Megascolex this is, so far as we know, invariably the case ; but in Perichaeta the number, after increasing up to a certain segment (for example the seventh in P. taprobanae), diminishes. Now in such a form as Onychochaeta the absence of setae upon the first few segments of the body (seen also in other Geoscolecids) must surely be regarded as an instance of what has been called ‘cephalisation’; it is at any rate a modification paralleled by other organs of the body. It would seem therefore likely that the smaller number of setae in the anterior segments of the body in the Perichaetidae is due to a reduction from a primitively greater number; as we know that this number is sometimes reduced to eight we have the origin of the eight setae per segment of the majority of the terrestrial Oligochaeta suggested. Such general arguments as can be deduced from THE ANATOMY. CEPHALISATION 11 the primitive position of the Perichaetidae among earthworms can also be used; this matter however is discussed later. Spencer has referred to the existence in Megascolex of what would seem to be a regenerating tail; and it is noteworthy that here the setae are more numerous than anteriorly; it suggests a recurrence to an earlier condition. Why the number should have been reduced to eight exactly is a more difficult matter; it is a problem comparable to that involved in the attempted explanation of why earthworms should usually have two pairs of testes and certain species four pairs of spermathecae. There is no obvious advantage to be discerned in either fact. Typically the setae are repeated from segment to segment, with or without modification in form in different parts of the body or in different regions of the same segment. It sometimes happens, however, that the setae are partially or entirely missing upon certain segments of the body. These segments are either the first few segments of the body or certain of the genital segments. I have already mentioned the entire absence of dorsal setae in Chaetoguster and of all the setae in Anachaeta. In the segments which bear the male pores the ventral setae are very commonly absent; this is the case for example with Dero and with a good many earthworms (e.g. Ocnerodrilus, Megascolides orthostichon); in Psanvmoryctes barbata the dorsal setae also of the segment (eleventh) which bears the male pores are absent. A more remarkable instance of a specialisation of this kind occurs in a large number of species of Perichaeta. In those species, for example in the common P. indica, the three segments of the clitellum are quite without setae. Various inter- mediate conditions between the total absence of setae and their presence to the full number are seen in other species. There seems also to be a tendency in other earthworms for the clitellar setae to disappear, though sometimes, as has been already mentioned, the converse occurs, and they become replaced by a series of a different form. § 3. Cephalisation. LaNnkEsTeR has applied this expression to the specialisation of the anterior segments of the body so frequently seen among the Oligochaeta. As already mentioned, all Oligochaeta show cephalisation as regards the first segment of the body, which never possesses setae. There are a few earthworms in which more than the first segments of the body are without setae; these worms chiefly belong to the family Geoscolicidae, and the number of segments which are thus without setae differ in different species. There are as many as twenty in Kynotus. The Geoscolicidae are not the only family which show this character ; in the genus Deodrilus, belonging to the Cryptodrilidae, the first segments are similarly devoid of setae. Among the Naidomorpha, the cephalisation affects the dorsal bundles of setae only; ‘in Chaeto- o2 12 OLIGOCHAETA gaster, however, there are several segments following the first setigerous segment, which have no setae; in the other Naids a variable number of segments, varying with the genus, are without dorsal setae; for the details the reader is referred to the special description of the family. The only other examples among the lower Oligo- chaeta are afforded by Enchytraeus monochaetus and Hesperodrilus albus. The formation of a head or cephalisation is not however confined to the absence, or reduction in number, of the setae. Other organs show analogous modifications. It is common, for instance, to find the intersegmental septa not clearly definable in the first two or three segments of the body; their place is taken or their existence is concealed by masses of muscular fibres which pass from the buccal cavity and pharynx to the parietes. In all Oligochaeta a certain number of anterior segments of the body are without nephridia, or the nephridia if present are modified. There are various other organs which show peculiarities at the anterior end of the body and contribute to the formation of a ‘head.’ § 6. Eypidermis. The epidermis of all Oligochaeta consists of cells which are separated from the subjacent muscles by ‘a condensation of the connective tissue of the latter layer, which presents in parts the appearance of a veritable lamella’ (CER- FONTAINE). CLAPAREDE, adopting WEISMANN’s term—hypodermis, described this layer in Lumbricus as consisting of a nucleated meshwork in which no cell-outlines could be distinguished, enclosing spaces filled with a colourless substance; these bodies were regarded as of a glandular nature, but no nucleus was discovered. Leypia’s earlier view (6), based upon a study of Phreoryctes as well as Lumbricus, of the cellular nature of the entire epidermis was discarded, except for the prostomium, where CLAPAREDE detected in osmic acid preparations its cellular character. This erroneous view appears to have been first rectified for Lumbricus by PERRIER (9) in a preliminary dissertation upon the structure of that worm, which precedes his account of the anatomy of Urochaeta. A few years later the cellular nature of the epidermis was stated by LayxestTer (12); he speaks of it as consisting of ‘varied forms of goblet cells and, excessively delicate, elongate, interstitial, or “packing” cells, instead of the altogether improbable syncytium of CLAPAREDE.’ These results are mentioned as being confirmatory of those of Horst and v. Mosstsovics, which had been published previously. Since that date all observers have agreed in regarding the epidermis as distinctly cellular and built up of the two kinds of cells referred to in the quotation from LANKESTER’s memoir. CERFONTAINES memoir, published in 1890 (1), contains the most detailed account that has yet appeared of the epidermis of Lwmbvicus. The cells are disposed in two rows, the cells of the innermost row being small. THE ANATOMY. EPIDERMIS 13 These latter are pointed at one extremity, the fine process running up between the other cells; these cells are termed by CreRFoNTAINE ‘cellules de remplacement, inasmuch as they appear to replace the other cells of the outer layer. The outer layer itself is composed of two sorts of cells, of large oval glandular cells and of the interstitial cells; the former are large oval cells filled with numerous granules; the basal portion of the cell. in which lies the nucleus, is more protoplasmic and is narrower than the swollen upper part; the cell ends above in a fine prolongation which opens through a pore on the cuticle. The interstitial cells are of much less diameter; they often appear in cross sections to have excavated surfaces ; and in fact they are moulded to the form of the glandular cells which lie amongst them. The distal extremity of these cells is frequently prolonged or rather frayed out into a number of fine processes which seem to be in connexion with nerves. The cells of the epidermis are imbedded in a homogeneous connecting substance, which is more evident where the cells diverge from each other at the point of contact with the cuticle. This connecting sub- stance leaves a polygonal meshwork upon the cuticle, which is visible when the latter is viewed from the under surface. The cuticle seems undoubtedly to be a formation of the packing cells of the epidermis; the pores upon its surface are the outlets of the gland-cells, and their existence appears to be simply due to the fact that the gland-cells do not secrete a cuticle like the other cells, their secretory activity being taken up in the formation of the granules with which they are laden; hence at the points where they abut upon the cuticle there are gaps—the pores in question. The cuticle is sometimes distinctly to be seen as a double layer; viewed superficially it is seen to be traversed by two sets of striae, crossing each other at a right angle ; these striae correspond to two sets of fibrils, which are not upon the same plane, and therefore give rise to the double layer already referred to. The striation is thus not merely an optical effect, but is due to the composition of the cuticle out of numerous fine strands of cuticular substance. Clitellar epidermis. The epidermis on the clitellum is modified in structure. In Iumbricus it has been described, especially by CraparEpE, Horst, Mosuisovics, CERFONTAINE, and quite recently by CoLz. The clitellum in the most fully developed portion, that is to say on the back of the animal, is made up of several layers of glandular cells. There are first of all elongated gland-cells of cylindrical form, which are filled with granules, save at the inner extremity which is protoplasmic, and contains the nucleus. These gland-cells do not extend for a great distance into the thickness of the clitellar epidermis ; below them are the second sort of cells which are massed together into columns; there are several layers of these cells, and the axes of the columns which they form are 14 OLIGOCHAETA occupied by their processes which extend up to the cuticle. The columns are separated from each other by septa of a kind of connective tissue, which is fibrillated, and ends below upon the circular muscular layer, but not in actual connection with its fibres. In the fully developed part of the clitellum there are no non-glandular epidermic cells; these exist, however, on the ventral surface of the body in the clitellar region. The epidermis, both clitellar and non-clitellar, of other earthworms seems to be like that of Lumbricus, which has just been described. In M2crochaeta, however, Benuam has stated that the gland-cells seem to be more numerous than in Lumbricus ; such also appeared to me to be the case with Pontoscolex ; the clitellum of Microchaeta has been described and figured by BenHam (2). In addition to the layers which have been described above for Lwmbricus, and which occur in Microchaeta, there is an outer layer exactly like the epidermis of the general body-surface; it has not only the interstitial cells which, as already mentioned, occur in Lumbricus in the less deeply modified clitellar regions, but also the oval gland-cells; Bennam does not state from what region of the clitellum his sections were taken. In the lower Oligochaeta there can generally be distinguished the two kinds of cells in the epidermis. In H'nchytraeus mébit among the Enchytraeidae the gland-cells are not, comparatively speaking, very numerous ; in Phreodrilus and Pelodrilus I (21) recognised the same two varieties of cells ; in Aeolosoma the gland-cells contain a coloured substance which is frequently very characteristic of the species; for example in Ae. quaternariwm the oily substance is red; in Ae. headley a bright green ; in Anachaeta bohenvica there are three varieties of the glandular cells, colourless cells which are either elliptical or more spherical in form, and larger cells with green contents, the substance being chlorophyll. The clitellum in all the lower Oligochaeta shows no great differences from the ordinary epidermis; the same two kinds of cells are present, but the gland-cells are commonly more abundant and larger. The clitellum of the lower Oligochaeta has been described especially by VesDovsky (24), but also by others—for instance MICHAELSEN (Anachaeta), Stouc (Aeolosoma), myself (Moniligaster), etc. The morphological difference in the clitellum of the Jower and the higher Oligochaeta is duly insisted upon later. In the former, as will have been observed, it is less modified and is only a single layer of cells thick. Sense organs of epidermis. The cells of the epidermis are in parts modified to form sense organs. It is possible that the fine processes which arise from the epidermic cells in Aeolosoma and in many Naids have a sensitive function ; but there is apparently no particular modification of the epidermis to be traced in connexion with them, though in Bohemilla Vespovsky figures ganglionic enlargements upon twigs which THE ANATOMY. SENSE ORGANS 15 arise from the cerebral ganglia and end in these processes; however, it is common among the Oligochaeta for the epidermis of the prostomium to be modified to the extent that it has no gland-cells and is formed of deeper cells than is the epidermis elsewhere ; in the genus Aeolosoma and in the perhaps closely allied Ctenodrilus the under side of the prostomium is ciliated and there are a pair of lateral ciliated pits, possibly of a sensory nature. In the Naidomorpha we meet with the definite sense organs possibly of a tactile nature; in the genus Slavina there are a series of these ‘Sinneshiigel,’ as Vespovsky has called them, on each segment, the actual arrangement differing with the species ; these elevations consist of specially elongated cells which terminate in fine processes projecting beyond the cuticle. In Lumbriculus the same author has figured ‘ Becherformige Organe,’ which appear to be very similar; they are hemispherical elevations of the skin due to the elongation of groups of epidermic cells, which terminate in the same way in fine processes. In Rhynchelmis there are developed, at the breeding season, continuous zones of sense-cells arranged in groups; the cells have the same elongated form that the sense-cells generally show, and appear also to possess the fine processes already mentioned ; VespovsKy believed that he could trace nerves into connexion with these cells. VEJDOVSKY and CERFONTAINE have described and figured groups of what appear to be sense-cells in Lumbricus, these consist of long cells which are so arranged as to project slightly from the general body-surface ; they are furnished at the extremity with fine processes and occur chiefly on the anterior part of the body, often in particular proximity to the setae. Among the exotic earthworms but little is known of sense- organs; MICHAELSEN has figured and described in Acanthodrilus georgianus a pair of papillae on the tenth segment which would seem to be sense-organs rather than glandular modifications of the epidermis; they consist of the same kind of elongated cell that is usually associated with sense-organs; and fine strands, apparently of a nervous nature, could be traced into them; it is very possible that similar papillae, many of which, indeed most, have not been subjected to microscopic examination in other Acanthodrilides and other earthworms, are sensory in function. Eyes are present in a few Naids. They appear to consist of a lens-like body embedded in a cup of.pigment; a strong nerve from the brain supplies each eye. In the genus Pontoscolex and also in the nearly allied Onychochaeta there are certain peculiar epidermal structures which may be of a sensory nature; these were first described by Perrier and have since been described and illustrated by Horst and by myself in the same genus. They consist of a large spherical deeply staining cell imbedded in a large sac which lies at the base of the epidermis; the cell has a conspicuous nucleus, as is shown in the figures of both Perrizr and Horst. The 16 OLIGOCHAETA sac in which the cell in question lies seems to be connected with the surface by a canal; such a canal is figured by Perrier, but Horst does not indicate it distinctly. Vespovsky compared these cells with the large cells in Anachaetu, which represent the missing setae ; I supported that contention because it appeared to fit in with my view that the ‘ Perichaetous’ condition is the more primitive, and that these cells were the remains of-a Peri- chaetous condition in Pontoscolex ; I am not now convinced OF ae ee Ne EPIDERMAL SENSE cELL Of the justice of this view—which is not shared by Horst ; OF PONTOSCOLEX. it seems probable, as he suggests, that the cells are of (After Horst.) ~ The cell is in the middle ofthe S@S0ry nature; as to the special sense of which they are figure. the organs that is a matter impossible at present to decide ; it is just conceivable that they may be rudimentary eyes; the central cell appears to be highly refractive and a ray of light would pass through it to the tissue below; but the entire absence of any pigment layer in connexion with the organs seems to negative the likelihood of that view. In the meantime, the accompanying woodcut expresses the general form of these organs which may be regarded as sense-organs of some kind. I did, but do not, compare them to the ‘Pacinian bodies’ of Ludrilus, ete. A peculiar form of sense-organ is to be met with in many Eudrilids. These organs were first described by myself in Hudrilus (62) and compared, erroneously as I now think, with the epidermal bodies of Pontoscolex that have just been described. Since then they have been studied by Horst in Eudrilus and by myself in several other genera, such as Hyperiodrilus Fig. 4. and Heliodrilus. They are somewhat oval bodies, and lie just below the epidermis, though above the circular muscles; the cells of the epidermis — which cover them are shorter than the others and not glandular. These bodies consist (see fig. 4) of a deeply staining granular nucleated cylindri- HYPERIODRILUS. EPIDERMAL SENSE BODY. cal core, round which are apparently 1. Nerve supplying it. wrapped a series of membranes, also nucleated, though with smaller nuclei than the core; the whole structure reminds one most forcibly of a Pacinian corpuscle. In more than one case I fancied that I could detect a nerve fibre passing from the core, and I have represented one in the accompanying woodcut. There is nothing exactly comparable to these organs in any THE ANATOMY. MUSCULAR LAYERS 17 other family of Oligochaeta; but it does not seem to be too much to assume that they are really sense-organs, though their function must remain a matter of doubt. § 7. Muscular Layers. In nearly all Oligochaeta the muscular layers of the parietes are arranged in two layers. There is an outer circular and an inner longi- tudinal. It is a little difficult in so delicate a form as Aeolosoma to recognize that both these layers are present. The only exception to this rule seems to be the Enchytraeid genus Fridericia, where there are two separate layers of longitudinally running fibres (as well as the circular layer). In Lumbricus (see especially CERFONTAINE), the individual fibres of the circular coat form a layer of some thickness, variable, however, and particularly thin upon the intersegmental regions. The fibres are imbedded in a granular nucleated substance, and have a more or less strongly-marked columnar arrangement. The individual fibres are long and pointed at both extremities—a statement which applies to the muscular fibres of any part of the body—and longitudinally striate. This striation is apparently due to the presence of moniliform fibrils which makes up the substance of the fibre, and which sometimes give it a transversely striate appearance; these fibrils are imbedded in a clear interfibrillar fluid, which is often particularly plain in the axis of the fibre, giving it a hollow appearance. The ‘leech-like character’ of the muscular fibres of the earthworm was first pointed out by RatzeL, who, however, believed that only certain parts of the body- wall had muscles of this kind, whereas CERFONTAINE showed that they are general. The granular stroma in which the fibres are imbedded shows no cell outlines; it contains clear spaces which are probably the ‘lymphatic’ spaces referred to on p. 30. The longitudinal muscles of the earthworm form a layer of much greater diameter than the circular layer. In many species, as was first pointed out by CLAPAREDE (1), a peculiar bipinnate arrangement of the fibres exists. The individual fibres .appear to be attached on either side of a central rhachis formed by a septum of connective tissue. This peculiar appearance does not exist in all species of Lumbricidae, but it does occur in a few earthworms not belonging to that family. Upr (8) explained the appearance not as due to a series of connective tissue septa with fibres regularly given off on both sides, but as due to a@ series of compartments to the walls of which the fibres are attached all round. CeRFONTAINE proved, by histological methods more refined than those open to CLAPAREDE, that there is really no difference from the circular layer; similar fibres are imbedded in an identical granular stroma; the regularity of their arrangement, however, producing the appearance, wrongly interpreted by CLAPAREDE, is more marked than in the circular muscles, where, nevertheless, it exists. Here and there, and more particularly D 18 OLIGOCHAETA at the insertion of the septa, radial fibres pass along the ground substance and between the longitudinal fibres ; these often give rise to the appearance of regular septa. The aquatic Oligochaeta are, with the exception of Phreoryctes and Pelodrilus, characterized by the possession of a longitudinal muscular layer consisting of flat flakes or lamellae imbedded in a granular substance. These fibres, or rather plates, show no axial core such as occurs in the Lumbricidae and earthworms generally. In Fridericia, as already mentioned, there is in addition to the lamellae and super- ficial to them, a single row of fibres with an axial core. Hexssz has lately shown that in Fridericia all these muscles (circular as well as longitudinal) are constructed upon the Nematoid, not Hirudinean, plan. RatzeL had previously stated this of the fibres of the inner longitudinal layer. The development of the muscles in Rhynchelmis has been worked out by VEJDOVSKY. The mesoblastic cells which are to form the longitudinal muscles become spindle-shaped, and the muscular fibre appears within them ; the original protoplasm becomes entirely used up or nearly so in the formation of the fibre, while the nucleus atrophies. In the Lumbricidae (see VEJDOVSKY 9) there are two or three layers of cells which are converted into the longitudinal muscular layer. The muscular fibres appear first in the deepest cells, i.e. those nearest to the circular muscles; a considerable number of fibres appear in one cell. In the second and third rows of cells the muscular fibres are only developed at the sides; hence the pinnate arrangement in the adult. The cell boundaries are finally lost and the cell-substance remaining over after the formation of the fibres becomes the granular stroma lying between the fibres. The early stage in the development of the longitudinal muscles of Lwmbricus therefore represents the condition which occurs in Rhynchelmis. 2 The circular muscular layer has been generally put down as also a product of the mesoblast. It seems, however, fairly clear from the observation both of Bercu (8) and VesDovskY that epiblastic cells alone are concerned in its formation. On the other hand, in the regenerating tail of Lwmbriculus (see RaNDOUPH 4) it is stated that the circular muscles like the longitudinal are a product of the mesoblast. II. THe Nervous System. The nervous system of the Oligochaeta is formed upon the same plan as that of the higher Chaetopoda; the cerebral ganglia communicate with a ventral ganglionated chain by a circumoesophageal commissure—the entire cord lying in the body-cavity. In only one case is the primitive connexion of the cerebral nervous system with the epidermis retained. This occurs in Aeolosoma; in all the species of that genus which have been microscopically examined, the cerebral ganglia, though projecting into THE ANATOMY. NERVOUS SYSTEM 19 the body-cavity, are in connexion with the epidermis. In this worm—and it is quite unique among the Oligochaeta—the entire central nervous system is confined to the cerebral ganglia ; the ventral nerve cord appears to be entirely absent, except in Aeolosoma tenebrarum, where it exists in a rudimentary form in the shape of a few scattered cells. In all other Oligochaeta there are not only the cerebral ganglia connected by the circumoesphageal commissures with the ventral chain, but there is in addition a system of small ganglia arising from the cerebral ganglia, and concerned with the nerve-supply of the anterior section of the alimentary canal; in some forms also there is a ‘lateral line system.’ These various parts of the central nervous system may now be considered in detail. Cerebral Ganglia. These lie further forward in the lower than in the higher Oligochaeta; in the Tubificidae and the lower forms generally they are situated in the first segment; in the earthworms, almost without exception, they have moved back to the third segment; but the development shows that the former is the primitive position; they are moved back in the earthworms by the invagination of the stomo- daeum. In most, if not all, earthworms the cerebral ganglia mark the junction of the buccal cavity and the pharynx. Why it should be so is mysterious, but it is a fact that in the more highly organised Oligochaeta the brain is smaller and simpler than in the lower forms. In the latter—in the Tubificidae and Naidomorpha for example—the brain is not only relatively large, but it is provided with accessory lateral lobes, and is often prolonged posteriorly into posterior lobes. The form of the brain in these worms is often highly characteristic of the genus or species. Some references to the particular form of the brain will be found in the systematic part of this work. In Phreoryctes the brain has the simple bilobed character that is characteristic of the higher Oligochaeta to which this worm is related. The Lumbriculidae also have a simple brain. Among the Tubificidae there is often an impaired anterior median prolongation of the brain, which sometimes comes to be detached and remains in connexion with the brain by a nerve-cord. The formation of this anterior ganglion is highly suggestive of the buccal ganglia in the Mollusca. Special muscles are often attached to the brain in the lower Oligochaeta, which are apt to be confounded with nerves derived from it’, The cerebral ganglia give off a number of peripherally running nerves. The simplest arrangement of these again is found in the higher Oligochaeta—a fact which must, as it appears to me, be taken into consideration in fixing their position with respect to the so-called ‘lower’ forms. VrsJDovskyY only finds one pair in the genera Lumbricus and Criodrilus; Rosa figures an identical disposition for Hormogaster, and 1 They are attached of course to the connective tissue-sheath. D2 20 OLIGOCHAETA. Perrier for Puntodrilus; on the other hand, according to the last named author, Pontoscolex has two pairs of nerves arising separately from the brain, a pair of course on each side. SPENCER figures only one pair of nerves in Megascolides australis, which arise, as usual, near to the circumoesophageal commissures. Thus it appears general among the higher Oligochaeta for there to be only a single pair of cerebral nerves, which may however, and usually do, divide at once into two. I shall point out later, in describing the peripheral nerves given off from the ventral cord, the fact that there are there three pairs in each segment; one would suppose that there would be a corre- spondence between the cerebral ganglia and any one of the ventral ganglia, considering that they are developed as one continuous whole. As a matter of fact this correspondence exists, but it is masked by the origin of the third pair of nerves from the commissure, and not from the cerebral ganglia themselves. There is nothing extraordinary in this, for in the ventral ganglia one of the three pairs of nerves also arises from the commis- sural part of the cord. There is thus really a correspondence between the ‘ cerebral’ and the ‘spinal’ nerves. How for does this hold good in other groups? The most careful figures known to me of the nervous systems of the lower Oligochaeta are those of Vespovsky and of Stouc of the Tubificidae. In Ilyodrilus the latter figures three pairs of cerebral nerves, and also three pairs in each segment arising from the ventral cord. In Spirosperma there are four pairs of nerves springing from the cerebral ganglia, and also four pairs from the nerve-cord in each segment (?), one being commissural. In Monopylephorus, however, there does not, it must be admitted, appear to be the least correspondence. The cerebral ganglia are united with the ventral chains by the commissures which embrace the gullet ; from the commissures arise the visceral ganglia. Visceral Nervous System. This appears to occur in most, if not in all, Oligochaeta. In the earthworms it has been figured and described in Pontodrilus, Pontoscolex, Megascolides, Hormogaster, &c. I have never found it to be wanting in any earthworm where I have looked for it. It consists of either a solid mass given off from the com- missure or of a plexus having a similar origin; the plexus, however, is not entirely formed of nerve-fibres ; there are also ganglionic cells ; these branches of the visceral system ramify in the coats of the buccal cavity and pharynx. Among the lower Oligochaeta the same visceral nerves are met with; thus VEJDovsKY figures in Chae- togaster a pair of ganglia on either side of pharynx, which are connected with the brain. Other groups have the homologous ganglia, and reference must be made to VEJDOVSKY’S work for further details. Nerves of lateral line. In many Oligochaeta—and its occurrence is probably general—there is a nerve on either side of the body arising from the brain or from THE ANATOMY. VISCERAL NERVOUS SYSTEM 21 the oesophageal commissure, which has been compared to the nerve of the lateral line in fishes; it appears to consist especially of nerve-cells. This system of nerves has been described by VEJDoVsKY as existing in the Enchytraeidae, Phreoryctidae, Naidomorpha, Tubificidae, and Lumbriculidae?. Connected with it is a system of fine fibres which supply the walls of the alimentary canal; in Chaetogaster the oesophagus has a ring of nerve-cells round it, which are apparently referable to this system of intestinal nerves, which may fairly be compared with the Sympathetic system of Vertebrates. This nervous supply of the alimentary canal will not of course be confounded with the visceral nerves already described as arising from the circumoe- sophageal commissure. The lateral nerve itself or rather ganglionic chain originates from the epidermis, and remains in connexion with the same, the longitudinal muscles being separated where it occurs. Ventral Nerve-Chain. The commissures which arise from the brain and embrace the gut unite below it to form a ganglionated chain. This runs from end to end of the body ; in the extreme posterior region, where a regeneration of segments is going on, the ventral nerve-cord may be often seen to lie in the thickness of the epidermis ; otherwise it always lies in the body-cavity ; but VEsDovsky states that it is for the most part naked; that is, not covered by a continuous coating of peritoneum; scattered cells of the peritoneum are attached to it here and there. The nerve cord is usually enclosed in a muscular sheath, which may be, or is sometimes not, continuous right round it; but this nerve-sheath is derived from the same embryonic cells as those which form the cord itself. The cord may be divided into the ganglionic and the non- ganglionic or ‘connective’ part; the degree to which these are differentiated varies ; in Chaetogaster for instance, they are sharply marked off from each other in the figures given by VrsDovsky ; on the other hand it is the rule among earthworms for there to be only a slightly marked distinction; SPENCER even went so far as to practically deny, in the case of Megascolides, any difference in the whole length of the cord; but VEu- DOvsKY found constrictions separating the pairs of ganglia. In any case it seems certain that the ganglionic part of the cord fades gradually into the connective region, and the latter when present is of so short an extent that it is hardly recognisable. It is remarkable that the higher Oligochaeta should in this respect also show more primitive characters than the lower forms. The primitively double character of the ventral nerve-cord is partly retained for life in the genus Chaetogaster. In the Plates illustrating VesDovsky’s work upon the Oligochaeta there are several figures of the nerve-cord of this genus; it will be 1 Hessr however states that the supposed ganglion cells are only the non-modified protoplasmic portion of the ‘nematoid’ muscular fibres in Enchytraeidae and Naidomorpha. 22 OLIGOCHAETA seen that in Chaetogaster cristallinus the connectives uniting the first, second, third ventral ganglia are most distinctly double, the interspaces left being wide. The same holds good with the species Chaetogaster diaphanus ; but here the ganglia themselves are distinctly separated, which is not the case with the other species; each ganglion or each half ganglion is connected with its fellow by a short commissure which give to the anterior part of the nerve-cord a ladder-like appearance. For the remarkable specialisation of the nerve-cord in certain segments of Phreoryctes and various Enchytraeidae cf. under the descriptions of those families. The ventral nerve-cord gives off branches in each segment. These branches arise in two different ways; in the earthworms and in many of the aquatic genera they arise on either side of the nerve-cord and lie in the body-cavity for a greater or shorter distance until they plunge into the thickness of the body-wall. In -the Enchytraeidae, on the other hand, in Phreodrilus, and in many if not all Lumbriculidae, the two nerves are so closely applied to each other that they appear to be only a single nerve given off from the ventral side of the cord; this apparently single nerve plunges at once into the thickness of the body-wall, and then runs to right and left. This peculiar state of affairs has perhaps led some observers to abstain from figuring or to deny the existence of the branches of the nerve-cord; on a disséction of such worms as show this origin of the branches from the ventral surface of the cord no nerves would be apparent. In the Enchytraeidae judging from the figures of MICHAELSEN the unpaired character of the ventral nerves is the most marked; in Rhynchelmis, on the other hand, the two nerves, although lying close together, are quite distinct as two nerves. They are not present in the middle segment. In the Tubificidae and among earthworms the nerves arising from the ventral nerve-cord do not at once enter the ‘body-wall, but pass to a point at some distance from their origin before they enter the body-wall; the distance varies in different species; as a rule in those species with paired setae the nerves enter the body-wall near to the ventralmost seta; when this is further away from the median ventral line the nerves have a longer course through the body-cavity than when it is nearer to the median ventral line. The number of nerves given off in a segment varies considerably in different genera of Oligochaeta. In Lumbriculus and Rhynchelmis Vuspovsky could only find a single pair; three pairs is a much more usual number. This occurs for example in apparently all earthworms; it is figured for instance by PERRIER in Pontodrilus and Pontoscolex. In these and other earthworms the three pairs are not given off at equal distances from each other; two pairs are quite close at their origin; FRIfDLANDER has pointed THE ANATOMY. VENTRAL NERVE CORD 23 out, and I confirm him (for Perichaeta), that in Lwmbricus at any rate the two pairs of nerves which arise close together have a relation to the ventral nerve-cord, similar to that which the dorsal and ventral roots of the spinal nerves have to the spinal cord of most vetebrates ; the one in fact is situated more dorsally than the other. This state of affairs is remarkably distinct in certain species of Perichaeta which I have examined from this point of view. In Pontodrilus—in the segment which contains the spermi- ducal glands—there is a ganglion on one of these nerves, and just at the ganglion a branch arises which goes to the other nerve; this recalls the ganglion on the dorsal root of the spinal nerves of Vertebrates and the branch which immediately after unites this branch with the ventral root. Although there is this resemblance between all earthworms in the number and position of the branches of the ventral nerve cord in all earthworms, there is by no means a close correspondence between the various genera of aquatic Oligochaeta. Moreover accounts are apt to differ in many cases. For example, in' Tubifex Vespovsky figures no less than five branches of the cord in each segment ; D’'UDEKEM gives three as the number, while NassE only found two. ‘Stote figures five branches in Monopylephorus and Lophochaeta, two being dissepi- mental branches. I found three in Phreodrilus. There is not much information as to the course of the branches after they have left the nerve-cord; PERRIER carefully dissected out these branches in Pontoscolex ; he found that one only of the three branched considerably in the thickness of the body-wall. I found in the Perichaetid genus Diporochaeta a considerable branching of these trunks within the thickness of the body of the wall, resulting in fact in the formation of a nerve-plexus; on the other hand, I found in the same worm, and I have noticed similar appearances in other worms, that the branches arising from the cord were continuous right round the body, apparently joining dorsally. The histology of the nervous system is a large subject and one which can only be treated very briefly in the present work. It has been investigated by a large number of observers, including Vespovsky, Rurzius, FRIEDLANDER, ete. In transverse sections of the nerve-cord of Lumbricus, three dorsal tubes are very obvious; these ‘have received various names, and very various functions and homologies have been assigned to them. There is now no longer any question that these tubes, the ‘Neurochord,’ are of nervous nature; for they have been traced into connexion with nerve-cells; there are generally three of them; but occasionally four are present the tubes dividing and reuniting. These tubes in Rhynchelmis are developed out of a row of large cells which were formerly (and erroneously) regarded as being of mesodermal origin. The neurochord of the adult is single in the anterior segments and in the brain and the oesophageal commissures. In the middle and hinder part 24 OLIGOCHAETA of the body there are three tubes; these consist of a central nerve-fibre enclosed in a double sheath. The outer sheath has a few scattered nuclei in it and has a fibrous texture; the inner sheath has the same texture but fewer nuclei. The central fibre or rather bundle of fibres is the direct prolongation of certain large nerve-cells. The rest. of the nerve-cord is made up of fibres and cells; the latter are ventral and lateral in position. In the brain of course the conditions are reversed. The fibrous part of the nerve-cord consists of a more or less transparent ‘cytoplasm, the remains of a portion of the embryonic cell-mass; this in places forms transverse and longi- tudinal canals dividing up the meshwork of nerve-fibres into different regions. The fibrous mass is surrounded and the canals of the cytoplasm also, by a delicate sheath the ‘Glia sheath’; in this are a few nuclei; it appears to be of the nature of connective tissue and is not connected with the nerve-fibres. The ganglion cells are grouped into a medial and two lateral masses; the cells in Rhynchelmis are for the most part unipolar; only seldom are multipolar cells met with; in Lwmbricus CERFONTAINE figures multipolar and unipolar cells also. The development of the nervous system has been studied by KLEINENBERG, KovaALEvsky, WILSON, BERGH, VEJDOVSKY, etc. WILSON discovered, and the subse- quent observers confirmed him, that the cells which form the nervous system, like those which will form the nephridia, originate from a single cell on each side, placed near the posterior end of the body and termed a ‘teloblast’; continuous with this teloblast and forming a row of cells produced out of it is the layer which will ultimately become the nervous system; the teloblast is an epiblastic cell and there is therefore _ no doubt as to the epiblastic character of the central nervous system in the Oligochaeta. It appears to be entirely formed by the proliferation of these cells, and WILSon declares. that the cerebral ganglia are formed continuously with the ventral chain; it follows from the mode of origin just referred to that the ventral cord and the cerebral ganglia are a double formation, that the nervous system is bilaterally symmetrical; it has been held that it is a single formation laid down in one band. Bereu, while confirming WILSON, made the interesting addition to his facts that in the embryo there is a series of branched cells evidently of a nervous nature, which lie between the two nervous rows; Bereu thought, and Vespovsky confirmed him, that this plexus of cells and fibres is to be traced to the ventral epiblast and has no relation to the neuroblasts already referred to. Whether these cells have any relation to the definitive nervous system seems to be at present a matter of some doubt. VesDovsKy looks upon this primitive plexus as a remnant of the nerve-ring of the Medusa. The histological differentiation is so special a matter that I do not enter into it here. For details the reader is referred to VEJDOVvsKY’s work (9). THE ANATOMY. COELOM 25 III. Corom. The coelom in the Oligochaeta is invariably spacious and nearly invariably divided into compartments which correspond with the external metamerism. The division is effected by means of the intersegmental septa which are only wanting in Acolosoma; these septa are not as a rule applied to the parietes in such a way as to exactly correspond with the grooves on the exterior of the body that mark the segments ; hence the internal metamerism is not precisely as the external metamerism. The coelom is lined throughout by the peritoneal epithelium, which is reflected over all the organs that lie within it; from its wall are developed the gonads; it communicates with the exterior directly by means of the dorsal pores, and indirectly by means of the nephridia and the genital ducts. The coelom of the Oligochaeta is developed out of the paired mesoblastic masses which are formed early in the embryo; each pair joins its fellow in the mid-dorsal and mid-ventral line; but there is a nearly complete fusion above and below. No longitudinal septum remains to mark the division of each compartment of the coelom into right and left halves, and on the ventral side there is the mesentery supporting the ventral vessel only, which represents the ventral part of the line dividing the right and left halves. It has been stated that in Criodrilus the dorsal septum is persistent, but this appears to be an error. As a general rule, the coelom shows e no signs of division into ditferent cavities, except of course by the intersegmental septa; but this rule has a few exceptions. In the first place, the sperm-sacs and egg-sacs are undoubtedly portions of the coelom enclosed by special walls, which are set apart for the maturation of the sperm and ova respectively; these structures are dealt with under the description of the reproductive organs. In addition to these there are the remarkable sacs which envelop the gonads and the spermathecae in many Eudrilids, and which form so marked a character of that family. These sacs for the most part play the part of spermathecae, otherwise for the most part wanting in the family Eudrilidae, and they are dealt with under the description of the spermathecae. The lining membrane of the coelom varies greatly in its characters in different regions of the body; but it is nowhere ciliated, as is the case with other worms (e.g. the Archiannelida). The parietal layer is composed of flattened cells, the nuclei of which can as a rule be alone recognized in transverse sections; this epithelium can be demonstrated by the silver method with great success (see Power). CLAPAREDE too has figured the flattened coelomic epithelium upon the nerve cord, though, as already mentioned, Vrspovsky has stated the non-continuity of the coelomic E 26 OLIGOCHAETA cells upon the nervous system. The layer of peritoneum covering the alimentary canal is greatly modified, particularly upon the intestinal region. To this layer the name of ‘Chloragogen-cells’ was applied by CLAPAREDE. The layer was at one time thought to be a digestive gland; and the fact that the cells end in a finish thread which is closely applied to the wall of the intestine favoured the supposition. It was pointed out however by CLaParkpE that these cells are not so much connected with the intestine as with the blood-vessels upon its surface. According to KUKENTHAL their function is that of extracting waste substances from the blood and setting them free into the body-cavity whence they are removed by the nephridia. These chloragogen- cells contain greenish to blackish granules, the pigmentation being more marked in some species than in others. Upon the nephridia the coelomic epithelium often shows a different modification; the nephridia are of course always enveloped in a layer of this tissue as are all the organs lying in the coelom (except the gonads, which are peritoneum); but it is frequently a thin and barely discernable layer; this is not the case with the aquatic Oligochaeta; but those worms which appear to have the densest peritoneal layer round the nephridia are the Eudrilidae. The cells are often loaded with round granules of various sizes; the presence of these gives the nephridia, when viewed with the naked eye, a very conspicuous and white appearance. The coelomic cells which line the spermathecal pouches in the Eudrilidae are also very large; they are pear-shaped and are often apparently in a condition of rapid proliferation. It is quite otherwise with the cells lining the sperm- sacs and the ovisacs; in these sacs the peritoneal layer is but little conspicuous. The peritoneum, if it be really so, which lines the large spermathecal sac of Polytoreutus, has quite the appearance of a columnar epithelium. There is a further peculiar modification of the coelomic epithelium enveloping the remarkable calciferous glands of many Eudrilidae for which see the description of those glands. The coelomic cavity of the Oligochaeta also contains free corpuscles. In the higher Oligochaeta these are apparently of two kinds; there are small amoeboid corpuscles and large spherical corpuscles loaded with granules; in addition to the corpuscles there is also a certain amount of fluid which is coagulated by alcohol. The two kinds of corpuscles referred to are probably merely stages in growth; when the cell becomes loaded with excretory (?) products it naturally loses its activity of movement and assumes the spherical form referred to. Very remarkable are the elliptical corpuscles of the Enchytraeidae ; these have a fixed outline; sometimes there are round as well as oval corpuscles in the same species. In the lower Oligochaeta the corpuscles are often extremely abundant; this is particularly the case with the Enchytraeidae and the Naidomorpha; in the latter THE ANATOMY. COELOM 27 worms one would be disposed to put down the immense numbers of free corpuscles to the process of asexual reproduction with which their presence seems to be con- nected. But this will obviously not do for the Enchytraeidae, where there is of course no asexual reproduction’. Among earthworms there is generally not such a great abundance of corpuscles; but in many Enudrilids there is—a circumstance which gives to these species in many cases a milky white appearance (e.g. Megachaeta alba). In the embryos of Octochaetus I noticed a very large quantity of corpuscles, the presence of which may be related to rapid growth and excretion. ‘There are in most, if not all, Oligochaeta apparently the equivalents of phagocytes; these were first noticed by HorrMeister. Generally in the posterior region of the body are to be seen masses of brownish cells enclosing old and broken setae; the latter are evidently in the process of removal by disintegration; possibly this goes on until they can be thrown out of the body by the dorsal pores or the nephridia. § 1. Perihaemal spaces. Besides these chambers, formed by a sub-division of the eqelom, there exist others which for the most part involve various portions of the vas- cular system. The first structure of the kind to be described occurs in the Acanthodrilid Deinodrilus; in this worm the dorsal vessel is seen on a dissection to present an obscured appearance, which is due to the fact that it is enclosed in a sac which completely surrounds it and separates it from the general body-cavity. In this worm the dorsal vessel is completely double, and corresponding to this is a separation between the two halves of the ‘pericardium.’ In transverse sections, through the dorsal vessel, the sae in which each of the two trunks lies, is seen to consist of a very delicate muscular layer, which is covered externally and lined internally by a cellular coat; the external covering is formed of few and delicate cells; on the other hand, the internal lining consists of large cells, which are here and there heaped up into piles. At intervals delicate strands of muscular fibres pass from the walls of the sac to the contained blood-vessel, where they pass between the large chloragogen-cells which cover the blood-vessel and become lost in its muscular layer. This perihaemal space seems to commence a little way behind the head of the worm, but I have not fixed the actual point at which it commences, nor its connexion, if any, with the general coelomic space. SPENCER (1) subsequently recorded the presence in Megascolides of a similar sac enveloping the dorsal vessel ; in this case, however, there is a further complication. It possesses in fact a series of diverticula, one more dorsal, the other more ventral in position; these. diverticula—the dorsal ones especially as figured by SPENCER, are crammed with free and slightly attached cells; the main tube enveloping the 1 Cf. however Lemorne (2), by whom simple division is stated to occur. E2 28 OLIGOCHAETA dorsal vessel does not extend throughout the body ; ‘it is connected with the general coelomic cavity by a ventrally placed slit situated anteriorly, just where it narrows to pass through the intersegmental septum. The dorsal vessel is not the only vessel which is enclosed in a special perihaemal space; in the Eudrilid Libyodrilus, the two sub-intestinal vessels are enclosed in a space of the same kind ; two mesenteries arise from the ventral wall of the oesophagus, which meet below and shut off a space with a crescentic outline; in this space run the two vessels in question. For a part of their course the vessels are free in the interior of the space, further back they are attached to the walls of the space, and further back still they come to lie outside of them. The spaces in fact are each of them confined to a segment, and do not pass continuously from segment to segment. In the two closely allied genera Heliodrilus and Hyperiodrilus, the supra-intestinal vessel is in the same way enclosed in a coelomic space, distinct from the general coelomic cavity. As in the case of the dorsal vessel of Deinodrilus, the walls of the perihaemal space are connected here and there with the walls of the contained blood-vessel by delicate strands of fibrous tissue. The interspaces of these are filled with corpuscles. It seems possible that the function of these perihaemal spaces is concerned with the formation of the coelomic corpuscles; they were always found to be filled with corpuscles, and in more than one instance the corpuscles could be observed in the act of being budded off from the walls of the space. § 2. Other subdivisions of Coelom. A subdivision of the coelom only paralleled in the Polychaeta occurs in the genus Libyodrilus and in the aquatic Branchiura. In the former worm the two pairs of seta of each side of the body arise from the floor of a chamber which is cut off from the general coelomic cavity. There are thus a pair of chambers along the body like the parapodial chambers in certain Polychaeta. The membrane which forms the wall of these chambers is thin and presents no appearance of structure except externally, where it is covered by nuclei; the nuclei are on both sides; the membrane is continuous with the parietal peritoneum; the band of muscles uniting the two pairs of seta lies well below the membrane, which in section is seen to be somewhat, though not greatly, arched. Something of a similar kind occurs in the Tubificid Branchiura. Here the body at least in the posterior region is hourglass-shaped in transverse section; from the ‘waist’ of the hourglass a septum runs across the body-cavity transversely, dividing it into an upper chamber which contains the gut, and a lower chamber in which lie the nervous system and both dorsal and ventral blood-trunks. In addition to the coelomic tubes which have been described as surrounding some of the blood-vessels in certain Oligochaeta there is in AJllolobophora a ventral tube THE ANATOMY. COELOM 29 which VEsDOvsKY, who discovered it, compared to a lymphatic trunk; it runs on the ventral surface of the body between the intestine and the nerve-cord, and is of limited extent. All these tubular cavities are suggestive of lymphatic vessels. In the thickness of the body-wall there are often irregular spaces and clefts which are filled with corpuscles. Attention was first directed to these by KikenTHaL (1) who saw in them a fore- shadowing of the Vertebrate lymphatic system. They occur apparently in a good many different genera, but in none have they proper walls of their own; they are merely clefts and crannies left between the muscles. The branchiae of the genus Branchiura are hollow structures containing what I presume to be an extension of the coelom. This cavity however is traversed by anastomising fibres with nuclei at the nodal points; whether it is lined by a definite coelomic epithelium or not I am uncertain; the cavity is however shut off from that of the coelom by a muscular diaphragm which during life is in constant movement. It seems to be quite imperforate—to completely separate the coelomic and intra- branchial cavities. Very frequently this diaphragm was convex towards the body- cavity. If it were pulled out so as to form an ampulla lying in the body-cavity there would be a state of affairs comparable to that which is met with in the cephalic tentacles of Saccocirrus where MARIon and BopreTzsKy have described a cavity communicating with an ampulla lying in the body and have compared to the ampullae of Holothurians. § 3. Coelomic organs of problematic nature. Attached to the anterior septum of segments x. and xi. in Sutroa are two bodies suggestive at first sight of sperm-sacs. These are of a racemose form and are hollow; the cavity is however not single, but divided up by trabeculae into numerous subsidiary cavities. The walls are thin and apparently muscular. Enclosed within the meshes are many loosely packed cells. EIsEn first called attention to these bodies, but compared them to the albumen glands of Rhynchelmis. I could myself find no duct; and the fact that in cne case a diverticulum of the spermatheca lay within the sac led me to regard the cavity of the sac as coelomic. In certain Perichaetidae there are a series of minute paired whitish bodies lying one on either side of the dorsal vessel in the middle region of the body, and springing from the septa (in Perichaeta indica) or from the dorsal vessel itself (Perichaeta dyeri). These bodies are quite solid, consisting of a mass of cells surrounding a few muscular fibres. In Acanthodrilus fal landicus there are a series of similar bodies commencing at about segment xx. and continuing to the end of the body. They are attached to the septa near 30 OLIGOCHAETA to the nephridia and are not solid but hollow outgrowths of the septa; they are often rather racemose in form and are chiefly muscular with a lining and covering of cells. The opening of their lumen into the cavity of the segment in front of that which containg them is visible. CLAPAREDE has described and figured in the common earthworm solid masses of cells enclosing a few muscular fibres and depending from the septa. VEJDOVSKY states that similar bodies occur in Rhynchelnvis and Tubifex. He suggests that they are concerned with the growth of the septa. I found that the septal sacs of Acanthodrilus were rich in Glycogen. The structure of the septal sacs in this worm and in Sutroa is so like that of the sperm-sacs and egg-sacs that it is possible to see in them the remains of a segmentally arranged series of sacs out of which the sperm-sacs and egg-sacs were originally evolved. § 4. Dorsal Pores. The coelom is placed in communication with the external medium in a large number of Oligochaeta by a series of pores, one to each segment ; in addition to these structures which are called the dorsal pores there is in a certain number, most of the aquatic Oligochaeta, a single pore on the prostomium which is generally spoken of as the head pore. The two coincide in the same species in the genus Fridericia alone. The dorsal pores are never developed upon the first one or two segments of the body, and the point where they commence is characteristic for the species; in some forms for example the first one will lie between segments iv. and v., while in others the first pore lies altogether behind the clitellum. The dorsal pores were considered at one time to lead into sacs, the function of which was believed to be respiratory ; it is now known that the pores are simply perforations of the integumental layers just at the anterior boundary of the segment to which they belong; there is no lining of epithelium as has been erroneously stated to be the case; there is simply a discontinuity of the muscular and epidermic layers where the pores exist. The structure of these pores has been more particularly studied by UpE (8). In the figure which this author gives of a section through a dorsal pore there are represented a heaped up mass of peritoneal cells in the immediate neighbourhood of the pore; the function of this is very doubtful. Dorsal pores are not present in by any means all earthworms; they are absent for example in most of the Geoscolicidae, in many if not in all Eudrilidae, and in a few species of Acanthodrilidae and of other families ; among the lower Oligochaeta they are only found in a few species of Fridericia (Enchytraeidae). Their structure in the latter has been studied by VEsDovsKY and MICHAELSEN; in these worms the pore is bordered by large round glandular cells on each side; no such cells are visible in the case of the dorsal pores of earthworms. We are at present completely in the dark as to the morphological meaning of these pores. There seems to be no relation between them and any other organs; pores THE ANATOMY. COELOM 31 opening into the body-cavity from the exterior undoubtedly suggest nephridial organs; but no relations are apparent between the dorsal pores and the nephridia. The head pore is present in the Enchytraeidae, Naidomorpha and Lumbriculidae ; its position differs: sometimes it is at the very tip of the prostomium, sometimes at the junction of the prostomium with the buccal segment. A head pore has not been described in any earthworm. As to the function of these pores MICHAELSEN thinks that the head pore acts as a kind of safety valve to prevent undue pressure upon the brain when the movements of the body force an unusual amount of coelomic fluid into the anterior end of the worm’s body. The dorsal pores he thinks have the function of moistening the body and preventing its becoming unduly dry; it is certain that the coelomic fluid is pressed out through the pores; and their occlusion is regulated by longitudinal muscles which pass from the margin of one pore to that of the pore lying behind. SpENceR even thinks that it is used for the purpose of rendering the burrow of the worm sufficiently damp for it to move with comfort in; possibly some coelomic fluid is forced into the cocoon by the movements of the body when this is passed over the head. This latter function seems to be a likely one; the use of the coelomic fluid as a lubricant seems to be, so to speak, too expensive, especially when there are glands in the skin which appear to serve the same purpose. It is not impossible that there may be an analogy between the dorsal pores and the nephridia on the one hand, and the vertebrate kidney on the other. In the kidney there seems to be a purely filtering action at the extremity of the renal tubules and a secretory activity in the glandular section of the same tubes; perhaps in the Oligochaeta the dorsal pores pass out the waste fluids while the remaining excretory: products are elaborated and passed out by the nephridia. IV. NEPHRIDIA. The excretory organs of the Oligochaeta, to be treated of in the present section, will be termed ‘ nephridia’ after the convenient name introduced by LANKESTER?; the older name of ‘segmental’ organs—used by WILLIAMS, though it survives in many text books, is not so useful, since it tends to disguise the real nature of the organs in question; moreover the term ‘segmental’ suggests that they are always metameric in arrangement, which is not invariably the case; and that they are present in every segment of the body, which is also as far from being the truth. § 1. Eaxcretory organs in the embryo. Recent researches on the development of the Oligochaeta, particularly those of VrEsDovsky (9), have shown that at various 1 Notes on Embryology and Classification, Q. J. Micr. Sci. 1875. 32 OLIGOCHAETA periods in the life-history of these worms there are four sets of excretory organs; the very young embryo is furnished with certain epiblastic cells probably of an excretory function ; the older embryo has a pair of larval pronephridia; the older embryo a set of embryonal pronephridia, and finally there are the definitive nephridia of the adult; the terms used are those introduced by Vespovsky in his work already quoted (9). These various excretory organs will now be considered seriatim. (a) Eacretory cells. In the gastrula stage of various species of Lumbricus and Allolobophora there are a few large cells which are thus early set apart to perform an excretory function; so at least it is believed from the fact that they contain canals in their interior which are often coiled in quite a complicated fashion. They are epiblast cells distinguished by their large size and more granular appearance ; they always mark the anterior end of the embryo and only persist during the younger stages ; they do not exist in Allolobophora foetida, nor were they found in Rhynchelmis. There are three of these cells. But they get to be completely fused so that no cell-outlines, but only the three nuclei, are distinguishable. The canal appears to become lost in the primitive body-cavity, lying between the epiblast and hypoblast. When the cells are kept under observation the liquid contained in the canals is seen to be evacuated ; after this has taken place the canals are no longer visible, but the cell-boundaries come into view; for further details the reader must refer to VEJDOVSKY’s work (p. 208 et seq.). (6) Larval pronephridia. These were first seen by VEJDOvsKY in Allolobophora at a stage when the blastopore was still large: it is a fine canal running in the primary body-cavity. There are ultimately a pair of these tubes; these tubes do not exist in Rhynchelmis nor in Allolobophora foetida, but they are as described by BrRau (4) enormous in Criodrilus. The tubes are ciliated and open on to the exterior anteriorly ; in Lumbricus rubellus alone did Vespovsky find an internal ‘flame-cell.’ The organ opens on to the exterior through the lumen of the excretory cells; under the description of these the extension of that lumen into the primary body-cavity was mentioned. These tubes persist during the first formation of the embryonal pronephridia. (c) The embryonal pronephridia have no relation at all to the last, but they give rise to the permanent nephridia. These occur in every segment of the body, and the first pair open on to the exterior by the headpore of the embryo Lumbricus ; this first pair commonly occupy two segments and their lumen is not always ciliated. They are developed before the others, and disappear early, in a number of forms such as LIumbricus and the aquatic Oligochaeta. The name ‘headkidney’ has often been applied to this first pair, and they have been supposed to be different from the pairs which follow them. The principal difficulty in comparing them is the fact that the external pore is differently placed, being dorsal instead of ventral, and that they occupy THE ANATOMY. PRONEPHRIDIA 33 two or three segments. The latter fact is explained by VEsDovsky as due to the late appearance of the septum, which thus allows the nephridium to grow backwards. As to the first point, the apertures in question, though dorsal in Lwmbricus, are ventral in Rhynchelmis. There can be no doubt of the homology of the first pair of embryonal pronephridia in the two forms, and so the different position becomes a matter of sub- ordinate interest. Although the pronephridia of the first segment disappear in Lum- bricus, this is not universally the case ; I found that in Octochaetus nvultiporus the first pair of nephridia persisted and fusing with the next pair became the ‘ peptonephridia’ opening into the buccal cavity (see p. 46). The persistence of these nephridia in Octochaetus is of course an additional argument in favour of regarding the first pair of these organs in Lwmbricus and Rhynchelmis as equivalent to the pairs which follow and are converted into permanent nephridia. The following pairs of pronephridia in both Rhynchelmis and Lumbricus are short straight rows of cells without a lumen, but ending anteriorly in the case of Rhynchemis, but not of Lumbricus, in a‘ flame-cell’ provided with a long flagellum pointing backwards along the inside of the organ. These nephridia exist in the anterior segments of the body from which in the adult Rhynchelnis they subsequently disappear. In the Lumbricidae the pronephridia arise from a continuous string of cells (not proved in Rhynchelnis) ; this was first discovered by Wison, it having been previously found by Wuirman to hold good for the leech Clepsine. Wr.son’s results are so far confirmed by VEsJDovsky (9). This string originates from a single large cell, the nephridioblast ; the row of cells is called by VEsDovsKy the ‘nephridiostich’; traced forward this row is seen to break up into oblique rows of cells each surmounted by a larger one which is on the ventral side of the body. The large terminal cell of each ‘is the cell from which the funnel will ultimately be formed; but it never shows the vacuole with the contained flagellum which is to be seen in the corresponding stage of Rhynchelmis. From these pronephridia the permanent nephridia are developed; but before de- scribing the way in which this development takes place it will be convenient to cast a glance over the general anatomy of the permanent nephridia in the Oligochaeta. § 2. Nephridia of adult. Nephridia exist in all Oligochaeta. The only exception which there are good grounds to believe is really an exception in the Naid Uncinais littoralis; Bournz, who carefully studied this species (5), was unable, after repeated observation, to discover any trace of nephridia. Another peculiar condition of the nephridia has also been described by Benuam, and noticed by others, in certain Naids; in a few forms the nephridia are F 34 OLIGOCHAETA limited to one side of the body; with these exceptions all the aquatic Oligochaeta possess paired nephridia a pair to each segment; in all of these families, however, the nephridia are missing from a certain number of segments at the anterior end of the body. This state of affairs, however, is by no means confined to the Microdrili. It is met with in Pontodrilus, and the genera Glyphidrilus, Annadrilus, and Sparganophilus among the Geoscolicids; the actual segment in which the nephridia commence is a matter which varies; and as it is rather of classificatory interest, I refer to the description of species for more exact data. In the aquatic Oligochaeta— even if, as in the Lumbriculidae, the nephridia commence before the genital segments,— those segments never contain nephridia; in earthworms, on the other hand, nephridia are present in the genital segments, except in certain of the genital segments in the few species mentioned above as resembling the aquatic families in the want of nephridia in the anterior segments of the body. The nephridia are always much coiled tubes; and they always occupy two segments and two segments only’. The Fig. 5. NEPHRIDIUM OF MARIONIA SPHAGNETORUM. (After Michaelsen.) internal aperture, the funnel, lies a segment in front of that which bears the external pore. In the lower Oligo- chaeta the nephridia have no blood supply’; they are always covered by a layer of peritoneum, the cells of which are often very large. The nephridium of Psammoryctes barbatus will be selected as an example of a nephridium in one of the lower Oligochaeta; it is fully described and figured by VEsJDOVSKY (24, Pl. ix, fig. 1). The funnel which is composed of but few cells passes into a delicate spirally-wound tube decked with large clear vesicular peritoneal cells; this passes into a thicker walled section of a yellowish colour; this again passes into a clear walled tube which ends in a somewhat voluminous contractile bladder opening on to the exterior. In other aquatic forms the nephridia may be simpler; but the same regions are generally recognisable; not, however, in the Enchytraeidae whose nephridia (fig. 5) are very peculiar and resemble in many particulars the young developing nephridia of the higher Oligochaeta. A solid cellular mass, varying in shape according to the genus, is traversed by a coiled tube, the coiling of which again differs in different forms; from this arises a duct 1 Doubtfully excepting Plutelius. See also remarks on nephridia of Aeolosoma. ? Rhynchelmis is an exception (possibly other Lumbriculidae also) ; Vespovsxy has figured (9, Pl. xxvi, fig. 20) a bloodvessel following the coils of the nephridium. THE ANATOMY. NEPHRIDIA 35 which passes to the exterior and opens on to it through a small contractile bladder ; there appears to be no distinction here between the more or less glandular part of the organ in other Oligochaeta. Boxsius has lately discovered that the lumen is really a complex network. Among the Naidomorpha, the Lumbriculidae, and a few Tubificids, the funnel (totally absent in Aniphichaeta and Chaetogaster) is followed by an oval swelling coloured brown, and within which the nephridial tube appears to be branched and to form a small network; Vespovsky describes a network along the Fig. 6. NEPHRIDIUM OF LUMBRICUS. (From Benham.) a-h the narrow part of the tube partly ciliated. h-j ciliated wider tube expanding at C into ampulla. k-n. Wide tube. E, Muscular duct. I. Funnel. O. External orifice. ¢, Peritoneal layer. s, Muscular fibres. 7. Nucleus of cell, F. G. 2nd and 3rd loops of nephridium. course of the nephridial tubes of Chaetogaster; this matter will be referred to again in considering the more complex nephridia of the earthworms. The nephridium of Lumbricus. The most elaborate description of this organ is due to BenHam (9), whom we shall here follow. The nephridium is divisible first of all into two regions—one lying in the segment in front of that which bears F2 36 OLIGOCHAETA the external pore, which may be termed the preseptal portion; the other the much more extensive postseptal portion. The preseptal portion consists of the funnel and of a short tube passing through the septum. The funnel is made up of a considerable number of tall columnar cells, which are ciliated over their entire inner surface; the connexion of the funnel with the tube is effected in the following way: the tube has the usual intracellular Fig. 7. SEE Ae oe ps SSS AY See ml PI : - (7 ye (SZ La es CRISA . RE RRE SENS CBG TGA LEGER Cc’ NEPHRIDIUM OF LUMBRICUS ILLUSTRATING VASCULAR SUPPLY, (From Benham.) E. F. G. ist, 2nd, and 3rd loops of nephridium. N. Nerve cord. S. Septum. SN. Subnerval bloodvessel. v. Ventral bloodvessel. a. b. c, Branches of the same. d, Commissure uniting dorsal and subnervian vessels. ¢. f, Its branches, g. Dilatations on capillaries, s lumen; the two sides of this (in optical section) diverge at about the centre of the funnel, ‘each bending outwards, and then sharply backwards nearly parellel to its former course.’ The lumen ceases at the point of divergence, the cells being only grooved; the cells are continuous with the marginal cells already referred to. The centre of the horseshoe-shaped funnel has now to be accounted for; this has been THE ANATOMY. NEPHRIDIA 37 often figured as composed of a mosaic of numerous cells. It is, however, occupied by only a single large crescental cell. The ‘narrow tube’ which follows the funnel is the largest part of the whole nephridium ; the lumen is wide and of course intracellular!; here and there the lumen shows slight indications of branching. Cilia are not universally present, but there is an alternation of ciliated with non-ciliated tract. This is followed by the ‘ middle tube, which is of less extent and ciliated throughout: its calibre is greater and the walls are more glandular. The ‘wide tube’ commences with a wider dilatation where it communicates with the middle tube. This part is also very glandular, but not ciliated. The last section of the nephridium is formed by the muscular duct. This has apparently a lining of large cells, so that the duct is intercellular; it has numerous muscular fibres in the walls. This part of the tube opens directly on to the exterior. The actual course followed by the windings of the nephridium will be apparent from the illustrations and a special description is unnecessary. Nephridia of other Genera. LIuwmbricus is really the only genus of earthworms whose nephridia have been carefully studied from the point of view of their minute structure; there are, however, a few details to hand, which have been for the most part collected together in BENHAM’s paper. In all the earthworms with paired nephridia the same regions of the tube can be distinguished; but frequently there are differences in the relative development of the various parts. This is particularly the case with the terminal muscular section. In many genera of earthworms this section is very wide and large in proportion to the rest of the tube; especially is this the case for example with Acanthodrilus dissimilis and a few other species of that genus, and with Microchaeta, etc. Moreover, in the species named, the rouscular duct of the nephridium has a caecum given off near to its external pore; the presence of such a caecum is very common. On the other hand, there are a good many species which appear to be without the terminal muscular duct, or in which at any rate it is but slightly developed ; this seems to be especially the case with small forms; and it is perhaps a mark of degeneration; such genera as Gordiodrilus and its allies show an apparently complete absence of the muscular sac. The above remarks, it will be understood, refer only to the genera with paired nephridia; in those with diffuse nephridia the terminal sac seems to be invariably wanting. The funnel too shows a certain amount of variation; it is larger or smaller as the, case may be; in Rhinodrilus gulielmi 1 Vuspovsxy (9, p. 349, ete.) does not admit intracellular nature of duct ; he believes it to be intercellular throughout. 38 OLIGOCHAETA ¢ the funnels of the anterior nephridia are very large, and this condition is rather characteristic of the family Geoscolicidae ; it occurs also in Pontoscolex, where I have described it myself. In the last-mentioned genus the funnel is followed by a very wide section of the ‘narrow tube.’ The funnel varies in size in different worms, but in no earthworm with paired nephridia is it totally absent. The occasional branching, or rather the indications of branching, observable in the nepbridium of Luwmbricus have already been referred to; BENHAM has described in Microchaeta a complicated branching and anastomosis of the fine tube carried to such an extent that it formed a network round the other regions of the tube; more recently Rosa has met with the same thing in the genus Desmogaster ; in Hudrilus I have seen a certain amount of branching, but not so developed as in the genera mentioned. In all cases the nephridia of the higher Oligochaeta have an abundant blood supply; this runs of course in the peritoneum which invests the nephridia externally; the only genera in which this vascular supply is absent (or, at the most, feebly developed) are Ocnerodrilus and Gordiodrilus. The actual course of the vessels supplying the nephridium will be described under the vascular system. Specialization of nephridia. Another matter which is worthy of note in connexion with the paired nephridia is the specialization which is occasionally shown in different regions of the body. Among the Geoscolicidae it is common for a variable number of pairs of nephridia, occupying the anterior segments of the body to differ in structure from those which follow and occupy the rest of the body. The very first pair of all, in Rhinodrilus ecuadoriensis for example, but .also in worms belonging to other families, often appear to have acquired a different function for they open into the buccal cavity; but the consideration of these is deferred to a subsequent page. I am now concerned with those cases which may be exemplified by Microchaeta. In that worm the nephridia down to about the twenty-seventh segment are furnished with a long oval caecal appendage to the terminal sac. In the nephridia from the twenty-eighth segment onwards the terminal sac is larger and wider and is prolonged beyond the external orifice ; this prolongation corresponds of course to the caecum in the anterior nephridia, but it is hardly marked and is a continuation of the sac not being bent back upon it. In Acanthodrilus novae-zelandiae, one or two allied species, in Cryptodrilus fletcheri, and a few other earthworms, there is a very remarkable specialization of the nephridia, not connected as in Microchaeta with the cephalization of the anterior segment. There are in the worms now under. consideration two series of nephridia which open on to the exterior either in relation to the ventral or to the dorsal setae; but although there are two series there is only a pair of nephridia in each segment. THE ANATOMY. NEPHRIDIA 39 I speak of ‘two series’ because in the Acanthodrili at any rate the structure of the nephridium differs in relation to the varying position of its external orifice. When the nephridia open in front of the ventral seta they are provided with a very large caecum; on the other hand, the dorsally opening nephridia have either no caecum at all or the large muscular terminal sac of the nephridium is prolonged a little way beyond the external pore. Alternation in position of external pores. In addition to the worms just referred to, a curious condition of the nephridia has been described by Husrecur in the genera Lumbricus and Allolobophora'; the position of the nephridio-pores shows an alternation similar to that of the worms already described, but there is no change in the position of the nephridia themselves within the body, such as occurs in Acanthodrilus for _example. The bare fact of the alternation of these pores has been previously referred to by Boreti1; Borextii found that in a considerable number of different species this alternation from segment to segment was typical; the following is a list of these species :— Lumbricus rubellus, Hoftm. Lumbricus purpureus, Eis. Lumbricus herculeus, (Sav.). Allolobophora turgida, His. Allolobophora chlorotica, (Sav.). Allolobophora transpadana, Rosa. Allolobophora complanata, (Duges.). Allolobophora foetida, (Sav.). Allolobophora celtica, Rosa. Allurus tetraedrus, (Sav.). To this list others have since been added—for example Rosa’s Allolobophora tellinii. In fact it may be taken apparently that the typical arrangement for the genera Lumbricus and Allobophora is the one that has just been referred to. The position of the pores does not show precisely the same kind of irregularity that has been mentioned in Acanthodrilus. Bore.it found, and he has been confirmed by Husrecut, that the pores may either occupy the position that is generally assigned to them in the text-books, i.e. just above the second seta, or they may lie in relation to the fourth seta or finally between the fourth seta and the dorsal pore. Moreover there is no regularity in the alternation from segment to segment and not always 1 I can confirm from my own observations the accuracy of Husrecut’s statements and figures. 40 OLIGOCHAETA a symmetry of arrangement in the same segment; in the latter facts these genera recall the condition so characteristic of certain species of Acanthodrilus. Husrecut’s special contribution to this matter is his dis- Fig. 8. covery that when the nephridium opens in an ‘abnormal’ position the duct enters the body-wall as if it were going to reach the exterior immediately by the ordinary course; instead of which the tube bends to the left or to the right, as the case may be, and passing between the two muscular layers of the body-wall reaches its external orifice. The nepbridium itself retains the same position in the body-cavity wherever the external pore may be situated; on a mere dissection it would be impossible to say of any one particular nephridium where the external pore was placed. The tube as it passes along the body-wall lies so exactly between the circular and the longitudinal layers of muscle that the appearances presented suggest at first sight merely a break in continuity of the body-wall along this line, due to a defect in the section; this may possibly, HuprecuTt thinks, have caused other cases similar to this to have escaped the attention of observers; at any rate there is no doubt that so far as our ACANTHODRILUS DISSIMILIS. 8. Setae, x. Nephridiopore. present knowledge goes a similar state of affairs has not been described in any other genera than those mentioned. These facts have led HuBRECHT . to suggest, though very tentatively, another theory of the variations of the nephridia in the Oligochaeta. s It will be remembered that there are certain Cryptodrilids in which three pairs of nephridia are met with. HuBREcHT indicates that the three positions which the nephridiopores occupy in many Lumbricidae may possibly be a reminiscence of the original presence of three pairs just as it has been suggested that the alternation in Acanthodrilus may be a trace of the former existence of two pairs of nephridia in the immediate ancestors of this genus. The same arguments that apply in the one case apply in the other. Diffuse nephridia. The nephridia are among those organs of the Oligochaeta which show most variation. For a long time it was thought that they agreed with other segmented worms in possessing a single pair to each segment of the body, a variable number of segments being without nephridia at all. It is now known that this state of affairs is by no means the only way in which the excretory system is developed. A very large number of genera are largely or entirely characterised by possessing THE ANATOMY. NEPHRIDIA 41 a nephridial system of a different kind. Prrrizn first called attention to the peculiar character of the excretory system of Perichaeta, which he described in the following words: ‘Les organes segmentaires sont ici trés rudimentaires, ce qui concorde avec labsence d’orifice extérieur attribuable & ces organes. This statement was made of Perichaeta posthuma; and later of Perichaeta robusta he wrote, ‘Les organes segmentaires, sous forme de tubes extréimement délicate, sont adhérents aux cloisons, ou disséminées sur la membrane péritonéale que tapisse la cavité générale’; further on, in the part of his paper devoted to a general resumé of the anatomy of the group, he speaks of the nephridia forming a ‘réseau glandulaire, which appeared to him to be an indication of an incomplete suppression of these organs. In a communication addressed to the Royal Society of London-(10), I pointed out that in Octochaetus multiporus there were more than a single pair of nephridio- pores to each segment of the body; and that in the interior of the body the nephridia were divided into eight tufts in each segment, corresponding with as many external pores. In a later paper (47) I corrected the number, having found a much larger number of orifices. The next statement upon the subject was by BennAm, who found in a species of Perichacta a large number of small and separate nephridia. He referred in this paper to my own simultaneous discovery of a similar condition in another species of that genus. These results were published later; I showed that in one species of Perichaeta there. were a large number of external excretory pores, perhaps a hundred or so in a segment; later still the funnels of these were discovered. My results and those of BENHAM were confirmed by Spencer for a large Cryptodrilid from Australia—Megascolides australis; but Spencer, in addition to the network of small tubes with many external pores, found in the posterior segments of the body a series of larger tubes with funnels not. possessed by the smaller tubes. Since these various papers were published a large number of species of earthworms have been described which possess an excretory system of this type, which has been called by myself ‘diffuse’ and by Benuam ‘plectonephric’. It characterises some or all of the species of the following genera (those in which all the species have a plectonephric excretory system are marked by an asterisk): Perichaeta*, Megascolex*, Octochaetus*, Deinodrilus*, Plagiochaeta*, Benhamia*, Trigaster*, Cryptodrilus, Megascolides, Digaster*, Microdrilus*, Dichogaster*, Typhoeus*. All these genera, it will be noticed, are members of three families—Perichaetidae, Acanthodrilidae, Cryptodrilidae, which I unite here into one super-family Megascolicidae. In no other worms is this condition of the nephridial system met with, though I shall point out later, some Eudrilids are provided with an integumental nephridial network which is somewhat analogous. & 42 OLIGOCHAETA The naked eye characters of the exeretory system of this kind are very obvious; the absence of the large paired tubes cannot be passed over, and the delicate ramifying tubes especially attached to the septa can hardly be missed, at any rate in well- preserved specimens; very often these tubes are massed into the semblance of paired nephridia, three or more pairs to a segment; this is often seen among the Acantho- drilidae; in the Perichaetidae, on the other hand, the network is more diffuse and MEGASCOLIDES. (After Spencer.) A portion of execretory system of two segments. 1. Nephridial tube in body-wall. 2, Funnel. 3. Septum. 4-6. Nephridial tubes cut in various directions, 7. External pores. not broken up into separate masses. In Mega- scolides and also in Megascolex armatus the diffuse network of minute tubules is reinforced by the existence of larger paired tubes, one pair to each segment. These large paired nephridia appear to be in connexion with the smaller tubes. In Octochaetus there seems to be no connexion from segment to segment of the nephridia, though the nephridial mass of, at any rate, each side of each segment forms a perfectly continuous net- work ; there are no funnels in the anterior region of the body, and the external pores are not so numerous as they are in Perichaeta. In the hinder region of the body the nephridia are also, as will be described more at length presently, connected with the gut; and the excretory system of this part of the body differs from that of the more anterior segments in two points: in the first place ‘there are funnels, and in the second place there is no question at all about a network which is most clear; I have figured this network (58), which often becomes so close that the inter- Spaces are mere trabeculae of limited extent, traversing a kind of excretory sinus; the net- work in the anterior part of the body has rather to be inferred; I have never actually seen a branching of the tubules, but as the orifices to the exterior are numerous, and as there is nowhere any break of continuity, a network must exist; in any case there is no doubt whatever about its existence,in the hinder end of the body. The tubes which lead to the exterior often branch in the thickness of the body-wall, and often run THE ANATOMY. NEPHRIDIA 43 for some distance in its thickness before opening on to the exterior; in this case they generally run between the two muscular coats. In Perichaeta the nephridial tubules are of finer calibre than in Octochaetus ; and they are furnished with funnels, which are especially obvious in the anterior region of the body; in this region, apparently in all true Perichaetae—it has at any rate been commented upon by many observers—the nephridial mass is much thicker than posteriorly ; the septa are here covered with a thick almost furry coating of tubes, which in sections are seen to leave but little of the available coelom free; further back the nephridia are by no means so obvious, a fact which has led to their being described as absent by myself (in Megascolex coeruleus for instance); in poorly preserved earthworms they would not been seen by anyone who was not already informed of their existence and therefore unprepared for their excessive minuteness. I have already mentioned that to BeNHAm belongs the credit of having first discovered the existence of numerous minute nephridia in a species of Perichaeta; from his account it would appear that in this species the several nephridia are quite distinct from each other; this does not seem to be the case in all the species of this genus; in Perichaeta bermudensis, for example, it seemed to be undoubtedly the fact that there was a connexion between all the nephridial tubes of a segment, and that in addition to this there was a connexion between the nephridial plexuses of following segments; the tubes were followed through the septa ; they appeared to pass into the plexus of the segments in front and behind. The exact arrangement of the nephridial tubes is very difficult to follow on account of their smallness and complicated course, but at any rate SPENCER’s investigations into the anatomy of the excretory system of Megascolides led him also to the conclusion that there was a connexion from segment to segment. That there are numerous external pores is a matter capable of being easily proved; if a bit of the cuticle be stripped off, the pores can be easily seen, particularly in specimens which have been preserved in corrosive sublimate; the pores, although small, are far from invisible; it is a matter of interest that there seems to be no regularity in their arrangement; there is no trace of any metameric disposition. The segmentation so clearly visible in most of the organs of the worm’s body has here been lost. The minute structure of the nephridia in those worms which have an excretory system of the diffuse type has been chiefly studied by Spencer (1) and myself (45, 47). Some details about the funnel are to be found in Bennam’s paper already referred to. As Benuam has pointed out, the nephridia of Perichaeta evidently consist of the three regions described by himself in Lwmbricus ; in Octochaetus only two kinds of tubes are to be found. G2 44 OLIGOCHAETA In all of these worms there is no muscular sac at the points of opening on to the exterior; favourable sections are wanted in order to demonstrate the actual pores, since the tubes are of narrow dimensions up to the very opening. Generally speaking, the cells of the epidermis show some peculiarities at the orifices; in Perichaeta I have figured the conditions which are found; and Spencer has figured them in Megascolides. The epidermic cells become slightly narrower and converge round the actual orifice, forming possibly a kind of constrictor for regulating the outflow of secreted matter. As already mentioned, the funnels may be present or absent in the diffuse nephridia ; when present they do not seem to differ at all from those of the paired nephridia, except that they are generally smaller. Benuam has carefully described the funnel in Perichaeta malamaniensis; there are eight or nine marginal cells, but no central cell nor any centrifugal gutter-cells; the intracellular duct of the tube appears to open at once into the midst of these cells. I have, however, described a horseshoe- shaped funnel in Perichaeta bermudensis. Nephridia of this kind do not exist in any of the aquatic Annelids, nor have they been met with in any other groups of Annelids excepting only the leech Pontobdella, where BouRNE has stated that a network exists and is continuous from segment to segment; this statement, however, has been denied. Integumental nephridial network. The network that exists in certain Eudrilidae is not, I believe, morphologically comparable to the diffuse nephridial system already treated of. This condition of the nephridial system appears to characterise a large number of Eudrilidae, and I have attempted a classification of that family partly based upon the presence or absence of the network. It has been studied most thoroughly in the genus Libyodrilus. That worm, like all the other genera of the family to which it belongs, has paired nephridia—a pair to each segment. But the duct leading to the exterior, instead of passing at once to the exterior, branches and forms a complicated network in the integument; in this worm the peritoneal layer which lines the body- wall is, in places at any rate, excessively thick; and in this layer tubes formed by the branches of the ramitied external duct run; these put into communication the nephridia of successive segments. The actual details of the way in which this complex network is formed are perhaps subject to some variation. It appeared to me, however, that there were four principal and longitudinally running trunks, symmetrically disposed two on each side of the nerve-cord (corresponding in position to the setae); from these branches arose which ramified in every direction through the longitudinal muscular layer and finally joined a circular vessel running right round the body between the two muscular coats. From this latter fine branches lead to the exterior. These tubes are nowhere ciliated and seem to be not comparable to the coelomic THE ANATOMY. NEPHRIDIA 45 network of Perichaeta, etc., but to be a branching of the epiblastic duct of the nephridium. The duct of the nephridium of Allolobophora is said by VEsDovsKy (9) to branch in the integument, and I have already referred to the way in which that duct runs for a considerable distance between the two muscular coats before opening on to the exterior. In some few of the genital segments it seemed to me that the paired nephridia in Libyo- drilus were absent, but that the net- work was present. One cannot help being reminded by these facts of the excretory system in the Nematoda and ‘the Acanthocephala; in both these groups the excretory system seems to occur in the shape of tubes running in the integument; the Lemnisci of the Acanthocephala (and an homo- logous structure has been described in certain Nematodes) are processes of the body-wall occupied by a quantity of tubes which are doubtless of an ex- LIBYODRILUS INTEGUMENTAL NEPHRIDIAL NETWORK. cretory nature. Eliminate the paired nephridia of Libyodrilus and the re- Pk 1. Dorsal blood-vessel, 2. Supra-oesophageal blood-vessel. Maiming par t of the excretory system 3. Infra-oesophageal blood-vessel. 4, Ventral blood-vessel. would be exceedingly like that of the &Nevirtion, Que of Initio nts of int two groups of worms referred to. To a certain extent I have followed the development of the excretory organs in Libyo- drilus ; the integumental network is, as one would suppose, a secondary development ; the first part of it to appear is a continuous longitudinal duct on each side connecting the nephridia of following segments. I imagine that VEJDovsKy is correct in regarding the longitudinal duct connecting the nephridia of Lanice conchilega (described by Meryer' and Cunnincuam?) as formed out of the terminal epiblastic part. of the nephridia—the ‘ bladder’ of the nephridium of Lwmbricus—which have become fused together ; it is therefore of some interest to note that a similar single connexion is first developed in Libyodrilus. The fabulous (?) connecting duct of Polygordius is perhaps of the same nature. The genera Megascolex and Megascolides—probably others will be discovered when 1 Quoted by Lang in his monograph on the Polyclada in Fauna u. Flora des Golfes von Neapel. * On some points in the Anatomy of Polychaeta. Q. J. Mier. Sci. vol. xxviii. 46 OLIGOCHAETA the finer anatomy of earthworms is better known than it is at present—are in their excretory system to some extent intermediate between the Megascolicidae that have just been described and those in which the nephridia are paired; there is a network of fine tubes, but in addition to this a pair of larger nephridia which have a funnel opening into the segment in front of that in which the tube lies; a more remarkable intermediate condition exists in those Cryptodrilidae which I place in a separate genus Trinephrus, the name being suggested from the fact that they have three pairs of nephridia in each segment of the body; at present, however, the finer anatomy of these worms is unknown, and we do not know the exact structure of these ne- phridia; a second intermediate condition is offered by the Geoscolecid genus Brachy- drilus. In this worm there are two distinct pairs of nephridia in each segment of the body. Finally, we have those forms in which there are only a single pair of these tubes and they form the majority; they include all the aquatic families, the Lumbricidae, the Geoscolicidae (except Brachydrilus already referred to), all the Eudrilidae -(where, however, there is an integumental plexus to be referred to), and many of the Megascolicidae, the following genera (those genera in which all the species have paired nephridia are marked with an asterisk): Diporochaeta*, Perionyx*, Acantho- drilus*, Cryptodrilus, Megascolides, Ocnerodrilus*, Gordiodrilus*, Pygmaeodrilus*, Pontodrilus*, Microscolex*. Connexion of nephridia with the alimentary canal. There are among the Oligochaeta various organs of a glandular nature, opening into the alimentary canal, which in some eases are certainly, in others probably, more or less modified nephridia. These organs are invariably connected with either the front or the hind end of the canal; that is to say, they never communicate with that section which is undoubtedly of hypoblastic origin. At the same time it cannot be said with absolute certainty that those sections of the gut into which they do open are either stomodaeum or proctodacum ; unfortunately embryological data are at present too scanty to permit of a definite statement upon the point. In the present section I shall only deal with those glandular appendices of the alimentary tract which are certainly, or very probably, of nephridial nature; I deal later with such organs as the calci- ferous glands which cannot, with either probability or certainty, be referred to that category. 1. Peptonephridia. I accept BeNHaAm’s term for nephridia opening into the anterior section of the alimentary canal; it seems probable that their function is in relation to that of digestion. Such organs occur in more than one family of the Oligochaeta. They were first made known in the Enchytraeidae, and THE ANATOMY. NEPHRIDIA 47 have since been described in the Acanthodrilidae, Eudrilidae, Cryptodrilidae, and Geoscolicidae. In the Enchytraeidae they are the so-called salivary glands, which have been described by VrsDovSKY, MICHAELSEN, and others; in certain species of this family there are a pair of tubes which are more or less branched, opening into the alimentary canal behind the pharynx ; sometimes the apertures are lateral in position, sometimes they are dorsal and ventral respectively. The principal reason for considering these tubes to be of nephridial nature is their minute structure; they have a lumen which is undoubtedly intracellular; it is, however, necessary to be careful not to be too much influenced by a consideration of this nature; the calciferous glands, for example, are in some worms folded in so complicated a fashion that the lumen becomes intracellular; the lumen of the blood-vessels is also intracellular; it has been shown that minute vessels are formed by the canaliculisation of cells (by LANKESTER in the Leech). The salivary glands of the Enchytraeidae, however, differ from nephridia in having no opening into the coelom; there is not the least trace of a funnel. Perhaps this fact is not of first rate importance as an argument against their nephridial nature; but it must be considered. Moreover the tubes are not ciliated; this again is against any homology with nephridia; in no Oligochaetous worm are there nephridia’ which are entirely without cilia; it frequently happens that a greater or less section of the nephridia is devoid of cilia; but the non-ciliated area is restricted. The segments which are occupied by these salivary glands are devoid of other nephridia; this, at first sight, suggests the metamorphosis of the missing nephridia into the salivary glands; but it must be remembered that in the Enchytraeidae, as in most other of the lower Oligochaeta, the nephridia are defective in the anterior segments of the adult worm. On the whole, it seems that the nephridial or non-nephridial nature of the salivary glands of the Enchytraeidae must be left an open question. It is quite otherwise with those earthworms in which similar salivary glands occur. The first description of nephridia opening into the anterior part of the alimentary canal in an earthworm was by myself in Octochaetus multiporus; in this worm there are lying along the pharynx a pair of tufted organs which end in a duct of some dimensions; this duct runs forward and opens into the buccal cavity ; here again one objection to the nephridial nature of these glands is the fact that they do not appear to be furnished with any coelomic pore. This statement, however. only applies to the glands in the adult worm. Fortunately in this particular instance the development has been traced and I have found that these compact glands are really formed by the fusion of at least two pairs of nephridia which are at first distinct and each provided with its own coelomic funnel. There 48 OLIGOCHAETA is in fact no room for doubt that these ‘salivary glands’ in Octochaetus nvultiporus are nephridia, modified doubtless to perform some function other than that performed by the nephridia in the other segments of the body—though physiological observations are wanting as to what this function is. In Rhinodrilus ecwadoriensis BENHAM has described the first pair of nephridia as somewhat different in appearance from the remaining organs and as opening into the buccal cavity. Such glands also occur in Acunthodrilus annectens and in its near ally Acanthodrilus paludosus. In certain earthworms there are a pair of large nephridia occupying the first two or three segments of the body, which appear to resemble those of Octochaetus already described ; such glands occur in Pontoscolex (see woodcut), where they were originally termed by Perrier ‘glandes & mucosité’; I showed that these organs are undoubtedly nephridia; they do not, however, actually open into the gut, but so near to it that when the anterior segments are, as is occasionally the case in this worm, inverted, the orifice is actually sheltered by the inversion. These glands cannot be really distinguished from the ‘ peptonephridia’ of Octochaetus, etc. SPENCER described in the Australian Megascolides australis a number of fine tubes opening into the buccal cavity, which are clearly nephridia ; in that worm the nephridial system is of the diffuse kind; and the tubes lying in the anterior section of the body open into the buccal cavity. The difference between the condition which characterises this worm and that found in OUcto- PONTOSCOLEX CORETHRURUS. . * . fikpceie siesta chaetus is simply that there are numerous openings g.c. Cerebral ganglia. b. Buccal cavity, instead of only a single one on each side. It seems p.h. Pharynx. @. Ocsophagus. g.a. First yeasonable to suppose that the two organs are referable nephridium (‘glande & mucosité’). 0.9. . External orifice of same. 0.8, Second to precisely the same category. Curiously enough the nephridium. 2. Nervecord. /. Vacuities ee 5 in muscular layer for implantation of Same presence of numerous nephridial tubes opening si into the buccal cavity occurs in the Eudrilid Libyo- drilus ; in that worm there is a fine network of tubes in the walls of the buccal cavity, opening here and there into the interior of that cavity. In all these cases it will be observed that the nephridia which are connected with the anterior part of the alimentary canal show precisely the same modifications as the nephridial tubes which are not so connected, but which open directly on to the exterior. There are in both cases paired and diffuse nephridial tubes. There can be no doubt, it would seem, that the buccal cavity of these tropical earthworms, like THE ANATOMY. NEPHRIDIA 49 that of Lumbricus, is stomodaeum ; hence there is nothing remarkable in the fact that nephridia open into the buccal cavity instead of the exterior, for the buccal cavity is morphologically external. In the case of Octochaetus the correspondence is even clearer; for in that worm the massive Peptonephridia, though they only possess a single aperture apiece into the buccal cavity, open also on to the exterior of the body and as in the case of the nephridia of the succeeding segment by numerous pores. The development, however, happens to show that it is the openings into the buccal cavity which are the primitive openings, the numerous external pores being secondary. The relationship of the modified anterior nephridia to the ‘head kidney’ of the embryo has already been dealt with. 2. Anal nephridia. Not only are there undoubted nephridia connected with the anterior end of the alimentary canal; but in one species of Oligochaeta there are undoubted nephridia connected with the rectal region. In Octochaetus multiporus I found that a few segments at the posterior end of the body are filled with a dense mass of nephridial tubes which open both directly on to the exterior and into the rectal part of the gut; I am not, however, certain as to whether this part of the gut is or is not proctodaeum. On the whole, the facts which I was able to get together as to the development of this part of the nephridial system seemed to show that the section of the-gut into which they open is not proctodaeum; on the other hand, probability seems to urge that it is. A remarkable fact about these anal nephridia in Octochaetus is, that they are provided with numerous coelomic funnels. Elsewhere the nephridial system of this Annelid is not in the adult provided with funnels ; the tubes form a branching network, very easy to demonstrate as a network, which communicates from segment to segment and also communicates with the exterior through numerous pores upon the integument; there is thus a direct communication between the interior of the alimentary canal and the exterior through the nephridia; the nephridial tubules, when they approach the lumen of the gut, open into wider passages, which have a lining of cells precisely like those of the gut; it would appear that these latter are really diverticula of the gut, though here again the actual development has not been worked out. The occurrence of these nephridia opening into the gut is interesting when they are compared with the respiratory trees of Bonellia and its allies among the Gephyrea. I have also suggested a possible resemblance to the Malpighian tubes of the Arthropoda. The comparison here would be of course with the terminal wider tubes with an intercellular duct into which the actual secretory portion of the tubes open. So far as it is at present known Octochaetus multiporus is the only Oligochaet which possesses anal nephridia. 50 OLIGOCHAETA § 3. Development of permanent nephridia. The development of the permanent nephridia out of the pronephridia has been followed by Vespovsky (9) in Rhynchelmis and in various species of Lumbricidae. In the former genus the postseptal part of the pronephridium gets thicker and a lobe (woodcut, fig. gl) is formed which lies to the side; the distal part of the pronephridium remains unaltered ; in this condition the nephri- dium recalls that of the Enchytraeidae. The pronephridiostom, originally consisting of one cell with a flagellum, becomes multicellular, ultimately consisting of eight cells; these become ciliated and the long flagellum vanishes ; but it coexists for some time with the cilia. The vacuole of the pronephridiostom becomes the cavity of the funnel, which comes to open into the coelom and the tube following is gradually excavated. The last part of the permanent nephridium to appear is the epidermic, con- tractile, terminal bladder. Occasionally in the course of development secondary funnels appear, a course of development which recalls the formation of many funnels in some of the ‘plectonephric’ worms. In the Lumbricidae the distinction between the pronephridium and the nephridium is not so marked because of the absence of the vacuole and the flagellum in DEVELOPMENT OF NEPHRIDIA OF the pronephridiostom ; but in these worms, as RHYNCHELMIS. in Rhynchelmis, the main part of the permanent (After Vejdovsky.) organ appears as a lateral outgrowth of the The stages are numbered consecutively. gl Lobe pronephridium ; the original straight tube lead- forming chief part of Nephridium. ing to the exterior remaining more or less unaltered, the alteration concerning the formation of a hollow tube out of it. It has been said by Berau that there is no epidermic invagination to form the contractile bladder of the nephridium of Zwmbricus ; but this is denied by Vespovsky. There is evidently a greater break between the pronephridia and the permanent nephridia in Rhynchelmis than in Lumbricus. This is emphasised by the existence of the flagellum in the former. THE ANATOMY. NEPHRIDIA 51 The development of nephridia of the plectonephric type has been investigated by myself in Octochaetus multiporus. There is no doubt that the numerous nephridial tufts of the mature worm with their numerous openings on to the exterior are produced by the growth of a paired series of organs, which, as VEJDOVsKY thinks, are probably the equivalents of the pronephridia of Lumbricus. These paired nephridia, however, are provided with well-developed and ciliated nephrostoms ; and in their course they are much coiled upon themselves before reaching the external pore. The first pair are anomalous from the very earliest stage in which I studied them. They occupy at least two segments as does the ‘head-kidney’ of other species, and they open, not on to the lateral body surface but into the commencement of the stomodaeum. A little later in the course of development these first pair become fused with the second pair and the pore is more definitely within the stomodaeal cavity, from which a tubular outgrowth appears to have DEVELOPMENT OF NEPHRIDIAL TUFT OF MEGASCOLIDES. (After Vejdovsky.) 3, Funnel. 2, Septum. 3. Nephridial tufts in various stages. 4. Connecting tubes finally (4a) degenerating. arisen to meet the duct of the nephridium. Thus the * mucous gland’ of the adult worm is a compound structure representing two nephridia of successive segments. The funnels of all the pairs of pronephridia, at first functional, degenerate later ; the cilia disappear and the row of cells which forms the funnel becomes more than a single cell thick. The lumen of that part of the nephridium also which immediately follows the funnel vanishes and a solid string of cells is left. ‘The development of such nephridia has also been studied by VEsDovsxKy (4) in the Australian earthworm Megascolides australis. There appears to be no doubt that in this species there is (see accompanying woodcut) to begin with a pair of nephridia to each segment ; these have a funnel and from the funnel leads a straight duct not perforate ; here and there the cells become larger and finally form loops; these loops ultimately increase in size and become complicated coils, the connecting part of the original tube H 2 52 OLIGOCHAETA degenerating into a mere strand of connective tissue. The last step is the absolute severance of the connexion. ‘Thus it appears firstly that the nephridial system of this worm originates from a pair of pronephridia to each segment; and that this becomes broken up into a large number of nephridia of which one only, the large nephridia described by SPENCER, retains the funnel. If there is, as has been described by Spencer, a plexus formed by the interconnexions of the small nephridia it must be secondary; but at any rate it is noteworthy that at first when the several nephridia are in course of formation out of the pronephridium there is a connexion at least between the numerous nephridia of the same segment. As to the continuous longitudinal ducts described by SPENcER the most careful search failed to show them in the embryo; they also must therefore be secondary structures. § 4. Phylogeny of excretory system. The facts just detailed concerning the development of the plectonepbric system might appear at first sight to argue for the theory that this condition is secondary and that the paired nephridia of Lwmbricus, &c. are to be looked upon as the primitive condition. The facts seem to negative my view, supported by SPENCER and BENHAM, that the paired nephridia of the majority of Oligochaeta are formed by reduction from a network such as now exists in Perichaeta and many other genera. Before any developmental facts were known this course of evolution seemed to be supported by many considerations. In the first place a progress from a more generalized to a more specialized condition is seen in the evolution of other organs. Then there are certain resemblances between the network nephridia and the excretory organs in the Platyhelminths. Traces of the supposed primitive condition also existed in those worms which are now provided with the paired form of excretory organ; thus in Anachaeta the nephridium has occasionally more than one funnel; in many forms there is a branching and anastomosis of the fine tubes of the nephridium, for example in Microchaeta, to which reference has already been made, and in other forms also. This view must evidently be now given up; but, on the other hand, it is not by any means permissible to adopt the converse view already suggested. It does not follow that the diffuse nephridia are the outcome of a branching and specialization of the paired nephridia; on the contrary the developmental facts absolutely disprove this. What they do prove is that both paired and diffuse nephridia are formed out of similar pronephridia; that in fact both kinds of excretory organs are equally ancient. This opinion, practically arrived at by myself after the study of the development of Octochaetus, was more definitely formulated by VeEspovsky (9). THE ANATOMY. ALIMENTARY CANAL 53 It is clear too from the fact that the diffuse and paired form of the excretory system occur in forms which are so nearly related, for instance in Acanthodrilus and Octochaetus, that there can be no profound gap between the two kinds of organs. The ‘Plectonephrica’ of Bennam I agree with VEsDOVSKY in considering an artificial group. V. ALIMENTARY CANAL. The alimentary canal in all Oligochaeta consists of a straight tube running from the mouth which opens on to the first segment and is. overhung by the buccal lobe! (when present) to the posteriorly situated anus; with two exceptions the anus is surrounded by the last segment of the body. These exceptions are Criodrilus and Sparganophilus ; in the former worm VesDovsky figures (24, Pl. x, fig. 21), seven post- anal segments, and the anus itself as dorsal in position. There is, however, no flexure of the intestine in Criodrilus; it passes, as in other Oligochaeta, perfectly straight from the mouth to the anus. Developmentally the alimentary canal of the Oligochaeta, as of other animals, consists of three portions: (1) Mesenteron, hypoblastic in origin, (2) Stomodaewm, (3) Proctodaeum, both formed by later invaginations of the epiblast ; of the two the proctodaeum is the later formation. The greater part of the alimentary canal is of hypoblastic origin. The actual extent of the stomodaeum seems rather doubtful. VxEspovsky, who at one time thought that the end of the pharynx marked its posterior limit, was subsequently inclined to think that the buccal cavity only was of epiblastic origin in Lumbricus and Rhynchelmis. In the adult worms the alimentary canal may be divided into the following regions: mouth and buccal cavity, oesophagus, pharynx, and intestine. The mouth is nearly invariably ventral in position? and it leads into the buccal cavity which is of limited extent; the buccal cavity of the Enchytracidae is often provided with one or a pair of small tongue-like organs which spring from its floor. These are probably sense organs. MICHAELSEN at one time put them down as playing the part of a sucker. These organs are furnished with minute hair-like processes, and appear to be entirely cellular; they are in fact a product of the lining epithelium of the buccal cavity; in some species they can be everted; in a few species the buccal cavity has a dorsal diverticulum in which the cells are more glandular ; this state of affairs occurs in Benhamia, in Microdrilus and a few more species In the higher Oligochaeta the buccal cavity is separated from the ensuing pharynx by a constriction on which lies the cerebral ganglia; in Aeolosoma there appears 1 A few exceptions where the intestine is spiral are noted under the description of that organ. 2 Terminal where the prostomium is absent. 54 OLIGOCHAETA to be no buccal cavity at all but the mouth leads at once into the pharynx. The latter has usually exceedingly muscular walls, the musculature being dorsal; the lumen is folded and ciliated, in the lower Oligochaeta, and dorsally, as Benuam has lately pointed out in the earthworms—at least in many earthworms. In Perichaeta the buccal cavity is markedly capable of extrusion; to a less extent this is also. the case with other Oligochaeta. The pharynx, on the other hand, is not to be extruded. After the pharynx comes the oesophagus; this is a tube of moderate calibre which extends through a varying number of segments. The oesophagus is always ciliated in the lower Oligochaeta but not throughout its whole extent in the earthworms; the cilia usually begin after the calciferous glands, if these are not present in the hinder region of the tube; thus in Lidyodrilus the cilia begin in segment xiv. The oesophagus is the most specialized part of the alimentary tract in correspondence with the cephalization exhibited by the other organs which lie in the anterior region of the body. The pharynx is often supplied with glands which have been variously termed ‘salivary glands,’ ‘septal glands’; they are not to be confounded with ‘salivary glands’ of apparently nephridial origin which are treated of under the excretory system. The septal glands (at one time mistaken for ganglia of the visceral nervous system) are especially conspicuous in the aquatic Oligochaeta, where they are attached to the septa, whence of course the name; they are masses of pear-shaped cells, each cell being prolonged to form its own duct; the ducts appear to enter the pharynx. VEJDOVSKY has figured very obvious glands of this kind in the embryo Allolobophora. These septal glands seem to me to be simply epidermic glands which have been invaginated along with the stomodaeum ; they are appended to a part of the alimentary tract which must be, though the actual proof is in most cases wanting, of epidermic origin; in this case the glands will be entirely comparable to those which open on to the genital papillae of the Perichaetidae, or in fact to the glandular cells of the clitellum. On the other hand their position upon the septa and lying freely within the coelom seems to be against this interpretation, and in favour perhaps of regarding them as homologous with the septal sacs of certain species of Perichaeta and Acantho- drilus referred to above. Gizzard. In the majority of the Oligochaeta a part of the oesophagus is modified into an organ which is usually called the gizzard; this part of the alimentary canal is distinguished by the immensely thickened muscular walls and by the thick chitinous layer secreted by the lining epithelium. As to the muscular layer, it is the circular fibres which are especially increased. The gizzard is absent in a large number of Oligochaeta, particularly among the mud-living forms; in no family of Oligochaeta THE ANATOMY. ALIMENTARY CANAL 55 which habitually live in or at the bottom of streams, lakes, etc. is the gizzard present; this fact might, and indeed has, led to the inference that its absence is to be accounted for by the soft nature of the food. Probable though this hypothesis is, it seems to be contradicted by the fact that. the gizzard is also absent in a number of terrestrial Oligochaeta whose food is presumably quite the same as that of other terrestrial species which possess a gizzard. Moreover a gizzard is wanting or rather represented only by a rudiment in a species whose habitual food is harder than that of any other Oligochaeta ; in Pontodrilus bermudensis, which lives on the sea shore in coral debris (with which its alimentary canal is always full) there is only the trace of a gizzard. Microscolex too is a purely. terrestrial form but it either has no gizzard or a degenerate one. It is evidently therefore not safe to lay down any such general statement about the cause of the presence or absence of the gizzard. In the greater number of earth- worms the gizzard only occupies a single segment; but the segment in which it is found is not always the same; in Lumbricus, for example, the gizzard is usually in the xviiith segment; in Megascolex, on the other hand, the vith segment is occupied by this organ. Very often there is more than a single gizzard; when this is the case the gizzards are in consecutive segments; the genera Digaster and Dichogaster have been so named on account of the presence of two gizzards; there are two gizzards also in Benhamia and three in the genus called by FLETcuHEer Perissogaster—a genus which is in the present work included in Digaster. In the genera Moniligaster, Pleionogaster, Hyperiodrilus, Heliodrilus, and one or two others, there are a considerable number of gizzards—three to ten in number. The genus Perichaeta is remarkable for the fact that it is provided with only a single gizzard, which nevertheless occupies two segments. It seems to be quite possible that in this case there are really a pair of gizzards which have become ‘intimately fused so as to form a single one. An important point to be noticed about the gizzard is that it may occur in any segment or segments of the oesophagus; it has no fixed position except of course for the species or genus as the case may be. As to the histology of the organ, comparative researches are as yet wanting. It is perhaps remarkable that the muscular tissue which enters into its formation is ‘precisely similar to that of other parts of the body and not striated; it so often happens that the muscular tissue of organs of great muscular power is made up of striated fibres that the negative fact—that this is not the case with the Oligochaeta— is worth calling attention to. Calciferous glands. — Appended to the oesophageal region of the digestive tract of many Oligochaeta are a series of glands which have been variously termed 56 OLIGOCHAETA ‘Glands of Morren,’ ‘Oesophageal glands,’ ‘Calciferous glands, etc. The oesophagus in the higher Oligochaeta is usually divisible into two tracts, of which one is more richly supplied with blood-vessels than the cther and has a more folded lining epithelium. Frequently this part of the oesophagus is constricted by the septa, and the sections of the tube which lie between the septa are broader than those which are nipped by the septa; hence a moniliform appearance often exists. This is the case for example in the genus Perichaeta (s.s.). The specialization of a tract of oesophagus having these characters in a more pronounced fashion is characteristic of the genus Onychochaeta and of other forms; in the genus mentioned that portion of the oesophagus which occupies segments xii. to xv. is wider than elsewhere and is provided with markedly regular and deep folds of epithelium; this is a step in advance towards the existence of distinct diverticula of the oesophagus such as exist in a great many genera and species; it is at the same time merely an exaggeration of the vascular tract of oesophagus commonly found in the higher Oligochaeta whether they possess or do not possess distinct calciferous glands. In Octochaetus multiporus the oesophagus is swollen in segment xvii. ; in transverse sections of these swellings they are seen to be really diverticula of the oesophagus opening into it by wide apertures on either side. In Pontoscolew the three pairs of ealciferous glands first investigated by PERRIER are only attached to the oesophagus by their duct on either side; they are otherwise quite separate from it; every stage in fact appears to exist between mere dilatations of the oesophagus and diverticula of it; in the most differentiated form of the calciferous glands, such as are found for example in Pontoscolex, the pouch communicates with the gut by a distinct duct whose walls are lined by cells different in character from those which line the gland ; it is commonly the case that this duct has a lining of ciliated cells while the cells of the gland itself are not ciliated. We shall return to a more detailed description of the minute structure of these glands later; at present we are concerned with their distribution in the group. Calciferous glands in some form or other have been found in the following families ; those families in which they are nearly or quite universal are printed in capitals; those in which a good many forms are without such glands are printed in clarendon ; finally, italics denote that the glands are rarely met with in the family. LUMBRICIDAE. Cryptodrilidae. GEOSCOLICIDAE. Perichaetidae. ACANTHODRILIDAE. Eudrilidae. Enchytraeidae. THE ANATOMY. ALIMENTARY CANAL 57 In all the remaining families of Oligochaeta there are no recognizable traces of these glands or of anything that can be compared to them; they are absent in fact in the following :— Aeolosomatidae. Phreoryctidae. Naidomorpha. Lumbriculidae. Tubificidae. Moniligastridae. It will be seen that the presence or absence of glands appended to the oesophagus is broadly indicative of an aquatic or a terrestrial life; it is by no means absolutely so; for Moniligaster is, so far at any rate as is at present known, a purely terrestrial type, much more so than is the family Eudrilidae of which many members are largely aquatic in habit. There appears, however, to be a much closer relation between the presence of calciferous glands and comparatively large size and complex organization. This generalization is trammelled by fewer exceptions. Certain exceptions will at once occur, notably perhaps the smaller species of Benkamia which are among the smallest, if not the smallest, of earthworms ; it must, however, be borne in mind that this genus Benhamia is not typically composed of small-sized species; on the contrary the average size is large, and some of the biggest earthworms are referable to the genus Benhamia. The smaller genera of a given family have frequently a reduced number of calciferous glands. This is best exemplified by the genera Ocnerodrilus and Pygmaeodrilus, in which there are but a single pair of these glands; so too in Kerria among the Acanthodrilidae and Gordiodrilus a genus of somewhat doubtful affinities; the Geoscolecid Ilyogenia has but one pair of glands, and is withal a small member of its family. In fact it seems that everything points to a decided relation between size and absence or presence of calciferous glands. The relation may be more accurately stated thus :— Calciferous glands are absent or reduced in number in genera which are entirely composed of small-sized species. When the entire family contains only small-sized genera calciferous glands are completely absent. It has been asserted that the presence or absence of these glands is in accordance with the nature of the food of the worm; the Limicolae of CLAPAREDE are, as their name denotes, mainly dwellers in soft mud or among weeds, and thus contrast with the boring earthworms. This view, however, does not seem to me to be consistent with the facts. A greater knowledge of the life habits of the Oligochaeta may perhaps reveal some relation between the two series of facts, but at present this knowledge does not exist. 58 OLIGOCHAETA A further indication that there is a relation between the glands and the size of the worm where they occur is afforded by the simplification in structure which the glands show in the smaller Oligochaeta. In Ocnerodrilus the lumen of the single pair of glands is but slightly divided up by folds projecting into the lumen; glands of this worm have been figured by myself and by Ersey. In Gordiodrilus there is a similar simplicity in the minute anatomy of the single unpaired oesophageal pouch found in the worm. The calciferous glands are limited to the oesophagus; nothing at all resembling them occurs in the intestinal region—except possibly the ‘kidney-shaped glands’ of Megascolex coeruleus and of Typhoeus (see below). These latter however are not known to produce calcareous particles such as are secreted by the calciferous glands; a difference of function which this implies is not of course an objection to a serial homology; and it is also true that both oesophagus and intestine are derivatives of the mesenteron. It seems however to be clear that the folded structure of the intestinal glands is not comparable to the folded structure of the calciferous glands, for the latter is simply an expression of the fact that the glands in question are diverticula of the already folded lining membrane of the oesophagus, while the epithelium of the intestine is not folded ; hence the complication of the intestinal glands is an independent formation. The calciferous glands vary in number from one to eight pairs; they are nearly always in consecutive segments, but these segments are not fixed. Thus in Pontoscolex the glands are in segments vi.-viii., while in Benhamia they occupy segments xiv. xv. xvi. asa rule. It seems that after the first segments of the oesophagus any segment is capable of developing calciferous glands. These organs are not always paired. In the Eudrilidae and in the genus Gordiodrilus there are median unpaired glands which have the structure of calciferous glands; in Buchholzia there is a median dorsal gland. A remarkable fact about the unpaired glands of the Eudrilidae (as seen for example in the genera Hudrilus, Polytoreutus, and Heliodrilus) is that they coexist with paired glands ; this does not however mean that the two glands are in the same segment, but they are so far independent that there is sometimes a break of a segment between the last unpaired pouch and the single pair of calciferous glands. These unpaired glands of the Eudrilidae were first discovered and described by myself in the genus Ludrilus (62). To these structures MicHarLsen has given the name of ‘Chylustaschen.’ He is of opinion that their function is different from that of the paired calciferous pouches. The ‘Chylustaschen,’ according to MICHAELSEN, are organs not of secretion but of absorption ; by their epithelium nutritive matters are supposed to be taken up from the blood. Here again a difference of function does not by any THE ANATOMY. ALIMENTARY CANAL 59 means necessarily imply a morphological difference; and MicHarLsen is far from suggesting directly any such difference ; the fact however that he gives them a different name would perhaps lead to the inference that there was some difference of structure ; MIcHAELSEN does not in his descriptions of the minute structure of these glands (12) show any differences of importance from the paired calciferous glands of the Eudrilidae and of other Earthworms; there is however a difference which I have noticed and described in Heliodrilus and Hyperiodrilus ; in these two genera, and in all probability in others, the periphery of the glands is occupied by a network of tubes whose lumina are intra-cellular; the rest of the gland shows only inter-cellular lumina. This is however in my opinion not a matter of great importance; the excessive folding of the epithelium of the pouch becomes at length so complex that the lumen inevitably becomes intra-cellular, the folds get to be smaller than the length of a single cell; this at least is my explanation of the matter. As to the supposed difference of function—it does not exist in every case—I have found that in Hudrilus the unpaired glands secrete calcareous particles entirely similar to the particles secreted by the paired gland, and so has UDE (4). There are so many instances among the Oligochaeta of organs being paired in one genus and unpaired in another, that a difference of this kind cannot be looked upon as of much importance ; the various parts of the generative apparatus are sometimes unpaired, though as a rule paired; the contrary occurs with the dorsal vessel which is as a rule unpaired, but occasionally paired ; even the brain is more or less completely divided into two halves. The actual fact as to the paired or unpaired character of the glands is not therefore in my opinion a matter for serious consideration in deciding upon their homology. We may fairly regard them as structures which are serially homologous. These organs, the paired and the unpaired, consist of a diverticulum of the oesophagus, which is lined by epithelium continuous with that of the oesophagus ; as a rule this epithelium is rather different in appearance from that whence it has been derived; the minute structure of the glands has been studied in Lumbricus (CLAPAREDE, 1), Pontoscolex (PERRIER, 5), Ocnerodrilus (BEDDARD, 20, and Eisen, 1), Eudrilus (BEDDARD, 62), Heliodrilus (BEDDARD, 54), Alvania (BEDDARD, 89), and in a few other types; Ocnerodrilus is the least complicated of these. In that genus the single pair of glands have a capacious lumen which is only moderately divided up by internal folds; the cells lining the diverticula are ciliated, as are those of that part of the oesophagus at least which follows the apertures of the glands into it. Among the Eudrilidae the subdivision of the lumen by numerous anastomosing folds has reached its highest point; and here as in many other species the epithelium is not ciliated; in Pontoscolea the epithelium is remarkable for being a low flattened epithelium ; it is 12 60 OLIGOCHAETA elsewhere columnar. In the genus Pontoscolex and in most other genera each of the three or more pairs of glands opens by its own separate orifice into the oesophagus. Lumbricus (including Allolobophora) is an exception to this statement; in that genus, as was at first pointed out by MarsHaty and Hurst in their ‘ Practical Zoology,’ the first pair of glands alone open into the lumen of the gut; the two following glands of each side open into each other and into the lumen of the first pair; there is thus but a single orifice into the gut for all three glands; this difference has been emphasised by terming the first pair of glands oesophageal pouches in contradistinction to oesophageal glands. The descriptions of MaRsHALL and Hurst have been confirmed by KuLaain (1). One other genus at any rate shows the same thing exactly ; I have found that in Microdrilus there are three pairs of glands of which the first pair only open into the gut; the remaining two of each side open into the first. A curiously analogous arrangement was found occasionally to exist in Polytoreutus; MicHAELS=N discovered that in a specimen of Polytoreutus coeruleus the last of the unpaired glands opened not directly into the oesophagus, but into the pouch in front. An example of the calciferous glands of this type, which are, it will be observed, not distinctive of any one family, is afforded by Octochaetus multiporus (see Plate V). In the young just ready to leave the cocoon the glands, which are most conveniently studied in that condition, owing to their small size, form merely a dilatation of the oesophagus. In a series of sections commencing at the head end of the worm the gland comes into view lying above the oesophagus and between the two dorsal vessels; the latter immediately come to lie upon it. Still passing back, the gland gradually extends round the oesophagus opening into it at first in the dorsal middle line, afterwards along other lines. Ultimately the openings into the oesophagus become so frequent that the latter can be no longer distinguished from the surrounding gland; its somewhat more columnar epithelium passes gradually into the lower cubical epithelium of the gland. Only on the ventral surface can the oesophagus be said to exist apart from the gland for there are no ventral folds of the glandular membrane. The entire gland is covered with a layer of peritoneum of which the cells are not so long and pear-shaped as elsewhere. The lining epithelium is arranged in numerous folds some penetrating further towards the lumen than others and being generally thicker at their free edge owing to the fact that the cells are here more columnar. Peripherally the cells are ciliated. The secretion produced by these glands is in the form of solid particles of calcareous matter; the actual form in which these concretions occur varies somewhat. In Lumbricus they are figured and described by CLAPAREDE as being ‘small perfectly spherical bodies with a diameter of from 2-6 micromm.’; in optical properties they THE ANATOMY. ALIMENTARY CANAL 61 resemble, according to the same author, fat particles; besides these round particles which constitute what is called by CLaparkpE ‘ Kalkmilch,’ there are in the first pair of these glands rhomboedra, and larger concretions are figured but not specially described. These latter show radial striations. The large concretions as well as the small spherules are figured by LanxesterR. In Pontoscolex PERRIER mentions only the fine spherules. In Microdrilus I have found rhomboedral crystals and also in Ludrilus. That these particles are formed of carbonate of lime seems to be proved by the fact that they dissolve in acetic acid, giving off carbonic acid. Besides the glands already described there are other diverticula of the oesophagus which seem to be the equivalents of the calciferous glands, but are of different structure from those described and from each other. The Enchytraeidae have been known since the careful investigations of VespovsKY (8) and MICHAELSEN (1-4) to possess glands appended to the anterior part of the alimentary tract which have been termed by MIcHAELSEN ‘ Chylustaschen, and regarded as homologous with the similarly named structures in the Eudrilidae; these occur in two varieties :— In Buchholzia there is a single dorsal pouch from which arises the dorsal blood- vessel; this pouch communicates with the oeso- phagus by a wide orifice; its interior is however not a simple lumen but is occupied by a mass of tubules or by a single much convoluted tubule, which has the appearance of a nephridial tubule, inasmuch as it has an intra-cellular lumen; the interspaces between the tubules is occupied by blood spaces ; from these arises the dorsal vessel; this apparently single pouch is really composed of two closely BUCHHOLZIA. CALCIFEROUS GLAND. a a 3 ‘ Jiated, applied pouches; its lumen is not ciliate (nee areas In Fridericia leptodera there is a pair of — ,, peritoneal layer. 2,3. Tubules of gland 4. . : : “1: + : : Dorsal vessel. 5. Lumen of intestine. 6. Ventral diverticula with ciliated lining epithelium, vaeel, qq Patonaaw, &; >: (Mancalde Wnt ep and in Henlea ventriculosa two pairs of such _ thelial layers of intestine. 12, Vascular sinus of diverticula; the degree of folding of the aie lining epithelium varies somewhat. These structures are obviously related to the diverticula of earthworms, but it is not so certain whether the remarkable glands of Buchholzia are. The latter are to some extent paralleled in another genus, Gordiodrilus; in the four or five species belonging to this genus there opens into the oesophagus on the ventral side an ovoid pouch. This pouch is formed in the first place by 62 OLIGOCHAETA a diverticulum of the oesophagus; round the epithelium, which is columnar, is a layer of tissue in which no cell boundaries could be detected; abundant nuclei scattered throughout it appear to show that it is a mass of cells; these cells are filled with oval or round particles like those which occur in the peritoneal cells in many parts of the body, particularly upon the nephridia. This mass of tissue is not separated from the epithelium by any membrane of any kind; the epithelium rests directly upon it; it is traversed in various directions by blood-vessels; towards the blind end of the pouch this layer gets thinner; at this end the lumen of the gland becomes intra-cellular ; the periphery of the gland in fact is formed of a network of tubules exactly like nephridial tubes, but they are not ciliated, so far as I have been able to discover. It is a question as to whether the mass of cells covering the lining epithelium is peritoneal or is a specialization of the lining epi- thelium; JI believe the latter interpretation to be the right one; as to the peripheral network of fine tubes I recur to the matter later. These glands or gland—for GORDIODRILUS. CALCIFEROUS GLAND. they may be paired or unpaired— 1. Lumen. 2. Nephridium apparently in connexion with gland. @re very different in many points 3, 4. Septa, The blood-vessels and the vascular plexuses are shadett. from the cal ciferous glan ds of earth-worms or from the pouches appended to the gut in the Enchytraeidae. They are perhaps best to be compared with a series of structures which characterise certain Eudrilidae. In the systematic part of this work I divide the Eudrilidae into two groups, in one of which there are calciferous glands and three unpaired pouches of the same structure ; in the remaining set the place of these is taken by a greater number of paired bodies, closely applied to the oesophagus. These glands were first described by myself in the genus Hudriloides; they have also been found in Stuklmannia and a few other genera. They consist of a mass of tissue exactly like that which surrounds the lining epithelium of the pouch in Gordiodrilus; this mass of tissue likewise surrounds a lumen which opens into the oesophagus (in Eudriloides at any rate) ; this lumen, however, is of very limited extent; it does not nearly traverse the whole THE ANATOMY. ALIMENTARY CANAL 63 of the glands, but ends very soon. The mass of cells surrounding it appears to be white in the dissected worm owing to the immense amount of minute spherical particles ; the cells are in places specialized, and get a certain resemblance to columnar epithelium; this alteration takes place round a blood-vessel; the effect produced is that of a gland tube cut across, the lumen of which is filled by blood; the tissue in these modified tracts stains deeply with borax carmine; elsewhere it is hardly at all stained by that re-agent; this is of course due to the absence of secreted particles which are so abundant in the non-staining regions. I shall again recur to these glands in connexion with the blood glands of the Oligochaeta. Whatever the function of these glands may be, it does not appear to be exactly that of the calciferous glands of other Oligochaeta, for calcareous particles were never found in the lumen of the glands. They seem, however, to be in all probability serially homologous with calciferous glands; I never found the two kinds of glands to co-exist in the same species; and the glands now under consideration are clearly diverticula of the oesophagus as are the true calciferous glands. I believe that the mass of cells which surrounds the feebly developed epithelial lining is peritoneum, which has increased in amount part passu with the gradual reduction of the glandular secreting surface, and has changed the function of the organ. Apart altogether from function, which is not now the question, these glands must from their position, and from the fact that they are diverticula of the oesophagus, be referred to the same category as the calciferous glands of other Oligochaeta. Intestine —The oesophagus widens out to form what has been called the large intestine ; the exact segment at which this begins varies a good deal; it is earlier or later as the case may be; as a rule in the more simply organized forms it is more anterior than in the more complex species. The large intestine not only differs from the oesophagus by its greater calibre, but by various details of structure, not always, however, present. The most characteristic feature is the typhlosole; the typhlosole is a median fold of the dorsal wall of the gut, which projects into its interior and diminishes the lumen while it increases the secretory surface. The degree to which the typhlosole is developed varies greatly; in the lower Oligochaeta it is entirely absent; it is also absent in a few of the more simple terricolous forms such as Ocnerodrilus. It has been often stated to be absent in Perichaeta; as far, however, as my experience goes, it is not absent in that genus, but very feebly developed, forming a slight fold which projects for but a short distance into the lumen of the gut. The complications in the typhlosole vary in different species ; in Octochaetus it is a fold which reaches nearly to the ventral surface of the gut and is trifid at the free edge; an equally deep fold exists in Deinodrilus 64 OLIGOCHAETA benhami, but it is not trifid. At a varying distance from the anus the typhlosole ceases; 1 have figured its abrupt ending, in the Acanthodrilid Octochaetus multi- porus. After this point the term rectum may be applied to the gut. The large intestine is generally a straight tube running without a bend from commencement to termination; in a few forms, however, it has a spiral arrangement ; this is seen in Plagiochaeta, and, according to Horst, in Pontoscolex corethrurus. In the course of the tube it often exhibits a specialization into several regions; in Meguscolex coeruleus this is especially evident—perhaps to some extent on account of the large size of the worm rendering the various regions more evident than they would be in a small species. In the first six segments the intestine is deeply pouched; in the twenty-second segment the pouches became deeper still; they extend to about the seventy-sixth segment; in several Oligochaeta the intestine commences in this way with a series of deepish pouches; for instance, in Urobenus brasiliensis (BenHaM, 8), where, however, it only extends from segment xvi. to xxv. In Megascolex coeruleus there are a series of glands appended to the intestine and lying beyond the pouches; these are the ‘kidney-shaped glands’ of my description of that Annelid; they were also found by BourNE in his specimens; the actual number of pairs of these glands appears to vary as both Bourne and I give different numbers. Their structure is quite simple; they have the appearance of being formed by a much folded membrane; it is a matter of some interest from a classificatory point of view that entirely similar glands occur in the genus Typhoeus belonging to the family Cryptodrilidae. Otherwise they are unknown in the Oligochaeta. The number of pairs is less in Typhoeus. Highly characteristic of the genus Perichaeta, but also, strange to say, found in the apparently remotely allied Urobenus, are a pair of caeca of the large intestine; these occur nearly, if not absolutely, always in the twenty-sixth segment; they are directed forwards, and occupy two or three segments. A few species of Perichaeta, for example P. sieboldi, have a mass of six or seven of these caeca arising close together and appearing to be formed by the branching of one caecum. In Urobenus the caeca are in the same segment. In the remarkable Cryptodrilid Millsonia there are more than thirty pairs of caeca precisely like those of Perichaeta. VI. VascuLaR System. The Oligochaeta agree with the Polychaeta in possessing a closed vascular system, i.e. one having no communication with the body-cavity (coelom). Unlike what is found in the Polychaeta there are no Oligochaeta known which have not a vascular system, though the complication of the vessels belonging to this system THE ANATOMY. VASCULAR SYSTEM 65 varies in the different groups; they are more complex in the larger forms and on the whole less so in the smaller worms. § 1. Histology of blood-vessels. The blood-vessels of the Oligochaeta are tubular, rarely lacunar; the larger vessels, some of which are contractile, have thicker or thinner walls, and give rise in the higher Oligochaeta to an extensive system of capillaries. In the larger vessels circular as well as longitudinal muscular fibres exist and the vessels are ined by an epithelium and covered by the cells of the peritoneal investment. There is an increase in the elaboration of structure of the principal (dorsal) blood trunk, as we pass from the lower to the higher Oligochaeta. In Aeolosoma the dorsal vessel consists, according to VEsDovsky, of no more than an exceedingly fine membrane, in which no structure, muscular or other, could be detected; it is covered of course by the peritoneum. Very little more can be said of the Naids and Enchytraeidae; there is simply a delicate membrane covered with peritoneum. In Chaetogaster, however, which I reckon a Naid, it is possible to recognize faint longi- tudinal as well as transverse striae. Something similar is figured by TAUBER (8, Tab. iii, fig. 11) for Nais elinguis, and Vespovsky figures (24, Tab. iv, figs. 20, 21) and describes contractile cells (besides the peritoneal cells, with which they must not be confused) as constituting the walls of the dorsal vessel of Stylaria lucustris. One is inclined to suppose that the dorsal vessel of Aeolosoma, since it is contractile, will prove to possess muscular fibres. In the forms that have been hitherto considered there seems to be no definite lining of epithelium to the dorsal vessel. In the higher Oligochaeta, on the other hand, the epithelia] lining consists often of very large and conspicuous cells. In Phreoryctes, for example, I have figured (18) a transverse and longitudinal section through one of the perioesophageal vessels (which have the same structure as the dorsal vessel) which show (Figs. 8, 9 of plate) the cubical cells lining the lumen of the vessel ; the strong circular and longitudinal muscular layers of the vessel are also shown. VeEsDovsKy's figures (24, Taf. xiv, figs. 10-13) show the lining epithelium and at any rate a circular layer of muscles in Criodrilus lacuwm; while PERRIER has recorded a similar structure for Urochaeta. Naturally the circular! layer is much more important than the longitudinal, and it has therefore been often the only one figured. The blood itself is usually red; yellower in Naids, and colourless in Aeolosoma?. The colour, as was first shown by LANKESTER, is due to haemoglobin. ! Both circular and longitudinal fibres are described in the text (p. 118). 2 Lankester says that it is pink in Ae. quaternarium. K 66 OLIGOCHAETA The blood contains minute corpuscles suspended in it which are little more than the nuclei of the lining cells. The blood-vessels of the Oligochaeta are often provided with valves. These, however, are limited to the dorsal vessel and to the hearts. They do not appear to occur in the lower Oligochaeta—unless indeed the cardiac body of the Enchy- traeidae is derived from a fused series of valves such as occurs in Vertebrates— with the exception of Phreoryctes, where they have been described by Leypie (6) and by Timm in the dorsal vessel. In earthworms they are very general, probably universal. I have myself found them wherever I have looked for them. In the dorsal vessel they occur just where the vessel traverses the septa; in the hearts they may occur all along (cf. e.g. Perrier, 5, Pl. XV, fig. 29) from its point of origin from the dorsal vessel up to the opening into the ventral vessel. The valves are essentially proliferations of the lining membrane of the blood- vessels, the cells forming them being large and granular. The blood gland of Phreodrilus may very possibly be regarded as homologous with a fused series of valves, unless the interpretation which I have suggested in describing it be accepted in preference. $2. Main trunks. The principal longitudinal trunks in the Oligochaeta are five, all of which do not exist in the lower forms; they will be now considered seriatim. The Dorsal vessel.— This, the principal of the longitudinal trunks, is present in all Oligochaeta and is invariably contractile ; - it is not, however, always equally well developed; for in some forms (e.g. Aeolosoma) it is deficient posteriorly while in others (e.g. Chaetogaster cristallinus, Rhinodrilus ecuadoriensis, qq. v.) it terminates a little way before the anterior end of the body. In nearly all those forms where the dorsal vessel is fully developed, which include the great majority, it passes from one end of the body to the other upon the dorsal surface of the alimentary canal; in Branchiura, however, and in Dero this is only true of the anterior section of the tube; posteriorly it comes to lie on the ventral surface of the body, near to the ventral vessel. The dorsal vessel is commonly separated by a little distance from the actual walls of the canal, but along the intestine it closely invests the gut; it is not, however, in the higher Oligochaeta, covered by the intestinal peritoneum, but has a layer of peritoneal cells to itself. The way in which the dorsal vessel terminates anteriorly varies in different Oligochaeta. As regards the higher Oligochaeta we have two elaborate memoirs THE ANATOMY. VASCULAR SYSTEM 67 dealing respectively with Pontoscolex and Megascolex by PERRIER and Bourne. The following account is deduced from these two memoirs. In Megascolew the dorsal vessel bifurcates anteriorly in the first segment of the body; each of the two branches into which it divides is the equivalent of the succeeding dorso-tegumentary vessels, and like them forms a peripheral vascular network which only communicates indirectly with the ventral vessel. In Pontoscolex (PERRIER) the dorsal vessel extends as far forward as the brain; there it bifurcates and joins the branches formed by the bifurcation of the ventral vessel, thus forming ‘a vascular collar in front of the nervous collar. In these genera, in Lumbricus, and in fact in all the higher Oligochaeta the dorsal vessel gets to be very much less in calibre anteriorly and communicates indirectly with the ventral longitudinal trunks ; in these Oligochaeta the vascular system as a whole is, as will be pointed out, excessively complicated as compared with the lower forms; the fact therefore that in the lower forms the dorsal and ventral vessels communicate directly by vascular arches similar to those which occur in succeeding segments is not to be looked upon as a difference of importance, but merely as a result of the more highly-developed vascular system of the former. In the Tubificidae, for example, there is in the first segment of the body a vascular arch connecting the dorsal and the ventral vessels directly and quite similar to the following arches which put these vessels into communication in ensuing segments ; but these facts will be fully gone into in a subsequent section. Posteriorly the dorsal vessel appears gradually to fade away in some worms; in others, as in Megascolez, for example, it terminates abruptly just after giving off the last pair of dorso- tegumentary trunks. A-remarkable condition of the dorsal vessel was first described by myself in Megascolex coeruleus ; in this worm the anterior part of the tube is partially divided into two halves which reunite at the septa; a large number of earthworms are now known which exhibit this peculiarity. It is, moreover, not a question of systematic position ; the most diverse families show this condition; it has been found, for example, in Octochaetus multiporus, Acanthodrilus novae-zelandiae, Microchaeta rappi, Teleudrilus ragazzii, etc. Three degrees of the division of the dorsal vessel exist ; in Megascolex, for instance, the vessel is only double in the anterior part of the body ; in other types the dorsal vessel is double from end to end of the body; here again there is a difference; in Octochaetus multiporus and in Acanthodrilus annectens the vessel is completély double; there are two distinctly separate tubes running side by side on the dorsal surface of the gut; in Acanthodrilus novae-zelandiae there are two such tubes in the middle region of each segment, but at the septa the two tubes fuse. The interest attaching to these facts lies mainly in that they seem to K 2 68 OLIGOCHAETA indicate the persistence of an embryonic condition; for Vespovsky showed that in Criodrilus the dorsal vessel was developed from two independent tubes, and he Fig. 16. BOTHRIONEURON VASCULAR SYSTEM. (After Stole.) I-IX. Segments. 1-6. Lateral hearts. 7. Ventral vessel. 8. Pha- rynx. 9-14. Vessels supplying in- testinal network. 15. Sub-intestinal vessel. 16-19. Vessels supplying in- testinal network. 18, 21. Intestinal hearts, 22, Supra intestinal vessel. 23. Dorsal vessel. has recently extended this discovery to species of Lum- bricus (s.1.). As a general rule the dorsal vessel of the Oligochaeta is of much the same diameter throughout ; but in a few forms it is locally dilated; this is the case, for instance, with Microchueta where there is heart-like swelling in the ninth segment. In various Enchytraeids too there is a dilatation of the dorsal vessel just where it arises from the peri-intestinal sinus. The Supra-intestinal vessel—In addition to the dorsal vessel a good many Oligochaeta possess another vessel, also running along the dorsal side of the gut, which has been termed the ‘Supra-intestinal’ vessel. It is not long since the presence or absence of this vessel would have been held to be at least partly distinctive of the two groups instituted by CLAPAREDE, the ‘ Limicolae’ and the ‘ Terricolae.’ Until the researches of Stoic the supra-intestinal vessel was considered to be confined to the Terricolae, although not occurring in all the genera of that group. It is, however, now known to exist in a number of Tubificidae as. well as in the aberrant genus Phreodrilus. The supra-intestinal trunk is limited to the oesophageal region, where it takes the part with reference to the intestinal circulation that is elsewhere played by the dorsal vessel. In the oesophageal part of the alimentary canal the dorsal vessel comes to be some way removed from the gut, and it gives rise to a series of stout lateral branches which embrace the gut and join the ventral vessel without being connected in any way with the walls of the gut. It has been stated that the supra-intestinal trunk passes back along the intestine as the typhlosolar trunk; but this appears to be very doubtful; the careful re- searches of Bours (4) into the circulation of Megascolex coeruleus do not support the existence of such a vessel ; and, considering its relations to the gut and to the body-wall in the oesophageal segments, it does not seem likely on @ priori grounds that it does exist in the intestinal region, where indeed it would seem to be de trop. THE ANATOMY. VASCULAR SYSTEM 69 This blood-vessel resembles the dorsal vessel in being also directly connected with the ventral vessel; among the Tubificidae such connexions occur, and in Branchiwra there is a pair of hearts of this description coexisting in the same segment with a pair of hearts arising from the dorsal vessel; in the earthworms it is frequently the case, as I mention more in detail further on, that the same pair of hearts arise both from the supra-intestinal and the dorsal vessel. Another point in which this vessel resembles the dorsal is that it is occasionally double; in Megascolex coeruleus this is the case, as has been described by both Bourne and myself. The supra-intestinal vessel is by no means present in all of the higher Oligochaeta ; it is present in most of the genera belonging to the two families Megascolicidae and Eudrilidae. It may perhaps be a question to which of the two dorsally-placed trunks the single vessel of, for example, the Naidomorpha corresponds. I have suggested that the intimate relations of the supra-intestinal to the alimentary canal indicate that the posterior part of the dorsal vessel is its homologue and that the anterior part of the dorsal vessel is a new structure in the higher Oligochaeta—the relations between the two being somewhat analogous to those which subsist between the vena cava posterior and the posterior cardinals in the Vertebrata. This view seems to be supported by the relations obtaining in the genus Phreodrilus. In that worm there are in the anterior region of the body two trunks upon the dorsal side of the alimentary tract which I homologize respectively with the dorsal and supra-intestinal of other Oligochaeta. These two vessels can be distinguished, not only by their position but also by their minute structure; the vessel which is closest to the wall of the gut, lying in fact upon it, has thin walls and is full of blood after death; the other has thicker walls and is not so full of blood after death; moreover the latter has not the coating of chloragogen cells which occur in the former; it is coated with flattened cells without pigment; this vessel, which I believe is the dorsal vessel of the higher Oligochaeta, terminates at about the fifteenth segment; behind this point there is only the supra-intestinal. The question, therefore, arises whether the vessel, which I have termed dorsal, is really the equivalent of the similarly named vessel in the Naids, etc. The Ventral vessel.—This vessel is present along the whole body in all Oligochaeta. It is invariably a single tube never showing any signs of duplication as does the dorsal vessel. The ventral vessel also differs from the dorsal vessel in that it is never contractile, Another fact of importance is that it is the first blood-vessel to be developed; this is at any rate the case with Rhynchelmis and Lumbricus (several species) in which alone the origin of the vessel has been carefully studied. The ventral 1 Phreoryctes is said to be an exception to the statement. 70 OLIGOCHAETA vessel in its earliest stage is simply a slight thickening of the splanchnopleure; for some time it remains solid and only subsequently becomes hollow. In the view of some writers, for example WILSON, the ventral vessel is from the first hollow and its cavity is the remains of the segmentation cavity. In many of the lower Oligochaeta the ventral vessel terminates, in front by bifureating and ultimately joining the dorsal vessel by a loop round the gullet; in Chuetogaster however it ends in a solid cellular cord which bends upward and ends freely in the neighbourhood of the cerebral ganglia. In the higher Oligochaeta the ventral vessel branches anteriorly and communicates with the dorsal vessel only through a capillary system. In two Tubificidae the ventral vessel terminates anteriorly in an altogether peculiar fashion. In Lophochaeta the ventral vessel appears to end in the eighth segment in a pair of hearts which communicate with the supra-intestinal trunk ; but from the angle formed by the bifurcation an extremely slender vessel passes forward and after receiving three branches from the sub-intestinal vessel joins that vessel in the seventh segment; the single vessel formed by the fusion of the two terminates anteriorly in the usual way. In Bothrioneuron the narrow continuation of the ventral vessel commences in segment vii., and without receiving any branches from the sub-intestinal joins it in segment vi. These facts were described and figured by Stouc (8), whose figures are here reproduced (woodcuts, figs. 16, 18). The Sub-intestinal vessel.—I apply this term to the usually paired vessels called by Perrier and Bourne ‘ Intestino-tegumentary’ vessels, and by BENHAM ‘lateral longitudinal’ vessels. They are first seen in the family Tubificidae; in Lophochaeta and in Bothrioneuron where their relation to the ventral vessel has already been referred to. In Lophochaeta the ventral vessel divides in the seventh segment into two trunks, one lying above the other; the uppermost of the two is closely applied to the ventral wall of the alimentary canal and appears to be intimately concerned with its blood supply; it has much the same relations to it below that the supra-intestinal vessel has above; the same vessel occurs in Bothrionewron, but it begins earlier, in the sixth segment. In the higher Oligochaeta this vessel, or at any rate the vessel which I regard as its equivalent, is invariably double—with the possible exception of the Lumbricidae; Howes in his ‘Biological Atlas’ has figured in that worm a single sub-intestinal vessel which Jackson (‘Forms of Animal Life’) considers to be non-existent, but to have been mistaken for the impression of the attachment of the mesentery. In many other earthworms there are a pair of these vessels which arise from the intestinal plexus‘ and run for a short distance closely attached to the 1 In Benhamia schlegelii Horst figures and describes these vessels as originating from the dorsal trunk just in front of the antepenultimate pair of hearts. THE ANATOMY. VASCULAR SYSTEM 71 ventral surface of the gut; later however they leave the walls of the intestine and run freely suspended in the body cavity; they end anteriorly in a network of capillaries. These vessels occur in Megascolea (Bourne), Pontoscoler (PERRIER) (woodcuts, figs. 20, 21), Hudrilus (BeDDARD), and other forms. In Eudrilus the sub-intestinal vessel is partly double and partly single like the dorsal vessel of other earthworms; it bifurcates in the neighbourhood of the calciferous pouches and is single between them. In another Eudrilid, Libyodrilus, I have traced the course of these vessels for a little distance ; they are double all the way and give off two pairs of branches in each of the segments through which I followed them; one pair of branches go to the ‘septum, the other to a muscle suspending the intestine ; numerous minute twigs connect them with the intestinal plexus. In Megascolex coeruleus the vessel in question only extends back to the thirteenth segment; after this there is a small vessel in each segment running from intestine to septum which is its equivalent. The Sub-nervian vessel. This is absent in the lower Oligochaeta and is by no means always present in the earthworms. It exists in Lumbricus, Perichaeta, and some other genera, and lies, as its name implies, beneath the nerve cord; it is even sometimes partially imbedded in the ventral body-wall. The presence or absence of this vessel served CLAPAREDE with one of his characters for separating the Limicolae from the Terricolae. § 3. Commissural vessels. The dorsal vessel in all Oligochaeta is connected with the ventral vessel by circular trunks which run round the alimentary canal. The simplest and most primitive arrangement of the vessels appears to be that which characterises the families Tubificidae, Phreoryctidae, and Lumbriculidae. In these worms there are at least one pair Fig. 17. 3 <= oF IN > Xill XIV xv \ 4 Jo4\n XVI E XVII] > Mill | SPARGANOPHILUS. GENERAL ANATOMY. (After Benham.) i, 4, 6. Perivisceral vessels, Dorsal vessel. 5. Spermatheca. 8. Sperm-sacs. 9. Intestino-tegumen- tary vessels. 10, Ovary. 11, 12. Dorso- and ventro-tegumentary trunks. 2, 3,7- of such vessels in each segment of the body—the regular metamerism of the vascular system being thus very apparent. In the anterior region of the body one or more of the commissural vessels are specialized and become contractile, being then usually termed 72 OLIGOCHAETA ‘hearts’ In Tubifea rivulorwm, for example, the commissural vessels of segment viii are greatly dilated and contractile. In Limnodrilus and Clitelli there are two such contractile circles, but they are not always larger than the unmodified perivisceral trunks. In other Tubificids a larger number of the anterior periviscerals are modified into contractile hearts. Further details will be found under description of Tubificidae. In the Naidomorpha the direct connexions of the dorsal and ventral vessels only exist in a few of the anterior segments; this also is the case with the Enchytraeidae and the Aphaneura. The smallest number of commissural Fig. 18. vessels occurs in Pristina equiseta, where BouRNE only found one. The fact that in the newly-formed bud of Uncinais littoralis there are commissural vessels in all the segments, most of which become afterwards lost, is an indication that the disappearance of all but the few anterior commissural vessels in the Naidomorpha and Enchytraeidae is due rather to degeneration than to the retention of any primitive character. In some Tubificids there is another class of commissural vessel in the anterior segments of the body ; one or more of the hearts instead of forming the dorsal and the ventral vessels unite the supra-intestinal with the ventral. The name ‘intestinal hearts, introduced by Perrier for the corresponding structures in earthworms, may be applied to these. It is difficult to determine whether or not these tranks are serially homologous with the LOPHOCHAETA. VASCULAR Yemaining hearts and with the peri-intestinal vessels of SYSTEM OF SOME OF THE the segments in the posterior region of the body. ANTERIOR SEGMENTS. In Bothrioneuron, Lophochaeta, and Phreodrilus, the (After Stole.) ; : i . i intestinal hearts occur in segments posterior to those which 1. Ventral vessel. 2-6. Vessels @ ‘ ‘ : joining intestinal network, 7, Slen. CODtain the dorsal hearts; but in Branchiwra the eighth der posterior part of ventral vessel segment contains two perivisceral vessels, of which one just after it joins. 12. Sub-intestinal : vessel. 9, 13, Intestinal hearts. 15, seems to be the equivalent of the intestinal, the other of 16. Commissural vessels. 17. Dorsal seawal. the dorsal heart. In the higher Oligochaeta the intestinal hearts are connected in many cases with both of the dorsally running blood-vessels; so that one connection may be regarded as secondary. In these Oligochaeta, in the earthworms in fact, the commissural vessels are confined to the anterior segments of the body; but this specialization is not due, as it may be in the Naidomorpha, to degeneration ; THE ANATOMY. VASCULAR SYSTEM 73 it appears to be due to the fact that the commissural vessels of the posterior segments have given rise to the integumental blood-plexus, and have become largely lost in the process; there are, as I shall point out later, the beginnings of this plexus to be seen in the Tubificidae; it attains to its highest development in the Oligochaeta terricola ; but in the embryo Lwmbricus, as VEIDOVsKY has shown (see woodcut, fig. 19), each segment has a pair of commissural vessels. The number and position of the hearts in the earthworms varies very considerably; it is rare, however, to find them extending behind the thirteenth segment. As a rule the last three or four, often two of these, are connected either with both the dorsal and supra-intestinal vessels or with the latter alone; this kind of connexion, however, does not occur in the Lumbricidae, and apparently not in the Geoscolicidae; it occurs only in the Megascolicidae and the Eudrilidae among the Megadrili; the Moniligastridae agree in this character with the Geoscolicidae and the Lumbricidae. As a rule the intestinal hearts are much more dilated than the others, and they show in a more pronounced fashion the moniliform character which these organs often exhibit; this is really due to the presence of valves along the course of the commissural vessels, which allow the blood to flow in one direction only. § 4. Peripheral circulation. In addition to the longitudinal trunks and to the commissural vessels which unite them, there is in all Oligochaeta a system of smaller vessels, which form plexuses and may be termed capillaries; it is convenient to divide these capillary networks into two series, the integumental and the intestinal. The former includes all the capillaries which ramify in the thickness of the body-wall, the septa, and in fact all the organs of the body except the alimentary system; the reasonableness of making this apparently artificial division is shown by the fact that in the lowest Oligochaeta there is no capillary system except that which supplies the intestinal walls, and that the two systems are quite distinct, being only indirectly connected in the higher forms. In the Aphaneura, the Enchytraeidae, and the Naidomorpha, the intestinal system of capillaries is the only one that is present. In the two former groups the dorsal vessel loses itself in this plexus; it seems a little doubtful whether in the adults of any of these worms there really exists, as has been described, a blood-holding space surrounding the gut; when the capillaries are gorged with blood, there would naturally be a tendency to the obliteration of the boundaries of the meshes of the network which would of course produce the impression of a continuous sinus. As to Aeolosoma, however, the figures of Vespovsky show plainly that there is a plexus and not a sinus; in the Enchytraeidae L 74 OLIGOCHAETA a sinus has been generally asserted to exist; but MicHArELsen figures in Stercutus, for example, appearances which are much more in accord with the assumption that there is really a network: he speaks, however, in this case of a ‘Darmblutsinus.’ The same word is used in his revision of the family, and therefore containing his latest opinions on the matter, with which also VespDovsKy agrees. The existence of this sinus, if real, is of interest in connexion with the perienteric sinus in certain Chaetopods (for example Fabricia) ; the fact that in Aeolosoma and the Enchytraeidae the dorsal vessel arises from this sinus becomes additionally interesting from SALENSKY’s discovery that in Terebella, ete., the embryo has a dorsal vessel similarly connected with, indeed arising from, a perienteric blood-sinus. As to the Oligochaeta, embryology does not seem to indicate that this sinus is primitive; in Rhynchelmis VEIDOVSKY describes the dorsal vessel as arising from the perienteric plewus (not sinus). It will be noted, however, that the limited extent of the dorsal vessel and its origin out of the perienteric vessels is an embryonic character in the Aphaneura and Enchytraeidae. Whatever may be the case with the lowest Oligochaeta, it is certain that in the Naidomorpha and in all the groups above them, there is not a plexus but a network of capillaries in the intestinal walls; this has been figured by Store and others in the Naidomorpha, and by the same and also by others in the Tubificidae; in these worms the network is fed from the dorsal vessel, and the blood returns into the ventral vessel; the network at any rate has connections with both vessels, Among earthworms Sparganophilus has been said to possess a sinus by BenHam; I confess to being unwilling to accept this statement, for the reasons already stated, i.e. the difficulty of proving that the supposed sinus is not really a plexus with largely obliterated boundaries. The intestinal network of the higher Oligochaeta is described below in the genus Megascolex, in which it has been carefully studied by Bourne. The integumental blood plexus shows a gradual increase in complexity as we pass from the higher to the lower forms. It is, as already stated, entirely absent in the Enchytraeidae and the Aphaneura. The first traces are to be found in Limnodrilus, where the lateral commissural vessels give off (in Limnodrilus hoff- meisteri at any rate) a bunch of small vessels which seem to end caecally in the skin. In other Tubificidae the integumental system is much more developed; in Ilyodrilus, for example, where the circulation has been carefully studied by Sroto, there is a complex network in the integument; it appears from his figures (the text being in the Bohemian language is inaccessible to me) that in each segment of the body behind the first a special pair of vessels is given off from the dorsal vessel which supply the plexus, and that branches of the commissural vessels receive the blood from THE ANATOMY. VASCULAR SYSTEM 75 the plexus and convey it to the ventral vessel. The integrity of the commissural vessels is, however, preserved ; in the higher Oligochacta the integrity of these vessels is lost (except in the embryo, see woodcut); they become largely dissolved into the network of capillaries. In the lower Oligochaeta it is only the actual body-wall which sometimes possesses a capillary network, none of the other organs of the body (as a general rule) ’ have such; the sperm-sacs, for instance, are fed by specially elongated perienteric loops belonging to the segments in which they occur. The nephridia in Rhynchelmis are peculiar among the lower Oligochaeta, in that they have similar loops attached to them and following their windings; and in Tubifex Nass has described vessels in the nerve-cord. With these exceptions there is no peripheral vascular system other than the integumental network until we reach the true earthworms ; and here it is not always at the same pitch of development ; in the smaller forms, such as Ocnerodrilus the nephridia seem to be quite unprovided with vascular networks. Epidermal capillaries—It has been known for a long time that in the clitellar region the terminal branches of the vascular system push their way in among the cells, forming loops, which, however, stop short some little way below the surface. These capillaries are figured by CLAPAREDE and by others. As to the vascularity of the rest of the epidermis, it was, I believe, first pointed out by myself that this was the case with Megascolex coeruleus (2) and some species of Perichaeta (8). The extension of blood-capillaries into the epidermis of Crio- drilus has been figured by Rosa (12), and quite recently it, has been discovered by LenHossEK (1) that the epidermis ; ae : 1. Aperture of ‘head kidney.’ 2. of Lwmbricus—not only the clitellum—is also vascular. Brain. 3, Septal glands. 4,5. Dorsal Even among the more delicate aquatic species this con- ee a. ae dition, very likely universal in the earthworms, is not unknown. Limnodrilus is furnished with apparently caecal vessels, which terminate between the epidermic cells. It has been stated by the SaRasins that in Perichaecta the capillaries actually reach the exterior, and open there; but this appears on the face of it to be unlikely, and at any rate needs further proof. The statement was made incidentally in connexion with an alleged similar opening of blood-capillaries on to L2 EMBRYO LUMBRICUS. (After Vejdovsky.) 76 OLIGOCHAETA the exterior in the Gymnophionae. The physiological meaning of ‘intra-epithelial blood- capillaries, as LanKEsTER has termed these structures in the leech, where he was the first to discover their existence, seems to be clear. One of the characteristics of the Oligochaeta is the rare occurrence of branchiae; Dero, Chaetobranchus, Branchiura, Hesperodrilus branchiatus and the questionable Alma are the only real (or reputed) Oligochaeta which form branchiae. The absence of these special organs is compensated for by the utilization of the entire skin as a branchial organ. ‘The efficiency of the skin as a branchial organ must be largely increased by the penetration of the capillaries into the outermost layers. Bourne was led by his researches into the vascular system of Megascolex coeruleus to a reasonable view of the course of the blood in that species which will probably, as he thinks, prove to be more widely characteristic. Excepting at the head end of the body, where the vascular system like other organs shows a cephalization, it is metamerically arranged. Moreover the fact that an earthworm. can live after a considerable part of its body has been shorn away indicates that each segment is to some extent independent in its circulatory mechanism. There is no doubt—all observers agree upon Geis. aaa that point, which can be easily seen in the living ee worm —that the blood flows forwards in the (iiter Panvten) dorsal vessel. In the cephalized region of the v.d. Dorsal vessel, te Ventral. vi Sub- body the blood passes down into the hearts; eis amt — ai these contract from above downwards, just as the dorsal vessel contracts from behind forwards. In the intestinal region of the worm there are two sets of vessels connected with the dorsal vessel—the dorso-integumentary and the dorso-intestinal. It appears that blood flows from the latter into the dorsal vessel, and out of the dorsal vessel into the former. This view is not that universally accepted. In the anterior region of the body of course, the supra-intestinal vessel is supplied from the same source as is the dorsal vessel posteriorly. The ventral vessel of Megascolex communicates with the dorsal vessel anteriorly and directly by the hearts; posteriorly it communicates with the same tube, indirectly by the ventro-tegumentary vessels. According to BourNE blood reaches the ventral vessel by the hearts; of the truth of this there can be hardly any doubt; he considers, however, that the ventro-integumentary vessels take THE ANATOMY, blood away from the ventral vessel to the parietes. There are thus two sets of vessels which convey blood to the integument—the dorso-integumentary and the ventro-integumentary. From the integument a series of intestino-integumentary vessels again returns the blood to the intestinal network, whence, as before stated, it reaches the dorsal vessel. VII. BLoop-Guanps. Connected with the vascular system there are in several Oligochaeta structures which seem to be of a glandular nature. Such structures occur in the En- chytraeidae, the Lumbriculidae, the genus Phreodrilus, the Perichaetidae, and perhaps the Eudrilidae. It will be convenient to commence with a descrip- tion of these various organs in the groups mentioned, before discussing the morphology and the functions which they may perform. In the Enchytraeidae the dorsal vessel sometimes contains a cellular rod which has been named the ‘Herzkérper’ by MIcHAELsen (woodcut, fig. 22). It was described first (MicHAELSEN), where it consists of a solid rod of cells attached to the ventral side of the dorsal blood- vessel, and extending along its whole length; ‘in M. mirabilis and M. primaevus it is thick with irregular, often strong swellings multicellular in section. In M. falciformis, M. bewmeri, and M. flavidus, it is thinner, quite smooth, with only feeble swellings, and in the genus Mesenchytraeus in section shows only a few cells.’ The organ is figured by MicuaEtsen. In a later paper the same organ was described in Stercutus. It has been justly compared by him to the cardiac body of certain Polychaetes, such as Pectinaria belgica, and a few others. As to its function it was suggested by MIcHAELSEN that it served to ease the contractions of the dorsal vessel ; he pointed BLOOD-GLANDS 77 PONTOSCOLEX. CHIEF TRUNKS OF VASCULAR SYSTEM. (After Perrier.) v.d.,v.m. Dorsal vessel. .l. Con- tractile heart. c. i. Intestinal heart. v. i Supra-intestinal vessel. v.1l. Lateral vessel, v.s. Ventral vessel. v.t. Peri-intes- tinal vessel. ¢.7., 7. ¢. Smaller branches of ventral vessel. 78 OLIGOCHAETA out that the flow of the blood forwards would be facilitated if the tube were completely closed posteriorly during contraction; the presence of this cardiac body would help to fill up the tube, and allow the lumen to be entirely obliterated without reaching the maximum degree of contractility of the dorsal Fig. 22. blood-vessel. The genus Lwmbriculus and other Lumbriculidae have a series of caecal diverticula (woodcut, fig. 23) of the dorsal vessel, which are clothed with large chloragogen cells, and are contractile; these were formerly mistaken for caeca of the gut itself, but there is no doubt that this was an error ; they serve as temporary reservoirs of the blood, which is HEART BODY OF ENCHY- TRAEID. (After Michaelsen.) presumably subjected during its sojourn in them to the action of the peritoneal cells which envelop them. Nothing of the kind exists in any worm that is not a Lumbriculid, though they are not found in the Lumbriculid genus Stylodrilus. A third kind of blood glands (woodcut, fig. 24) are to be met with in various species of the genus Perichaeta. They were originally described by Perrier (8), who thought them to be of the nature of salivary glands; they occur in Perichaeta houlleti, for example, at the sides of the oesophagus and show a distinctly metameric arrangement, being grouped in accordance with the segments. These glands consist of a number of spherical acini, which have a solid appearance, and are composed of small rounded cells ; they have, however, as I (48) showed, no connexion whatever with the gut, and are simply dilatations upon the blood-vessels comparable to those dilatations which occur along the course of the nephridial tubes, than which, however, they are considerably larger; a blood-vessel can be traced into them and out of them. They are covered externally by masses of pigment-holding peritoneal cells, LUMBRICULUS : BLOOD GLANDS. (After Claparéde.) and form with these fairly compact glandular masses. Something of the same kind appears to exist in at any rate one species of Acanthodrilus, A. rosue. 1. Ventral blood-vessel. 2, Dorsal blood-vessel. 3-5. Branches of last In the aquatic Oligochaet genus Phreodrilus another with caecal twigs. s . Be i 7" variety of organ of possibly a similar physiological nature occurs; in the twelfth and thirteenth segments of this worm is a coiled tube which puts the dorsal and the ventral vessel into communication; it is so much coiled that I have not been able to ascertain its exact shape; the interior of this vessel, which THE ANATOMY. BLOOD-GLANDS 79 is perhaps the homologue of the perienteric vessel of its segment, is largely filled by a mass of big vesicular cells containing granules. They are so numerous as to nearly occlude the lumen of the blood-vessel. The last variety of these organs are possibly the modified calciferous glands of certain genera of Eudrilidae, for instance Stuhlmannia. I have, however, described these in full under the description of the calciferous glands, and need not recur to the matter here. The nature of these various glands now requires consideration. There can, I think, be no morphological comparison between the organs in Perichaeta and those of the Lumbriculidae, on the one hand, with the other varieties of blood-glands; nor is there any relation except perhaps a physio- Fig. 24. logical one between the blood-glands of the two genera of worms mentioned; the other organs do appear to me to be probably mor- phologically connected. There is no doubt, I imagine, that the peculiar glands of certain Eudrilidae which I have described above are really the equivalents of the calciferous glands; their lumen, although much reduced, PERICHAETA : BLOOD GLANDS. communicates with that of the oesophagus; _ «. Dilatation upon blood-vessel filled with corpuscles. and the segments which they occupy are those ~ caer ae oe in which calciferous glands, when present, commonly lie. At the same time it appears to be at least probable that their function is a different one from that possessed by the calciferous glands ; I could find no evidence of a secretion of calcareous particles ; this merely negative evidence is not perhaps very strong, since I have often failed to discover any such particles in the lumina of glands which are undoubtedly calciferous glands. It is the structure which leads to the inference that the glands now under consideration are not functionally calciferous glands; this is most clearly marked in Eudriloides, and the structure in that genus offers a clue to what is the real function of the glands in question. The peculiar cells which make up the mass of the glands become altered in Hudriloides towards the periphery of the glands; it gets to have a distinctly columnar arrangement; but the columns of cells are disposed round a lumen which is filled with blood and which is a blood-vessel traceable into connexion with the other blood-vessels of the gland and the surrounding organs; the structure seems to be irreconcileable with any other theory than that the glands in question have some secreting function in relation to the blood or eliminate effete matters from the blood; we have in fact a gland originally performing a function connected 80 OLIGOCHAETA with alimentation converted into a quite different physiological path, and one which must bear some relation to the vascular system. Now there is some evidence that the ‘cardiac body’ of certain Enchytraecidae has had asimilar origin. In Buchholziu the paired dorsal diverticula of the oesophagus, which are comparable probably to the calciferous glands of earthworms, are surrounded by a blood-sinus where they are attached to the gut; this blood-sinus becomes further forward the dorsal vessel; there is thus a diverticulum of the oesophagus, as it were thrust into the dorsal vessel; it is to be pointed out in the first place that a dorsal diverticulum of the gut never coincides a . . BECRECHZ EE: CARCINEEOUS Sle with a cardiac body; Horst was apparently (After Michaelsen.) 1. Peritoneal layer. 2,3. Tubules of gland 4. the first who compared the cardiac body Dorsal vessel. 5. Lumen of intestine. 6. Ventral of the Chlorhaemidae with the gut diverti- vessel, 7. Peritoneum. 8,9. Muscular and epi- thelial layers of intestine. 12. Vascular sinus of ions my opinion a valid objection to this identi- culum of the Enchytraeidae; it is not in fication to point out, as CunNnINGHAM has done’, the absence of any present connexion between the cardiac body and the epithelium of the oesophagus ; such a communication may easily have become lost; there are plenty of analogous instances. If we imagine the gut-diverticulum to lose its lumen a cardiac body is at once produced. We should therefore look upon those forms which have a cardiac body a3 being more modified than those in which there is a gut-diverticulum; as in the genus deolosoma there is a trace at least of a cardiac body, better marked in the perhaps allied’ Ctenodrilus ; these genera are perhaps to be regarded as the descendants of genera in which there was a dorsal diverticulum of the oesophagus—an argument for the non-primitive character of Aeolosoma. It seems to me to be also possible that the blood- glands of Phreodrilus are referable to the same characteristic diverticula of the oesophagus. The cells contained in the lateral vessels will be on this interpretation the remains of the calciferous glands; the vessel which contains them will be the hypertrophied vessel originally supplying these hypothetical glands; this may also help us in understanding the anomalous presence of an intestinal heart in Branchiura in the same segment as that which also contains a dorsal heart; if the. intestinal heart be regarded as the last trace of a vanished pair of calciferous glands the difficulty » «Qn some points in the Anatomy of Polychaeta,’ Q. J. Micr. Sci. vol. xxviii, p. 259, ete. THE ANATOMY. RESPIRATORY ORGANS 81 of accounting for its existence vanishes also; but this is, of course, purely speculative. There are various interesting analogies, if no more, between this series of glands in the Oligochaeta and certain structures in the Vertebrata. WELDON has traced the origin of the supra-renal body in the Marsipobranch Bdellostoma to a detached portion of the pronephros, and he has described and figured an originally secreting gland with blood in its lumina—a state of affairs closely paralleled by the condition which I have just described in Hudriloides. A closer resemblance still is offered by such glands as the thyroid and thymus; originally connected with the oesophagus, or with diverticula of the same, these glands become entirely detached from it, and have acquired some function in relation to the vascular system. It is also said that the spleen is developed as a diverticulum of the gut; if this be proved to be the case the analogy is so close that we are almost justified in an actual comparison of the blood-glands of these Oligochaeta with the vertebrate spleen. The spleen is permeated by blood-vessels just as are the glands in the Oligochaeta, and its origin as a diverticulum of the mesenteron leaves no resemblance unaccounted for. At the very least the analogy is interesting and I draw attention to the resemblances for what they may be worth. VIII. ReEsprraTORY ORGANS. Dealing as this work does with a group of worms which were termed by CuvIER ‘ Annélides sétigéres abranches, and which are constantly distinguished by the absence of branchiae from the Polychaeta the present chapter might seem to be superfluous. Nevertheless there are a few forms which spossess special respiratory organs, and two in which these branchiae are much like those of certain Polychaeta. In the great majority of Oligochaeta there are no special respiratory organs—the general body surface occupying the place of a lung or branchia*, Where the integument is thick there are always plexuses of blood capillaries in the integument, which bring” the vascular system into close relations with the external medium and presumably allow of an exchange of gases. The blood, as has been already mentioned, is in all Oligochaeta, with the exception of Aeolosoma, Chaetogaster, and certain of the Enchytraeidae, tinged with Haemoglobin; we may fairly suppose that this substance plays the same part in respiration among these Annelids as in the Vertebrata. The efficiency of the skin as an organ of respiration in many Leeches is largely increased 1 The nephridia were once regarded as respiratory organs and as the equivalents of the tracheae of insects. The dorsal pores also were considered to perform a similar function. M 82 OLIGOCHAETA by the extension of the blood capillaries to the epidermis itself; this interesting fact was first discovered by Lankestsr. I myself extended this discovery (8) to Earthworms, and in the genera Megascolex, Perichaeta, Criodrilus, Moniligaster, &c., as I and others have shown, the epidermis of the body in general—not merely the clitellum—is vascular. As a general rule the lower Oligochaeta, in which the dermo-muscular tube, in correspondence with their small size, is actually—sometimes also relatively—thinner, than in the terrestrial worms, have no development of a capillary system in the skin. This rule, however, is not without exceptions. Limnodrilus Hoffmeister has tufts of blood capillaries which arise from the peri-intestinal trunks and enter the body wall, reaching even to the epidermis itself [VEsDovsKY, 24, Taf. viii, figs. 16, 17]. More highly developed still is the integumental vascular network of Ilyodrilus (Stoic 8) and Branchiwra (BepparD 58). Many Tubificidae and Lum- briculidae, appear to respire chiefly at the posterior end of the body; they live in the mud at the bottom of ponds, ditches, &c., with the head implanted and the tail waving about in the water. Now in the worms which have this habit, and for the matter of that in others too, the body gradually diminishes in calibre and in the thickness of its walls towards the anus; hence the blood is necessarily brought into closer relation with the surrounding water. There is in these Oligochaeta, at least, a commencing localization of the respiratory function to the tail end, in accordance with the attenuation of the body in this region. And we find that when branchiae are developed they are in every instance but one confined to the caudal extremity. For a long time the only Oligochaet known, which could be said to possess special respiratory organs was Dero. This genus of Naidae is remarkable for possessing at the end of the body an expanded hood formed by the widening out of the anus; from the inner surface of this arise two pairs of (usually) cylindrical processes. These processes, as well as the hood which covers them, are ciliated; they can only be moved by means of intrinsic muscular fibres. The principal descriptions and illustrations of this branchial area are those by Perrier (10), and BousrizLp (8). In describing the organ I shall follow PrRrier’s description and illustrations of Dero ‘ obtusa’ (=really D. perrieri, Bousf.). The branchial processes themselves are covered with a ciliated epithelium and their cavities are largely occupied by spindle- shaped or stellate muscular fibres’. The vascular supply is derived from a direct continuation of the dorsal and ventral vessels. The ventral vessel passes undivided to about the middle of the hood; here it divides into two trunks which run round the margin of the hood and give off six branches—one to each of the branchial * In D. digitata there are also retractor muscles for each branchia, THE ANATOMY. RESPIRATORY ORGANS 83 processes, and one on each side passing obliquely across the hood; they then bend upwards and become continuous with the dorsal vessel; each branchial capillary runs up the branchia to its tip and then bending upon itself runs down the opposite side of the branchiae; these and the other branches fuse together and form the dorsal blood-vessel. In Dero obtusa the circulation in the branchiae is somewhat simpler; it was described and figured by p’UpEKEM (1). The ventral vessel divides as in D. perrieri but simply pursues a sinuous course, passing up and down each branchia; the right and left halves of the circle unite at the base of the branchial hood to form the dorsal vessel. Dero digitata has more complicated vascular loops than even D. perriert. The arrangement of these has been worked out by Stoic (2). Each of the four branchial processes has two capillary loops instead of only one; and there are two circular vessels, derived from the ventral vessel, which form complete circles and do not communicate with the dorsal vessel except by the recurrent loops from the branchiae. It seems clear from the habits of the worm and from the structure of these circumanal processes that they must be regarded as branchiae; the expanded hood which is itself in some species furnished with elongated processes is no doubt also branchial in function. The next Oligochaet, in order of discovery, which is branchiate, is Alma nilotica. In the systematic part of this work I discuss whether this form (recently re-described by LEvINSEN as Digitibranchus niloticus) be really an Oligochaet. The conclusion arrived at is that it is an Oligochaet. The branchiae, like those of Dero, are found at the posterior end of the body. It is very desirable that this form should be re-investigated, for at present there are no details concerning the structure of the supposed branchiae to hand. There is, however, hardly room for doubt as to the branchial nature of the short cylindrical processes which are found upon the last sixty or seventy segments of the body. They occur just to the dorsal side of each dorsal pair of setae and there are four or five on each side, sometimes simple and sometimes branched. Chaetobranchus sempert is a remarkable branchiate Naid, apparently known to Semper, and lately described by Bourne (1). I can confirm from personal observations Bourne’s description of the branchial organs, which, unlike those of Dero, are confined to the anterior part of the body. The most anterior, after the first one or two pairs, are the longest; and in those anterior ones are imbedded the long capilliform setae of the worm; further back the setae are independent of the branchial processes. The inclusion of the setae within them is not unsuggestive of a comparison with parapodia of the Polychaeta. These branchia in Chaetobranchus are ciliated externally, they contain a capillary loop M2 84 OLIGOCHAETA which runs in the axial cavity of the branchiae; the walls are cellular and have no muscular fibres. In Branchiwra the branchiae are not lateral in position as in the last genus, but dorsal and ventral. They contain a prolongation of the coelom, which, however, is shut off by a diaphragm from the general coelomic cavity. The branchiae are contractile owing to the presence of a layer of muscular fibres lying immediately beneath the epidermis; the latter is not ciliated. Immediately beneath the epidermis is a blood-vessel on either side. The branchiae are limited to the posterior region of the body. The reason for this is probably that this Tubificid, like others, rests with its head imbedded in the mud and its tail waving freely in the water. The last branchiate Oligochaet is also a Tubificid, Hesperodrilus branchiatus, in which the branchiae are like those of Branchiura, but lateral instead of dorsal and ventral. IX. REPRODUCTIVE System !. The Oligochaeta like some other animals which are hermaphrodite possess a com- plicated series of organs related to the reproductive function. We can distinguish the essential organs, and those which are unessential and only concerned with impregnation or the liberation of the genital products. The essential organs are of course the ovaries and testes—the gonads; these are the first part of the reproductive system to make their appearance in the embryo. Then there are the ducts which convey the sexual products to the exterior, the sperm-ducts and oviducts, and the sperm-sacs and egg-sacs where the sexual elements undergo development; finally we have a series of organs which are concerned, in the mutual impregnation of the worms; the glands and sometimes penial setae appended to the sperm-ducts, the spermathecae for the reception of the sperm during copulation, etc. The various organs essential and non-essential have fixed positions in the body of the worm; one organ is found always in one segment, another in a second segment, in every species, the positions being characteristic for the species or the genus or family as the case may be. The table appended illustrates the varying position of the parts of the reproductive system in all the families of aquatic Oligochaeta and a few earthworms. The reproductive organs are segmentally arranged just as are most of the other organs of the body; but, as also is the case with other organs, the metameric arrangement is sometimes lost or obscured; the sperm-ducts for instance are not always confined to a segment nor are they framed of a series of metamerically ' For asexual reproduction, see under Acolosoma and Naids. THE ANATOMY. REPRODUCTIVE SYSTEM 85 arranged parts. The sperm-sacs, too, though often ranged with an absolute regularity, sometimes show the same kind of divergence from what we must consider to be the normal for a segmented worm. Plates I and II represent the genitalia of various Oligochaeta depicted diagram- matically. SPERMATHECA, | CLITELLUM. | TESTES | OVARIES. | $ PORE. |OVIDUCAL PORES. Aeclosoma . . 133;38&454k&5 5-6 v vi absent 6 or 3, 4,5 Enchytraeidae . 5 II-13 xi xii 12 13 or in Buchholzia i 5 8,9 vii viii a) 29 Naidomorpha 5 5-7 v vi 6 6/7 Phreodrilus : 13 12-15 x, xi xii 12 12/13 Tubificidae . . 10 10, IT x xi II Ir/i2 Trichodrilus . . II, 12 x xi Io 11/12 Claparedilla . ) . 2 Stylodrilus { 2 - a m ere Phreatothrix . . JI, 12 x xii Io 11/12 Rhynchelmis . . 8 ix, X xi Io 11/12 Lumbriculus . . TO, II, 12 ‘ 8 To, IL Eclipidrilus * 9 10 I0/II Sutroa. . . . 8 7-15 ix, x x Io I1/i2 Phreoryctes . . 7,8 10-13 x, xi xii, xiii Il, 12 12/13, 13/14 Pelodrilus. . 8 II-1g X, xi xii 12, 12 12/13 Perichaeta . : 5 (7)-8 (9) 14-16 x, xi xiii 18 14 Megascolex . .| 5 (6, 7)-8/9 13 (14)-17 x, xi xiii 18 14 Acanthodrilus . (7) 8,9 13-17 (19) x, xi xiii 18 14 § 1. Gonads. The gonads are developed from the peritoneal epithelium and are nearly always paired structures, probably they are really paired in origin in such forms as Aeolosoma where they appear to be single. Both male and female gonads are present in all Oligochaeta ; there is no instance known of an unisexual form. The ovaries are most usually a single pair but there are sometimes an additional pair; no more than two pairs of ovaries have ever been certainly made out}, The ovaries invariably agree in position with the testes, but they are of course situated in different segments ; 1 Except in abnormal specimens such as those described by Woopwarp (1, 2). 86 OLIGOCHAETA they furthermore agree so closely with the testes that in the early stages it is impossible to distinguish the two kinds of gonads save only by the segment which they happen to occupy. Not only is there this close agreement in structure (in the immature condition) and in situation, but the shape of both gonads is at first identical; the immature ovary like the immature testis is somewhat pear-shaped in outline, the broader end being attached to the septum; later on the free end of the ovary, as is also the case with the testis, may become frayed out into a number of processes. The ovaries always lie behind the testes; the only possible exception is in the genus Plutellws, where PERRIER (8) has stated that the ovaries are in front of the testes; if, however, a worm described by BenHam (8) as a Plutellus is really a member of this genus, there is nothing abnormal in the position of the female gonads. As a rule the gonads are all in consecutive segments, the ovaries following the testes, the rule indeed has very possibly no exception; this at first sight appears to be an inaccurate statement; for in Lwmbricws, and indeed in all earthworms, the ovaries are in the thirteenth segment, while the last pair of testes, if there are two pairs, is in the eleventh segment; there is thus a gap of a segment between the last testis and the ovary of its side of the body. In embryos of Lumbricus, however, as was shown , by WoopwarbD, and in embryos of Octochaetus, as has been demonstrated by myself (51), there is an additional pair of ovaries in the twelfth segment, which never comes to maturity and disappears early. There are, therefore, some grounds for believing that two is the typical number of pairs of these gonads in the Lumbricidae and Acanthodrilidae, and very likely in other terrestrial forms also. The fact that there , are two pairs of testes seems to render this assumption probable at least. In the genus Phreoryctes the number of ovaries (as of testes) is normally two pairs. Another fact pointing to the same conclusion is the presence in more than one species of Perichaeta of two pairs of egg-sacs; there is a pair in the fourteenth segment and another in many cases in the thirteenth segment; the latter would appear to correspond to a missing pair of ovaries belonging to the twelfth segment. In fact both lines of argument appear to point to the primitive possession of two pairs of ovaries at any rate in the terrestrial Oligochaeta. The passage of ova from the gonad into the duct and still more into the egg-sac in the terrestrial Oligochaeta is not easy to understand; as to the former it must be remembered that in the living worm the distance is not great between the gonad and the large mouth of the funnel; it is possible that from time to time during the movements of the worm the distance is lessened; when this takes place the oviducal funnel may approach so near to the gonad that the movement of its cilia may perhaps detach a perfectly ripe ovum from the extremity of the ovary and direct its course into the funnel, and THE ANATOMY. REPRODUCTIVE SYSTEM 87 thence either directly to the exterior or into the mouth of the egg-sac which lies conveniently near to the funnel. Among the Eudrilidae the passage of ova is enormously facilitated by the fact that the ovaries are enclosed in special peritoneal sacs which are continuous with the efferent duct; these sacs are late in their development, which seems to indicate their comparatively modern appearance; they were first discovered by myself in the genus Hudrilus (62); since that time they have been recognized in the majority of the Eudrilidae (which see for a more detailed description). Ova.—The parasitic and encysted Gregarines were at one time mistaken for the ova of Zwmbricus—perhaps not altogether an unnatural error. The ova are now known in a large number of Oligochaeta; but it is in Rhynchelmis that they have been most thoroughly studied (by VespovsKy). It is a remarkable fact that the Oligochaeta can be divided into two groups according to the character of their ova; in the aquatic Oligochaeta the eggs are large and contain an abundance of yolk; in the terrestrial forms, on the other hand, the ova are of microscopic size and contain but little yolk. It is, it will be observed, the large forms which have small eggs and broadly speaking the small forms which have large ova. All the genera which were grouped by CLAPAREDE within his group ‘Limicolae’ have large ova containing much yolk. Differences of size no doubt occur in both groups; but in no earth- worm is the egg ever so large as it is in the aquatic worm with the smallest ova. The difference is a remarkable one; it is almost, if not quite, as striking as that between the ova of a Mammal (not of course Prototherian) and a Frog. The large size of the ova was justly made use of by D'UDEKEM in his classification of the Oligochaeta. It is difficult to account for this striking difference; VEsDovsKY (24) pointed out that there is a difference in the mode of nutrition in the ova in the two groups; in the aquatic Oligochaeta the eggs are early detached from the ovary and undergo further ‘development in the body cavity or in egg-sacs; on the other hand, in earthworms the eggs reach maturity in the ovary which is furnished with abundant blood-vessels, which are wanting in the egg-sacs of the others; this latter statement is not quite accurate—at least in one way; it is perfectly true that there is no development of blood-capillaries on the egg-sacs of those worms; but special perivisceral vessels undergo an increase of length at the time that the egg-sacs are formed and accompany them. This cannot, however, be regarded as an explanation now; for in FLudrilus, and in the Eudrilidae generally, the eggs are apparently transferred at an early stage to the egg-sacs where they reach maturity; indeed, in some Eudrilidae the ovaries are even at an immature stage no longer to be found 88 OLIGOCHAETA in an ovary; they have been bodily transferred to the egg-sac. In Libyodrilus this appears to be the case; I succeeded in finding the ovaries in a very young worm, but not in mature or even in nearly mature specimens; no one has detected the ovary of Polytoreutus, though its position has been probably fixed with accuracy ; in Stuhlmannia, too, the mass of cells described by MICHAELSEN as an ovary may be one, but it has none of the characteristic appearances of germinal tissue; I am of opinion that this is to be explained on the assumption that all, or nearly all, of the germinal cells have been made over to the egg-sacs. The facts evidently require another explanation. It might be thought that there were differences in the development of the embryos sufficient to account for this. If, as one might perhaps infer from p'UDEKEM’s figures, the eggs when large and full of yolk completely filled the cocoon to the exclusion of any albumen, it would be at once apparent that the absence of a nutritive fluid necessitated other nutriment for the developing egg; but Vrspovsky has specially described the albumen in the cocoon of Rhynchelmis—an Oligochaet with very large ova. A free larval stage in one group or the other might also get over the difficulty; but there is none such; in all the Oligochaeta whose development is known—not a very large series it must be admitted, but still a series comprising representatives of genera with large and genera with small ova, the young leave the cocoon at approximately the same age; there are at least no striking differences in this particular. Among the vertebrata it is always possible to trace some connexion between the abundance of yolk in the ovum and the needs of the embryo; for example, the ova of Amphiowus have little yolk and are minute in size; this is correlated with the fact that the young are hatched in an immature condition; in the mammals there are of course special provisions (the placenta) to prevent the otherwise early hatching of the embryo; the frog which has much more yolk leaves the egg in a tolerably advanced stage of development; finally the bird and reptile is hatched in the practically adult condition. Nothing of the kind occurs in the Oligochaeta. I formerly attempted to show that there was truth in the idea that the nature of the ova is correlated with the habitat of the worm; the ova of Allwrus which is an aquatic form though related to the terrestrial genera are apparently larger than those of Lwmbricus; the difference, however, is not by any means an obvious one; moreover, I since found that the nearest approach to the ova of the ‘Limicolae’ among the Terricolae was to be seen in Moniligaster; here we have ova which are filled with large yolk spherules as large as those of, for instance, Tubifea; Moniligaster is purely a terrestrial genus so far as we know. The mature egg of Rhynchelmis, which may be selected as the type of a large THE ANATOMY. REPRODUCTIVE SYSTEM 89 yolked ovum, is spherical; it has a peripheral and extremely fine membrane, beneath which is a dense layer of protoplasm; connected with this is a protoplasmic net- work which ramifies through the entire egg and in the meshes of which are contained the yolk-spherules. The spherical nucleus is surrounded by a distinct doubly-contoured membrane. Around this membrane is a dense layer of protoplasm with a radial arrangement of its particles; but the membrane seems to be imper- forate. The contents of the nucleus show an obscure meshwork in the interstices of which is a granular nucleoplasm; there are as a rule two nucleoli, of a spherical contour; the substance of these can be differentiated into two layers; outside there is a radially striate coat within which is the granular core. The ovum is elaborately figured and described by Vespovsky, to whose work reference must be made for further details (9). Among the Megadrili the most aberrant ova are those of the Eudrilidae. Like other Megadrili they are of small size owing to the small development of the yolk. As in Lumbricus, there is a membrane covering the egg externally; but this membrane is greatly developed in many Eudrilids. In Lumbricus it is an excessively fine membrane as in Rhynchelmis; but in Hyperiodrilus there appear to be two distinct membranes. The ovum is surrounded by a very thick, darkly staining membrane which is traversed by numerous pores; beneath this is a fine membrane which I regard as the probable equivalent of the vitelline membrane of Lumbricus. The egg-protoplasm has a distinctly reticular arrangement, and the nucleus has also a membrane separating it off from the surrounding protoplasm. The ova of Heliodrilus appear to possess much the same structure. In £udrilus the ovum has a thick membrane, exactly like the thick outer membrane of the ovum of Hyperiodrilus in minute structure; but it has the remarkable peculiarity of being confined to one pole of the ovum; it does not extend right round, The structure of the ovum of this Annelid has been treated of by Horst and myself. Horst (8) speaks of this peculiar membrane as a protoplasmic mass formed of filaments which have the appearance of cilia. The membrane must, I think, in spite of the fact that it is only partial, be compared to that of Heliodrilus. The comparison seems to favour my opinion that the membrane in question is not a product of the ovum, but is produced by the modification’ of the follicular cells surrounding the growing egg. If it were a product of the egg protoplasm it would surely surround the entire circumference of the egg in Hudrilus no less than in Heliodrilus. I shall recur to this ‘membrane’ in describing the egg-development. Development of the ova.—There appear to be three types of egg-development in the Oligochaeta. 90 OLIGOCHAETA The more prevalent type is seen in all earthworms except certain Eudrilidae, and in a large number of the aquatic Oligochaeta; it is met with, for example, in the Lumbriculidae and most Tubificidae. Vuspovsky has described in great detail the facts for Rhynchelmis which I shall therefore take as an instance. The youngest eggs are indistinguishable from the mass of ovarian cells among which they lie in the egg-sacs; the cells appear to be amoeboid in their youngest stages; this is inferred from their frequent pear-shaped character and from the fact that they are not always in continuous contact. Any of these cells, it may be inferrred, may develop into ova. As the egg-cell grows its peculiar characters already described gradually differentiate themselves; the nucleolus is at first of course single and its bipartition has been observed; no share whatever appears to be taken in the development of the ovum by the surrounding cells; at any rate no changes are noted in them by Vespovsky. In Lumbricus the mature ovum has, what it has not in Rhynchelmis, a distinct follicular layer of flattened cells; it is possible that these cells dc bear a part in the maturation of the ovum; but apart from this follicle no changes are observable in the remaining cells of the ovary which are not on the way to become ova. The second method of egg-development differs from that just described in the important fact that certain of the cells of the ovary do apparently take a share in the formation of the ovum by contributing to its nutrition; this way of development has at present only been observed in Hudrilus by myself and Horst. Our observations agree in all essentials. The development here, as in Rhynchelmis and many other worms, takes place in the egg-sacs. At first the young ova are seen lying among a quantity of indifferent cells; any of these, it is to be presumed, possess the capability of becoming ova; later the cells in the immediate neighbourhood of the more mature ova gradually break down; the out- lines become obscured and the final stage reached is a mass of protoplasmic matter in which neither cells nor nuclei can be any longer recognized, and which has a fibrous appearance; it is very possible, though I have no positive facts to go upon, that the peculiar membrane already referred to as surrounding one pole of the ovum is produced by this broken down mass of cells. The pores of the membrane in question are figured by Horst as penetrating the vitelline membrane, and he thinks that they serve as the conduits of nourishment to the ovum. There is to my mind an undoubted resemblance in the mode of development of the ovum in Eudrilus to the formation of the Graaffian follicle in the higher Mammalia; in the latter, the liquor folliculi is produced by the breaking down of cells of the follicle, at least partly; and this liquid may be fairly compared to the perhaps fluid THE ANATOMY. REPRODUCTIVE SYSTEM 91 protoplasmic mass referred to as surrounding the mature and nearly mature ova of Eudrilus. The third mode of development of the ova in the Oligochaeta is especially interesting, as it appears to show great resemblances to the development of the spermatozoa in the same worms. It is characteristic of the Naids, the Enchytraeidae, the genera Ilyodrilus and Phreodrilus among the Tubificidae. It has been followed out by a good many observers; the eggs in these worms consist in their early stages of masses of cells, which become detached from the ovary, and either find their way into the egg-sacs or float freely in the body-cavity. Each mass consists of a peripheral row of cells surrounding a central mass of protoplasm, which has no nucleus and does not appear to be the equivalent of a cell. I have seen in Phreodrilus the whole mass surrounded by a layer of flattened cells. Later one of the cells increases in size and becomes a definite ovum; when it breaks away the other cells may in their turn become ova; in this case the development is almost exactly that of the spermatozoa, the only difference being that the peripheral row of cells are not simultaneously converted into sexual elements. In the early stages of the ovarian development of Ilyodrilus Stoic (8) represents the immature ova as not separated by distinct boundary lines from the central non-nucleated mass. The spermatozoa and their development.—The spermatozoa in the Oligochaeta are always filiform bodies and possess the power of free movement. As a general rule there is no thickening at one end; this was only observed by VEJDovsKY in the Lumbriculidae. The development of the spermatozoa has been studied by a large number of naturalists; the reader is referred to BLOOMFIELD and Nassz especially for details upon this subject. The principal facts appear to be the following; the sperm undergoes its development in the sperm-sacs in those worms (the majority) which possess these structures; the sperm mother-cells divide in such a way as to form a peripheral layer of cells, not at first marked off from a central, generally unnucleated mass of protoplasm; this latter has been termed the cytophore or the sperm-blastophore; this structure is simply the remains of the mother-cell, and possibly serves to nourish the growing spermatozoa; it is evidently to be compared to the central mass of protoplasm round which the ova of Phreodrilus, &c. are developed. § 2. Sperm-sacs. Nearly all the Oligochaeta possess sacs in which the sperm undergoes most of the stages of its development, and which are on that account termed sperm-sacs ; this name is preferable, on the whole, to the earlier name of ‘vesiculae seminales,’ N 2 92 OLIGOCHAETA because that term suggests a comparison with the similarly named structures of vertebrates, which are a part of the efferent apparatus; at first the structures now known to perform the function of harbouring the sperm were regarded as testes ; in spite of the discovery by Herine of the real testes, the sperm-sacs were persistently termed the testes by almost everybody. From the fact that the sperm-sacs always appear to contain Gregarines, these organs were once regarded as ovaries—the Gregarines when encysted being mistaken for the ova; D’'UDEKEM’s discovery of the ovaries disposed of this view as well as of the alternative view due to VON SIEBOLD that the sperm-sacs were hermaphrodite glands. Their true nature was first pointed out by Hertna who called them ‘Samen- blasen.’ The development (in Luwmbricus) was first elucidated by Berau, whose discoveries finally disposed of the theory that the organs were testes. The sperm- sacs originate from the intersegmental septa, as outgrowths of the same; they contain from the first a cavity which is continuous with the cavity of the segment from the wall of which they arise; this cavity is therefore coelomic; later on it is divided up into a series of inter-comrounicating spaces by the complicated growth of the walls; but none the less the internal cavity remains coelomic, and the epithelium found within it is peritoneum. The sperm-sacs are in fact coelomic sacs set apart for the maturation of the sperm. It is usual to distinguish between the paired sacs and median unpaired sacs which enclose, when present, the gonads, the ventral blood-vessel and even the nerve-cord, besides of course the funnels of the sperm-ducts. These communicate in the adult with the paired sacs; the name sperm-reservoirs may be applied to the former, that of sperm-sacs may be reserved for the latter. As to the origin of the sperm-reservoirs there does not appear to be much positive information; BLoomrieLp thinks that they are due to a coalescence between the paired sacs; BERGH is not apparently inclined to back up this view. It can hardly be doubted that they originate from the septa as do the paired sacs; they differ, however, in structure to a certain extent; the cavity of the paired sacs, as has already been stated, is subdivided into numerous cavities ; that of the median sacs is not so divided; the median sacs are by no means always present; they are absent, for example, in the genus Allolobophora; they seem also to be absent in Acanthodrilus and in a number of other forms. In these genera it of course follows that the gonads and the sperm-duct funnels hang freely into the cavity of their respective segments. It is not always possible to refer a given structure to one of these two series of sacs; the matter becomes easier if we agree to apply the term sperm-reservoirs to those sacs which enclose the gonads and the funnels, reserving the term sperm-sacs for diverticula of the septum which do not THE ANATOMY. REPRODUCTIVE SYSTEM 93 enclose these organs. Looking at the matter in this way, the sacs in Moniligaster must be regarded as sperm-reservoirs, although they are paired; the sacs in question enclose the gonads and the funnels, and it will also be noticed that their cavity is undivided by trabeculae—another feature which characterizes the sperm-reservoirs of Lumbricus in contradistinction to the sperm-sacs. It appears from the results obtained by BercH and Vespovsky that the paired sperm-sacs are developed before the median sacs; hence it would seem just to regard these sacs as older than the median sacs. It is conceivable that the median sperm-reservoirs of earthworms are more strictly comparable to the generally impaired and very voluminous sacs found in the aquatic Oligochaeta, than are the sperm-sacs. In only one family of Oligochaeta are the sperm-sacs nearly always absent, this family is the Enchytraeidae; the genus Mesen- chytraeus, however, has paired sperm-sacs, which originate from the septum bounding posteriorly the segment in which the male gonads lie. The number and arrangement of the sacs varies considerably in different genera, thus affording valuable characters which are sometimes of specific value only. The number of the sperm-sacs varies from one to four pairs. The aquatic forms have only a single pair or a single sac which usually extend through a large number of segments, enclosing the egg-sacs in many cases, as in Rhynchelmis figured by Vespovsky (9). In the terrestrial worms the sperm-sacs are as a rule of comparatively small size; they rarely occupy more than a single segment. There are various exceptions to this rule, however; and these exceptions always concern species or genera in which the number of the sperm- sacs is reduced to one pair. The most remarkable instances are Polytoreutus (Woodeut, fig. 26) and Z'richochaeta ; in both of these genera there is one pair of sperm-sacs which extend backwards through twenty or thirty segments; the extent of these sacs is only paralleled by certain aquatic genera such as Rhynchelmis. It POLYTOREUTUS. REPRODUCTIVE ORGANS. 1. Anterior end of sperm-sacs. 2. Dilated region of sperm-duct. 3. Calciferous gland. 4. Oviduct. 5. Spermi- ducal gland. 6. Sper- mathecal sac. 7. Pos- terior end of sperm-sac. is true that when the sperm-sacs are of such an extraordinary length they are thin; but in spite of this the total space enclosed by them is greater than in the case of the ‘genera where there are two or three pairs of sperm-sacs only, occupying a single segment each; unfortunately our knowledge of the economy of these worms does not at present permit of any explanation of these remarkable divergences. NeEvLAND has recently recurred to the earlier view respecting the sperm-sacs; he considers 94 OLIGOCHAETA that the sperm-sacs are to be regarded as a testis; but in putting forward this somewhat belated theory, the author has forgotten the development of the organs in question. However these are the grounds upon which the identity of the sperm-sacs with testes is based. The testes as first described by Herine were not always to be found in the situation where he described them; bodies identical in every particular with these testes—so much so that one might have served as a model for the other—were found in the sperm-sacs (‘Samenblasen- anhinge’). NrvLAND also points out that younger spermatogonia were found in the extremities of the sperm-sacs than in the more proximal regions; the reverse ought to be the case were the developing sperm-cells derived entirely from the testes (of HERING); the nearer to the testes the less advanced ought to be the spermatogonia. Hrrine has figured the mouth of the sperm-duct as nearer to the testes than to the mouth of the sperm-sacs; why therefore, asks NEULAND, does not the unripe sperm get into the latter? As is known this does not take place. Another matter raised by NEULAND is the immense amount of sperm produced—an amount too excessive to have been produced only by the testes of Herne. Even if it be true that germinal tissue is produced in the interior of the sperm-sacs—which as yet wants confirmation—it is not clear how this proves the contention that the sperm-sacs are testes; in a loose sense of the word they might be called so; but then so they might have been before, for the median sperm-reservoirs contain the true testes; no doubt the whole structure may be called a testis in the same sense that the testis of Astacus is so called, or even the testis of the vertebrate which contains besides the germinal tissue other structures. § 3. Hgg-sacs}. In the majority of Oligochaeta the ova when ripe or nearly ripe are transferred to certain sacs in which they remain for a time before being extruded from the body; these sacs are enormously developed in all the aquatic Oligochaeta, but appear . to be rudimentary structures in most of the terrestrial forms. In Rhynchelmis, for example, the egg-sacs extend back as far as to the fifty-fourth segment, or even in more mature individuals to the sixty-seventh. In other aquatic families similar sacs are to be found; they are comparatively as large in the Tubificidae and Naidomorpha. NassE has described their development in Tubifex: they originate as outgrowths of the dissepiment xi/xii; into these sacs the sperm-sacs are pushed as_ they develop; and thus in the mature worm we have two sacs one within the other, the outer of which contains ova and the inner sperm; the same is also the case with Rhynchelmis, where Vuspovsky (9) speaks of the egg-sacs and the sperm-sacs lying within and enclosed by a common membrane; it should be observed that these sacs are paired, lying one on each side of the intestine (see Vespovsky 9, Pl. III, fig. 1 0.8. fig. 2). But the egg-sacs are not always paired; in Stylaria proboscidea (cf. Tauser 2, Pl. XIV, fig. 1 0. v.), for instance, and in other Often called Receptacula ovorum. THE ANATOMY. REPRODUCTIVE SYSTEM. 95 Naidomorpha the egg-sac is a single structure surrounded anteriorly by the sperm- sac; the same statement holds good for other Oligochaeta, indeed for the majority of the aquatic forms; in Twbifex there is only a single sac, such too is the case with Mesenchytraeus. VEJDOVSKY (24) indeed seems to imply that unpaired sacs are the rule, for he states in a footnote to p. 137 of his ‘System und Morphologie’ that only in Rhynchelmis are the sperm-sacs, and, as we know, the egg-sacs, paired ; the remark in the text to which this footnote is appended runs as follows:—‘Sowohl die Samen- als Eiersicke sind unpaarig, &. The paired condition, however, seems to be usual in the Lumbriculidae, for it is met with in Sutroa as well as in Rhynchelmis; the formation of the egg-sacs in the aquatic Oligochaeta seems to be merely a pushing out of the septa, caused, perhaps, by purely mechanical reasons: i.e. the large size of the ova and the pressure which they must consequently exert as they are driven backwards by the development of those in front; I have figured in the genus Phreodrilus the first commencement of the egg-sac, where it is nothing more than a bulging of the septum (21 PI. II, fig. 31). The egg-sacs were generally termed ‘ovaries’ just as the sperm-sacs were called erroneously ‘testes’; the excuse for this error was in many cases the fact ‘that the ovaries in the sexually mature worm had entirely broken up into clumps of developing ova, leaving no trace of their former existence. Among the terrestrial genera it is only in the family Moniligastridae that the egg-sacs are at all large; here they may extend through three or four segments; they are always paired sacs and enclose the numerous ripe ova; as the Moniligas- tridae are the only earthworms with comparatively large ova loaded with abundant yolk, there almost appears to be some connexion between the large size of the egg-sacs and this fact; for in the aquatic Oligochaeta, also, the ova are loaded with yolk spherules. The minute egg-sacs of Lumbricus were first discovered by Herina who wrote as follows:—‘ Der innere Rand des Trichters reicht an den Darmkanal; am oberen Rande ist ein kleines, durch das Septum in den vierzehnten Ring hineinragendes Knétchen angewachsen. ... Am oberen Rande (der Tuba) stiilpt sich die Wand zu einem kurzen Fortsatz aus, der durch das Septum tritt und im vierzehnten Segmente mit einer blischenformigen Erweiterung endigt. Dieses ist das erwihnte Knétchen. Es zeigt eine sehr verschiedene Breite, durchschnittlich o'5 mm., und ist von einem dichten Gefassnetz umstrickt, dessen einzelne Gefasse bisweilen einen Durchmesser von 0:03 mm. erreichen. Unter dem Mikroscop ist es schwierig, den Zusammenhang dieses Organes mit der Tuba nachzuweisen, weil diese sich nicht von dem muskulésen Septum ganzlich isoliren lasst, so dass jedes klare Bild unmdglich 96 OLIGOCHAETA wird. Man kann indess jeden Zweifel dadurch heben, dass man bei méassiger Vergrosserung die natiirliche Spitze eines feinen Haares von der Tuba aus in das Blaschen eindringt. Dies gelingt ohne Schwierigkeit und man sieht unter dem Mikroscope deutlich wie die Haarspitze an der hinteren Wand des Blaschens angelangt sich umbiegt. In den meisten Fallen fand ich in demselben Eier, 1-5 an der Zahl, von gleicher Beschaffenheit und grdsser, als die im Ovarialzipfel enthaltenen und es liegt nahe, es als einen kleinen Kihalter anzusehen, in dem sich die Eier ansammeln, um dann gemeinschaftlich in eine Eikapsel entleert zu werden. Der grosse Gefassreichtum des Organes weist auf Absonderung einer Fliissigkeit hin, die vielleicht den Transport der Eier durch den Kileiter erleichtert. Der letztere ist ein mit zahlreichen Gefissen umstrickter Kanal, ausgekleidet von einem, &c.!’ The development of these egg-sacs in Lumbricus has been studied by BeReu (5); he has shown that they originate as thickenings of the septum xiii/xiv, which later become excavated and communicate with the cavity of the thirteenth segment by a small aperture; their interior is broken up, by anastomosing trabeculae, into numerous compartments which lodge the ova; the oviducal funnel just reaches the interior of the sperm egg-sac as is shown diagrammatically in the sketch given by Goruticu: this clearly facilitates the passage of eggs from the sac to the exterior. The investigations of BEercu already referred to have plainly shown that the egg-sacs are quite homologous structures to the sperm-sacs; both have the same minute structure and originate in the same way. The cavities of the egg-sacs are of course portions of the coelom, and they are lined like the rest of the coelom by peritoneal epithelium ; the rest of their walls is muscular tissue. In other genera of earthworms egg-sacs are to be found; but it is doubtful, in some cases at any rate, whether they have any function and are not rather to be regarded as rudimentary organs. Thus in Criodrilus egg-sacs exist; the ova found in the interior are according to CoLLIn® (1) smaller than the ripe ova within the ovary itself; this may argue that the ova become degenerate in the egg-sacs or perhaps that this sac is a sort of forcing house for the ova—only the comparatively unripe ova finding their way thither to attain maturity; the fact that the egg-sacs have abundant blood-vessels in their walls, which indeed often renders them + These egg-sacs were passed over by both LanKesrrr (8) and Craparbpe (1) in their accounts of the structure of Lumbricus; Horsr, on the other hand, has described and figured them (11). And they have been recognized by all subsequent observers. ? Who figures as an abnormality the egg-sac of one side of the body depending from septum xiii/xiv into the interior of the thirteenth segment. THE ANATOMY. EGG-SACS 97 extremely conspicuous to the naked eye in spite of their minute size, seems to indicate that they have some function. In the large and important family of the Eudrilidae there appear to be invariably a pair of egg-sacs present; but in every case the egg-sacs appear without doubt to be functional though they are no larger or but little larger than in Lumbricus; in this family the passage of ova into the egg-sacs is nearly always facilitated by peritoneal sacs, which enclose the ovaries and form a closed duct leading to the egg-sacs; I refer again to these in describing the Eudrilidae. In all the Eudrilidae the egg-sacs in mature individuals contain not merely ripe ova, but ova in various stages of development surrounded by masses of ovarian cells; this state of affairs is similar to what is found in the lower Oligochaeta, where masses of cells are broken off from the ovary and find their way into the egg-sacs, where they undergo further development; in these cases, therefore, there is a closer likeness as regards function between the egg-sacs and the sperm-sacs, for in both the genital products undergo at least the final stages of development; whereas in Lumbricus only ripe ova without any attached cells lie in the egg-sacs. One pair of egg-sacs have been found in the same segment (the fourteenth) in the Acanthodrilidae, the Cryptodrilidae, Geoscolicidae, and certain Perichaetidae; as a rule egg-sacs seem to be absent from the smaller and degenerate species; thus they do not appear to exist in Ocnerodrilus or in Gordiodrilus. In many Peri- chaetidae the egg-sacs are interesting from the fact that there are two pairs of them; I have pointed out that to the two pairs of testes correspond as a rule two pairs of sperm-sacs; now there does not appear to be any earthworm in which there are normally two pairs of ovaries, though in many there are traces of a second pair, especially in development!; we should expect, therefore, that originally, at any rate, two pairs of egg-sacs existed in correspondence to these two pairs of ovaries. And in the genus Perichaeta (s.s) there are several examples of species in which there are two pairs of egg-sacs. Bzrau (5) has remarked upon the presence of two pairs in a species nearly related to Horst’s Perichaeta hasselti; one pair occupy the normal position, the other lie in the thirteenth segment just above the ovaries; this is, it will be observed, precisely the position that the second pair ought to occupy, for the missing ovaries belong to the twelfth segment. I have found two pairs of egg-sacs in other species of Perichueta similarly placed. In Perichaeta I have noticed that these egg-sacs are often rather larger than in Lumbricus, and that they are of an elongated form perhaps more like the sperm-sacs in } See Woopwarp (1, 2) for occasional presence of many ovaries. 0 ® 98 OLIGOCHAETA shape than is usually the case; in considering the possibility that Perichaeta is an archaic type of earthworm, the existence of two pairs of egg-sacs is of some importance. Bsrcu found nothing in the egg-sacs of the species investigated by him but Pseudonavicellue and darkly pigmented bodies; he comments upon the fact that the funnel of the oviduct does not open into the interior of the eyg-sac as it does in Lumbricus, and suggests on this account that the bodies are functionless. They are certainly not always functionless in this group of earthworms ; I found in Diporochaeta intermedia a pair (one only) of egg-sacs in the usual position which were full of developing ova, each surrounded by a mass of nutritive cells; these egg-sacs had no communication with the oviducts, but the fact that they contained so many eggs, both fully mature and developing, seems to dispose of the view that, when there is no connexion with the oviduct, the egg-sacs are without function. In the species just referred to the egg-sacs contained abundant Gregarines which I have also met with in the egg-sacs of Eudrilus; this is another resemblance to the sperm-sacs, where these parasites are invariably to be seen. $4. Sperm-cducts. Special conduits for the semen are found in all Oligochaeta, with the sole exception of the genus Aeolosoma. In that worm, according to the recent researches’ of Srotc (1) true sperm-ducts do not exist; the nephridia of all the segments of the body conduct the spermatozoa to the exterior; this was proved by direct observation ; although the spermatozoa may escape by any of the nephridia (some of the nephridia disappear wholly or in part during the period of sexual maturity), those of the sixth and neighbouring segments especially take upon themselves the function of sperm-ducts, and they are figured by Srouc as rather larger than the others. When true sperm-ducts are developed there are never more than two pairs of them?; and frequently only a single pair exist. Hach sperm-duct consists of (1) a wide funnel-shaped opening into the coelom and (2) a tube more or less contorted which opens directly on to the exterior or through (3) a terminal chamber, the spermiducal gland, which will be described in the next section. Both the funnel and the tube are ciliated throughout. The funnel varies very much in form. In the simpler aquatic forms, and in some of the smaller terrestrial Oligochaeta, it is a flattened plate-shaped disc, with incurved and sometimes also } Pernier’s statement that there are no sperm-ducts in Anteus requires confirmation. ? Three have been described in Glyphidrilus weberi; but this is probably a ‘sport.’ THE ANATOMY. SPERM-DUCTS 99 a recurved margin. In the Enchytraeidae it has a very peculiar form; it is here barrel-shaped, with a lining of very thick glandular-looking cells, which encroach upon the lumen, reducing it to the smallest dimensions, Among earthworms the funnel is for the most part folded at the margins, whence the term ‘ciliated rosette’ which is often applied to it. The folding is often extremely complex. As a general rule the funnel of the sperm-duct opens directly into the general body cavity of the segment; sometimes, as in Lwmbricus, &c., the funnels are lodged in special sacs—shut off from the rest of the coelom—which contain the testes, and are in communication with the sperm-sacs. The funnels commonly lie close to the posterior septum of their segment, facing forwards and opposite to the testes which usually are attached to the anterior septum of the same segment; a curious exception to this rule is seen in the Eudrilid genera Teleudrilus, Hyperio- drilus, and Heliodrilus—perhaps also in some others. In these genera the funnels depend from the anterior septum of their segment, and accordingly (see woodcut, fig. 26) the vas deferens perforates this particular septum twice on its way to the ex- ternal pore. In the Lumbriculidae something of the same kind occurs, owing to the fact that the male genital pore lies in front of though in the same segment as the posterior funnels; these funnels face forwards and depend from the posterior septum of their segment as in the majority of the Oligochaeta; the vas deferens passes backwards perforating this septum and then again perforates it on its way to the external orifice. The number of funnels appears nearly always to correspond to the number of the testes ; if there is only a single pair of testes there is only a single pair of funnels and sperm- ducts; if there are two pairs of testes the number of funnels is' also doubled. The position of the funnels is also in correspondence with that of the testes, that is to say as to the number of the segment which they occupy. Very rarely this is not the case. For example in Heliodrilus the testes lie a segment in front of the funnels, which must necessarily occur owing to the facts already mentioned about the position of the funnels. The duct arising from the funnel is a tube with ciliated epithelial walls; the cells composing it are more or less quadrangular in form and surround the lumen which is never intracellular. Outside the epithelium is a layer of peritoneum and in a few instances, e.g. in Hudrilus, a layer of muscles between the two. Very anomalous are the sperm-ducts of Phreodrilus, where the windings of the duct, which has a caecal diverticulum, are largely within the peritoneal covering ; this is described more in detail below. The principal variations in the sperm-ducts 1 Not, however, apparently in many Lumbriculidae, where two pairs of funnels and one pair of testes. O02 100 OLIGOCHAETA concern (1) their position in the body, (2) the point of opening on to the exterior, (3) the degree to which the ducts of one side of the body are fused together. As a general rule the sperm-ducts lie in the body cavity; this is always the case in the lower Oligochaeta where they are frequently much coiled; even in the higher Oligochaeta (earthworms) where the ducts (except in Moniligaster) pass in an approximately straight course from funnel to pore, the sperm-ducts lie a little above the ventral parietes— In Lumbricus (cf. Neutanp, fig. 4) and other forms the sperm-ducts lie just within the peritoneum. The sperm-ducts lie deeper still within the tissues of the body-wall in a few other earthworms. I found this to be the case with Acanthodrilus annectens and have since recognized the same thing in Acanthodrilus paludosus and in a worm belonging to a totally different family, viz. Siphonogaster nvillsoni; in these examples as well as in Diplocardia communis (GARMAN, 1) the sperm-ducts are imbedded deep within the longitudinal muscular layer. It is quite possible that in other earthworms whose sperm-ducts have not been seen, the reason for their invisibility in a dissection is due to their lying in this position. Finally the genus Sparganophilus (Fam. Geoscolicidae) is unique by reason of the fact that the sperm-ducts lie deeper still or more superficially in reality. . They are placed just beneath the epidermis; in the clitellar region the duct lies at first below the entire epithelium; nearer to the pore it comes to be just underneath the superficial epidermis of the clitellum. The position of the external orifice differs greatly and is but rarely characteristic of a family. Asa general rule the two sperm-ducts of each side unite to form a single tube with a single orifice. In Phreoryctes, however, the two sperm-ducts open on to as many consecutive segments; they have absolutely no connexion with each other. An intermediate condition is to be seen in the genus Pelodrilus; here there are two quite separate sperm-ducts which, however, open near to each other on the same segment. In the Acanthodrilidae there is a still more marked foreshadowing of a fusion between the two sperm-ducts, for they join just before the external orifice. In the majority of earthworms, for example in the Perichaetidae, the two sperm-ducts join as soon as they can, i.e. in the twelfth segment. § 5. Oviducts. In the lower Oligochaeta there are no special conduits for the ova; the genus Aeolosoma is provided with a pore upon the median ventral surface of the sixth ‘* THE ANATOMY. OVIDUCTS 101 Segment; this pore has been figured by p'UpEKEM (2), and by Store (1), whose account, though establishing that of D’'UDEKeM, is more recent, and being the result of more refined methods of investigation is important if only as a confirmation of the earlier description. Among the Naidomorpha similar pores appear to exist. It is among the Enchytraeidae that we first meet with indications at least of special tubes which conduct the ova to the exterior; the structure of the oviducts in this group of the Oligochaeta is such as to suggest a degenerate condition. BucHHoLzZ controverted the opinion of D’'UDEKEM that the sperm-ducts served as the conduits for the ova also, and suggested that there might be simple pores in the skin through which the ova made their way to the exterior; such pores, however, were not found, though BucuHouz believed that they were probably small, owing to the ease with which the ova could alter their size. CLAPAREDE (8) described in Hnchytraeus vermicularis a pair of orifices upon the twelfth segment (this position is erroneous) ; these orifices were figured (Pl. IT. fig. 80) by CLAPAREDE as existing on the same segment as that which bears the male pores; this error is due to the fact that CLAPAREDE was not aware that the setae were absent on the segment which bears the male pores; hence he thought that the pair of setae behind the male pores belonged to that segment ; VEJDOVSKY (8) verified the existence of these pores by treating the living worm with a drop or two of Osmic acid which caused the pores in question to open widely and occasionally eggs were seen to pass out of them. They were, however, regarded as mere pores by VesJDovsky and by MIcHAELSEN (4) in his account of Hnchytraeus moebit. .MICHAELSEN, however, spoke of ‘trichterformige Einsenkungen des Dissepi- ments 12/13 in das 13. segment.’ And in his many subsequent papers upon this group of Oligochaeta he used the same expression. I have given (49) a figure of the oviducts of Pachydrilus; they appear to consist of a few pear-shaped cells, not ciliated, which fringe the orifices. The degeneration of these structures is curiously paralleled by the degeneration of the spermathecal duct in MNemerto- drilus, where an orifice only has been left fringed with very similar cells on its coelomic side. The oviducts in the Tubificidae and Lumbriculidae are very similar to each other, The curious belief that in the former the oviducts form a sheath to the spermiducal gland I deal with later. The oviducts in this family, so far as they are known, are, as in the Lumbriculidae, short tubes which open into the coelom by a wide funnel. It is in the earthworms that the oviducts form long tubes, but not everywhere. Generally, indeed, the large funnel is followed by a very short tube leading to the exterior. In such cases, e.g. Lwmbricus, Perichaeta, the oviduct is very little more 102 OLIGOCHAETA differentiated than in the Lumbriculidae. But among the Eudrilidae, for example in Libyodrilus, it is of considerable length, and not unfrequently possesses a muscular sheath. In Alvania it has even a caecum lying close to it and bound up within the same sheath. The position of the oviduct or oviducal pore, as the case may be, varies in different families. It is remarkable that in all Megadrili the oviducal ducts open on to the exterior in the fourteenth segment. Rhinodrilus proboscideus may be an exception, but the statement that the ovary lies in the seventeenth segment , requires confirmation. In Libyodrilus the oviducal pores appear to be on the fifteenth segment, but a dissection of the worm shows that the septum dividing the fourteenth and fifteenth segments lies behind the point of opening of the ducts. Considering the close agreement between the male and female gonads the differences between their ducts are perhaps more striking than the resemblances. There is the general agreement that both consist of ciliated tubes opening into the coelom by a wide funnel, often hidden within sperm-sacs or egg-sacs!. In both cases the ciliated tube consists of a single layer of cubical cells, which may be surrounded by a muscular layer in addition to the peritoneal coating. The caecum of the oviduct in Alvania may be compared to the caecum of the sperm-duct in Phreodrilus. In Phreoryctes too, which appears to me to be undoubtedly an archaic type, the oviducts and sperm-ducts (there are two pairs of each) not only correspond in number and structure, but the last pair of sperm-ducts is shorter than the first pair and is therefore intermediate in length between it and the oviduets. In the Microdrili, indeed, the sperm-ducts and the oviducts agree in never occupying more than two segments, the funnel lies in one segment and the external pore is in the following one or rather between the two, and there is a relation between the position of one orifice and the other (see Table above, p. 85). In the Megadrili the oviducts invariably occupy only two segments, while the sperm-ducts nearly as invariably? occupy more than two segments. There is, moreover, no ascertainable relation between the position of their pores, as the one varies, while the other remains fixedly constant. The coiling of the sperm-ducts is not paralleled by the oviducts; and the latter are never connected with glandular structures like the spermiducal glands. An apparent exception to this last statement is shown by Fudrilus, where the oviduct opens in common with the spermathecal sac and a glandular diverticulum apparently belonging to the same. This connexion, however, is probably hardly comparable to the connexion between sperm-ducts and spermiducal glands, since it is so rare among the Eudrilids (where alone it is found). ' Most completely in Eudrilidae. * One exception is probably Tetragonurus. \ THE ANATOMY. REPRODUCTIVE DUCTS 103 § 6. Development and Homology of the reproductive ducts. The generative ducts of the Oligochaeta have for a long time been believed to have some connexion with the nephridia, but the precise nature of this relation has only quite recently been cleared up; the oviducts are more like nephridia in the higher forms than are the sperm-ducts ; to begin with they occupy precisely the same number of segments as does a nephridium; the funnel opens into one segment and on the segment behind this is the external pore. This is also the case with the sperm-ducts of the Microdrili but not of the Megadrili. CLAPAREDE found that the genital ducts in the ‘Limicolae’ never coincided with nephridia and thus came to the conclusion that they were the modified equivalents of the latter. His observations turn out, however, to have been inaccurate; for, although in the adults of the worms there are no nephridia in the segments which contain the genital-ducts, the nepbridia are there in the immature worms, and only disappear on the appearance of the latter. The views of CLAPAREDE were extended to Lumbricus by LANKESTER, who pointed out that there was some evidence of the primitive existence of two pairs of nephridia per segment in that worm, one series being complete the other represented only by the genital ducts; the intimate relation between the nephridio- pores and the orifices of the genital ducts and the setae on the other hand led to this view, which was subsequently strongly supported by Perrier. This naturalist found that in some earthworms the nephridiopores were related to the dorsal instead of to the ventral setae as in Lumbricus, thus showing the persistence of the presumed second series of nephridia, the nephridia of Lwmbricus being only partially persistent in the genital ducts of those worms of which Antews was an instance. Later PERRIER found a worm (Plutellus) in which the nephridia alternated in position, now opening by the dorsal now by the ventral setae; in this case, therefore, the assumption was that both sets of nephridia partially persisted. The discovery of the occasional coincidence of a nephridium and a genital-duct at the same seta finally led PeRrizr to abandon the hypothesis. This difficulty was removed by my own discovery of the multiple nephridial pores of Octochaetus and other genera; and during the progress of Perrrer’s researches the discoveries of BALFouR and SEMPER of the connexion between the excretory and genital systems in the Vertebrata of course strengthened the views which favoured the probability of a similar connexion in the Oligochaeta, Nevertheless facts seemed to be against any such homology. The development of Lumbricus showed, or appeared to show, the entire independence of the two sets of structures (see BencH 5). On the other hand Sroxc, from his investigations into the anatomy of the sexual organs of the genus Aeolosoma, supported the view ; 104 OLIGOCHAETA he found that in that Annelid the male-ducts were represented by slightly enlarged nephridia; an argument derived from a study of the embryology of an Enchytraeid led Route to the same conclusion; he states that the segments in which the male- ducts will appear have no nephridia, but that the male-ducts appear rather late and so suggest the idea of a pair of slightly modified nephridia which are delayed in appearance in connexion with their changed function. Spencer and I at one time argued against the connexion between the excretory and genital-ducts from the ground that in Perichaeta, which we believed to represent a highly archaic form, the genital ducts showed no trace of their supposed origin from nephridia, the latter being in a very primitive condition. SpENnceR also pointed out that the genital ducts have an intercellular lumen while the nephridia have an intracellular lumen ; this argument is, however, at best not a strong one, and, as has been mentioned, VFJDOVSKY says that the lumen in the nephridia is really also intercellular. The only positive evidence as to a connexion between the nephridia and the genital-ducts has been brought forward by myself. In Octochaetus niultiporus the genital-ducts appear to be formed out of a part of the pronephridia, thus confirming the suggestion of BALFouR (Comp. Embryol. vol. ii. p. 617) that ‘in the generative segments of the Oligochaeta the excretory organs had at first both an excretory and a generative function, and that as a secondary result of this double function each of them has become split into two parts a generative and an excretory.’ The actual facts which I brought forward upon the development of the genital ducts are the following: at a comparatively late stage in the development of this worm, after the pronephridia have lost their distinctive character and have acquired numerous openings on to the exterior, the proximal part of the nephridium which consists of the remains of the funnel (the cilia have disappeared) and a straight tube leading to the body-wall separates off from the rest of the nephridium ; the funnel grows and re-acquires cilia; the tube grows into the body-wall and becomes the genital duct; the genital ducts have precisely the same structure at first whether they are to become oviducts or sperm-ducts; they are, moreover, only to be distinguished from the corresponding remains of the funnel and the first part of the nephridium in the preceding and succeeding segments by their larger size; it should be mentioned also that there are at first traces of four genital ducts in correspondence with the four gonads. It is very remarkable that in the case of four pairs only of the pronephridia the commencing degeneration should be arrested and growth recommence ; the tube, at first hollow, becomes solid and then re-acquires a lumen; an analogy to this state of affairs is, however, offered by the occlusion (temporary) of the lumen of the oesophagus in more than one Vertebrate. The disappearance followed by the reappearance of cilia upon the THE ANATOMY. SPERMIDUCAL GLANDS 105 funnels is also not without its analogies; particularly among the Protozoa where the vanishing of cilia so far from being an indication of degeneration is actually the prelude of renewed activity. In any case the facts appear to be as stated in Octochaetus. Another point to be emphasized in connexion with the development of the genital-ducts is their early appearance in Octochaetus as compared with Lumbricus. The facts which I have made out as to the development of the genital ducts in Octochaetus appear to absolutely contradict the facts established for Lumbricus —so much so, indeed, that it seems hardly credible that both can be correct. A little consideration, however, I think shows that there is not necessarily any contradiction. In Lumbricus the ducts appear after the nephridia have acquired their definite form; there is every reason, therefore, why they should not show any actual connexion with them in development, since presuming their homology with the genital ducts of Octochaetus the latter are formed out of the remains of a part of the pronephridia. The genital ducts of Lwmbricus are formed so late that they cannot be produced out of the pronephridia which have been in the meantime converted into the nephridia. Another point to be observed is that in Octochaetus the polynephric condition is to some extent established before the commencing differentiation of the sperm and oviducts. It is possible therefore to regard the existence of both in the same segment in Lumbricus as the last remnant of an ancestral condition where the nephridia were numerous in each segment. As tending to prove that in some ‘meganephric’ worms at any rate the funnels of the genital-ducts are formed out of the funnels of the pronephridia I may say that I could find no nephridial funnel in the tenth, eleventh, and thirteenth segments of Alvania millsoni, but I did find them in the fifth to ninth and in the twelfth and fourteenth segments. In Gordiodrilus there were none in the thirteenth at any rate. § 7. Spermiducal Glands}. In some Oligochaeta the sperm-ducts open on to the exterior directly; in others, and these are the majority, the sperm-ducts open into a wide terminal chamber which itself opens exteriorly; this is the case with the Lumbriculidae, the Tubificidae, the Perichaetidae, many Cryptodrilidae, the Eudrilidae, the Naidomorpha, the Chaeto- gastridae, the Moniligastridae, the Enchytraeidae; in a limited number of genera of Cryptodrilidae and in all the Acanthodrilidae there are these glands, but the sperm- ducts open separately on to the exterior though in their immediate neighbourhood. 11 prefer this name, recently suggested by myself (80) to either atrium or prostate as it emphasizes the position and relation of the glands, and having been never used before has no preconceived meaning attached to it. P 106 OLIGOCHAETA The Lumbriculidae, the Phreoryctidae, the Geoscolicidae (for the most part) have no such glands at all; and in these worms the sperm-duct is with a few exceptions un- provided with any glandular apparatus at its terminal orifice. The simplest form of the terminal chamber is found, as might be expected, in the lower aquatic Oligochaeta; in the Naids its structure is as follows: the sperm- ducts lead on each side of the body into a pear-shaped sac, which has been called the ‘atrium’ and opens on to the exterior in the sixth segment; this sac is lined by a glandular epithelium apparently without cilia; externally to this epithelium is a covering of peritoneal cells; the ‘atrium’ in Nais elinguis gradually passes into the sperm-duct; in Stylaria lacustris and in Dero there is an abrupt break between the two; I cannot discover any positive statements as to whether the lining cells are or are not ciliated in the Naidomorpha; there is no indication of any ciliation in the figures of Stoic (5) and Vespovsky (24). Among the Lumbriculidae we meet with a terminal chamber which is modelled upon the same plan as that of the last family. Among the Enchytraeidae there is very commonly a homologous organ of an equally simple, though rather different structure. I follow here MicHaELseEN’s account of L'nchytraeus humicultor.. It is a rounded or oval body (called by MicuarLsen a ‘ penis’), lined with long cells. It communicates with the exterior by a short invagination of the latter, which is beset with groups of unicellular glands. The sperm-duct opens at the summit of the terminal gland which has a muscular layer outside the lining epithelium. a The Tubificidae have an ‘atrium’ which is more complex than that of the last two families. In Tubifex itself, which may serve as a type of the family, the organ has been described by a large number of writers; it is an elongated sac receiving the sperm-duct at one end and opening on to the exterior at the other; the proximal part is ciliated; the distal region is MALE EFFERENT APPARATUS OF LOPHOCHAETA. ce (After Stole.) not ciliated; the latter forms a protrusible penis which is 1. Funnel, z. Penis. 3. ‘ : . hited i. erodinke described more fully in a separate section (see below). A 5 Coiled sperm-duct. remarkable feature of the atrium in the Tubificidae, with the exception of a few forms, is the presence of a glandular appendage variously termed ‘Cement gland’ (LanKEstER), ‘Cementdriise’ (VEsDovsky), ‘Prostate’ (Ersun, &c.);, this is a thick patch of pear-shaped glandular cells whose ducts (merely the pro- longation of the cells themselves) open into the lumen; Vespovsky has shown that THE ANATOMY. SPERMIDUCAL GLANDS 107 the origin of this body is an outgrowth of the lining epithelium of the atrium; it is a curious fact that the covering of peritoneum upon the atrium ceases at the point where the ‘prostate’ is attached, a fact which, if the development of these parts was not known, might give rise to the idea that the ‘prostate’ was nothing more nor less than a tract of peritoneum modified to serve a special function. Nass speaks iy ILYODRILUS COCCINEUS. MALE EFFERENT APPARATUS. BOTHRIONEURON VEJDOVSKYANUM. MALE EFFERENT APPARATUS. (After Stole.) 1, Funnel. 2. Sperm-duct. 3. Penis. (After stoke) 4 Muscles for its retraction. Be 1. Proximal region of ‘atrium.’ 2. ‘ Para- Glandular covering of 6. ‘Atrium.’ trium.’ 3 Distal region of ‘atrium.’ 4. Penial setae. 5. External pore. 6. Muscles for pro- trusion of distal end of efferent apparatus. 7. Muscle attached to sperm-duct (8). 9. Funnel. of a fine lumen to each group of cells in the prostate; but it is fairly clear that the gland is solid; the cells of which it is composed appear to correspond with other unicellular glands found so commonly among earthworms; for example, the capsulogenous glands of the Perichaetidae ; the ‘atrium’ being developmentally an involution from the outer layer of the body it is not remarkable to find P2 108 OLIGOCHAETA that gland-cells are developed in connexion with it just as gland-cells frequently underlie the epidermis. This form of atrium is found with but slight modifications in the majority of the genera of Tubificidae (woodcut, fig. 27); Ilyodrilus (woodcut, fig. 28) has, however, an atrium precisely similar to that of the Naidomorpha; in Bothrio- neuron and in Branchiwra the atrium is rather different, and the state of affairs characteristic of these two genera suggests another interpretation of the morphology of the parts in Tubifex; in both these last mentioned Tubificidae (woodcut, fig. 29) the vas deferens widens out into a terminal chamber which appears to be the atrium; but this is provided with a single lateral diverticulum (fig. 29, 2), very much larger in Branchiura than in Bothrioneuron; in Branchiura the lateral chamber has precisely the structure of the atrium in the Lumbriculidae. It is joined by the sperm-duct just where it passes into the muscular atrium; there can be no doubt in my opinion of the relationship between Branchiura and Tubifex; hence we should expect to be able to furnish a comparison of the different parts of the efferent ducts in each ; two views seem to be possible; either we must simply consider that the sperm-duct has come to open into the atrium some way from its extremity, or we must regard the sac-like appendix as the equivalent of the prostate of the typical Tubificidae; in this event the solid character of the prostate in the latter will be a secondary matter; Srotc (8) is apparently of opinion that the small lateral caecum attached to the atrium of Bothrionewron (called ‘paratrium’ by VEJDOVSKY) is the homologue of the prostate of other Tubificidae, as he indicates both by the same letters in his plates. The genus Telmatodrilus has an ‘atrium’ which is intermediate in character between that of Tubifew or Psammoryctes and the more typical Tubificidae on the one hand, and Branchiura and the Lumbriculidae on the other: in that genus Etsrn described and illustrated the presence of a series of separate ‘prostates’ opening at intervals through gaps of the proper walls of the ‘atrium’ into its interior; if these separate masses of glandular cells were combined into a continuous glandular structure we should have an ‘atrium’ exactly like that of Lumbriculidae, except for the absence of muscles. In the Megascolicidae the corresponding organ is constructed upon one or other of two types. In Acanthodrilus, for example, it is a tubular structure of varying length, occupying more or fewer segments, coiled or straight, which is divisible into two regions; the part of the tube which leads to the exterior is of less calibre and has generally a glittering appearance; this region serves as a duct for the glandular secretion of the distal region; it’is lined by a single layer of THE ANATOMY. SPERMIDUCAL GLANDS 109 non-glandular epithelium and has thick muscular walls; it is these which give the ‘Macreous” appearance already referred to; the glandular part of the tube is of greater calibre, and has an opaque white colour, and a rough exterior contrasting with the smooth external walls of the proximal part of the tube. This glandular section of the tube consists of two distinct layers of cells. The innermost coat is formed of a layer of not very deep columnar cells, often loaded with granules ; below these are several layers, forming a stratum of considerable thickness, of pear- shaped cells with long processes, which penetrate between the columnar cells and therefore abut upon the lumen, being thus in a position to pour their contents directly into the lumen; the entire structure of the lining epithelium is in fact very suggestive of that of the clitellum; there is the same specialization of its epithelium into two sorts of cells. Outside the epithelium is the peritoneal membrane. This kind of gland is found not only in the genus Acanthodrilus, but also in very nearly all the members of the family Acanthodrilidae; it also occurs in such Cryptodrilidae as have a tubular gland of a similar form to that of the Acanthodrilidae, with a few exceptions to be referred tv, and finally in a few Perichaetidae. There are hardly even differencies of the minutest character which distinguish the gland in these various types; sometimes the innermost epithelium is more plainly columnar and not so glandular as has been described; but this is very possibly merely a matter of more or less activity in the secreting processes. Ocnerodrilus (including a few allied genera which I group together near this) and Kerria are the only exceptions, among the Megascolicidae which have a gland of a tubular form, to the description just given; in these genera the difference is in the fact that the lining of the entire tube is formed by a single layer of cells only. The second form of the spermiducal gland seen in the Megascolicidae characterizes the Perichaetidae and is to be found in a large number of Cryptodrilidae ; it occurs only in one Acanthodrilid. Here we have first of all the same differentiation of the gland into a glandular and a non-glandular portion; the external duct is the non- glandular part and its length varies much in different species; certain species of Perichaeta, for example, are characterized by this duct being curved into a horseshoe- shape, and diminishing in calibre towards its external aperture; in others, on the contrary, it is short and straight; in none is it absent; it is, as in the case of the gland of the first kind, muscular, with a lining of columnar cells. In these worms the glandular part does not form a comparatively narrow tube of equal calibre throughout ; it has the appearance of a racemose gland much divided up into lobules ; the lobulation is sometimes so pronounced as to produce a very loose texture of the gland; sometimes the organ is more compact; it is also sometimes larger and some- 110 OLIGOCHAETA times smaller; in Perichaeta taprobanae, for example, the spermiducal gland is so small as to be entirely contained within one segment; in other species of Perichaeta it extends through a considerable number of segments. The peculiar appearance of the gland is produced by the branching of its lumen; the tubes are lined by low columnar epithelium which does not appear to be ever markedly glandular in character ; attached to the tubes are groups of pear-shaped cells inassed into bundles, whose fine processes seem to open into the lumen between the non-glandular cells which line it. It is this division of the lumen coupled with the grouping of the glandular pear- shaped cells that gives its peculiar appearance to the spermiducal gland in the Perichaetidae, &. The whole organ is covered with a fine covering of peritoneum. It will be evident from the figures illustrating the minute structure of the glands (woodcut, fig. 31) that there is no essential difference between this type and the tubular; the difference lies in the fact that in the Perichaetidae the single tube has become branched and the glandular lining has become grouped instead of remaining a con- tinuous layer; we find that genera very nearly allied in other particulars differ as to whether they possess a tubular or racemose spermiducal gland; besides, as I have pointed out, there are among the Perichaetidae glands which seem to be intermediate between the two extremes; the branching is much reduced and as a consequence the breaking up of the glandular cells into groups is not so marked. In the case of both kinds of glands the relations of the sperm-duct are pecu- liar; it never opens into the glandular part. As a rule the opening is into the muscular duct just at its commencement; this rule has apparently no exceptions in the Perichaetidae (see, however, the remarks upon Perichaeta ceylonica, below) ; it is, however, not so common among those genera which have the tubular variety of the gland; in Pontodrilus the sperm-duct has these relations; but in no member of the family Acanthodrilidae has the sperm-duct any direct connexion with the terminal gland at all. In every species it even opens on to a segment distinct from that which bears the orifice of the these; between this extreme and the other there are various intermediate stages; thus in Microscolea novae-zelandiae the sperm-ducts open into the spermiducal gland just before the latter opens on to the exterior; in Typhaeus the orifices are separate but are situated upon the same segment. There are as a rule but a single pair of glands in the Megascolicidae ; but exceptions are known; thus with the exception of Acanthodrilus monocystis the Acanthodrilidae have always two pairs opening on to the seventeenth and eighteenth segments; two pairs also characterize the genus Gordiodrilus. In the latter case they are in consecutive segments ; a unique disposition of the glands is afforded in the aberrant species of Perichaeta—P. ceylonica ; there are here two pairs, which are in the same segment a THE ANATOMY. SPERM!IDUCAL GLANDS 111 upon which presumably the sperm-ducts open (the eighteenth); the two glands of each side are, however, not similar to each other; one is of the tubular variety, the other like that of other Perichaetidae, i.e. ‘racemose. I was unable in examining this species to discover with which, if either, of the glands the sperm-duct was connected, Developmentally it might appear that the glandular part of the spermiducal gland is distinct from the duct; I have occasionally observed in immature Perichaetidae the duct alone present; and there are several species (Perichaeta masakatae, &c.) in which the glandular appendix never seems to put in an appearance. The Eudrilidae have a characteristic spermiducal gland. It is superficially like that of the Acanthodrilidae but really differs in a number of peculiarities, which together form one of the principal reasons for regarding the Eudrilidae as so distinct a family of Terricolae, and for removing it from the neighbourhood of the Cryptodrilidae. The gland has the same sausage-like form as in the Acanthodrilidae, but has almost always a nacreous glitter owing to its thick muscular coat. The main differences which distinguish the organ of the Eudrilidae from that of all Megascolicidae are :— (1) The usually thick muscular layer; (2) The opening of the sperm-ducts into the glandular part; The presence of a terminal muscular sac (bulbus). 3 P As a general rule the glands in the Eudrilidae are distinguishable, as they are in Acanthodrilus, &c., into a thicker glandular portion and a thinner duct, which is lined by a single layer of non-glandular cells. This is particularly well marked in the genus Hudrilus itself, where it has been figured by PERRIER and by myself (see woodcut, fig. 30). In Eudrilus the muscular duct is very slender indeed as compared with the glandular tube from which it arises. In a few other cases, however, there is no such abrupt transition. In Nemerto- drilus, for example, the gland gradually dwindles towards the extremity which bears the external pore; at the same time there is an increase, though a slight one, in the thickness of the muscular coat; and the lining epithelium becomes one layer. In Heliodrilus there is the same absence of any pronounced demarcation between the two sections of the tube, and the glandular lining becomes gradually one cell thick; it retains, however, its glandular character, being formed of large oval cells between which are narrow packing cells; but these disappear just before the opening into the terminal sac. 112 OLIGOCHAETA Eudrilus and Libyodrilus are among the genera whose spermiducal glands are furnished with very thick muscular walls; the fibres are arranged in two layers; the outermost, which is the thinnest, consists of longitudinally running fibres; it is these which give the nacreous appearance to the organ; inside the longitudinal is Fig. 30. » EUDRILUS. MALE EFFERENT ORGANS. ov. d, Sperm-ducts. pr. Spermiducal gland. au. Ap- pendices of terminal mus- cular sac, a thicker layer of circular fibres. In Nemertodrilus the muscular layer is greatly reduced, but it still consists of the two layers of fibres. The position of the opening of the sperm-ducts into the glands also varies considerably in different genera; they never, however, open either independently of them or into the terminal bulbus. The apparent opening is nearly always different from the real opening. For instance in Hudrilus (ef. woodcut, fig. 30) the two vasa deferentia pierce the walls at a point which is roughly half-way along the gland; microscopic sections, how- ever, show that the tubes run side by side between the muscular and epithelial walls of the gland to a point much nearer to its blind extremity, before opening into the lumen. In Libyodrilus the same thing occurs and the actual orifice is near to the very summit. Nemertodrilus occupies the opposite extreme in the series. The sperm-ducts here open into the glands nearer to the external pore. The third character of the spermiducal gland in these worms is also subject to some variation. The terminal bulbus is larger or smaller according to the genus. It is very conspicuous in Evdrilus and in Pareudrilus. In the former of these two genera it is a rounded sac which appears on dissection like a hemispherical thickening of the body-wall. From its internal walls arise two processes which, together with the peculiar U-shaped gland connected with one of them, will be referred to under the description of the penis of the Oligochaeta. At the opposite extreme perhaps is Heliodrilws, where the bulbus is reduced in size to be merely a slight depression of the external skin into which both the glands open. This terminal sac is protrusible and is generally found more or less protruded in individuals killed with alcohol. Finally, it should be mentioned that in Hudriloides brunneus, at any rate, tracts of epithelium in the glands are ciliated. THE ANATOMY. SPERMIDUCAL GLANDS 113 I select Kynotus michaelsenii as the type of the Geoscolicidae, as it has been very carefully described by Rosa, though unfortunately his description is unaccom- panied by any illustrations. The terminal apparatus of the male efferent ducts in this Annelid consist on each side of the body of a long oval muscular sac extending through four segments ; posteriorly and externally a long tube arises from this which reaches back through another seven segments; the terminal sac is attached to the parietes not only by its own walls, but by a moderately long muscular slip. The terminal sac has very thick walls, which as a consequence reduce the extent of the lumen; its interior is divided by an incomplete septum into two chambers; the upper of the two chambers is furnished with a shield-shaped thickening of the internal wall, on to which opens the glandular appendix to be presently described. The epithelium lining the ventral surface of the two chambers is like the external epidermis, but has rather more numerous glandular cells; the dorsal chamber, on the other hand, is lined by a tall columnar epithelium without glandular cells like those of the lower chamber, but with glandular cells staining deeply with carmine; the entire sac has a chitinous lining. The glandular appendix already spoken of opens on to the shield-shaped projection of the upper chamber; the canal which there opens has the same minute structure as that of the sac into which it opens; this becomes further back a tube lined with two layers of epithelium as in Acanthodrilus, &c., ensheathed in a common peritoneal coat which does not follow the windings of the contained tube. The sperm-ducts penetrate the terminal sac near to its external orifice and pass along the thickness of its wall, finally opening into the lumen of the glandular appendix where it retains the non-glandular character of the terminal sac. Rosa considers that the organ in the Geoscolicidae is not the homologue of that of other Oligochaeta and terms it ‘ Pseudo-prostate.’ It does not, however, appear to me to be possible to draw this hard and fast line between the Geoscolicidae and the Megascolicidae that Rosa wishes to draw; in the first place, as I have attempted to show, the Eudrilidae seem to agree more nearly with the Geoscolicidae than with the Megascolicidae; in both of them the essential difference is in the presence of a muscular terminal sac into which the spermiducal gland proper or the glands in the case of most Eudrilidae open. Rosa has, I think, overlooked the fact that in the genus Perichaeta something of the same kind also exists. In the systematic part of the present work I have laid some little stress as a specific character upon the fact that in some species the narrow muscular duct of the gland does not communicate directly with the exterior, but opens into the interior of a variously-sized sac; this latter may be of large size, as in Q OLIGOCHAETA 114 . y Perichaeta indica; or it may be almost absent, as in Perichaeta /lesperidum it is extrusible and ~ probably, though I have no positive data upon the subject, Fig. 31. SPHERMIDUCAL GLANDS OF VARIOUS OLIGOCHAETA. Eudrilus. E. D. Acanthodrilus. v.d, Vas deferens, C. Pontodritus. p. Peritoneum. uw. Glandular cells, m. Muscular layer B. Moniligaster. A. Sutroa. F, Perichaeta. G. Tubifex. b. Epithelial sp. Spermatozoa, lining of spermiducal gland. performs the function of a penis. In any case, whatever its function may be, it seems to be fairly comparable to the terminal muscular sac of the Eudrilidae and THE ANATOMY. SPERMIDUCAL GLANDS 115 the Geoscolicidae. No other genus of Megascolicidae, so far as I am aware, shows the same terminal sac; this fact is not without its importance; it is so far an indication that the Perichaetidae, having preserved this structure, are nearer to the Geoscolicidae and the Eudrilidae in which it is better developed than any other sub-family of the Megascolicidae. I use this as an argument in favour of the low position of the Perichaetidae in the series (see below). Another reason which led Rosa to dissociate the ‘pseudo-prostate’ of the Geoscolicidae from the ‘prostate’ of other earthworms was the existence of special retractor muscles in the former. These, however, are not absent from the latter. In the genus Octochaetus, for example, there are numerous bands of muscular tissue which are inserted on to the body-wall in the immediate neighbourhood of the male pores. A better example still is afforded by two species of Hudriloides (see BEDDARD 84), where there is a complex system of retractor and protractor muscles attached to the ducts of the glands themselves. It may be useful to tabulate the principal varieties of the spermiducal glands which are illustrated in the accompanying diagram (woodcut, fig. 31). A. Glands with a double lining of cells. a. Tubular, e.g. Acanthodrilus. 6. Racemose glands in which lumen has become branched and outer glandular layer of cells disposed in discrete tufts instead of forming a continuous layer. e.g. Perichaeta. A’. Tubular glands with a double lining of cells covered externally by a layer of muscles; terminal extremity modified into a copulatory apparatus. e.g. Budrilus, Kynotus. B. a. Spherical or more elongated glands with two layers of cells separated by a muscular layer. e.g. Rhynchelmis, Moniligaster, Branchiwra. b. Outer layer of cells grouped into separate masses. e.g. Sutroa, Telmatodrilus, Twbifex (one mass only present). C. Tubular glands with single lining of cells. e.g. Ocnerodrilus, Kerria. The structure which is here termed spermiducal gland has been called ‘ prostate’ and ‘atrium’ by several; the distinction of terms implies a difference in homology between the different appendages of the sperm-duct, which are by all called ‘atrium’ in the aquatic Oligochaeta. Does this difference really exist, or are all the glandular sacs at the end of the sperm-duct homologous throughout the Oligochaeta? I myself Q2 116 OLIGOCHAETA incline to the latter view, and will here state my reasons for so doing. The first reason which leads me to this opinion is entirely a priori; this is, however, in the present case a more powerful reason than it might be supposed to be, and than it would be perhaps in some other cases. The Oligochaeta so evidently form a single, well-definable group that the structures of the terrestrial forms may be confidently expected to be represented in the aquatic genera; at any rate we know of no structures which are peculiar to one or the other except those now in question. No one, I imagine, will doubt that all the structures called ‘atrium’ in the aquatic genera are homologous with one another. With inconsiderable exceptions these ‘atria’ receive the sperm-ducts; they have even been (erroneously) spoken of as an ‘enlarged part of the sperm-duct.’ In the Eudrilidae and in those Geoscolicidae, where they exist, the glandular tubes at the male pore also receive the sperm-ducts ; in Hudrilus itself, for example, the sperm-ducts open into the middle of the glandular tube; it can hardly be doubted that in this case we are dealing with a structure that does accurately correspond to the ‘atrium’ of the lower Oligochaeta. In the Acanthodrilidae, for instance, another arrangement occurs: here the structures which I have termed spermidueai glands open quite independently of the sperm-ducts, even on to a different segment; and yet the histology of the gland is in its main features quite like that of the Eudrilidae. The link between the two is afforded by a series of genera; in Pontodrilus the gland is not independent of the sperm-duct ; but the sperm-duct opens into the muscular duct and not, as in the Eudrilidae, into the glandular region; in Typhaews and in Microscolex the sperm-duct only communicates with the gland just before the opening of the latter on to the exterior; in Gordiodrilus the external pore of the gland is perfectly distinct from the pore of the sperm-duct but is placed upon the same segment; there are thus various intermediate conditions between the extremes. It can hardly be doubted that these latter genera possess organs which are homologous in spite of the rather different relation of the sperm-duct to them: in the Eudrilidae themselves the position of the opening of the sperm-duct into the gland varies in different genera. To insist upon a ditference between the spermiducal gland of the Eudrilidae and that of the Acanthodrilidae, because in one there is a direct connexion between it and the sperm-duct, and in the other there is not, seems to me from a consideration of the intermediate stages to be absurd; and if we apply this argument to the aquatic Oligochaeta the absurdity is even more apparent. In the genus Branchiura which I have recently described, the ‘atrium’ is appended as a diverticulum to the sperm- duct; the two open in common, but the ‘atrium’ does not receive the sperm-duct at its summit, but at the point where it passes into a muscular duct which leads to THE ANATOMY. SPERMIDUCAL GLANDS 117 the exterior; in spite of this difference, who could deny that the structure which I have called ‘atrium’ in Branchiwra is the exact homologue of the ‘atrium’ in other Tubificidae? To suppose that two structures so similar and yet morphologically different could exist in the genera of a limited family like that of the Tubificidae is to suppose too much, and to go counter to plain facts. Still, if BENHAM was right in calling the gland appended to the male duct in Pontodrilus ‘ prostate,’ and the similar gland in Hudrilus ‘atrium, it will be necessary to explain how it is that structures which are of different morphological import have come to possess an almost identical structure. And if the term ‘prostate’ is retained ‘for those glands which either pour their secretion. into the sperm-duct or open independently to the exterior, then the structure which I have called ‘atrium’ in Branchiura cannot be the homologue of the ‘atrium’ in other Tubificidae and Lumbriculidae. This appears to me the reductio ad absurdum, and to dispose of the necessity for further argument. There has been, however, some little confusion as to the meaning to be attached to the term ‘prostate, independently of the facts already referred to. I have called the glandular investment of the ‘atrium’ in the Lumbriculidae ‘prostate, and compared this glandular investment to the ‘Cementdriisen’ of Tubifex: it may be that I have, as BENHAM suggested, compared together structures which cannot be compared, since they are respectively epiblastic and mesoblastic in origin; in any case I did not seriously make that comparison after deliberation; I am now inclined to think that that comparison is after all the right one, provided only that embryology confirms it. The glandular investment of the ‘atrium’ in the Lumbriculidae does not appear to be peritoneal; we cannot, however, be certain, though it is so exactly like the glandular investment of the ‘atrium’ in Mondigaster which is probably not peritoneal. I have seen sections through the ‘atrium’ of Mondligaster in which the thick layer of cells investing it externally is covered by a thin layer of what is undoubted peritoneum; and there is no doubt that the layer of cells in question opens by prolongations of the cells into the lumen of the gland—a state of affairs which is not suggestive of its being in reality peritoneum, as I at first believed it to be. VEsDOVSKY, too, has figured a similar prolongation of the cells of the glandular coating of the ‘atrium’ in Rhynchelmiis to join the lumen’; the same thing undoubtedly exists in Sutroa; in all these cases, therefore, I believe that we have to do with a second layer of epithelium of epiblastic origin; the absence, if it be ultimately proved, of a peritoneal layer in certain Lumbriculidae, and in some species of Moniligaster does not appear to be a matter of the greatest consequence, since in ‘ Moreover, Bennam has described a delicate membrane surrounding the pear-shaped cells which is probably the coelomic epithelium. 118 OLIGOCHAETA the ‘atrium’ of Tubifex the peritoneum is absent from the ‘Cementdriise, which has been shown by VeEsDovsky to be an outgrowth of the lining membrane. I would therefore compare the ‘Cementdriise’ of Twbifex to a portion of the glandular investment of the atrium in such forms as the Lumbriculidae!; this view of the relations of the different parts brings matters into a far more satisfactory condition ; and it helps us also to get a clearer insight into the meaning of the apparently great difference between the spermiducal gland of the Perichaetidae and the Acan- thodrilidae—in fact to compare more readily the ‘lobate’ with the ‘tubular’ form; in the class of gland which I have termed ‘lobate’ the lumen is much branched, and the outer layer of glandular pear-shaped cells, instead of forming as it does in the Acanthodrilidae, and in other genera which have the tubular form, a continuous covering is broken up into masses of cells; now we get something very much like this in the genus Telmatodrilus among the Tubificidae, and in Sutrow among the Lumbriculidae; but in neither of these genera is there any corresponding branching of the lumen of the gland itself. Those Perichaetidae in which the gland is the most compact, in which the branching is not so conspicuous, show the earlier stages in the conversion of a tubular into a lobate gland—for example, Megascolex newcombei, while Diplocardia is an almost ideal intermediate form; there is in fact no difficulty in getting the one form of spermiducal gland out of the other. I have now to consider certain points in the histology of the glands which might seem to militate against a comparison between those of the aquatic and the terrestrial genera. In the former the cavity is lined by a single layer of cells often ciliated, which are separated by a layer of muscles from the outer layer of cells which have been spoken of by some as ‘prostates.’ In the terrestrial Oligochaeta, on the other hand, with a tubular spermiducal gland, the lining membrane is with a few exceptions always composed of two distinct layers; its resemblance in fact to the clitellum has been often insisted upon; I was inclined at one time to contrast these two forms, and to connect the resemblance of the spermiducal gland of the higher Oligochaeta with the clitellum with its origin from the clitellar region of the body: I do not now think that the difference is a real one; in such genera as Moniligaster it seems to me merely that the inner epithelial layer has been removed a little way from the other layer, so that a layer of muscle has come to intervene; just as certain glandular cells, undoubtedly of epidermic origin, have come to be imbedded in the musculature of the body-wall; the two cases seem to me to be perfectly parallel. This view of the matter has been put forward by Rosa 1 These views with regard to the homologies of differently named structures are now those of Brenuam (25) as well as of myself (80). THE ANATOMY. SPERMIDUCAL GLANDS 119 (4, p. 385) with regard to Desmogaster : he pointed out that in the worm the oute- layer of glandular cells were imbedded in a stratum of muscle, and that the atrium was so far intermediate between that of Moniligaster and Acanthodrilus, &e.; the muscles had not quite got to divide the two epithelial layers clearly from each other, Still, of course, this does not take away from the closer resemblance of the gland of Moniligaster to that of the Lumbriculidae than to that of the terrestrial earthworms. The occasional though rare ciliation of the lining epithelium in Eudrilidae removes all the differences that separate the spermiducal gland of the higher from that of the lower Oligochaeta. It will be seen therefore that the ‘prostate’ of Perichaetu may be safely compared with the ‘Cementdriise’ of Tubifex without doing any harm ; but that the insistance upon this homology must not be carried so far as to obscure the other obvious relations between the spermiducal glands of different forms. A question which now requires consideration is the origin of the spermiducal glands; are they to be regarded simply as dilatations on the sperm-duct or as separate structures which have come to have a relation to the sperm-ducts? I incline to the latter view. The chief reason which leads me to take up this position is the existence of supplementary glands which have no relation to the sperm- ducts; in Dichogaster damonis the two segments following that upon which the sperm-ducts open are each furnished with a pair of tubular glands exactly like the spermiducal glands in structure, but rather smaller: it is also remarkable to find that these two pairs of glands open on to the exterior in exactly the same position as those of the seventeenth segment, and that the ventral setae of their segments, as of the seventeenth, are missing; nothing in fact is wanting to complete their likeness to spermiducal glands, except that they have no direct relation to the sperm-ducts. The occasional presence of two pairs of glands to only a single pair of male pores, as we find in Acanthodrilus, Gordiodrilus, and Perichaeta ceylonica, is not so remarkable, for in all these worms there are two pairs of distinct sperm-ducts, although they become one at the external pore. This view of the origin of the glands is the one held by Rosa; in a paper upon the structure of Kynotus michaelsenit this author refers the spermiducal glands to the same category as certain glands found in that species in the segment following, and showing exactly the same minute structure. These glands are accompanied by penial setae. Rosa, it should be stated, is not of opinion that this view can be applied to the glands of other earth-worms; he is only considering the Geoscolicidae, which according to him have ‘ pseudo-prostates,’ not comparable to the apparently similar glands in the Oligochaeta generally; this opinion of Rosa’s is not one that commends itself to me, and I have 120 OLIGOCHAETA already attempted to show that the spermiducal glands in the Geoscolicidae are like those of the Eudrilidae more than any other group. In Microcheta benhami, also, there are a series of quite analogous glands which are referred by Rosa to the same category as the spermiducal gland; he also holds this view with respect to the posterior glands of Pontoscolex, Urobenus, and Brachydrilus ; as regards this latter comparison I may point out that the connexion of the glands of Pontoscolex with the nephridia is curiously paralleled by the connexion of the spermiducal gland of Heliodrilus with the nephridia of its segment; this connexion, however, may not be more than accidental in the latter case. The existence of this relation, especially in Pontoscolex, suggests that perhaps Rosa has not gone quite far enough back in seeking for the origin of the glands. It may be that the glands, with which I think with Rosa that the spermiducal glands are homologous, are themselves derived from the nephridia; as we now know that the sperm-ducts are homologous with nephridia, the connexion of the sperm-ducts with the spermiducal glands may be in this case comparable to the connexion of the nephridia of Pontoscolea with the posterior glands; this, however, does away with the significance of the connexion between the two in Heliodrilus. The glands in Kynotus lying behind the spermiducal glands are provided with modified setae, and thus the resemblance to the spermiducal glands, as they usually are, is completed; we must not, perhaps, leave out of consideration the anteriorly situated glands, also provided with modified setae in a few species of Acanthodrilus (s.1.), &c.; these are very likely to be placed in the same category. It is possible that the glands which are so often found in the neighbourhood of the male pores and the spermathecal pores in the Perichaetidae should be also referred to the same series; but it may be remembered that these latter have no lumen, and would therefore, have to be looked upon as much degenerated. Still their frequently paired arrangement, corresponding to that of spermiducal glands, is an argument to be borne in mind. The spermathecae also suggest the same origin, but I deal with their homologies under the heading ‘Spermathecae’ (see below). Closely connected with the last question, and, of course, with the phylogeny of the Oligochaeta, is another question: what is the most primitive form of the spermiducal gland? If we accept their serial homology with the copulatory glands it is evident that those spermiducal glands which are structurally most like the copulatory glands will have to stand at the base of the series. It should be noted in the first place that there seems to be a certain relation between the copulatory glands and the spermiducal glands in those few forms in which they coexist; that is to say, differences in the structure of the copulatory glands are repeated in the spermiducal glands. In Kynotus both glands have a muscular covering; in THE ANATOMY. GENITAL SETAE 121 Acanthodrilus both are without it; so too in Dichogaster damonis. The question, therefore, of the origin of the spermiducal glands is bound up with that of the copulatory glands, and must be deferred until we can determine which is the most primitive type of copulatory gland. It seems reasonable to suppose that the copulatory glands were originally modified tracts of the body-wall, which became invaginated and furnished with penial setae for their greater efficiency; the invagination, as it appears to me, might or might not involve the muscular layers of the body-wall; so that very probably both circumstances have occurred, which would account for the corre- spondence, noted above, between the copulatory and spermiducal glands. In this case the spermiducal glands of the Geoscolicidae might be equally primitive with those of the Megascolicidae. Another point, which has to be taken into consideration, is the relationship of the sperm-duct to the spermiducal gland. The independence of the sperm-duct and the gland is, ex hypothesi, a primitive condition. This suggests that the Geoscolicidae, and particularly the Acanthodrilidae, Perichaeta ceylonica, and Dichogaster are primitive forms. The spermiducal gland of Moniligaster, which is characterized by the transference of the gland-cells to the outer side of the muscular layer, seems to be a later stage in the evolution of the organ than that found in the Eudrilidae. § 8. Genital setae. In the neighbourhood of the male-pores there are in some Oligochaeta bundles of long modified setae which protrude through the orifices in question; to these structures the name of penial setae was first applied by Lanxesrer (1). In a very few species there are bundles of quite similar setae developed in the neighbourhood of the spermathecae, and in a few Geoscolicids, again, similar setae are found, not only at the male-pores, but on a greater or less number of segments in their immediate vicinity. Horst has proposed to limit the name penial setae to those setae which occur in the neighbourhood of the male-pores, and to call copulatory setae those which are found in the vicinity of the spermathecae. It is perhaps more convenient to apply the term ‘genital setae’ to all alike. These setae are nearly always found associated with glandular structures; in the case of those which protrude through the male-pores, there are, of course, the spermiducal glands with which they are more particularly associated; the sacs which contain them are often or at any rate have the appearance of being, diverticula of the spermiducal glands. The setae which occur in the neighbourhood of the spermathecae have special glands developed in connexion with them, which are described in the section devoted to the spermathecae. The special setae developed R 122 OLIGOCHAETA in various Geoscolicidae are nearly or always so accompanied by glands. This obviously suggests some relation between the setae and the glands. It looks as if the long setae had the function of either conveying by capillary attraction the secretion of the glands or opening wider an aperture for the passage of the secretion. It seems likely that that is the function of those setae which are developed in the neighbourhood of the male-pores, perhaps more specially those in which the spermi- ducal glands and sperm-ducts open by a common pore; they would facilitate the passing of the sperm and the secretion of the spermiducal glands. In the Acantho- drilidae, on the other hand, where the spermiducal glands open at some little distance from the sperm-ducts, the function would seem to be rather that of grappling the integument in the neighbourhood of the spermathecal pores in another individual ; here, however, it is possible that the sperm, when liberated from the male-pore may flow along the groove which connects this pore with those of the spermiducal glands, and may at these points mix with the secretion of the spermiducal glands, and be with it conveyed to the spermathecae of the other individual. Genital setae associated with the male-pores only occur in the Megascolicidae, the Eudrilidae, and (rarely) in the Geoscolicidae, Lumbriculides; in fact, they only occur in those families of terrestrial Oligochaeta in which the male-pores are provided with spermi- ducal glands. They do not, however, often occur in the aquatic families which have also such glands. Though their range of occurrence is thus a wide one, they really are found in comparatively few species; it is unnecessary here to give a list, which can be compiled from an inspection of the systematic part of this work. Naturally, » too, the exact shape of the setae differs; but in most cases the extremity is beset with spines, a state of affairs, however, which, is by no means universal; in many species of Acanthodrilus, for instance, the penial setae are quite smooth throughout. It is an interesting question as to whether these genital setae are new and special structures, or whether they are to be derived from the ordinary setae of the body which have become modified and converted to a new function. The second alternative is evidently the one which is most likely on a priori ground to be true; and, as a matter of fact, I believe it to be the true view of the origin of the setae. It will be noticed in the first place that when such modified setae are present the ordinary setae are wanting; they are present in the immature worms, but drop out when the genital setae make their appearance; and the genital setae as a rule occupy exactly the place of the missing ordinary setae. There are, too, not wanting transitional forms between the ordinary setae of the body and the modified genital setae; I have pointed out in Octochaetus antarcticus that the genital setae are much less specialized than in the nearly allied Octochaetus multiporus. On the whole, THE ANATOMY. GENITAL SETAE 123 therefore, it seems reasonable to regard the genital setae as being the modified representatives of the ordinary setae which should occupy their place. But another question requires answering: the bundles of genital setae generally contain more fully developed setae than would usually be present; not, of course, in the genus Megascolex, but in such a genus as Acanthodrilus. I have suggested that this points to the former perichaetous condition, a number of setae having been retained for the purpose of serving this new function. Though this view has not met with acceptance, there are other considerations which seem to me to favour it. In Perionya, as it appears to me, we have an early stage in the development of the genital setae preserved. In that genus there is (in some species) a row of the more ventrally placed setae, which are modified in structure, being beset with ridges at the distal end and being somewhat larger than the ordinary setae, which are smooth. _ These setae are sometimes imbedded in a groove into which opens the male-pore on each side; if this groove were withdrawn, so as to convert it into a more strongly marked recess, it would follow that the setae would be crowded together, as is the case with the genital setae of the other genera, and that they would at the same time tend to become longer, in order to be capable of projecting out of the invagination in which they are imbedded. This suggestion is to my mind reinforced by the distribution of genital setae associated with the sperm-duct apertures; they occur in the Meégascolicidae in bundles; the setae are numerous, though varying in number. Now it is at least arguable that all the worms belonging to this family are traceable to a form with a complete circle of setae. On the other hand, in the Eudrilidae the penial setae are not in bundles; there is only a single seta so modified on each side of the body; and this family is one in which perhaps the evidence of a descent from some form like Perichaeta is least arguable among the terrestrial Oligochaeta. It is true that the Geoscolicidae seem to be opposed to this way of regarding the matter. I am on other grounds disposed to connect them closely with the Eudrilidae, and this view of their affinities undoubtedly affords a way out of the difficulty. As will be seen later, I believe that the aquatic Oligochaeta are not near to the terrestrial; and it will be noticed that in none of these that have paired setae are there bundles of genital setae. A curious fact has been observed in a few earthworms, for example in Benhamia annae, and in other Acanthodrilidae, and that is that the penial setae in a single bundle are of two kinds; there are setae with an extremity marked by the presence of spines, and others in which the extremity is quite smooth; that both kinds of setae are fully mature, that the one kind are not the immature kind of the other, seems to be proved by their being of the same size. R2 124 OLIGOCHAETA \ $9. Penis. The presence of a copulatory organ, more or less analogous to the vertebrate penis, is not uncommon among the Oligochaeta. These organs may be single or paired, retractile or non-retractile. Sometimes they are directly connected with the male-ducts which open in them or on them; more rarely they have no such close connexion. In the preceding section, dealing with the spermiducal glands of the Oligochaeta, I have described the terminal part of these glands, which is almost always of a muscular nature; in many worms this part of the tube is partly protrusible, perhaps it is so in most; I have Fig. 32. found that it certainly is so in Peri- chaeta houlleti, where a number of specimens killed with alcohol had the terminal part of the muscular ducts of the spermiducal glands everted; I have not noticed the occurrence of this in any allied forms, but it very possibly takes place. In some “s.\ Perichaetae the muscular duct of ') the spermiducal glands opens into a wide and rather thin-walled terminal chamber, which opens directly on to . the exterior; it is here, again, possible that this terminal chamber is pro- trusible; but I have no facts at hand to prove or disprove the possibility. In most Eudrilidae the two spermi- TERMINAL EFFERENT APPARATUS OF EUDRILUS. ducal glands open into a single or pr. Spermiducal gland. v.d. Sperm-duct. , Penis, and paired terminal copulatory apparatus, ¢. Cushion like pad in interior of ‘Bursa, copulatrix’ which has been cut open. which may be fairly termed a penis. This structure, as has already been pointed out, varies much in its development from genus to genus. It is very well developed in Hudrilus; in that Annelid the terminal apparatus consists of a widish chamber, opening directly on to the exterior; into this chamber open first the spermiducal gland, and secondly the peculiar horseshoe-shaped ‘glands’ which are figured in the accompanying woodcut (fig. 32). The spermiducal glands open on to THE ANATOMY. PENIS 125 a kind of penis (p), which projects into the interior of the terminal chamber. It seems quite reasonable to suppose that the chamber can be everted; in which case the projection which bears the aperture of the spermiducal gland will play the part of a penis. In all Eudrilids there is something of the same kind, but the details differ; the structures are described under the account of that family. Moniligaster—at any rate one species of that genus—has a penis which is a little different, though it agrees in being retractile. The muscular end of the spermiducal gland does not open directly on to the exterior, but into a terminal chamber whose walls are reflected round it; we have, in fact, in this genus, an arrangement which is closely paralleled in the Tubificidae, and not very remote from the arrangement met with in Eudrilus. In the genera Stylodrilus, Allwroides, Stuhlmanma, Alvania, Hyperiodrilus, and Siphonogaster, there are penes of quite a different nature. In all these worms, which, it will be observed, belong to three different families, the penis or penes are non- retractile; they are processes of the body-wall, which may or may not have an intimate relation to the aperture of the sperm-ducts. It will be necessary to describe them one by one. Of Stylodrilus the penis has been described by VEspovsky and Brenuam. In Stylodrilus gabretae the two penes are figured by the former as longish, hollow processes of the body, whose walls are cellular; they communicate directly with the spermiducal glands, of which they appear to be merely a continuation, but they are not retractile. The recently-described genus Allwroides, from East Africa, has a pair of penes which are clearly outgrowths of the body-wall; they are placed, moreover, above the, opening of the male-ducts; they are peculiar in form, inasmuch as they are rather thick processes, hardly tapering at the extremity, which, in the preserved examples of the worm, are folded in an irregular fashion; the organ, though not retractile, seems to, be probably contractile, as the shape which it assumed in the preserved worms was hardly such as to ensure its usefulness as an organ for transferring sperm to the spermathecae. . The penis of Stuhimannia has been figured, as regards its naked eye characters, by MicuaE.sen (6). Its varying position is not a little remarkable; but it always lies somewhere near to the male-pore, and is at any rate connected with that pore by a groove in the skin. In transverse sections of the body-wall (see Plate IV), the penis is seen to be asymmetrical in structure ; it is roughly conical in outline; one side is covered by a thick glandular epithelium; the other side is covered by an 126 OLIGOCHAETA unmodified epithelium, which is like the ordinary epidermis. The interior of the organ is occupied by a quantity of laxly-arranged muscular tissue. In connexion with the penis there is developed a long sausage-shaped body of a nacreous aspect; this gland is covered by very thick muscular walls, and is lined by not particularly glandular epithelium. It narrows towards the external pore, which is situated on that side of the penis which is covered by thick epidermis. The penis does not always appear to be developed; I have examined a considerable number of sexually mature individuals in which I could find no traces of a penis. The penis here seems to be not much more than an outpushing of a part of the body-wall; the muscular sac connected with it may be the equivalent of the bursa copulatrix in Teleudrilus, divorced from its connexion with the rest of the terminal male efferent apparatus. In the genus Hyperiodrilus there are a pair of penes, which are connected by grooves with the male-pore; these penes are, as in Stuhlmannia, variable in position; they sometimes lie on the same segment as that which bears the male- pore, sometimes they are a segment in front, and in the latter case they are usually at least asymmetrical. In my description of Hyperiodrilus I described these structures as papillae; I think that they are more comparable with the penis of Stuhlmanma, with which, indeed, I compared them. There are no details as to the minute structure. The penis of Siphonogaster is described under the genus. § to. Spermathecae. The spermathecae are very characteristic organs of the Oligochaeta; it is only in a very few forms among those whose anatomy is well known that they are absent. They seem to be entirely unrepresented in the following :— Criodrilus lacuun. “Lumbricus eiseni. Perichaeta acystis. Allolobophora constricta. Geoscolex maximus. Allolobophora samarigera. Anteus gigas. Bothrioneuron vejdovskyanum. Siphonogaster millsoni. Bothrioneuron americanum. All the remaining Oligochaeta (with possibly a few more exceptions) have a varying number of pairs of these organs. Recent researches have brought to light the fact that the sperm-holding organs of the Oligochaeta are of two kinds, morphologically distinct. More generally the spermathecae are sacs which are most probably—though the actual origin has been traced in but few types—derivatives of the epidermis. In the family Eudrilidae these spermathecae are either more or less rudimentary or completely absent, their place being taken by sacs which are derived from the septa of the neighbouring segments and whose cavity is thus THE ANATOMY. SPERMATHECAE 127 coelomic. These two sets of organs of different origin, but of similar function, will be discussed here separately. (1) Spermathecae derived from invaginations of epidermis.—This is the prevalent form of the organ. Spermathecae of this kind are spherical, oval, or more elongated pouches, with or without diverticula, varying in number and position, opening on to the exterior by a more or less pronounced duct and, except in rare cases, ending blindly at the other extremity. Like other organs developed from the epidermis, the spermathecae do not, for the most part, show any ciliation; in rare cases, which, however, may possibly be commoner than is thought, a ciliation does occur; it has been described, for example, in Tubifea; and I have described a ciliation of the spermatheca of Acanthodrilus rosae (48). Cilia seem to be out of place in a sac communicating with the exterior and serving for the storage of sperm. Fig. 32. MICHAELSEN described, some years since, the remarkable fact that in Enchytraeus mébii the IK AS ge SN SEXES li spermathecae instead of ending blindly opened into the gut; he was able to trace the bundles of spermatozoa from the spermathecae into the lumen of the gut by staining methods; he has since SPERMATHECA OF shown that many, indeed most, Enchytraeidae MESENCHYTRAEUS BEUMERI. show the same remarkable connexion between (After Michaelsen.) the interior of the spermathecae and the lumen — 4y. upper extromity is cut off where the of the gut; I can entirely confirm this discovery espe eg the gut, “The two di- for several species belonging to the family Enchy- traeidae; sometimes the aperture is at the tip of the spermatheca, at other times on the side. More recently I have pointed out that in the genus Sutroa there is the same communication between the two organs; and in all probability Rhynchelmis will be proved to agree with Sutroa. On a later page I shall have to direct attention to the fact that in Paradrilus, where the spermathecae are of the second type of these organs, the same thing occurs; it seems, therefore, to be of functional, rather than morphological, importance. Possibly, as has been suggested by MICHAELSEN, this device ensures the getting rid of superfluous spermatozoa, which might otherwise decay and cause injury to the animal by so doing. On the other hand, a second suggestion might be made, which I give for what it may be worth; Wuirman has recently made the very interesting discovery that impregnation among the Hirudinea may take place through the epidermis; the spermatozoa apparently, in some cases, force their way through the body-wall and fertilize the ova lying within 128 OLIGOCHAETA the body; he suggests that the same may be the case with the Oligochaeta, in many of which the spermatophores seem to be attached to the outside of the body ‘anywhere.’ It is just possible that spermatozoa may be conveyed a short distance by the alimentary tract and then make their way out to fertilize the ova. In connexion with the above suggestion it may be noted that Vespovsky could not find in a single case even one spermatozoon in the albumen of the cocoon. The above, however, are rare exceptions to the rule that the spermathecae end blindly in the body-cavity. Among the lower Oligochaeta the organs are generally simple pouches without any diverticula; this is so with the Naidomorpha, the Tubificidae, the Lumbriculidae (except Rhynchelmis and Sutroa), the Phreoryctidae, and the Moniligastridae. Of the aquatic families the Enchytraeidae alone are usually provided with one or more diverticula; the Lumbriculidae are sometimes provided with diverticula—at least Sutroa and Rhynchelmis are. The higher Oligochaeta, as a rule, have diverticula; this is the case with the families Perichaetidae (a few exceptions), the Acanthodrilidae (also a few exceptions), the Cryptodrilidae (like the others with a few exceptions). The members of the two families Lumbricidae and Geoscolicidae never possess diverticula. In the family Eudrilidae there are sometimes spermathecae met with; this statement requires qualification to the extent that spermathecae of the type hitherto considered are sometimes present; the majority of the members of that family have spermathecae of a totally different morphological nature, which are described further on. In those cases where spermathecae derivable from epidermic invaginations (probably, for that fact has not been actually proved) occur, these organs are invariably placed far back in the body, the, most forward position being seen in the genus Heliodrilus, where they are in the tenth segment; the spermathecae are always unpaired and of course open in the median ventral line. They never possess diverticula, and, indeed, appear to be of limited functional importance, as they have not been observed to contain sperm; in Heliodrilus, however, the spermatheca is of great length, extending from its external aperture on the tenth segment as far back as the fifteenth. When diverticula are present, they are of varying degrees of importance; they also vary in number; in the Perichaetidae there is, as a rule, only one diverticulum, which is often of considerable size; two diverticula are found in various Acantho- drilidae and Cryptodrilidae; in Octochaetus multiporus there is a circle of small diverticula round the external aperture of the spermatheca. There are two facts of interest to be noted in connexion with the diverticula; in the first place they are of slightly different structure from the pouch of which they are appendages ; secondly, THE ANATOMY. SPERMATHECAE 129 they contain, in mature worms, spermatozoa, absent in the pouches themselves (see accompanying woodcut, fig. 34). Acanthodrilus dissimilis may be used to illustrate the first point; in this species there are two diverticula to each spermatheca; they are lined with an epithelium which is largely converted into irregular masses of an amorphous appearance, in which are imbedded bundles of spermatozoa; it looks very much as if the lining epithelium had become converted into a substance, the function of which was to hold firmly the spermatozoa until they were transferred to another individual. In other worms the diverticula are lined with Fig. 34. a low quadrangular epithelium differing so far from the tall columnar cells which line the pouch; this is the case with Perichaeta and other genera. In no case have I observed an absolute similarity between the epithelium of the pouch and of the diverticulum: in no ease have I found any spermatozoa in the pouch itself; they were always in the diverticula. Rosa has indicated an exception to this; no doubt it may easily happen accidentally that the sperm goes astray and finds its way into the wrong cavity; the very fact that Rosa thought it worth while to mention the exception shows how widely prevalent is the rule. It is very curious that the spermatozoa should choose the narrow path leading to the interior of the spermathecal appendix rather than the broad and, one would have thought, easier road into the spermathecal pouch. It has been suggested by Brenyam that when the male apparatus is everted in copulation (this can at any rate take place in some worms) ,ongrruDINAL SECTION and pushed into the spermatheca, the everted portion blocks oF THE SPERMATHECA the route to the spermatheca, but leaves free the aperture OF A BENHAMIA. of the sperm-duct which is directed into the appendix. ee ne The question of the function of the various parts of the mA ee spermathecal apparatus will be discussed later (see below). Apart from the presence or absence of diverticula, the number and position of the spermathecae vary in different families of the Oligochaeta. They are sometimes further forward, and sometimes more posterior in situation. The most anterior position in which they occur is seen in the genus Aeolosoma; here the first pair of spermathecae may be as far forward as segment iii. In the Lumbriculidae and in some Geoscolicidae they are as far back as they are ever found—viz. in segments xiv—xvi. 130 OLIGOCHAETA The following table shows all the different segments which may be occupied by the spermathecae in the Oligochaeta :— Segment iil. é : : Aeolosom«. Segment iv. ‘ : : Aecolosoma. Segment vs. : ‘ , Perichaeta. Segment vi. : ; ‘ Perichaeta. Segment vii. P ; : Perichaeta. Segment viii . ; x Perichaeta. Segment ix. ‘ : 5 Perichaeta. Segment x. , : . Allolobophora. Segment xi. : ; ‘ Allolobophora. Segment xii ‘ : : Allolobophora. Segment xiii . : s : Microchaeta. Segment xiv . ‘ : ‘ Microchaeta. Segment xv. 5 : : Kynotus. Segment xvi . ‘ : ‘ Microchaeta. As a rule there is a certain relation between the position of these organs and that of the testes. Thus in Aeolosoma, where the testes are in the fifth segment, the spermathecae commence in the third; in the Naidomorpha they lie in the same segment as the testes, viz. the fifth; this is also the case with the Tubificidae; both testes and spermathecae are in the tenth. In earthworms the spermathecae generally lie in front of the testes; but in the Lumbricidae they are often in the same segments. No very definite relation between the position of the spermathecae and that of any other organ can be traced; any attempt to trace such a relation is rendered difficult by numerous exceptions. It is only in certain Lumbriculidae and in Phreodrilus that the spermathecae are behind all the reproductive organs. They appear never to be placed behind the clitellum. As a rule each segment of those which contain them has only one pair of sperma- thecae; among the Geoscolicidae, however, a very large number of spermathecae sometimes occur in a single segment; thus in Kynotus madagascariensis there are as many as fourteen pairs in one segment. Perichaeta sangirensis, and a few allied species, Allolobophora savignyi, are the only worms not belonging to the family Geoscolicidae in which numerous spermathecae take the place of the more usual pair. This great increase in numbers is accompanied by a reduction in size, more marked in the Geoscolicidae than in the Perichaeta. When the spermathecae are paired, the number of pairs varies from one to seven. One is the usual number in the lower forms, and is THE ANATOMY. SPERMATHECAE 131 perhaps an indication of the simplification of these genera; we find only a single pair of spermathecae in the Tubificidae, the Enchytracidae (with just one exception), the Naidomorpha, most of the Lumbriculidae; Aecolosoma, the lowest of all the Oligochaeta, may have as many as three pairs in segments iii, iv, v. Among the higher Oligochaeta the largest number of pairs, seven, occurs in Allolobophora complanata ; a few Perichaetidae have five pairs, but on the whole two pairs is the prevailing number among earthworms ; the numerous exceptions prevent a comparison between this fact and the existence of two pairs of testes and sperm-ducts; however, when a given species has two pairs of spermathecae and two pairs of male-ducts, and when a disappearance of one pair of the one set of organs in an allied form is accompanied by the disappearance of one pair in the other set of organs, there would seem to be some relation between the two cases; this has happened in Acanthodrilus monocystis; the worm is closely allied to Acanthodrilus dissimilis (see below), in which there is always a double set of spermathecae and male-ducts; in the former species one pair of each has vanished. Very rarely are the spermathecae median and unpaired; this state of affairs exists in the Cryptodrilids grouped together by MICHAELSEN into the genus Jetcherodrilus, in a few Eudrilids (e.g. Heliodrilus), and in the genus Sutroa; also apparently in the Tubificid Vermzculus. The fusion in the middle line of, we must suppose, originally separate and paired pouches is correlated with a similar fusion of the terminal apparatus of the male-ducts. _ There seems to be no doubt, after the investigations of Veypovsky upon Tubifex, and of BercH upon Luwmbricus, that the spermathecae arise as ingrowths of the epidermis; as to the appendices of the spermathecae, where they exist, it is not so certain; in Perichaeta it is common to find the appendix of large size, when the pouch itself is exceedingly small; this looks as if the appendix were phylogenetically older than the pouch, and, if so, the term appendix should be dropped or applied to the pouch itself. I failed to find in immature examples of an Acanthodrilus (A. falelandicus) any connexion between the appendix and the pouch; this almost suggests a different origin for the two. In the neighbourhood of the spermathecae, or appended to them, there are in a few Oligochaeta, peculiarly modified setae, often accompanied by glands. They often bear the same kind of relation to the spermathecae that the spermiducal glands, with their penial setae, do to the sperm-ducts. Physiologically speaking, it is possible that the correspondence is even closer. Among earthworms these’ structures have been described in the Acanthodrilids : in Acanthodrilus wngulatus, A. schmardae, and in Benhamia beddardi in their complete form. In the former species the ventral setae of the eighth segment are 8 2 132 OLIGOCHAETA replaced by long ornamented setae, agreeing very closely in appearance with the penial setae (on the seventeenth and nineteenth segments) of the same worm. These setae are enclosed in a thin, muscular sac, on either side of which is ‘a long some- what sausage-shaped glandular body, which communicates by a slender duct with the orifice through which the setae project on to the exterior. The minute structure of these glands is unfortunately unknown. Among the aquatic Oligochaeta the only species with any appendages comparable to the above is Psammoryctes barbatus. In this Tubificid there is a sac (see fig. 35) containing a single penial seta opening either into the spermatheca, just at its external orifice, or independently, but close to it. Two glandular sacs pour their secretion out on to the external surface by the same pore. Of the origin of the spermathecae it is difficult to offer any hypothesis that is convincing. BrrcH regards them as quite new structures developed for the purpose that they have to perform; it seems to be not proved that they have any connexion with the nephridia (see above). The oceasional close relations in the way of position which the spermathecae have to some of the genital ducts, suggests a possible origin for them as diverticula of such ducts. In the genus Phreo- SPERMATHECA OF PSAMMORYCTES BARBATUS. (After Stolc.) drilus I have described a long coiled diverticulum of the sperm-duct, which shows, at any rate, that such diverticula can exist ; 1 have suggested that A. The entire spermatheca. B. The distal ‘ “ # extremity more highly magnified. .. Genital the meaning of this diverticulum may be that a ee of glands ‘4. it is a rudimentary second sperm-duct. In the Eudrilid Alvania the oviduct has a similar though smaller diverticulum ; if these diverticula became separated from the ducts of which they are outgrowths, and acquired an independent opening on to the exterior, they would be of the same character as the spermathecae. Beyond these scanty facts, however, there is no evidence of such an origin of the spermathecae, probable enough though it is on a@ priori grounds. In Hudrilus, of course, the spermatheca is a diverticulum of the oviduct, but this instance can hardly be made use of THE ANATOMY. SPERMATHECAE 133 since the spermatheca of that worm is morphologically a different thing from the spermatheca of those types that have just been mentioned. There are some facts which tend to prove that the spermathecae are, like the spermiducal glands (see above), derived from copulatory glands; the facts, however, are not so conclusive in this case as they are (in my opinion) in the other case. It must be noted, in the first place, that copulatory glands with modified setae occur in the neighbourhood of the spermathecae. They have just been mentioned. There are therefore no reasons against such an origin as there might perhaps be were the glands in question never present in the anterior region of the body, but always confined to the neighbourhood of the male-pores. Whether the glands in the anterior region of the body are exactly similar to those in the posterior region is not certain; some facts tend to show that they are. In Rhynchelnis, for example (VETDOVsKY 5), the albumen-gland is lined by two layers of cells, and recalls in this particular the spermiducal gland of the same species. The great similarity, too, between the setae which accompany the glands in Acanthodrilus wngulatus to the penial setae of the same species are facts which point in the same direction. The spermathecae are lined with a single layer of epidermis, and appear at first to differ very greatly from the glandular bodies with which it is sought to compare them. It must be borne in mind, however, that in certain Oligochaeta—in many Enchytraeidae—a smaller or greater part of the spermatheca is covered with a glandular layer, which seems to me to be strictly comparable to the glandular investment of the spermiducal gland. Even in the higher Oligochaeta this condition is not altogether unknown. Perichaeta houlleti is characterized by the fact that there is appended to the spermathecae a pear-shaped body, described by PERRIER as a diverticulum, but shown by myself to be simply a mass of pear-shaped glandular cells. The relations of this to the spermatheca are very similar to those of the ‘Cementdriise’ to the ‘atrium’ in Tubifex'. There are two other points in which the spermathecae seem to show a resemblance to the spermiducal glands, and therefore to the copulatory glands, from which it is assumed that the latter have arisen by a slight modification. In Psammoryctes the long spermatheca has a diverticulum which lodges a penial seta. Its relations to the spermatheca are exactly similar to those which exist between the copulatory glands and their modified setae. The other resemblance is rather with the spermiducal glands, but it obviously amounts to much the same. In Moniligaster bahamensis (BepparD 57) and in Moniligaster indicus (BenHam 16) the spermathecae do not, as is ordinarily the case, open directly on to the exterior of the body; their ' Cf also the cap of glandular cells figured by me (28) in the spermatheca of Diachaeta littorulis. 134 OLIGOCHAETA duct opens on to a papilla, which itself projects into the interior of a terminal sac. This is, of course, highly suggestive of the penis in the Tubificidae and in some others. I figured, but did not describe, this structure in my paper quoted above. On this hypothesis we have, of course, to account for the spermathecal diverticula, whose presence is so marked a feature of the Megascolicidae. An obvious suggestion is that they are the sacs which formerly gave rise to the copulatory setae. 2. Spermathecae formed from mesoblustic structures——The Eudrilidae are charac- terized by the possession of spermathecae of a different kind to those that have been hitherto considered. In a few genera, as already described, there are sperma- thecae of the ordinary kind, only differing from those of the majority of the Oligochaeta in being situated posteriorly. In most genera, however, the place of these organs is taken by sacs which are developed from the septa, and whose cavity is therefore coelomic. I describe the variations of these more particularly under the family Eudrilidae, inasmuch as they are peculiar to that family and appear to have no relation to any other organs found among other earthworms. These sacs are generally large and generally unpaired, paired only in Hudrilus, Pareudrilus, and Nemertodrilus; if true spermathecae are present, these sacs involve them; if such spermathecae are not present, they open on their own account on to the exterior. Often they communicate with the sac that in the Eudrilidae generally envelops the ovaries, and they contain therefore both sperm and ova. That there should be organs performing the same function, but morphologically quite distinct, in a group which is so comparatively limited as that of the Oligochaeta, is perhaps the most remarkable fact in the economy of that group, and is not paralleled by any other structure. 5 I will take as an example of these structures the spermathecal sac of Libyodrilus (PL. iv. fig. 1). When the worm is dissected, a large sac, extending through several segments (xiii-xviii), is seen to lie dorsally covering the gut. It is of a brownish- yellow colour, and is of an irregular elongated form, with numerous furrows on the surface which appear to indicate the possibility of distension. It has three pairs of diverticula reaching for some way down the sides of the gut. From the anterior of these arise the oviducts, one on each side. Anteriorly the sac bifurcates, embracing the oesophagus and reuniting below it. It then again divides so as to surround the nerve cord; the two branches reunite below the nerve cord before opening by the single median pore on to the exterior on segment xiii. The oviduct does. not, as it appears to do, open into this spermathecal sac. A small roundish projection marks its attachment to the sac; this round body is the egg-sac, and has the structure characteristic of that organ in other Oligochaeta. Its lumen does not communicate THE ANATOMY. SPERMATOPHORES 135 with the lumen of the spermathecal sac except indirectly. This communication is brought about by the oviduct, the funnel of which is drawn out into two tubes, one opening into the egg-sac, the other into the spermathecal one. In transverse sections the anterior wall of the spermathecal one is seen to be formed by the septum dividing segments xiii/xiv. The microscopic structure of the sac is as follows: it is a thickish muscular coat, the fibres of which run in various directions ; imbedded in this muscular coat is a structureless sheet, which has sharp edges and is highly refractive; it is undoubtedly a membrane, and is probably elastic in nature, allowing for the distension of the sac with sperm, and its subsequent shrinkage when the sperm is evacuated. The sac is lined with cells of an irregular, somewhat elongated form, occasionally forming several pores; these cells contain numerous granules and are very similar to peritoneal cells. in other parts of the body. I have been able to trace the development of this sac through several stages. In the youngest stage I found a sac below the nerve-cord freely opening into the body-cavity ; the walls of this sac were formed by the intersegmental septum xiii/xiv in front, and behind by a sheet of membrane, which traced backwards was seen to connect that septum with septum xiv/xv. The pouch was formed by the attachment of this membrane to the body-wall as well as to the septa, and was, therefore, freely open at both sides. The ovary was attached to this membrane, just where it joined septum xiii/xiv. In a later stage there was a more completely closed sac lying beneath the nerve-cord, extending for a short distance into the thickness of the body-wall; above this sac, divided to embrace the nerve-ccrd and dorsally to the nerve-cord, opened freely into the body-cavity; here its walls were obviously formed in front by septum xiii/xiv, and behind by the other membrane already referred to. The ovary lay between the two membranes. On the ventral surface of the body, just below the pouch, the epidermis had no gland-cells; whether it is ultimately invaginated to form the orifice of the spermathecal sac, or whether the sac bores its way to the exterior I am unable to say; but in any case the cavity of the sac evidently begins as a coelomic space. § 11. Spermatophores. A considerable number of Oligochaeta form cases for the enclosure of packets of spermatozoa, which have been usually termed spermatophores. These were first discovered in the Lumbricidae, and from their being attached to the exterior of the body in the neighbourhood of the clitellum were regarded at one time as penes. Spermatophores, although met with in a good many Oligochaeta, are apparently by 136 OLIGOCHAETA no means universal in the group; neither do they occur in every genus belonging to those families in which they have been met with. At present they are known to exist in the following families only :— Naidomorpha? Geoscolicidae (Criodrilus). Tubificidae. Eudrilidae (Polytoreutus). Lumbricidae. Eclipidrilidae. In the Naidomorpha LANKrsterR (9) has described spermatophores in Nazis serpentina. They are figured by him as long-coiled aggregations of spermatozoa more or less similar to the immature spermatophores of the Tubificidae, but entirely lacking the complicated structure which these bodies show when fully ripe. VeJDovsKY (24, p. 153) could not, on the other hand, find any definite spermatophores in the Naidomorpha. Among the Tubificidae the spermatophores have been known for a long time. They were figured by Ducks (1, Pl. VII, tigs. 2, 4) in Tubifex (‘Nais filiformis’), and termed in the description of the plate ‘animalcule spermatique.’ In the text it is suggested that they are too large to be probably so designated. Buna, though noticing the same structures, made no suggestion as to their nature. LANKESTER has given a more detailed account of the spermatophore of Tubijea rivulorum in a subsequent paper (2), which is copiously illustrated. The sperma- tophore has a long, worm-like form, and generally a conical head with a collar just below; its peculiar form is due to the fact that it is moulded in the interior of the spermatheca. The spermatophore is composed of a cementing matrix in which are imbedded the spermatozoa; when fully formed Jt has rather a complicated structure. Centrally there is an axial band, apparently a canal, but filled with granular matter and darkly stained by carmine. External to this is a narrowish, highly- refringent band, and following this a broad band in which are imbedded the spermatozoa ; these are imbedded parallel to each other and run obliquely ; externally to this is another highly refringent layer, and beyond this project the ends of the spermatozoa, which are in constant vibratile motion. When the spermatophore is examined in transverse section, the spermatozoa are seen to have an imbricated arrangement which suggests that they have been fitted together by a twisting motion. Lsammoryctes has a spermatophore of a rather different form. Its most marked peculiarity is a series of recurved hooklets at one extremity; these are figured by Vespovsky (18, Taf. viii, figs. 11, 12), but not by LANKESTER (2), who has also described the spermatophore of this worm. Otherwise the structure of the spermato- THE ANATOMY. SPERMATOPHORES 137 phore appears to be much as in Tuhbifex. But the conical head ig absent as it sometimes is in Tubifea. In Tubijfex blanchardi, lately discovered by VuspovsKy (8), the ripe spermatophores have a distinct aperture at the anterior end, which, though apparently not always (see figs. 7, 9 of VEspovsky’s paper), communicate with the central canal. The free ends of the imbedded spermatozoa form, as in Limnodrilus, a spiral upon the outer surface of the spermatophore, A very remarkable kind of spermatophores oceur in Bothrionewron, where they have been described and figured by Stoic (3); as, however, his description is in the Bohemian language I have only been able to use the facts so far as they have been translated by Vespovsxy (8). These are invariably met with clustered round the male-pore, where they are attached to the skin. The genus is exceptional among the Tubificidae in possessing no spermathecae ; which organs in other Tubificids always contain the spermatophores. Their shape is unlike that of the spermatophores in the other genera and is more like that of the Lumbricidae. They consist of a narrow stalk and of a more swollen distal portion which contains the spermatozoa. In the Tubificidae the spermatophores appear to be derived from two sources; the granular axis is the product of. the secretion of the ‘Cement gland, while the rest of it is produced by the epithelium of the sperma- thecae. This is the conclusion of LAnKESTER (2) and Vrspovsky! (24); but it must be admitted that the origin is not yet definitely established. In Bothrioneuron there are no spermathecae, and the structure termed by VesDovsky paratrium must be the place where the case is formed. The different character of the spermatophores of this Tubificid correspond to the different place of their formation. Among the Lumbricidae spermatophores constantly occur. The most detailed account of these structures is to be found in Fratssn’s paper upon the subject. They are small chitinous sacs, of an elongated, rounded form, with a more or less distinct stalk. The dilated end is filled with sperm, and FrRatssz figures an aperture through which the sperm can escape, when the proper time arrives. There are trifling differences in form; the spermatophores vary in shape according to the species of worm. The origin—that is to say the place of formation—of these structures has been disputed; FRaisse traces them to glands in the neighbourhood of the setae, on the first clitellar segments, which are the tubercula pubertatis. He figures, however, branching tubes in the thickness of the clitellar epithelium, composed of a single layer of columnar cells surrounding a lumen. VEJDOVSKY was 1 The ‘moulding’ of the head of the spermatophore to the shape of the distal end of the spermathecae in Tubifex rivulorum is, of course, a strong argument. T 138 OLIGOCHAETA unable to find these, and their presence, with the function attached to them by FRAISsE, seems to me to be unlikely. It is possible that the tubes in question are the nephridial ducts, which we know, from Husrecut’s researches (see above), often open on to the exterior at some distance from that point where they first perforate the body-wall. A main objection to the formation of the spermatophores by the tubercula pubertatis is, according to Vespovsky, their frequent occurrence at points somewhat remote from these tubercula. He (Vespovsky) regards the spermathecae as the site of their formation. It is not, however, necessary to go into this suggestion at length, since spermatophores exist in Criodrilus, where there are neither spermathecae nor tubercula pubertatis. Rosa (4) has, therefore, suggested that the glandular protuberance on to which the sperm-ducts open in so many Lumbricidae is responsible for the secretion of the ease of the spermatophore. This suggestion is decidedly in accord with the facts. It explains, for example, the large size of the spermatophores in Criodrilus, where the glands in question are largely developed, as well as the fact that they have not been discovered, in spite of diligent search, in Allolobophora complanata, where the swelling at the termination of the sperm-duct is wanting. The suggestion also, according to Rosa, explains the position of the spermatophores; for they are found ‘always on the segments which during copulation are placed in front of the male- pores. In Allolobophora samarigera the spermatophores are, most exceptionally, found dorsally on the fifteenth or sixteenth segments. The pear-shaped spermatophore thins out on all sides into a thin and leaf-like lamella, reminding one in fact of » a pine seed. Among exotic earthworms spermatophores have only been discovered (by myself 89) in the Eudrilidae, and within that family only in the genus Polytoreutus. They have been found in more than one species of the genus, and are in all probability characteristic of it. The spermatophores of Polytoreutus are not at all like those of the Lumbricidae or of Criodrilus, and in fact are peculiar to the genus which they characterize, though somewhat like the immature spermatophores of Tubifea. They are very long, and commonly thicker at one end. They consist of a tolerably thick, transparent axis, to which the spermatozoa are attached, and within which they are but slightly imbedded. Finally, the spermatophores of Eclipidrilus may be briefly described. These are stated by Ersex (8) to be glassy transparent bodies; they are sculptured externally with a raised spiral line; the upper extremity of the spermatophore is dilated and spherical. THE ANATOMY. CLITELLUM 139 $ 12. Clitellum. It is almost, if not quite, certain that the clitellum exists at the period of sexual maturity in all Oligochaeta. Doubtless a good many forms exist which have not been proved to possess a clitellum, and the absence of this organ has been frequently used by some of the earlier writers as a mark of specific distinction; but many of these cases have been shown to have been inaccurately described—a clitellum being really present in the fully mature worm. The quite recent discovery of the clitellum in the families Aphaneura and Moniligastridae has eliminated any doubt as to the presence of a clitellum in the only families in which it had hitherto eluded discovery. The Moniligastridae, indeed, were placed by Perrier in a separate group, that of the ‘Aclitellians,’ supposed to be distinguished by the absence of this highly characteristic organ. The failure to find it in that group was probably due to its temporary presence, or to its not by any means strongly marked appearance. There is one genus of Oligochaeta, however, from which the clitellum may conceivably be really absent, or rather represented by a somewhat different structure. This genus is Siphonogaster. The male-pores of Siphonogaster open near to the extremity of long penial processes, which have been referred to on a previous page. The epidermis of these processes has quite the structure of the epidermis of the clitellum, and, in fully mature worms no trace of a clitellum occupying the normal position could be found. Unfortunately, as is the case with practically all the exotic earthworms, we have no such knowledge of the habits of the ‘Yoruba worm’ as would give a clue to the use of these long ‘penial’ processes. It is possible that their’s may be the function of a clitellum. With this possible exception, then, the clitellum appears to be present in all Oligochaeta—in the aquatic no less than in the terrestrial forms. Its presence indicates, with more or less accuracy, the breeding period; its function is that of producing the cocoon and when that function has ceased the clitellum disappears. The period of existence, however, seems to vary very much in different Oligochaeta. The aquatic Oligochaeta without exception, and probably the Moniligastridae also, have a fixed and definite breeding-time, during which alone the clitellum is developed. This period differs according to the species; in the case of some the autumn, in the case of others the winter, is the time of sexual activity; this restriction of the breeding period accounts for the fact that in so many of the aquatic Oligochaeta the clitellum is unknown. Other influences, too, in addition to the season of the year, are doubtless at work in retarding or accelerating sexual Te 140 OLIGOCHAETA maturity and, in consequence, the development of the clitellum. I kept under continual observation a quantity of Ilurida, Timm. (3) +» lacustris, LInné. (8) ,, josinae, VEJDOVSKY. (4) 5, serpentina, MULLER. v (9) » heterochaeta, BENHAM. (5) » gracilis, LEIDY. j (10) 4, reckei, FLOERICKE. In addition to these there are a number of worms which are very possibly members of this genus, but of which no sufficient descriptions exist. These species may be first considered. The Nais fusca of CaRTER (Ann. and Mag. Nat. Hist. (3), ii. p. 20), from its habitat might be supposed to be distinct had it not been shown that these smaller Oligochaeta have often a wide range. Its chief difference from Nais elinguis is, as VAILLANT has indicated, the absence of eyes; pending further information it may there be regarded as doubtfully distinct. A number of other species have been provisionally referred to this genus by VAILLANT; some of these, however, are clearly not referable to the genus, while others are insufficiently characterized to permit of their generic position to be stated with any approach to accuracy. They will be found cited on other pages. DESCRIPTIONS OF GENERA AND SPECIES 283 I am inclined to think that FLopRIcKE’s genus Caecaria will have to be incorporated with Nais. He regards it as intermediate between Stylaria and Pristina, It has no eyes, a long prostomium, and the dorsal setae begin on the sixth segment. In Caecaria rara the second, third, and fourth dorsal bundles are much shorter than the others. In C. silesiaca only the first bundle is shorter. In C. brevirostris all are equal. Pending further information, I leave the species as incertae sedis. N. clavicornis of Sars (Beskrivelser og iagttagelser, &c., Bergen, 1835), is apparently a Tomopteris. N. bipunctata (DELLE CHIAJE), N. picta (DUJARDIN), N. quadricuspidata (FABRICIUS) are also Polychaeta. N. carolina (BLANCHARD) is quite unrecognizable. N. scotica is referred to below. (1) Nais barbata, O. F. Mourn. ? N. barbata, O. F. MULuer, Verm. terrestr., 1774, vol. i, pt. ii, p. 23. 1 Opsonais obtusa, GERVAIS, Bull. Ac. Roy. Belg., 1838, p. 17. N. elinguis, DirrrenBacu, Anat. u. Syst. Studien, 1885, p. 98 (in part.). Definition. Dorsal setae bundles with capilliform setae only, which are of two sizes, four to eight in each bundle. Eyes present. The brief diagnosis of this species given by O. F. MULLER would not be enough to identify even the genus to which the worm belongs, did he not refer to his account of the bearded Naid (die bartige Naide) published with a plate in an earlier work (2). The drawings referred to indicate a Nais or a Bohemilla, more probably the former, since the much smaller eyes of the latter genus would perhaps have escaped MULLER’s attention. There is, however, nothing in the figure to enable one to determine with certainty the identity of this ‘birtige Naide’ with the species subsequently called Nais barbata by TAUBER, VEJDOVSKY, and others. The only distinction between the ‘bearded Naid’ and the ‘tongueless Naid’ mentioned by MULLER is the ‘beard’ of the former, which is evidently the ventral setae of the four first setigerous segments closely crowded together’, for MULLER says (2, p. 81) ‘unter dem Kopf erscheint ein Klumpen kurzer Borsten gleich einem Barte, and is, therefore, not a distinction. Strictly speaking, the name ‘barbata’ ought perhaps to be dropped, and replaced by Gurvars’ ‘obtusa,’ but as the former name is now so well established, such a change is inadvisable. This species has been greatly confused with the nearly allied VO. elinguis. D'UDEKEM distinguished them only by the presence or absence of the glandular ventricle. This, however, is no difference; the structure in question appears to be present in both ?. TauBeR (p. 73) first indicated the only real difference between the two species 1 Drerrenpacu (p. 104) evidently did not so interpret the structure in question when he wrote ‘eine Nais barbata ... mit besonderen kleinen Haaren am Munde, habe ich nie finden kénnen.’ Vartiant’s figure (6, Pl. xxii. fig. 14), by exaggerating the tactile hairs of the prostomium, might lead to the inference that these were the ‘ beard.’ 2 Vuspovsky, at least, does not refer to its absence in 0. barbaia; but Dirrrenzacu says it is occasionally absent in his N. elinguis (= 0. elinguis + 0. barbata). 002 284 OLIGOCHAETA which concerns the seta, and is mentioned in the diagnosis of the two worms given here. Another difference referred to by TAUBER is that in O. barbatu the ova are deposited in October and November’. As TavuBER pointed out, SEMPER also confused these two species. So, too, DIEFFENBACH (p. 99) who regarded the individuals with bifurcate setae in the dorsal bundles as a variety of WV. elinguis. The species is figured by MULLER, VaILLanT (6, Pl. xxii, figs. 14, 15). FLOoERICKE has applied the name of NV. greeffi to a worm which I regard as a variety of the present species ; the ventral setae are, as in MV. elinguis, of equal length throughout the body; whereas in NV. barbata those upon the first four segments are longer. (2) Nais elinguis, O. F. Mixuzr. SUN. elinguis, O. F. MULLER, Verm. terrestr. vol. i, pt. ii, 1774, p. 22. Opsonais elinguis, Gervais, Bull. Ac. Roy. Belg., 1838, p. 17. N. rivulosa, Lerpy, Journ. Acad. Nat. Sci. Philad., 1850, p. 43. Definition. Dorsal seta bundles with capilliform and hastiform setae, one to three in each bundle. Eyes present. Hab.—LEurope; N. America. I think that Lerpy’s WV. rivulosa cannot be differentiated from N. elinguis. This is also the opinion of VaInuanT (6, p. 371) and p’UDEKEM (5, p. 20). VAILLANT, however, suggests as a possible difference the greater slenderness of the ventral setae in the American species. (3) Nais lacustris (Linnazvs). Nereis lacustris, Linnaxzus, Syst. Nat., 1767, p. 1085. Nais proboscidea, O. F. MULuer, Verm. terrestr. vol. i, pt. ii, 1774, p. 21. Stylaria proboscidea, EHRENBERG und Hempricu, Symb. Phys., 1831. Stylaria paludosa, Lamarck, Hist. An. sans Vert., 1816, iii, p- 224. . Stylinais proboscidea, Grrvats, Bull. Ac. Roy. Belg., 1838, p. 18. \\Stylaria lacustris, JOHNSTON, Cat. Worms, 1865, p. 70. ? Stylaria phyladelphiana, CZERNIAVSKY, Bull. Soc. Nat. Mosc., 1880, Pp. 309. ? Stylaria fossularis, Lerpy, P. Acad. Nat. Sci. Philadelphia, 1852, p. 287. non-N. lacustris, DALYELL, Powers of the Creator, ii, 1853, p. 130%, Definition. Length, 15 m.; number of segments, 25. Prostomium much elongated. Dorsal seta bundles with capilliform setae only. yes present. Hab.— Europe and America. ' As Vespovsky (24, p. 29) has pointed out, the ova of 0. elinguis, though usually laid in June, are sometimes deposited in autumn, so that this difference is not absolute. 2 Chaetogaster. DESCRIPTIONS OF GENERA AND SPECIES 285 This species is referred by recent systematists (VrsDovsKy, Bourne, and others) to a distinct genus. I prefer to follow p’UpEKEM and LevinseNn in regarding it as congeneric with NV. elinguis, &c. If any species of this genus is to be removed from the others, it should be O. yostnae. The only character upon which a generic definition could be based is the long prostomium. Were we acquainted with a considerable number of species showing this character, it might be advisable to give it generic value. In the meantime, as there is only one species certainly known, it seems more consistent to lay stress upon the similarity in the cephalization with other species. This Annelid is one of the best known. It has been studied by Bonnet, TREMBLEY, MULLER, GRUITHUISEN, TAUBER (2, 3), VEJDOVSKY (24), and others. : There is absolutely nothing in the very imperfect description given by Lerpy of his two species ‘Stylaria paludosa,’ and ‘Stylaria fossularis’ ta enable one to understand on what grounds they are separated from ‘ Stylaria lacustris.’ The worm measures 10-15 mm. in length; the prostomium is long and slender: its length is put down by MULLER as equal to ten segments of the body. The setae of the dorsal bundles (two or three to each bundle) are long and capilliform; the ventral setae (four to six per bundle) are sigmoid and cleft at the extremity ; there is sometimes a median swelling, Bourne ‘occasionally observed specimens in which dorsal setae were present in the one or two most posteriorly placed of the usually cephalized segments.’ The species is illustrated by BLAINVILLE (Pl. xxiv, fig. 3), Cuvimr (Pl xxi, figs. 2, 2a), DALYELL (Pl. xvii, figs. 6, 7), D’UDEKEM (4, PI. iii, figs. 17-21), VEJDOVSKY (24, Pl. iii, fig. 27, Pl. iv, figs. 1-24, 26-31). (4) Nais serpentina, O. F. MULuer. _N. serpentina, O. F, Miuuer, Verm. terrestr., vol. i, pt. ii, 1774, p. 20. A Ophidonais serpentina, Grrvais, Bull. Ac. Roy. Belg. 1838, p. 19. ‘Serpentina quadristriata, OrrsTED, Nat. Tidsskr. 1842, p. 134. ? Ophidonais vermicularis, GERVAIS, Bull. Ac. Roy. Belg. 1838, p. 19. Slavina serpentina, BousFrIELD, J. Linn. Soc. 1886, p. 268. Definition. Dorsal setae short, straight, and bifurcate. Ventral setae of first four bundles with a median thickening; on setae of posterior segments the swelling nearer the fixed end. Three or four pigmented bands on segments II-V. Hab.—Lurope. This species, described by ROseL and O. F. Miuuer (2) (by the latter under the name of ‘Die geschlingelte Naide’) in the last century, has been chiefly studied by 286 OLIGOCHAETA LANKESTER and VEJDovsKY. It is the largest of European Naids, measuring, according to the last-named observer, 1-5 to 2 centimetres in length. A chain of four Zooids measures as much as 3 cm. An illustration showing the natural size of the worm is given by O. F. MULLER (2, Tab. iv, fig. 1). In a magnified representation (2, Tab. iv, fig. 2) the characteristic transverse bands of pigment, which led to OERSTED’S specific name of ‘quadristriata’ are shown. A drawing by D’UDEKEM, reproduced by VAILLANT in the third volume of the ‘Histoire des Annelés’ (Pl. xxiii, fig. 12), shows the same feature, also recognizable in the first published illustration of the worm--that by ROsEL. Ophidonais serpentina is not only larger, but more opaque than other Naids, and is, therefore, less easily studied. It is, therefore, doubtful whether WILLIAMS (1) really investigated this species, since he speaks of ‘the softness and transparence of the integuments,’ The pharynx occupies the first four segments, being somewhat constricted in the middle and dilated at the two extremities. The oesophagus has no glandular swelling but passes (in the ninth segment) into the intestine; the intestine as well as the last three segments of the oesophagus, are covered with brown peritoneal cells. The dorsal blood-vessel communicates with the ventral by three pairs of vascular arches as well as at the anterior extremity, where it divides into two branches which reunite to form the ventral vessel. The two last pairs of arches, belonging to segments iii and iv, are quite simple ; the first pair branch dichotomously, the branches join either one of the two halves of the dorsal vessel or the single ventral trunk. This branching is evidently a simplification of the conditions which occur in WN. josinae (p. 288). This species has been found with fully developed sexual organs in June (LANKESTER), September, and October (VEJDOVSKY). GERVAIS (pp. 19, 20) describes both 0. vermicularis, and O. serpentina, but declares that it is impossible ‘bien caractériser deux especes de ces animawtx’; above GERVAIS remarks upon having taken ‘plusieurs fois des Nais vermicularis ou serpentina, & Paris.’ I presume, therefore, that I am right in adding 0. vermicularis to the list of synonyms. The species is figured by Métuer, Brueuibre (Pl. liii, figs. 1-4 [after Minuer]), VesDovsky (24, PI. iii, figs. 14-16), VAILLANT (6, Pl. xxiii, fig. 12), OERSTED (8, Pl. iii, fig. 3), and BousFIE.D (1, Pl. xxxiii, fig. 5). (5) Nais gracilis, Lerpy. N. gracilis, Lerpy, Journ. Acad. Nat. Sci. Philad. 1850, p. 43. Slavina gracilis, VEJDovsKy, Syst. u. Morph. 1884, p. 30, Definition. Length, 10 mm.; number of segments, 50; dorsal setae capulliform only ; those of 1 “Nais vermicularis auctorum,’ GERVAIS. DESCRIPTIONS OF GENERA AND SPECIES 287 segment VI longer than the rest ; dorsal bundles of this segment contain three setae each ; im the following segments only one dorsal seta on each side. No glandular ventricle. Eyes present. Hab.—Neighbourhood of Philadelphia. This species evidently belongs, by virtue of the specially elongated setae of the sixth segment, to VEJDOVSKY’s genus Slavina, which, as it appears to me, VAILLANT was right in joining with ‘Nats’ (=Opsonais). ‘N. gracilis, however, is probably not identical with V. appendiculata, for LErIDY makes no mention of the sensory papillae which, if present, would hardly have escaped his attention. Furthermore, it seems to differ in the limitation of the number of the dorsal setae, and in the absence of a glandular ventricle. (6) Nais appendiculata, p’UpEKem. N. appendiculata, D'UpDEKEM, Bull. Acad. Roy. Belg. t. xxii, pt. ii, 1855, , BP 552. \~ Slavina appendiculata, VEJDOVsky, SB. Bohm. Ges. 1883, p. 219. ? N. escherosa, GRUITHUISEN, Nova Act. Ac. Nat. cur. 1828, p. 409. Definition. Dorsal setae capilliform only, those of siath segment very much longer than those of other segments. A row of sensory papillae upon all the segments of the body. Hab.— Europe. There can be no doubt that Slavina appendiculata of VEJDOVSEKY is the same species as VV. appendiculata of D’'UpEKEM. The characteristic sensory papillae are referred to by D'UDEKEM as ‘appendices couverts de spicules, and figured (fig. 3 of his Plate illustrating Memoir), It has been also thought to be identical with the NV. lurida of Timm, with which, however, it cannot be confounded. The worm is figured, in addition to the above quoted authorities by VEsDovsky (24, Pl. iii, fig. 17-26), BousrreLD 1 (Pl. xxxiii, figs. 2, 3, 4, copies from Vuspovsky and D’UDEKEM). (7) Nais lurida, Tm. N. lurida, Tru, Arb. Zool. Zoot. Wiirzb. 1883, p. 153. Slavina lurida, BousFIE LD, J. Linn. Soc. 1886, p. 268. Definition. Number of segments, 40; first pair of dorsal setae very long ; not more than two in each bundle. Two rows of integumental sense bodies on each segment, Hab,—Europe. BousF1ELD has re-examined this species, and shown it to be quite distinct from 288 OLIGOCHAETA N. appendiculata, with which it has been confounded by Var~Lant. A ventral view of the anterior segments is given by BousFIELD. (8) Nais josinae, VEJDovsxy. N, josinae, VesDovsKy, SB. Bohm. Ges. 1883, p. 218. Definition. Length, 8 mm. Dorsal setae bundles, consisting of both capilliform and uncinate setae ; ventral setae uncinate only. In anterior segments the dorsal vessel forms a network. Eyes absent. Hab.—Teufelsee, Bohemia. This species has been carefully studied by VEspovsKy (24); it is impossible to say whether it is or is not identical with WV. fusca of Canter and N. scotica of JOHNSTON. The worm is described by VEsJDovsKy as resembling a T'uhifex on account of its size (6-8 mm. in length, 15 mm. when dividing). The setae at once distinguish it from O. elinguis, for the bifurcate setae of the dorsal bundles are sigmoid, and not straight as in that species. The dorsal vessel anteriorly becomes reduced in calibre; it gives off, in the first five segments, five or six pairs of lateral branches, which form an irregular network; in the posterior segments pairs of lateral trunks (one pair to each segment) with the dorsal and ventral trunks. In segments vii, vili, and ix, these vessels are shorter and stouter, and form veritable hearts, comparable to those of the higher Oligochaeta. The organization of the vascular system of this species places it on a higher level than the other members of the genus to which it may be (in my opinion only temporarily) referred. A more complete knowledge of its structure may very possibly necessitate the creation of a new genus for its reception. * (9) Nais heterochaeta, Benuam. N. heterochaeta, Bennam, Q. J. M. S. vol. xxxiv, 1893, p. 383. Definition. Length, 6 mm.; number of segments, 41. Dorsal bundles consisting of one capilliform and one uncinate seta. Ityes present. Vascular trunks uniting dorsal with the ventral vessels of anterior segments connected successively. Hab.—England. This species has a remarkable vascular system, of which the following is a more detailed description. The dorsal vessel divides, as usual, in the prostomium into two lateral trunks, which unite in the fifth segment. The branches running from the dorsal to the lateral trunks in the second segment divide, each of them, into two with a separate union with the laterals. The corresponding circumoesophageal vessels of the next segment give off a branch which joins the perioesophageal of the fourth segment. DESCRIPTIONS OF GENERA AND SPECIES 289 The latter give off a similar branch which, before uniting with the perioesophageal of the fifth segment, is connected twice with the lateral vessel of its side. The perioesophageal vessel of the fifth segment gives off a branch which joins that of the sixth ; the latter bifurcates, and has two separate unions with the ventral vessel. This is an approach to the irregular network of N. josinae. There are slight variations in the setae, sometimes two uncinate or no capilliform in the dorsal bundles, but the above is the normal arrangement. The pigmented covering of the intestine begins in the sixth segment. (10) WNais reckei, FLorricks. Ophidonais reckei, FLOERICKE, Zool. Anz. 1892, p. 469. Definition. orsal setae short, straight, and pointed. Other characters as in N. serpentina. Hab.— Germany. The setae of this species are unlike those of any other Naid. They are straight and cylindrical, and suddenly end in a fine point. Genus PRISTINA, EHRENBERG. Syn. Pristina, EHRENBERG. Pristinais, GERVAIS. Nais, D'UDEKEM (in part.). Stylaria, TAUBER (in part.). Naidium, ScHMIDT. DEFINITION. Dorsal setae commence in the second segment, capillary only or capillary and hastiform, the latter bifurcate or not bifurcate at extremity. Eyes absent. Glandular ventricle present. Septal glands well developed. I venture to differ from all recent authorities, in combining the two genera Pristina and Naidiwm. This step appears to me to be rendered necessary by Bourne’s (5) description of two species which nearly entirely bridge over the gap which formerly separated the two genera. Previous to the publication of that paper the two genera might be thus distinguished. PRISTINA. NarpIum. (1) Dorsal setae of segment iii very long.. (1) These setae not longer than the others. (2) No bifid hastiform setae. in dorsal (2) Such setae present in dorsal bundles. bundles. (3) Prostomium elongate. (3) Prostomium short. YP 290 OLIGOCHAETA The two new species of Bourne—Pristina equiseta and P. breviseta—do away with the first and second differential characters. In view of the identity in the cephalization of the two genera, the remaining points of difference are, perhaps, hardly of sufficient importance to warrant generic separation, particularly as only one species of Naidium is known, and its range of specific variation, therefore, not ascertained. In both Naidiwm and Pristina the restriction of the pharynx to two segments, and the great development of the septal glands are especially remarked upon by VespovsKy, and constitute a bond of union, which may be considered to counterbalance the differences mentioned above. The well-marked species belonging to this genus are only five, viz.: — (1) Pristina longiseta, EHRENB., Europe and N. America. (2) 3 equiseta, Bournez, England. (2) 3 breviseta, BourRNE, Madras. (4) os lutea, O. Scum., Europe. (5) ‘ proboscidea, F. E. B., 8. America. One or two doubtful forms have also been described too incompletely for satisfactory recognition !. Pristina inaequalis of EHRENBERG has been thus defined by him :— ‘Setis quaternis inaequalibus, una longissima, reliquis brevissimis, pari secundo non diverso, uncinis, subquinis subulatis.’ Pristina breviceps (=Naidium breviceps, O. ScHMIDT) is thought by Vrespovsky to be an Enchytraeid. Nais ternaria of SCHMARDA is doubtfully transferred by VarLLant (6, p. 357) to Naidium. The chief reasons for believing it to be a member of the genus Pristina are the absence of eyes, and the commencement of both dorsal and ventral setae upon the same segment. The dorsal setae are capillary only. The intestine is said to have a spiral arrangement. The worm occurs in Louisiana, Central America, Cuba, and Jamaica. (1) Pristina longiseta, EnREnBERG. P. longiseta, EHRENBERG, Symb. Phys. 1828. Pristinais longiseta, GERVAIS, Bull. Ac. Roy. Belg. 1838, p. 17. Nais longiseta, D UpDEKEM, Bull. Ac. Roy. Belg. t. xxii, pt. ii. 1855, p. 552. Stylaria longiseta, Tauber, Ann. Dan. 1879, p. 73. Definition. Length, 8 mm.; number of segments, 20. Dorsal setae: of segment III muck longer than the other. Prostomium long. Glandular ventricle in segment VIII. Five vascular arches connecting dorsal and ventral trunks. Nephridia commence in X. Hab.—LEurope. 1 It is possible that ‘Lumibricus hirsutus’ of DatyELu (p. 140) is referable to this genus. DESCRIPTIONS OF GENERA AND SPECIES 291 This is a small species, not measuring more than 8 mm., or 2 mm. according to Lerpy. VAILLANT has thrown some doubt upon the identity of the American and European forms on account of this difference in size. It may also be pointed out that Vespovsky’s figure of this species (24, Taf. ii, fig. 13) indicates no abrupt demarcation between the buccal segment and the comparatively short prostomium; in the text (24, p. 31) it is remarked ‘Der Kopflappen verjiingt sich allmalig zu einem konischen, fadenformigen Riissel.’ This ‘gradual’ narrowing is not shown in LErpy’s figure, nor in D’UDEKEM'S; and in a single example (English, but ?exact locality) examined by myself, the prostomium was as illustrated by Lerpy and p’UpDEKEM, not VEJDOVSKY. The specimen examined by me being about 4-5 mm. in length connects the two extremes of 2mm.and 8mm. As VEJDOVSKY leaves out Lerpy’s Pristina longiseta in the list of synonyms given under the species, and does not mention N. America as a locality for the species, but is acquainted with Lurpy’s paper', I am disposed to infer that VEsDovsKY is not certain about the identity of his and Lrrpy’s varieties. The question must, I think, be left open for the present. The prostomium appeared to me to be grooved upon the lower surface, this groove opening into the mouth. The number of segments is 17-20. The dorsal setae are entirely capilliform, two or three are found in each bundle’; those of the third segment are, according to VrsJDOVsKY’s figure, about three times the length of those of other segments. The ventral setae are sigmoid and cleft at the extremity; there are seven or eight to a bundle. The peculiarities of the alimentary canal have been referred to under the genus. The dorsal vessel is connected with the ventral by four pairs of vascular arches in segments iv-vii (VEspovsKY, 21, p. 113), of which the last pair is stouter than the rest. These vessels are entirely unbranched and arise from the dorsal vessel just behind the dissepiment. The nephridia commence in the tenth segment. The perivisceral corpuscles have black, brown, or green contents. VoELTzkow has recorded from Madagascar a species very like P. longiseta, but no special description is given. (2) Pristina equiseta, Bourne. P. equiseta, Bourne, Q. J. M.S., vol. xxxii (1891), p. 352. Definition. Length, 8 mm.; number of segments, 21. Setae of segment III not elongated ; prostomium long. Glandular ventricle in segment VIII. One vascular arch, Nephridia commence in IX. Hab.—England (?). This species was discovered by Bouryz in the ‘ Victoria regia ’* tank, in the Gardens of the Royal Botanical Society, in Regent’s Park, London, whence I had myself 1 Jt is not only quoted in list of literature, but the species is referred to in the history of the group, p. 23. 2 Three to six are figured by Vrspovsky, three by Lempy and p’UpEKrM. PpeZ 292 OLIGOCHAETA obtained specimens. It may not, therefore, be a native of this country. It measures 8mm. in length and consists of 18-21 segments. The most prominent difference from the last species is the absence of specially elongated setae from the dorsal bundles of segment iii. This is shown in an illustration (Zincograph)' facing p. 337 of the memoir. The ventral setae of the fourth segment were often larger and stouter than the rest; it is suggested that these may be genital setae, though no other indications of sexual maturity were met with. The segment in which the single pair of commis- sural vessels lie is not mentioned. The coelomic corpuscles are large and greenish ; sometimes quite black owing to quantity of secreted particles. On account apparently of these the worms look of a chalk-white colour when seen with the naked eye or a lens. (3) Pristina breviseta, Bourye. P. breviseta, BourRNE, loc. cit. p. 353. Definition. Dorsal setae of two kinds, capilliform and hastiform, the latter cleft at extremity. Capilliform setae of segments II and III shorter than following. Nephridia commence in IX. Hab.—Madras. This Pristina is larger than the other species, and consists of about forty-six segments. It differs from all the species of the genus except P. lutea in having bifurcate setae in the dorsal bundles. The shape of these, however, is a little different in the two species. The coelomic corpuscles ‘are black and very noticeable.’ It has ebeen mentioned above that this genus is characterized by having only one cephalized segment, as in the vast majority of Oligochaeta. This condition, however, appears, so far as the present genus is concerned, to be secondary. Both in this species and in the last Pourne has found that the newly budded head consists of seven segments. (4) Pristina lutea (O. Scumipt). Naidium luteum, 0. Scumipt, Froriep’s Notizen, iii. 1847, p. 322. ? Nais caecilia, Mayer, SB. Niederrh. Ges., 1859, p. 45. Definition. Length, 15mm. ; number of segments, 30. Dorsal setae, capillary and hastiform. Hearts in V-VII. Glandular ventricle in VIII. Hab.—Elbe. I have already indicated (p. 289) the reasons which appear to me to render necessary the inclusion of this species in the genus Pristina. Our knowledge of its structure is chiefly due to Vespovsky (24), who has illustrated his description. DESCRIPTIONS OF GENERA AND SPECIES 293 (5) Pristina proboscidea, new species. Definition. Dorsal setae capillary. Prostomium very large as in N. lacustris. Hab.— S. America. On a casual glance this would be undoubtedly referred to the species W. lacustris. As Bourne has found in JX. lacustris dorsal setae occasionally present on some of the segments normally devoid of them, the present worm may be an extreme variation. Genus RIPISTES, Dusarpin. Pterostylarides, CZERNIAVSKY. Stylaria, O. ScumipT (in part.). Nais, GREBNITZEY (in part.). DEFINITION. Prostomium elongated. Dorsal setae commence in the sixth segment, the first three pairs of bundles containing setae of great length; ventral setae commence in the second segment, but are absent from IV and V. Eyes present. Though neither VEsDovsKy (24), nor VAILLANT (6) accept this genus, I think that Bourne (5) is quite right in emphasizing its distinctness from Stylaria. But in using CZERNIAVSKY'S name Pterostylarides, the name Ripistes of DusarDin, which clearly has the priority, was overlooked (as VAILLANT, 6, p. 366, has pointed out). CzERNIAVSEKY’S definition does not include a reference to what is really the most important character of the genus, viz. the absence of both dorsal and ventral setae from segments iv and v. But the description of the three pairs of extremely long dorsal setae leaves no room for doubt as to the identity of Pterostylarides and Ripistes. The characters of the cerebral ganglia strengthen the arguments for regarding ‘ Stylaria parasitica’ of O. ScumipT as the type of a genus distinct from Stylaria. It is, according to VesDovsky’s figure (24, Pl. ii, fig. 10), very short—not prolonged backwards, as is the case with Nazis. There are two species, viz. R. para- sitica and R. macrochaeta. (1) Ripistes parasitica (O. ScumipT). Ripistes sp., DuJARDIN, Proc.-Verb. Soc. Philom. Paris, 1842, p. 93. Stylaria parasitica, O. ScumipT, Froriep’s Notizen, iii, 1847, p. 321. Nais parasitica, GREBNITZKY, Zapiski novoross. Obstch. Est., 1873, p. 268. Pterostylarides parasitica, CzERNIAVSKY, Bull. Soc. Nat. Mose., 1880, p. 310. Definition. Length, 6mm.; number of segments, 20; prostomium about as long as peristomial 294 OLIGOCHAETA segment. Tentral setae of segments II and ILI about one-third longer than setae of other segments. Five or sia setae in the anterior bundles, seven or eight in the others. Twelve to fifteen setae in three anterior dorsal bundles, all very long. Hab.—Europe. This species has been chiefly studied by Vespovsry (24, PI. ii, figs. 8-12). (2) Ripistes macrochaeta (Bourne). Pterostylarides macrochaeta, BournE, Q. J. M.S., vol. xxxii, p. 349. Definition. Prostomium much longer than peristomial segment. Ventral setae bundles of segments II and III consist of two or three setae, those of other segments of two to five setae. Three anterior dorsal seta bundles contain each two to five very long setae, the rest being shorter than the other dorsal setae. Hab—England. This species was described, with an illustration, by BouRNE, in 1891. The descrip- tion is limited to the external characters which alone are. indicated in the figure. A note appended to the description of the species by ‘E.R. L.’ states that ‘the long setae are frequently found thrown forward go as to partly encase and protect the head when the worm forms for itself a temporary tube. They are also used to strike the water in swimming.’ Genus UNCINAIS, LEVINSEN. Syn. Paranais, CZERNIAVSEY. Nais, AUCT. Clitellio, VAILLANT (in part.). Ophidonais, VEJDOVSKY (in part.). * Enchytraeus, Minor (in part.). DEFINITION. Setae entirely uncinate; dorsal setae commence in segment V. On segment V of sexually mature individuals genital setae replace the ordinary ventral setae. Glandular ventricle present. No nephridia (?). Testes (one pair) in VIII and IX. Ovaries in X. Spermathecae in V. Eyes absent. The only well-known species of this genus is U. littoralis ; under this heading the synonymy of the species and genus will be discussed. The above generic definition is entirely compiled from Bourne’s (5) notes upon U. littoralis, which establish its generic rank. Bourne figures a budding worm and also the reproductive organs and setae of the sexually-mature worm. The most remarkable external characters of the genus are the existence of uncinate setae only, in both dorsal and ventral setae, and the absence of the dorsal setae from all segments DESCRIPTIONS OF GENERA AND SPECIES 295 anterior to the fifth. These points distinguish it from all other genera of Naidomorpha. The vascular system consists of a dorsal and ventral vessel which run to the end of the body. In segments ii-iv they are joined by three pairs of circular vessels, which are branched, and, according to Bourne's figure (5, fig. 2), form a network comparable to that of NV. yosinae, or perhaps more like that of N. heterochaeta ; but there is no irregularity in the origin of the circular vessels, and there are fewer pairs of them. In segments v—vii the dorsal and ventral trunks communicate by means of unbranched circular vessels. BouRNE records the interesting fact that in the young buds com- missural vessels occur in all the segments. The absence of nephridia is, if confirmed, a very remarkable character. Behind the pharynx occur a pair of glands which probably represent the pharyngeal glands of Nais and other genera. The arrangement of the sexual organs differs from that found in Mais and in Clitellio, to which genus the worm has been referred by VAILLANT. They indicate, however, a transition between the more typical Naids and the Tubificidae. As in the Naids the paired spermathecae lie in segment v, opening in front of the genital setae which replace the ventral setae of this segment; the pouches are oval in form and restricted to the fifth segment. The genital setae are ‘very stout, and longer than the ordinary setae, and they possess a mere rudiment of the crotchet at the free extremity. The testes and ovaries lie further back than in other Naids, but a segment in front of the position which they occupy in the Tubificidae. The testes', of which there are only a single pair, occupy nearly the whole of segments viii and ix; each testis is continuous through the septum which separates these segments—a condition which seems to be paralleled only in the case of the genus Phreodrilus. The ovaries lie in the following segment—the tenth. Neither oviducts nor sperm-ducts are mentioned or figured. (1) Uncinais littoralis (0. F. Mtxuer), Nais littoralis, O. F. Mtuier, Zool. Dan. 1788, ii, p. 54. u Paranais littoralis, CZERNIAVSKY, Bull. Soe. Nat. Mosc., 1880, p. 311. Uncinais littoralis, Levinsen, Vid. Med. 1883, p. 218. Clitellio (Clitellio) arenarius, VAILLANT, Annelés, p. 415. Definition. Prostomium blunt and rounded. Setae of segments II, III, IV longer and thinner than those which follow. Ventral setae of most segments thicker and shorter than dorsal setae. Hab.—Europe. 1 Possibly the structures called ‘testes’ and ‘ovaries’ by Bourne are sperm-sacs and egg-sacs. 296 OLIGOCHAETA The synonymy of this species is a matter of great difficulty. It has been confounded with; Clitellio arenarius by VAILLANT. Having myself investigated Clitellio arenarius of CLAPAREDE (8), I can state positively that it is not identical with Paranais littoralis of BouRNE. ZENGER'S Peloryctes inquilina being probably synonymous with Hemitubifex benedii, must also be removed from VAILLANT’S list. As D’'UDEKEM would hardly have overlooked a cephalization in his ‘ Tubifea hyalinus, if it existed, it is probably safe to remove this species also from the list; it is indeed queried by VAILLANT. Another synonym queried by VAILLANT is Monopylephorus rubroniveus of LEVINSEN; I am disposed to regard this as congeneric with Bothrioneuron of Stouc. As there is nothing in CZERNIAVSKY’S definition of the genus Paranais, or of the species P. littoralis to warrant its identity with the species described by BoURNE under the name of Paranais littoralis, I venture to use the generic name Uncinais of LEVINSEN, the definition of which does fit in. The following are the definitions referred to. CZERNIAVSKY. ‘Setarum fasciculi utrimque bi-seriati, omnes et superiores et inferiores setis uncinatis formati. Corpus lineare teres, postice subtruncatum. Ocelli duo vel nulli” -LEVINSEN. ‘Alle Borsterne Krogb¢rster . . . Rygbdrster mangle i de f¢rste 3 b¢rsteberende Ringe; kun forste Rings Bé¢rster tydelig lengere end de gvrige 5-6 i hvert Bundt, senere 3-4; ¢verste Bé¢rstegren noget smallere end nederste.’ (2) Uncinais uncinata (OErsTEzD). Nais uncinata, OERSTED, Nat. Tidsskr. 1842, p. 136. Enchytraeus triventralo-pectinatus, Minor, Am. Journ. Sci. Arts, xxxv, 1863, P. 35: Paranais uncinata, CZERNIAVSKY, Bull. Soc. Nat. Mosc., 1880, p. 311. Ophidonais uncinata, VEJDOVsKY, Syst. u. Morph., 1884, p. 24. Uncinais uncinata, Levinsen, Vid. Med., 1884, p. 218. Definition. Length, 11 mm. ; number of segments, 29-25. Setae four in each bundle, always of the same size. Hab.—Europe ; America. Genus BOHEMILLA, VEsDovsky. Syn. Nais, Timm. DEFINITION. Dorsal setae begin on segment V; the longer dorsal setae serrated. Eyes present. This genus, instituted by VespovsKy, seems to be a perfectly good one. It only contains one species, viz. Bohemilla comata, VresDovsky. B. comata, Vespovsxy, SB. Bohm. Ges. 1883, p. 218. Nais hamata, Timm, Arb. Zool. Zoot. Wiirzb., 1883, p. 152. DESCRIPTIONS OF GENERA AND SPECIES 297 Definition Length 6mm. ; number of segments 38. First pair of ventral setae bundles larger than those in two following segments; those of IV very small, sometimes absent. Hab. —LHurope. This species has been chiefly investigated by Vespovsxy. Genus DERO, OkEn. Syn. Proto, OERSTED. Uronais, GERVAIS. Xantho, DuTROCHET. Aulophorus, SCHMARDA. Nais, O. F. MULLER (in part.). DEFINITION. Dorsal setae capilliform and hastiform, commencing upon the sixth segment. Branchial processes present at hinder end of body. Eyes absent. Inhabit tubes The principal character of this genus is, of course, afforded by the branchial processes at the end of the body, which are dorsal in position. These are ciliated processes of the integument containing blood-vessels; they really spring from the expanded and funnel-shaped termination of the anus, and there are rarely more than four of them (only in D. mwultibranchiata). Sometimes the occurrence of six or even eight branchial processes has been asserted. In such cases it is the margin of the funnel-shaped expansion, which is drawn out into processes; a pair of these are extraordinarily long in Dero furcata. The members of this genus usually (? always) inhabit tubes, which are formed by a viscid secretion from the worm’s body to which small extraneous particles adhere. A species investigated. by myself (25), of whose identity I am not certain, was invariably found in the interior of the stems of dead and decayed aquatic plants. D. vaga walks abcut with its tube like a Caddis worm. The genus is also to be characterized by the complete absence of floating peri- visceral corpuscles (except in D. vaga), which are so distinctive a feature of many Naids. Other points in its structure have been already dealt with. The genus Dero is widely distributed like many, if not all, of the aquatic Oligochaeta. It occurs in Europe, North America, the Philippines, Ceylon (if Aulophorus oxycephala of ScHMARDA be really a Dero), and finally, I have received specimens from Mombasa in East tropical Africa. The distinction of species is a matter of some difficulty. Vart~tant allows as many as nine; BovusFIELD only seven, but this number must be increased by two, for BoUsFIELD was not acquainted with REIGHARD’s observations upon D. vaga, and D. multibranchiata has since been described. Of BousrimLp’s seven species, Qq 298 OLIGOCHAETA four: viz. D. latissima, D. perrieri, D. miilleri, and D. acuta, are described for the first time by himself and not noticed by VarLuant. The remaining three are D. obtusa, D. limosa (=D. philippinensis), D. furcata (=D. palpigera, and D. rodriguezit) ; D. digitata (Nuis digitata, O. F. Miizer) is mentioned as ‘doubtful.’ The species not referred to by BousFIELD, but included in this genus by VAILLANT are Pristina flagellum of Leipy, Aulophorus oxycephala of ScumaRDA, Xantho decapoda of Durrocuet ; D. palpigera and D. philippinensis are considered to be distinct species. P. flagellum does not seem like to be referable to the present genus by reason of the fact that the dorsal setae commence from the very first—that there is no cephalization like that of Dero. It is just possible that P. flagellum belongs to my genus Branchiwra. D.decapoda is too imperfectly known to permit of its being regarded as a distinct species. It is said to have ten appendages from the branchial area. D. palpigera is so imperfectly described by GReBNITzKy that I have no wish to criticize the view advanced by Semper that it is the same as his D. rodriguezi, and by Bousrierp that both are identical with D. furcata. It is very difficult to identify Xantho hexapoda of Durrocuet, Nais awricularis of Bosc, which BousFIELD regards, and with great probability as a Dero, and Avulo- phorus discocephalus of ScumaRDA. No doubt BousFIELD is also right in stating that it is impossible to identify D. digitata of Mitutuer. I do not admit for the present D. stuhlmanni of SttrrEN, The only distinctive character appears to be its very small size (2 mm.), though size is sometimes, I believe, a reason for specific distinction. D. intermedia of CRraGin is doubtful. Nais caudata of ScumarDa, with lengthened » posterior segment, may also be a Dero. » (1) Dero miilleri, Bousrie.p. D. miilleri, BousrreLp, J Linn. Soc. 1886, p. 104. Definition. Length, 13 mm.; number of segments 95. Branchial processes, oblong, quadrangular, lower longest. Hearts usually seven pairs. Hab.—Great Britain. This species is easily to be distinguished on account of the peculiar form of the branchial processes. (2) Dero limosa, Lerpy. D. limosa, Leipy, Am. Nat. 1880, p. 421. D. philippinensis, Srmper, Arb. Zool. Zoot Wirzb. 1877/78, p. 107. D. acuta, BousrieLp, Rep. Brit. Ass., 1885, p. 1098. Definition. Length, 6 mm.; number of segments 60. Branchial area with dorsal lip which DESCRIPTIONS OF GENERA AND SPECIES 299 2s prolonged into two moderately long processes. Five pairs of contractile hearts. Hab.— Europe; N. America ; Philippines. BOUSFIELD (8) insists upon the identity of Lerpy’s and Sempen’s species with a Dero studied and figured by himself. I am a little uncertain whether a species, concerning which I gave a few anatomical details a year or two since, and which I have already referred to as living inside the dead stems of water plants, is also identical. If so, there are six pairs of hearts and not five, and the first of these give off a branch on either side running forward. The hearts are in segments vi-xi, and those of vii, viii, ix are stouter than the rest. I regard D. acuta of BousFrrELD as merely a variety of the above; the branchiae are said to be longer. In this STIEREN agrees. (3) Dero furcata, OKEN. D. furcata, OKEN, Lehrb. d. Naturg. iii, Pt. i, 1815, p. 363. ? D. palpigera, GREBNITZKY, Zapiski novoross. Obstch. Est. 1873, p. 268. ? D. rodriguezii, SzempER, Arb. Zool. Zoot. Wiirzb. 1877/78, p. 106. Definition. Number of segments 35. Dorsal setae bundles commence in the fifth segment. Body ends in two long processes, and there are also a pair of supplementary branchiae at sides. Five pairs of contractile hearts. Hab.—Kurope; Trinidad This species was obtained by BousrizLp from the inside of dead stems in water from the Royal Botanic Gardens, Regent’s Park, by Szemprr from Minorca; I have received apparently the same species from Eastern tropical Africa. BousFrreLp, after remarking that ‘D. rodriguezii is undoubtedly the same as the A. vagus of Lxrpy, D. furcata of OkzEN, and D. palpigera of GREBNITZKY, omits the second name in his list of synonyms. Semper’s figure (1, Taf. iv. fig. 15) represents the supple- mentary brancbiae as springing from the anal area like the other branchiae. STIEREN received this species from Trinidad. (4) Dero perrieri, BousFi=Lp. D. perrieri, BousFrrELD, Rep. Brit. Ass. 1885, p. 1098. D. obtusa, Perrier, Arch. Zool. Exp. 1872, p. 65. : Definition. Number of segments, 35. Branchial area with entire margin. Hearts three to five pairs. Hab—Europe. BousFIELD is, no doubt, right in distinguishing between D. obtusa of D’UDEKEM and D. obtusa of PERRIER. The entire margin of the gill-area in PerRior’s species Qq 2 300 OLIGOCHAETA is not found in the true D. obtusa. It is probably this species whose anatomy I myself described (22). (5) Dero obtusa, D’UDEKEM. D. obtusa, D'UDEKEM, Bull. Acad. Roy. Belg. xxii, pt. ii, 1855, Pp. 549- Definition. Number of segments, 50. Branchial area with distinct dorsal lip marked off by deep grooves on each side; branchiae rather short. Hearts usually four in number. Hab.— Europe. BousFig£LD (1) remarks that ‘this species shows the first trace of the modification which leads to the formation of supplementary branchial processes in the distinct demarcation of the dorsal lip, at the angles of which they are borne by those species which possess them.’ (6) Dero vaga (Lerpy). Aulophorus vagus, J. Leipy, Am. Nat. 1880, p. 423. D. vaga, L. Vartuant, Annelés, p. 383. Definition. Length, about 8 mm. ; number of segments, 25. Body ending in two long processes ; branchiue rudimentary, only two slight processes. Dorsal setae bundles consisting of one capilliform, and two pectinate setae. Perivisceral corpuscles present. Contractile hearts im VIL, IX, X. Hab.—N. America; Trinidad. This species, imperfectly described by Lzrpy (10), has been more fully studied and illustrated by ReraHarD. The most marked characteristic of the species is the very rudimentary condition of the branchia, and the existence of two long processes, as in D. furcata. The vascular loops in the “branchial region are correspondingly simple. The dorsal vessel bifurcates a little in front of the tail, and joins a circular vessel, which is again connected with the ventral vessel. On either side of the point, where the ventral vessel arises, a slender trunk springs and forms a low loop in the two rudimentary branchial processes, and there joins the dorsal vessel, just after its bifurcation. The ‘spade-shaped’ setae of the dorsal bundles are peculiar to this species. Their outer ends are flattened, the expansion being supported by two or three ribs. STIEREN received examples from Trinidad. (7) Dero latissima, BousFiELp. D. latissima, BousFIELD, Rep. Brit. Ass. 1885, p. 1098. Definition. Number of segments, 40. Four pairs of hearts. Branchial area with entire margin, wider than long; branchiae long. Hab—Great Britain. DESCRIPTIONS OF GENERA AND SPECIES 301 This species has been described by BousFrELD in two papers (2, 8), in the later of which (8, Pl. iv. fig. 8) the branchial area is illustrated. The definition does not appear to me to be enough to distinguish it from D. perrieri, but, as BousrreLD has examined both species, I leave it. (8) Dero multibranchiata, Srieren. D. multibranchiata, STIEREN, SB. Dorpat. Nat. Ges,, 1892, p. 103. Definition. Length, 8mm. ; number of segments, 65. Branchiae fourteen in number, elongated. Hab.—Trinidad. This species, which has been somewhat fully described by STIEREN (with a few illustrations), is, of course, to be distinguished by the gills. The shorter dorsal setae do not appear to be bifid. Genus CHAETOBRANCHUS, Bourne. DEFINITION. Fore end of body with a series of pairs of hollow processes of the body-wall, which enclose the dorsal setae, gradually diminishing in size posteriorly. Dorsal setae, which commence in second segment, capilliform, increasing in length up to about the tenth segment; thence diminishing in posterior segments; sickle-shaped setae also present; ventral setae entirely uncinate. No glandular stomach. This is quite the most remarkable genus of the family at present known. Its distinguishing feature is the presence of a double series of long hollow processes of the integument, which enclose the dorsal setae, at least in the anterior seg- ments; posteriorly—from the forty-second segment onwards, according to BouRNE’s figure (1, Pl. xii. fig. 1), some of the dorsal setae are not so enclosed. These branchial processes, as BouRNE assumes them to be, diminish in size after the first dozen pairs until ‘they become mere warts on the surface of the worm, and in the posterior segments are entirely absent. There are from sixty to seventy pairs of them. Each process is hollow, its interior communicating with the coelom; the walls are formed of epidermis alone, the muscular layers of the body-wall being apparently not prolonged into it ; the epidermis has a cuticle, through which project very fine cilia; at the extremity are a few stiff hairs, doubtless of sensory function, and similar to hairs generally distributed over the body in the lower Annelids. Each branchial process contains a vascular loop, which is derived from the-circular vessel 302 OLIGOCHAETA uniting the dorsal and ventral trunks of its segment. At present there are only three other Oligochaeta in which branchial processes exist, viz. Dero, Branchiura, Hesperodrilus branchiatus, and Alma nilotica (=Digitibranchus niloticus); it is not, however, yet certain whether the latter worm is really an Oligochaet. The setae of Chaetobranchus are arranged as in Pristina and Naidium, that is to say, there is no cephalization; both the dorsal and ventral bundles commence in the second segment. The dorsal setae are of two kinds; there are long capilliform setae, which vary in length, being longest in some of the anterior bundles; in the posterior bundles there are in addition sickle-shaped setae which have a straight shaft, and a curved, sickle-shaped extremity; these two extremes are connected by intermediate forms. The ventral setae are all uncinate; there are four to six of them in each bundle. The viscera do not present any features of special interest. The alimentary canal differs from that of most Naids in having no glandular ventricle. Nephridia are present, but there are no data as to the segment in which they commence. Bourne says that they resemble the nephridia of Naids generally. The coelomic corpuscles are round, and contain numerous olive-green granules; as they can pass from segment to segment, it is evident that the septa must be imperfect. The vascular system consists of the usual dorsal and ventral trunks, which are connected in each segment by a pair of lateral vessels. The dorsal vessel is much pigmented. There are no eye-spots. Of the generative organs, unfortunately, nothing is known. The genus only contains one recognizable species at present, viz.— Chaetobranchus semperi, Bourns. C. semperi, Bourne, Q. J. M.S. vol. xxxi, p. 88. Definition. Length, 25-50mm. Branchial processes, 60-70 pairs. Ilab.— Madras. This species, of which a general account is given above, was discovered by Bourne in a ‘tank’ in Madras town!. It lives in the weed, moving about freely, and not constructing any tube, though forming a burrow. All the individuals found were in an active state of multiplication by simple fission, and were in no case sexually mature. BouRNE considers that this Naid is either identical with, or closely allied to, the worm described by Semper (1) as occurring along with Dero philippinensis. ‘ I found specimens in the Victoria regia tank at the Botanical Society’s Gardens, Regent’s Park. DESCRIPTIONS OF GENERA AND SPECIES 303 Genus AMPHICHAETA, TavBER. DEFINITION. Prostomium elongate. Setae in four rows; several segments without setae after second setigerous segment No perioesophageal vessels. Sperm-sacs and egg-sacs present; no genital setae. This genus was first described by TauBer (1); the description, however, is limited to the following brief definition :— ‘Praestomium dilatatum. Os inferum. Fasciculi uncinorum tam dorsalium quam ventralium.’ This definition is nevertheless sufficient to show that the worm in question is different from Chaetogaster. The genus has been fully established by the investigations of KaLLsTENIus. Previously to the paper of the last-named, LEVINSEN (2) had sought to identify Amphichaeta with Uncinais. Since LEVINSEN wrote upon this subject Uncinais has been re-investigated by Bourne (5); and there is no longer any doubt of the complete distinctness of these two Oligochaeta. In the most distinctive feature of the organization of the Chaetogastridae, Amphichaeta agrees with Chaetogaster; there are, that is to say, a considerable number of segments intercalated between the second and third seta-bearing segment ; in Chaetogaster there are six intervening between the first segment and the second segment, provided with ganglia. The oesophageal segment has no setae; in Amphi- chaeta there are the same number; but as there are two ventral bundles of setae immediately following the mouth, and as the oesophageal segment is provided with setae, the same number of ganglia separate the anterior and the posterior seta-bundles. This genus also differs from Chaetogaster in the absence of a perivisceral vessel in the oesophageal segment. A peculiar fact about the nephridia is their asymmetrical condition ; they commence in the segment following that which contains the ovaries ; occasionally they are symmetrical (paired), but more often one or other only of the two nephridia of a segment are present; they are closely adherent to the ventral blood-vessel, and are entirely without a pre-septal portion, that is, there is no funnel. The reproductive organs have been fully described by KaLustTentIus; the two testes lie in the segment immediately following the oesophageal; they arise from the peritoneum covering the nervous cord; the unpaired ovary arises in a similar fashion in the next segment; the efferent apparatus of the testes consists of the usual funnel-duct and terminal gland; it opens on to the ovarian segment; an 304 OLIGOCHAETA important difference between Anvphichaeta and Chaetogaster is the presence in the former genus of sperm-sacs and egg-sacs; these are situated dorsally to the intestine, and consist of outgrowths of the anterior septa of the testicular and of the ovarian segments ; they extend, when fully developed, into the third segment after the ovarian segment; the sperm-sac comes to lie within the egg-sac. These sacs are not found in Chaetogaster. A further difference from Chaetogaster is in the absence of genital setae. The ventral setae of the ovarian segment are quite absent in fully mature worms. This segment, as well as the one in front, is occupied by the clitellum. The testicular segment contains, in addition to the testes, the spermathecae; these are placed behind the anterior septum of that segment. The genus Amphichueta, although it should clearly be placed in the formerly-used family Chaetogastridae, on account of the peculiar ‘cephalization’ and the structure of the alimentary canal, differs from that family, and approaches the Naidomorpha in the presence of sperm-sacs and of egg-sacs; the absence of genital setae removes it from other Chaetogastridae, and brings the genus near to such a genus as Dero, where, as I have shown, there are no genital setae; as a rule, these setae are present in the Naidomorpha. . (1) Amphichaeta leydigi, Tauber. A. leydigi, TaAuBER, Ann. Dan. 1879, p. 76. Definition. Ove sefa in first lundle, 2-4 in the rest. Hab.—Denmark ; Germany. , (2) Amphichaeta sannio, Ka.tstentvus. a A. sannio, KALLSTENIUS, Biol. Féren. Férh. 1892, p. 54. Definition. Length, 1-5 m.; four setae in cach of three anterior seta-bundles, aflerwards three. Hab.—Sweden ; Baltic. Genus CHAETOGASTER, von Bazr. Syn. Nais, Lamarcg, &c. (in part.). Mutzia, Voat. Derostoma, Ducis. DEFINITION. Ventral seta-bundles only present, composed of uncinate setae. The first in segment II. Segments ITI-V without setae at all (except in Ch. filiformis). One pair only of commissural blood-vessels. DESCRIPTIONS OF GENERA AND SPECIES 305 I follow LanKEsTER (note appended to Bournz’s paper 5) in relegating the genus Chaetogaster to the family Naidomorpha; so long as the genus Chaetogaster alone was known, the entire absence of the dorsal seta-bundles might possibly be held to be of sufficient importance to keep it as the type of a distinct family, though doubtfully, in view of analogous differences in the family Enchytraeidae ; now, however, that another genus, closely allied to Chaetogaster, viz. Amphichaeta, is known, there is not this excuse for retaining the family; no other structural differences of first- rate importance support such a separation of the Chaetogastridae as a distinct family. The absence of the ventral setae in a number of the anterior segments (not from the first) was a peculiarity which might possibly merit emphasis of this kind, were it not for an analogous absence from two segments of the ventral setae in Ripistes macrochaeta, The reproductive organs, whose modifications are frequently of family value, are constructed upon precisely the same lines as in other Naidomorpha; and the spermathecae, testes, &c., are in the same segments in both of the ‘families’ Naidomorpha and Chaetogastridae. I have mentioned as a characteristic of the genus the fact that there is only a single pair of commissural vessels uniting the dorsal and ventral vessels; this is not absolutely distinctive, since Bourne found, and I have been able to confirm his discovery, that in Pristina equiseta there is but a single pair of such vessels. A marked characteristic of the present genus is the series of dilatations of the oesophagus; in Ch. crystallinus, for example, there are two of the dilatations following the pharynx; each is covered with a network of blood-vessels ; they, no doubt, correspond to the ‘magen-ahnliche’ dilatation in many Naids. But they are absent in Ch. filiformis, which is very Naid-like. The absence of an intimate correspondence between the nerve ganglia, the inter- segmental septa, and the setae is remarkable. The first septum occurs behind the pharynx and there are three ganglia in front of it, to which there are only one pair of setae bundles. The remarkable double character of the ventral nerve cord in the anterior segments has already been commented upon. The nephridia of the genus, like those of Amphichaeta, are without a funnel; the place of this is taken by a rosette-shaped bunch of cells attached to the anterior septum of the segment by a few muscle fibres. The development of the nephridium has been traced by VEJDoVsKY, who found no trace of a funnel at any time; the earliest stage which he figures consists of three cells, all of them lying behind the septum. The mature organ consists of tubes running parallel to each other for the greater part of their course; they are connected by numerous small tubules, which also branch within the secreting cells. Rr 306 OLIGOCHAETA As to the species of the genus, VAILLANT allows seven; but two of these are, as he himself admits, doubtful; the two doubtful species are Ch. filiformis of SCHMARDA and the Derostoma laticeps of Duais. With regard to the former, which is figured, though very insufficiently, it is certainly a member of the genus. ScHMARDA figures setae upon every segment of the body. It comes from Curaca, in South America ; I have examined a specimen from Valdivia. Derostoma laticeps, at first referred by Ducts to the Planarians, was afterwards (8, p. 30) placed in the genus Nais; but no particulars are given save that there is only a single set of setae on each side of the body, and that the ‘lip’ is large (suggestive, as VAILLANT has pointed out, of an Aeolosoma). Whether Ch. gulosus of Lrtpy (8, p. 124) is a ‘good’ species or not seems doubtful. There is really nothing in the description which is at all decisive in the matter. Its length is one line, and there are five or six setae in each bundle. The oesophagus is said to be short. I allow the five following species, and I use Vespovsky’s names. This because it does not seem to me to be possible to identify the Nais vermicularis of MOLLER. The only distinguishing feature of it is its length (2 lines). That possibly brings it nearer to Ch. diastrophus, but the identification does not appear to me to be certain. (1) Chaetogaster limnaei, v. Barr. Ch. limnaei, v. Barr, Nov. Act. Nat. Curios., 1827, p. 611. Ch. furcatus, EHRENBERG, Symb. Phys., 1828. _ Ch. diaphanus, OrrsTED, Nat. Tidsskr., 1842, p. 138 (in part.). Ch. vermicularis, Grube, Arch. f. Nat., 1851, p. 353 (in part.). Mutzia heterodactyla, Voet, Arch. f. Anat. Phys., 1841, p. 36. Definition. Length, 2 mm, » oesophagus much sebical Hab.— Europe. This species lives parasitically upon fresh-water Mollusca and sometimes within their bodies. It is the smallest species of the genus. The anterior pair of setae are commonly somewhat stronger than the rest. The first pair of nephridia open in front of the second setae bundles. (2) Chaetogaster diaphanus, GRUITHUISEN. Ch. niveus, EHRENBERG, Symb. Phys., 1828. _. Ch. diaphanus, OERsTED, Nat. Tidsskr., 1842, p. 138 (in part.) Ch. vermicularis, Grube, Arch. f. Nat., 1851, p. 353 (in part.). Nais diaphana, GRUITHUISEN, Nov. Act. Nat. Curios., 1828, p. 409. Nais lacustris, DALYELL, Powers of Creator, vol. ii, 1853, p. 130. Nais scotica, JouNsTon, Cat. Worms B. M., 1865, pp. 71 and 336. DESCRIPTIONS OF GENERA AND SPECIES 307 Definition. 15 mm. in length ; oesuphagus very distinct but shorter than pharynx. Hab.— Lurore. This species is the largest of the genus and completely transparent. VEJDOVSEY considers that the Ch. diaphanus of D’'UprKEM (4), who described the genitalia, is not the same species, but is Ch. cristallinus. VAILLANT, by omitting this particular reference from his list, seems to concur. I would point out that the ‘ yellow globules’ described and figured by DALYELL are probably the ripe ova. The genital organs of Ch. cristallinus are, however, unknown, and b'UpEKEm’s Ch. diaphanus is only 5 mm. long, which better suits Ch. cristallinus. I include N. scotica as a synonym on the authority of JonnsTon, who regarded it as being the same as DayeEu’s N. lacustris. (3) Chaetogaster cristallinus, Vespovskxy. Ch. cristallinus, VEJDovsky, SB. Bohm. Ges., 1883, p. 220. Definition. Length, 2-3 mm. Dorsal and ventral blood-vessels not continued into pharyngeal region. Ovsophagus as long as pharynx. Hab.—Europe. This species was first described, and was later (24) more fully described and figured, by VesDovsKy. VAILLANT regards, I think with some reason, LANKESTER’s Ch. niveus as probably identical with this species. The principal reason for the identification is the long oesophagus. The dorsal vessel of this species ends in a bunch of cells abruptly ; just before its termination it passes through a sling attached to the first dissepiment. (4) Chaetogaster filiformis, Scumarpa. Ch. filiformis, Scumarpa, Neue wirbell. Thier., I. ii, 1861, p. 11. Definition. Length, 2 mm. Prostomium well developed ; no missing ventral setae. Hab.-— 8. America. This species is curiously intermediate between Nais and the typical Chaetogaster. It has no dorsal setae as in Chaetogaster ; but it has a well-developed prostomium, and no narrow oesophagus, in which points, of course, it departs from Chaetogaster. (5) Chaetogaster diastrophus, GRUITHUISEN. Ch. vermicularis, GruBE, Arch. f. Nat., 1851, p. 353 (in part.). ? Ch. miilleri, p’'UpEKEM, Bull. Ac. Roy. Belg., xxii., pt. ii, 1855, p. 554. Nais diastropha, GRUITHUISEN, Nov. Act. Nat. Curios., 1828, p. 417. Rr2 308 OLIGOCHAETA Definition. Length, 2-5 mm. Ocsophagus as long as pharynx. Blood-vessels quite normal. Hab.— Europe. Vespovsky thinks that D’'UpEKEM’s Ch. miilleri (which the latter ought to have called ‘ vermicularis’—as he puts this name down as the only synonym) is identical with Ch. diastropha. It is to be distinguished, according to D’'UDEKEM, from Ch. limnaei only by fewer setae and absence of ‘spicules épidermiques.’ These latter processes (=tactile hairs) are figured by Vespovsky in Ch. diastrophus, so the identification is less certain. VAILLANT believes (p. 450) that D’'UpEKEm’s Ch. miillert is Ch. diaphanus; the difference in size may be, he thinks, a matter of age; but this does not seem likely, the difference being too great. VEJDOVSKY figures (24, PI. vi, fig. 12, chp) a small chitinous plate upon hinder median aspect of brain, the nature of which is mysterious. / Famity ENCHYTRAEIDAE, DEFINITION. Setae (absent in Anachacta) short, straight, or curved, not bifid at extremity. A single pair of calciferous glands sometimes present. Dorsal blood-vessel only present anteriorly, sometimes with cardiac body. Testes in XI, male pores on XII; a reduced spermiducal gland present; oviducts represented by pores. Spermathecae, one pair! in V generally opening into gut, with or without diverticula. Dorsal pores occasionally present. This family of Oligochaeta is very numerous’ in species, which are all of small size, ranging from a length of 3mm. to 4omm. The structure of the Enchytraeidae has been mainly elucidated by VEJDovsKY (8, 20), Eisen (18), and MicHAELSEN (1-5, 16); to a less degree by D’'UDEKEm (8), CLAPAREDE (3), and UDE (1, 2). MICHAELSEN has recently published a detailed ‘Synopsis’ of the family, the conclu- sions set forth in which are, in the main, adopted here. The family is a very natural one; there appear to be no forms transitional between the group and other Oligochaeta. This is satisfactory to the systematist, but it renders the labours of the naturalist who desires to study the inter-relationships of the different groups of Oligochaeta extremely difficult. All the Enchytraeidae have a prostomium; in most there is a single pore upon the prostomium; in a few forms (eg. in Fridericia gulba) there are also dorsal } Henlea puteana with two pairs is the only exception. DESCRIPTIONS OF GENERA AND SPECIES 309 pores; this family is the only one of the aquatic Oligochaeta which have dorsal pores. The setae are entirely absent in Anachaeta; there are only two bundles in Distichopus (if this genus be really an Enchytracid), but six in Chirodrilus (con- cerning which genus also more information is wanted); all the others have the usual four bundles of setae to a segment. The setae are either straight or bent in the prevalent /-shape; their extremities are never cleft. The setae in this family are always short and generally fairly numerous in each bundle. One genus only is entirely achaetous—the genus Anachaeta. The setae are here represented by large cells which depend into the body-cavity (see p. 5). The setae when present are of two kinds; there are curved sigmoid setae and straight setae; the former are found in certain genera, such as Puchydrilus; and the latter in other genera, such as Enchytraeus. The setae of a bundle are disposed in a fan-like fashion, the setae on one side of a bundle diverging from those upon the other side. The number of setae in a bundle varies from one (Enchytraeus monochaetus) or two (Fridericia bisetosa) to fourteen, which is the greatest number that has been hitherto recorded (in Pachydrilus minutus). Very commonly there is an inequality in number between the setae of the lateral and ventral bundles respectively; in this case, the lateral bundles have usually the fewest setae; thus in Pachydrilus pagen- stecheri there are 7-10 setae in the ventral bundles and 3-5 in the lateral. The setae of a given bundle are usually of a size; but this is not always the case; the most conspicuous exception is seen in the genus Fridericia; here the outer setae of a bundle are always larger than the inner, which are at the same time the younger. There are sometimes differences in size between the setae of the four bundles of a given segment; for example in Fridericia bulbosa the setae of the lateral bundles are smaller than those of the ventral. In Mesenchytraeus setosus there is something like a formation of genital setae; the lateral bundles of segments v—viii (inclusive) are made up of 1-4 setae, which are very much larger than those of adjacent segments. In Enchytraeus monochaetus the anterior setae are more slender than those of the posterior segments. Hnchytraeus monochaetus is unique in the group by reason of the fact that the setae are entirely wanting upon the first few segments of the body. The nephridia are peculiar in their form; they are stout and solid-looking organs, often lobed, with a lumen which (according to Botsius) forms a plexus in their interior. They frequently begin as far forward as the second segment, though they are wanting in those segments which contain the generative organs. Some Enchytraeidae are characterized by the possession of a single gland, or a pair of glands, which seem to be the equivalents of the calciferous glands of other worms (see p. 61). The family is also characterized by 310 OLIGOCHAETA the position of the reproductive organs; the testes are in the eleventh segment’; the ovaries in the following segment. The sperm-ducts open by a very reduced spermiducal gland on to the twelfth segment; the funnel of these ducts is peculiar in form, being generally extremely long and of a glandular appearance; the oviducts are represented merely by pores; or rather by a short prolongation of the septum which meets the pore; they seem to be degenerate. The spermathecae are far forward opening on to the intersegmental furrow iv/v; as a rule they open into the gut, a fact which is paralleled in the genus Sutroa, and was first discovered in the present family by MicHazLsEen (14). Egg-sacs and sperm-sacs are only present in Mesenchytraeus. The above characters distinguish the Enchytraeidae from all other Oligochaeta. MICHAELSEN allows twelve genera, of which two (not described by himself) must be considered doubtful; these genera are Chirodrilus and Distichopus; I shall recur to them presently. To these Bryodrilus of Ups (2), and Parenchytraeus of Hussz must be added. The genera which appear to be valid may be thus distinguished :— MESENCHYTRAEUS. Setae /-shaped; no dorsal pores, only a head-pore; origin of dorsal vessel postclitellian, contains a glandular body. STERCUTUS. Setae /-shaped; origin of dorsal vessel anteclitellian, contains a glandular body. PACHYDRILUS. Setae /-shaped; no dorsal pores ; blood coloured; dorsal vessel originates behind clitellum, contains no glandular body. BUCHHOLZIA. Setae /-shaped; dorsal pores absent; dorsal vessel originates from the tip of the single dorsal diverticulum of the gut; salivary glands present. HENLEA. Setae straight or /-shaped; origin of dorsal vessel anteclitellian ; no dorsal pores; oesophagus sharply marked off from intestine. ENCHYTRAEUS. Setae straight; dorsal vessel postclitellian in origin. FRIDERICIA. Setae straight; dorsal pores present; salivary glands present; dorsal vessel postclitellian in origin. ANACHAETA, No setae; no dorsal pores; dorsal vessel anteclitellian in origin; a single salivary gland; spermathecae not opening into gut. * In a few forms the testes, &c., are further forward. DESCRIPTIONS OF GENERA AND SPECIES 31i MARIONIA. Setae /-shaped; no dorsal pores and other characters as in Pachydrilus, except that testes are massive, not subdivided. BRYODRILUS. Setae /-shaped; no dorsal pores; dorsal vessel arising behind oesophageal glands in xii; blood colourless. PARENCHYTRAEUS. Setae straight; no dorsal pores; ventral vessel bifurcates only in first segment. The arrangement of the genera of this family naturally depends upon the affinities of the family as a whole to other Oligochaeta. Regarding, as I believe it to be necessary to do, the more simple forms as standing higher or lower in the scale (according to the sense attached to the words) than the more complexly-organized genera, in fact, as more specialized through degeneration, it appears to me that the genus Mesenchytraeus represents, on the whole, the most primitive Enchytraeid. I base this view of its position on the following characters :— (1) The setae are sigmoid in shape. (2) There are sperm-sacs and egg-sacs. On the other hand, the colourless blood, the absence of dorsal pores. and the rudimentary condition of the oesophageal glands (represented only by the cardiac body), furnish evidence against the placing of the genus. The genus Buchholzia exhibits two of these last characters with the addition of the sigmoid setae; it has, however, colourless blood like Mesenchytraeus. Pachydrilus has coloured blood and sigmoid setae. How are we to decide between the conflicting claims of these three forms ? A fourth, indeed, might be added, viz. Fridericita; this genus has dorsal pores, a character distinctive of the higher Oligochaeta. It seems to me that the importance of these several characters is indicated by their position in the following list :-— (1) Sperm-sacs and egg-sacs. (2) Ossophagea! glands real. Sigmoid setae (3) Red blood. (4) Dorsal pores. (1) Sperm-sacs are, with the exception of certain Enchytraeidae (the majority), present in alZ Oligochaeta, even in the lowly form Aeolosomu. They must evidently, therefore, be looked upon as being very distinctive characters of these Annelids. (2) Oesophageal glands are met with in none of the lower aquatic Oligochaeta, They are very common in the higher forms, excepting certain Enchytraeidae. Their presence or absence, therefore, occurring in nearly all the ‘earthworms.’ 312 OLIGOCHAETA seems to be correlated with the aquatic or terrestrial life. There are, it will be observed, no reasons for inferring that such is the case with the sperm-sacs, I have bracketed together, as being of equal importance, the presence of these glands and the sigmoid character of the setae. It is perfectly true that sigmoid setae are found in all genera of Oligochaeta, excepting only certain Enchytraeids; but the weight of this fact is partly lessened by the fact that among the aquatic forms there are very generally also capilliform setae, and the sigmoid setae are variously modified in shape (e.g. pectinate setae). (3) Red blood is only less universally present in the Oligochaeta than sigmoid setae. Apart from the Enchytraeidae, it stops short at the lower Naids, which have very faintly coloured blood; Aeolosoma has colourless blood. One can hardly help inferring from the facts that size is correlated with the cvlour of the blood; the minute Oligochaeta have ‘white’ blood, the larger and large forms red blood. Now the genus Pachydrilus contains some of the largest Enchytraeids (also, it must be admitted, some of the smallest). (4) There remains only the question of the dorsal pores; I am of opinion that these are distinctly related to the habit of the worm; they are to be found in no aquatic Oligochaeta. The genus Fridericia, in which alone they exist (among the Enchytraeidae), is terrestrial, and found in the driest localities; so also it is true of many Pachydrilus, &c. But, on the. whole, the group of the Enchytraeidae is, in the matter of its mode of life, in an undecided state; they are not purely terrestrial nor purely aquatic; and, if aquatic, neither definitely marine nor fresh water. The presence, then, of egg and sperm-sacs, coupled with the sigmoid setae, leads me to place the genus Mesenchytraeus in the position of the nearest approach to the original Enchytraeid. I do not, however, think that any other genus can be derived directly from Mesenchytraeus ; it is itself too degenerate in the matter of oesophageal glands and the colour of the blood. Nearest to it I should place Buchholzia, Pachydrilus, and Henlea, which have oesophageal glands, and Pachydrilus-like setae; and the two last will stand nearer to Mesenchytraeus than Pachydrilus, in which all trace of the oesophageal glands has disappeared. Fridericia and Enchytraeus will be still further remote from the primitive stock, and Anachaeta furthest of all. I do not feel able to make any suggestions concerning Distichopus and Chirodrilus, of whose anatomy we have at present insufficient knowledge. The following worms are either certainly or probably Enchytraeids. Halodrilus littoralis of Vurriti, thought by Vespovsky (24) to be a Tubificid. DESCRIPTIONS OF GENERA AND SPECIES 313 seems to have oesophageal glands as in Henlea. The setae, disposed in a fan-like manner, suggest an Enchytraeid, as also their small size. Lumbricus multispinus of Gruss (7) (called Echinodrilus multispinus by VATLLANT) seems to be an Enchytraeid, as VAILLANT (6, p. 89), has suggested. Lumbricus glacialis of Letpy (9), regarded by MicHaztsEn as belonging to this group, is said to possess generative organs extending from the fourth to the eighth segment. This does not read like an Enchytraeid. MICHAELSEN is, in my opinion, undoubtedly right in referring Enchytraeus moniliformis (D’UpEKEM), Nais albida (Carrer), Lumbricus jordani (Witu1aMs, 1), and Enchytraeus juliformis (KEssLER), to this family. He is less certainly right in doing the same with Saenuris abyssicola and 8. limicola of VERRILL, Tubifex pallidus (Ducks), and Saenwris vagans (JOHNSTON, 2). Enchytraeus sepultus of Menas, a fossil species from amber, is an undefined species. Lumbricus putridinis, synonymous, according to JouNnstToN (2), with Enchytraeus vermiculus, only needs to be referred to for the sake of completeness. The number of species in this family is considerable; the names that have been given to supposed species is greater still. One hundred and three names are quoted in MICcHAELSEN's Synopsis as applicable, or which have been applied, to worms belonging to this family. VAILLANT allows no less than seventy-two of these in a way; they are at any rate numbered and described in his work, though he doubtless casts some question upon the reality of certain among them. MICHAELSEN allows only sixty-one species (several of which are not included in VaILLANT's work, as they have been described since 1886); in addition to these sixty-one, he mentions twenty-nine which are partly ‘incertae sedis,’ partly ‘species inquirendae,’ and partly ‘species spuriae.’ To the first category are referred such species as can be defined specifically, but whose generic position is uncertain. To the second category are referred those species which are insufficiently characterised, but which may be subjected to renewed examination since the original types are extant, or since the description given is enough with the locality to ensure recognition should they be again met with. To the last category are referred a few species which are quite hopeless in these possibilities. Some of these species have been dealt with in the pages which follow; others may be suitably referred to here. The following five species are described by E1sENn (13) under the generic name of Archi- enchytraeus : — (1) Archienchytraeus tenellus. (2) 5 levinsenti. (3) i lampas. (4) ‘i gemmatus. (5) a ochraceus. MICHAELSEN says of these species that they are definable as species, but that it is uncertain whether they belong to the genus Henlea or Enchytraeus. I am not able to elucidate the matter any further, and therefore leave these species in the position in which MicHAELSEN placed them. About the following genera we require further information. Ss 314 OLIGOCHAETA Genus DISTICHOPUS, VERRILL. DEFINITION. ‘Form and colour as in Enchytraeus, with a well-produced girdle. Setapods in a single row on each side ventrally, in divergent fascicles of four in advance of the girdle and of three behind it.’ There is but one species in this genus which is regarded by MICHAELSEN as a, ‘species inquirenda,’ This species, called D. sylvestris, is 20-30 mm, in length and composed of sixty-eight segments. Genus CHIRODRILUS, VERRILL. DEFINITION. ‘Allied to Saenuris, but with six fan-shaped fascicles of setae upon each segment, two of which are ventral, two lateral, and two sub-dorsal; setae in the ventral and lateral fascicles four to nine, simple, acute, slender, curved like an italic /; those of the dorsal fascicles stouter and less curved, three to six in each fascicle. Intestine wide, somewhat moniliform. Anus terminal, large.’ I follow MICHAELSEN in assigning this genus to the family Enchytraeidae. Both VEJDOVSKY and VAILLANT place it among the Tubificidae. As MICHAELSEN has pointed out (5), the shape of the setae and the colourless blood together are inconsistent with any other view upon the systematic position of the two species which comprise the genus. The clitellum, too, is developed (in C. larviformis) upon the eleventh seta-bearing segment and upon a small part of the following segment, which is precisely what occurs in other Enchytraeids. The two species of the genus described by VERRILL are C. larviformis and C. abyssorum ; they were both dredged in Lake Superior. In C. abyssorum the dorsal-setae are described as being shorter than those of both lateral and ventral bundles. Both species are small, 6 or 8 mm. in length, with thirty-eight or forty-two segments-- vanother argument, not noticed by MicHAELSEN—for their being referred to the Enchytraeidae. * Genus MESENCHYTRAEUS, EIseEn. Syn. Analycus, LEVINSEN. Enchytraeus, VEJDOVSKY (in part.). Neoenchytraeus, EIseN (in part.). Pachydrilus, VAILLANT (in part.). DEFINITION. Setae /-shaped, usually more numerous in the ventral than in dorsal bundles of anterior segments. Head-pore usually near to anterior end of prostomium, no dorsal pores. Dorsal vessel arises behind clitellum, contains a cardiac gland, blood colourless. No salivary glands. Brain truncated or concave posteriorly, generally broader than long. Nephridia with short ante- septal and large irregularly lobate post-septal portion. Egg-sacs and sperm-sacs present ; sperm-ducts short, at most eight times as long as funnel. DESCRIPTIONS OF GENERA AND SPECIES 315 The term Mesenchytraeus was first applied by E1srn to a few species, which were grouped together as a subgenus of Enchytraeus. It was thus defined:—‘The spermatozoa, as long as they remain in the perivisceral cavity of the body, or in the vesicle of the efferent duct, are not free, but encysted or congregated into small globules surrounded by a membrane. The supra-oesophageal ganglion is deeply divided in front, but straight behind or nearly so, the emargination being very inconsiderable. The tube of the efferent duct is unusually short and broad, never more than six or eight times longer than the vesicle of the said organs.’ It will be observed that the two last of these characters are retained in MICHAELSEN’S definition, of which the above is substantially a reprint. As to the spermatozoa, MICHAELSEN does not use the point in his re-definition of the genus or in his revision of the Enchytraeidae (5). In an earlier paper, however, (upon 2-1 v ° ” M. tasmanianus. . . Ga xiii-xxii 8 rows v ° ” M. tuberculatus ei x xili-xviii ag v ° ” C. mediterreus . . 5 xiii-xvii 3 v x-xili T C.rubens . . . : 99 xiv-xvi 3 absent X-xiii a C. saccarius . eg ey xili-xvii 4-3>2-1 vor vi ix-xili a M. illawarrae. . . as xili-xxii 8 rows 2 ° single M. pygmaeus. . ‘ a xiv-xix 4-3>2-1 ? xii, xiii double C. mudgeanus . . 5 xili-xviii a v X-xili fF C. canaliculatus . . . 5 xiii-xviii 8 rows v x-xiii ” C. sloanet . ye = ? xi-xiii C. oxleyensis . : 9 xi-xili C. manifestus . .| complete xiv-xvii 3 v x-xili double C. unicus. . . incomplete xiv-xvii ‘9 vor vi xili-xv ‘4 C. fastigatus . . .| complete xiv-xvii 4-3>2-1 v ” C. tenuis . . ‘ fr ? ” C. mediocris 4 incomplete xiii-xvii ‘3 v ” C. illawarrae . i ” xiv-xvii "5 v 9 ” C.singularis . . . 53 xiii-xvili paired vi ° single C. gippslandicus . .| complete xiii-xvii paired ; v xiv, xv double irregular behind C. intermedius . | incomplete xiv—xviii paired ° single C. tanjilensis. . . .| complete xiii-xvii 4-3>2-1 v ° double C. frenchi . . . .| incomplete xiv-xvi ») irregular vi ° ” C. dubius . . . . .| complete xiv-xvii 4-3>2-1 v XV, Xvi io C. macedonensis . . .| incomplete < “a v o ” C. victoriae . . . «| complete xiv-xvi 5 v ° 7 C. willsiensis . . | incomplete xiv-xvii 3 v ° 9 C.narrensis . . ” xili-xviii 59 v 4 ” C.lucasi . 2 we 55 xilii-xviii 5 v 2 ” C. minor... ‘ 35 Vv ° single M.cameroni. . . . 7 v/vi double M. insignis . . ‘ ‘is xiii-xviii 5 vi xv, xvii single M. hulmet . és ‘ 33 xiii-xx 5 v 5 M. obscurus - AG xiii-xix "7 vi ° double M.mannti. . 1. . ‘i Xiv-xviii “3 v/vi o ” M. victoriensis ‘ 50 », irregular v 2 ” M.incertus . complete xili-xvili “ vi a ” M. sinuosus . . | incomplete or v o ” M. roseus. . complete xiii-xviii ‘ v Xv, Xvi i M. attenuatus . | incomplete xiii-xviii js v o ” C. simulans . . “ 55 Vv Xiv, XV 3s C. seminctus . . : o xiii-xvii 8 rows v ix-xili single C.insularis .. . | incomplete 2 ° ? double DESCRIPTIONS OF GENERA AND SPECIES 449 say ireoge oe SPERMATHECAE. a, NEPHRIDIA, ees lobate ° viii, ix; one small div. xiii diffuse + ” ° 2 ” ” ” #5 + ” 20 viii, ix ; two or three diy. xii a + tubular ° viii, ix ; notched div. xiii 4 + 5 ° v-ix no div. i paired + ” ay xii ” + lobate + vii-ix ; div. xiii » (alt.) + tubular + ? xii paired ° 2 ? viii-ix ; div. xili diffuse + is + 6 xii diffuse + paired + ? ? . ’ diffuse + 2 ° sa xiii $5 of ? ? vii-ix ; two div. paired (alt.) + three pairs ” vi-ix; div. + ? 5 xii rs 4: 2 v-ix; div. 43 paired a two pairs viii, ix; div. xii or xiii three pairs + tubular two pairs ” ? lobate viii, ix; div. xii ” * ° viii, ix ; two div. ” diffuse + viii, ix ; div. ” ” + tubular v-ix; div. i paired + tubular ° viii, ix; one div. xiii ” + 55 ° y-ix ; one div. xii ” g ” ° v-ix ” ” - 4 viii, ix ; two div. three pairs + (double) tubular vi-ix ; one div. paired 35 v-ix ; one diy. ” ” + ? v-ix ; two div. ” ” tubular viii, ix; div. ” ” ” ” a ” ef ” ” ” oe te lobate v-ix ; div. xiii diffuse + o viii, ix; div. ” ” + ” ” ” a m 5 viii, ix ” ” + tubular vii, ix xii paired + lobate viii, ix xiii diffuse + tubular os xii paired = xiii diffuse 7 - xii paired ap ” ” ” aa + 9 Pi #3 diffuse + tubular ” ” P aired t+ ° viii, ix; without div. commence in xiii ” 3M 450 OLIGOCHAETA A careful tabulation of FLETCHER’s results (from above table) does not perhaps altogether support this proposed division of the genera; but in only a few cases has he noted the form of the spermiducal glands, which is, I believe, of systematic importance. Out of the twenty-three species to which he .has paid attention, five conform to the rule of association which I have endeavoured to lay down above; four are apparently exceptions; of these four C. rusticus has diffuse nephridia, lobate glands, but the last pair of hearts are in xii; I have already referred to M. gippslandicus as another exception resembling M. australis; M. tasmanianus has paired nephridia and tubular glands, but the last pair of hearts are in xiii; C. mediterreus has paired nephridia with lobate glands, the last pair of hearts in xiii; of the remaining species, three are peculiar in having three pairs of nephridia per segment like one of the species described by SpENcER; so I put them out of the comparison, reserving a distinct generic title for them. There remain eleven species which are not sufficiently described by FLeTcHEer; in nine of them the condition of the nephridia and the segment occupied by the last pair of hearts is noted; five of these agree with the proposed division; C. fletcheri, described by myself, has paired nephridia with lobate spermiducal glands. On the whole, therefore, it seems to me to be justifiable to retain the two generic names Cryptodrilus and Megascolides, but to sort the species rather differently. I put those with tubular glands on one side, reserving the name Megascolides for them; the species with lobate glands I call Cryptodrilus. In addition to these there remain a number of Australian species which FLETCHER has relegated to three genera—Digaster, Perissogaster, and Didymogaster; the name of the latter must in any case, as FLETCHER has pointed out, be dropped since it has been already applied to a genus of insects. These three genera contain between them only seven species; in the following table the chief characters of these seven species are set forth. PROSTOMIUM. | CLITELLUM, SETAE, aizzann,, | CUO EBOUS eee 7 : . 4 GLANDS. NEPHRIDIA. Digaster armifera . ‘ . | incomplete | xiii-xviii | paired, ventral | 2 in v, vi o + closer Perissogaster nemoralis . . . sy xiii-xviii *5 3% 3 in v-vii X-xiv + Perissogaster queenslandica. . 3 2 ” < ” Xiv, XV Digaster perrieri 5 xiv—xvii ” 5 2 inv, vi ° + Digaster lumbricoides. . : xiv-xvi paired Perissogaster excarata - xili-xviii | paired, ventral | 3 in v-vii ° closer Didymogaster sylvaticus . sh xiii -xviii 7 95 2 in vi, vii ° DESCRIPTIONS OF GENERA AND SPECIES 451 It will be noted from the above table that all these Species agree in a number of important characters; they have all lobate spermiducal glands, diffuse nephridia, more than one gizzard, a clitellum of about the same extent, and two pairs of spermathecae; D. sylvaticus, and Perissogaster are peculiar in the spiral intestine ; as, however, this peculiarity also occurs in Plugiochaeta, it is perhaps to be regarded as of less weight for systematic purposes in the present group. Penial setae are either present or absent; but their presence or absence does not appear to coincide with other differences. Considering that all these species are confined to Australia, it seems hardly necessary to separate them, as FLETCHER has done, into so many as three genera. I may be blamed for allowing them collectively generic distinction from Cryptodrilus, with which they agree in the lobate spermiducal glands and diffuse nephridia; as it is, I propose to place them all in one genus, which will, therefore, retain the name of Digaster. This genus will be distinguished from Cryptodrilus by the presence of two or three gizzards; this is the only positive difference. MICHAELSEN (18, iv) has proposed to create a genus Fletcherodrilus for FLETCHER’S C. wnicus; in the same species he places FLETCHER’s C. fasciatus, and his own C. purpureus, and C. pelewensis, considering them to be nothing more than varieties. The ‘genus’ is thus defined by MtcHAELSEN :—‘Borsten in 8 weit getrennten Reihen ; Offnung der Prostatadriisen (auf dem 18. Segment gelegen) median und unpaarig ; ebenso die Offnungen der Samentaschen; Giirtel nicht iiber die Offaung der Prosta- tadriisen nach hinten hinausragend, ringférmig geschlossen; Darm mit einem einzigen Muskelmagen vor und mit Kalkdriisen hinter den Hodensegmenten; je ein Paar grosser Segmentalorgane in den einzelnen Segmenten (ausmiindend in den Borsten- linien iv); Lagerung der Geschlechtsorgane normal; ein Paar schlauchformiger Pro- statadriisen (im 18. Segment); Penialborsten nicht vorhanden.’ SPERMIDUCAL| PENIAL LAST “SACS. RMATHECAE, DORSAL PORES. NEPHRIDIA. | HABITAT. SELES GLANDS. seraz, | *?* HEART. ix, xii lobate + viii, ix from xii/xiv xii diffuse Australia ix, xi, xii i + 9 from x/xi xiii 5 ss xi, xiii [2] 5 ° a from iii/iv xii i ; ai xi, xii i + 3 from x/xi $5 a5 ” o [?] from iv/v ” ” ix, xii a ? ¥5 none, or only at pos-| xii $3 7 terior end of body. ix, xii 5 ? vii-ix from v/vi re 5 3M2 452 OLIGOCHAETA The principal characteristic of the genus is, of course, the fusion into a single median series of the spermathecae. About the same time I had myself suggested the desirability of separating MICHAELSEN’s OC. purpureus into a distinct genus. Previously to both of us FLeTcHER had also surmised that it might ultimately be necessary to take this step. ‘These three species,’ he remarks, ‘form a group of closely allied forms whose claims to be regarded as worthy of generic separation will be considered hereafter.’ I shall here adopt the generic name of Fletcherodrilus for the species of Cryptodrilus with median spermathecae and male pore. There can be no doubt, I think, of the validity of my genus Millsonia, from Western Tropical Africa, unless indeed it should include the African Dichogaster. Another genus of which the exact position is perhaps a matter of doubt is Plutellus; this was originally described by PERRIER twenty years ago. More recently BENHAM has met with what he believes to be a second species of the genus, and has suggested that there may be some errors in PERRIER’S account of Plutellus heteroporus; there is no doubt that if PERRIER’s description is accurate in every particular the species named by him P. heteroporus is not congeneric with Benuam’s P. perrieri ; accepting BeNHAm’s corrections as probable, it is not an easy matter to distinguish Plutellus from Megascolides. I abstract from Bennam’s list of the chief characters of the genus the following :— (1) Setae in eight rows. (2) Clitellum complete, xiii-xviii. (3) Male pores on xviii. (4) Nephridiopores alternate. (5) Testes in x; sperm-sacs in xi; spermiducal glands tubular. (6) Spermathecae, four pairs without diverticulum. (7) No caleiferous glands. P. heteroporus differs in (6) and (7); there are three pairs of calciferous glands, and the spermathecae have a diverticulum. The above enumeration of the chief characters of Plutellus does not permit of a very distinct separation from Megascolides. Indeed, there is no character that is quite decisive in the matter. I do not, therefore, see my way to accepting the genus Plutellus at all, that is to say as amended by Brenuam; it may be that PeRRIER’s original description may prove to be more accurate than it has been supposed to be; in this case the genus Plutellus will stand. DESCRIPTIONS OF GENERA AND SPECIES 453 I shall now consider a group of Cryptodrilidae which have been referred to four distinct genera, and which should, as I think, be included in one group ; I refer to Ocnerodrilus (including Pygmaeodrilus), Nannodrilus, and Gordiodrilus. These genera agree with each other, and differ from most earthworms (I shall mention an exception presently) in the following characters :— (1) The calciferous glands, paired or single, lie in the ninth segment. (2) The spermiducal glands are lined by a single layer of cells only. Besides these points of resemblance, there are other agreements in various characters, which, though not unknown in other worms, mean something, perhaps, collectively. Such are :— Absence of penial setae; small size; commencement of intestine in twelfth or fourteenth segment; absence of typhlosole; paired nephridia; last pair of hearts in eleventh segment; setae strictly paired. Even if we take the most characteristic form, and one only of each of these genera, it is difficult to show contrasts that would be regarded as sufficiently marked to permit of so wide a separation as EIsen (1, 4) would institute, except perhaps in the case of Gordiodrilus tenwis, of which more presently. For instance, let us compare Gordiodrilus elegans, Ocnerodrilus eiseni, and Nannodrilus africanus. CALCIFEROUS | SPERMIDUCAL| ..pRMATHECAE. SPERM-DUCT. GLANDS. GLANDS. Gordiodrilus . unpaired two pairs two pairs ; opens separately rudimentary diverticula Ocnerodrilus . paired one pair one pair; no opens with spermiducal gland diverticula Nannodrilus . .| unpaired two pairs one pair; no opens with one spermiducal diverticula gland into bursa copulatrix Slender though these differences are, yet they must be held to be of sufficient Too much stress cannot be laid upon Although, among importance to allow of generic separation. the presence or absence of diverticula to the spermathecae. earthworms, diverticula are very constantly either present or absent in a family, let alone a genus, there are several instances where a genus has or has not, according to the species, diverticula appended to the spermathecae. But, nevertheless, we cannot but allow that G. matthewst and G. elegans belong to the same genus, though one (G. elegans) has not, and the other has, at least traces of*a pair of diverticula appended 454 OLIGOCHAETA to the spermathecae. Again, the presence of two pairs of spermiducal glands, so characteristic of Gordiodrilus, is not universal in that genus; for G. ditheca, in other respects extremely near to G. elegans, has but one pair of these structures ; and, as I point out elsewhere (below), there are no reasons for regarding this species as having been described from individuals that were, in this particular, immature. The median unpaired calciferous gland of the typical Gordiodrilus is distinctly paired in G. robustus ; nor is it permissible to found generic distinctions upon the paired or unpaired condition of an organ which a more profound study of the Oligochaeta shows to be an impossibility. The fact that in all the species of Gordiodrilus the sperm-ducts open quite independently of the spermiducal glands would be a slender basis for distinguishing two genera; and, moreover, we are relieved from all temptation to lay stress upon this character by the existence of different species of Ocnerodrilus in which the sperm-ducts are, and are not, separate up to their very opening from the spermiducal glands. But, in spite of these undoubtedly close resemblances, I prefer to keep the genera separate, on account of the different segment on which the sperm-duct opens, and its distinctness from the spermiducal gland. There is a question whether G. tenuis is really congeneric with the other forms; unfortunately I was not able to give anything like a complete account of the anatomy of this species (29). In the meantime its differences from the other worms are not insignificant. In the first place the transference of the male genital pores so far back is a not unimportant character; it is true that such a variation in the position of these pores is found in species undoubtedly belonging to the same genus; Buchholzia is an instance to the point; but with the present worm there are other differences; the testes are but a single pajr, and the enlarged ventral setae are another peculiarity; so also is the great extent of the clitellum. The presence of calciferous glands in the ninth segment, and the structure of the spermiducal glands is not absolutely distinctive of the genera Gordiodrilus, Nannodrilus, and Ocnerodrilus ; the family Acanthodrilidae contains a genus, Kerria, represented by two species, which shows a perfectly similar character; the calciferous glands are in the ninth segment, and the spermiducal glands are lined by a single layer of epithelium. In possessing no penial setae this genus differs from the vast majority of Acanthodrilidae; but this is not unknown in the family, for in the genera Benhamia, and Acanthodrilus, there are species without penial setae. In spite of the resemblances between Ocnerodrilus and Kerria, I think that it is necessary, in the present state of our knowledge, to place them in different families, though the existence of these forms shows how difficult it is to distinguish the two families, Cryptodrilidae and Acanthodrilidae; at present the Acanthodrilidae differ from all DESCRIPTIONS OF GENERA AND SPECIES 455 Cryptodrilidae, including the two genera here treated of, in the fact that the two pairs of spermiducal glands lie not in successive segments, but are separated by a segment which bears the apertures of the sperm-ducts. It is very possible, however, that this genus, Kerria, is a stage in the development of the genus Ocnerodrilus out of Acanthodrilus, or it may be that the resemblance is due to a convergence caused by a simplification in structure; in this case it might be said that the likeness between Ocnerodrilus and Gordiodrilus is something of the same kind; but here the resemblance is rather closer; indeed, the only difference between the two genera is that the structure of the calciferous glands is a little different, and that the male pore opens upon a different segment, independently also of spermiducal glands. Besides the genera just referred to which appear to be simpler in structure than the more typical forms, there are three other genera not nearly related to those just described, but also showing some evidence of degeneration; these are Pontodrilus, Photodrilus, and Microscolex; the latter, however, is not quite so simplified as are the first two genera. They are all three of small size; there is often no gizzard, or merely traces of a gizzard; there are sometimes no dorsal pores; the nephridia do not commence until the fourteenth or the fifteenth segment, except in Microscolex, where they begin earlier, and they are paired structures; the subnervian vessel is absent; there is no typhlosole. In these particulars the three genera appear to be somewhat degenerate as compared with other Cryptodrilidae, though not so much so as are the genera Gordiodrilus and Ocnerodrilus; in this case, as in that, smallness of size accom- panies simplification of structure. The following table indicates the mutual relationships of the three :— MICROSCOLEX. PONTODRILUS. PHOTODRILUS, Setae . F Fit in eight rows, or paired in eight rows in eight rows Male pores . . . . xvii xviii xviii Nephridia. . . . . begin in ii-v begin in xv begin in xiv Gizzard . . . . .| present, rudimentary, or absent | rudimentary absent Calciferous glands. . absent absent 45 Last heart . ey in xii in xiii in xii Spermathecae . ‘i one pair two pairs one pair Spermiducal glands . tubular tubular tubular 456 OLIGOCHAETA It will be obvious from the above table that Photodrilus and Pontodrilus are nearer to each other than either of them is to Microscolex. So near does this resemblance appear to me to be, that I think it is desirable to unite the two genera into one, which must obviously bear the name of Pontodrilus. The only point of importance which divides this genus from Microscolex is the position in the latter The nearly invariable presence in Microscolex of penial setae distinguishes it from the of the male pores upon the seventeenth instead of the eighteenth segment. two remaining forms, which I unite here into a single genus. In the following table the principal characters of the genera of Cryptodrilidae are placed side by side for comparison :— LAST CALCIFEROUS SPERMIDUCAL PENIAL ; i PORE. HABITAT. NEPHRIDIA GIZZARD. eae cLanps, | MALE POR GnaANDS: SETAE. Gordiodrilus . paired + oro xi ix xviii or xx Xvii-xix, ° Africa ; W. Indies tubular Ocnerodrilus . i ° xi ix xvii xvii, tubular ° America and Africa Nannodrilus . 95 rudimentary xi ix xvili xvii, xviii, Africa tubular Microscolex 5 + oro, or xii ° xvii xvii, tubular | present | Europe ; America; rudimentary (rarely 0)| New Zealand ; Teneriffe Pontodrilus 9 rudimentary] xii ° xvili xviii, tubular ° Europe ; W. Indies; E. Indies Typhaeus . diffuse xiii xii or xiii xvii xvii, tubular | present India Dichogaster os 2 ? xiv (xv)-xvi xvii xvii, tubular | present Africa ; Fiji (xvii) oro Deodrilus . re + ? xv-xvii xviii xviii, lobate + Ceylon Fletcherodrilus | paired + xii xili-xv | xviii xviii, tubular ° Australia Trinephrus .| three pairs + xii X (xi)-xiii xviii xviii, lobate | + oro $3 or tubular Digaster diffuse 20r3 xii or | x-xiv or xiv, xviii xviii, lobate | + oro i xiii xv Megascolides .| diffuse or + xii or x-xiii or xviii xviii, tubular ° Australia, New paired xiii more Zealand, America Cryptodrilus diffuse or + xii or x-xiii or xviii xviii, lobate | + oro Australia paired xiii | xiv—xvi, &e. Microdrilus .| diffuse 2 Xv-Xxvii xvii Xvii, tubular Java, Penang Millsonia . + 2 xiii xXv-Xviii {xvii (paired| xvii, tubular ° W. Africa or single) DESCRIPTIONS OF GENERA AND SPECIES 457 Affinities of Cryptodrilidae. This family has perhaps the most intimate relations! with the Perichaetidae; the genus Megascolex forms an almost ideal link; the fact that in the Perichaetidae there are invariably more than eight setae per segment, is really the only dis- tinguishing mark which enable them to be differentiated from the Cryptodrilidae ; and it will be remembered that in the genus Megascolex the anterior segments may have only eight setae apiece, while further back the setae become numerous. This genus might with equal reason be assigned to either of the two families Perichaetidae or Cryptodrilidae. It is not too much to say that there is hardly a single point of structure in the Cryptodrilidae which is not also characteristic of the Perichaetidae, and vice versa, that is to say of some one or more Perichaetous worms or Cryptodrilids. At first sight there may be some objection to this statement. Many Cryptodrilids have two gizzards, or even three; while, with the exception of Pleionoguster, no Perichaeta (in the wide sense) has more than a single gizzard; and the gizzards of Pleionogaster being at the posterior end of the oesophagus rather recall the similarly placed gizzards of the Eudrilids, Hyperiodrilus and Heliodrilus, than Dichogaster or Digaster. The genus Perichaeta, however (in the strict sense), has a gizzard which occupies certainly two, if not three segments; where there are two gizzards in the Cryptodrilidae they lie in consecutive segments; now there is not a wide interval between the two kinds of modification; and I should be disposed to compare the single gizzard of Perichaeta occupying two to two separate gizzards in a Cryptodrild occupying two consecutive segments, rather than to compare it with the single gizzard of such a form as Eudrilus or Acanthodrilus. With other families of Oligochaeta there are not such plain relationships. The Acanthodrilidae, for example, are separated by certain well-marked characters from all Cryptodrilidae. MicHAELSEN (10) has certainly compared Dichogaster with Benhamia, giving a tabular statement of the points of similarity and difference; although these resem- blances are undoubtedly numerous and siriking, there is one difference which absolutely distinguishes all Cryptodrilidae from all Acanthodrilids; in every Acan- thodrilid the male pores open on to the eighteenth segment; and the spermiducal 1 The intimate relationship which exists between all the families of the Megascolicidae is, perhaps, exemplified by the genus Microscolex of S. America and its affinities to the Acanthodrilus of that continent, and by the Cryptodrilids and Perichaetids of Australia. The sperm-sacs of the American Microscoler and Acanthodrilus are frequently in segments ix, xi, or in xi only—an unusual position. Those of the Australian worms are often in segments ix, xii, also an unusual position. 3N 458 OLIGOCHAETA glands open on to the segment in front of and the segment behind this, or if there is but one pair, as in the species Acanthodrilus monocystis alone, they open on to the seventeenth segment; in the Cryptodrilidae, on the other hand, the termination of the sperm-ducts may be independent of that of the spermiducal glands, but if this is the case the two pores are nearly always situated upon the same segment?. Gordiodrilus does not form an exception to this statement; it is true that here the sperm-duct-pore is independent of that of the spermiducal glands of which there are two pairs opening on to consecutive segments; but one of these opens on to the same segment as that which bears the sperm-duct-pores, whereas in Acanthodrilus the sperm-duct-pore is never upon the same segment as that of the spermiducal glands. Apart, however, from this difference it would be difficult to draw a sharp line of demarcation between the Cryptodrilidae and the Acanthodrilidae. There are no other structural peculiarities in which either family is totally differentiated from the other. I am disposed to agree with MICHAELSEN in considering that Dichogaster is one of the genera which is nearest akin to the genus Benhamia. It will be remembered that in the type-species of the former genus— Dichogaster damonis— there are three pairs of tubular glands of which the two posterior opening on to the eighteenth and nineteenth segments are the smaller, and the anterior pair in common with which open the sperm-ducts dare distinctly the larger; if we suppose the middle pair of these to disappear, and the sperm-ducts to be continued on to the eighteenth segment we should have an Acanthodrilid at once. Another point of resemblance to the Acanthodrilidae is to be seen in Microdrilus saliens and in Ocnerodrilus; in the former worm the buccal cavity has, as I have mentioned in my account of the anatomy of this species, a diverticulum, which is of a different structure to the alimentary tract of which it is a diverticulum; the cells are more glandular and stain but feebly in carmine; Micnarnsen, Horst, and I myself have described in various species of Benhamia a perfectly similar diverti- culum; the description which Horst has given of this diverticulum of the buccal cavity in the species Benhamia malayana (17, p. 36), which I have already referred to in considering the anatomy of the alimentary canal in the Oligochaeta, shows its identity with that which I have seen in M. saliens; as a matter of fact, however, I have had the opportunity of comparing the structure in question for myself in B. crassa, and can, therefore, certify to its exact similarity ; in both Microdrilus, and in, at any rate, one species of Benhamia: ie. that which has only just been mentioned, the end of the sperm-duct, near to its external pore, is enveloped in a thick layer of muscular fibres; the same thing ! Microscolex modestus is an exception. DESCRIPTIONS OF GENERA AND SPECIES 459 occurs in three or four species of the Ocnerodrilus. Microdrilus shows further resemblances to Benhamia in having two gizzards in immediately consecutive segments, and three pair of calciferous glands which seem to occupy the very same segments as in Benhamia; so also do those of Millsonia, the penial setae are practically indistinguishable from those of B. crassa; indeed, M. saliens only differs from that species of Benhanvia, in the fact, that there is but a single pair of spermiducal glands, and that the sperm-duct, though it opens independently of the gland, is close to it on the same segment instead of being a segment in front; a difference of perhaps some importance is the fact that in Microdrilus the calciferous glands are arranged as they are in Lumbricus, i.e. they do not all communicate directly with the gut. As one undoubted Acanthodrilus (A. monocystis) has only a single pair of spermiducal glands, the line of demarcation between the Acantho- drilidae and the Cryptodrilidae becomes a very thin line. Genus MICROSCOLEX, Rosa. Syn. Deltania, EIsEn. Cryptodrilus, MIcHAELSEN (in part.). Rhododrilus, BEDDARD. DEFINITION, Setae strictly paired or distant; prostomium complete or incom- plete; clitellum XIII (XIV)-XVI (XVII). WNephridia paired commencing in II-V. Gizzard present or absent; no calciferous glands. Spermathecae nearly always present, and, if so, with diverticulum. Spermiducal glands tubular with penial setae; male pores (on XVII, rarely XVIII) often separate from spermiducal gland pores. This genus was founded by Rosa (17), who described a single species from Italy under the name of M. modestus. Later, the same author added Fiercuer’s ‘ Fudrilus dubius’ to the genus, having met with that species and with M. modestus in the Argentine. A third species of the genus, as I define it in the present work, is a worm which I (87) originally referred to a distinct genus Rhododrilus. That genus was defined as follows:—‘Setae in eight rows. Clitellum occupying segments Xiv-xVli ; atria tubular ; penial setae present ; vasa deferentia opening on to the exterior in the same segment (xvii), but independently of atria; gizzard present.’ The foundation of this new genus was, I think, justifiable at the time. But it cannot be any longer retained. The principal point of difference from M2croscolex was (supposed to be) the separate orifices of the sperm-ducts and the spermiducal 3N2 460 OLIGOCHAETA glands. We now know that precisely the same separation occurs in M. modestus. It is not, therefore, requisite to do more than merely mention the fact that E1sEn (16), in ignorance of the condition obtaining in M. modestus, resuscitated my genus Rhododrilus. The last-mentioned authority has founded a third genus Deltania. This genus, which contains three species from California, is distinguished from Microscolez by the fact that the ventral setae in the neighbourhood of the male pores converge towards each other. This condition had been before described in other species of Microscolex, which E:sen accordingly referred to Deltania. Since EIsEN proposed this division nine new species of the genus have been studied by myself from South America. If it is necessary to subdivide Microscolex, these new species perhaps offer rather better characters. All of them differ from M. modestus, &c., in having but a single pair of male gonads instead of two pairs. As some have strictly paired setae instead of the eight rows formerly considered distinctive of both Microscolex and Deltania, the approximation of the ventral setae to each other on some of the genital segments loses its importance. Were these species the only species of the genus to be found in South America I should be inclined to regard the single testes and sperm-ducts to be a structural character requiring recognition by generic separation. As, however, both M. dubius and M. modestus appear to be indigenous inhabitants of the same part of the world this division seems to be less necessary. As it is unaccompanied by any other character which is equally distinctive, I prefer to leave the genus Microscolex undivided. The genus is quite easily definable as will be seen from the above definition. The eighteen species are of very varied sizes; at one extreme we have MicHAEtsen’s ‘Cryptodrilus spatulifer, which I cannot separate from the genus. At the other extreme there are specimens of M. modestus, only 16mm. long, and these are among the smallest of earthworms. The head-quarters of the genus is evidently in America, where fourteen of the species occur; of these only two, viz. M. modestus and M. dubius, occur outside this region. Nine are absolutely confined to South America, to the more temperate regions of that continent. The following is a list of the species :— (1) M. modestus, Rosa, Italy; Argentine. (2) M. dubius (FLETCHER), Australia; Argentine. (3) M. algeriensis, F. E. B., Algeria. - (4) M. poultoni, F. E. B., Teneriffe. (5) M. minutus, F. E. B., New Zealand. (6) M. novae-zelandiae, F, E. B., New Zealand. (7) M. spatulifer (Micx.), South America. DESCRIPTIONS OF GENERA AND SPECIES 461 (8) M. griseus, F. E. B., South America. (9) M. robustus, F. E. B., South America. (10) M. michaelseni, F. E. B., South America. . (11) M. papillosus, F. E. B., South America, (12) M. gracilis, F. E. B., South America, (13) M. corralensis, F. E. B., South America. (14) M. diversicolor, F. E. B., South America. (15) M. longiseta, F. E. B, South America. (16) M. elegans (Etsy), California. (17) M. troyeri (E1szn), California. (18) M. benhami (EisEwn), California. (19) M. monticola, F. E. B., New Zealand. (1) Microscolex modestus, Rosa. M. modestus, Rosa, Boll. Mus. Zool. Torino, vol. ii, 1887, No. 19. Definition. Length, 35-60 mm.,; number of segments, about 75. Setae in eight rows. Nephridia commence in segment IV. Gizzard rudimentary. Spermathecae one pair with a small diverticulum, Penial setae present. Testes in X, XI. Sperm-ducts open on segment behind spermiducal glands. Hab.—Argentina; Patagonia; Italy (2). The discovery of this species in the Argentine [Rosa, 6] renders it possible that Jtaly is not its true habitat; as a matter of fact there is a considerable traffic between Genoa (in the neighbourhood of which the worm was first found) and the Argentine Republic—particularly in the way of emigrants. In addition to the points mentioned above this species differs from the closely-allied WM. dubius in the white clitellum (instead of orange-coloured); it is morever, according to Captain Spegazzini, phos- phorescent. Rosa has pointed out that in this case it is no longer possible to be certain that the ‘Lumbricus phosphoreus’ of Duaks is really identical with Photo- drilus ; it may well be the present species. (2) Microscolex dubius (FLETCHER). Eudrilus (?) dubius, FLETCHER, Proc. Linn. Soc. N.S. W., vol. ii (2), 1887, p. 378. M. dubius, Rosa, Ann. Mus. Civ. Genova, vol. ix (2a), 1889, p, 511. Definition. Length, 50-70 mm.; number of segments, 110-120. Setae im eight rows, ventral converging on genital segments. Nephridia commence in segment V. Gizzard absent. Spermathecae absent. Sperm-ducts join spermiducal glands about half way 462 OLIGOCHAETA along the muscular tube of the latter ; penial setae present. Testes in X, XT Hab.— Argentina ; Australia (2). This appears to be a very common worm in the Argentine; a large collection of earthworms, which I received from the neighbourhood of Monte Video through the kindness of Mr. Chamberlain, consisted almost entirely of this species. So did the bulk of the specimens collected near Buenos Ayres by Dr. Micuarxsen. It is unin- telligible why FLETCHER should have at first referred it to the genus Hudrilus, for he correctly states the many and important points in which it differs from that genus. (3) Microscolex algeriensis, Bepparp. M. algeriensis, BEDDARD, P. Z. S., 1892, p. 29. Definition. Length, 30 mm.; number of segments, about go. Setae in eight rows, Nephridia commence in segment IT. Gizzard absent. Spermathecae one pair, with a small diverti- culum, Sperm-ducts unite and traverse a part of the thickness of body wall before joining duct of spermiducal gland. No penial setae. Testes in X, XI. Hab.—Algeria. This is the only species of the genus which is without penial setae. On the seventeenth segment the ventral setae are quite normal, the male pore lying on each side just to the outside of the ventralmost setae. The absence of penial setae is, of course, a point of resemblance to the closely-allied Pontodrilus, which is not shared by the other species of the genus. The brain lies in the second segment, whereas in the species next to be described it is in the more usual position, viz. in segment iii. (4) Microscolex poultoni, BEDDARD. M. Poultoni, BEDDARD, loc. cit., p. 32. Definition. Length, about 30 mm. Setae in eight rows, ventral converging on genital segments. Nephridia commence in segment II. Gizzard absent. No spermathecae ; testes in X, XI. Sperm-ducts, after uniting together, pierce the body-wall and unite with the spermiducal gland just at its opening on to the eaterior, Penial setae present. Hab.— Madeira. I have figured the penial setae of this species (38, fig. 2, p. 34), which are quite unornamented. There are no figures of the penial setae of the two other species which possess penial setae; but it appears from the descriptions that their form is not at all different from those of the present species. The first nephridiopore lies, as mentioned in the above definition of the species, on the second segment, but the nephridium itself chiefly lies in the following segment, i.e. the third. This extension DESCRIPTIONS OF GENERA AND SPECIES 463 backwards of the nephridium is rendered possible by the absence of the septa in this region of the body, which do not commence until the fifth segment (v/vi); M. algeriensis agrees with the present species in both these points. (5) Microscolex minutus, Bepparp. Rhododrilus minutus, BepDARD, P. Z. 8., 1889, p. 381. Definition. Length, 3 in. Clitellum, XIV-XVII. Setae of ventral couples closer together than of outer anteriorly ; posteriorly both equidistant. Dorsal pores present after clitellum. Gizzard in segment V. Septa dividing segments VI/XII specially thickened. Spermathecae four pairs in VI-IX, Penial setae present. Sperm-ducts open independently of glands. Hab.—New Zealand. This species is peculiar in possessing four pairs of spermathecae. In this it approaches the more highly organized Cryptodrilids, particularly the genus Mega- scolides. The diverticula are very nearly as large as are the spermathecae themselves ; both are tubular in form. The spermiducal glands extend through seven segments. (6) Microscolex novae-zelandiae, Bepparp. M. novae-zelandiae, BeDDARD, P. R. Phys. Soc., 1893, p. 33. Definition, Length, 42 mm. ; diameter, 2mm. ; number of segments, 76. Clitellum, XIII-XVIL. complete except in XVII, where are paired male pores. Setae paired, but not very closely. Nephridia commence in II. Gizzard very rudimentary in V ; intestine begins in XVI. Septa separating segments VIII/XIII slightly thicker than the rest. Penial setae without ornamentation. Spermathecae in IX with two diverticula. Hab—New Zealand. This species has three papillae in neighbourhood of male pores, one in front and two just behind apertures arranged so as to form a triangle. (7) Microscolex spatulifer (MicHAzLsEy). Cryptodrilus (?) spatulifer, MICHAELSEN, JB. Hamb. wiss. Anst., vi, 1889, p. Io. Cryptodrilus spatulifer, BEDDARD, P. R. Phys. Soc., 1893, p. 31. Definition. Length, 145 mm.; number of segments, 146. Prostomium complete. Setae strictly paired. Clitellum, XILI-XVII. Gizzard in VI; intestine begins in XVII. Gonads one pair only; sperm-sacs in XI; spermathecae in IX, with large caecum ; racemose at distal end. Penial setae with crenate ridges. Hab.—Chili. 464 OLIGOCHAETA My account of its anatomy substantially bears out that given by MICHAELSEN, excepting only as regards the form of the prostomium. I found it to completely divide the buccal ring. The colour of the spirit specimens of this species is a dark purple red dorsally. The penial setae are ornamented by serrated ridges at the free extremity. (8) Microscolex griseus (NEW SPECIES). Definition. Length, 84 mm.; diameter, 5 mm.; number of segments, 117. Setae strictly paired. Dorsal pores present. Prostomium complete. Clitellum, XIII-XVII. Gizzard in VI. Sperm-sacs in IX, XI. Testes in X. Spermathecae in IX, with large stalked diverticulum. Penial setae with spinelets. Hab.—Valparaiso. This is one of the largest species of the genus. It is when alive of a dirty grey colour ; more flesh-coloured in front. There is a median genital papilla upon xvi. (9) Microscolex robustus (NEW SPECIES). Definition. Length, 72 mm.; diameter, 7 mm.; number of segments, 82. Setae distant, the ventral setae converging on segments XIII-XX. Clitellum, XIV-XVII. Dorsal pores absent. Prostomium complete. Gizzard in VII. Sperm-sacs in IX, XI, Testes in X. Pemial setae long and unornamented. Spermathecae small in IX, with tubular diverticulum. Hab—Teja Island, Valdivia. There are a number of genital papillae, paired on ix, xv, xvi; three on xvii, xviii. (10) Microscolex michaelseni (NEW SPECIES). Definition. Length, 85 mm.; diameter, 3 mm.; number of segments, 92. Setae more closely paired ventrally than laterally. Clitellum, XIII-XVII. Prostomium incomplete. Gizzard rudimentary. Sperm-sacs in XI. Testes in X. Sperm-duct opens behind spermiducal gland on to a groove. Penial setae with spinelets. Spermathecae in VIII, each with two short diverticula. Hab.—Magellan’s Straits, Uschuia, Navarin Island, 8. America. This species is aquatic as well as terrestrial. It is quite bleached by alcohol, and has therefore presumably no integumental pigment when alive. The sperm-ducts and glands open on to a crescentic groove, which extends on to segment xviii. It sometimes happens therefore that the male pores are on xviii. DESCRIPTIONS OF GENERA AND SPECIES 465 (11) Microscolex papillosus (NEW SPECIES). Definition. Length, 87 mm.; diameter, 3 mm.; number of segments, 95. Setae paired. Prostomium incomplete. Clitellum, XIII-XVI. Dorsal pores absent. Genital papillae upon VII-XVII, median unpaired. Gizzard in V. Sperm-sacs in IX, XI. Testes im X. Spermathecae in IX, with spiral diverticulum. Sperm-duct opens just free from spermiducal gland. Penial setae of enormous length (10 mm.), wnornamented. Hab.— Uschuia, 8, America. This species is another of those which have a purple colour. Just in front of the male pores is a deep depression of the integument, This is attached by muscular fibres to the dorsal parietes, and is lined by a tall columnar epithelium. It probably serves as a sucker. The male pores and those of the spermiducal glands open upon very prominent papillae. The diverticulum of the spermathecae ends in a swollen extremity which alone is glandular in structure, being lined by a much-folded epithelium. o (12) Microscolex gracilis (NEW sPECIEs). Definition. Length, 72 mm.; diameter, % mm.; number of segments, 88. Setae distant. Prostomium incomplete. Clitellum, XIII-XVI. No dorsal pores. Gizzard in VI. Sperm- sacs im XI, Testes in X. Spermathecae in IX, with a single stalked diverticulum. Sperm-duct opens into duct of spermiducal gland at some distance from pore. Penial setae not ornamented. Hab.—Uschuia, 8. America. This species has the same colouration as M. diversicolor, and might be confounded with it at first sight. But the incomplete prostomium of the present species serves to differentiate them even without having recourse to the internal structure. It has unusually large ovaries, which however occupy the normal position. The sperm-duct opens on to a papilla, which projects into the interior of the muscular duct of the spermiducal gland. (13) Microscolex corralensis (NEW SPECIES). Definition. Length, 40 mm.; diameter, 4 mm.; number of segments, 70. Setae paired. Prostomium complete. Dorsal pores present. Clitellum, XIII-XVII. Male pores widely separated. Gizzard in VI, VII. Sperm-sacs in XI. Testes in X (2). Spermathecae in IX, with oval diverticulum. Penial setae markedly ornamented with transverse ridges. Hab, — Corral, Valdivia, 8, America. 30 466 OLIGOCHAETA \ (14) Microscolex diversicolor (NEW SPECIES). Definition. Length, 52 mm.; diameter, 3-5 mm.; number of segments, 60. Setae distant. Prostomium complete. Dorsal pores present. Clitellum, XIMI-XVI. Gizzard im FI, Testes in X. Sperm-sacs in IX, XI. Spermiducal gland opens separately from sperm- duct, but near. Penial setae unornamented. Spermathecae in IX, with one large diverticulum. Hab.—Corral, Valdivia. This species varies a good deal in size. I found a few specimens which, though sexually mature, were only 30 mm. in length, and consisted of 100 segments. (15) Microscolex longiseta (NEW SPECIES). Definition. Length, 40 mm.; diameter, 3 mm.; number of segments, 95. Setae strictly pared. Prostomium incomplete. Dorsal pores present. Clitellum, XITI-XVI, incom- plete. Gizzeard in VI, Sperm-sacs in XI. Spermathecae in IX, with long spirally coiled diverticulum. Penial setae 6 mm. long. Hab.—Uschuia, Puerto Pantalon, Puerto Toro (Navarin); in 8. America. This species comes very near to M. papillosus. It has the same inordinately long penial setae and the same curious spiral diverticulum to the spermatheca. It is, however, so much smaller and so devoid of pigment that, as I have examined a large number of individuals, I feel obliged to separate the species. There are some- times, however, traces of a faint purple colour dorsally. (16) Microscolex elegans (EIsEn). Deltania elegans, HISEN, Zoe, iv, 1893, p. 251. Definition. Length, 100 mm. Prostomium incomplete. Clitellum, XIII-XVII. Setae in eight rows, ventral converging on genital segments. No dorsal pores. Nephridia commence in II. No gizzard. Spermathecae single or a pair, without diverticula, Testes in X, XI. Sperm-ducts open into spermiducal gland within body-wall. Penial setae not ornamented, Hab.—San Francisco and neighbourhood. This and the two following species were assigned by EIsEN to a new genus, Deltania, which was stated to differ from Microscolex ‘principally by the deltoid arrangement of the setae in the vicinity of the male pore.’ I am not inclined to allow a separate genus for it. It will be seen that, apart from this very slight difference, the species which are enrolled by Ersen in that genus show no really DESCRIPTIONS OF GENERA AND SPECIES 467 important points of unlikeness from Microscolex. The present species is without egg-sacs and gizzard. The most remarkable characteristic is said by Eisen to be the spermatheca, which is sometimes a median unpaired structure and sometimes paired ; it has, too, excessively thin walls. There are septal glands in segments vi-ix; in vi-vili or v—viii in the two following species. These structures do not seem to occur in other species of the genus. This and the two following species are more fully described by E1sEn in (16). (17) Microscolex troyeri (E1sen). Deltania Troyeri, Etsen, loc. cit., p. 251. Definition. Length, 30mm. Prostomium incomplete ; no dorsal pores. Clitellum, XITI-XVII. Setae in eight rows, ventral converging on genital segment. No gizzard. Spermathecae with paired diverticula. Sperm-ducts open into spermiducal glands within body-wall, Penial setae not ornamented. Hab.—Golden Gate Park, San Francisco. ‘ (18) Microscolex benhami (EIsey). Deltania Benhami, E1sEn, loc. cit., p. 252. Definition. Length, 25 mm. Prostomium incomplete; no dorsal pores. Testes in X, XI. Clitellum, XIII-XVII. Setae in eight rows, ventral converging on genital segments. No gizzard. Spermathecae in IX, with two small diverticula. Spermiducal glands open into spermiducal gland within body-wall. Penial setae not ornamented. Hab.—Alameda county, California. (19) Microscolex monticola (NEW SPECIES). Definition. Length, 31 mm.; diameter, 3 mm.; number of segments, 79. Setae paired, dorsal wider apart than ventral. Prostomium complete, Dorsal pores present. Gizzard m VIII (2%). Testes in X, XI. Sperm-sacs in XII. Spermathecae in IX, with two diverticula. Spermiducal glands long and coiled. Penial setae (2). Hab.—Mount Pirongea, Auckland, New Zealand. In alcohol the single example of this species, which I owe to the kindness of Capt. Brown, was almost black in colour, the setae being implanted upon a white ground. There was no clitellum. 302 468 OLIGOCHAETA Genus PONTODRILUS, PERRIER. Syn. Lumbricus, GRUBE (in part.). Pontoscolex, SCHMARDA (in part.). Cryptodrilus, Rosa (in part.). Photodrilus, GIARD. DEFINITION. Slender worms with eight setae per segment, in pairs, the setae of the dorsal pair being usually further apart than those of the ventral. No dorsal pores. Clitellum complete, XIII-XVII. Male pores XVIII. Spermiducal gland tubular, vasa deferentia opening at junction of glandular and muscular parts. No penial setae. Spermathecae in VIII, IX, with single diverticulum. Gizzard absent or rudimentary; no calciferous glands. Nephridia commence in segment XIII or XV. No subnervian blood-vessel. The principal parts in the structure of this genus have been treated of in con- sidering the characters of the family to which it belongs. Its anatomy was described in great detail by Perrier (9) ten years ago; since that time I have pointed out that certain structures considered by PERRIER to be of doubtful import, are the testes, and that the gizzard is not entirely absent, as he thought, though undoubtedly very rudimentary. I have already given reasons for uniting G1arD’s Photodrilus: with Pontodrilus ; one other species should, I think, be extracted from the heterogeneous assemblage of forms described under the name of ‘Cryptodrilus’ and added to Pontodrilus. The genus Pontodrilus, as I define it here, will therefore contain the five following species :— (1) P. littoralis. European coasts. (2) BP. bermudensis. Brazil; Bermudas; Jamaica. (3) P. hesperidum. Jamaica. ; (4) BP. insularis. Aru Islands. P . phosphoreus. North France. (5) The latter species is placed by Rosa in the genus Cryptodrilus, but not in a decided fashion; he remarks that it is only provisionally so placed, pending a revision of the family Cryptodrilidae. The reasons which lead me to place it in the present genus are, in the first place, the fact that the nephridia do not commence until the thirteenth segment—a character which is only met with in the genus Pontodrilus (among the Cryptodrilids); the gizzard, too, is absent, and there are no calciferous glands. These latter characters, as well as a few others, are not distinctive DESCRIPTIONS OF GENERA AND SPECIES 469 of the genus Pontodrilus ; they would not be of themselves sufficient to place the species in the present genus, but they confirm the justice of this placing. (1) Pontodrilus littoralis (Gruss). Lumbricus littoralis, Gruss, Arch. f. Nat., 1855, p. 127. Pontodrilus Marionis, Perrier, OC. R., 1874, p. 1582. Definition. Length, 100 mm.; diameter, 4 mm.; number of segments, 11 5. Papillae on XX, XXI. Spermathecae with a single diverticulum in VII, VIII. Sperm-sacs im XI, XI. Gizzard rudimentary. Hab—Shores of Mediterranean. There can be hardly any doubt that all the forms described under the above two names are representatives of one and the same species, in spite of the great distance which divides the localities where they occur. P. littoralis and ‘ P. marionis’ have been met with at Villa Franca and Marseilles by Grube and Marion; I received, through the kindness of my late friend Dr. George Hoggan, specimens from Nice. A year or two since I briefly mentioned in the ‘Annals and Magazine of Natural History’ the existence of Pontodrilus at the Bermudas; I assumed that this form was different from the Mediterranean Pontodrilus. A more careful examination of those specimens has confirmed the justice of separating them from the European form. As to ‘P. marionis, PERRIER regarded it as distinct from P. littoralis mainly on account of the differences shown in the genital papillae, but at the same time remarks that the matter must be regarded as doubtful, since he (M. PERRIER) had received examples of the supposed species ‘ P. marionis’ from the exact locality which furnished P. littoralis. A curious fact about this earthworm (and the next) is its habitat. It has been hitherto only met with upon the sea-shore, generally among masses of sea-weed ; the only other species of earthworm which inhabits the same locality is Pontoscolex arenicola. The living specimens of Pontodrilus received from Nice were colourless, that is to say there was no integumental pigment; their reddish colouration was manifestly due to the blood-vessels. (2) Pontodrilus bermudensis, Bepparp. P. bermudensis, BEDDARD, Ann. & Mag. Nat. Hist., Jan. 1891, p. 222. P. arenae, MICHAELSEN, Arch. f. Nat., 1892, p. 222. Pontoscolex arenicola, SCHMARDA, Neue wirbell. Thiere, Bd. I, ii, p. 11 (in part.). 470 OLIGOCHAETA Definition. Length, 80 mm.; number of segments, 120. Setae ornamented, present on eighteenth segment at opening of male ducts, One median papilla between XIX/XX. Hab.— Bermudas ; Jamaica ; Brazil (sea-shore). = This species was originally described by myself from specimens obtained on the island of Bermuda! (24). The description, however, was not at all sufficient to recognize the species, and I subsequently arrived at the conclusion that the supposed species was identical with P. littoralis. MuicHaELsEn’s description of his P. arenae led me to look into the matter again, and as a result I found that my species from Bermuda was probably identical with this P. arenae. Some of the specimens of Scumarpa’s Pontoscolex arenicola proved also to belong to this same species, though it is not necessary on that account to retain this name for the species, for as his figure evidently refers to a ‘ Urochaeta, I retain that name for the genus and for a species of what used to be known by Perrier’s name of Urochaeta hystrix, My. name, however, should evidently have the priority. Since writing the extremely imperfect account of P. bermudensis already quoted, I have re-examined the worm, and find myself able to confirm MICHAELSEN in every particular, though I can add a few minutiae to his description. The male pores open into a long groove which occupies the whole of the segment; there is, of course, a groove on each side. This and the fact that there is only a slight genital papilla distinguishes, as regards external characters, the present species from P. littoralis. The ornamentation of the setae does not occur, so far as I have been able to make out, in the European Pontodrilus; the setae are not modified upon the eighteenth segment, and are present. The muscular duct of the spermiducal gland is much more pronounced in the New World than in the Old World Pontodrilus. MicuarLsEn found the nephridia to commence in the thirteenth segment; I found that more usually they began in xv, but in one specimen in xiii. The clitellum occupies segments xiii-xvil. In other anatomical characters this species does not depart from P. littoralis. The specimens from Bermudas and from Jamaica had their entire alimentary tract filled with the débris of coral rock. So abundantly was the intestine filled with calcareous débris that the body was in places distended beyond its normal size. There was nothing in the gut except this sand; no traces of vegetable matter for example. One is disposed therefore to think that the worms must nourish themselves largely upon the minute animals (Foraminifera, &c.), living among the coral detritus. The absence of a gizzard 1 The increase of synonyms is largely my own fault; Dr. Mrcuartsren wrote to me to inquire if my P. bermudensis agreed with certain characters of a new species which he had in his possession and afterwards described as P. arenae; I could not see any ornamentation in the setae, expecting something more pronounced than what actually is found. I have since satisfied myself beyond a doubt that these setae are ornamented. DESCRIPTIONS OF GENERA AND SPECIES 471 among the aquatic Oligochaeta has usually been put down to the soft nature of their food; just as graminivorous differ from carnivorous birds by the increased muscularity and internal thickening of the analogous organ. But the ‘ food’ of Pontodrilus would seem to need a gizzard for its trituration more than that of any other earthworm, and yet Pontodrilus, though it has a gizzard, has a very feebly developed one. I had expected that the Bermuda specimens would show a greater development of gizzard than those from the Mediterranean shores which feed upon soft sea-weeds, but this was not the case. (3) Pontodrilus hesperidum, Brpparp. P. hesperidum, Bepparp, P. R. Phys. Soc., 1893, p. 37. Definition. Length, about 25 mm.; diameter, 1-5 mm. Setae paired, but the imdividual seta rather distant; setae 2 of segment XVIII absent. Septa V/XIII are thickened, and particularly the last three. Gizzard entirely absent; intestine begins in XV. Last hearts in XIII. Sperm-sacs in XI, XII, Hab,—Jamaica, This is the smallest species of the genus, but as the single individual examined by myself was immature, the account I have given of it was not complete. There is, however, no danger of confounding it with any other species of the genus. The enormous thickness of some of the anterior septa is a noteworthy point about it. I have mentioned in my description of the species that the spermiducal glands are lined by a single layer of cells. This may be simply due to immaturity. (4) Pontodrilus insularis (Rosa). Cryptodrilus insularis, Rosa, Ann. k. Hofm. Wien, vi, 1891, p. 387. Definition. Length, 50 mm.; diameter, 3 mm.; number of segments, 100. Septa VI/XIII very greatly thickened. Rudimentary gizzard in VII. Sperm-sacs im XI, XI. Sperma- thecae in VIII, IX, without diverticula, Hab.—Aru Island. This species was not definitely referred to the genus Cryptodrilus by Rosa, but only ‘provisionally,’ pending a revision of the family ; there can be no doubt, I think, that it is rightly referable to the genus Pontodrilus, as defined in the present work ; the nephridia do not commence until the thirteenth segment, a character which is found in all the species of the genus, though there is some variation in the actual 472 OLIGOCHAETA segment at which they first appear. Rosa examined only two immature examples and his account of the species is therefore not very full. (5) Pontodrilus phosphoreus (Ducts). Lumbricus phosphoreus, Duais, Ann. Sci. Nat. viii (2), 1837, p. 17. Photodrilus phosphoreus, GIARD, C. R., 1887, p. 872. Definition. Length, 50mm.; diameter, 2 mm.; number of segments, 110. Setae in eight rows. Clitellum, XITI-XVII. Hearts in X-XII. Sperm-sacs in XI, XII. Spermathecae in IX with a diverticulum. Hab.—France. This species has been investigated by G1ARD, who however has not yet published an illustrated account of his researches. The main facts in its structure are given in the above definition. In addition to the points there mentioned there exist on segments xii, xiii, and xviii sacs of modified setae in addition to the ordinary ventral setae; instead of a bundle of about four setae there is sometimes only a single seta. This worm appears to be luminous at night, whence the name given to it by Duaks. Genus TYPHAEUS, BEpparp. DEFINITION. Clitellum, XIII-XVII; male pores on XVII. Nephridia diffuse. Testes and funnels a single pair. Spermathecae a single pair. Spermiducal glands tubular, furnished with penial setae. This genus was founded by myself in 1883 for an earthworm from Calcutta; since that time four additional species have been made known by Bourne (8), Rosa (8), and myself (48). Without exception all the species of the genus are natives of India, Ceylon, and Burmah. Although the above definition will serve to distinguish Typhaeus from any other genus of the Cryptodrilidae, there are other characters which are very possibly of generic value, in addition to those already made use of. I have not used these in the definition inasmuch as no definite statements have been made about certain of them in the two species examined by Rosa, which were in a very poor condition for anatomical examination. In all the three species of whose anatomy we possess at all sufficient data the intestine is furnished with a series of about six pairs of reniform glands lying on its dorsal surface. I have described these in T. orientalis and T. gammii ; Bourne has referred to them in 7. masoni ; their minute DESCRIPTIONS OF GENERA AND SPECIES 473 structure has been briefly described and figured by me (48) in 7. gammiu. The glands are made up of a much-folded membrane; their interior is thus divided up into numerous compartments by the folds which seem to anastomose; the structure of the glands is in fact extremely like that of the calciferous glands. Another character of Typhaeus possibly of generic value, i.e. not confined to the species in which alone it has been recorded, is the fact that there is only a single pair of calciferous glands. It is unusual among the Cryptodrilidae for the testes to be limited to one pair: there is no other genus in which this is, as it is in the present, a character which runs through all the species. Corresponding to the single pair of testes and funnels we have only a single pair of sperm-sacs ; these are long and tongue-shaped and extend through several segments as in many Geoscolicidae. The spermiducal glands are long and tubular; the actual mode of their opening on to the exterior has only been studied in 7. gammz. In that species, and very possibly in the others, the sperm-duct perforates the body-wall independently and only joins the gland just before the opening of the latter on to the exterior; the cells of the sperm-duct are ciliated up to the point where they perforate the body-wall, after this they lose the cilia. Opening in common with the spermiducal gland on each side of the body is a sac containing a bundle of penial setae. (zs) Typhaeus orientalis, Bepparp. T. orientalis, BEDDARD, Ann. Mag. Nat. Hist., Oct. 1893, p. 219. Definition. Length, 250 mm. Setae strictly paired. Genital papillae between segments XIIM/XVII, XVII/XX, on a line with ventral setae. Intestinal glands five pairs. Hab.— Neighbourhood of Calcutta. I have described the outer pair of setae as being absent from the clitellar segments of this species; as, however, I have had no opportunity of verifying this upon fresh material I do not utilise the character, if it be really constant, as part of the definition of the species. The gizzard appeared to occupy two segments, the septum dividing which has aborted as in the genus Perichaeta (s.s.); there are only two specially thickened septa, which lie between segments v/vii. The last heart is in segment xiv (?)'. (2) Typhaeus gammii, Bepparp. T, gammii, BEDDARD, Q. J. M. 8., vol. xxix, 1889, p. 111. Definition. Length, about 250 mm.; thickness up to half-an-inch. Setae strictly paired. 1 See remarks upon the following species. 3P 474 OLIGOCHAETA A single large genital papilla between XIX/XX and XX/XXI. Intestinal glands of consecutive segments fused. Hab.— Darjeeling. This species can be distinguished from the last by its greater bulk. It is true that the measurements given appear to indicate a similar size; but the specimens of T. orientalis which I examined were much softened and extended, whereas those of T. gammii were retracted. J. gammii also seems to differ from the last species in having no setae upon the second segment of the body. At the time that this fact was mentioned by me there was no earthworm known in which the setae were absent from any but the first segment ; I therefore mentioned it with greater hesitation than it would be necessary to do now when so many species are known in which this amount of ‘cephalization’ is met with. The dorsal pores commence between the tenth and eleventh segments. The first distinct septum lies between segments iv/v; three thickened septa border segments vii, ix, x posteriorly. The gizzard is in segments vi, vii; the septum which should divide these segments is absent, or at most is represented by two muscular bands which tie down the gizzard to the parietes. These muscles also occur in the last species. Accepting Bourne’s corrections of my enumeration of the segments, I should now refer the single pair of calciferous glands to the thirteenth instead of to the twelfth segment. This segment also contains the last pair of hearts. I expect that a renewed examination of the last species would show that there also the last pair of hearts occupy the same segment. The single pair of testes in the eleventh segment are enclosed within a median unpaired sperm reservoir. The two sperm-sacs are long, reaching back to the seventeenth segment; the sperm-sacs are racethose in form. The spermathecae have, as in the last species, two diverticula; but each of these is multifid instead of being trifid. The shape of the penial setae distinguish this species from 7. orientalis; their free extremity is covered by numerous finely denticulate ridges, whereas in the last species the extremity of the seta has fine obliquely running ridges which give it a bipinnate appearance. (3) Typhaeus masoni, Bourne. T. Masoni, Bourne, J. Asiat. Soc. Bengal, vol. lviii, p. ii. p. 112. Definition. Length, 130 mm. Setae paired anteriorly ; in posterior segments they come to be separated, Genital papillae paired between segments XV/XVI, XV1/XVI, XVII/XIX, XIX/XX. Four pairs of bilobed intestinal glands. Hab.—Dehra Dun. DESCRIPTIONS OF GENERA AND SPECIES 475 This species has been described by Bourne; it chiefly differs from the two species that have been just described in the fact that the setae, as in Geoscolex, become separated by greater intervals posteriorly, being strictly paired anteriorly. The anterior segments are annulate, as in T. gammii, and it is quite possible that there are no differences between the two species in the number of the genital papillae; these structures vary so much in number in individuals that it is most unsafe to draw any distinctions based upon apparent differences that they show. The calciferous glands of this species, though agreeing with those of 7. gammii in being limited to a single pair, are situated in a different segment, i.e. the eleventh or the twelfth. Bourne has stated that the sperm-duct opens into the muscular duct of the spermiducal gland just before the latter penetrates the body-wall; the penial setae are remarkable for the fact that each sac contains setae of two kinds—a somewhat unusual occurrence among the Oligochaeta, though seen in Acanthodrilus georgianus ; some of the setae are smooth at the free extremity, others have the chevron-shaped markings that occur in the penial setae of T. orientalis; the caecal appendages of the spermathecae are bifid or trifid. (4) Typhaeus laevis, Rosa. T. laevis, Rosa, Ann. Mus. Civ. Genova, vol. ix (2 a), 1889, p. 388. Definition. Length, 35 mm.; number of segments, 180. Genital papillae, two pairs on XVII and XVI. Hab.—Burmah ; Ceylon. This species is only very imperfectly known; nothing with regard to the internal characters is contained in Rosa’s (8, 11) account of the species. It is to be distinguished from the three foregoing by its smaller size and by the characters of the papillae. In addition to these distinguishing marks the present species seems to differ by the arrangement of the setae; the two setae of the dorsal pair are separated by wider intervals than are the setae of the ventral pair. Dorsal pores were seen from the intersegmental groove xii/xili. (5) Typhaeus foveatus, Rosa. T. foveatus, Rosa, loc. cit., p. 389. Definition. Length, 180 mm.; number of segments, 170. No genital papillae, Penial setae with minute points irregularly arranged upon the free end. Hab.—Rangoon. This species is not well known; it is not easy to distinguish it from the last; the specimens examined by Rosa were immature; the absence, therefore, of genital BP 2 476 OLIGOCHAETA papillae may very possibly not be a character of specific value; the setae appear to be arranged much as in the last species, as will be seen by a comparison of what Rosa has said with regard to the two worms. T. laevis. Le setole dorsali 3-4 sono sempre pit distanti I-2, lo spazio fra le ventrali e le dorsali nella fra loro che le ventrali parte anteriore del corpo e un po’ mag- giore di quello fra le due setole d’ ogni paio per cui queste sono geminate ma non strettamente posteriormente pero le paia ventrali e dorsali si favvicinano, per cui T. foveatus. Le due setole nelle paia esterne (3-4) sono distanto fra di loro circa il doppio che nelle interne (1-2): lo spazio fra le due paia di un lato (2-3) e maggiore di quello fra le setole esterne (3-4), minore pero dello spazio mediano ventrale (1-1). Tale disposizione & costante per tutta la lunghezza del corpo. lo spazio (2-3) che sta fra le seta o le ventrali e le dorsali e maggiore di quella fra le ventrali (1-2) e minore di quello fra le dorsali (3-4). The dorsal pores commence between segments xi/xii. Concerning the external characters, only enough details are given to show that the present species agrees with the remaining species of the genus. Thickened septa exist between segments iv/vi, viii/xi; the penial setae appear to differ from those of the other species in which they are known by being ornamented at the extremity with a number of minute points arranged indefinitely; some of the setae are, however, smooth’; they are none of them swollen, but are curved; the diverticula of the spermathecae (two, as in other species) are simple without divisions; but then the specimen was immature, and the spermathecae are described as being slightly developed. Genus DICHOGASTER, Brpparp. DEFINITION.—Setae paired. Dorsal pores present. Male pores on XVII. Nephridia diffuse. Clitellum XIII-XX (XXIII). three pairs of calciferous glands. Spermiducal glands tubular. Two gizzards; This genus was created by myself for the reception of an earthworm from the island of Fiji, differing from any other Cryptodrilid in the fact that, behind the 1 Cf. T. masoni, above. DESCRIPTIONS OF GENERA AND SPECIES 477 spermiducal glands of the seventeenth segment, there are two pairs of tubular glands—a pair to each segment—of the same character, though rather smaller. MICHAELSEN (10) has, however, referred two earthworms from tropical Africa to the same genus, which do not show this peculiarity, though agreeing in most other matters with my Dichogaster damonis; by neglecting this character, and also the absence of the ventral setae upon segments xvii, xviii, xix, which both distinguish D. damonis, the genus Dichogaster is reduced to a condition in which it is very difficult to define it. The above definition, however, does exclude the genera Cryptodrilus, Megascolides, and Digaster, in a few comparatively trifling points; thus, in all of those genera the male pores are upon the eighteenth instead of the seventeenth segment. These differences cannot be looked upon as important; but then, hardly any of the points in which many of the genera of Cryptodrilidae differ are important; and it is necessary to divide so large a family into genera; I am not sure that it would not be advisable to retain the name Dichogaster for my species only, and to apply a new name to MICHAELSEN’s species, which show the differences referred to, and are, moreover, peculiar to the Ethiopian region. It may be noted also that there is nothing in MICHAELSEN’s description, which is opposed to uniting with his two species of ‘Dichogaster’ my genus Microdrilus (q. v.). With these preliminary remarks I leave for the present the genus as MICHAELSEN has wished. (1) Dichogaster damonis, BEppaRp. D. damonis, BEDDARD, Q. J. M.S., vol. xxix, 1889, p. 251. Definition. Length, about 4 inches. Clitellum, XIII-XX. Ventral setae of XVII-XIX missing ; three pairs of tubular glands open on to these segments, of which the anterior is connected with sperm-duct. A pair of peptonephridia open into buecal cavity. Hab,—Fiyi. In this species the calciferous glands are in the fifteenth, sixteenth, and seven- teenth segments. The single pair of spermathecae have a single diverticulum; this has very thick walls, and its cavity is much subdivided. I have illustrated the anatomy of this species in my memoir quoted above. (2) Dichogaster mimus, MIcHAELsEN. . D. mimus, MicHarLsEN, Arch. f. Nat., 1891, p. 202. Definition. Length, 40 mm.; number of segments, 350. Clitellum, XIII-XXIII. No peniat setae. Hab.—Accra, West Africa. 478 OLIGOCHAETA MIcHAELSEN states that in this species the spermathecae open in the intersegmental groove viii/ix, whereas in the last species they open a segment in front of this; there is also a similar difference in the position of the calciferous glands, which in D. minus are situated in segments xiv, xv, xvi. The absence of penial setae distinguishes this species and the preceding one also from the next to be described. (3) Dichogaster hupferi, Micnarzsen. D. Hupferi, MicHartsen, J. B. Hamb. wiss., Anst., Bd. ix, 1891, p. 66. Definition. Length, 180 mm.; number of segments, 250. Dorsal pores commence XVIII/XIX. Penial setae present. Four sacs of copulatory setae by the spermathecae, Hab—W. Africa. This species is obviously different from the last; but MIcHAELSEN has been only able to give a short account of it; he has figured the two kinds of modified setae which are different in form, as in Typhaews masoni, and in a species or two of Acanthodrilus. The presence of copulatory setae near the spermathecae also recalls the Acanthodrilidae. Genus DEODRILUS, BEDDARD. DEFINITION. Prostomium absent. Setae strictly paired, truncated in form at the free extremity and ornamented with minute spinelets, absent on the first five segments of the body. Nephridia diffuse. Spermiducal glands lobate, with a sac of penial setae ° This genus is represented by only one species; it is not, therefore, possible to do more than distinguish in a tentative fashion the generic from the specific characters. The two most marked features of the genus Deodrilus are, perhaps, the absence of a prostomium and the form of the setae. In no other genus of Cryptodrilidae is the prostomium aborted (or rather ‘not yet developed,’ should possibly be said in view of VEJDOVSKY’s recent researches (9) ). I have stated its absence in Typhaeus; but, as Bourne has found a prostomium in the species, 7. masoni, described by himself, and as Rosa also referred to the prostomium in the two species which he investigated, it is probable that Typhaeus is not, as I first stated, without a prostomium. I have already commented upon the resemblance which this genus shows to. the Geoscolicidae in this character, as well as in other points. The setae of Deodrilus are peculiar, as regards the Cryptodrilidae, in not having the regular sigmoid form; the extremity has a truncated appearance as if the end had been broken off; DESCRIPTIONS OF GENERA AND SPECIES 479 moreover, the distal extremity is covered by numerous minute spines, a state of affairs rarely met with among the Cryptodrilidae; the only other instance, in fact, is Pontodrilus arenae. It is possible that this genus is also to be distinguished by the presence of only a single pair of testes; at any rate, I could only discover one pair of funnels ; there are, however, two pairs of sperm-sacs in x and xi; as the sperm-sacs generally correspond in number to the testes, the missing testes of the tenth segment may be ultimately forthcoming. The spermiducal glands open on to the eighteenth segment; the penial setae are remarkable in being of two kinds (a not uncommon occurrence, however); there are setae with an ornamentation like that of the ordinary setae of the body; there are also setae of which the distal extremity has transverse ridges. Deodrilus jacksoni, Bepparp. D. Jacksoni, BEDDARD. Q. J. M. S., vol. xxxi, 1891, p. 475. Definition. Length, 325 mm. Genital papillae forming a dumb-bell-shaped area between segments XI/XIT. Two pairs of spermathecae without diverticula in VIII, IX. Hab.— Ceylon, The anterior segments of the body are annulated; the clitellum was not fully developed in the specimen which I examined ; it appeared to extend from the fifteenth to the eighteenth segment. The genital orifices (upon the eighteenth segment) were borne upon two ridges coinciding in position with the ventral setae. The septa lying between segments vi/xiii are specially thickened. There is a gizzard in vi; the ealciferous glands, which are bilobed, lie in segments xv, xvi, xvii; the intestine begins at about the twentieth segment. There appeared to be a ‘mucous gland’ lying beside the pharynx. I have illustrated the anatomy of this species in my paper quoted above. * Genus MILLSONIA, BEpDARD, DEFINITION. Large worms, with strictly paired, ventrally placed setae. Male pores (paired or unpaired) on XVII. Nephridia diffuse. Two gizzards in V, VI. Calciferous glands in XV-XVII. Intestine with about thirty pairs of caeca. Spermathecae without diverticula. Spermiducal glands tubular. No penial setae. 480 OLIGOCHAETA This genus is to be distinguished by two very salient characters: (1) the large number of intestinal caeca, which entirely resemble the single pair of Perichaeta ; and (2) the nephridia; the latter are anteriorly of the ordinary diffuse kind; posteriorly, apparently entirely through the inordinate growth of the vesicular peritoneal cells, each segment appears to be filled with a row of small oval sacs; these are merely the disguised nephridia. (1) Millsonia rubens, Bepparp. M. rubens, Bepparp, P. Z. S., 1894, p. 382. Definition. Length, 320 mm.; diameter, 12 mm.; number of segments, 363. Male pores paired. Clitellum, XIII-XXII. Spermathecae in VIII. Sperm-sacs in XI, XII. No bursa copulatria. Hab.—Tropical W. Africa. The brick-red colour of the worm (in alcohol) suggested its name. The septa begin iv/v, but ix/x is the first which is thickened. The first five segments appear to be without setae (cf. Deodrilus). (2) Millsonia nigra, BeppaRD. M. nigra, BEDDARD, loc. cit., p. 385. Definition. Length, 230 mm.; diameter, 7 mm. Male pores single. Spermathecae in TI, opening VITI/IX. Spermiducal glands open each into a bursa copulatric. Hab.— Tropical W. Africa. The colour of the preserved worm is a very dark brown. As in the last species, there are dorsal pores. The distal end of the 8perm-ducts has a muscular sheath, and opens separately from the spermiducal gland into the bursa. The latter is a thick- walled sac, something like that of Geoscolex, and seven mm. long. The spermathecae perforate septum vii/viii, and come to lie in the former segment, though the external pore is between viii/ix. The very first septum (iv/v), and thence to xiii/xiv, are thickened. Genus FLETCHERODRILUS, MIcHAELSEN. Syn. Cryptodrilus, FLETCHER (in part.). DEFINITION. Setae in eight rows. Male pore and spermathecal pores in a single median unpaired series. Nephridia paired. Spermiducal glands tubular. Spermathecae one to each segment, with a pair of diverticula. No penial setae. DESCRIPTIONS OF GENERA AND SPECIES 481 I follow Micuarzsrn in allowing only a single species of this genus, which must be named— Fletcherodrilus unicus, Fietcuer. Cryptodrilus(?) unicus, FLetcuEr, Proc. Linn. Soe. N. S. W., iii. (2), 1889, p. 1540. C. purpureus, MICHAELSEN, JB. Hamb. wiss. Anst., vi, 1889, p. 3. Cryptodrilus (?) purpureus, FLEtcHer, Proc. Linn. Soc. N. 8. W., iv. (2), 1890, P- 99°. C. (?) fasciatus, FLETCHER, p. 988. Fletcherodrilus unicus, MicHaELsEeN, JB. Hamb. wiss. Anst., vili, 1891, p. 29. Definition. Length, up to 325 mm.; breadth, 10 mm.; number of segments, 159. Dorsal pores commence between IV/V. Gizzard in VI; three pairs of calciferous glands in XII-XV. Clitellwm, XITI-XVITIT. — Sperm-sacs in segments IX-XII. Last pair of hearts in XIT. Hab.— Queensland ; N.S. Wales ; Pelew Islands. Although MicHaELsen stated that his C. purpureus agreed ‘ point for point’ with FLETCHER’s C. unicus, the latter author retained the two species, adding to them a third species, C. fasciatus. After the publication of the paper in which FLETcHER distinguished the three species, MICHAELSEN again emphasized the real identity of the three ; FLEeTcHER used as points of difference the stouter form of the body in the species ‘fasciatus, and also mentioned that the setae are straight in ‘fasciatus,’ while they are sinuous in ‘purpureus. The irregularity of the setae, however, varies very much in individuals, and is, perhaps, therefore, hardly to be used as a specific character. Some worms from Percy Island, described by FLETCHER as ‘incertae sedis,’ appear, according to his latest opinion, to be referable to this species. The examples from the Pelew Islands are much larger than the others. The additional pair of sperm-sacs described by FLErcHeER, on the posterior face of the septum xii/xili, are possibly egg-sacs (cf. Perichaeta, see p. 97). Genus TRINEPHRUS, BreppDarp. Syn. Cryptodrilus, FLETCHER, SPENCER (in part.). DEFINITION. Three pairs of nephridia in each segment. Spermiducal glands either lobate or tubular. 3 482 OLIGOCHAETA This genus, like many others of the Cryptodrilidae, is by no means altogether satisfactory; but it represents the best that the facts at hand permit of. The presence of three distinct and separate pairs of nephridia in a single segment appears to me to be so remarkable a character that the species thus distinguished from other Cryptodrilidae deserve generic separation. It is, however, only by this character that they can be separated from other species of Cryptodrilus and Meguscolides. If the two species, fastigatus and dubius, were the only two Cryptodrilidae that showed this arrangement of the nephridia, the genus would be much more easily definable ; but 7. tenuis and T. mediocris, particularly the latter, differ from those two in a good many particulars, as may be seen by an inspection of the table on p. 448. It may be convenient to recapitulate here in a tabular form the main characters of the four species which I here relegate to the genus Trinephrus. T. FASTIGATUS. T. TENUIS. T. MEDIOCRIS. T. DUBIUS. Prostomium. . . . complete complete incomplete complete Dorsal pores. . . . from iv/v ? from xi/xii from v/vi Spermathecae . . . two caeca one caecum one caecum two caeca Sperm-sacs . . . . xi, xii 3 ix, xii xi, xii Spermiducal glands . iv, tubular ii, tubular ii, lobate iv, tubular 4 Unfortunately, the form of the spermiducal glands is not quite certain in the four species; SPENCER describes them as a ‘coiled tubular mass,’ but distinctly figures them as of the lobate kind. FLETcHer’s expression, ‘incised glands, applied to these organs in 7’. mediocris, seems to indicate that they are lobate. It will be seen, therefore, that 7. mediocris differs from the three other species in having an incomplete prostomium, lobate spermiducal glands, and sperm-sacs in segments ix, xii; and that the three remaining species, as regards these characters, differ from TI. mediocris, but agree with each other. The agreement between TJ. fastigatus and 7. dubius is closest. It would be a relief to find that the nephridia of the species, which I call for the present 7. mediocris, were not paired but diffuse. It will be noticed from the tables on p. 448 that the Cryptodrilidae, referred to the genera Megascolides and Cryptodrilus by FLETCHER and SPENCER, can be arranged in. three parallel series under the two divisions of those with lobate, and those with tubular, spermiducal glands; in each group are worms with diffuse, paired and three-paired nephridia. DESCRIPTIONS OF GENERA AND SPECIES 483 (1) Trinephrus fastigatus (FurtcHen). Cryptodrilus fastigatus, FLeTcHER, Proc. Linn. Soc. N.S. W. (2), ili, 1889, p. 1541. Definition. Length, 89 mm.; diameter, 4 mm.; number of segments, 140. Prostomium completely dividing buccal ring. Clitellum, XIV-XVII complete. Setae of outer couples further apart than of inner couples, Male pores opposite first seta; ventral surface of segment XVIIT tumid. Oviduet pores in front and ventrad of seta I. Dorsal pores commence between IV/V. Gizzard in V; large intestine begins in XVIIE. Sperm-sacs in XI, XII. Spermathecae in VIII, 1X, with two caeca. Spermiducal glands four, two of each side unite before opening, Last hearts in XII. Hab.— Burrawang and Illawarra, N.S. Wales. FLETCHER describes what appear to be egg-sacs in segments xiii and xiv. The spermiducal glands occupy respectively segments xviii and xix-xxi; the ducts of the two of each side unite to form a single duct which is bent upon itself; the sperm-duct joins the ducts of these glands just after their union. In one specimen the last pair of hearts was in segment xiii. (2) Trinephrus tenuis (FLETCHER). Cryptodrilus tenuis, FLETCHER, loc. cit., p. 1543. Definition. Length, go mm.; diameter, 4 mm.; number of segments, 190. Prostomium complete. Setae of outer couples further away than of inner. Male pores between setae of inner couples. Spermathecae with a single rather rudimentary caecum. Spermiducal glands single on each side and tubular. Hab—Braidwood, N. 8. W. This species is, owing to the immaturity of the examples, incompletely described by FLETCHER ; in addition to the points noticed in the above, he says that the dorsal pores commence further forward than in the last species; it also has a much paler colour. (3) Trinephrus mediocris (FLETCHER). Cryptodrilus mediocris, FLETCHER, loc. cit., p. 1544. Definition. Length, 65 mm.; diameter, 3°5 mm.; number of segments, 125. Prostomium does not divide buceal ring. Setae of outer couple further apart than of inner. Clitellum, XTII-XVII, complete. Male pores just dorsad of setae I; between X/XI a pair of papillae ; similar pairs between XV/XVI, XVI/XVII, XIX/XX, XX/XXI; also a pair on XVII or XVIII. Dorsal pores commence XI/XII. Gizzard in V, intestine begins in 392 484 OLIGOCHAETA XIT. Last pair of hearts in XII. Sperm-sacs in IX, XII; spermathecae in VIL, IX, with a single diverticulum. Hab—Near Paramatta, Sydney. (4) Trinephrus dubius (SPENcER). Cryptodrilus dubius, Spencer, P. R. Soc. Vict., 1891, p. 136. Definition. Length, ‘three and a half inches’; diameter, ‘less than a quarter inch, Prostomium complete. Setae of outer couple further apart than of tmner, Male pores ventral of level of setae 2. Paired papillae on X VIL, median papilla on X VINT/XVIIL Dorsal pores commence V/VI. Gizzard in V; calciferous glands in XV, XVI; intestine begins in XVIIT, Sperm-sacs in XI, XII; spermathecae in VIII, LX, with two diverticula, Spermiducal glands two pairs as in T. fastigatus. Hab.—Vietoria. SPENCER remarks that this species is to be distinguished from T. fastigatus by the possession of well-developed calciferous glands and by the sperm-sac not being racemose; the two are evidently very closely allied. Genus DIGASTER, PERRIER. Syn. Perissogaster, FLETCHER. Didymogaster, FLETCHER. DEFINITION. Prostomium incompletely divides buccal ring. Clitellum, XIII (XIV)-XVII (XVIII). Gizzards, two or three. Nephridia diffuse. Spermi- ducal glands lobate. . T have already given my reasons for associating the three genera Digaster, Perisso- gaster, and Didymogaster into one genus, which must obviously be called Digaster. As thus constituted the genus will contain seven species. It is, as I have already indicated, very close to Cryptodrilus. The most remarkable species in the genus is perhaps D. sylvaticus, with its spirally- arranged intestine; this character is, however, found elsewhere among the terricilous Oligochaeta, for it has been described by BenHAM in Plagiochaeta. There are two other genera of Cryptodrilids nearly allied to the present which possess two gizzards ; these are Dichogaster and Microdrilus; but the present genus differs from both of these in having the male pores upon the eighteenth segment instead of the seventeenth. The two genera mentioned have also tubular spermiducal glands. On these grounds chiefly, though there are also minor points of difference, I distinguish both of them from each other and from Digaster. The type species of Digaster is D. lumbricoides. DESCRIPTIONS OF GENERA AND SPECIES 485 (1) Digaster lumbricoides (Perrier). D. lumbricoides, PERRimR, Nouv. Arch. Mus., 1872, p. 94. Definition. Clitellum, XIV-XVI. Male pores on XVII(?); a pair of papillae on segments im front of and’ behind that carrying male pores. Dorsal pores commence I V/V. Gizeards two in V, VIL. Sperm-sacs in X, XI. Hab.—Port Macquarie, Australia. PERRIER’S description is not very exhaustive; and it is indeed not at all certain whether the species really belongs to the genus Digaster as here defined, in which case, of course, the name will have to be altered. He states, for instance, that the male pores are upon the seventeenth segment. Nothing is said with regard to the nephridia. (2) Digaster queenslandica (FLETCHER). Perissogaster Queenslandica, FLETCHER, Proc. Linn. Soc., N.S. W. (2), iii, 1889, Pp. 1529. Definition. Length, 158 mm.; diameter, 8 mm.; number of segments, 2.20. Prostomium incomplete. Setae of outer couples further apart than of inner, slightly sinuous. Male pores corresponding to interval between setae one and two, Dorsal pores commence III/IV. Gizzards three in V-VII; calciferous glands in XIV, XV. Last pair of hearts in XII. Sperm-sacs in XI, XI. Spermathecae in VIII, 1X, with a rosette-like caecum. No penial setae. Hab.—Ouley, near Brisbane. FLETCHER speaks of the sperm-sacs as occupying segments xi—xili; I think, how- ever, that in all probability the last pair of reputed sperm-sacs are egg-sacs. (3) Digaster perrieri, FLetcuer. D. Perrieri, FLETcHER, loc. cit., p. 1530. Definition. Length, 90 mm.; diameter, 5 mm.; number of segments, 155. Prostomium incomplete. Clitellum, XIV-XVII complete. Setae of outer couples further apart than of inner. Dorsal pores commence X/XI. Papillae on X, XI or IX-XII, and XVII-XIX, Gizzards two. Sperm-sacs in XI, XII. Penial setae with serrated extremity. Hab.— Springwood, N.S. W. This species is compared by FLETCHER with D. armifera ; and both are contrasted with D. lumbricoides. He says nothing about the spermathecae. 486 OLIGOCHAETA (4) Digaster excavata (FLETCHER). Perissogaster excavata, FLETCHER, loe. cit., ii. (2), 1888, p. 383. Definition. Length, 334 mm.; breadth, 15 mm.; number of segments, 195. Prostomium incomplete. Clitellum, XHI-X VIL, complete except for three fossae in front of behind enclosing male pores. Setae in eight rows; those of outer couple further apart than inner. Oviducal pores 2mm. apart. Dorsal pores absent. Giezards, three in V-VII; no distinct calciferous glands; intestine begins in XVI, arranged in a spiral. Septa, VII/XIV, thickened. Last pair of hearts in XII. Sperm-sacs in IX, XII; sperm- reservoirs in X, XI. Spermathecae in VIII, IX, with bifid or trifid diverticulum, opening in Line with seta 1. Hab.—Morpeth, Hawkesbury river, N.S. W. (5) Digaster nemoralis (FLETCHER). Perissogaster nemoralis, FLETCHER, loc. cit., iii (2), 1889, p. 1527. Definition. Length, 130 mm.; breadth, 6mm.; number of segments,245. Prostomium incom- plete. Setae in eight rows, outer couple further apart than inner, Clitellum, XITI-XVIZ1, complete, except where papillae occupy ventral space. Male pores in line with interval between setae one and two. Genital papillae, two pairs, between XVI/XVII, XVILII/XIX. Dorsal pores begin X/XI. Gizzards, three in V—VII; calciferous glands in X—XIV ; intestine begins in XVII; it has a typhtlosole. Last pair of hearts in XII, Sperm-sacs in IX, XI, XII. Spermathecae in VIII, IX, with short diverticulum. Penial setae present. Peptonephridia in IV, Hab.—Gosford, N. 8. W. (6) Digaster armifera, FLercuer. D. armifera, FLETcHER, loc. cit. i (2), 1887, p. 947. Definition. Length, 125 mm.; diameter, 5 mm.; number of segments, 205. Prostomium incomplete. Clitellum, XIV-XVIL. Setae of outer couples further apart than of inner. Papillae a swollen ridge on XVII, XIX and XI, XII. Dorsal pores commence XII/XILI. Gizzards two in V, VI; intestine begins in XVII. Anterior nephridia modified into peptonephridia. Last hearts in XII. Anterior septa up to XII/XIIL thickened. Sperm- sacs in XI, XII. Spermathecae in VIIT, IX, with rudimentary caecum. Penial setae, extremity ornamented with circular serrated ridges. Hab.—Warrickville, near Sydney, Auburn, near Paramatta, N.S. W. With some doubt FLercHer refers some species from Percy Island to the same species. The characters of these were insufficiently defined to permit of certainty in the matter. DESCRIPTIONS OF GENERA AND SPECIES 487 (7) Digaster sylvaticus (FLETCHER). Didymogaster sylvaticus, FLETCHER, loc. cit., P: 554+ Definition. Length, 80 mm.; diameter, 12 mm.; number of segments, 120. Prostomiwm incomplete. Clitellum, XIII-XVIII, Setae of outer row sinuous. Dorsal pores commence V/VI. Oviducal pores close to median line. Gizzards in VI, VII; intestine arranged an a corkscrew fashion. Last hearts in XIII ; supraintestinal trunk double. Sperm-sacs mm IX, XII; spermathecae in VIII, IX, with small pyriform caecum. Hab.— Burrawang, Springwood, Jervis Bay, N. 8. W. FLETCHER mentions in this species in each of the four segments v-ix a pair of peculiar bodies on either side of oesophagus richly supplied with blood-vessels, but is unable to suggest their nature. There is evidently an inaccuracy with regard to the spermathecae somewhere, either in the description or figure; he describes them as lying in segments vii, ix, but seems to figure three pairs in vii, viii, ix. Genus MEGASCOLIDES, McCoy. Syn. Cryptodrilus, FLETCHER, et alii (in part.). Plutellus, BENHAM (? non PERRIER). DEFINITION. WNephridia paired. Spermiducal glands in XVIII, tubular in form. As has already been pointed out there are no differences of importance which serve to distinguish Plutellus from Megascolides. The wide separation in range is the only reason indeed which could possibly, in my opinion, lead to their generic separation; and this, be it observed, is curiously paralleled by the Marsupials. This being the case, the name Megascolides ought to be dropped in favour of Plutellus ; but I do not consider it to be yet proved that Benuam’s P. perriert is congeneric with Prrrrer’s P. heteroporus. The latter species has been stated to possess ovaries which are situated in front of the testes. This is, of course, if true, a unique case ; so too is its other distinguishing feature, viz. the fact that the nephridia are confined to one segment, the funnel not lying, as is elsewhere invariably the arrangement, in front of the septum. No doubt many naturalists have thrown doubts upon PERRIER’s statements concerning these two important points, and it must be admitted that they seem from our present knowledge to be improbable; nevertheless, no great harm will be done if we leave the matter for further proof, and regard the genus Plutellus as ‘ incertae sedis. BenHam’s species will be treated as a Megascolides. The species are here grouped according to the number of spermathecae and sperm- sacs. It is noteworthy that only one of the species which has only a single pair 488 OLIGOCHAETA of sperm-sacs has also only a single pair of testes. In the allied Cryptodrilus one pair of sperm-sacs almost always means one pair of testes. Spermathecae in viii, ix. narrensis . lucasi . incertus Sperm-saes . attenuatus . tuberculatus M. M M M M M. M. M. M. sinuosus M. semicinctus M. australis Sperm-sacs M. ornatus M. papillifer Sperm-sacs M. orthostichon Spermathecae in v—ix. M. victoriae M. tasmanianus Sperm-sacs i M. willsiensis M. tanjilensis Sperm-sacs i M. frenchi M. gippslandicus Sperm-sacs Spermathecae in vii, viii. M. manni Spermathecae in vi-ix. M. macedonensis 9 perm-sacs M. perrieri M. smithi Sperm-sacs Spermathecae ? M. rubens Sperm-sacs (1) Megascolides victoriae (SrENczr). roseus minor intermedius Sperm-sacs i in in in in in in Cryptodrilus victoriae, Spencer, P. R. Soc. Vict., 1892, p. 139. Definition. Length, 1oomm.; breadth, 10mm. Clitellum, XIV-XVI (or XHE-XVII ); Setae irregular, at extreme end of body. Dorsal pores commence III/IV. Male pores slightly dorsal to level of setae one. Genital papillae: a ventral patch on IX-XI; three pairs on XVI/XVII, XVII/XVIII, XVIII/XIX, the middle pair being to outside of the others. Gizzard in V ; no calciferous glands ; intestine begins in XVII. Sperm-sacs in IX, XIT; spermathecae in V-IX, with diverticulum one-third of length of pouch. Hab.—- Warburton, Yarra Falley. ix, xii. Xi. xXi-xiv. X—Xxil. 1X—xil. Xi. 1x, X. Xii. ix, Xli. Xil. DESCRIPTIONS OF GENERA AND SPECIES 489 SPENCER describes two varieties of this species which appear to be rather smaller ; they also differ in the presence of a ‘curious elongate white smooth surface’ extending from segment xvii—xxiii’, and sometimes also on segments iv-ix. The spermathecal pores are slightly dorsal of the third seta, and have either a longer or a much shorter duct. (2) Megascolides narrensis (SPENCER). Cryptodrilus narrensis, SPENCER, loc. cit., p. 142. Definition. Length, 40 mm.; breadth, 3mm. Clitellum XUI-XVIII, complete. Setae, outer further apart than inner ; towards posterior end of’ body rows gradually separate until the fourth becomes dorsal in position. Male pores on level with interval between two setae on inner pair. Oviducal pores in front of and ventral to inner seta. Genital papillae two, one on XVII the other on XVIL/XIX. Gizzard in V; no calciferous glands ; intestine begins in XX. Sperm-sacs in IX, XII. Spermathecae in VII, IX, diverticulum one-third. Hab.—Narre Warren, Gippsland, (3) Megascolides lucasi (SPENCER). Cryptodrilus lucasi, SPENCER, loc. cit., p. 143. Definition. Length, 110mm.; breadth, 3-4 mm. Clitellum XTTI-XVIII, complete except on XVID, XVII. Setae all close to ventral surface; outer rows irregular posteriorly. Male pores between setae one and two. Oviducal pores slightly anterior to and ventral of the inner seta. Dorsal pores commence IV/V. Gizzard in V; no glands ; intestine begins in XV. Sperm-sac in IX, XII; spermathecae in VIII, IX, rosette-shaped diverti- culum. Hab.—Tallarook, Goulburn River. This species is stated by SPENCER occasionally to possess an additional pair of ovaries in xiv; he figures also a second pair of oviducts in xii. (4) Megascolides minor (SPzncER). Cryptodrilus minor, SPENCER, loc. cit., p. 144. Definition. Length, 100 mm.; ‘very narrow. Prostomium incomplete. Clitellum, XIV-XVIII. Male pores on level with interval between setae 1 and 2. Setae become irregular at end of body ; anteriorly strictly paired. Oviducal pores anterior to and ventral of the wner seta. Dorsal pores commence behind clitellum. Genital papillae, two elliptical patches 1 Compare (perhaps) Eudriloides (below). 3R 490 OLIGOCHAETA on XVII, XIX. Gizzard in V; no calciferous glands. Intestine begins in XX. Testes one pair (in XI). Sperm-sac in XII. Spermathecae in VIII, IX. Diverticulum trifid. Hab.—8. Warragul, Gippstand. (5) Megascolides manni, SPENcER. M. manni, SPENCER, loc. cit., p. 149. Definition. Length, 250 mm.; breadth, 6 mm. Prostomium incomplete. Clitellum, AIV-XVIII, complete. Setae of outer couple slightly further apart than those of inner. Male pores slightly ventral of level of inner seta, Oviducal pores ventral of level of imner seta. Genital papillae single on XVII/XVIII, XVILI/XIX. Dorsal pores begin behind clitellum. Gizzard in V, VI; no caleiferous glands. Intestine begins in XVIII, Sperm- sacs in XI, XIT; spermathecae in VII, VIII, smati round diverticulum. Hab.—S. Warragul, Gippsland. Of this worm a variety is described which has circular instead of club-shaped genital papillae. SPENCER mentions tufts of nephridial tubes in v-vii. (6) Megascolides incertus, SPENncrR. M. incertus, SPENCER, loc. cit., p. 151. Definition. Length, 250mm. ; breadth, 6mm, Clitellum, XIII-XVILII, Prostomium complete. Setae of outer couple twice as far away as those of inner. Male pores on level with interval between setae 1 and 2. Oviducal pores anterior to and ventral of inner setae. Genital papillae on XVI/XVIT, XIX/XXIII, the latter series getting smaller from before backwards. Gizzard in VI; no caleiferous glands, not even swellings of oesophagus ; intestine begins in XVIII, Sperm-sacs in [X, XI; spermathecae in VIII, IX; diverti- culum minute. Hab.—Victoria (% exact locality). (7) Megascolides sinuosus, SPENncER. M. sinuosus, SPENCER, loc. cit., p. 152. Definition. Length, 500 mm.; breadth, 7 mm, Prostomium incomplete. Clitellum’? Setae of outer couple far apart ; outer rows sinuous in middle and end of body. Oviducal pores anterior to and ventral of inner setae. Genital papillae single on XIX/XX, XX/XXI, Gizzard in V ; vascular swellings in 13-17; intestine begins in XVIII. Last heart in XIII. Excretory system diffuse. Sperm-sacs in XII; spermathecae VIII, IX, with short diverticulum. Hab— Dandenong Ranges. DESCRIPTIONS OF GENERA AND SPECIES 491 (8) Megascolides roseus, SPENCER. M. roseus, SPENCER, loc. cit., p. 153. Definition. Length, 175 mm.; breadth, 6 mm. Prostomium complete. Clitellum complete, XTII-XVUI ; saddle-shaped in XVI-XVULI. Setae of each couple close together anteriorly behind, further away. Male pores on a level with interval between two setae on inner pair. Oviducal pores ventral of and anterior to innermost seta. Genital papillae: one between male pores, a pair on XVII, four pairs on XIX/XXIII, getting to be closer together behind. Dorsal pores commence behind clitellum. Gizeard in V : calciferous glands in XV, XVI; intestine begins in XVIII. Sperm-sacs in XII; sperma- thecae VIII, IX, rosette-shaped diverticulum. Hab.— Warragul. (9) Megascolides attenuatus, SPENCER. M. attenuatus, SPENCER, loe. cit., p. 155. Definition. Length, 200 mm; breadth, 1-3 mm. Prostomium incomplete. Clitellum, ATTI-XVILI. Setae of outer couple slightly further apart than ventral. Fourth row irregular im last ten segments. Oviducal pores in front of ventral of inner seta. Dorsal pores commence V/VI. Gizzard in V; no calciferous glands. Sperm-sacs in IX, XII; spermathecae VIII, IX, with small diverticulum. Hab.—Warragul. SPENCER mentions that there are numerous minute grape-like processes round spermiducal glands; these may be glands such as occur in this situation in Perichaeta. (tc) Megascolides rubens (FLETCHER). Cryptodrilus rubens, FLETCHER, Proc. Linn. Soc. N. 8. W., ii (2), 1888, p. 381. Definition. Length, 55 mm.; breadth, 4 mm.; number of segments, 114. Prostomium incomplete. Clitellum, SIGE, VI, complete. Setae in eight rows ; ventral closer together. Male pores in line with second seta; in front of and behind each a small papilla, through one of which protrude (2) penial setae. Dorsal pores absent. Calciferous glands in X-XIII; intestine begins in XVI. Last hearts in XII, Sperm-sacs in XII only, but two pairs of funnels. Spermathecae (2). Penial setae present. Hab.—Mount Wilson. FLETCHER remarks that in segments vi and vii is a thin walled globular portion of oesophagus, both of which may be gizzards. 3R2 492 OLIGOCHAETA (11) Megascolides tasmanianus (FLETCHER). Notoscolex tasmanianus, FLETCHER, loc. cit., p. 607. Definition. Length, 570 mm.; breadth, 1mm. ; number of segments, about 200. Prostomium incomplete. Clitellum, XITI-XXII. Setae in eight rows, the outer row further back, the other row generally sinuous. Male pores on interval between setae 1 and 2. Oviducal pores to inside of inner seta. Dorsal pores commence between segments XII/XIII. Gizzard in V ; no separate calciferous glands ; intestine begins about XIX. Last heart in XIII. Septa, V/XIII, thickened. Sperm-sacs in IX, XII; spermathecae without caeca in "IX. Hab.—N. E. Tasmania. (12) Megascolides gippslandicus (SPENCER). Cryptodrilus gippslandicus, SpenceR, P. R. Soc. Vict., 1892, p. 132. Definition. Prostomium complete. Clitellum, XUL-XVIL, only developed dorsally. Setae anteriorly in couples, posteriorly irreguiar, Male pores on level with interval between two inner setae. Ovidueal pores ventral of and anterior to innermost seta. Dorsal pores commence III/IV. Gizzard in V; calciferous glands in XIV, XV; intestine begins in XVII. Dorsal vessel double from segment VI to near end of body. Sperm-sacs in IX, X; spermathecae in V-IX ; diverticulum one-quarter length of sac simple. Hab.— Croajingolong, East Gippsland. (13) Megascolides intermedius (SrEncer). Cryptodrilus intermedius, SPENCER, loc. cit., p. 133. Definition. Length, 175 mm.; breadth, 6 mm. Prostomium incomplete. Clitellum, XIV-XVIIT. Setae in couples encept at very posterior end, where outer irregular. Male pores on level of first seta. Oviducal pores ventral of and anterior to first seta. Dorsal pores commence V/VI. Gizzard in V; no separate calciferous glands ; intestine begins in XIX. Last heart in XIII. Testes one pair. Sperm-sacs attached to anterior wall of XII. Spermathecae in VIII, IX; small rosette-like diverticulum. Hab.— 8S. Warragul, Gipgstand. This species is stated by SpENcER to have a second pair of sperm-sacs in xiv; these must surely be the egg-sacs. DESCRIPTIONS OF GENERA AND SPECIES 493 (14) Megascolides tanjilensis (SrEncrr). Cryptodrilus tanjilensis, SPENCER, loc. cit., p. 134. Definition. Length, 137 mm.; breadth, 12 mm. Prostomium complete. Clitellum complete, XIII-XVII. Setae with outer couple wider apart than inner. Male pores in line with interval between setae 1 and 2. Oviducal pores ventral of and anterior to seta 1. Genital papillae on XVI, XVILI/XIX on level with innermost seta; on XVII/XVIII considerably to outside of this. Gizzard in V ; no calciferous glands ; intestine begins im XVIII. Sperm-sacs in XII. Spermathecae in V-IX; diverticulum, one-quarter of length of pouch, simple. Hab.—Tanjil track, near sowree of Yarra. (15) Megascolides frenchi (SrEnczr). Cryptodrilus frenchi, SPENCER, loc. cit., Pp. 135. Definition. Length, 75 mm. ; breadth, 3mm. Prostomium incomplete. Clitellum, XIV-XVI, ‘not very distinctly marked ventrally” Setae irregular posteriorly ; inner closer than outer. Male pores on level with interval between setae 1 and 2. Oviducal pores ventral to inner setae. Genital papillae: on X, XI, XVI/XXI, on level with interval between setae 1/2. Dorsal pores commence IV/V. Gizzeard in VI; no calciferous glands, Sperm-sacs on anterior wall of X, posterior wall of IX. Spermathecae in V-IX; diverticulum one-third length of sac. Hab—Croajingolong, East Gippsland. (16) Megascolides macedonensis (SPENCER). Cryptodrilus macedonensis, SPENCER, loc. cit., p. 138. Definition. Length, 75 mm.; breadth, 3mm. Prostomium incomplete. Clitellum, XIV-XVII, complete. Setae with greater distance between two setae of dorsal couple. Male pores in line with interval between setae 1 and 2 Oviducal pores anterior to and ventral of inner seta. Genital papillae large, covering ventral surface of the segments, on IX/X, X/XI, XVIU/XXI. Dorsal pores commence IV/V. Gizzard in V ; no caleiferous glands ; intestine begins in XVII. Sperm-sacs in XII; spermathecae in VI-IX, with small diverticulum. Hab —Mount Macedon, Victoria. (17) Megascolides willsiensis (SPENCER). Cryptodrilus willsiensis, SPENCER, loc. cit., p. 140. Definition. Length, 187 mm.; breadth, 12 mm. Clitellum, XIV-XVII. Setae of outer 494 OLIGOCHAETA pair much further apart than ventral, irregular posteriorly. Male pores on level with interval between two rows of ventral setae. Gizzard in V ; no calciferous glands ; intestine begins in XVIII. Dorsal vessel double from segment V. Sperm-sacs in IX (posterior wall) and XII (anterior wall). Spermathecae in V-IX, each with two diverticula. Hab—Mount Wills. This species has occasionally as many as five setae on each side of posterior segments. (18) Megascolides smithi (FLETCHER). Cryptodrilus Smithi, FiutcHer, Proc. Linn. Soc., N.S. W., iv (2), 1890, p. 992. Definition. Length, 145 mm.; breadth, 3 mm.; number of segments, 170. Prostomium incomplete. Clitellum, XIV—XVII, complete. Setae, four couples, separated by an unusually wide interval; setae of dorsal pair further away than those of ventral. Oviducal pores in front and a little ventrad of first seta. Genital papillae, a ‘pair on groove between each of segments XV/XX. Dorsal pores commence IV/V. Gizzard in V (or VI); no distinct caleiferous glands; intestine in XVIII. Sperm-sacs in IX, XII. Last pair of hearts in XII, Spermathecae in VI-IX, with small diverticulum opening in line with oviducal pores. Hab.—EKltham, Victoria. * (19) Megascolides tuberculatus (FLETCHER). Notoscolex tuberculatus, FLeTcHER, loc. cit., ii (2), 1888, p. 611. Definition. Length, 350 mm.; breadth, 7mm.; number of segments, 280. Prostomium incomplete. Clitellum, XIII-XVIII. Setae ip eight rows, the outer a little further apart than the inner. Male pores in line with interval between ventral setae. Oviducal pores in front of and ventrad of first seta. Genital papillae represented by a ‘dumb-bell-shaped fossa’ on segments XVII-XXII. Dorsal pores commence XIJ/XIII. Gizzard in V; separate calciferous glands absent ; intestine begins in XVIII ; salivary glands (? nephridial) in V, VIL Septa VII/XIIL thickened. Last hearts in XII. Sperm-sacs im IX, XII. Spermathecae in VIII, IX, each with a minute caecum, Penial setae present. Hab.— Gippsland, Victoria. FLETCHER remarks of this species that it is extremely slender. (20) Megascolides semicinctus (FLETCHER). Cryptodrilus semicinctus, FLETCHER, loc. cit., iv (2), 1890, p. 996. Definition. Length, 54 mm.; breadth, 3mm.; number of segments, about 100. Prostomium DESCRIPTIONS OF GENERA AND SPECIES 495 incomplete. Clitellum, XITI-XVIL, saddle-shaped. Setae of outer couples further apart than inner. Male pores in line with seta 2. Oviducal pores in Sront of, and ventrad of, inner seta. Genital papillue, one in front and one behind, and rather dorsal of, each male pore ; intersegmental in position. Dorsal pores commence X VITI/XIX. Gizzard in V; no distinct caleiferous glands ; intestine begins in XVI. Testes and Junnels, one pair only ; sperm-sacs in XII. Spermathecae in VIII, IX, each with two (or three) caeca, Last hearts im XII, Pemial setae present. Hab.—Grafton, Clarence River, N. 8. Wales. (21) Megascolides ornatus (E1ssn). Argilophilus marmoratus ornatus, EISEN, Zoe, iv, p. 253. Definition. Length, about 150 mm. Clitellum, XIII-XVIII, Genital papillae paired on VILI/X, XV/XVIL, X1X/XX, intersegmental ; ventral setae closer together than lateral. No catciferous glands. Last hearts in XIV. Spermathecae in VIII, IX. Sperm-sacs in X-XIT, Nephridia without terminal vesicle, alternate in position. Penial setae ornamented with spines. Hab.—San Francisco to Oregon. This and the following species (regarded by Eisen as subspecies or varieties) were placed by him in a distinct genus, Argilophilus. There does not, however, appear to me to be any good grounds for placing them in a genus apart from Megascolides. Their anatomy is described in the most detailed fashion in a subsequent memoir (16). (22) Megascolides papillifer (Eiszy). Argilophilus marmoratus papillifer, E1sEn, loc. cit., p. 253. Definition. Lhe the last species, but genital papillae median, intersegmental, one to seven in number. Hab.—San Francisco and southwards. (23) Megascolides australis, McCoy. M. australis, McCoy, Prodr. Zool. Vict. Dec. 1, 1878. Notoscolex gippslandicus, FLETCHER, Proc. Linn. Soc. N. 8. W., ii (2), 1888, p. 603. Definition. Length, 1:23 m.; diameter, 17 mm.; number of segments, 500. Prostomium incomplete, Clitellum, XIZI-XXI. Setae of outer pair further apart than of inner, Male pores occupy position of ventral pair of setae which are absent. Papillae median on XVII/XVIII, XVIL/XIX, and XIX/XX ; the middle papilla carries the male pores, and is more extensive than the others. Dorsal pores commence XV/XVI. Gizzard in V; intestine begins in XIX. Septa IV/XIV thickened. Last hearts in XIII, Nephridia 496 OLIGOCHAETA diffuse, with larger paired tubes posteriorly. Sperm-sacs in XI-XIV on posterior septum. Spermathecae in VIII-IX, with rosette-like caecum. Hab.—Gippsland, Victoria. The reason for FLETCHER placing his species in a different species from McCoy’s was chiefly the inaccurate description given by the latter. It is not, however, clear why FLETCHER should have considered it right to give a new generic name to his species, for the differences which he enumerates are hardly so important as would warrant this course. In any case the description given by FLETCHER is confirmed in almost every particular by SPENCER (1), and the species is the best known of all the members of the genera Cryptodrilus and Megascolides. I deal elsewhere with such anatomical points as are of more than specific importance. The most remarkable feature in its organiza- tion is,in many respects, the extraordinary extension of the sperm-sacs; it is, of course, possible that the two pairs of the thirteenth and fourteenth segments are really egg-sacs; but their large size is against this supposition, and SPENCER distinctly speaks of sperm in their interior. The dorsal blood-vessel is enclosed in a sac which gives off lateral diverticula filled with corpuscles; Deinodrilus is the only other earthworm in which the dorsal vessel is thus enclosed in a pericardium. The development of the nephridia has been studied by VEspovsky (4). (24) Megascolides orthostichon (ScuMaARDA). Hypogaeon orthostichon, ScHMARDA, Neue wirbell. Th. I. ii (1861), p. 12. M. orthostichon, BepDparp, Ann. Mag. Nat. Hist. Feb., 1892, p. 130. Definition. Length, 180 mm.; number of segments, 65. Clitellum, XIV-XVII, complete. Setae in eight equidistant rows. Male porgs correspond to ventral setae, which are wanting. No genital papillae. Gizeard in V. Nephridia diffuse. Sperm-sacs in X-XII, Spermathecae in VIII, [X, with pyriform caecum. Hab—New Zealand. This species is chiefly interesting on account of the fact that it occurs in New Zealand, which is, unlike Australia, not inhabited by many Cryptodrilids; unfor- tunately, my description of its structure is far from being complete, owing to the fact that I had only the type of ScumaRDa, which it was necessary to respect. Hence the definition of this worm is not so satisfactory; it appears, however, to be distinct from any other species of the genus. (25) Megascolides perrieri (Brenna). Plutellus perrieri, Benuan, P. Z. 8., 1892, p. 138. Definition. Length, 50 mm.; diameter, 4 mm.; number of segments, 126. Prostomium DESCRIPTIONS OF GENERA AND SPECIES 497 complete. Clitellum, XIIT-XVIII. Setae distant, ventral closer to each other than dorsal. Male pores between setae 1 and 2. No genital papillae. No dorsal pores. Gizzard in V; no caleiferous glands; intestine begins in XVII. Nephridia paired, alternate, Testes in X. Sperm-sacs in XII. Spermathecae in VI-IX, without diverticula, Hab.— Queen Charlotte's Island, British Columbia, The anatomy of this species is fully illustrated by Bunnam, Genus CRYPTODRILUS, FLETCHER. Syn. Megascolides, SPENCER (in part.). DEFINITION. WNephridia usually diffuse. Last pair of hearts in XII. Spermiducal glands lobate, rarely furnished with penial setae. Male pores upon XVIII. I have already stated the reasons which lead me to divide somewhat differently from either FLeTcHER or SPENCER the total of the species which those authors refer to the two genera Cryptodrilus and Megascolides. It appears to me, after consideration of the various structural features which characterise the family Cryptodrilidae, that the form of the spermiducal glands is rather more important than the variations offered by any other organs. The genus Cryptodrilus as defined here contains species with, and species without, a diffuse nephridial system. It might be held that these species should be referred to different genera; but it is not possible in the present state of our knowledge to discover from the descriptions any other characters which vary coincidently with the nephridia. There are, in fact, only seven species of Cryptodrilus which possess paired nephridia. It is highly possible that Cryptodrilus canaliculatus may not be a Cryptodrilus in the sense that the genus is here defined ; but as no information about the spermiducal glands is to be found in FLETCHER’Ss account of the species it is impossible to be certain. For the present, therefore, and it must be understood that I lay no claim to have devised anything like a permanent arrangement, I shall include within this genus Cryptodrilus all the remaining Cryptodrilids with lobate spermiducal glands opening on to segment xviii. In the accompanying table the species are arranged according to the spermathecae and sperm-sacs, which will perhaps facilitate their identification. In the six species with only one pair of sperm-sacs there are generally, but not always, only one pair of testes and funnels. 38 498 OLIGOCHAETA Spermathecae in viii, ix. . victoriensis . obscurus . hulmei : a - Tneigate } Sperm-sacs in Xii. singularis illawarrae . Mudgeanus simulans . Saccarius } Sperm-sacs in xi, xii. . pygmaeus camdenensis dubius - gravidis Sperm-sacs in ix, xii. . rusticus Spermathecae in v-ix. cameroni Spermathecae, in vii-ix. . mediterreus . canaliculatus . sloanei eas ; teyon Nephridia paired. . manifestus . fletcheri Spermathecae in vi-ix. eannnannnannanananqaananaa (a) With paired nephridia. (1) Cryptodrilus mediterreus, FLETCHER. C. mediterreus, FLercHer, Proc. Linn. Soc. N. 8. W., ii (2), 1888, p. 614. Definition. Length, 110 mm.; diameter, 5 mm.; number of segments, 150. Prostomium incomplete. Clitellum, XII -XVI, complete. Setae of outer couples further apart than of inner. Male pores dorsad of setae 2; median papillae on VI-IX, a pair on X, XI, and on anterior margin of XVIII, XIX, ventrad of male pores. Dorsal pores commence V/VI. Gizeard in V; calciferous glands in X-XIII; intestine begins in XVIII. Nephridia paired and alternate. Last hearts in XIII. Septa, VI/XIII, thickened. Sperm-sacs in XI, XII; spermathecae, VII-IX, caecum minute. Penial setae present, with serrated eatremity, Hab.—Darting river, N. 8. W. This species differs from the remaining forms which are associated with it by the character of their nephridia in having penial setae and in having sperm-saes in x, xii, instead of ix, xii. DESCRIPTIONS OF GENERA AND SPECIES 499 (2). Cryptodrilus canaliculatus, FLercHer. C. canaliculatus, FLETCHER, loc. cit., iii (2), 1889, p. 1534. Definition. Length, 250 mm. ; diameter, 5-5 mm.; number of segments, 265. Prostomium incomplete. Clitellum, XITE-XVIIL, complete. Setae of outer couples widely separated. Male pores on papillae preceded and followed on the same segment by similar papilla, of which there are also a pair on the newt segment. Dorsal pores commence VIIL/IX. Gizeard in V; caleiferous glands in X—XIII, lying below the gut; intestine begins in AVI, Nephridia, paired, alternate. Sperm-sacs in IX, XII; spermathecae in VIT-IX, caeca 2. Penial setae present. Hab—Fortes, N. 8. W. (3) Cryptodrilus sloanei, Fiercuer. C. Sloanei, FLETCHER, loc. cit., p. 1536. Definition. Length, 71 mm.; diameter, 5 mm. ; number of segments, 150. Prostomium nearly complete. Three pairs of caleiferous glands in XI, XII, lying below gut. Last hearts in XTIT. Sperm-sacs in IX, XII; spermathecae three pairs, caeca 2. Hab.—Coona- barabran, N.S. W. It is not stated in so many words that this species has paired alternating nephridia ; I infer, however, from its location in the neighbourhood of C. canaliculatus, and its comparison with this species and with C. mediterreus, that the nephridia are of that kind. (4) Cryptodrilus manifestus, FLetcuen. C. manifestus, FLETCHER, loc. cit., p. 1538. Definition. Length, 70 mm.; diameter, 5-7 mm.; number of segments, 190. Prostomium complete. Clitellum, XIV-XVII, complete. Setae of outer couples further apart than of inner. Male pores ventrad of innermost setae (which appear to be absent?) ; on XVII, XIX, and next three or four segments, papillae. First dorsal pore, VIL/IX. Gizzard in Vi; caleiferous glands in X-XIII; intestine begins in XVI, -Nephridia, paired, alternate. Last hearts in XII. Sperm-sacs in IX, XII; spermathecae in VI-IX, with a single caecum. Hab.—Waterfall, Bulli, National Park, N. 8. W. This species is very near to C. fletcheri, but is distinguished by having four instead of two or three pairs of calciferous glands. 382 500 OLIGOCHAETA (5) Cryptodrilus fletcheri, Bepparp. C. fletcheri, BepparD, P. Z. 8., 1887, p. 544. ? CO. Oxleyensis, FLETCHER, Proc. Linn. Soc., N. 8. W., iii (2), 1889, p. 1537. Definition. Clitellum, XITI-XVII, complete execpt on XVIT. Setae in eight rows, the outer Jurther apart than inner. Male pores on papillae, of which there are also pairs on AVILT, XIX-XXI. Oviducal pore a single ‘stit-like orifice’ Gizzard in VI, VII; caleiferous glands in XI, XII, ventral in opposition. Nephridia paired alternate. Sperm- sacs in IX, XII; spermathecae in VI-IX, with longish caecum. Hab.—Queensland. This species may or may not be identical with C. oxleyensis. There is nothing in FLETcHER'’s description of the latter to militate against their identification; but hig description is incomplete owing to the immaturity of the worms, as is mine in certain points, which ought to have been noticed and recorded. The dorsal pores in C. oaleyensis begin vi/vii. There are three pairs of calciferous glands ventral in position (I figure three but only describe two). (6) Cryptodrilus tryoni, FLErcuer. C. Tryoni, FLETCHER, Proc. Linn. Soc., N.S. W., iv (2), 1890, p. 994. Definition. Length, 325 mm.; diameter, 10 mm.; number of segments, 209. Prostomium incomplete. Clitellum, XIV-XVIII, complete except on ventral surface of XVII. Setae of outer rows remarkably far apart. Gizzard in V; calciferous glands in IX-XIII. Nephridia alternate; last hearts in XII; septa, VI/XIV, thickened. Sperm-sace in IX, XIT; spermathecae three pairs, caeca two. *Penial setae present. Hab.—Milton, near Brisbane. (b) With diffuse nephridia. (7) Cryptodrilus victoriensis (SrenceEr). Megascolides victoriensis, SpENcER, P. R. Soc. Vict., 1892, p. 151. Definition. Length, 3 feet; breadth, 12mm. ,; Prostomium incomplete. Clitellum, XITI-XIV. Setae of outer rows four times as far away from cach other as those on inner, irregular at end of body. Male pores on level of interval 1/2. Genital papillae median on ATII/XIV, XIX/XXII ; in all four. Dorsal pores commence X1/XII. Gizzard in V; no caleiferous glands; intestine begins in XVII. Sperm-sacs im XII; spermathecac, THI, IX, two rosette-like diverticula. Hab.—Tictoria (? as to exact locality). DESCRIPTIONS OF GENERA AND SPECIES 501 (8) Cryptodrilus obscurus (SPENCER). Megascolides obscurus, SPENCER, loc. cit., p. 148. Definition. Length, 425 mm.; breadth, 12 mm. Prostomium incomplete. Clitellum, XTII_-XIX. Male pores on a level with interval between setae 1/2. Genital papillae median unpaired, XIII/XIV, XIX/XX, XX/XXI. Dorsal pores commence V/VI. Gizzard in VI; no calciferous glands, but swellings im XIII-XV. Intestine begins in XVIII. Sperm-sacs in XII ; spermathecae in VIII, IX, each with two small diverticula. Hab — Dandenong Ranges. The testes are only one pair in xi; but there are two pairs of funnels, those of x smaller. (9) Cryptodrilus hulmei (SpEncer). Megascolides hulmei, SPENCER, loc. cit., p. 147. Definition. Length (of an incomplete specimen), 3 ft. 5 in.; breadth, 6 mm. Prostomium emcomplete, Clitellum, XIII-XX. Setae of outer couples slightly further apart than those of inner. Genital papillae unpaired; on XIII/XIV, XVI, XVII, XIX/XXII. Dorsal pores commence VILI/IX. Gizzard in V; no calciferous glands; intestine in XVIL. Sperm-sacs in XII; spermathecae in VIII, IX, with small diverticulum. Hab.— Dandenong Ranges. Here again there is only one pair of testes in xi, but two pairs of funnels. (10) Cryptodrilus insignis (SpENcER). Megascolides insignis, SPENCER, loc. cit., p. 146. Definition. Length, 150 mm.; breadth, 6 mm. Clitellum, saddle-shaped, XII[—XVIILI. Setae of outer rows further apart than those of inner. Posteriorly wider still. Male pores on interval between setae 1/2. Oviducal pores ventral of, and anterior to inner- most setae. Genital papillae white swollen ridges ventrally on XV-XXI. Dorsal pores commence IX/X. Gizeard in VI; vascular swellings in X, XI; small diverticula in XII-XIV ; large calciferous glands in XV-XVII ; intestine begins in XIX. Testes and funnels one pair in XI. Sperm-sacs in XII; spermathecae in VIII, IX, with short diverticulum. Hab.—Dandenong Ranges. 502 OLIGOCHAETA (11) Cryptodrilus cameroni (SPENCER). Megascolides cameroni, SPENCER, loc. cit., p. 144. Definition. Length, 212 mm.; breadth, 12 mm. Prostonium incomplete. Clitetlum, XVI-XXI incomplete, ventral at anterior end. Setae of outer couples further apart than of inner outer setae, wregular on clitellum. Male pores on level of innermost seta, Dorsal pores commence III/IV. Gizeard in V/VI; swellings of oesophagus in VITI-XIV ; intestine begins in XIX. Dorsal vessel double as far as fifth segment, and to end of body. Sperm-sacs in IX, XII; spermathecae in V-IX, with diverticulum half the length of sac. Hab.—Croajingolong. (12) Cryptodrilus singularis, FLErcHer. C. singularis, FLETCHER, Proc. Linn. Soc, N.S. W., iii (2), 1889, p. 1547. Definition. Length, 130 mm.; breadth, 7 mm.; number of segments, 240. Prostomium incomplete. Clitellum, XIII-XVIII, complete. Setae of outer couple further apart than inner. Male pores in line with seta 2. Oviducal pores im front of and ventrad of seta 1. Genital papillae elliptical areas between XVI/XXI. Dorsal pores commence AY/XIT, Gizzard in V; no distinet calciferous glands; intestine begins in XVIII. Last pair of hearts in XII, Septa V/XII thickened. Testes and funnels one pair in AL; sperm-sacs in XII. Spermathecae im VIII, [X, with small diverticulum, Hab.— Burrawang, N. 8. W. Four conspicuous ridge-like folds are described as existing on the floor of the intestine from segment xx-l; there is no typHlosole. (13) Cryptodrilus saccarius, FLETCHER. C. saccarius, FLETCHER, loc. cit., i (2), 1887, p. 951. Definition. Length, 195 mm.; breadth, 12 mm.; number of segments, 290. Prostominm incomplete. Clitellum, XUE-XPUT, complete. Setae in eight rows more or less irregular, inner couple absent on XVIII. Male pores in line with interval between setae 1 and 2. Genital papillae vary; there may be two elliptical papillae between XI/XII and four between XVILI/XIX, and XX/XXIV. Oviducal pores in front of, and ventrad of first seta. Dorsal pores commence X/XI. Gizzard in V; caleyferous glands in IX-XTIIT ; salivary glands in V, VI; intestine begins in XV. Sperm-sacs in XI, XII. Spermathecae in VILL, IX, with small caecum opening dorsal of inner seta. Last hearts in XIII. Hab.—Hornsby, Port Jackson, Springwood, N.S. W. DESCRIPTIONS OF GENERA AND SPECIES 503 FLETCHER describes ‘three’ varieties of this—two in addition to the typical form; the latter are named respectively ‘montanus’ and ‘robustus’; both of these differ in having an additional pair of calciferous glands in viii. They differ also in genital papillae and in size. (14) Cryptodrilus mudgeanus, FLercuer. C. Mudgeanus, FLETCHER, loc. cit., iii (2), 1889, p. 1532. Definition. Length, 58 mm.; breadth, 5-5 mm.; number of segments, 145. Prostomium incomplete. Clitellum, XIII-XVIII, complete. Male pores just dorsad of first seta. Oviducal pores in front of and ventrad of inner setae, Genital papillae elliptical or dumb-bell-shaped elevations between segments (some or all) AVI/XXITII. Dorsal pores commence XI/XII. Gizzard in V; calciferous glands in X-XIIT; intestine begins in XVI, Last hearts in XIII. Sperm-sac in XI, XII. Spermathecae in VIII, 1X, with short diverticulum, opening opposite setae. Hab.—Cuullenbone, near Mudgee, N. 8. W. (15) Cryptodrilus dubius (Bepparp). C. Illawarrae, FLETCHER, loc. cit., p. 1546. Definition. Length, 100 mm.; breadth, 3 mm.; number of segments, 270. Prostomium incomplete. Clitellum, XIV-XVII, complete. Setae of outer couples twice as far apart as those of inner, Male pores im line with interval between setue 1 and 2. Oviducal pores to inside of and im front of inner setae. Genital papillae a ridge connecting male pores. Dorsal pores commence X/XI. Giezard in V; no distinct calciferous glands ; intestine begins in XVI. Last hearts in XII. Sperm-sacs in IX, XII. Spermathecae in VIII, IX, each with two short diverticula, opening just dorsad of inner seta. Hab.—Itlawarra, N.S. W. I have been compelled to change the name of this species as there is another, C. illawarrae; the two species were, of course, assigned by FLETCHER to different genera. There seem to be possibly salivary glands of nephridial nature in segments v-vii. FLErcHER describes a variety with an additional pair of papillae between xvi/xvii from Blue Mountains. (16) Cryptodrilus illawarrae (FLErcHER). Megascolides (Notoscolex) Illawarrae, FLETCHER, loc. cit., p. 1523. Definition. Length, 200 mm.; breadth, 7 mm.; number of segments, 395. Prostomium incomplete. Clitellum, XIII-XXII, complete. Setae of outer row sinuous after segment 504 OLIGOCHAETA XV, inner couple wanting on XVIII. Male pores on level with interval between inner setae. Dorsal pores commence XI/XII. No distinct caleiferous pouches. Last pair of hearts in XII, Testes and funnels in XI; sperm-sacs in XII. Spermathecae i VIII, IX, with a single rosette-like diverticulum, opening in line with a little ventrad of first seta, Penial setae present, Hab.— Mount Kembla, Illawarra, N. 8. W. In the points not mentioned in the above, the species is stated by FLETCHER to agree with C. camdenensis. (17) Cryptodrilus pygmaeus (FLETcuHER). Megascolides (?) (Notoscolex) pygmaeus, FLETCHER, loc. cit., p. 1525. Definition. Length, 85 mm.; breadth, 4 mm.; number of segments, 200. Prostomium incomplete. Clitellum, XIV-XIX. Setae of outer couples further apart than of inner. Male pores in line with interval between ventral setae, behind each a pore. Genital papillae a median ridge between XIX/XX, and XX/XXI. Dorsal pores commence XI/XII. Calciferous glands one pair im XIT, XIII; salivary glands (nephridial) in V, VI; intestine begins in XV. Last pair of hearts in XII. Sperm-sacs in XI, XII. Spermathecae in VIII, IX, with a small diverticulum. Hab.—Ilawarra. (18) Cryptodrilus rusticus, FLercuer. C. rusticus, FLETCHER, loc. cit., i (2), 1887, p. 570. Definition. Length, 190 mm.; diameter, 7 mm.; number of segmeuts, 250. Prostomium incomplete. Clitellum, XII[-XVII, complete. Male pores at the entremity of a dumb- bell-shaped papilla of which there are others on XVI/XVII, anil XIX/XX, XX/XXI. Setae of dorsal pairs further apart than of ventral. Dorsal pores commence XIII/XIV. Gizzard im V; intestine begins on XVIII. Last hearts in XI. Septa VII/XII thickened. Sperm-sacs in IX, XII; spermathecae in VIII, IX, two or three rudimentary caeca. Hab.— Burrawang, N. 8. W. (19) Cryptodrilus camdenensis (FLETcHER). Notoscolex Camdenensis, FLETCHER, loc. cit., p. 546. Definition. Length, 148 mm.; diameter, 9 mm.; number of segments, 220. Prostomium incomplete. Clitellum, XIV-XXILI, incomplete ventrally. Setae of outer rows further apart than of inner. Male pores on line with interval between seta 1 and 2 (the setac wanting). Ovilucal pores ventrad of inner setae. Dorsal pores commence VIII/IX. DESCRIPTIONS OF GENERA AND SPECIES 505 Gizzard in VI; caleiferous glands in XIV-XVI 3 Intestine begins in XVIII. Septa VI/XIV thickened. Last hearts in XIII. Sperm-sacs in XI, XIT; spermathecae tn VILL, IX, with small lobulate caecum. Hab.— Burrawang, N. 8. W. It is mentioned that the intestine is coiled in a corkscrew fashion, when the worm is contracted. (20) Cryptodrilus grandis (Firrcuer). Notoscolex grandis, FLETCHER, loc. cit., p. 551. Definition. Length, 760 mm.; diameter, 11 mm.; number of segments (?). Prostomium encomplete. Clitellum, XIII-~XIX, complete. Setae in eight rows as im preceding species. Male pores on two papillae which dovetail in between the ends of two papillae formed by narrow transverse ridges on XVIIL and XIX. Dorsal pores commence VIII/IX. Gizzard in VI; no calciferous glands; intestine begins in XVIT, Septa VI/XIII are thickened. Sperm-sacs in IX, XII; spermathecae in VILL, [X, with small diverticulum. Hab.—Burrawang, N. 8. W. (21) Cryptodrilus simulans, FLEercuer. C. simulans, FLETCHER, loc. cit., iv (2), 1890, p. 998. Definition. Length, 108 mm.; diameter, 5 mm.; number of segments, 220. Prostomium encomplete. Setae of outer couples further apart than of inner. Male pores corresponding eaterval between setae 1 and 2; on a ridge-like swelling which is repeated on VII and XIX. Dorsal pores commence X/XI. Gizzard in V; caleiferous glands in XIV, XV ; intestine begins in XVII. Last hearts in XII. Sperm-sacs in XT, XII; spermathecae im VIII, IX, with rosette-like caecum. Penial setae present, not ornamented. Hab.— Bulli, Mawarra, N.S. W. Genus MICRODRILUS, Brepparp. DEFINITION. Male pores on XVII. Spermiducal glands tubular with penial setae. Nephridia diffuse. Gizzards, two. ‘ This genus is very near to Digaster. The principal reason which leads me to separate the two is the fact that the male pores of the present genus open on to segment xvii instead of xviii. Another feature which may perhaps be of generic value is the fact that only one of the three pairs of calciferous glands opens into the oesophagus; the other two open into it. This peculiarity of the calciferous gland has been hitherto 3T 506 OLIGOCHAETA only found in the genera Allolobophora and Lumbricus. I have commented elsewhere on the curious points of similarity between this genus and Benhamia. Microdrilus saliens, BepDarp. M. saliens, BEDDARD, P. Z. 8., 1892, p. 683. Definition. Length, about 25mm. Clitelium, XIIT-XIX, complete except on XIX. Calciferous gland on XV, XVI, XVII, the anterior pair only open into gut. Setae paired. Dorsal pores commence IV/V. Oviducal pores to inside of ventral setae. Spermathecae two pairs with a single caecum. Penial setae undulated at extremity with fine notches at each bend. Hab.—Java, Penang. This species when alive showed the extreme agility of movement so characteristic of the genus Perichaeta. The spermiducal glands open independently of the sperm- ducts on to a semicircular elevation with a pore at each end; these large papillae are very conspicuous, and are so arranged that the straight side of each is opposed to that of the other. The sperm-duct is invested for the last two segments of its course by a thick muscular coat as in Benhunvia crassa. The intestine begins in segment xviil. Genus GORDIODRILUS, BEepDaRrp. DEFINITION. Small slender Oligochaeta with paired setae. Nephridia paired. Gizzard generally absent; a single median"(rarely paired) ealciferous gland in IX of peculiar structure. Hearts in X, XI. Spermiducal glands, two pairs (rarely one pair) with epithelial lining only one cell thick, opening in consecutive segments. Sperm-duct pore on XVIII (or XX) independent of spermiducal glands. Spermathecae two pairs (rarely one or absent) in VIII, IX, with at most rudimentary diverticula. Septal glands present in V-—VII or VIII. This genus is, with the exception of Gordiodrilus dominicensis, confined to tropical Africa, preponderating greatly on the west side of the continent. Though apparently closely related to Ocnerodrilus and Pygmaeodrilus, it is to be distinguished from both by the peculiar structure of the calciferous gland, which is moreover, excepting in G. robustus, unpaired. The separate aperture of the sperm-duct is another point which separates this genus from the other two, as is also its position (on the eighteenth instead of the seventeenth segment). DESCRIPTIONS OF GENERA AND SPECIES 507 There is a greater range of variation among the species of this genus than is the case with the related Ocnerodrilus. The four species, G. elegans, G. ditheca, G. dominicensis, and G. zanzibaricus, form a distinct group, characterized by their small size, by the absence of a gizzard, and by the fact that the spermathecae do not communicate with the exterior by a long duct. G. robustus is a stouter species, though small, with paired calciferous glands, with a well-developed gizzard, and with spermathecae with a long duct. The most abnormal species is, however, G. tenuis, which has some claims to be placed apart in a separate genus. It is extraordinarily long, and the ventral setae, like those of Megachaeta, are very much larger than the dorsal; the pores of the spermiducal glands are much further back than in the other species, and there is but a single pair of testes. G. robustus serves to connect the genus Gordiodri/us with the nearly-related Ocnerodrilus. As in Ocnerodrilus the ventral setae, near to which the spermiducal glands open, are present or absent. In G. tenuis these setae are present and unaltered ; in G. elegans they seem to be completely absent; in G. zanzibaricus one of the two setae of the ventral pair only is absent, the others being present and unaltered. The amount of varia- tion in the position of the male pores is unusual. In G. robustus and G. zanzibaricus the pores of the spermiducal glands are upon segments xvii, xviii; in G. elegans they have moved a segment further back and are upon xviii, xix’, G. tenuis is in this, as in other respects, most abnormal; the pores in question are in that species upon segments xx and xxi. The various pores connected with the male efferent apparatus open on to a pronounced ridge, one on either side, with an undulating outline, being deeper at the two ends than in the middle. The two ridges seem to join in front and behind, forming thus a sucker-like structure. (1) Gordiodrilus tenuis, BrpDArp. G. tenuis, Bepparp, Ann. and Mag. Nat. Hist., July, 1892, p. 75. Definition. Length, 90 mm.; diameter, 1mm. Ventral setae, present on genital segments, four times the size of lateral setae. Clitellum, XIV-XXVII, saddle-shaped. Spermiducal gland pores on XX, XXI, behind setae; male pore on XXI, in front of setae. Septa, V/XIL, thickened. Testes, one pair in XI; sperm-sacs in X-XIII. Spermathecae, two pairs, with long duct. Hab.—Assaba, W. Africa. 1 In my paper upon this genus there is unfortunately some little confusion as to this matter; the segments are rightly stated on one page, and misstated on another. oy2 508 OLIGOCHAETA The appearance of this worm during life was something like that of a Lumbriculid ; it was extraordinarily long and thin, and fairly. active in its movements. The large ventral setae can be easily felt when the worm is handled; under those circumstances it adheres to the finger by the setae. Its superficial resemblances to Megachaetau appear, from MICHAELSEN’s description of the latter, to be not inconsiderable. Judged by external characters it would be very probably referred to that genus. It has a milky-white appearance owing to the presence of a great quantity of coelomic corpuscles. The ventral setae, though so much larger than the lateral, are not themselves equisized ; the innermost of the two is distinctly larger than the outermost setae of the pair. The nephridia, which seem to commence in the sixth segment and open in front of the lateral setae, are covered with an abundant coating of peritoneal cells. The intersegmental septa are very much more extensive than is the diameter of the body; hence it results that they are placed within each other like a series of very deep cups, a common arrangement among worms but rather exaggerated here. (2) Gordiodrilus robustus, BepDarb. G. robustus, BEDDARD, loc. cit., p. 82. Definition. Length, about 32 mm.; number of segments, go. Setae of segments V—-VII larger ; ventral setae of segments XII and XIII very large, present on genital segments. Clitellum, XIII-XVII, saddle-shaped. Spermiducal gland pores upon XVII, XVIII; male pores upon XVIII. Gizzard in segment VIII; caleiferous glands paired. Septa separating segments V/VIII, much thickened, those between VIII/XII slightly thickened. Snermathecae in VII, VIIT; duct long and slénder. Hab.—Lagos. This species is furthermore marked by an oval median papillae upon segment xix. The spermathecae have thin walls and were found to be much crumpled in sections. (3) Gordiodrilus elegans, BEDDARD. G. elegans, BeDDARD, loc. cit., p. 84. Definition. Length, about 40 mm. Setae of ventral pairs absent on segments XVIII, XIX. Clitellum, XITI-XVIII, saddle-shaped. Spermiducal pores on XVIII, XIX ; male pores exactly between them. Septa, V/X, thickened. Sperm-sacs in IX-XIL. Spermathecae in VIIT and IX, each with two rudimentary diverticula ; the duct is short. Hab—Lagos. The septal glands occupy segments v—vii. The nephridia of this species commence in the fourth segment; after the first few DESCRIPTIONS OF GENERA AND SPECIES 509 pairs (beginning in the thirteenth segment in one specimen, in the nineteenth segment in another) they are coated with a thick layer of peritoneal cells. The spermathecae open between vii/viii and viii/ix; in one individual they both lay in the eighth segment. The duct is quite short, and ensheathed in a thick muscular layer. (4) Gordiodrilus ditheca, Bepparp. G. ditheca, BEDDARD, loc. cit., p. go. Definition. Length, about 40mm. Clitellum, XIII-XVII. Spermiducal pores on XVIII. Spermathecae in VII, without diverticula Hab—Lagos. This species only differs from the last in the single pair of spermiducal glands and spermathecae. (5) Gordiodrilus dominicensis, Bepparp. G. dominicensis, BEDDARD, loc. cit., p. 91. Definition. Length, 26 mm.; diameter, 11 mm.; number of segments, 60. Setae of ventral pairs absent upon eighteenth and nineteenth segments. Spermiducal pores on XVIII, XIX. Septa VI/IX specially thickened ; those between V/VI and IX/X tolerably strong. Spermatheca absent. Hab.— Dominica, W. Indies. The principal distinguishing mark of this species is, of course, the absence of the spermathecae. It is, however, just possible that the spermathecae were not yet developed, as the worm had -no clitellum. The septal glands extend back as far as the eighth segment. The nephridia commence in the fifth segment; from the tenth segment onwards the nephridia are invested with a mass of clear peritoneal cells. (6) Gordiodrilus zanzibaricus, Bepparp. G. zanzibaricus, BreppaRD, Q. J. M. 8., xxxvi, 1894, p. 252. Definition. Length, 25 mm. Clitellum, XUI-XIX. Ventral setae of segments XVII, XVIII, represented by one seta only. Spermiducal pores upon XVII, XVIII. Septa between segments V/XI thickened, particularly those between VI/IX. Sperm-sacs in XII; sperm-masses in X, XI. Spermathecae in VII, IX, with short muscular duct. Hab.— Zanzibar. The septal glands of this species are well developed, and extend as far back as the seventh segment, there being traces of a pair of these glands in the eighth. 510 OLIGOCHAETA The nephridia commence in the fifth segment; in and after the tenth they are invested by a layer of clear peritoneal cells. The ventral surface of the eighth segment, and the anterior half of the ninth, are modified, the cells of the epidermis being tall and glandular; this layer of cells is not interrupted in the middle ventral line. Genus OCNERODRILUS, EISEN. Syn. Pygmaeodrilus, MICHAELSEN. DEFINITION. Small, often aquatic, worms. Setae paired, sometimes absent upon segment XVII, upon which sperm-ducts open. Spermiducal glands lined with @ single layer of cells. Gizzard absent; calciferous glands paired in IX. Nephridia paired. Sperm-ducts open in common with spermiducal glands. For a long time this genus was only known by a single species, Ocnerodrilus occidentalis, described some years ago by Eisen (9); in 1891 I described a second species, O. eiseni (20); more recently still (1), Eisen has published a paper containing an account of eight new forms, while MicHAarLsen and I have described several African species, formerly relegated to the genus Pygmaeodrilus. We are, therefore, in possession of a considerable amount of information about this genus. The species of the genus are all of small size; they are partly aquatic, but usually terrestrial in habit. The genus is easily separable from Gordiodrilus, on account of the paired diverticula which have a different structure from those of the latter; another important difference is in the fact that the sperm-duct pores are always on the seventeenth segment in the present genus, and usually on the eighteenth segment in the genus Gordiodrilus, and that the sperm-ducts open by the same pore as the spermiducal glands; the calciferous glands are, however, paired in G. robustus ; another intermediate form is O. limicola, where there are also two pairs of spermiducal glands on exactly the same segments as those on which they occur in G. robustus; but in O. linvicola the sperm-ducts open into the first pair of these glands, and the similarity to Gordiodrilus is thus reduced to the mere doubling of the spermiducal glands, which is of no more importance than the fact of the reduction of the spermiducal glands to a single pair in G. ditheca. The ten species of Ocnerodrilus differ in four principal characters, besides others of less importance. There are considerable variations in the condition of the ventral pairs of setae in DESCRIPTIONS OF GENERA AND SPECIES 511 the seventeenth segment ; indeed, every possible variation occurs. This segment is the one which bears the male pores. In the type-species of the genus, O. occidentalis, and in one other, 0. limicola, both setae of the pair are present and unchanged; this may be fairly regarded as the primitive condition. The next stage is shown in those species in which one or other of the two setae have disappeared. Finally, the majority of the species (five) are entirely without the ventral pairs of setae. Eisen considers that the genus is naturally divisible into two groups; in one of these the lower end of the sperm-duct is enveloped by a thickish muscular sheath ; in the other there is no such sheath. The former state of affairs characterizes these species; the character is a peculiar one, and is met with in other worms belonging to different families ; it may be noted that all the species, viz. O. agricola, O. rosue, and O. contractus, which present this structural peculiarity, have no ventral setae upon the seventeenth segment. O. limicola is alone in possessing two pairs of spermiducal glands. Though in this character the species in question agrees with the nearly related genus Gordiodrilus, it must not be forgotten that an important difference between the two is the fact that in Ocnerodrilus the sperm-ducts open in common with the spermiducal gland and on to the seventeenth segment. The spermathecae (of which there is never more than one pair) are nearly always in the ninth segment; in O. ezseni, however, they are in the eighth segment, and O. occidentalis is entirely without these organs. A fifth point in which the species vary is in the number of the hearts; in the great majority there are only two pairs of these; but O. lemicola and O. hendrici have an additional pair in the ninth segment, which, in the latter species at any rate, is a pulsating vessel like the two which follow. Of minor importance, as it appears to me, are the relative size and the lobation of the septal glands, upon which Eisen is inclined to lay considerable stress ; of less importance still, perhaps, are the relative size and form of the sperm-sacs, where these are—and this applies to the majority—four pairs in segments ix-xi. The degree of sexual maturity would surely be an important factor in causing differences of this kind. The clitellum too shows differences in extent. One species, 0. lacwwm, differs from the rest in having dorsal pores (at least MicHAELSEN has not mentioned them in any species): in the single pair of testes: in the absence of diverticula to the spermathecae: in the presence of gizzards, and in the saddle-shaped clitellum. On the other hand, it presents the following characteristic features of the genus; in the male pores being on the seventeenth segment: in the fact that the sperm-duct is enveloped in a muscular sheath: in 512 OLIGOCHAETA the existence of a single pair of spermathecae in the ninth segment, and in the single pair of calciferous glands in the same segment. Pending further information about the lower Cryptodrilids of Africa, I retain it in the same genus as the species described by MIcHAELSEN. (1) Ocnerodrilus occidentalis, E1sen. O. occidentalis, EiszN, Nova Acta Reg. Soc., Upsala, x (3), 1879, p. 1. Definition, Length, 15 mm. Clitellum, XIII-XX. Setae not absent from segment XVII. Testes only one pair (in X); sperm-sacs only one pair (in XI). Spermiducal glands very ‘long reaching to XXVI. Spermathecae absent. Hab.—Fresno, California. (2) Ocnerodrilus eiseni, Bepparp. O. Hiseni, BreppARD, Trans. Roy. Soc., Edinb., 1890, p. 563. Definition. Length, 25 mm. Clitellum, XITI-XVII. Ventral setae of segment XVII wanting. Spermiducal glands slightly coiled extending through three segments. Spermathecae in VII, Hab.— British Guiana, (3) Ocnerodrilus beddardi, Etsev. O. Beddardi, Eisen, Proc. Cal. Ac. Sci., 1892, p. 230. Definition. Length, 40 mm. Clitellum, XITI-XIX. Inner setae of ventral pair of segment XVII wanting. Septa begin IV/V ; septa separating V/IX, much thickened. Septal glands in V—VIII, last pair small, the largest in V. Hearts in X, XT, arising Jrom supraintestinal vessel. Nephridia commence in IV, the four anterior being small and comparatively rudimentary. Spermiducal glands small only catending through two or three segments. Spermathecae in IX with numerous rudimentary diverticula at free end. Hab— Baja California, near San José del Cabo. (4) Ocnerodrilus guatemalae, Etsen. O. guatemalae, KIsEn, loc. cit., p. 249. Definition. Length, 40 mm. Clitellum, XIV-XVIII. Outer setae of ventral pair of segment XVII wanting. Septal glands of V largest, those of VII and VIII small and nearly equisized, Spermiducal gland confined to a single segment. Spermathecae very smalt, Hab—Guatemala, in soit. In the characters not mentioned above the present species agrees with 0. beddardi. DESCRIPTIONS OF GENERA AND SPECIES 513 (5) Ocnerodrilus sonorae, EIsEn. O. sonorae, EISEN, loc. cit., p. 251. Definition. Clitellum, XIV-XVII. Outer setae of ventral pair of segment XVII wanting. Septat glands in V-VILL, nearly equal in size, slightly diminishing from before backwards. Spermiducal gland confined to two segments, the muscular part not narrower than the glandular, Spermathecae without differentiated muscular duct, Hab.—Sonora, Mexico ; in moist soil near irrigation canals. , (6) Ocnerodrilus hendriei, E1sen. O. Hendriei, Eisen, loc. cit., Pp. 252. Definition. Length, 13 inch by 3 line. Clitellum, XIII-XVIII. Ventral pair of setae on XVII wanting. Septal glands of V larger than VI; those of VII and VIII very small and equisized. Spermiducal glands occupy about two segments. Spermathecae in IX very small, Hab.—Saint Tomas, Guatemala ; on the road after rain. (7) Ocnerodrilus limicola, Etsen. O. limicola, E1sEn, loc. cit., p. 254. Definition. Cliteldum, XUEXIX, Ventral setae of segment XVII present. Septal glands of V slightly larger than the following pairs; those of VIII the smallest. Two pairs of spermiducal glands in XVII, XVIII, the former, as usual, connected with sperm~ duct. Spermathecae in IX very small. Hab.—Guatemala ; in mill pond. It is not quite certain from E1sen’s description whether the ventral setae of xvii are or are not missing; in the description of the species they are said to be wanting once (p. 255), and on the next page to be generally present; on p. 275 they are again said to be wanting, and on the ‘Table of Species’ (facing p. 282) to be present. (8) Ocnerodrilus rosae, EIsEn. O. Rosae, E1gen, loc. cit., p. 258. Definition. Length, 1 inch by % line. Chitellum, XIMI-XVIIL. Ventral setae of XVII wanting. Septal glands of V hardly larger than of VI. Intestine begins in XIII. Spermiducal glanis slender and long, the muscular part nearly half as long as glandular. The sperm-ducts are ensheathed near to their opening with muscular fibres. The 3U 514 OLIGOCHAETA spermathecae are long and cylindrical in IX. Hab.—San Antonio, Guatemaia ; under damp moss at springs. (9) Ocnerodrilus contractus, Erszy. O. contractus, ErsEn, loc. cit., p. 262. Definition. Clitellum, XIII-XVIII. Ventral setae of segment XVII wanting. Septal glands of V equal in size to those of VI, which is largest of four; that of VIII very small. Spermiducal gland long; glandular part 1% times as long as muscular part. The sperm-ducts are ensheathed near to opening with muscular fibres, Spermathecae not so large as that of O. rosac, but larger than iz O. hendriei iw LX. Hab,— Guatemala ; im pools. (10) Ocnerodrilus agricola, EIsEw. O. agricola, HEIsEn, loc. cit., p. 265. Definition. Clitellum, XUE-XVHL. Septal gland of V larger than that of VI;- gland of VIILT smallest. Ventral pair of setae in segment XVII wanting. Spermiducal glands extending as far back as segment XXVIII; glandular part four times and more the length of muscular part. Sperm-duct enveloped terminally by muscular fibres. Spermathecae globular with muscular duct in IX. Hab.—Guatemala ; in moderately dry soil. (11) Ocnerodrilus quilimanensis (MicuazLsEn). Pygmaeodrilus quilimanensis, MICHAELSEN, JB. Hamb. wiss. Anst., vii, 1890, p. 12. e Definition, Length, 38 mm.; diameter, 1-5 mm.; number of segments, 110. Clitellum, AIV-XVI, complete. Gizzard absent (2); intestine begins gradually in segment XII. Testes, two pairs; sperm-sacs in IX, XIT. Spermiducal glands open into a terminal muscular sac, into which the sperm-duct appear to open. Spermathecae with a circle of minute diverticula. Hab—Quilimane, East Africa. (12) Ocnerodrilus bukobensis (MicHartsen). Pygmaeodrilus bukobensis, MICHAELSEN, loc. cit., 1892, ix, 2, p. 4. Definition. Length, 120 mm.; diameter, 2 mm.; number of segments, 120. Clitellum, ATII-XVIIT, complete. Gizeard absent. Testes, two pairs; sperm-sacs in IX, XII. Spermathecae with two or four large diverticula. Hab.—Victoria Nyanza, near Bukoba, This species is also to be distinguished from the last by the near approximation DESCRIPTIONS OF GENERA AND SPECIES 515 of the spermiducal gland pores; there seems to be no muscular sac into which these open. There are papillae, one pair in front of and to the outside of the male pores, the second pair in a corresponding position behind the male pores. The sperm-ducts open independently of the spermiducal glands a little to the outside of them. (13) Ocnerodrilus affinis (Micuaztsey). Pygmaeodrilus affinis, MICHAELSEN, loc. cit., p. 6. Definition. Length, 60 mm.; diameter, 1-5 mm.; number of segments, 106. Clitellum, XIII-XVIII, complete. No gizzard. Spermathecae single and median, with four diverticula. Hab.—Victoria Nyanza, near Bukoba. The genitalia of this species appear to be like the last with the exception of the points mentioned in the above diagnosis, but they were not in a good state of preservation. The thick muscular duct of the spermathecae shows signs of a division into parts. There are four papillae, one pair in front and one behind male pore, on level with ventral setae. (14) Ocnerodrilus lacuum (BeppDazD). Pygmaeodrilus lacuum, BEDDARD, Q. J. M. S., xxxiv, 1893, p. 259. Definition. Length, about 25 mm.; number of segments, about 120. Dorsal pores present. Clitellum, XII-XXVI, saddle-shaped. Ventral setae of segment XVII absent. Septa, V/X, thickened ; septal glands well developed. Gizzards, two in VI, VII; intestine begins in XII, Nephridia commence in segment VI. Testes, one pair in XI; sperm-sacs wm XII. Sperm-ducts open im common with spermiducal gland, uniting just at pores. Spermathecae in IX, without diverticula. Hab—Lagos, West Africa. This species appears to possess no papillae. The above description will show that there is no danger of confusing this species with the others. The living worm was very slender and largely of a chalky-white colour, caused by numerous coelomic corpuscles. The spermiducal glands (at any rate of one example) were very long, and folded extending through six or seven segments. The ventral setae of segment Xvili are absent. Genus NANNODRILUS, BEDDARD. DEFINITION. Small worms with paired setae. Nephridia paired. Gizzard rudi- mentary. Calciferous gland in IX. Spermiducal glands lined by a single layer of cells; posterior of two pairs open on each side into a bursa copulatrix, which 3U2 516 OLIGOCHAETA opens on to a penis, and which also receives sperm-ducts. On segment in front (XVII) open anterior pair of spermiducal glands. Nannodrilus africanus, BeppDARD. N. africanus, BeDDARD, P. Z. S., 1894, p. 388. Definition. Length, about 2 in. Clitellum, XITI-XVII. Septa, V/IX, thickened. Rudi- mentary gizzards in VIL, VIII. Nephridia commence in V, without end sac. Last heart im XI. Spermathecae, one pair in: VII, without diverticulum. Hab.—West Africa ; aquatic. Famity ACANTHODRILIDAE DEFINITION. Large or small Oligochaeta, usually terrestrial, occasionally aquatic, in habit. Setae, 8, 12, or numerous upon each segment of the body. Male pore upon segment XVIII; pores of spermiducal glands upon segments XVII and XIX!. The latter are tubular structures, generally accompanied by penial setae. Spermathecae, nearly always two pairs in segments VIII and IX with diverticulum or diverticula. Anatomical characters. * The Acanthodrilidae are of various sizes; they range from 29 mm. to several feet in length. They have all of them a prostoniiwm, which may be either simply a prolongation of the buccal segment, or may be received into an excavation of the anterior margin, or may be, in addition, continued on to the buccal segment by grooves which are in many cases (e.g. Acanthodrilus novae-zelandiae) prolonged as far as the posterior limits of that segment. The setae are never ornamented at the extremity’, as in the Geoscolicidae; they are usually eight in each segment; but in Deinodrilus there are twelve to each segment, and in the genus Plagiochaeta 25-27 couples of setae. When the number of setae is restricted to eight, these may be arranged in closely approximated couples (e.g. A. wngulatus), or may be somewhat separated from each other, as in Octochaetus Diplocardia is the only certain exception to this statement. ? Except in the case of Benhamia togoensis. DESCRIPTIONS OF GENERA AND SPECIES 517 multiporus. Finally, we have in A. capensis an intermediate condition: the setae are closely approximated in the front region of the body and more separated behind. In the genus Octochaetus, as in Acanthodrilus, the ventral setae of the eighteenth segment are present; the ventral setae of the seventeenth and nineteenth segments are wanting, being replaced by the penial setae. 0. ant- arcticus and O. multiporus! show an interesting inter- mediate condition; the setae of the eighteenth segment are present, the male pore lying just dorsad of the outermost of the two. On the seven- teenth and nineteenth seg- ments the penial setae occupy the place of the outer of the two setae of each ventral pair, but the inner setae of the ventral pair are present and - apparently unmodified. The penial setae are rather short and often, at any rate, less curved than is usually the case with these setae. The setae of these genital segments are in a simple condition which nearly reproduces the state of affairs in such a form as Gordiodrilus. The genus Kerria, which is in some respects the simplest Acanthodrilid, has no penial Fig. 45. GENITAL SEGMENTS OF A NUMBER OF ACANTHODRILIDS. A. Octochaetus antarcticus. B. Acanthodrilus capensis. C. Benhamia. D. Acanthodrilus smithii. E. Acanthodrilus novae-zelandiae. ¢ Male pore. At. Spermiducal gland pores connected by a groove. Penial setae omitted in D and E. setae but only the ordinary and unmodified setae of those segments. O. antarcticus is only just removed from that simple condition, which is possibly characteristic of Rosa’s A. spegazzinii, and is a reason for placing that species in my genus Kerria. ' I erroneously stated in my original description of this worm (8) that penial setae were absent. 518 OLIGOCHAETA In the genus Octochaetus the male pores are always outside of the ventral setae; this is not always the case with Acanthodrilus; A. falclandicus is like Octochaetus in this respect, but A. novae-zelandiae has the male pores between the two setae of the ventral pair; the conspicuous groove which in this and in other species connects the two atrial pores of each side of the body, and bears the sperm-duct-pore in its course, passes exactly half way between the closely approximated setae of the ventral pair (see woodcut, fig. 45). The clitellum is frequently saddle-shaped, that is, the thickened epidermis is confined to the back and sides of the segments upon which the clitellum is developed, and does not extend on to a ventral area bounded by the ventralmost setae of each side; this state of affairs is, however, not always found upon the first few segments of the clitellum; it commonly commences with the segment just in front of that bearing the reproductive pores. The clitellum is very variable in extent, in Deinodrilus benhami it is limited to three segments (xiv-xvi); in Trigaster lankestert segments xiii-xl constitute the clitellum; the most usual segments upon which it is developed are xiii-xvii. Dorsal pores are usually present; but in a few species (e.g. A. georgianus) they are entirely absent. The position of the first pore is naturally variable. In mature, and generally also in immature, Acanthodrilidae, the male genital pores are extremely conspicuous; these pores are nearly invariably—most exceptions that have been described will probably prove in the long run not to be exceptions—upon the seventeenth and nineteenth segments; these apertures are those of the spermi- ducal glands, and they are generally situated upon prominent papillae, corresponding in position to the ventral setae; on the eighteenth segment are the minute pores of the sperm-ducts. Through the spermiducal gland-pores protrude the penial setae, when these are present. A groove always connects the two pores of each side of the body. Quite exceptionally, Neodrilus monocystis has only a single pair of spermiducal gland-pores; these are on the seventeenth segment; a groove connects the pore of each side with the sperm-duct pore on the eighteenth segment. The spermathecal pores in almost every species lie upon the boundary-line between segments vii/viii, viii/ix, and correspond in position to the pores on xvii, xix; in their neighbourhood there are occasionally papillae, but the presence of such papillae is not at all characteristic of the family, as it is of the family Perichaetidae. The oviducal pores lie upon the fourteenth segment; there are only one or two species (e.g. Benhamia bolavi) in which the female pore is single and median as it is in the genus Lerichaeta (s.s.). The alimentary canal presents the same subdivisions as in other earthworms. DESCRIPTIONS OF GENERA AND SPECIES 519 The buccal cavity is followed by an oesophagus which passes into the intestine at about the eighteenth segment, but the exact position varies. The oesophagus is differentiated into a gizzard in most Acanthodrilidae; in all the members of the genus Benhkamvia and in Diplocardia there are, indeed, two separate gizzards; and in T'rigaster there are no less than three of these organs. In a few species, particularly those which are aquatic in habit, the gizzard is absent; in some of these species, however, the gizzard, although it appears on a superficial inspection to be completely unrepresented, can be recognized in longitudinal sections ; it is so, for instance, with A. falclandicus (described by myself as A. georgianus). The gizzard in all the Acanthodrilidae lies well forward, even so anteriorly as the fifth segment (e.g. Octochaetus huttont) ; it may or may not be confined to a single segment. Calciferous glands are very common, but not universal, in the family. They are particularly prone to be absent in the genus Acwnthodrilus itself; thus they are said to be absent in A. pictus; in the genus Benhamia, on the other hand, they appear to be invariably present, and to the number of three pairs; in Benhamia, moreover, the calciferous glands seem to be more independent of the oesophagus than is the case with other Acanthodrilids; this, however, is not much more than an appearance; for in A. dissimilis, for example, transverse sections show that the calciferous glands are really quite distinct from the oesophagus, but, on account of their large size, they completely encircle the gut, and, on dissection, seem to be merely local thickenings of the oesophagus. The calciferous glands lie rather far back as compared with many other earthworms, such as Pontoscolex; in Benhamia they occupy segments xiv, xv, xvi, very often, if not always; in O. multiporus the last pair is even in segment xvii or xviii. For the details of the numbers of pairs, and their position, in the different species, reference must be made to the descriptions of the species. There is nothing characteristic about the structure of these organs in the present family. The intestine begins as early as the sixteenth segment in Plagiochaeta, but usually it does not commence before the eighteenth segment. In Plagiochaeta there is, according to BENHAM, no typhlosole; in other species the typhlosole is variable in its development; in O. multiporus the typhlosole is large and trifid in transverse section; in A. novae- zelandiae the typhlosole is inconspicuous ; in Benkamia there is a subsidiary typhlosole, one on either side of the main typhlosole. Plagiochaeta is almost unique among the Oligo- chaeta for the fact that the intestine is spirally twisted. The intestine is totally without caeca or glands of any description. The nephridia in this family are sometimes paired and sometimes diffuse; in the restricted genus Benhamia they are always diffuse; so too in Octochaetus ; 520 OLIGOCHAETA but in Acanthodrilus the nephridia are as invariably paired. It is, indeed, upon these characters that the genera of the Acanthodrilidae are distinguished. In the genus Acanthodrilus the paired nephridia in a few species (e.g. A. novae-zelandiae and A. dissimilis) alternate in position from segment to segment; this is also found in Plagiochaeta ; the alternation of the nephridia is coupled with a difference in structure; I have, however, already gone into this matter at some length (p. 38), and need not, therefore, return to it again. It may, nevertheless, be pointed out that it is only among the New Zealand species that this peculiarity is met with. Where the nephridia are diffuse, the external apertures are, of course, not visible; they are too minute to be detected by the unarmed eye. There is generally an accumulation of nephridia in the anterior segments; in Octochaetus, and doubtless in other species, when they come to be better known, the same thing will be found; the anterior nephridia form a compact mass which opens by a duct into the buccal cavity. This state of affairs is not peculiar to this genus, but occurs in other Oligochaeta. O. multiporus shows one peculiarity, at present unique in the Oligochaeta; in a few of the posterior segments the nephridia are particularly abundant, and open, not only on to the exterior by numerous pores in each segment, but also into short diverticula of the hind gut. In this region of the body the nephridia are, exceptionally, provided with funnels. The vascular system of the Acanthodrilidae is constructed upon the same plan as is that of most other terrestrial Oligochaeta; unfortunately there is no published account of the vascular system derived from a study of the living worm, such as we possess of Megascoleaw and Pontoscolex ; the dorsal vessel is occasionally double, a condition which occurs in other Oligochaeta; the doubling of the dorsal vessel is chiefly met with in the New Zealand Acanthodrilidae, but not in all of them; it characterizes O. multiporus, O. huttoni, O. thomasi, and O. antarcticus; in these species the dorsal trunk is completely double from end to end of the body; in A. novae-zelandiae and in A. rosae the tube is double, except where it passes through the septa; at these points the two tubes become united. Above the oesophagus runs a supraintestinal trunk, which is connected with the posterior of the peri-cesophageal vessels; of these there are a number of pairs, and usually the last four of these are larger than the others, sometimes there are only three of these intestinal hearts; when there are four the last lies in the thirteenth segment; they are connected with the dorsal as well as with the supra-intestinal vessel; there is often, perhaps always, a pair of lateral vessels running along the body-wall in the anterior segments; according to Horst these vessels arise from the dorsal vessel, instead of arising as do their homologues in Perichaeta from the oesophageal plexus. DESCRIPTIONS OF GENERA AND SPECIES 521 The generative system of the Acanthodrilidae is very characteristic: the testes and the ovaries occupy the usual segments; as a rule they are upon the front walls of their segments as is nearly universal; but in A. annectens, as was pointed out by myself some years ago, the gonads are affixed to the posterior wall of their segments in close connexion with the ducts of the generative products, actually in contact with the funnels; Octochaetus is peculiar in that the ovaries alone have this abnormal position, the other gonads being normal in situation. A few species have only one pair of testes; this is the case with Kerria spegaz- zintt, and with A. pictus. In A. annectens, A. paludosus, and Diplocardia the sperm-ducts run within the thickness of the body-wall; probably this is so with other species, though the above mentioned species are the only ones in which this very unusual course of the sperm-ducts has been described. The two sperm-ducts of each side of the body remain separate until their opening on to the exterior; it used to be thought that each of them opened in connexion with one of the spermiducal glands; but it is now certain that in many species, and it is probable that in all, the sperm-ducts open separately from those glands on to the eighteenth segment. The spermi- ducal glands are long tubes’ which are in com- munication with the orifices upon the seventeenth and nineteenth segments already referred to. They consist of a proximal glandular and a distal muscular portion; the glandular part of the tube has in all the genera of the Acanthodrilidae, except Kerria, a lining of two layers of epithelial cells; its structure in fact is like that of the OCTOCHAETUS THOMASI. G. Gizzard. D.v, Dorsal vessel L.v, Lateral vessel. Sp.s. Sperm-sacs. H. Hearts. Ca. Calciferous glands. At. Spermiducal glands. clitellum; in Kerria, as in Pygmaeodrilus, Ocnerodrilus, and Gordiodrilus, the spermiducal gland is lined by only a single layer of cells; opening in common with the, spermiducal glands is a sac of penial setae in very many—the majority—of Acanthodrilidae; in a few species there are two kinds of setae, plain and ornamental, in a single bundle; these are absent in the genus Kerria. 3X 22 OLIGOCHAETA The spermathecae of the Acanthodrilidae are nearly always two pairs only; in Nplocardia communis, however, there are, exceptionally, three pairs; in all the rembers of the family, except Kerria, the spermathecae have a diverticulum or everal diverticula; it may happen that these appendices are so minute and so oncealed within the wall of the main pouch that they are invisible without iicroscopical examination; but such examination shows them to be invariably resent; these organs are invariably placed in the eighth and ninth segments. In few species, e.g. A. ungulatus and Benhamia beddardi, there are sacs of modified etae, very similar to the penial setae, in the neighbourhood of the spermathecae ; hey are often accompanied by glands. Affinities of Acanthodrilidae. This family of earthworms is not so easily separable from other families as it vas some years ago before the discovery of types like Neodrilus and ‘Acanthodrilus’ pegazzinii; BENHAM’s new genus Plagiochaeta, to which Bourne's ‘ Perichaeta’ tuartt may, perhaps, be referable, indicates a closer approach to the family Peri- haetidae even than Deinodrilus; with regard to this latter genus I pointed out its ntermediate characters between Perichaeta and Acanthodrilus in regard to the setae nd the clitellum; the setae are twelve in number to each segment, and the clitellum iccupies the three segments found in nearly all the members of the genus Perichaeta 3.8.) In Plagiochaeta there is an agreement with the Acanthodrilidae in the xistence of four spermiducal glands each provided with its bundle of penial setae, n the presence of calciferous glands, and in the form of the spermathecae; but the etae are very numerous in each segment, being arranged in a series of about twenty- ive pairs; the paired condition of numerous setae is unlike the condition of the etae in the Perichaetidae, where a grouping into pairs is not known unless in Megascolex sylvestris of Hurton, which may indeed be referable to the genus Plagiochueta. The disappearance, in Meodrilus, of the posterior pair of spermiducal glands night seem to indicate an approach to the family Cryptodrilidae; MicHAELSsEN (10) 1as compiled a very instructive table of the characters of two species of the Jryptodrilid genus Dichogaster and Benhamia rosea; practically the only difference retween the Acanthodrilid and the Cryptodrilid is the presence in the latter of two yairs of spermiducal glands; M1cHarLsEN, however, has perhaps not sufficiently mmphasized the fact that in the Acanthodrilidae the sperm-ducts never open on to he same segment as the glands; whereas in Dichogaster and in all Cryptodrilids DESCRIPTIONS OF GENERA AND SPECIES 523 (except Microscolew modestus) they do; but it might be replied to this that in Dichogaster damonis, there are three pairs of tubular glands having the structure of the spermiducal glands of these and other earthworms. Eliminate two of these three pairs and the condition found in the undoubtedly Acanthodrilid genus Neodrilus is arrived at. I think it must be admitted that the Acanthodrilidae have near relations to the Cryptodrilidae. At present, however, they differ by the situation of the spermiducal glands and the sperm-duct pores upon two or three consecutive segments. The genus Kerria seems to tend in the direction of the small group Ocnero- drilidae?; it has, as has the genus Ocnerodrilus and its near ally Gordiodrilus, spermiducal glands composed of only a single layer of epithelium; the spermathecae have no appendices, and there is a single pair of calciferous glands in the ninth segment. If the description by PERRrER of the position of the spermiducal glands on consecutive segments in A. obtusus be confirmed, there is another point of similarity between Acanthodrilus and Gordiodrilus. But this has, in my opinion, yet to be put beyond legitimate doubt. The genera of Acanthodrilidae. The family Acanthodrilidae can be divided up into several genera; there can be no doubt of the distinctness of Deinodrilus and Plagiochaeta, the characters of which are given below. Whether the absence of the second pair of spermiducal glands and spermathecae is sufficient to distinguish my genus Neodrilus is not by any means so certain; the original description of this worm has been confirmed (and added to) by Benyam; in A. schmardae one of the two pairs of glands, and similarly one of the two pairs of spermathecae, is decidedly smaller than the other; this leads, therefore, in the direction of Neodrilus; moreover, we have in the not far distant genus Gordiodrilus one species in which the spermiducal glands are reduced to a single pair; considering the close resemblance which Neodrilus bears in other characters to the genus Acanthodrilus, I am of opinion, that it should not be separated generically from such a form as A. dissimilis. In a recent paper Rosa has described a remarkable species of ‘Acanthodrilus,’ which he named ‘Acanthodrilus spegazzinii. This Acanthodrilid has only one pair of testes, and the spermathecae have no diverticula. In a worm which I have more ‘recently (25) described from the Pileomayo river the same characters are found; in addition to this the spermiducal glands are lined by a single layer of cells only; it 1 Including Ocnerodrilus, Nannodrilus, and Gordiodrilus. 3X2 524 OLIGOCHAETA is not stated by Rosa whether this is also the condition of the glands in ‘Acantho- drilus spegazzinii. Neither of the worms have penial setae. The position of the calciferous glands and the structure of the spermiducal glands, ally these two species to Ocnerodrilus as has already been pointed out; and I am disposed to form a separate genus Kerria for them, a genus which has been accepted by EIsen (4) who has added two new species to it. The remaining Acanthodrilidae comprise about sixty species; this is not perhaps an unwieldy number to include within a single genus; and until recently all these species, that is as many of them as were known—and no new structural characters have cropped up to render a change necessary on fresh grounds—were so included. Though all these species agree with each other in the characters made use of in the definition of the family given above, there is a much greater amount of structural variation among the different species than there is for example in the genus Perichaeta (s.s.), and a very great deal more than in Allolobophora and Lumbricus. This of itself seems to render the subdivision of the genus Acanthodrilus (sensu lato) desirable in order to secure a uniformity of treatment for the whole group. Never- theless, the task is not an easy one. It has been proposed at various times to form the following genera—Trigaster (BENHAM 8), Benhamia (MICHAELSEN 18), and Diplocardia (GARMAN 1); the name Acanthodrilus being applied to the remaining forms not included in these genera. The name Trigaster lankesteri was applied by BENHAM to an earthworm from the island of St. Thomas, differing from all the species of Acanthodrilus, at that time known, in the following points :—(1) the male pores enclosed by a ring surrounding a deep fossa; (2) clitellum reaching from segment xiii-xl; (3) spermathecae without diverticula; (4) three gizzards present. Two years later MICHAELSEN proposed to includ@ in a genus Benhamia those Acanthodrilidae ‘which have more than one gizzard, in which the segmental organs are arranged in many tufts on the walls of the segments, and an incomplete (that is, with a ventral gutter-like space) clitellum extends beyond the male generative openings.’ As this genus was considered to be merely an extension of Trigaster, the earlier name should, of course, have been retained, and was retained by Brnwam in his essay on the classification of the group (1), and by myself in a paper of similar scope (26). BENHAM, in the essay just referred to, defines the genus Trigaster (= Benhamia) as follows :— ‘Setae in four couples, all on the ventral surface; individual setae of each couple close together. ‘Clitellum occupies somites xiv-xl; complete ventrally only on the first few somites. ‘Spermiducal pores in xviii, and prostate pores in xvii and xix, in a large pit or fossa, occupying the middle of the ventral surface of somites xvii to xx, the margins of which are formed by two papillae. ‘Prostates as in Acanthodriius. No penial setae.’ A number of other characters follows, inclosed in brackets which indicates that they are less easy to observe or less distinctive—i.e. more subject to variation from species to species. But DESCRIPTIONS OF GENERA AND SPECIES 525 the definition, as it stands above, is really only applicable to the species Trigaster lankesteri; for Benhamia rosea nas penial setae, and a much less extensive clitellum. In a paper published subsequently to the one referred to above, MICHAELSEN alters his definition of the genus Benhamia so as to include some of the Acanthodrilidae previously described by Horst; the following species are the ones which are removed from Acanthodrilidae, and transferred to Benhamia:—B. schlegelii, B. buttikoferi, B. beddardi, and also Rosa’s species, B. scioana. The character of more than one gizzard present is thus dropped. Later still (13), Benuam again called attention to the generic subdivisions of the Acanthodrilidae, and proposed to retain both Trigaster and Benhamia, as well as, of course, Acanthodrilus itself. The three genera are defined by the use of the following characters :— 1. Acanthodrilus. Gizzard single; calciferous glands present. Anterior nephridia form a compact mass, opening into the alimentary tract. Spermathecae, two pairs in vii and viii. 2. Trigaster. Three gizzards; no calciferous glands. Clitellum, xiii-xl. Spermathecae in vili and ix, without appendices, and opening posteriorly ; no penial setae; no dorsal pores. 3. Benhamia. Clitellum, at most five segments; two gizzards; calciferous glands present; spermathecae in viii, ix, with appendices; penial setae present; dorsal pores present. These definitions may be, perhaps, admitted to distinguish Trigaster and Benhamia; but Acantho- drilus is not correctly defined; the spermathecae of that genus lie in viii and ix, and have diverticula ; the anterior nephridia do not always form ‘peptonephridia.’ Other characters, such as the paired nephridia, are omitted’. I shall now venture to give my own views with respect to the generic subdivisions of the family. Neither Bennam nor MICHAELSEN in distinguishing their genera Trigaster and Benhamia have taken into consideration my species Acanthodrilus multiporus®. This worm (see below) has diffuse nephridia, one gizzard, dorsal pores, and no ventral gutter surrounding the male openings. It doubtless comes nearest to Benhamia. This species differs from Trigaster and Benhamia in not possessing a marked median pair of folds surrounding the male pores, If we include all the species with multiple nephridia into one genus as was originally proposed to be done by MicuarnseEn, this difficulty will be got over; the name of this genus will evidently have to be Trigaster. I am disposed, however, to divide those Acanthodrilidae with multiple nephridia into three genera; this will permit of the use of more than one character as a generic definition, and is, moreover, in harmony with the geographical range of the species concerned. The genus Benhamia nearly restricted to the tropical parts* of the African continent will be defined thus :— : (1) Setae strictly paired, ventral pairs absent on segment xviii. 1 Bennam, however, is of opinion *that in Acanthodrilus a network exists in addition to the paired nephridia; this is not the case with the species I have examined. 2 See Micwartsen’s latest remarks (16), which I have not incorporated in the above. 3 Benhamia bolavi, found in Germany, is doutbless, as Micnarusen thinks, an importation. So perhaps are other extra-African species. 526 OLIGOCHAETA (2) Male reproductive apertures closely approximated and placed upon a well- marked depression surrounded by a ridge; penial setae. (3) Clitellum, xiii-xix (about). (4) Nephridia diffuse. (5) Two gizzards generally. The genus Trigaster restricted to the West Indies is thus to be defined :— (1) Setae strictly paired. (2) Male reproductive openings as in Benhamia, but no penial setae. (3) Clitellum, xiii-xl. (4) Nephridia diffuse. (5) Three gizzards. The New Zealand species, A. multiporus, A. hutiond, A. thomasi, and A. antarc- ticus, may be associated to form the genus Octochaetus which is thus definable :— (1) Setae in eight rows, one of two ventral setae of segments xvii, xix present. (2) Male reproductive openings as in Acanthodrilus; penial setae present or absent. (3) Clitellum, xiii—xix. (4) Nephridia diffuse. (5) Gizzard single. Garman’s (1) genus Diplocardia differs in a good many particulars from other Acanthodrilidae. The most remarkable external variation concerns the position of the spermiducal gland-pores and those of the, sperm-ducts. ‘These pores are really what they have been sometimes erroneously said to be in other Acanthodrilidae upon segments xviii-xx, instead of upon segments xvii-xix. This fact places the genus in rather an isolated position in the family, unless PeRRIER was correct in placing the apertures of the species described by himself in a correspondingly abnormal place. As this difference is enforced by others the genus must, I think, be allowed; the number and position of the spermathecae differs from that found in other Acanthodrilids; but these organs vary so much in other worms that it seems hardly reasonable to lay much stress on their variation in the case of Diplocardia ; there are, contrary to what is found in all other Acanthodrilids, three pairs which are in segments vi-ix. The structure of the spermiducal glands is perhaps, next to the position of the male pore, the chief reason for considering Diplocardia to be a distinct generic type of Acanthodrilid. The single species of the genus—Diplocardia communis—is in some other respects intermediate between Benhamia and Acantho- DESCRIPTIONS OF GENERA AND SPECIES 527 drilus as they are here defined; the chief resemblances to Benhamia lie in the absence of setae ventrally on the segment which bears the pores of the sperm-duct- pores, in the presence of two gizzards; in other respects the worm is like an Acanthodrilus. There remain then those species which have paired nephridia, thirty-six in all; it is not, however, in my opinion possible to sort these into generic or subgeneric groups. Even the genus itself, to which, of course, the name Acanthodrilus must be applied, has, as its only positive character, the presence of paired nephridia, and of a single gizzard. The following table shows the principal structural features of the several genera :— SETAE. curenium, | PENTA | wepurrpra, | DORSAL) DORSAL | giozarns,| SPERMIDUCAL |CALCIFEROUS| = yocarrry, SETAE. PORES. | VESSEL. GLANDS. GLANDS. Acanthodrilus paired or | xiii-xvi (xx) |+, rarely paired + oro] single or | one or tubular absent or in | New Zealand; distant; 8 oO double absent xiv-xviii Australia ; (some) Cape, Kerguelen ; S. America Benhamia . paired; 8. |xiji-xix(xxii)| +, rarely diffuse + oro single two tubular three in Africa; Java; absent on xviii ° QO xiv-xvi W. Indies Trigaster . .) paired; 8 xiii-xl ° diffuse ° single three tubular fo} W. Indies Diplocardia .| paired; 8 | xiii-xviii small paired. + double two tubular, with ° N. America absent on xviii indications of lobate structure Octochaetus distant ; 8 |xiii-xvii(xx)| small | diffuse + completely one tubular xiv-xvii New Zealand double (some) Deinodrilus .| distant; 12 xiv-xvi + diffuse ? sommletely one tubular ° New Zealand ouble Plagiochaeta .| paired; 54 xiv-xviii + paired ° single rudimen- tubular xiv New Zealand tary Kerria . . .| paired; 8 xifi-xix o paired ° single one tubular, lined ix 8. America with a single layer of cells Genus ACANTHODRILUS, PERRIER. Syn. Mandane, KINBERG. Lumbricus, GRUBE (in part.). Hegesipyle1, KINBERG. DEFINITION. Acanthodrilidae, with paired nephridia, the external pores of which either alternate in position from segment to segment, or, if fixed, are in front of one of the lateral couples of setae. Gizzard single. Calciferous glands present or absent. Clitellum, KII (XIII)-XVI (KIX); no genital fossa. Penial setae rarely absent. 1 Fide PERRIER, 528 OLIGOCHAETA This is by far the most extensive of the genera of Acanthodrilidae; it comprises eighteen well-marked species, besides a few others, of which we have not at present sufficient knowledge, and which, indeed, may not belong to Acanthodrilus (s. 8.) at all. To the latter category belong Hegesipyle hanno, of KINBERG, which PERRIER has determined (6) to be an Acanthodrilus; Mandane stagnalis, KINBERG, no doubt a true Acanthodrilus, since this is the only genus of the family which occurs in 8. America; Lumbricus kerguelarum, GRUBE, has been shown by MIcHAELSEN (10) to be referred to the Acanthodrilidae, and is perhaps synonymous with LANKESTER’S A. kerguelenensis. Finally, we have several species of ‘Lumbricus’ described by Hutton (1), which are, no doubt, as Hutton himself pointed out later (8), referable to the genus Acantho- drilus (sensu lato); probably most of these species are identical with those subsequently described by myself from New Zealand. The identity of Mandane with Acanthodrilus was suspected by PERRIER (3) and afterwards (6) proved; the name, however, cannot stand, as KINBERG used the same name in the same paper for a genus of Polychaeta'; neither can Hegesipyle; for, although PERRIER has shown it to be an Acanthodrilus, it is not clear whether it is referable to this genus in the strict sense. The species of the genus Acanthodrilus vary in size from an inch or so to twelve inches and upwards. It is one of the few genera which comprises aquatic as well as terrestrial forms. A. dalei and A. aquarum dulcium (see BrppaRD [48]) occur in streams in the Falkland Islands and ‘Mandane’ stagnalis was obtained from a pond near Montevideo. A. schmardae occurs in fresh water in Queensland. The prostomiwm shows differences which are usually, in other families of Oligochaeta, correlated with a sufficient number of other differential characters to be of generic value. In some species (e.g. A. novae-zelandiae) the prostomium is prolonged backwards so as to completely divide into two the buccal segment; in others it is not prolonged back so far or is merely a projection, separated from it of course by a groove from the buccal segment. The setae again show no such constancy of arrangement as is commonly met with in a single genus. In some species the individual setae of each couple are very close together; in others they are not. In A. capensis we have the intermediate condition ; the two setae of each couple are closely approximated anteriorly, wider apart posteriorly. In A. falelandicus the lateral setae are further apart than the ventral setae. Apart from the paired nephridia and the single gizzard there are no very salient differences between Acanthodrilus and Benhamia. I have noticed, however, that in Benhamia the calciferous glands are very distinct from the oesophagus ; they have the shape of reniform pouches, attached to the sides of the oesophagus. As a rule, 1 This extraordinary departure from the usual laws of nomenclature was first pointed out by Prrcrvan Wrieur. Zoological Record, vol, iii. p. 597, footnote. DESCRIPTIONS OF GENERA AND SPECIES 529 moreover (? always), there are three pairs of them in segments xiv, xv, and xvi. In Acanthodrilus, on the other hand, the calciferous glands present the appearance of swellings of the oesophagus; they are commonly fewer than three pairs, and they are often (as in A. georgianus and A. ungulatus) completely absent. In all the species of Acanthodrilus which I have myself examined with reference to this point, viz. A. novae-zelandiae, A. dissimilis, A. smithti, A. ungulatus, A. capensis, A. pictus, A. georgianus, A. falclandicus, and A. aguarwm-dulciwm, the ventral setae of segment xviii are present. In Benhamia crassa, B. stuhlmanni, and B. whytei these setae are absent; whether this is a charactcr of generic value remains to be seen. That the Acanthodrilidae with a diffuse nephridial system are near to those with paired nephridia is shown by the difficulty of getting characters other than this for distinguishing the genera. Furthermore there are special characters, confined to a very few species of Acanthodrilidae, which occur indifferently in members of more than one genus. The most striking example of a structure such as I refer to is the existence of the copulatory setae (as Horst terms them) and glands in the neigh- bourhood of the spermathecae in Benhamia beddardi, and in 4. ungulatus and A. schmardae. So also the double dorsal vessel—completely double—characterizes the earlier genus Octochaetus (three species) and Diplocardia communis. The ‘ pepto- nephridium,’ so characteristic of Octochaetus, is also met: with in A. annectens, A. paludosus, A. littoralis, and the genus Trigaster. The South American species form a more or less marked group; as compared with the New Zealand species indeed a well-marked group. They are all of small or moderate size. The clitellum is not extensive—xiii-xvi or xvii. Dorsal pores are usually wanting. The only species of Acanthodrilus with no more than a single pair of testes and vasa deferentia occur in this group. The dorsal vessel is invariably single. Calciferous glands are absent as specialized structures in all the species in which they have been carefully looked for, the vascular and much plicated walls of part of the oesophagus doing duty for them. If it were not for the Australian species I should be disposed to emphasize the above characters by separating off the Patagonian, Argentine, and Chilian Acanthodrilidae as a genus. The Australian species, however, are all of them so imperfectly known that it would be, in my opinion, unwise to attempt any such division of the genus Acanthodrilus. For A. macleayi has a clitellum comprising, as in the South American species, a small number of segments, while A. australis agrees with the New Zealand species in having a more extensive clitellum (xiii—xix). The New Zealand species of Acanthodrilus nearly all agree to differ from the species found elsewhere in that the nephridia are alternate in position. The only 3Y 530 OLIGOCHAETA exceptions are A. annectens and its near ally, A. paludosus—a species which recalls in some particulars the genus Octochaetus. It is indeed a question whether they should not be incorporated in that genus. The following are the points in which the two species in question resemble the . genus Octochaetus :-— (1) The great prominence of the papillae bearing the atrial pores. (2) The completely double dorsal vessel’. (3) The presence of an anterior peptonephridium. (4) The attachment of the gonads to the posterior wall of the segment. The arrangement of the setae is also somewhat similar, but as in species which are undoubtedly members of the genus Acanthodrilus (s.s.), such as A. georgianus, &e., the setae are disposed in the same fashion, the resemblance is obviously of less weight. In the two species above-mentioned the nephridia are paired, as in other Acanthodrilus; but the muscular end sac so universal in Acanthodrilus is here absent. There is thus a slight approximation to the diffuse nephridia of Octochaetus. A final indication of affinity between A. annectens and A. paludosus on the one hand and the genus Octochaetus is possibly afforded by the sperm-ducts which run in the thickness of the body-walls. But as this also occurs in A. comnvwwnis the resemblance is perhaps less noteworthy. The table printed on pp. 532 and 533 will serve for the discrimination of the species. I include the species of Octorhaetus and Diplocardia. Two out of the three species described by PERRIER appear to me to be hardly recognizable; this is hardly the fault of the describer, for he characterized them sufficiently to enable them to be separated from each other; there are not, however, enough points dealt with to fix their position with anything like certainty in the present state of our knowledge of the genus; it is certain, though, that they are all members of the family Acanthodrilidae. One of these species is, I believe, as was first pointed out by Horst, identical with that named provisionally A. layardi by myself (9). I now give some notes about the two remaining forms. (1) A. obtusus. This is a large worm, measuring about 700 mm. The male pores are said to be on the nineteenth and twenty-first segments. Penial setae ornamented with spinelets. Dorsal pores are present. Nephridia paired. A single gizzard in segments vii-ix. A pair of organs which seem to be most probably the sperm-sacs are present in the twelfth segment (the thirteenth is mentioned, but this seems most likely to be an error). It is suggested that they are the ovaries, but, although the segment which contains them bears out this suggestion, the sketch given is more like a pair of sperm-sacs. The spermathecae have no diverticula. The worm is from New Caledonia. The difficulty which prevents me from placing this species in the genus Acanthodrilus as here defined is, of course, the position of the male pores. Had it not been for the existence of the American Diplocardia, I should have been tempted, in spite of PERRIER’S accuracy in description, 1 Not, as in A. novae-zclandiae, single where it traverses the septa. DESCRIPTIONS OF GENERA AND SPECIES 531 to have assumed an error of two segments; but it will be noted that in the figure illustrating the anatomy of the species (3, Pl. ii, fig. 17) the organs in question are placed in exactly the same segments as they occupy in the description. The huge size of the species prevents me from identifying it with any known species of Acanthodrilus, and, on the whole, I think it safer to leave it in the category of a ‘species inquirenda.’ (2) A. verticillatus. This worm is placed by PERRIER in the genus Acanthodrilus, with a little doubt, as the sexual apparatus in the individual which he studied was reduced to the four sacs of penial setae. The length of the specimen was 350 mm. The setae are paired. The penial setae are upon the seventeenth and eighteenth segments. There is a gizzard. Attached to each sac of penial setae is a gland. I think that, from PERRIER’s description, there is no doubt that the worm is a member of the genus Kynotus, but, as this identification cannot be regarded as certain, I leave it, for the present, among the Acanthodrilidae ‘incertae sedis’ The above two species are the only two species named ‘Acanthodrilus’ about whose position in the system there is great doubt; I think that Rosa has correctly referred KInBERG’s Mandane stagnalis to his species A. spegazzinii, which will be considered later (see below). (1) Acanthodrilus dissimilis, Bepparp. A. dissimilis, Beppanrp, P. Z. S., 1885, p. 813. A. neglectus, BEDDARD, P. Roy. Soc., Ed. xiv, p. 156. Definition. Length, 143 mm.; breadth (at clitellum), 4-5 mm.; number of segments, 225. Clitetlum, XIV-XIX ; segments, XVII-XIX, with a ventral non-glandular area. Male pores connected by a straight longitudinal groove. Prostomium completely divides buccal segment, Setae paired. Dorsal pores visible in posterior region of body only. Gizzard in VI; calciferous glands in XV, XVI; in XIV oesophagus somewhat more globular than in preceding segments, but this dilatation is not comparable in size to the calciferous glands of XV, XVI. Intestine begins in XX. As the oesophagus gradually widens out to form intestine, it is difficult to state precisely where the latter begins. The third to the eighth septa after the gizzard are thickened. Hab.—New Zealand}. The remaining characters agree with those of A. parkerit. The spermathecae are of the same form, but I never observed more than two diverticula to each. The differences between this species and A. parkert are evidently but slight. The main difference is really one of size. The position of the gizzard, however, seems to distinguish the two species, as also the greater number of thickened septa in A. parkeri. On further consideration I reunite with the present species A. neglectus which I formerly separated. The differences between the two forms are limited, so far as I was able to ascertain, to a difference in the position of certain papillae in the anterior region of the body. At most, as it now appears to me, this difference is of value in establishing a variety. BENHAM has united the two species. 1 For notes on colour, locality, &., of this and other New Zealand species, see W. W. Smirx (2). 3X2 5382 OLIGOCHAETA SETAE. ‘CLITELLUM. | PROSTOMIUM. GIZZARD. NEPHRIDIA. Sea A, novae-zelandiae. . paired xiv-xix complete vi, viii paired none dis- alternate tinct A.annectens. . «. » 4 xili-xx incomplete v paired none A.paludosus . . . 93 5 v, vi 4 ” A. multiporus . . . distant i ' 9 diffuse xvii or xviii A.antarcticus . . . distant complete ” x A. dissimilis. . 1. paired xiv-xix 5 paired XV, Xvi A.parkeri . 1... fe xili-xix 53 vi, vii alternate xiv-xvi A.smithii . . . . $5 7 5 v, rudimentary i A.huttni 2. 2... distant xiii-xix (xx)] incomplete v diffuse Xv, Xvi A.thomasi . . . . ” xiii-xix ” v, vi ” xvii A. plumbeus. 2 . 3-4>1-2 xii-xix complete vi paired xiv, xv alternate A.picus. . 2... paired xiii-xvii | incomplete i paired none A. decipiens. . . . distant a complete » (2) ‘9 is A.hilgeri. . 2. . paired xiv-xvi ” present in viii-x 99 2 A. occidentalis . . . 5 ? ” vi a none A, australis. 2. 7p xiii-xix incomplete * ” ? A. magellanicus. . . distant xiii-xvii 3 ‘3 none A.ungulatus 2... paired xili-xvii complete vi, vii 55 A. platyurus. . . .| distant behind, ‘ $9 v, vi 55 absent paired in front Ht A.minutus. . . . paired xili-xvii 55 vi (?) ” a A. bicinctus. . a xiii-xvi | incomplete 7 7 © A.schmardage . .. 3 xiii-xviii ? present ” absent A.purpureus . . . 3 xiii-xvi | incomplete vii ” A.dalei. . . .. i ? complete vi, vii i 53 A. chilensis . . . .| paired in front xiii—xvi ss ‘ay ie A.capensis . 2. . distant incompfete present 43 A. kerguelarum. . . rc yy ” ” ” A.communis . . . paired xiii-xviii “9 two in vi and vii 5 ” A.cingulatus . . . a xiv-xviii complete vi, vii ‘9 9 A. littoralis . 2... distant xiii-xvii | incomplete present 3 33 A, putablensis . . .| distant behind, xiv-xvi complete vi rn 9 paired in front A.bovei . . . . .|distant,3-4>1-2| xiii-xvi incomplete rudimentary Pn ” A. georgianus . . . distant ” oe absent 9 ” A.carneus . . . . Fr $9 complete vi ” ” A. falclandicus . . . \distant, 3-4>1-2 9 incomplete |rudimentary in v 99 ” A. aquarum dulcium . es ” ” ” ” ” A.rosae. . . paired xiv-xix complete vi, vii ” xiv, XV A.macleayi. . . . * xii-xvi(xvii)} incomplete present 29g A. monocystis . . 45 xiii-xvii complete vi paired ? alternate A. valdiviensis . . . distant xiv-xvii | incomplete v, vi paired DESCRIPTIONS OF GENERA AND SPECIES 533 INTESTINE DORSAL LAST SPERM BEGINS. VESSEL. | HEARTS. SACS, xviii double xiii xi, xii ” ” xx 3 ix, xi, xii xix ” 3 xi, xii ” xx single 5 5 xviii ” ” ” ” ” ” ” 59 double xii xix ” xiii ” ” ” ” xvii single xii ix, x, xi g ” 2 ? 285 ix, x, xi xvii 4 xiii xi, xii x, xi, xii ” xii xi, xii xix 5 xiii x, xi, xii ” ” ix, X1 xvii 5 xi ? ” ” ” Zs xii Pr es ix (? x), xi ” ” x1 xvi or xvii ” xiii [ix,x, xi, xii X, xi, xii xvii double xii ” single ” 2 ” ” x1 ” xiii ix, xiii s xi, xii Y xii ix, xi xvi ss xiii xi, xii $5 xii double xiii ? single? ? xv double xvii single xii ix, xi PENIAL SETAE. OTHER STRUCTURES. not ornamented absent present ” not ornamented ” ” absent 2 ornamented not ornamented ” absent not ornamented " ornamented ” ” not ornamented ornamented not ornamented ornamented present ornamented ” ” ” not ornamented ornamented ” not ornamented ornamented ” peptonephridium ; gonads on posterior walls of segments; sperm-ducts im- bedded in body-wall peptonephridium ; anal nephridia on posterior wall of xiii; gonads a single pair only of gonads in x; no dorsal pores copulatory setae in neighbourhood of spermathecae a single pair of testes in x testes in x only ” ” copulatory setae and glands sperm-duct imbedded in body-wall ; three pairs of spermathecae testes in x only no dorsal pores; only a single pair of testes and vasa-deferentia (in x); pepto- nephridium present (?) genital papillae in ix, x, xi genital papillae on x; no dorsal pores ‘testes in x only genital papillae on x; no dorsal pores genital papillae on xviii, xx ; no dorsal pores only one pair of spermathecae and spermi- ducal glands 534 OLIGOCHAETA (2) Acanthodrilus parkeri (NEW sPECIEs). Definition. Length, 184 mm.; breadth (at clitellum), 9 mm.; number of segments, 185. Clitellum, XIII-XIX (2). Male pores on very slightly prominent papillae, corresponding to ventral pairs of setac, those of each side connected by a straight longitudinal groove. Prostomium complete. Setae paired. Dorsal pores visible in posterior region of body only, Gizzard rather elongated in VI, VII; caleiferous glands in XIV, XV, XVI; the two last pairs much the largest. Intestine begins in XVIII, typhlosole inconspicuous, Len septa following the gizzard are thickened, particularly the second and the next sia. Nephridia paired and alternate. Dorsal vessel single; four pairs of hearts are in A-XIIT, Sperm-sacs in XI, XI, flattened and oval. Penial setae stout and curved like an f; extremity thick and blunt without any ornamentation. Spermathecae, each with two well-marked diverticula of a mulberry-like appearance; occasionally three diverticula present. Hab—New Zealand. (3) Acanthodrilus novae-zelandiae, BEppARD. A. novae-zelandiae, BEpparp, P. Z.S., 1885, p. 813. Definition. Length, 280 mm.; breadth (at clitellum), 10 mm.; number of segments, 240 (about). Clitellum, XIV-XIX; a median area lies between ventral setae from segment AVI onwards. Male pores corresponding to ventral pairs of setae, those of each side connected by a straight longitudinal furrow, which passes exactly between two setae of segment XVII. Prostomium complete. Setae paired. Dorsal pores in posterior region of body. Body square in outline posteriorly with sloping sides; setae implanted at the angles. Gizzard in VI, VII; calciferous glantls hardly developed, but walls of oesophagus in XIII-XVI thick and vascular, Intestine begins in XVIII, typhlosole slight. First septum in front of gizzard separating V/VI; this and following segment which embraces the gizzard at about the middle, thin and membranous. The ten following septa thickened, particularly those separating segments IX/XVI. Nephridia paired and alternate. Dorsal vessel double, the two tubes uniting temporarily when they traverse the septa ; hearts in X-XTIH. Sperm-sacs in XI, XIL. Spermathecae with a single mulberry-like diverticulum, often lying in front of the septum, behind which lies the pouch. Penial setae not ornamented. Hab.—New Zealand. (4) Acanthodrilus rosae, Bepparp. A, Rosae, Bepparp, Q. J. M.S., vol. xxx, 1890, p. 434. Definition. Length, 250 mm.; breadth, 10 mm.; number of segments, 236. Colour dark DESCRIPTIONS OF GENERA AND SPECIES 535 brown (im alcohol) verging towards purple on the dorsal surface. Clitellum, XIV-XIX, not developed ventrally upon XVII-XIX. Male pores upon inconspicuous papillae; the two pores of each side connected by a longitudinal groove. Prostomium completely divides buccal segment. Dorsal pores not seen. Setae paired. Gizzard im VI, VII; calciferous glands in XIV, XV. Intestine begins in XVIII. Septa X/XV_ slightly thickened. Dorsal vessel as in A. novae-zelandiae; so too hearts. Nephridia paired and alternate. In neighbourhood of pharynx are well-developed blood-glands. Sperma- thecae with diverticulum terminating in a mulberry-shaped extremity. Hab.—New Zealand. This species might be confused with A. novae-zelandiae, but for two points of difference: (1) the absence of any greatly thickened septa; (2) the stalked character of the spermathecae diverticulum. (5) Acanthodrilus monocystis (BEepDpDsRp). Neodrilus monocystis, BEDDARD, P. Roy. Soc. Ed., vol. xiv, p. 157. Definition. Length, 70 mm.; diameter, 5-6 mm.; number of segments, 155. Setae strictly paired. Prostomium completely divides buccal segment. Clitellum, XIII-XVII, saddle- shaped. Gizzard in VI; intestine begins in XV, and has no typhlosole. No specially thickened septa. Last heart in segment XIV. Nephridia alternate. Sperm-sacs in X—XII. One pair of spermiducal glands opening on to XVII, and continued back by a groove on to the following segment ; penial setae beset by minute asperities distally. Spermathecae, one pair in VIII, with a very large diverticulum lying in “segment in front. Hab— New Zealand. I have come to the conclusion that it is not permissible to retain the genus Neodrilus for this species, in spite of its possessing only one pair of spermiducal glands. The species has been investigated, not only by myself, but, in some respects more fully, by BenHAmM (19). The latter paper contains a good series of illustrations. The species evidently comes nearest to A. dissimilis, but it is more slender in appearance, and quite unmistakable, even before dissection. (6) Acanthodrilus smithii, Beppanp. A. smithii, BEDDARD, P. Z. 8., 1892, p. 675. Definition. Length, 75 mm.; diameter, 3 mm.; number of segments, 114. Colour (of preserved specimens), violet above. Prostomium completely divides buccal segment. Setae strictly paired, dividing body into equal areas. Clitellum, XIII-XIX, saddle-shaped. 536 OLIGOCHAETA Dorsal pores absent (?). Gizzard, rudimentary, lying in V; in XIV, XV oesophagus dilated to form rudimentary caleiferous glands ; intestine commences in XVIII. Nephridia alternate in position. Dorsal vessel single; last heart in XIII. Sperm-sacs in IX—XII. Spermathecae with three diverticula, of which one is constantly in front of the septum, behind which lies the pouch. Penial setae bifurcate at tip, with two delicate wing-like processes, smooth. Hab.—New Zealand. This species contrasts strikingly with the remaining New Zealand species by its strong pigmentation. (7) Acanthodrilus litoralis (K1vBERG@). Mandane litoralis, Kinperc, Ofv. Svensk. Akad., 1866, No. 4, p. 100. ? Mandane patagonica’, Kinpenra, loc. cit., p. 100. Definition. Length, 100 mm.; diameter, 6 mm.; number of segments, 120. Prostomium, prolonged over half of buccal segment. Clitellum, XIII-XVII; complete sacs for a non-glandular area on last two segments. Setae im four double series, but individual setae some way apart. Nephridiopores in front of third seta, commencing in segment VII (at latest). Male pores corresponding in position to ventral setae. Sperm-duct pores on XVIIT, between setae 1 and 2. No dorsal pores. Spermathecal pores in front of third seta. Gizzard present ; intestine begins in XVII. Sperm-sacs only one pair, in XI, to which correspond a single pair only of sperm-duct funnels in X. Last hearts in XII. Spermathecae two pairs in VIII, IX ; diverticulum single, with a branched lumen. Peniat setae ornamented with variously sized spines. Hab.—Straits of Magellan; near the shore. A. peculiarity of this species, according to Rosa (6), is the possession of certain glands which he terms ‘ghiandole filatrici.’ They occur in the anterior segments, on the anterior face of the septa, but no apertures were discovered. They are compared to the tufts of nephridia which occur in a similar situation in Trigaster lankesteri, and to the ‘Spinndriisen’ of the Capitellidae*. They may perhaps be also compared to the specially dense mass of nephridia which occur in the Perichaetidae in a few of the anterior segments. More likely, perhaps, they are ‘peptonephridia,’ like those of A. annectens, &c. 1 The query is that of Rosa. * H. Erste, Die Capitelliden, Fauna u. Flora des Golfes v. Neapel, xvi, p. 324. The resemblance in the secretion (bundles of filaments) of the glands in the Acanthodrilus and in the Capitellidae is very remarkable. DESCRIPTIONS OF GENERA AND SPECIES 537 (8) Acanthodrilus hilgeri (Micnaztsey). Mandane Hilgeri, MIcHAELSEN, SB. Hamb. wiss. Anst., vi, 1889, p. 8. Definition. Length, 95 mm.; diameter, 3 mm.; number of segments, 93. Colour, in alcohol, grey violet above. Prostomium completely divides buccal segment. Clitellum, XIV-—XVI, complete, Setae strictly paired. Nephridiopores in front of dorsal setae. Male pores corresponding to ventral pair of setae. Gizeard in segments VIII, IX, X. Spermathecal pores in front of ventral pair of setae. No penial setae, the ordinary setae being present. Sperm-sacs in IX-XI. Spermathecae, with a single diverticulum longer than the pouch. Hab.— Corral, Chili. : (9) Acanthodrilus pictus (MicHAzLsey). Mandane picta, MICHAELSEN, loc. cit., p. 5. Definition. Length, 132 mm.; breadth (at clitellum), 8 mm.; number of segments, 135. Segments not marked by annuli. Colour (in alcohol), brown ; after clitellum a broad purplish brown band, limited by dorsal setae, appears on dorsal surface. Clitellum, XIII —(XIV)-XVII, undeveloped ventrally. Male pores on slightly prominent papillae, in @ line with outer seta of ventral couple; Sperm-duct pores slightly dorsal of these. Prostomium continued by grooves about half-way over buccal segment, after a groove which divides buccal segment into two halves. Setae in couples, upon prominent papillae ; those of ventral couple nearer to each other than dorsal, especially behind clitellum. Dorsal pores absent. Gizzard in VI; in XV oesophagus becomes wider, and has a much-folded lining membrane ; this is the equivalent of cabciferous glands. Intestine begins in XVII, First . septum lies in front of gizeard, i.e. V/VI. Anterior septa not much thickened ; those between XI/XII, XII/XIII most. Dorsal vessel single ; hearts wm X, XI, XII. Nephridia paired, opening in front of dorsal setae; the muscular terminal sac of nephridium has a short caecum. A single pair only of sperm-duct funnels in X; the sperm-sacs are in IX, XI, racemose in character. Spermiducal glands not very long; penial setae flattened, and widened out just before pointed free eutremity, not ornamented. Sperma- thecae with large diverticulum. Hab—Rio Bruno, 8. Chili; Corral, Valdivia, MICHAELSEN places the sperm-sacs in segments x, xi; I think, however, that the ‘sperm-sac’ of segment x is a sperm-reservoir. The above description is mainly taken from my own notes. 32 538 OLIGOCHAETA (10) Acanthodrilus valdiviensis (NEW SPECIES). Definition. Length, 65mm.; diameter, 5mm.; number of segments, 99. No integumental pigment visible in alcohol specimen. Prostomium extends over about. half of buccal segment. Clitellum extends over XIV-XVII, complete except on XVII. Setae not strictly paired, dorsal a little further apart than ventral. Groove connecting mate pores passes to outside of ventral setae of segment XVIII. Oviducal pores in front of and to inside of ventralmost setae. Last pair of hearts in segment XII, The gizzard is in segments V, VI; intestine commences in the middle of segment XVII. The septa dividing segments VII/XVII are thickened. The nephridia have a distinct caecum. One pair of rosettes and testes in X; sperm-sacs in IX, XI; sperm-reservoirs in X. Spermathécae with very large diverticulum. Penial setae with pointed hooked extremity, just behind which they are somewhat swollen; behind this again the setae are marked with denticulate ridges. Hab.—Corral, Valdivia (Mr. A. Lane). (11) Acanthodrilus dalei, Bepparp. A. Dalei, BEDDARD, Q. J. M.8., vol. xxx, 1890, p. 433. Definition. Length, 40 mm.; diameter, 4 mm.; number of segments, 77. Prostomium completely divides the buccal segment. Clitellum XITI-XVIT. —Setae strictly paired. Nephridiopores in front of dorsal pair of setae. Sperm-sacs in IX, XI, Gizzard in segments VI and VII, the intersegmental septum being present. Penial setae with a few denticulations near to free end, which is edpanded. Spermathecae with a single large diverticulum as big as pouch, Hab—Fatkland Islands ; in fresh water. The violet-red colour of this species and its complete prostomium sufficiently distinguish it from its allies. (12) Acanthodrilus platyurus, MicHarisen?. A. platyurus, MIcHAELSEN, Arch. f. Nat., 1892, p 226. Definition. Length, 180 mm.; breadth, 7 mm.; number of segments, 150. Prostomium complete, Clitellum, XIII-XVII, saddle-shaped. Colour during life, ‘flesh-coloured, clitellum clear brown? Male-pores upon circular papillae connected by grooves in the 1 As Micwsetsen’s single specimen was ‘sehr stark erweicht,’ and, therefore, necessarily very difficult to interpret, I have not hesitated to expand his description in accordance with my results obtained from the study of other specimens. DESCRIPTIONS OF GENERA AND SPECIES 539 way common among the Acanthodrilidae, opening in line of ventral setae. Setae anteriorly in four pairs, the ventral setae on the first segments being a little further apart than the lateral ; towards the genital orifices these setae become more approximated. In the posterior region of the body the setae of each couple are a little more separated. Dorsal pores visible behind clitellum. Gizzard in V, VI; calciferous glands absent. One pair of papillae on XX on a line with ventral setae. A pair of funnels in X. Sperm-sacs in IX, XI, racemose. Penial setae much curved at extremity and ornamented with numerous forwardly directed spinelets. Spermathecae apparently without diverticula, but these are possibly represented by the thick circular swelling at the base of each, opening an line with ventral setae. Hab.—Estancilla, Valdivia, Chili. (13) Acanthodrilus capensis, Bepparp. A. capensis, BEDDARD, P. R. Phys. Soc., 1885-6, p. 369. Definition. Length, about 80 mm. Setae: in the anterior region of bedy ventral setae form a closely approximated couple, while the two lateral setae are much further apart ; posteriorly (after the male generative pores) the ventral setae get further apart, but are not so widely separated from each other as the lateral setae. Gizzard present ; intestine begins in XVI or XVII. Male pores corresponding to interval between two ventral setae, which latter are wanting. Sperm-duct pore to outside of ventral setae. Oviducal pores in front of tower setae of ventral couples. Last heart in XII. Spermathecae with a single small diverticulum opening to outside of outermost setae of ventral couple. Sperm-sacs in segments IX-XII. Penial setae beset with numerous forwardly directed spinelets. Hab.—Cape Colony. This species is very active in its movements like Perichaeta. My original descrip- tion of it is clearly inaccurate in some particulars, as I pointed out later (9). The above probably requires revision in the location of some of the organs. In some specimens examined there were a number of genital papillae; in one as many as six pairs on segments vii-—xii. (14) Acanthodrilus kerguelarum (Gruzz). Lumbricus kerguelarum, GRUBE, MB. k. Akad. Wiss., Berlin, 1877, p. 552. A. kerguelarum, MicuartsEn, Arch. f. Nat., 1891, p. 226. A. kerguelenensis, LANKESTER, Phil. Trans., vol. 168 (extra vol.), p. 264. Lumbricus (Dendrobaena) kerguelarum, VAILLANT, Annelés, p. 167. 322% 540 OLIGOCHAETA Definition. Length, 38-47 mm.; number of segments, 92. Prostomium round, imbedded in, but not continued by grooves on to buccal segment. Setae in eight rows, those of ventral pair approach each other more closely in segments XVI-XIX. Clitellum, XIII-XVI, complete. Spermathecae each with two diverticula. Sperm-sacs three pairs in X—XII, the last pair racemose, the others not so. Penial setae with numerous small spines— the apices directed forwards—on free extremity. Hab.—Kerguelen, Marion Island. That Lumbricus kerguelarum of GRuBE was in all probability an Acanthodrilus was first pointed out by myself (41, p. 301, footnote). VAILLANT, nevertheless, ranged it (6, p. 167) in the genus Lwmbricus, though certainly putting the species among ‘Lumbrici dubii. Gnrusz’s description is given in full, and it is curious that VAILLANT did not suspect that the ‘papillae’ of the seventeenth and nineteenth segments, were, as I suggested, the male pores; VAILLANT did, however, go so far as to suggest that the worm might belong to the intraclitellian group of PERRIER. The justice of my own suggestion was confirmed later by MICHAELSEN who ex- amined the types. MICHAELSEN considered that the species was not identical with LangeEster’s A. kerguelenensis; this opinion was chiefly based upon ditierences in the shape of the penial setae, which seem to me to be too slight for recognition. I have examined a single specimen evidently referable to the same species, which was collected during the voyage of H.M.S. ‘Challenger’ on Marion Island. I have, therefore, been able to fill up a few lacunae in the previous descriptions, which are incorporated in the above definition. This species comes, perhaps, nearest to A. capensis, but is to be distinguished from it by the arrangement of the setae. (15) Acanthodrilus georfianus, MicHsEtsen. A. Georgianus, MIcHAELSEN, JB. Hamb. wiss. Anst., v, 1888, p. 68. Definition. Length, 60 mm.; diameter, 5°5 mm.; number of segments, 87. Prostomium prolonged over two-thirds of buccal segment. Clitellum, XIU-XVI, incomplete on last two segments. Setae four pairs, but the individual setae are at some distance from each other ; posteriorly the setae are separated by equal intervals; anteriorly there is a tendency to a paired arrangement. No dorsal pores. Nephridiopores in front of cnterval between setae 2 and 3, but nearer to latter. No gizzard ; typhlosole completely absent. Sperm-sacs in XI, XII. Spermathecae two pairs in VIII, IX; each with two diverticula, Penial setae with a few blunt tubercles on free extremity. Hab.—South Georgia. The sperm-sacs are said by MIcHAELSEN to arise as a number of separate spherical DESCRIPTIONS OF GENERA AND SPECIES 541 or pear-shaped saccules which ultimately fuse to form a single racemose sperm-sac on each side of gut in segments xi, xii. The spermiducal gland has a remarkably fine lumen. There is apparently a tendency for the glandular cells of its walls to be gathered into separate masses (see p. 118). (16) Acanthodrilus falclandicus, Bepparp. A. georgianus, Bepparp, Q. J. M. S., vol. xxx, 1890, p. 421. A. falclandicus, BEDDARD, P. Z.8., 1892, p. 678. Definition. Length about 75 mm. Setae in eight rows, distance separating lateral setae greater than that separating ventral. Prostomium extending on to buccal segment for about one half the diameter. Ctitellum, XIII-XVI, complete. No dorsal pores. Gizzard rudimentary in V; intestine begins in XVI and has a rudimentary typhlosole. Last heart in XIII. Sperm-sacs in XI, XII; median sperm-reservotr in IX-XV. Penial setae of two kinds, some smooth, some ornamented ; the later with a number of serrated tubercles at free end. Hab—Falkland Islands. I originally confounded this species with MicHAELSEN’s A. georgianus. MICHAELSEN, however, in a paper published subsequently to the one in which he first described the species, pointed out the main differences, most of which are indicated in the descriptions of the two species given above. In addition to these I may mention that in A. falclandicus the nephridiopores are directly in front of the third setae. In my definition of A. georgianus I have not referred to the existence of smooth as well as ornamented penial setae; these are, however, figured by MicHAELSEN (15, Pl. ii, fig. 4c), but he has expressed the opinion that the smooth setae are so because they are immature. I do not think this myself or I should emphasize this as a further difference between the species. A. georgianus seems to want the median sperm-reservoir of the present species, as well as the septal sacs (‘glycogenic organs’). MIcHAELSEN has suggested that A. falclandicus is synonymous with Rosa’s A. bovei. There is, I have pointed out (57, p. 679), no doubt that they are near to each other; but not, I think, identical. As, however, Rosa’s description is, on account of the poorness of his specimens, in some respects defective, it is not easy to be quite certain. In the meantime A. bovei is a much smaller species; the tubercles on the penial setae are not stated to be denticulate as they are in A. falclandicus; the clitellum of A. bovei has, as is the case with A. georgianus, a median non-glandular area on segments xv, xvi. In A. falclandicus, however, the same space may be occasionally seen, so that this character is not likely to 542 OLIGOCHAETA distinguish the species. The apparent differences in the genital papillae are of less weight, as there is much variation in these structures. (17) Acanthodrilus aquarum-dulcium, BepDpDARD. A. aquarum-dulcium, Brepparp, P. Z.8., 1892, p. 680. A. georgianus, BEDDARD, Q. J. M.S., vol. xxx, 1890, p. 421 (in part.). Definition. Length, 47 mm.; diameter, 3 mm.; number of segments, go, No specially thickened septa, Penial setae with a series of minute denticles at free end. In other respects like A. falelandicus. Hab.—Fatkland Islands ; in fresh water. I originally confounded this species with A. falclandicus, or, as I then called it, (erroneously) ‘georgianus. Later its differences from that species were pointed out; there can be, I think, no doubt of its distinctness. The chief difference is in the form of the penial setae. The worm also is of a much more slender build than A, falclandicus, which has possibly something to do with its aquatic habit. I have not used the papillae as differential characters as these structures are so apt to vary that they must be used with the greatest caution, and, indeed, I have endeavoured never to rely entirely upon them. In specimens of this species examined as transparent objects in glycerine, there were to be seen two pairs of papillae lying between the ventral setae on each of segments xviii, xx—a pair to each that is to say. This species may also differ—but this is perhaps very doubtful—from the last in the fact that it has egg-sacs which I did not observe in A. falclandicus. ¢ (18) Acanthodrilus bovei (Rosa). Mandane Bovei, Rosa, Ann. Mus. Civ. Genova, vol. vii (2a), 1887, p. 143. Definition. Length, 35 mm.; diameter, 3 mm.; number of segments, 100. Prostomium prolonged over two-thirds of buccal segment. Clitellum, XIII-XVI, rendered incomplete on last two segments by a triangular area of non-glandular epidermis. Setae in eight series, distance between which increases dorsally. Male pores correspond im position to second setae. Spermathecal pores are related to the same setae. Papillae, two pairs on X, XI, between ventral setae; a median papilla on IX, Penial setae ornamented with ‘large obtuse tubercles. Spermathecae in VII, IX, each with two diverticula), Hab.— Puntarenas, Straits of Magellan. 1 ‘Nefridiopori e port dorsali non visti’ (Rosa). DESCRIPTIONS OF GENERA AND SPECIES 543 (19) Acanthodrilus macleayi, Fietcuer. A. Macleayi, Furrcuer, Proc. Linn. Soc. N. S. W., iv (2), 1890, p. 999. Definition. Length, 27 mm.; diameter, 2 mm.; number of segments, 90. Prostominm prolonged over less than half the buccal segment. Clitellum, XII-XVI (XVII). Setae strictly paired. Papillae large, median swellings on XVI, XVII, and a few following segments. Male pores ventral of the position of the first setae. Penial setae flattened at free extremity, ‘minutely notched distally. Hab.— Napier Range, N. W. Australia. FLETCHER is not quite clear as to the sperm-sacs, which, according to him, lie in x, xii. The alimentary canal has a gizzard. This is the smallest species of Acanthodrilus. (20) Acanthodrilus australis, Micuarnsnn. A. australis, MIcHAELSEN, JB. Hamb. wiss. Anst., vi, 1889, p. 9. Definition. Length, 140 mm.; diameter, 6 mm.; number of segments, 443. Prostomium does not divide buccal segment. Clitellum, XIIIJ-XIX. Setae strictly paired. Dorsal pores appear to commence XII/XIII. Papillae in pairs on intersegmental furrows, X1/XII, XII/XII, XVIII/XIX, between ventral and lateral pairs of setae. Gizzard in segment VI. Nephridiopores in front of dorsal setae. Male and spermathecal pores in line with ventral pair of setae. Sperm-sacs in X, XI, XII. Spermathecae with minute diverticula concealed in the walls of the duct. Penial setae particularly long, 2°4 mm., not ornamented, Hab.—Cape York, Austraha. (21) Acanthodrilus schmardae, Bepparp. A. Schmardae, BepparD, Ann. and Mag. Nat. Hist., Feb., 1892, p. 132. Definition. Length, 60 mm.; diameter, 5mm, Clitellum, XIT-XVII, incomplete. Dorsal pores present. After gizzard are five thickened septa. Anterior pair of spermiducal glands are much larger than those which follow. Penial setae with ornamentation. Spermathecae with an inconspicuous diverticulum ; posterior pair the larger. Copulatory glands and setae in the neighbourhood of the spermathecae ; one pair of these glands behind last pair of spermathecae and a sac of copulatory setae between them; a second pair behind these. Setae not ornamented. Hab.—Rockhampton, Queensland ( fresh water). 544 OLIGOCHAETA (22) Acanthodrilus annectens, Brpparp. A. annectens, BEDDARD, Q. J. M. S., vol. xxix, 1889, p. 102. Definition. Length, about 75 mm. Colour during life ‘pink, or white and pink, Prostomium not completely dividing buccal segment. Clitelium, XITI-XIX, saddle-shaped. Male pores in position of seta 2, which is absent, seta 1 being present. Sperm-duct- pores to the outside of ventral pair of setae. Gizzard in V; no caleiferous glands, Intestine with well-developed typhlosole. Dorsal vessel double; last hearts im XIII. Nephridia open by outermost setae; the first pair is a ‘ peptonephridium. Gonads attached to hinder wall of their segments. Sperm-ducts imbedded in body-wall. Spermathecae cach with four diverticula, opening on to exterior in front of and to ventral side of third seta. No penial setae. Hab.—New Zealand. This species and the next form a very distinct pair of Acanthodrilus, as will be seen from a comparison - of their characters with those of other species. I have not referred in the above definition to the genital papillae which are present in this as in so many other species of the genus. In one specimen there were a pair lying in line with the ventral pair of setae between segments ix/x; behind these there was a single median papilla on xv and another on xvi; in segments xix, xx were three papillae, two on one side of the middle line and one on the other. Another specimen had a papilla on each of segments xviii, xix. (23) Acanthodrilus paludosus, Bepparp. A. paludosus, Bepparp, P. Z. 8., 1892, p. 677. Definition. Length, about 25 mm.; diameter, 1 mm. Clitellum, XITI-XIX. Setae distant ; the outer setae only of ventral pair on XVII and XIX missing. Male pores correspond in position to missing seta of their segment. Sperm-duct pores to outside of ventral setae of XVIII. Papillae on XI, XII, and XVIII. Gizzard in V and VI chiefly in , the latter segment ; intestine begins in XX. First pair of nephridia modified to form a peptonephridium. Sperm-ducts run in the thickness of the body-wall, uniting just at external pore. Sperm-sacs in IX, XI, and XII. Spermathecae each with two small diverticula. Penial setae absent. Hab.—New Zealand (in a marsh). This species comes nearest to A. annectens; it differs from it principally in the DESCRIPTIONS OF GENERA AND SPECIES 545 fact that the gonads are normal in position, i.e. attached to the front wall of their segments. I found no egg-sacs, but as the clitellum was not developed, the single specimen examined by sections was not fully mature. (24) Acanthodrilus ungulatus, Perrier. A. ungulatus, Perrier, Nouv. Arch. Mus., 1872, p. 85. A. Layardi, BepparD, P. Z.8., 1886, p. 168. Definition. Length, 1-2 ft. Prostomium completely dividing the buccal lobe. Clitellum, XII-XVII, complete eacept on last segment. Setae strictly paired, absent only on segments XVII, XIX ventrally where they are replaced by the penial setae. Dorsal pores commence between segments X/XI. Sperm-duct pore lies to outside of ventral pair of setae. Dorsal vessel single; last hearts in XII. A gizzard present. Sperm-sacs in X, XI, XIL. Spermathecae with a very indistinctly marked diverticulum. Copulatory glands and setae near to them. Penial setae ornamented with jagged cross ridges. Hab.—New Caledonia. I have no doubt that Horst (2) is correct in identifying my A. layardi with PerRIER’s A. wngulatus. The most marked peculiarity of the species is the presence of copulatory setae and glands in the neighbourhood of the spermathecae. In, my description of the species I referred to the presence of a pair of pores upon the buccal segment on either side of the prostomium; this requires identification by means of sections; and therefore, until better preserved material is examined it is necessary to lay stress upon this supposed character of the species, which is at any rate unique among earthworms. The accessory copulatory structures found in the vicinity of the spermathecae are by no means always developed even in sexually mature individuals. I found them in various stages of development; and Horst did not find them at all in the specimens which he examined. The position of the ovary of this species (perfectly normal) which I failed to find was discovered by Horst. (25) Acanthodrilus decipiens (NEW sPECtES). Definition. Length, 35 mm.; diameter, 2-3 mm.; number of segments, 110. Clitellum, XUTI-XVILI. Median genital papillae upon XVII, XIX, XX. Prostomium complete. Setae paired, but not strictly. Dorsal pores present. Gizzard large. Nephridia paired. Spermathecae with one diverticulum of good size. Spermiducat glands extend through three segments. Penial setae unornamented. Hab.—Estancilla, Valdivia. 4A 546 OLIGOCHAETA (26) Acanthodrilus occidentalis (NEW SPECIES). Definition. Length, 192 mm.; diameter, g mm.; number of segments, 365. Prostomium complete. Sctae strictly paired, on ventral surface of body. Dorsal pores commence at segment XI or XIL, Giezard in VI; no calciferous glands; intestine begins in XVII. Last hearts in XIII. Nephridia paired. Testes in X, XI; sperm-sacs in XI, XH. Spermathecae with long tubular caecum. Spermiducal glands occupy one segment only ; penial setae unornamented. Hab.—Valparaiso. This species has an appearance very like that of Octochaetus multiporus. During life it had a colour described by MricHAELSEN as ‘blue-grey; head-end rose.’ (27) Acanthodrilus magellanicus (NEW sPECIES). Definition. Length, 66 mm. ; diameter, 3°5 mm.; number of segments, about 100. Clitellum, XTHI-XVIT; genital papitiae, a pair on XI, median elongate papillae upon XIV, XV. Setae not strictly paired, ventral nearer than lateral. Gizzeard in VIL Septa VI/XII, stout. Last heart in XII. Nephridia paired. Testes in X, XI; sperm-sacs in XI, XI; spermathecae with two caeca, one above the other ; spermiducat glands, confined to their segment, open separately from penial setae, which are ornamented with transverse ridges. Hab.— Magellan’ s Straits. This species might be mistaken on a first inspection for A. bovei; it has the same absence of integumental pigment. (28) Acanthodrilus minutus (NEW SPECIES). Definition. Length, 29 mm.; diameter, 3 mm.; number of segments, 70. Clitellum, XITI- XVII. Prostomium complete. Setae strictly paired. Gizzard large; intestine begins im XVII. Testes in X; sperm-sacs in XI; spermathecae with tubular diverticulum ; spermulucal glands confined to their own segment, the anterior pair larger. Penial setae not ornamented, Hab.—Putabla, Valdivia, 8. America. This species again is one of those that appear to have no integumental pigment, which gives to it a superficial resemblance to A. bovei. (29) Acanthodrilus bicinctus (NEW srEct=s). Definition. Length, 42 mm. ; diameter, 3mm.; number of segments, 80. Chitellum, XIII-XVI; median genital papillae on XX, XXI, XXII, XXIII. Prostomium incomplete. Setae DESCRIPTIONS OF GENERA AND SPECIES 547 sirictly paired. Gizeard well developed. Testes in X; sperm-sacs in XI; spermathecae with a long diverticulum, Spermiducal glands occupying segments XVI-XX. Penial setae armed with spines, Hab.—Picton Island ; Juan Island, 8. America. This species, closely allied to A. dalei, has the same plan of colouration as has that species. (30) Acanthodrilus purpureus (NEW sPECIEs). Definition. Length, 95 mm.; diameter, 5 mm.; number of segments, 98. Clitellum, XII-XVI, complete. Prostomium does not extend over buecal segment. Setae strictly paired. Gizeard in VII. Last heart in XII. Spermathecae with tubular diverticulum dilated at end. Spermiducal glands extend through several segments. Penial setae with spinelets. Hab.—Magellan’s Straits. This species is of the frequent dark-violet colour. (31) Acanthodrilus chilensis (NEW sPEctrs). Definition. Length, 80 mm.; diameter, 5 mm.; number of segments, 150. Clitellum, XILI-XVIL, —Prostomium complete. Setae strictly paired anteriorly, wider apart posteriorly, but the divergence is not so marked as in A. platyurus. Gizzard in VI, VII. Septa VII/XII, stout. Last heart in XII. Testes in X ; sperm-sacs in XI. Spermathecae with short diverticulum. Spermiducal glands not long. Penial setae of a brown colour in form like those of A. platyurus. Hab.—Teja Island, Valdivia. The colour (in alcohol) is dark purplish. (32) Acanthodrilus cingulatus (NEW sPEctzs). Definition. Length, 58 mm.; diameter, 4 mm.; number of segments, 106. Clitellum, XIV-XVIUI. Prostomium complete. Setae strictly paired. Gizzard in VI, VIL. Testes in X; spermathecae with small diverticulum. Spermiducal glands much coiled, anterior pair larger, Penial setae as in A. platyurus. Hab.—Teja Island, Valdivia. The colour in alcohol is rather brown than violet. (33) Acanthodrilus putablensis (NEW SPECIES). Definition. Length, 82 mm.; diameter, 8 mm.; number of segments, 150. Clitellum, XIV-XVI. Prostomium complete. Setae strictly paired anteriorly, divergent posteriorly, and more so than in A. platyurus. Gizeard in VI. Septa VILI/XIV, stout, Last hearts in XIII, Testes in X; sperm-sacs in IX, XIII. Spermathecae with two short 4A2 548 OLIGOCHAETA diverticula. Spermiducal glands confined to their segment, posterior pair smallest. Penial setae like those of A. platyurus. Hab.—Putabla, Valdivia. (34) Acanthodrilus carneus (NEW SPECIES). Definition. Length, 52 mm.; diameter, 3°5 mm.; number of segments about 100. Clitellum, AILI-XVI, complete. Prostomium complete. Setae paired but not very strictly, ventral closer together. Genital papillae paired on IX, unpaired on X, XI. Dorsal pores begin in front of clitellum. Gizeard in VI. Last heart in XII. Testes in X; sperm-sacs in IX, XT; spermathecae with wavy tubular long diverticulum. Spermiducal gland with slender unornamented penial setae. Hab.—Quilipue, 8. America. (35) Acanthodrilus plumbeus (NEW SPECIES). Definition. Length, 28 mm. ; diameter, 2mm. ; number of segments, 54. Colour (im alcohol) a dull leaden blue. Prostomium complete (2). Setae closely paired ventrally, distant dorsally, Clitellum, XII-XTX, undeveloped between ventral setae. Dorsal vessel single up to segment XIV, in and after which it is double, the tubes uniting at septa; last heart in XIII. Nephridia alternate. Gizzard not strongly marked in VI. Calciferous glands in XIV, XV. Sperm-sacs in XI, XII. Spermathecae consisting of an oval sac sharply marked off from duct, which has thick muscular walls and is of about the same length and diameter. The latter bears a short globular sessile appendix which alone contains sperm. Spermiducal glands short, limited to their segments. Penial setae ornamented by transverse ridges, abruptly truncated at end, but, seen laterally, end in a point. Hab—Mount Pirongea, Auckland, New Zealand. I owe this species to the kindness of Capf. Broun of Drury, N.Z, Genus DIPLOCARDIA, GARMAN. Syn. ? Geodrilus, UpE. DEFINITION. Setae paired, absent from segment XIX on which lie male pores; spermiducal gland pores on XVIII, XX; clitellum, XIII-XVIII. Gizzards two in V, VI. Nephridia paired. Dorsal vessel double. Spermiducal glands tubular in appearance, but with glandular cells into lobules opening often by separate ducts; penial setae small; spermathecae three pairs in VII-IX. The genus at present is only known by one species, unless indeed ‘Geodrilus singularis’ of UDE be a different species. In any case it appears to me that the genus Geodrilus should not be separated from Diplocardia. It (Geodrilus) has, DESCRIPTIONS OF GENERA AND SPECIES 549 according to Ub, two gizzards, paired nephridia and three pairs of spermathecae ; but the male pores are stated to occupy the normal position for Acanthodrilidae, and nothing is said about the dorsal vessel. Diplocardia communis, Garman. D. communis, GARMAN, Bull. Illinois Lab., vol. iii, 1888, p. 47. ? Geodrilus singularis, Upn, Z. wiss. Zool., 1893, p. 69. Definition. Length, 300 mm.; number of segments, 165. Colour while living i-ii>ii-ili >iii-iv;’ anteriorly, ‘i-ii< oe eee BEDDARD, 18). (6) Allolobophora mammalis (Savieny). Enterion mammale, Savicny, Mém. Ac. Roy. Inst. Fr. (Analyse), v, 1826, p. 181. Lumbricus mammalis, Duais, Ann. Sci. Nat., (2) viii, 1837, p. 22. A. celtica, Rosa, Boll. Mus. Zool. Torino, 1886, No. 2. L. (Allolobophora) mammailis, VaILLant, Annelés, p. 148. A. (Dendrobaena) celtica, FrrzenD, J. Linn. Soc., 1892, p. 297. Definition. Length, 40 mm.; breadth, 24 mm. ; number of segments, 100. Clitellum, XXXI- XXXVI, First dorsal pore. Tubercula pubertatis on XXXIIT, XXXIV. Setae in eight rows, the intervals increasing from below upward. Hab.— Brittany ; England ; Scotland. This species shows that remarkable alternation in the position of the nephridio- pores which is characteristic of other species of the genus, and which has already been dealt with. (7) Allolobophora foetida (Saviany). Enterion foetidum, Saviany, Mém. Ac. Roy. Inst. Fr. (Analyse), v, 1826, p. 182. Lumbricus annularis, TEMPLETON, Mag. Nat. Hist., vol. ix, 1836, p. 234. DESCRIPTIONS OF GENERA AND SPECIES 703 L. foetidus, Ducis, Ann. Sci. Nat., (2) viii, 1837, p. a1. L. olidus, HorrMEIsTER, De Verm. Quib., 1842, p. 24. L. brevispinus, GERSTFELDT, Mém. Sav. Etrang. Ac. St. Pétersb., viii, 1859, p. 269. Allolobophora foetida, Eisen. Ofv. Svensk. Akad, 1873, No. 8, p. 50. L. (Allolobophora) foetida, VAILLANT, Annelés, p. 147. Definition. Length, 90 mm.; breadth, 4 mm.; number of segments, 105. Clitelium, XXV, XXVII-XXXII. Setae strictly paired. First dorsal pore, IV/V. Tubereula pubertatis, XXVITI-XXXI. Spermathecae, two pairs in IX, X, opening posteriorly, very dorsal in position, Hab.—Europe ; America; Asia, Sc. (universally distributed). This species has a very characteristic coloration; the ground colour is a flesh tint marked in each segment by a ring of purplish. (8) Allolobophora chlorotica (Savieny). Enterion chloroticum, Saviany, Deser. Egypte, t. xxii. E. virescens, SAVIGNY, ibid. Lumbricus anatomicus, Duaks, Ann. Sci. Nat., xv, 1828, p. 292. L. chloroticus, Ducts, Ann. Sci. Nat., (2) viii, 1837, p. 19. L. riparius, Horrmetster, Arch. f. Nat., 1843, p. 189. L. viridis, JoHNsTON, Cat. Worms, 1865, p. 60. Allolobophora riparia, EIsEN, Ofv. Svensk. Akad., 1873, No. 8, p. 46. A. neglecta, Rosa, Att. Acc. Torino, 1882, p. 170. A. chlorotica, VEJDOVSEY, Syst. u. Morph., 1884, p. 60. Aporrectodea chlorotica, OERLEY, Ert. termesz. Kor., 1885, p. 22. A. (A.) chlorotica, Rosa, Boll. Mus. Zool. Torino, 1890, No. 160. Definition. Length, 100mm. ; number of segments, 100. Clitellum, XXIX, XXX-XXXVIL. First dorsal pore, IV/V. Setae paired, but not so close as in A. turgida. Tubercula pubertatis on XXXI, XXXII, XXX. Spermathecae, three pairs in IX—XI, opening on to VIII/IX, IX/X, X/XI, in line with lateral setae. Hab.—Europe ; Azores ; Palestine. This species is to be also recognized by its green colour, which does not appear to be so bright as in A. smaragdina. Coloured figures are to be found in the works of Ersen, HorrmMeister, and D’UDEK=EM. Ersen’s figures include his two varieties, ‘pallescens’ (=var. A. anatomica, Rosa) and ‘rufescens. Rosa has ‘recorded a yellow or flesh-coloured variety from Treviso. The worm, when annoyed, gives out a yellow or green fluid, from dorsal pores, which is inodorous. I imagine that the above synonymy is more likely to be accurate than that of other species, 704 OLIGOCHAETA owing to the generally marked colour of the worm, and its habit, alluded to by HorrMEisTER and D’UpEKEM, of bending into a circle when touched. Anatomically, it differs by the presence of three spermathecae. In A. neglecta (later regarded by Rosa as merely a variety) there are four or five pairs of tubercula on xxxi-xxxv. (9) Allolobophora complanata (Ducts). Lumbricus complanatus, Duais, Ann. Sci. Nat., xv, 1828, p. 292. A. complanata, Rosa, Lumbr. Piemont., 1884, p. 40. L. (Dendrobaena) complanatus, VAILLANT, Annelés, p. 117. A. (Octolasion) complanata, Rosa, Boll. Mus, Zool. Torino, 1893, No. 160, p. 9. Definition. Length, 180 mm.; diameter, 10 mm.; number of segments, 190. Clitellum, XXVITI-XXXVIT. Setae distant, the intervals diminishing from below upwards. First dorsal pore, XI/XIII. Tubercula pubertatis in the form of two lines on clitellar segments. Spermathecae, seven pairs in VI-XII, Hab.—Mediterranean district (including Palestine and Algeria). The above definition has been taken from Rosa’s description of the species, excepting only as regards the first dorsal pore, which Rosa found to be between segments xiii/xiv, a little behind the position assigned to it by Upr. The anatomy of this worm has been investigated by Ducks, Rosa (19), Ube (8), and by myself (13). The spermathecae lie often partly in one segment and partly in the following or the preceding segment, as was first pointed out by myself; this character, however, is mentioned neither by, Ducts nor Rosa; MIcHAELSEN has found a similar state of affairs in A. studiosa. The sperm-sacs, are remarkably inter- mediate in character between those of the typical Allolobophora on the one hand, and those of a Lwmbricus on the other. (10) Allolobophora norvegica, E1sxn. A. norvegica, Eisen, Ofv. Svensk. Akad., 1873, No. 8, p. 48. Lumbricus norvegicus, LEvinsEN, Vid. Med., 1883, p. 243. L. (Allolobophora) norvegicus, VAILLANT, Annelés, p. 143. Definition. Length, about 100 mm.; number of segments, 120. Setae strictly paired. Chitellum, XXVI-XXXI. Tubereula pubertatis on XXVIII, XXIX, XXX, XXXII, Hab.— Norway. DESCRIPTIONS OF GENERA AND SPECIES 705 This is another uncertain species, coming so near to A. nordenskidldii that, if they had not been both described by the same writer, I should have been disposed to put them down as identical. .(11) Allolobophora tumida, Essen. A. tumida, Ersen, Ofv. Svensk. Akad, 1874, No. 2, p. 45. Definition. Length, about 30mm.; number of segments, 50. Colour reddish brown. Setae paired at four angles of quadrangular body. Clitellum, XXIJ-XXIX. Tubercula pubertatis, XXVIII, XXVIII. Hab.—New England ; Denmark (?)}. There is no doubt that Rosa’s suggestion as to the possibility of this worm being an Allurus is reasonable. (12) Allolobophora parva, EIssn. A. parva, Eisen, Ofv. Svensk. Akad., 1874, No. 2, p. 46. Lumbricus parvus, TAUBER, Ann. Dan., 1879, p. 68. Definition. Length, about 100 mm.; number of segments, about 100. Setae paired closely, but dorsal more so than ventral. Clitellum, XXIV-XXX. Tubercula pubertatis, XXV-XXX. Hab—New England, Denmark?. (13) Allolobophora eiseni (LEvINsEn). Lumbricus Eiseni, LEvinsen, Vid. Med., 1883, p. 241. A. (Dendrobaena) Eiseni, Frrenp, J. Linn. Soc., 1892, p.302. A. Eiseni, Rosa, Mem. R. Acc. Torino, 1893, p. 66. Definition. Length, 40 mm.; diameter, 4 mm.; number of segments, 110. Colour iridescent violet above, red-brown on clitellum. Setae strictly paired. Clitellum, XXIV, XXV-XXXIL. Tubercula pubertatis, none. First dorsal pore, V/VI. Spermathecae absent. Sperm-sacs in XI, XII. Hab.—Europe generally. (14) Allolobophora boeckii (Ersey). Lumbricus puter, Eisen, Ofv. Svensk. Akad., 1870, No. To, p. 959. Dendrobaena Boeckii, E1s£n, ibid., 1873, No. 8, p. 53. D. puter, Orrtey, MT. Akad. Math., xvi, 1880, p. 586. 1 Fide TauseR; but Levinsen distrusts the latter’s identification. 2 Levinsen doubts Tauser’s identification. 4X 706 OLIGOCHAETA Lumbricus Boeckii, TauBER, Ann. Dan., 1879, p. 69. D. Camerani, Rosa, Att. Acc. Torino, 1882, p. 172. Dendrobaena rubida, VEJDOVSKY, Syst. u. Morph., 1884, p. 60. A. Boeckii, Rosa, Lumbr. Piemont., 1884, p. 48. Octolasion Boeckii, OERLEY, Ert. temesz. Kor., xv, 1885, p. 20. A. (Dendrobaena) Boeckii, Frrenp, J. Linn. Soe., 1892, p. 298. Definition. Length, 35 mm.; number of segments, 95. Clitellum, XXIX-XXXII, XXXIV Setae distant. Tubercula pubertatis on XXXI-XXXII[. Hab.—Europe. It might appear from the above synonymy that the name of the species should be ‘puter ;’ but Eisen himself pointed out that his Lwmbricus puter was not the same species as HorrmeEisTer’s Lumbricus puter: both Vespovsky and Ku.aain (8, p. 94) regard Lumbricus rubidus of Ducts (1) as a synonym of the present species. VEJDOVSKY remarks upon this question (24, p. 60), ‘Unbegreiflicher Weise legt Horr- MEISTER Ent. rubidwm als Synonym zu seinem Lumbricus olidus, was ich nur aus dem Umstande erklire, dass er, wie er erwahnt, nur die in Weingeist konser- virten Savigny’schen giirtellosen Typen vergleichen konnte. Allein die schon von Duats gegebene Beschreibung von seinem Lumbricus rubidus zeugt, dass diese Art mit Lwmbricus puter, Horr. identisch ist. Ducks sagt namlich, pag. 24: “Du reste il y a aussi de bandelettes (tubercula pubertatis, E1szn) sous le trentiéme, trent et uniéme, et trent deuxiéme anneaux... Ce qui le distingue surtout, ce sont les rangées de soies trés écartées les unes des autres, quoique réellement géminées.”’ VEJDOVSKY, however, has overlooked another point in the description of the species, and that is the position of the spermathecae, which open close to the dorsal median line. This character is evidence of the species being really Lumbricus olidus of HorrMeister (=A. foetida), or perhaps A. veneta of Rosa, which was not, as a matter of fact, described at the time when VEspovsKy wrote. Rosa certainly says nothing about the spermathecae of Allolobophora boeckit ; neither does Erszn ; but Rosa places it in his fourth group of Allolobophora, which is characterized by the fact that these organs open in line with the third seta. VzEJpovsKy finds but one pair, concerning the exact position of the orifice of which he says nothing. The setae too of Allolo- bophora boeckit, although they resemble those of HorrmzISTER’s species in being in four rows, are really different in their arrangement; and are, according to Rosa, sufficient in themselves to identify the species. The lateral spaces are nearly equal, but decrease slightly from below upwards. These spaces are so large that the dorsal space is only twice the width of the superior lateral space; the ventral space is smaller than the dorsal and is only a little wider than the inferior lateral space. DESCRIPTIONS OF GENERA AND SPECIES 707 (15) Allolobophora subrubicunda, Eisen. A. subrubicunda, Eisen, Ofv. Svensk. Akad., 1873, No. 8, p. 51. A. arborea, EIsEn, ibid., p. 47. A. tenuis, HIsEN, ibid., 1874, No. 2, p. 44. Lumbricus subrubicundus, Levinsrn, Vid. Med., 1883, p. 242. Octolasion subrubicundum, OERLEY, Ert. termesz. Kor., Xv, 1885, p. 20. A. putris Hoffm. forma subrubicunda Eisen, Micuazisun, JB. Hamb. wiss. Anst., viii, 1891, p. 18. . (Allolobophora) subrubicundus, VAILLANT, Annelés, p. 143. . (Allolobophora) tenuis, VAILLANT, Annelés, p- 144. - putris, Micuarismn, Arch. Ver. Nat. Meckl., 1890, p. 49 (?in part.). . subrubicunda, formae typica et arborea, MicHAELSEN, JB. Hamb. wiss. Anst., vii, 1890, p. 15. L L L. (Allolobophora) arboreus, VAILLANT, Annelés, p- 149. A A A. (Dendrobaena) subrubicunda, FrienpD, J. Linn. Soc., 1892, p. 29. A. (Dendrobaena) arborea, FRIEND, ibid., p. 301. ? = L. puter, HorrMEIsTER et ALII. ? =A. Fraissei, OERLEY, Zool. Anz., 1881, p. 285. Definition. Length, 75 mm.; breadth, o4 mm.; number of segments, 110. Clitellum, AXVI-XXXI. First dorsal pore V/VI. Setae paired, but not closely. Tubercula pubertatis on XXVIII-XXX. Spermathecae, one pair in X, opening in line with lateral setae. Hab.—Hurope; Azores ; N. America ; Patagonia. This is another species with a complex synonymy. EIsen united his two species, A. tenuis and A. arborea, which were formerly held to be distinct, after the examination of a larger number of specimens; in the same paper he further said: ‘Some of the specimens (of A. tenuis) . . . also show a swelling on the , twenty-seventh (twenty-eighth) segment, which might be mistaken for a tuberculum pubertatis, and which also indicates the relation to the preceding species, A. subru- bicwnda, but with which it never occurs. Levinsen has placed all three together under the name ‘subrubicwndus, a position which MIcHAELSEN has also taken up. MIcHAELSEN, however, distinguishes the three supposed species as three ‘forms’ of one species; he has added to these the species ‘constricta’ of Rosa, and a new form ‘hortensis’; the former is described in the present work as a distinct species, and a ' 708 OLIGOCHAETA the latter has been shown by Rosa to be a variety of his A. veneta. It will be noticed, therefore, under the description of that species. The fact that this species has only a single pair of spermathecae, is a point of resemblance to A. boeckii, with which, indeed, it may have been partly identified by VEJDOVSKY, since he places among the synonyms of his Dendrobaena rubida both A. boeckit and Lumbricus puter of HorrMEIsTER, which Rosa and others regard as probably a synonym of the present species. These two species differ markedly in the position of the clitellum and the tubercula pubertatis. I have not included in the list of synonyms of this species Enterion rubidum of Savieny, Rosa (15, p. 76); though regarding it as ‘species inquirenda,’ and as not corresponding perfectly to A. putris, thinks that it is probably the same. (16) Allolobophora icterica, Rosa. A. icterica, Rosa, Att. R. Ist. Venet., 1886, p. 685. ?=Enterion ictericum, Saviany, Mém. Ac. Roy. Inst. Fr. (Analyse), v, 1826, p. 183. Definition. Length, 80 mm.; breadth, 5 mm.; number of segments, 190. Clitelliim, XXXIV-— XLIV. Setae strictly paired. Tubercula pubertatis forming a ridge along clitellar segments. Spermathecae in X, XI, opening anteriorly in line with outer setae. Hab.— Ltaly. Rosa, who has described the species, identifies it with. inconsiderable doubt with Saviany’s Enterion ictericwm. This identification depends chiefly upon the similar position and extent of the clitellum, which is only paralleled in A. gigas and A. dubiosa. None of the two later species can be confounded with £. actericum, as they have not paired setae. The principal difference between Saviany’s L. ictericwm and the species called A. icterica by Rosa, is that the former has four pairs of spermathecae. Rosa, however, states that in his species one individual had the two pairs of spermathecae doubled. Something of the same kind may possibly account for the ‘four’ pairs of spermathecae in SAVIGNY’s species. (17) Allolobophora hispanica, Ups. A. hispanica, UbE, Z. wiss. Zool., 1886, p. 135. Definition. Number of segments, 220. Clitellum, XXIX-XLIII. Setae paired. First dorsal pore, XII/XIIT. Tubercula pubertatis on ali the clitellar segments (?). Hab.—Spain. DESCRIPTIONS OF GENERA AND SPECIES 709 The colour of this species (which has the size of Lwmbricus herculeus) is a dirty brown dorsally, greyer in front, and paler behind ; the clitellum is yellowish. The setae behind the clitellum appear to be larger than those in front. UpE has said nothing about the spermathecae. (18) Allolobophora molleri, Rosa. A. molleri, Rosa, Boll. Mus. Zool. Torino, 1889, No. 63. Definition. Length, 150 mm.; breadth, 4mm.; number of segments, 210. Dorsal pores commence IV/V. Tubercula pubertatis on L-LVII. Setae strictly paired. Spermathecae im VIII, IX, opening between VII/VII, VILI/IX, in line with dorsal setae. Hab.— Portugal. This species comes nearest to A. trapezoides and A. chlorotica, but is very distinct from both, not only in the position of the spermathecae, but also in other points. The colour of the living worm is very characteristic : the ground colour is rose, which passes dorsally into a greenish, but in the posterior region of the body the entire worm is of an intense green, which has even a tinge of blue. The clitellum was not developed, but doubtless lies in the neighbourhood of the segments occupied by the tubercula pubertatis. There are papilla-like convexities on xii-xiv, and sometimes also xx, which bear the ventral setae. The male pores (on the fifteenth segment) are connected with longitudinal ridges, which reach back to the tubercula. (19) Allolobophora tellinii, Rosa. A. Tellinii, D. Rosa, Boll. Mus. Zool. Torino, 1888, No. 44. Definition. Length, 500 mm.; breadth,15 mm.; number of segments, 264. Clitellum, XXV, XXVI, XXVII-XLI. First dorsal pore, V-VI. Sctae paired, those of dorsal pairs more strictly paired. Tubercula pubertatis on XXXII-XXXVII. Spermathecae in X, XI, opening between IX/XI, XI/XII. Hab.—Italy. This species is one of the largest of the genus; it was found at an altitude of 220 m.; its colour is whitish, with a brownish-purple band on each segment. The setae (ventral) of segments viii-xii borne upon glandular papillae. There appear to be only two pairs of sperm-sacs in Xi, xil. (20) Allolobophora transpadana, Rosa. A. transpadana, Rosa, Lumbr. Piemont., 1884, p. 45. Octolasion transpadanum, OERLEY, Ert. termesz. Kor., xv, 1885, p. 19. 710 OLIGOCHAETA Lumbricus terrestris, var. stagnalis, OERLEY, Mt. Akad. Math., 1880, p. 583. ? = Enterion opimum, Savieny, Mém. Ac. Roy. Inst. Fr. (Analyse), v, 1826, p. 183. [Unnamed worm], Horst, Notes Leyd. Mus., 1887, p. 297. Definition. Length, 90 mm.; diameter, 5 mm.; number of segments, 155. Clitellum, XXIX, XXX, XXXVIT. Setae, as in A. complanata.~ Dorsal pores commence X1/XII. Tubercula pubertatis, forming two lines on all of clitellar segments. Spermathecae, five pairs in VI-VII, X, XI. Hab—lItaly. This species has been chiefly studied by Rosa. BoreELit has shown that the nephridia alternate in the same way that they do in other species. The spermathecae have a curious arrangement; the first three open by the posterior septum of their segments; the fourth opens by the septum ix/x; the fifth by the septum x/xi. The colour is earthy brown, like A. complanatu, perhaps more yeilowish in the middle of the body. Rosa has described a variety from the neighbourhood of Venice, which is distinguished by its colour and smaller size ; the colour is greyish, with a bluish tinge, rose anteriorly, and reddish at the posterior end; this coloration is stated by Rosa to be identical with that of A. profuga. Enterion opimum of SAviany is stated to have only four pairs of spermathecae. (21) Allolobophora alpina, Rosa. A. alpina, Rosa, Lumbr. Piemont., 1884, p. 28. A. (Notogama) alpina, Rosa, Boll. Mus. Torino, 1890, No. 160, p. 3. Definition. Length, 50mm.; number of segments, £30. Clitellum, XXVII, XXVITI-XXXII, AXATV. Setae distant. Tubercula pubertatis on XXX-XXXII. Spermathecae in IX, X, opening on to IX/X, X/XI, near to dorsal line. Hab.—Italy ; Palestine. This species is like A. foetida, A. veneta, and perhaps also A. rubida, in the position of the spermathecal pores. (22) Allolobophora festae, Rosa. A. festae, Rosa, Boll. Mus. Zool. Torino, 1892, No. 122. Definition. Length, 35 mm.; breadth, 2 mm.; number of segments, 180. Clitellum, XX, XXI-XXXIIT. — Tubercula pubertatis on XXIX-XXXI. Setae strictly paired. Sperma- thecae, two pairs in XII, XIII (2), opening by dorsal setae. Hab.—Tunis. DESCRIPTIONS OF GENERA AND SPECIES 711 This species is characterized by the above definition; the account given by Rosa deals with but few points, besides those mentioned in the definition; it is not quite clear from his description whether the spermathecae are in segments xii and xiii or in xili and xiv; he merely says that the external opening is on the line between segments xii and xiii and xiii and xiv; the shape of these organs appears to be characteristic; they are described as being ‘claviformi, molto allungati.’ There are special accessory papillae upon segments xvi and xxvi, which bear the ventral setae ; the last pair are not so constant as the first, and are connected by a raised transverse ridge. (23) Allolobophora smaragdina, Rosa. A. smaragdina, Rosa, Boll. Mus. Zool. Torino, 1872, No. 130. Definition. Length, 80 mm.; breadth, 6 mm.; number of segments, 104. Clitellum, XXIV, XXV-XXXII. First dorsal pore, IV/V. Tubercula pubertatis on XXX-XXXII. Setae paired, ventral in position. Spermathecae, two pairs in IX/X, opening IX/X, X/XI, in line with dorsal setac. Hab.—Bleiberg, Carinthia ; at 1coom. The most noticeable character of this species, when alive, was the bright green colour, which, as Rosa observes, is a rare colour among earthworms. The colour seems to be like that of A. molleri, Microchaeta rappit, and a Benhamia referred to above (p.559). The sperm-sacs are four pairs in ix-xii, without any median sperm-reservoir. (24) Allolobophora constricta, Rosa. A. constricta, Rosa, Lumbr. Piemont., 1884, p. 38. A. subrubicunda forma constricta, MICHAELSEN, JB. Hamb. wiss. Anst., vii, 1890, p. 15. Definition. Length (in alcohol), 20 mm., when alive up to 45 mm.; number of segments, 100. Clitellum, XXVI-XXXI. Setae paired but not strictly. No tubercula pubertativ. No spermathecae. Hab.—Italy. The reasons which led MIcHAELSEN to regard this species as at most a variety of A. subrubicwnda were the variability in the tubercula pubertatis coupled, of course, with the other points of agreement, such as small size and position of the clitellum. Out of twenty-two specimens of A. swhrubicunda collected, fourteen belonged to. the variety ‘constricta’; the rest were intermediate in characters. The first lot had no trace of tubercula, and were partly mature and partly immature to some extent ; 712 OLIGOCHAETA the fully ripe ones had spermatophores attached to the body. The other eight showed traces of tubercula on segments xxix, xxx. Unfortunately MIcHAELSEN made no mention of the presence or absence of spermathecae, which would have decided the question ; until accurate information is forthcoming that the spermathecae are missing frequently in the typical A. swhrubicwnda, I think it necessary to retain Rosa’s species A. constricta. (25) Allolobophora profuga, Rosa. Lumbricus terrestris, var. lacteus, OERLEY, Mt. Akad. Math., xvi, 1880, p. 584. A. profuga, Rosa, Lumbr. Piemont., 1884, p. 47. Octolasion profugum, OERLEY, Ert. termesz. Kor., xv, 1885, p. 17. O. lacteum, OERLEY, ibid., p. 21. A. cyanea, Rosa, Mem. R. Acc. Torino, 1893, p. 59 (in part.). ?=Lumbricus stagnalis, HorrMeIsTER, Die bisj. bek. Art. Regenw. 1845, p. 35. Definition. Length, about 60 mm.; diameter, 3 mm.; number of segments, 165. Clitellum, XXX-XXXV. Setae as in A. complanata. Tudercula pubertatis, XXXI-XXXIV. Spermathecae, two pairs in X, XI, opening in line with third setae, between IX/X, X/XI. First dorsal pore, X/XI or XI/XI. Hab.—Italy ; Germany ; Spain ; Argentine. This species has been described by Rosa and by UDE; the descriptions of these two writers differ in some small points ; in others the observations of UDE supplement those of Rosa. In the definition of the species I have followed Rosa, only adding to the facts given by him the position of the first dorsal pore, not mentioned by Rosa, but referred to by Upr. Ubs’s specimens were rather larger, measuring up to 150 segments. The clitellum is a little more extensive, extending over segments XXIX, XXx-xxxv!; the tubercula pubertatis form a groove which reaches from the middle of segment xxx to the middle of segment xxxv. The position of the first dorsal pore varies from x/xi to xi/sii. On the authority of Upz I add (as he did doubtfully) Lumbricus stagnalis of HorFMEISTER as a synonym. I do not, however, see any grounds for this identification; ‘Luwmbricus stagnalis’ does seem to belong to this section of Allolobophora, but it might also be A. veneta—indeed the extent of the clitellum is more suggestive of this species. Rosa mentions that this species has the same odour of garlic that characterizes A. complanata and A. transpadana ; from the anterior segments it emits a colourless fluid, and, after the fifteenth, a yellow fluid. This species is said by Rosa to have bilobed spermathecae. } Rosa (15, p. 60) thinks that Upz had both this species and A. studiosa (which Rosa unites) in his hands at the time that he wrote the description. DESCRIPTIONS OF GENERA AND SPECIES 713 (26) Allolobophora veneta, Rosa. A. veneta, Rosa, Boll. Mus. Zool. Torino, 1886, No. 3. A. subrubicunda, forma hortensis, MicHarLsen, J. B. Hamb. wiss. Anst., vii, 1890, p. 15. A. (Notogama) veneta, Rosa, Boll. Mus. Zool. Torino, 1893, No. 160, p. 2. A. hibernica, Frizunp, P. R. Irish Ac., 1893, p. 402. Definition. Length, 70 mm.; breadth, 5 mm.; number of segments, 153. Clitellum, AXVI, XXVIU-XXXIT, XXXII. Setae paired but not strictly, the setae of ventral pair more separated than those of dorsal pairs. Tubercula pubertatis on XXX, XXXI. Sperma- thecae, two pairs in IX, X, opening posteriorly. Hab.—Venice ; Argentina ; Portugal ; Palestine. The species comes very near to A. foetida, with which it agrees absolutely in colour. It is to be distinguished by the position of the tubercula pubertatis. The spermathecae open close to the dorsal middle line as in the species mentioned. The Portuguese specimens form a variety which is marked by its smaller size and by the more strictly paired setae. This same variety is found in Liguria and in the Argentine (whither it has been probably accidentally imported). It is not certain whether A. submontana of VEsDovsKY is really different. The clitellum seems to have a different position (i.e. xxiv—xxxiii), but the structure of the worm is not fully known. (27) Allolobophora syriaca, Rosa. A. syriaca, Rosa, Mem. R. Acc. Torino, 1893, p. 65. Definition. Length, 130 mm.; diameter, 9 mm.; number of segments, 210. Setae distant: 1-2= 3-4, both>2-3. Clitellum, XXVI-XXXII. Tubercula pubertatis, XXVII-XXXI. Dorsal pores commence IV/V or V/VI. Sperm-sacs two pairs in XI, XII. Spermathecae absent. Hab—Samsun in Asia Minor. Three examples of this species from the Imperial Museum at Vienna were studied by Rosa, who adopted Cart Wessexzy’s MS. name. (28) Allolobophora mima, Rosa. A. mima, Rosa, Boll. Mus. Zool. Torino, 1889, No. 63. Definition. Length, 240 mm.; diameter, 12 mm. 5 number of segments, 260, Setae distant, 1-2=2-3 > 3-4. Clitellum, XXVIII (XXIX)-XL (XLII), Tubercula pubertatis, 4¥ 714 OLIGOCHAETA AXVITT (XXIX-XL), XLI. Dorsal pores commence XILI/XIV. Spermathecae in VI-XI, opening posteriorly im line with seta 3. LHab.—ltaly and South Austria, (29) Allolobophora samarigera, Rosa. A. (Dendrobaena) samarigera, Rosa, loc. cit., p. 5. Definition. Length, 80 mm.; diameter, 9 mm.; number of segments, 140. Setae distant. Clitellum, XXVITI-XXXIV. Tubercula pubertatis absent. First dorsal pore, IT/V. Sperm-sacs in IX, XI, XII. No spermathecae. Hab.—Pulestine. (30) Allolobophora patriarchalis, Rosa. A. patriarchalis, Rosa, loc. cit., p. 9. Definition. Length, 75 mm.; diameter, 5 mm.; number of segments, 160. Setae strictly paired. Clitellum, XXII-XXXIII. Tubercula pubertatis, XXXI, XXXII. First dorsal pore, IV/V, Sperm-sacs in XI, XII. Spermathecae in Xx, ATI, opening anteriorly by dorsal seta. Hab.—Palestine. (31) Allolobophora semitica, Rosa. A. (Dendrobaena) semitica, Rosa, loc. cit., 1893, No. 160, p. 3. Definition. Length, 70mm. ; diameter, 7mm.; number of segyments,140. Setae distant. Clitellum, XXVI-XXXILI. Tubercula pubertatis, XXXI, XXXII (XXXIIL). First dorsal pore, V/VI. Sperm-sacs in IX, XI, XII. Spermathecae in X, XI, opening anteriorly in line with seta’ 3. Hab.—Palestine, ‘ (32) Allolobophora byblica, Rosa. A. (Dendrobaena) byblica, Rosa, loc. cit., p. 4. Definition. Length, 40 mm.; diameter, 4mm. ; number of segments, 100. Setae distant. Chi- tellum, XXV-XXX, Tubercula pubertatis on XXVI-XXVILT. Dorsal pores commence X/XI. Sperm-sacs in IX, XI, XII. Spermathecae in X, XI, opening anteriorly in line with seta 4. Hab.—Palestine. (33) Allolobophora rosea (Savieny). Enterion roseum, Savicny, Mém. Ac. Roy. Inst. Fr. (Analyse), v, 1826, p. 182. Lumbricus roseus, Ducks, Ann. Sci. Nat., (2) viii, 1837, p. 20. DESCRIPTIONS OF GENERA AND SPECIES 715 - communis, HorrmrisrEr, Die bisj. bek. Art. Regenw., 1845, p. 27 (in part.). . mucosa, Ersen, Ofv. Svensk. Acad., 1874, No. 2, p. 47. . aquatilis, VeJDovsky, SB. Béhm. Ges., 1875, p, 199. mucosus, TAUBER, Ann. Dan., 1879, p. 16. carnea, VEJDOVSKY, Syst. u. Morph., 1884, DP 61. - aquatilis, OzRLEY, Ert. termesz. Kér., xv, 1885, p. 28. . (Allolobophora) carneus, VAILLANT, Annelés, p. 136. . (Allolobophora) roseus, VAILLANT, Annelés, p. 137. rosea, Rosa, Mem. R. Acc. Torino, 1893, p. 31. : . (Notogama) rosea, Rosa, Boll. Mus. Zool. Torino, 1893, No. 160, p. 2. PPP PPP HEP Definition. Length, 60 mm.; diameter, 4mm.; number of segments, 150. Setae strictly paired. Clitetlum, XXV (XXVI)-XXXII, Tubercula pubertatis, XXIX-XXXI (XXIX,° XXX ). Dorsal pores begin IV. V. Spermatheca in X, XT, opening anteriorly near to middle dorsal line. Hab.—Europe ; Palestine; Siberia ; Morocco ; N. America ; Argentine; Brazil. The above definition refers to the ‘subspecies typica’ of Rosa. A second sub- species is ‘macedonica, with a clitellum xxvi-xxxiii, from Macedonia. (34) Allolobophora nordenskioldii, E1sen. A. Nordenskiéldii, E1sey, K. Svensk. Akad. Handl., 1879, No. 7, p. 6. Lumbricus (Allolobophora) Nordenskioeldii, VAILLANT, Annelés, p. 146. Definition. Length, 150 mm.; number of segments, 125. Setae strictly paired. Clitellum, XXVI-XXXIT. = =Tubercula pubertatis, XXIX, XXX, XXXI. Hab.—Siberia ; Sweden ; Azores. This species appears to be coloured like A. foetida, and, according to Rosa (15), has an identical ornamentation upon the seta. The two are doubtfully distinct. (35) Allolobophora hermanni, MricHaz.sen. : A. Hermanni, Micuarusen, JB. Hamb. wiss. Anst., vii, 1890, p. 13. Definition. Length, 4omm.; breadth, 2mm. ; number of segments, 100. Tubercula pubertatis on XXIX, XXX. First dorsal pore IV/V. Setae are paired, though the two setae of each pair are more widely separated in anterior segments ; these setae also are larger than those which follow. Hab— Harz Mountains ; im a morass, This species appears to be without integumental pigment. 4x3 716 OLIGOCHAETA (36) Allolobophora georgii, MicHAE.sen. A. Georgii, MicnarLsen, JB. Hamb. wiss. Anst., vii, 1890, p. 3. Definition. Length, 29 mm.; breadth, 2 mm.; number of segments, 110. Clitellum, ANVIL, XXIX-XXXV. First dorsal pore IV/V. Tubercula pubertatis on XXXI, XXXII. Setae strictly paired. Spermathecae in X, XI, opening between IX/X, X/XI, im line with seta 4. Hab.—Valencia, Spain. This species comes nearest to A. trapezoides. (37) ii-iii>iii-iv. The irregular position of the spermathecae is due to the fact, that some of the pouches open anteriorly and others posteriorly; the first four open posteriorly on a line with seta 3; the fifth pair lies either in the ninth or in the tenth segment, in the first case against the hind wall of the segment; in one specimen these had an intermediate position projecting into two segments (cf. A. complanata, BepDARD, 18). The sixth pair opens by the front wall of the eleventh segment. (40) Allolobophora leoni, MicHartsen. A. Leoni, MicHAELsEn, loc. cit., p. 15. Definition. Length, go mm.; breadth, 5 mm.; number of segments, 156. Clitellum, XXTTI-XXXVT. First dorsal pore, IV/V. Tubercula pubertatis, XXX, XXXII. Setae paired, the ventral median interval is less posteriorly and greater anteriorly than the lateral, Spermathecae, eight to ten in each of segments X, XI. Hab.—dJassy. This species is not very fully described by MrcHartsen. Further details were added by Rosa (15). It is unpigmented, like A. trapezoides. The post-clitellian region of the body is angular; the segments of the anterior part of the body are tri-annulate. It appears to be uncertain whether the clitellum does not extend as far as to the thirty-ninth segment ; Rosa, however, only found it to occupy xxvi-xxxiv. The ventral setae of segments xii, xiii, xxii lie on slightly raised papillae. (41) Allolobophora jassyensis, MicHartsey. A. jassyensis, MICHAELSEN, loc. cit., 1891, p. 17. Definition. Length, 95 mm.; breadth, 4 mm.; number of segments, 133. Clitellum, XXVIII, XXIX-XXXV. Tubercula pubertatis, XXXI-XXXV. — Setae strictly paired. 718 OLIGOCHAETA First dorsal pore, IV/V. Spermathecae in IX, X, opening between IX/X, X/XI. Hab.— Jassy ; Palestine. In the above definition I have, as usual, given the greatest length and the greatest number of segments of the individuals studied by the describer of the species. It is a remarkable fact that the smallest specimen, measuring only 58 mm, in length, had the largest number of segments, while the largest specimen had the fewest segments. The ventral setae of the segments x, xi, xili, xxvii, are upon strongly marked papillae ; these papillae appeared to be quite constant in the species. Only two pairs of sperm- sacs were found lying in xi, xii, According to Rosa two tubercula occupy xxxii-xxxiv, and the spermathecae are in x, xi. The sperm-sacs are four pairs. (42) Allolobophora japonica, MIcHAELSEN. A. japonica, Micuartsen, Arch. f. Nat., 1892, p. 230. Definition. Length, 42 mm.; breadth, 24 mm.; number of segments, 126. Clitellum, AXIV-XXXI. Setae strictly paired, separated by equal mlervals. First dorsal pore, IV/V. Tubercula pubertatis, XXVIL, XXIX. Spermathecae two pairs in IX, X, opening between IX/X, X/XI, in line with lateral setae. Hab—Japan. Of this species there appear to be two varieties, which are only to be distinguished by colour and size. I have selected the smaller form for description as the type, for the reason that it comes first in MIcHAELSEN’s account of A. japonica. This form is colourless; the larger worms are a darkish red in colour, and measure 130 mm. in length by a diameter of 5mm.; the body is composed of 155 segments. In both forms the setae of the hinder end of the body are rather larger than those in front. There are besides the tubercula pubertatis several papillae; two pairs of these lie upon segments xxii, xxv. Those of the first segment are in line with the ventral setae, the second pair more dorsal in position. (43) Allolobophora madeirensis, MicHar.sen. A. madeirensis, MICHAELSEN, loc. cit., 1891, p. 206. Definition. Length, 47 mm.; diameter, 5 mm.; number of segments, 135. Setae not strictly paired. Clitellum, XXXII-XXXVI. Tubercula pubertatis, XXXIII-XXXV. Dorsal pores begin ILIIF. Hab.—Madeira ; Portugal. (44) Allolobophora dubiosa, OERLEY. Criodrilus dubiosus, OsRLEY, MT. Akad. Math., xvi, 1880, p. 603. A. dubiosa, OERLEY, Ert. termesz. Kor. xv, 1885, p. 24. DESCRIPTIONS OF GENERA AND SPECIES 719 Definition. Length, 180 mm. ; number of segments, 250. Colour a dark, green reddish below ; clitellum flesh-colowred. Setae strictly paired. Clitellum, XXXVII-XLV1. Hab.— Hungary ; in marshy spots. This species, as will be evident from the above, is but ill-defined. Rosa (15, p. 55) considers that. the tubercula pubertatis are in the form of a continuous ridge along the clitellum, which is referred to by OrRuey, though the latter states that there are no tubercula. The position of the clitellum, however, coupled with the strictly paired setae seems to mark out the species as distinct. (45) Allolobophora mediterranea, Oxrrzy. A. mediterranea, OERLEY, Zool. Anz., 1881, p. 286. Definition. Length, 120 mm.; number of segments,120. Setae strictly paired. Clitellum, ° AXITI-XXXI. Tubercula pubertatis on XXIX, XXX, XXXI. Hab.—Balearie Isles. (46) Allolobophora frivaldszkyi (Ozztey). Lumbricus terrestris, var. gigas, OERLEY, MT. Akad. Math. xvi, 1880, p. 582. Octolasion Frivaldszkyi, OERLEY, Ert. termesz. Kor., xv, 1885, p. 17. Definition. Length, 360 mm.; diameter, 20 mm.; number of segments, 260. Setae distant: 1-2 >2-3 and 3-4. Chtellum, XXVIL-XXXV. Tubercula pubertatis, XXVIII-XXXP. Hab.— Hungary. (47) Allolobophora gracilis (OERLEy). Octolasion gracile, OERLEY, Ert. termesz. Kor., xv, 1885, p. 18. Definition. Length, 70 mm. ; number of segments, 180. Setae not strictly paired. Clitellum, XXX-XXXV. Tubercula pubertatis, XXX-XXXV. Hab-—Hungary and Holland. This species is evidently, as Rosa (15, p. 63) suggests, near to A. cyanea. Octolasion rubidwm of OrRLEY (2) is probably merely a variety of this species, as Rosa (15, p. 64) has pointed out. Its clitellum and tubercula are exactly the same in position and extent; it was met with in Hungary and at Woolwich. The prostomium is stated to be larger and to occupy two-thirds instead of one-half of the buccal segment, but no salient points of difference can be extracted from the description. As Rosa, who has had so much experience in this family, recognizes the species ‘rubida’ (though as he points out its name will have to be changed) I prefer to leave the matter undecided. 720 OLIGOCHAETA (48) Allolobophora nasonovii, Kuacin. Dendrobaena nasonovii, KuLAGIN (fide Rosa, 15). Definition. Length, 90 mm.; number of segments, 170. Setae in eight rows. Clitellum, AXV-XXIX, Hab.—Suchum. This species is, as Rosa (15, p. 45) points out, close to A. platyura; but he holds it to be probably distinct; it is evidently but ill defined. (49) Allolobophora bogdanovii, Kuxacetn. A. Bogdanovii, Kunacin (fide Rosa, 15). Definition. Length, 662 mm. ; number of segments,110. Setae distant. ' Clitellum, XXV—-XXX. Tubercula pubertatis, XXVIII, XXIX, XXX. Hab.—Suchum. (50) Allolobophora caucasica, Kuxaatn. Dendrobaena caucasica, KuLAain (fide Rosa, 15). Definition. Length, 40 mm. ; number of segments, go. Colour dark red, darker above than below. Setae in eight rows, equidistant. Prostomium completely dividing buccal segment. Clitellum, XXV, XXVI-XXIX, XXX, XXXI. Dorsal pores commence IV/V. Hab.—Kacila, in the Caucasus (2,200 ft.). This is another doubtful form, of whose internal structure nothing is known. (51) Allolobophora oerleyi, Horst. Enterion platyurum, Firzincer, Isis, 1833, p. 552 (in part.). Lumbricus terrestris, var. platyurus, OERLEY, MT. Akad. Math., xvi, 1880, p. 583 (in part.). Octolasion platyurum, OERLEY, Ert. termesz. Kor., xv, 1885, p. 18 (in part.). A. Oerleyi, Horst, Notes Leyd. Mus., ix, 1887, p. 294. A. platyura, var. depressa, Rosa, Mem. R. Ace. Torino, 1893, p. 44. Definition. Length, 111 mm.; number of segments, 130. Setae distant. Clitellum, XXV- XXX. Tubercula pubertatis, XXVI-XXVIII, Male pores inconspicuous. Spermathecae in VIT-X, opening posteriorly by seta IV. Hab.—EKurope. Horst found some variation in the number of spermatheeae, there being sometimes only three or four pairs. a DESCRIPTIONS OF GENERA AND SPECIES 721 (52) Allolobophora fitzingeri, Brppaxp. Enterion platyurum, FirzinaeEr, Isis, 1833, p. 552 (in part.). Lumbricus terrestris, var. platyurus, OzrLEy, MT. Akad. Math., xvi, 1880, Pp. 583, (in part.). Octolasion platyurum, OERLEY, Ert. termesz. Kor., xv, 1885, p. 18 (in part.). A platyura, var. typica, Rosa, Mem. R. Ace. Torino, 1893, p. 43. Definition. Length, 111 mm.; number of segments, 153. Setae distant. Clitellum, XXV-XXX. Lubercula pubertatis, XXVI-XXVIIT, XXIX. Male pores inconspicuous. Spermathecae ’ im X, XI, opening anteriorly by seta IV. Hab.—Europe. Rosa speaks of two varieties or subspecies—typica and depressa. The latter I place, as Rosa was inclined to think should be done, in a distinct species. The worms called ‘platyurwm’ by FitztnezR were found (by WessELEY) to consist of these two subspecies, to both of which the (imperfect) diagnosis of FrTzincER applies. The name of A. oerleyi must be applied to the species ‘depressa.’ Accordingly, I propose to call this worm by the above name. Genus LUMBRICUS, EISEN. DEFINITION. Prostomium completely divides buccal segment. Setae strictly paired. Longer, straighter setae on clitellum. A median seminal reservoir, extending through segments X, XI, present, into which open three pairs of sperm-sacs. Spermathecae always two pairs in IX and X. Rosa recognizes (15, p. 22) eight species of the genus, which form a remarkably graduated series, in respect of the segments which bear the tubercula pubertatis. I repeat here the table which he gives in illustration of this: — 1. (Variation of L. rubellus) . . 27, 28, 29, 30 L. rubellus . . . 28, 29, 30, 31 L. castaneus . . « 29, 30, 31, 32 L. meliboeus . . . « «. 30, 31, 32, 33 DL. tyrtaeus . 1. « » 6 + + 31, 32, 33, 34 (Form wanting) . . . . . .' (32, 33) 34 35) L. hereuleus. . . 1 1 es ee + 33s 34 35, 36 L. papillosus «1 6 6 ee ee + 34, 35s 36, 37 ; L. festivus 6 6 ee eee ee ee ee BSS 36, 37, 38 L. polyphemus . 62 en EE a? Oe Per anWsa YD 40, 41, 42, 43, 44, 45. = 9° ao 722 OLIGOCHAETA It will be observed that one form only is wanting to complete the symmetry of the first seven species, if, that is to say, we allow L. tyrtaews of Savicny and L. papillosus of FRIEND. (1) Lumbricus rubellus, Horrmeister. L. rubellus, HoFFMEISTER, Arch. f. Nat. 1843, p. 187. Enterion rubellum, OrRLEY, MT. Akad. Math. xvi, 1880, p. 588. L. (Lumbricus) rubellus, VAILLANT, Annelés, p. 126. Definition. Length, 120 mm.; diameter, 6 mm.; number of segments, 120. Colour, red brown or purple. Clitellum, (XXVI) XXVII-XXXIL. Tubereula pubertatis, XXVIII, XXIX, XXX, XXXI. First dorsal pore, VII/VII, Male pores almost invisible. Hab.— Europe; N, America; Siberia; Nicobar; New Zealand. Rosa (15) describes the colour as ‘bruno rossiccio. In my New-Zealand examples it is distinctly purple, as in the next species. The clitellum, however, agrees with that of ZL. rwbellus, rather than with that of ZL. castaneus. ' (2) Lumbricus castaneus (Savicny). Enterion castaneum, Savieny, Mém. Ac. Roy. Fr. Inst. (Analyse), v, 1826, p. 180. E. pumilosum, SAVIGNY, ibid., p. 181. Lumbricus castaneus, Duais, Ann. Sci. Nat. (2), vili, 1837, p. 22. L purpureus, E1sen, Ofv. Svensk. Akad. 1871, No. Jo, p. 956. Definition. Length, 500 mm.; diameter, 4 mm.; number of segments, 90. Colour chestnut or violet brown. Clitellum, XXVITI-XXXIII. Tubercula pubertatis, XXIX, XXX, XXX, ANXIT, First dorsal pore, VI/VII. Hab.—Europe ; N. America. This species, like the last, has almost invisible male pores, owing to the absence of a glandular swelling, such as characterizes so many Lumbricidae. The prostomium has a transverse furrow, often (but not always) wanting in L. rubellus. It is apparently only to be distinguished by the different position of the clitellum and the tubercula pubertatis. . (3) Lumbricus meliboeus, Rosa. L. meliboeus, Rosa, Lombr. Piemont., 1884, p. 21. Definition. Length, go mu.; diameter, 5 mm.; number of segments. 124. Colour violaceous, DESCRIPTIONS OF GENERA AND SPECIES 723 with a median darker streak posteriorly. Clitellum, XXIX-NXXIII. Tubercula pubertatis on XXX, XXXI, XXXII, XXXII. First dorsal pore, VII/VIII, Hab.—Piedmontese Alps. The spermathecae are stated to occur in segments viii and ix, which is, of course, an unusual position for them to occupy in this genus. The male pores are well- marked externally. (4) Lumbricus polyphemus (Frrzincer). Enterion Polyphemus, FirzincER, Isis, 1833, p. 552. L. Polyphemus, Ducts, Ann. Sci. Nat., (2) viii, 1837, p. 21. Definition. Length, 180 mm.; diameter, 8 mm.; number of segments, 130. Clitellum, XXXIX-XLIV. = Tubercula pubertatis, XL, XLII, XL, XLII, XLIV. Male pores almost invisible. Hab.—Austria. The above description is taken from Rosa’s (15) definition of the species. The identification with Firzincer’s species is rendered certain by a comparison (CARL WESSELY quoted by Rosa) with Firzincer’s type. , (5) Lumbricus festivus (SAvieny). Enterion festivum, Saviany, Mém. Ac. Roy. Inst. Fr. (Analyse), v (1826), p. 180. L. festivus, Duaks, Ann. Sci. Nat. (2), vili, 1837, p. 21. L. rubescens, FRIEND, Nature, 1891, p. 273. Definition, Length, 100 mm.; diameter, 5 mm.; number of segments, 120. Colour, bright red brown, Clitellum, XXXIV-XXXIX. Tubercula pubertatis, XXXV, XXXVI, XXXVI, XXXVI. First dorsal pore, V/VI. Male pores with swollen lips. Hab—KEngland ; France. (6) Lumbricus papillosus, FRrEnp. L. papillosus, Frrenp, P. R. Irish Ac. (3), ii, p. 453- Definition. Length, 100 mm.; diameter, 8 mm.; number of segments, 130. Colowr, ruddy brown. Clitellum, XXXILI-XXXVII. Tubercula pubertatis, XXXIV, XXXV, XXXVI, XXXVIL. First dorsal pore, IX/X. Hab.—lIreland. 422 724 OLIGOCHAETA (7) Lumbricus herculeus (Savieny). Enterion herculeum, Saviany, Mém. Roy. Ac. Inst. Fr. (Analyse), v, 1826, p- 188. L. herculeus, Ducks, Ann. Sci. Nat., (2) viii, 1837, p. 21. L. agricola, HorrMEisTER, De verm. quibusd. 1842, p. 24 (in part.). L. terrestris, Etsen, Ofv. Svensk. Akad., 1871, No. 10, p. 954. Definition. Length, 360 mm.; number of segments, 180. Clitellum, XXXII-XXXVII. Tubercula pubertatis, XXXIIJ-XXXVI._ First dorsal pore, VII/VIII. Male pores conspicuous, Hab.—Northern Europe; N. America; Siberia. BIBLIOGRAPHY TuE following list of books and papers contains all that has been referred to in the foregoing pages. I have, indeed, endeavoured to make it as complete a list as possible of the literature of the group. I believe that no paper of importance has been omitted, but I have not attempted to include textbooks, or every paper of a ‘preliminary’ nature, or in which the Oligochaeta are mentioned without the recording of new facts. With a few exceptions (marked by an asterisk), every quotation has been verified by myself. Anperson, H. H. Anoplophrya aeolosomatis, a new ciliated Infusorian parasitic in the Alimentary canal of Aeolosoma chlorostictum, W.-M. MSS. J. A. S. B., lvii, pp. 381- 383, PL i. Anprews, E, A. Bifurcated Annelids. Am. WNat., xxvi, pp. 725-733, Pl. xxi. Arxinson, G. F. A Remarkable Case of Phosphorescence in an Earthworm. Am. Nat., xxi, PP: 773, 774- Barr, K. E. v. Beitrage zur Kenntniss der niederen Thiere. Nov. Act. Nat. Cur., xiii, pp. 614, 655, 656; Pl. xxix, figs. 23, 24. Barrp, W. (1) Description of a New Species of Earthworm (Megascolex diffringens), found in North Wales. P. Z. S., 1869, pp. 40-43; four cuts. (2) Additional Remarks on the Megascolex diffringens. Ibid., pp. 387-389. (83) Description of some New Species of Annelida and Gephyrea, in the Collection of the ' British Museum. J. Linn. Soc., xi, pp. 94-97. * BatsaMo-CRIVELLI, G. (1) Catalogo degli Annelidi; in Notizie naturali, ecc., sulla provincia di Pavia. Pavia, 1864. (2) Sopra una Nuova Specie di Naide. Giorn. Ist. Lomb., ii, pp. 11, 12. Barrors, T. Sur la présence du Lwmbricus (Photodrilus) phosphoreus, Ducus, a Grofiliers (Pas-de- Calais). Rev. Biol., iii, pp. 117-119. Bet, F. J. Notice of two Lumbricit with Bifid Hinder Ends. Ann. Mag. Nat. Hist., (5) xvi, PP: 475-477 5 cuts. : Brarnvitty, H. Mémoire sur la classe des Sétipodes, &c. Bull. Soc, Phil. Paris, 1818, pp. 78-85. ; Botstus, H. Notice sur lanatomie de l’organe segmentaire d’Enchytraeides. Anat. Anz., viii, pp. 210-215. 726 OLIGOCHAETA Breppagp, F. E. (1) On the Anatomy and Histology of Plewrochaeta Moseleyi (Abstract). P.R. Soc. Edinb., xi, pp. 629, 630. (2) On the Anatomy and Histology of Plewrochaeta Moseleyi. Tr. R. Soc. Edinb., xxx, pp. 481-509, Pls. xxv—xxvii. (8) Note on the Structure of the Body-Wall in certain Earthworms. P. R. Phys. Soc. Edinb., viii, pp. 89-91. (4) Note on some Earthworms from India. Ann. Mag. Nat. Hist., (5) xii, pp. 213-224, Pl. viii. (5) On the Genus Megascolex of Tempreron. Ann. Mag. Nat. Hist., (5) xiii, pp. 398-402. (6) Notes on the Structure of a New Species of Earthworm belonging to the Genus Acanthodrilus (E. P.). P. R. Phys. Soc. Edinb., viii, pp. 369-377. (7) On the Structure and Systematic Position of a gigantic Earthworm from the Cape Colony (Microchaeta rappii). Tr. Z. S., xii, pp. 63-76, Pls. xiv, xv. (8) On the Specific Characters and Structure of certain New Zealand Earthworms. P. Z. S., 1885; pp. 810-832, Pls. lii, liii, and three cuts. (9) Note on the Structure of a large Species of Earthworm from New Caledonia. P. Z. 8., 1886, pp. 168-175, Pl. xix. (10) Preliminary Note on the Nephridia of a New Species of Earthworm. P. R. Soc., No. 238, pp. 459-464. (11) Note on the Paired Dorsal Vessel of certain Earthworms. P. R. Phys. Soc. Edinb., vill, pp. 424-430, Pl. xxii. (12) Note on the Nephridia of a Species of Acanthodrilus. Zool. Anz., viii, pp. 289, 290. (13) Observations on the Structure of Lumbricus complanatus. P. &. Soc. Edinb., xiii, Pp. 451-460 ; two cuts. (14) On the Reproductive Organs in the Genus Zudrilus (H. P.). P. R. Soc. Edinb., xiii, pp. 672-682, Pl. xxv. (15) Notes on some Earthworms from Ceylon and the Philippine Islands, including ‘a Description of two New Species. Ann. Mag. Nat. Hist., (5) xvii, pp. 89-98, Pl. ii. (16) Contributions to our Knowledge of the Oligochaeta. Hep. Brit, Ass. 1885, p. 1102, 3. (17) Sur les organes segmentaires de quelques vers de terre. Ann. Sei. Nat., (7) xix, pp. 1-18, Pl. i. (18) On- the Anatomy, Histology, and Affinities of Phreoryctes. Tr. R. Soc. Edinb., xxxv, pp. 629-640; one plate. (19) Observations upon the Structure of a Genus of Oligochaeta belonging to the Limicoline Section. Zr. R. Soc. Hdinb., xxxvi, pp. 1-17; one plate. (20) On the Anatomy of Ocnerodrilus (Eisrn). Tr. R. Soc. Hdinb., xxxvi, pp. 563-583; one plate. (21) Anatomical Description of Two New Genera of Aquatic Oligochaeta. Tr. BR. Soc., — Edinb., xxxvi, pp. 273-305; three plates. (22) Contributions to the Natural History of an Annelid of the Genus Dero. P. Z. 8., 1889, pp. 440-444; six cuts. (23) Some new or little-known Oligochaeta. P. &. Phys. Soc. Edinb., xii, pp. 30-45 ; three cuts. BIBLIOGRAPHY 727 Bepparp, F. E. (continued), (24) Abstract of some Investigations into the Structure of the Oligochaeta. Ann. Mag. Nat. Hist., (6) vii, pp. 88-96; two cuts. (25) On some Aquatic Oligochaetous Worms. P.Z. S., 1892, PP. 349-361 ;" two cuts. (26) The Classification and Distribution of Earthworms. P. R. Soc. Phys. Edinb., x, 1890-91, pp. 235-290, Pls. xiii, xiv (maps). (27) Note upon the Encystment of Aeolosoma. Ann. Mag. Nat. Hist. (6) ix, pp. 12-19 ; two cuts. (28) The Earthworms of the Vienna Museum. Ann. Mag. Nat. Hist., (6) ix, pp. 113-134, Pi. vii. (29) On a new Genus of Oligochaeta, comprising five New Species belonging to the Family Ocnerodrilidae. Ann. Mag. Nat. Hist., (6) x, pp. 74-97, Pls. vi, vii. (80) On some Perichaetidae from Japan. Zool. Jahrb., vi., Abth. f. Syst. pp. 755-766, : Pl. xxxii. (81) On the possible Origin of the Malpighian Tubules in the Arthropoda. Ann. Mag. Nat. Hist., (6) iv, pp. 290-292. (32) Notes upon certain Species of Acolosoma. Ann. Mag. Nat. Hist., (6) iv, pp. 262-265. (33) On the Homology between Genital Ducts and Nephridia in the Oligochaeta. P. R. Soc., xlvili, pp. 452-455. (34) Observations upon the Structure of a Genus of Oligochaeta belonging to the Limicoline Section. (Abstract.) P. R. Soc. Hdinb., xvii, 1889-90, pp. 5-7. (85) Preliminary Notice of a New Form of Excretory Organs in an Oligochaetous Annelid. P. R. Soc., xlix, pp. 308-310. (86) On an Earthworm of the Genus Siphonogaster from West Africa. P. Z. S., 1891, pp. 48-52; six cuts. (87) On the Oligochaetous Fauna of New Zealand, with preliminary descriptions of New Species. P. Z. S., 1889, pp. 377-382. (88) On the Earthworms collected in Algeria and Tunisia by Dr. Anderson. P. Z. S., 1892, pp. 28-37; two cuts. (39) Two New Genera and some New Species of Earthworms. @. J. .S., (n.8.) xxxiv, pp, 243-278, Pls. xxv, xxvi. (40) Preliminary Account of an Earthworm from West Africa referable to a new Genus. _ P.Z.8., 1891, pp. 172-176. (41) Descriptions of some new or little-known Earthworms, together with an account of the Variations in Structure exhibited by Perionyx ewcavatus, E. P. P. Z. 8S, 1886, pp. 298-314; six cuts. (42) Article, ‘Worm.’ ncycl. Brit., 9th edition. . (43) Contributions to the Anatomy of Earthworms, with descriptions of some New Species. Q. J. M.S., (n. 8.) xxx, pp. 421-479, Pls. xxix, xxx. (44) On the Structure of a Species of Earthworm belonging to the Genus Diachaeta. Q. J. M. S., (n.s.), xxxi, pp. 159-174, Pl. xx. (45) On Certain Points in the Structure of Urochaeta, E. P., and eee nov. gen., with further Remarks on the Nephridia of Earthworms. @Q. J. M. S., (n. 8.) xxix, pp. 235-282, Pls. xxiii, xxiv. 728 OLIGOCHAETA Bepparp, F. E. (continued). (46) (47) (48) (49) (50) (51) (52) (53) (54) (55) (58) (57) (58) (59) (60) (61) (62) (63) (64) (68) (68) On the Anatomy of Allurus tetraedrus (E1sen). Q. J. M.S., (n. 8.) xxvili, pp. 365-371, Pi. xxv. On the Occurrence of Numerous Nephridia in the same segment in certain Earthworms and on the Relationship between the Excretory System in the Annelidae and in the Platyhelminths. Q. J. M8, (n. s.), xxviii, pp. 397-411, Pls. xxx, xxxi. On the Structure of Three New Species of Earthworms, with Remarks on Certain Points in the Morphology of the Oligochaeta. Q. J. M.S., (n.s.) xxix, pp. 101-131, Pls. xii, xiii. A Zoological Notes. (I) On some British Species of Pachydrilus. P.R. Phys. Soc. Hdinb., x, pp. 101-106, Pl. v. Zoological Notes. (II) Aquatic Earthworms. P. R. Phys. Soc. Edinb., x, pp. 208-210. Researches into the Embryology of the Oligochaeta. (I) On certain Points in the Development of Acanthodrilus multiporus. Q. J. M.S8., (n.s.) xxxiii, PP. 495-540, Pls. xxx, xxxi. On the Structure of an Earthworm allied to Nemertodrilus, Micu., with Observations on the Post-embryonic Development of Certain Organs. Q. J. I. S., (nu. 8.) xxxii, pp. 539-586, Pls. xxxvili. xxxix. On the Structure of a New Genus of Oligochaeta (Deodrilus), and on the Presence of Anal Nephridia in Acanthodrilus. Q. J. M. S., (nu. s.) xxxi, pp. 467-488, Pls. Xxxill, xxxliia. On the Structure of Two New Genera of Earthworms belonging to the Eudrilidae, and some Remarks on WNemertodrilus. @Q. J. M. S., (u.8.) xxxii, pp. 235-278, Pls. xvi-xx. On some Species of the Genus Perichaeta (sensu stricto). P. Z. 8., 1892, pp. 153-172, Pls. ix, x. Observations upon an American Species of Perichaeta, and upon some other Members of the Genus. P. Z. S., 1890, pp. 52-69, Pls. iv, v. On some new Species of Earthworms from various Parts of the World. P. Z. 8., 1892, pp. 666-706, Pls. xlv, xlvi; six cuts. : A New Branchiate Oligochaeta (Branchiura Sowerbii). Q. J. M. &., (n.s.) xxxill, pp. 1-17, Pl. xix. : Note on the Ovaries and Oviducts of Hudvilus. Zool. Anz., ix, pp. 342-344. On the Structure of a new Genus of Lumbricidae (Thamnodrilus gulielmi). P. Z. S., 1887, pp. 154-163; six cuts. Observations on the Structural Characters of certain new or little-known Earthworms. P. R. Soc. Edinb., xiv, pp. 156-176, Pl. v. : Contributions to the Anatomy of Earthworms, Nos. i, ii, ili. P. Z. S., 1887, pp. 372-392, Pl. xxxiii; three cuts. Contributions to the Anatomy of Earthworms, No. iv. P. Z. S., 1887, pp. 544-548 ; one cut. Note on the Structure and Development of the ovum in an Annelid. J. Anat. Phys., xxii, pp. 9-14, Pli. Preliminary Note on the Nephridia of Perichaeta. P. R. Soc., xliii, pp. 309-310. Note on the Reproductive Organs of Moniligaster. Zool. Anz., x, pp. 678-681. BIBLIOGRAPHY 729 Brpparp, F. E. (continued). (67) On the so-called Prostate Glands of the Oligochaeta. Zool. Anz., x, pp. 673-675. (68) Observations upon an Annelid of the Genus Acolosomu. P. Z. S., 1888, pp. 213-217, Pl. xii. (69) On the Reproductive Organs of Phreoryctes. Ann. Mag. Nat. Hist., (6) i, pp. 389-395, Pl. xxiii. (70) On certain Points in the Structure of Clitellio (CiaparhpE). P. Z.S., 1888, pp. 485-495, Pl. xxiii; two cuts. (71) Preliminary Note on the ‘Mucous Gland’ of Urochaeta. Zool. Anz., xi, PP- 99, 91. (72) Preliminary Notes on the Anatomy of Perichaeta, Zool. Anz., xi, pp. 91-94. (73) Further Notes upon the Reproductive Organs of Zudrilus. Zool. Anz., xi, pp. 643-646. (74) Note upon the Green Cells in the Integument of Aeolosoma. P. Z. S., 1889, xvi, pp, 51-56, Pl. v. (75) On the Anatomy and Histology of Phreoryctes. (Abstract.) P. R. Soc. Edinb., xvi, pp. 117-119. ; (76) Note on the Marine Oligochaeta of Plymouth. J. Mar. Biol. Ass., (n.s.) i, pp. 69-71. (77) Preliminary Note on a new Earthworm belonging to the family Eudrilidae. Zool. Anz., lil, pp. 561-563. (78) Preliminary Notes on some Oligochaeta. Zool. Anz., xii, pp. 533-536. (79) Preliminary Note upon Heliodrilus, a new Genus of Eudrilidae. Zool. Anz., xiii, pp. 627-629. (80) On the Atrium and Prostate in the Oligochaeta. P.Z.S., 1893, pp. 475-487; one cut. (81) A Contribution to the Anatomy of Sutroa. Tr. R. Soc. Hdinb., xxxvii, 1892, pp. 195-202 ; one plate. = (82) On the Geographical Distribution of Earthworms. P. Z. S., 1893, pp. 733-738. (88) Preliminary Notice of South American Tubificidae, &c. Ann. Mag. Nat. Hist., (6) xiii, pp. 205-210. (84) A Contribution to our Knowledge of the Oligochaeta of Tropical Eastern Africa. Q. J. M. S., (nu. 8.) xxxvi, pp. 201-269, Pls. xvi, xvii. (85) On Two New Genera, comprising Three New Species of Earthworms, from Western Tropical Africa. P. Z. S., 1894, pp. 379-399; three cuts. Benuam, W. B. (1) An Attempt to classify Earthworms. Q. J. U/. S., (n.8.) xxxi, pp. 201-315 3 zincographs. (2) Studies on Earthworms. Q. J. I. S., No. i (n.s.) xxvi, pp. 213-301, Pls. xv—xvibis. 63) es 5 3 No. ii (n.s.) xxvii, pp. 77-108, Pls. viii, ix. (4) * s <3 No. ili (u.s.) xxvii, pp. 561-572, Pl. xxxviii, figs. 9-19. (5) ‘Atrium’ or ‘Prostate.’ Zool. Anz., xiii, pp. 368-372; cuts. (6) The Nephridium of Zumbricus and its Blood-supply; with Remarks on the Nephridia in other Chaetopods. Q. J. Uf. S., (n.s.) xxxii, pp. 293-334, Pls. xxili-xxv. (7) A New English Genus of Aquatic Oligochaeta (Sparganophilus), belonging to the family Rhinodrilidae. Q. J. . S., (u.s.) xxxiv, pp. 155-179, Pls. xix, xx. (8) Descriptions of Three New Species of Earthworms, P. Z. S., 1892, pp. 136-152, Pls, vii, viii. (9) Notes on some Aquatic Oligochaeta, @Q. J. M.S, (n.s.) xxiii, pp. 107-218. Pls. v—vii. 5A 730 OLIGOCHAETA Benuam, W. B. (continued). (10) Report on an Earthworm, collected for the Natural History Department of the British Museum, by Emrn Pasua, in Equatorial Africa. J. Roy. Micr. Soc., 1891, pp. 1-8, Pls. iii, iv. (11) An Earthworm from Ecuador (Rhinodrilus ecuadoriensis), Ann. Mag. Nat. Hist., (6) ix, pp. 237-246, Pl. x. (12) Recent Researches on Earthworms. Rep. Brit. Ass., 1887, pp. 749-750. (18) The Genera T'rigaster and Benhamia. Ann. Mag. Nat. Hist., (6) vi, pp. 414-417. (14) Oligochaeta in H. N. Ripizy’s Notes on Zoology of Fernando Noronha. J. Linn. Soc., XX, pp. 560-563. (15) Note on a New Species of the Genus Wais. Q. J. M. S., (n.s.) xxxiv, pp. 383-386, Pl. xxxiii (part). (16) Description of a New Species of Moniligaster from India. Q. J. M. S., (n.8.) xxxiv, - pp. 361-382, Pls. xxxii, xxxiii (part). (17) Note on a New Earthworm. Zool. Anz., xi, pp. 72-75. (18) Note on a Couple of Abnormalities. Ann. Mag. Nat. Hist., (6) vii, pp. 256-258, Pl. iii. (19) Notes on Two Acanthodriloid Earthworms from New Zealand. @Q. J. M.S. (n.s.) XXxill, pp. 289-312, Pls. xv, xvi. (20) Notes on the Clitellum of the Earthworm. Zool. Anz., xvii, pp. 53-55. Bereu, R. 8. (1) Neue Beitrige zur Embryologie der Anneliden. I. Zur Entwickelung und Differenzirung des Keimstreifens von Lumbricus. Zeitschr. wiss. Zool., 1, pp. 469-526, Pls. X1X—Xxi. (2) Vorléufige Mittheilung iiber die Geschlechtsorgane der Regenwiirmer. Zool. Anz., ix, Pp. 231-235. (3) Die Entwicklungsgeschichte der Anneliden mit besonderer Riicksicht auf das sog. mittlere Keimblatt und das Zentralnervensystem. Kosmos, ii, pp. 401-418. (4) Zur Bildungsgeschichte der Exkretionsorgane bei Criodrilus. Arb. Zool.-Zoot. Inst. Wirzburg, viii, pp. 223-248, Taf. xiii, xfv. (5) Untersuchungen iiber den Bau und die Entwicklung der Geschlechtsorgane der Regenwiirmer. Zettschr. wiss. Zool., xliv, pp. 303-332, Pl. xxi. (6) Neue Beitrage zur Embryologie der Regenwiirmer. Zool. Anx., xiii, pp. 186-190. Buarnvittr, H. D. pz. Art. Vers, Lombric Naiidéens. Dict. de Sci. Nat. 1823, 1828. Buancuarp, E. in Gay, C. Historia fisica y politica de Chile segun documentos adquiridos en esta republica durante doce afios de residencia en ella y publicada bajo los auspicios del supremo Gobierno, 1849, vol. iii, pp. 37-42. Buioomrie.p, J. (1) The General Features of the Development of the Spermatozoa in the Vermes, &c. Zool. Anz., lil, pp. 65-7. (2) On the Development of the Spermatozoa, Pt. i, Lumbricus. Q. J. M.S., (n.s.) xx, pp. 79-89, Pls. vi, vii. Borcx, C. Om 7 artsformer af Lumbricus terrestris. Vorh. Skand. Naturf. Kjébnhavn, 1840, PP. 273-4. Bouton, T. Notes on Two Rare Annelids. Jfidl. Nat., viii, pp. 117-118; two plates. BIBLIOGRAPHY 731 Bonnet, C. Traité d’Insectologie, ou Observations sur quelques espéces de Vers d’Eau Douce, qui, coupés par morceaux, deviennent autant d’animaux complets. Paris, 1745. Borztu, A. Sul rapporte fra i nefridii e le setole nei Lombrici anteclitelliani. Boll. Mus. Zool. Torino, ii, No. 27. Boso, L. A. G. Histoire Naturelle des Vers, &c. vol. i. pp. 233-258. Paris, 1824. Bourns, A. G. (1) On Chaetobranchus, 2 New Genus of Oligochaetous Chaetopoda. Q. J. MU. S., (n.s.), xxxi, pp. 83, 89, Pl. xii. (2) On Indian Earthworms: Pt. i. Preliminary Notice of Earthworms from the Nilgiris and Shevaroys. P. Z. 8., 1886, pp. 663-672. (3) Certain Earthworms from the Western Himalayas and Dehra Dun. J. 4. S. B, lviii, pp. 110-117, Pl. iii. (4) On Megascolew coeruleus, Tempteton, from Ceylon; together with a Theory of the Course of the Blood in Earthworms. @. J. M. S., (n. 8.) xxxii, pp. 49-87, Pls. vi-ix. (5) Notes on the Naidiform Oligochaeta; containing a Description of New Species of the Genera Pristina and Pterostylarides, and Remarks upon Cephalization and Gemmation as Generic and Specific Characters in the Group. @. J. MZ. &., (n-s.) XXX, Pp. 335-356, Pls. xxvi, xxvii. (6) On Budding in the Oligochaeta. Rep. Brit. Ass., 1886, pp. 1096, 7. BovusFietpD, E. C. (1) On Slavina and Ophidonais. J. Linn. Soc., xix, pp. 264-268, Pl. xxxiii. (2) On the Annelids of the Genus Dero. Rep. Brit. Ass., 1885, pp. 1097-8. (8) The Natural History of the Genus Dero. J. Linn. Soc., xx, pp. 91-106, Pls. ili-v. Braun, M. Ueber die Thitigkeit des Regenwurmes (Lumbricus terrestris, L.) fir die Frucht- barkeit des Erdbodens. SB. Dorpat. Naturf. Ges., vi, pp. 186-188. BRIDGEMANN. 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Q.J.A/.S., xv, pp.157,158 ; cuts. Roupe, E. (1) Die Muskulatur der Chaetopoden. Zool. Anz., vili, pp. 135-138. (2) Die Muskulatur der Chaetopoden. Zool. Beitrége, i, pp. 164-205, Pls. xxiv—xxvil. Rottzston, J. The Blood-corpuscles of the Annelids. J. Anat. Phys., xii, pp. 401-418. Roziz, J. On the Anatomy of the Nervous System in the Lwmbricus terrestris. Q.J. M.S., (n. 8.) iii, pp. 106-109, PI. viii, figs. 1-4. 5c 746 OLIGOCHAETA Rosa, D. (1) I Lombrichi raccolti nell’ isola Nias dal Signor E. Modigliani. Ann. Mus. Civ. Genova, (2a) vil, pp. 125-136. (2) Descrizione dell’ Allolobophora festae, nuova specie di Lumbricide. Boll. Mus. Zool. Torino, vii, No. 122. (3) Note sui Lombrichi iberici. Jbid., iv, No. 63. (4) Sull assenza dei Receptacula Seminis in alcuni Lumbricidi. J6d., iv, No. 71. (5) I Lombrichi della Spedizione Antartica del 1882. Ann. Mus. Civ. Genova, (2a) vii, pp. 137-146. (6) I Terricoli raccolti dal dott. Canto Spreazzini. Ibid., (2a) ix, pp. 509-521; one cut. (7) Sulla Struttura dello Hormogaster redii. Mem. R. Ac. Torino, (2), xxxix, 14 pp.; one plate. (8) Die exotischen Terricolen des k. k. naturhistorischen Hofmuseums. Ann. kh. hk, Nat. Hofm., vi, pp. 379-406, Taf. xiii, xiv. (9) Catalogo e Distribuzione Geografica dei Lumbricidi. Bull. Mus. Zool. Torino, iii, No. 151. (10) I Lombrichi raccolti nell’ isola di Engano dal Dottore E. Mopieniani. Jbid., (2a), xii, pp. 342-348. (11) Moniligastridi, Geoscolicidi ed Eudrilidi: in Viaggio di Lronarpo Fra. Ibid., ix, pp. 368-400, Pl. xii. (12) Sul Criodrilus lacuwm. Studio zoologico ed anatomico. Mem. R. Ac. Torino, (2), XXxVill, p. 16; one plate. (18) Kynotus michaelsent?, n. sp. (Contributo alla morfologia dei Geoscolecidi). Boll. Mus. Zool. Torino, vii, No. 119. (14) Descrizione dell’ Allolobophora smaragdina, nuova specie di Lumbricide. Jbid., vii, No. 130. (15) Revisione dei Lumbricidi. Mem, R. Ac. Torino, (2) xliii, pp. 1-50 ; two lith. tables. (16) Nota preliminare sul Criodrilus lacuum. Boll. Mus. Zool. Torino, i, No. 15. (17) Microscolex modestus (nu. gen., n.sp.). Ibid., ii, No. 19; three cuts. (18) Lombrichi dello Scioa. Ann. Mus. Civ. Genova, (2) vi, pp. 571-592, Tav. ix. (19) I Lumbricidi del Piemonte. 54 pp.; one plate. Torino, 1884. (20) Nuova classificazione dei terricoli (Lumbricidi sensu lato). Boll. Mus. Zool. Torino, iil, No. 41. (21) Allolobophora celtica, n.sp. Boll. Mus. Zool. Torino, i, No. 2. (22) Note sui Lombrici del Veneto (Riassunto). bid., No. 3. (23) ,, 5 » Atti R. Ist. Venet., (6) iv (1886), pp. 673-687. (24) Lumbricidi anteclitelliani in Australia. Boll. Mus. Zool. Torino, i, No. 18. (25) Sui generi Pontodrilus, Microscolex e Photodrilus. Ibid., iii, No. 39. (26) Perichetidi: in Viaggio di Leonarpo Fra in Birmania e Regione Vicine. Ann. Mus. Civ. Genova, (2a) vi, pp. 155-167, Tav. iii. (27) Perichetidi. (2nd part.) Ann. Mus. Civ. Genova, (2a) x, pp. 107-122, Pl. i. (28) Il Neoenchytraeus bulbosus, n.sp. Ibid., ii, No. 29. (29) Di un Nuovo Lombrico Italiano: Allolobophora Tellinii, n.sp. Ibid., iii, No. 44. (80) Lumbricidi in Viaggio del Dr. E. Festa in Palestina, nel Libano e Regioni Vicine. Ibid., viii, No. 60, 1893. (81) Sul Geoscolea maximus, Levcx. Ibid., iti, No. 40. BIBLIOGRAPHY 747 Rosa, D. (continued). (32) Hormogaster redii, n.g., n.sp. Ibid., ii, No. 32. (83) Sulla Struttura dell’ Hormogaster redii mihi (Riassunto). Ibid., iii, No 35. (34) La Distribuzione Verticale dei Lombrichi sulle Alpi. Jbid., ii, No. 31. (35) I Terricoli Esotici nell’ I. R. Museo di Storia Naturale di Vienna. Jbéd., vii, No. 114. (36) Lombrichi antarctici e Lombrichi di Nias (Sumatra). Ibid., iv, No. 73. (37) Allolobophora Ganglbaueri ed A. Oliveira, nuove specie di Lumbricidi europei. bid., ix, No. 170. (88) Descrizione del’ Allolobophora mima, n.sp. Ibid., iv, No. 60. Rosrnuor, Rosen v. Die monatlich herausgegebenen Insectenbelustigungen. Niirnberg, 1749. Routs, L. 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Descripciones de nvevos gusanos. Period. Zool. Arg., iii, pp. 106-111, and in Bol. Ac. Arg., iii, pp. 212-219. Wicxmann. Vom Giirtel des Regenwurms. Ber. Naturf. Fr., ii, 1777, pp. 231-240. Witiams, T. (1) Researches on the Structure and Homology of the Reproductive Organs of the Annelids. Phil. Trans., 1858, pp. 93-114, Pls. vi-viil. (2) Report on the British Annelida. Rep. Brit. Ass., 1851, pp. 159-272, Pls. ii—xi. Wison, E. B. (1) Origin of the Excretory System in the Earthworm. P. Ac. Philad., 1887, pp. 49, 50. (2) The Germbands of Lumbricus. Journ. Morph., i, pp. 183-192 ; one plate. (8) The Embryology of the Earthworm. Ibid., pp. 387-462, Pls. xvi-xxit. 752 OLIGOCHAETA Woopwarp, M. F. (1) Description of an Abnormal Earthworm possessing seven pairs of Ovaries. P. Z. S., 1892, pp. 184-188, PI. xiii. (2) Further Observations on Variations in the Genitalia of British Earthworms. P. Z. S., 1893, pp. 319-324. Pl. xxiv. Zacuarias, O. Die Tier- u. Pflanzenwelt des Siisswassers. LEinfiihrung in das Studium derselben. 2 vols. Leipsic, 1891. Zencer, N. Peloryctes inguilina. Bull. Soc. Nat. Mosc., xliii, Pl. i, pp. 221-236. Zerrevin, M. Ueber den Bau und die Theilungsvorginge des Ctenodrilus monostylos, nov. spec. Zettschr. wiss. Zool., XXX1x, pp. 615-652. ZSCHOKKE, F, (1) Beitrag zur Kenntniss der Fauna von Gebirgsseen. Zool. Anz., xiii, pp. 37-40. (2) Weiterer Beitrag zur Kenntniss der Fauna von Gebirgsseen. Zool. Anz., xiv, pp. 119-123, 126-129. INDEX OF GENERA AND SPECIES —_++——_ *,* The names printed in capitals and italics are synonyms or species incertae sedis. The figures in heavy type refer to the page on which the description of the species will be found. ——++—_—_- _Acanthodrilus 3, 8, 9, 30, 39, 40, 46, 53, 54, 78, 85, 92, 108, 109, III, 113, 114, 118, 119, 120, 121, 122, 123, 141, 143, 150, 151, 152, 153, 154, 161, 162, 203, 390, 454, 455; 457, 458, 459, 478, 517, 518, 519, 520, 522, 523, 524, 525, 526, 527, 549, 553, 559, 504, 583, 619, 623, 674. A. annectens 48, 67, 100, 146, 147, 521, 529, 539 532, 536, 544, 549, 683. A. antarecticus 526, 532, 553: A. aquarum dulcium 145, 528, 529, 532, 542. A. australis 529, 532, 5438. A. beddardi 563. A. bicinctus, 532, 546. A. bovei 532, 541, 542, 546. A. buttikoferi 563. / A. capensis 174, 517, 528, 529, 532, 589. A. carneus 532, 548. A. chilensis 532, 547. A. cingulatus 532, 547. A. communis 530, 532- A. dalei 528, 532, 538, 549. A. decipiens 532, 545. A. dissimilis 37, 40, 129, 131, 161, 519, 520, 523, 529, 581, 532; 535, 55°, 553- A. falclandicus 29, 131, 518, 519, 528, 529, 532, 541, 542. A. georgianus 7, 15, 145, 475, 548, 519, 529, 530, 532, 540, 541, 542, 680. A. hilgeri 532, 587. A. huttont 526, 532. A. kerguelarum 532, 539. A, kerguelenensis, 528, 539, 549. Acanthodrilus (continued). A, layardi 545. . littoralis 529, 532, 536. . macleayi 529, 532, 543. magellanicus 532, 546. . Minutus 532, 546. monocystis 110, 131, 458, 459, 532, 5385. multiporus 525, 526, 532, 551. neglectus 531. novae-zelaudiae 38, 67, 161, 516, 517, 518, 519, 520, 528, 529, 530, 532, 534, 535, 660. obtusus 161, 523, 530. occidentalis 532, 546. . paludosus 48, 100, 521, 529, 530, 532, 544. parkeri 531, 532, 584, 550. . pictus 519, 521, 529, 532, 537. . platyurus 532, 538, 548. plumbeus 532, 548. purpureus 532, 547. putablensis 532, 547. rosae 78, 127, 520, 532, 534, schlegelit 161, 562. schmardae 131, 523, 528, 532, 543. . sctoanus 564. . smithii 517, 529, 532, 535. . Spegazzinti 517, 522, 523, 524, 531, 554, 555: A. thomast 526, 532. A. ungulatus 131, 133, 161, 516, 522, 529, 532, 545. A, valdiviensis 532, 538. A. verticillatus 531, 675. ACESTUS 211, 214, 248, 249. BPRDPRDD DD DDD > ER DRA bb bbb 5D 754 ACHAETA 353. A, eisent 355. Acolosoma 2; 1 14, 15, 17, 18, 25; 34; 53, 65, 66, 73, 74, 80, 81, 84, 85, 98, 100, 103, 129, 130, 131, 141, 149, 156, 160, 162, 167, 168, 170, 171, 173, 176, 276, 277, 279, 280, 306, 311, 312, 354. Ae. aurigena 182, 185. Ae. balsamo 183. Ae. chlorostictum 182. Ae. decorum 183, 186. Ae. ehrenbergi 176, 183. Ae. headleyi 14, 77, 178, 179, 180, 182, 186. Ae. hemprichii 178, 180, 181, 182, 183, 184. Ae. italicum 184. Ae. lacteum 186. Ae. leidyi 177, 182, 185, 187. Ae. macrogaster 182. Ae. niveum 177, 182, 185, 186, 280. Ae. pictum 182. Ae. quaternarium 14, 65, 177, 178, 180, 181, 183, 184, 186. Ae. stokesiz 183. Ae. ternarium 182. Ae. tenebrarum 19, 140, 176, 177, 178, 179, 180, 181, 182, 185, 186, 187. Ae. variegatum 177, 178, 180, 181, 182, 184, 186. Ae. venustum 184. AEOLONAIS 176. Anteus 98, 103, 150, 152, 174, 624, 626, 627, 629, 631, 632, 633, 634, 635, 636, 638, 639, 641, 643, 645, 650, 651, 661, 666, 676. A, appuni 634, 635, 681. A, brunneus 634, 635, 638, 641. = A. ccllichuetus 628, 634, 635, 642. A. distinctus 641. A. gigas 126, 638, 651, 652. A. heterostichon 638, 651, 652. A. horsti, 651, 652. A. microchaetus 669. A. papillifer 628, 634, 635, 662. A, teres 662. ARGILOPHILUS 441, 495. A. marmoratus ornatus 495. A. marmoratus papillifer 495. AULOPHORUS 156, 297. A. oxycephala 297, 298. A. discocephalus 298. A, vagus 299, 300. ARCHIENCHYTRAEUS 313, 321, 330, 349. A. affinis 351. A. buchholtzit 338. A. dicksonii, 352. A. gemmatus 313. OLIGOCHAETA ARCHIENCHYTRAEUS (continued). oe lampas 313. A. levinsenit 313. A. leptodera 351. A, moebtt 315, 336. A, nasutus 323, 351. A. nervosus 323, 325. A. ochraceus 313. A. profugus 323, 326. A. tenellus 313. A. ventriculosus 350. Allolobophora 4, 28, 45, 54, 60, 92, 130, 142, 146, 149, 506, 524, 604, 623, 666, 689, 690, 691, 692, 693, 694, 698. A. alpina 698, 710. A. antipae 716. . aquatilis 715. . arborea 704. . boeckii 705. bogdanovii 720. . byblica 699, 714. caliginosa 699. carnea 715. caucasica 720. celéica 39, 702. chlorotica 3, 39, 148, 694, 699, 703, 709. complanata 39, 131, 138, 423, 680, 689, 690, 694, 699, 702, 704, 710, 712, 717. constricta 126, 666, 688, 689, 698, 711. cyanea 695, 699, 702, 712, 719. dubiosa 708, 718. elseni 666, 688, 689, 698, 705. . festae 699, 710. fitzingeri 721. foetida 32, 39, 143, 148, 688, 698, 702, 706, 710, 713, 715; A. fraisset 707. A. frivaldsykyi, 719. . georgii 699, 716. . gigas 687, 699, 701, 708. . gracilis 719. . hermanni 715. . hibernica 713. . hispanica 708. . icterica 699, 708. japonica 693, 699, 718. . Jassyensis 699, 717. . leoni 689, 699, 717. . limicola 699, 716. . lissaensis 699, 717. longa 7Ot. madeirensis 718. mamumalis, 699, 702. . mediterranea 719. . mima 699, 718. PPPP PDD DDRDPRD DDD RD PPD>D>R b> bbb >> Rb bbb INDEX OF GENERA AND SPECIES Allolobophora (continued), - minima 693, 701. - molleri 688, 692, 699, 709, WIL, - mucosa 692, 715. . nassonovii 720. neglecta 703, 704. ninnit 694. - nordenskioldii 715. norvegica 704. . octaedra 146, 699. . oerleyi 720, 721. parva 705. . patriarchalis 699, 714. . platyura 699, 720. profuga 710, 712. putra 146, 148. putris 696, 698, 707, 708. pygmaea 699, 700. rosea 698, 714. . rubida 710. . samarigera 126, 138, 698, 714. . savignyt 130, 699. . Semitica 699, 714. smaragdina 699, 703, TIL. . studiosa 693, 702, 704, 712. submontana 713. subrubicunda 707, 711, 712, 713. syriaca 698, 718. tellinii 39, 699, 709. . tenuis 70%. . . terrestris 695, 699, 701. . transpadana 39, 423, 699, 709, 712. . trapezotdes 148, 700, 709, 716, 717. . tumida 705. . turgida 39, 700. veneta 698, 706, 708, 710, 712, 718. Alluroides 125, 207, 208, 209, 210, 224, 226, 586. . : A. pordagei 225. Allurus 88, 142, 145, 146, 147, 195, 210, 623, 688, 692, 693, 695, 705. A. amphisbaena 696. A. brevicollis 696. A, brevispinus 696. A. dubius 697. A. flavus 696. A. hercynius 695, 696, 697. A. macrurus 696. A. neopolitanus 695, 697. A. ninnit 693, 695, 697. ‘A. phosphoreus 696. A. tetraedrus 39, 693, 695, 698. A. tetragonurus 696, 698. ALMA 76, A. nilotica 83, 175, 276, 302. PRPRDD>ADDDRADDL DEL DDR REED EDR EDR EDR ED 755 Alvania 59, 102, 125, 132, 151, 580, 586, 617, 619. A. millsoni 105, 621. Amphichaeta 35, 275, 279, 280, 808, 305. A. leydigi 304. A. sannio 304. AmyYnTAs 362, 388. A. aeruginosus 402, 403. Anachaeta 5, 6, 8, 11, 14, 16, 308, 309, 310, 312, 322, 343, 853, 655. A. bohemica 5, 14, 330, 354, 355. A. eiseni 6, 354, 355, 356. ANALYCUS 314, 315. A. armatus 317. 320. A. flavus 318. A. glandulosus 314, 318. ANISOCHAETA 10, 359, 369, 370. Annadrilus 34, 151, 152, 624, 664, 665, 680, 686. 4 A. quadrangulus 680. APORRECTODEA 691. A. chlorotica 703. ARCHAEODRILUS 208. ARCHAEORYCTES 259. Benhamia 41, 53, 57, 58, 129, 150, I5!, 152, 153, 357, 454, 457, 458, 506, 517, 519, 524, 525, 626, 527, 528, 554, 559, VII. : . B. affinis 560, 562, 567. B. annae 123, 860, 561, 570. B. beddardi 131, 522, 525, 529, 860, 561, 562, 563. : bolavi 518, 525, 559, 560, 561, 562, 565. . buttikoferi 525, 560, 562, 563. . buttneri 560, 562, 567. castanea 560, 561, 571. crassa 458, 529, 560, 561, 565, 570. culminis 560, 562, 572. curta, 560, 561, 572. equatorialis 560, 562, 572. floresiana 560, 561, 570. godeffroyi 560, 562, 566, 570. . gracilis 560, 562, 569. inermis 560, 562, 568. intermedia 560, 562, 564, 565. itiolensis 560, 561, 562, 567. kafuruensis 560, 562, 572. malayana 458, 560, 562, 569. mexicana 560, 562, 566, 567, 571. . monticola 560, 561, 571. . pallida 560, 562, 569. . parva 560, 561, 571. . TOSEA 522, 525, 5600, 561, 562, 563, 564. schlegelii 70, 525, 560, 562. . Scloana 525, 560, 562, 564. bd td bd bd ES bo So bd bd dd bd dd od dd dd 5D2 756 Benhamia (continued). B. stuhlmanni 529, 560, 562, 564, 567. B. tenuis 560, 562, 565. B. togoensis 516, 560, 562, 568. B. sylvestris 560, 561, 571. B. whytei 529, 560, 561, 565, 570. Bilimba 151, 153, 586, 624, 627, 664, 665, 674, 686. B. papillata 681, 686, 687. BLANONAIS 242. B. filiformis 244. Bohemilla 14, 269, 275, 276, 278, 283, 296. B. comata 7, 277, 296. Bothrioneuron 68, 70, 72, 108, 137, 228, 230, 231, 232, 235, 236, 237, 238, 239, 240, 241, 242, 268, 296. B. americanum 126, 269. B. vejdovskyanum 107, 126, 235, 236, 269. Brachydrilus 46, 120, 623, 624, 626, 627, 629, 631, 665. Branchiura 28, 29, 66, 69, 72, 76, 80, 82, 84, 108, 115, 116, 117, 175, 193, 228, 229, 230, 231, 232, 233, 236, 237, 238, 239, 240, 241, 250, 255, 263, 270, 276, 298, 302. B. sowerbii 241, 271. Bryodrilus 311, 356. B. ehlersi 356. Buchholzia 38, 61, 80, 85, 310, 311, 312, 320, 333, 349, 351. B. appendiculata 195, 330, 333, 3884, 335, 692. B. fallax 333, 334, 342. BytHonomus 208. CAECARIA 283. C. rara 283. C. silesiaca 283. C. brevirostris 283. Callidrilus 151, 153, 624, 627, 629, 664, 665, 669, 674. C. scrobifer 674, 675. CaMPTODRILUS 226, 228, 248, 250. C. californicus 251. C. corallinus 254. C. igneus 255. C. spiralis 251. Chaetobranchus 76, 175, 275, 276, 301. Ch. semperi 83, 302. CHAETODEMUS 176. Ch. multisetosus 183. Ch. panduratus 186, 187. Ch. quaternarius 184. Chaetogaster 11, 20, 21, 35, 65, 70, 81, 156, 168, 219, 275, 276, 280, 281, 303, 304. Ch. crystallinus 22. 66, 305, 807. Ch. diaphanus 22, 806, 308. Ch. diastrophus 406, 807. OLIGOCHAETA Chaetogaster (continued). Ch. filiformis 304, 305, 306, 307. Ch. furcatus 306. Ch. gulosus 306. Ch. limnaei 306, 308. Ch. mullert 307, 308. Ch. niveus 306, 307. Ch, vermicularis 306, 307. CHIRODRILUS 312, 314. C. abyssorum 314. C. larviformis 314. Claparedilla 208, 210, 212, 219. C. lankesteri 221. C. meridionalis 220. Clitellio 72, 149, 156, 207, 214, 228, 230, 231, 232, 233, 238, 244, 246, 248, 249, 260, 268, 294, 295, 296, 321. . alpestris 254. . arenarius 246, 247, 261, 268, 269, 295. . ater 246, 260, 261, 262. . benedit 247, 261. . claparedianus 251. corallinus 254. dubius 247. heterosetosus 250. hoffmeistert 252. igneus 255. inequalis 247. irroratus 247. minutus 247, 328. monticola 253. neurosoma 247. . ornatus 253. . stlvant 254. . steigerwaldi 253. C.%suchumicus 250. C. tenuis 244. C. udekemianus 252. Criodrilus 19, 25, 32, 53, 75, 82, 96, 136, 138, 146, 147, 151, 153, 156, 624, 643, 646, 665, 679, 683, 687. C. dubiosus 667, 718. C. lacuum 65, 126, 667. Cryptodrilus 41, 46, 150, 151, 152, 153, 154, 358, 444, 445, 446, 450, 451, 452, 456, 459, 468, 471, 477, 480, 481, 482, 484, 487, 496, 497, 627. C. camdenensis 498, 504. C. cameroni 498, 502. C. canaliculatus 448, 497, 498, 499. C. dubius 447, 448, 484, 498, 503. C. fasciatus 451, 481. C. fastigatus 446, 448, 483. C. fletcheri 38, 445, 450, 498, 499, 500. C. frenchi 448, 493. RAARQKHAARALRKAARARRKARAN INDEX OF Cryptodrilus (continwed). C. gippslandicus 448, 492. grandis 498, 505. . hulmei 498, 501. . tlawarra 448, 498, 503. . insignis 498, 501. . insularis 448, 471. intermedius 447, 448, 492. lucasi 448, 489. macedonensis 448, 493. . manifestus 446, 448, 498, 499. . mediocris 448, 483. minor 448, 489. mudgeanus 448, 498, 503. narrensis 448, 489. obscurus 498, 501. oxleyensis 448, 500. pelewensis 451. purpureus 451, 452, 481. pygmaeus 498, 504. rubens 447, 448, 491. . rusticus 448, 450, 498, 504. . saccarius 446, 448, 498, 502. . semicinctus 448, 494. . simulans 448, 498, 505. . singularis 446, 448, 498, 502. . sloanei 446, 448, 498, 499. . smithi 494. C. spatulifer 152, 460, 463. C. tanjilensis 448, 493. C. tenuis 448, 483. C. tryont 498, 500. C. unicus 446, 448, 451. C. victoriae 448, 488. C. victoriensis 498, 500. C. willsiensis 448, 493. Ste CTENODRILUS 15, 80, 156, 160, 170, 171, 177, 281. Deinodrilus 8, 9, 27, 28, 41, I51, 153, 154, 496, 516, 522, 523, 527, 557. D. benhami 63, 358, 557. DELTANIA 444, 459, 460, 466. D. benhami 467. D. elegans 466. D. troyert 467. DENDROBAENA 690, 691. D. boeckit 705. D. camerani 706. D. caucasica 720. D. nasonovit 720. D. rubida 706, 708. Deodrilus 4, 11, 151, 152, 166, 444, 456, 478, 480, 623, 631. D. jacksoni 444, 479. GENERA AND SPECIES mediterreus 446, 447, 448, 450, 498, 499. 757 Dero 11, 66, 76, 82, 83, 106, 156, 275, 278, 281, 297, 302, 304. . acuta 298, 299. . decapoda 298. . digitata 82, 83, 298. . furcata 297, 298, 299, 300. . intermedia 298. . latissima 298, 800. . limosa 298. - miilleri 299. . nultibranchiata 279, 297, 801. . obtusa 82, 83, 298, 299, 300. . palpigera 298, 299. . perrieri 82, 83, 278, 298, 299, 301. _ philippinensis 298, 302. D. rodriguezi 298, 299. D, stuhlmanni 298. D. vaga 297, 300. DEROSTOMA 304. D. laticeps 306. Desmogaster 38, 119, 151, 153, 193, 194,195, 196, 198, 205. D. doriae 205. D. horsti 205. Diachaeta 8, 150, 152, 622, 624, 626, 629, 630, 631, 632, 633. 646, 647, 648, 656, 659, 663. D. littoralis 133, 654, 659, 663. D. thomasii 663. D. windlet 649. Dichogaster 41, 55, 121, 151, 167, 357, 444, 456, 457, 476, 522. D. damonis 119, 121, 445. 458, 477, 523. D. hupferi 478. D. minus 477. DIDYMOGASTER 444, 450, 484. D. sylvaticus 450, 451, 484. Digaster 41, 55. 151, 153, 443, 444) 445; 459, 459, 457, 477; 484, 505. D. armifera 450, 485, 486. . excavata 406. . lumbricoides 450, 484, 485. . nemoralis 486. . perrieri 450, 485. . queenslandica 485. . sylvaticus 487. DivITrBRANCHUS niloticus 83, 175, 276, 302. Diplocardia 118, 151, 153, 358, 519, 521, 524, 526, 527, 530, 548. D. communis 100, 204, 522, 526, 529, 549. Diporochaeta 23, 46, I51, 153, 361, 369, 37%, 435, 489. D. alsophila 441. D. bakeri 440. D. barronensis 440. Sb SUSeeysyeyyds poopy 758 Diprochaeta (continued). D. copelandi 442. . dicksonia 441, . dubia 443. . intermedia 98, 369, 439. . lochensis 442. . obscura 442. . tanjilensis 442. . terrae-reginae 441. . walhallae 443. . yarraensis 441. DisT1cHOPUS 309, 312, 314, 322. D2. sylvestris 314. EcuHINnopRILUS 156. £. multispinosus 313. Eclipidrilus 85, 138, 208, 209, 211, 225. E. frigidus 226. EIsEnia 697. LE. pupa 698. Embolocephalus 228, 230, 245, 259, 272. E. plicatus 2:78. E. velutinus 207, 259, 272. EminopRILvs 645. £, equatorialis 627, 636. Eminoscolex 580, 607. E. toreutus 607. E. viridescens 607. ENCHYTRAEOIDES 329. £. marionit 329. Enchytraeus 155, 156, 162, 294, 309, 310, 313, 314, 315, 316, 321, 322, 333, 335, 341, 349, 350- . adriaticus 336, 339, 340. . affinis 336, 340, 342. . albidus 317. . appendiculatus 333, 334- . arenarius 335, 339. . argenteus 336, 340. . bisetosus 336, 344. buchholtzii 336, 338. . callosus 343. danicus 336. . dicksontt 352. durus 347. . faleiformis 317. Jenestratus 317. . fucorum 336, 337- . hegemon 348. humicultor 106, 836, 341. . hyalinus 336, 340. . juliformis 313. . latus 350. . leydignt 344, 345 . lobifer 346. . minutus 336. Hoepyyyoyy L OLIGOCHAETA Enchytraeus (contonued). Li. mirabilis 316. L. moebit 14, 101, 127, 336, 337. E. moniliformis 313. E. monochaetus 12, 168, 309, 335, 339. LE. nervosus 325. LL. pagenstechert 326, 327. LE. pellucidus 334. Li. perriert 345. E. primaevus 316. E. puteanus 353. LE. ratzeli 344. £. sepultus 313. Ei. setosus 344. . socialis 350. . sordidus 336, 337. . Spiculus 335, 336, 337. . striatus 342. . stuxbergt 336, 337. . tenuis 344. . triventralo-pectinatus 296. . vejdovskit 336, 337- . ventriculosus 350. . vermicularis LOI, 313, 336, 341, 346. ENTERION 691. £. caliginosum 699. £. castaneum 722. LL. chloroticum 703. £. cinctum 695. E. cyaneum 702. E. festivum 723. LE. firmatorum 695. E. foetidum 702. E. herculeum 724. E. ictericum 708. ELemammale 702. LE. opinum 710. E. platyurum 720, 721. LE. polyphemus 723. LE. pumilosum 722. LE. pygmaeum 700. E. roseum 414. E. rubellum 722. £. rubidum 706, 708. E. terrestre 701. E. tetraedrum 696. L. vaporartorum 695. Li. virescens 703. EPITELPHUSA 321, 322, 323. EvAxsEs 156, 175, 215. L. baicalensis 219. E. filirostris 215, 217. E. obtusirostris 214. Hudriloides 62, 79, 81, 115, 151, 480, 574, 576, 578, 580, 582, 583, 584, 585, 587, 598, 607. Seba hey INDEX OF GENERA AND SPECIES 759 Eudriloides (continued). E. brunneus 112, 575, 578, 587, 589. E. cotterilli 575, 578, 587, 589. E, durbanensis 575, 582, 587, 589. E. gypsatus 587. E. parvus 588. E. titanotus 587, 588, 589. Eudrilus 16, 38, 58, 59, 61, 71, 87, 89, 90, 91, 98, 99, 102, III, 112, 114, 116, 117, 124, 125, 132, 134, 150, 151, 155, 161, 162, 435) 457, 464, 573, 574, 575, 576, 579, 580, 582, 583, 584, 599, 600, 601, 603, 622, 627. Ef. boyert 604. E. buttneri 604, 606. E, decipiens 604, 608. E. dubius 459, 461. E. erudiens 604, 606. E. eugeniae 149, 604, 606. Fi. jullient 604, 608. E. lacaztt 604. E. pallidus 604, 605. E. peregrinus 604. E. roseus 604, 605. E, sylwicola 604, 605. EURYDAME 174. E. insignis 174. Fletcherodrilus 131, 444, 445, 451, 452, 456, 480, 579. F. unicus 481. Frederica 17, 18, 30, 143, I51, 310, 311, 312, 341, 355. F. antarctica 324, 341, 342, 347, 349. F. bisetosa 309, 336, 341, 342, 344. F. bulbosa 309, 341, 348, F. callosa 342, 348, 348. F. dura 342, 347. F. galba 308, 342, 346, 349. F. hegemon 342, 348. F leptodera 61. F. leydigi 342, 344. F. lobifera 342, 346. F, novae-zelandiae 324. F. perrieri 342, 345. F. ratzeli 342, 347, 348, 349. F, striata 341, 342, 354. GEopRILUS 548. G. singularis 548, 549, 55°. GEOGENIA 624, 636, 638, 648. G. natalensis 636. G. paradoxa 639. GEOPHAGUS 675, 677. GEoRYCTES 187, 188. G. lichtensteinit 189. G. menket 189. Geoscolex 150, 174, 480, 586, 624, 626, 627, 628, 629, 631, 632, 633, 638, 643, 652. G. forguesi 633, 643, 644. G. maximus 126, 648, 645. Glyphidrilus 34, 151, 152, 624, 626, 624, 664, 665, 679. G. weberi 98, 679. Gordiodrilus 37, 38, 46, 57, 58, 61, 62, 97, 105, I10, 116, 119, 150, 151, 152, 153, 158, 444, 453, 454, 455, 456, 506, 510, 5IL, 517) 521, 523, 574, 585, 591. . ditheca 454, 507, 509, 510. . dominicensis 506, 507, 509. . elegans 453, 507, 508. . matthewst 453. . robustus 454, 507, 508, 510. . tenuis 454, 507. . zanzibaricus 507, 509. Hatopritvs littoralis 312. Hapbotaxis 187, 188. H. menkeanus 189. HEGESIPYLE 527, 528. Hf. hanno 174, 528. Heliodrilus 16, 28, 55, 58, 59, 89, 99, III, 120, 128, 131, 151, 157, 575, 576, 577; 578, 581, 583. 584, 586, 618. H. lagosensis 619. HELopritus 156. fT. oculatus 174. Hemitubifox 230, 231, 232, 235, 243, 245, . 247, 260, 262, 264, 265, 270. HI, ater 261, 266. H. benedii 247, 260, 261, 262, 296. H. insignis 237, 238, 261, 266. Henlea 310, 312, 315, 849. H. dicksonii 350, 351, 352. H. leptodera 350, 351. LH, nasuta 350, 351, 352- H. puteana 308, 349, 853. H. socialis 350. H. ventriculosa 61, 850. Hesperodrilus 175, 227, 228, 230, 231, 232, 233, 237, 238, 255. H. albus 12, 255,256. H. branchiatus 76, 84, 237, 241, 256, 257, 270, 276, 302. H. niger 255, 257. H. pellucidus 255, 256. Heterochaeta 6, 156, 228, 230, 257. H. costata 258, 271. Hormogaster 19, 20, 151, 153, 624, 625, 626, 627, 629, 665, 681, 690. H. redii 682. Hyperiodrilus 16, 28, 55, 59, 89, 99, 125, 126, MR RARNMRAN 760 Hyperiodrilus (continue). 151, 195, 457, 579, 580, 581, 586, 607, 617, 620. H. africanus 618. HypoGaEon 156, 651, 653. HI. atys 175. LZ. heterostichon 652. ET, hirtum 175. LH. orthostichon 496. Tlyodrilus 20, 74, 82, 91, 108, 148, 206, 211, 227, 228, 230, 231, 232, 233, 236, 237, 238, 239, 240, 241, 242, 245, 263, 264, 270. I. coccineus 7, 107, 233, 236, 266. I. fragilis 261, 265, 266. I. perriert 261, 265, 266. I. sodalis 237, 243, 264, 265, 266. Tlyogenia 57, 151, 153, 622, 624, 627, 629, 630, 631, 632, 634, 649. I. africana 650. Kerria 57, 109, 115, 150, 152, 454, 455, 517, 521, 522, 523, 524, 527, 553. K. halophila 554, 556. K. macdonaldi 554, 556. K. spegazzinii 521, 555, 626. K. zonalis 554, 557. Kynotus 11, 115, 120, 130, 153, 586, 624, 627, 628, 629, 635, 636, 637. 648, 664, 665, 666, 668, 669, 674, 675, 679. K. Kelleri 677, 678. K. longus 677. K. madagascariensis 586, 676, 677, 678, 67 K. te pelea 113, 119, 130, 586, 628, om 677, 678, 688, 690. Lampiro 362, 388. L. mauritit 369: Libyodrilus 28, 44, 45, 48, 54, 71, 88, 102, 112, 134, 151, 574, 575, 577, 579 580, 582, 583, 585, 591, 593, 600, 623. L. violaceus 596; 600, 602. Limnodrilus 6 » 7, 72, 74, 75, 137, 156, 190, 206, 207, 228, 229, 230, 231, 232, 233, 234, 235: 240, 241, 242, 243, 246, 248, 263, 270. . alpestris 250, 254. . bogdanovit 251. californicus 250. claparedianus 242, 249, 251. . corallinus 250, 254. . hoffmeisteri 74, 82, 233, 249, 252, 253, 254. igneus 250, 255. monticola 250, 253. . novae-zelandiae 247. 264, 265, NEE Ee ee 574, 575, 576, 577, 578, OLIGOCHAETA Limnodrilus (continued), L. ornatus 250, 2538. L. silvani 250, 254. L. spiralis 250. L. steigerwaldi 250, 253. L. udekemianus 233, 234, 249, 252. LuMBRICOIDEA 691. Lumbriculus 15, 18, 22, 78, 85, 155, 156, Ig1, 206, 208, 209, 210, 211, 219, 2447, 248, 249, 257, 321. L. hyalinus 214. L, lacustris 214. L. lankestert 221. L. limosus 214. L. spiralis 214. L. teres, 214. L. variegatus 211, 212, 214, 220. Lophochaeta 7, 23, 70, 72, 106, 228, 230, 231, 232, 234, 236, 237, 240, 241, 269, 274. L. ignota 7, 270. Lumbricus 2, 3, 4, 8, 12, 13, 14, 15, 17, 18, 19, 22, 24, 32, 33, 35, 36, 37, 38, 39, 43, 45, 49, 59, 51, 52, 53) 55» 59, 60, 67, 69, 71, 73, 75, 86, 87, 88, 89, 90, 92, 95, 96, 97, 98, 99, 100, IOI, 103, 105, 131, I4!, 146, 149, 150, 151, 153, 155, 156, 162, 169, 170, 172, I74, 192, 211, 242, 246, 321, 325, 399, 459, 468, 506, 524, 527, 577, 604, 623, 630, 652, 653, 666, 667, 670,.689, 690, 691, 692, 693, 694, 704, 721 L. agilis 696, 697. LL, agricola 701, 724. L. alyattes 695. L. americanus 694. L. anatomicus 703. LP annularis 702. . apit 174. . aquatilis 715. . arboreus 707. . arenarius 247. . armatus 695. . blainvilleus 694. . boeckit 706. . brevispinus 703. . caeruleus 695. . caliginosus 700. . capensis 174. . castaneus 695, 721, 722. . chloroticus 703. . clitellinus 695. . communis 700, 715. . complanatus 704. . corethrurus 653, 658. . cyaneus 702. . dubtus 694. SR EERE RR INDEX OF GENERA AND SPECIES 761 Lumbricus (continued). L. eiseni 126, 705, L. ephippium 695. L. eugeniae 605. L. festivus 721, 728. L. foetidus 703. L. giganteus 695. . gigas 7OL. . glacialis 313, 694. . guildingt 174. helenae 174. herculeus 39, 701, 709, 721, 724. hirsutus 290. . hortensiae 174. . infelix 695. isidorus 694. . jordant 313. . josephinae 698. . juliformis 174. herguelarum 528, 539, 540. lineatus 244, 328. . littoralis 247, 469. . lividus 695. . luteus 695. mammalis 702. melibaeus 721, 722. michrochaetus 669. minor 695. minutus 328. . mollis 694. . Mucusus 715. . multispinosus 313. . nordenskioldi 715. . norvegicus 704. novae-hollandiae 697, 700. olidus 703, 706. omilurus 695. . pampicola 174. . papillosus 721, 722, 723. parvus 705. phosphoreus 472. polyphemus 721, 723. pupa 697. purpureus 39, 722. purus 100. . puter 705, 707, 708. putredinis 313. . pygmaeus 700, 7OI. ripartus 703. roseus 698, 714. rubescens 723. . rubidus 706. . rubrofaciatus 174. . stagnalis 694, 712. SSS EES SSS SS SES SE SESS SSS SE SSNS SSS ER rubellus 32, 39, 146, 147, 678, 721, 722. Lumbricus (continued). . subrubicundus 707. . tahitanus 174. . tellus 17 4.- . tenuis 707. . teres 694, 702. . terrestris 7O1, 702, 710, 712, 719, 720, 724. . tetraedrus 696. . trapezoides 699. tubicola 244. L. tubifes 244, 694. . turgidus 750. tyrtaeus 721, 722. valdiviensis 695. . victoris 694. . vinett 174. . viridis 703. . wanthurus 695. LycopriLvus 208, 215. L. dybowskit 215. MANDANE 527, 528. M. bovet 542. M. hilgert 537. M. littoralis 536. M. patagonica 536. M., picta 537. M. stagnalis 528, 531, 555. Marionia 311, 322, 329. M. crassa 329, 331, 332. M. ebudensis 327, 329, 331. M. enchytraeoides 329. M. georgiana 329, 332. M. semifusca 329, 381. M. sphagnetorum 34, 329, 330, 692. Megachaeta 151, 508, 576, 580, 582, 591. M. alba 27, 591, 592. E. tenuis 582, 591, 592. Megascolex 8, 9,10, 11, 41, 45, 55, 67, 71, 74, 76, 82, 85, 123, 143, 151, 152, 153, 154, 156, 161, 162, 163, 164, 359, 360, 361, 363, 365, 368, 369, 370, 435, 440, 457; 520. M. affinis 424. M. albidus 387. M. annulatus 426. M. antarcticus 369, 370. M. armatus 42, 152, 365, 370, 371, 372, 384, 385. M. aspergillum 430. M. attenuata 360, 372, 381. M. australis 371, 372, 874, 376. M. austrinus 372, 373, 375, 877. M. biserialis 430. M. brachycyclus 382. M. canaliculatus 371, 875, 441. SANNA SN SSNS 762 Megascolex (continued). M. capensis 421. M. ceylonicus 368, 370, 372, 885. M. cingulatus 372, 8382, 383. M. coeruleus 43, 58, 64, 67, 68, 69, 75, 76, 146, 148, 358, 361, 364, 360, 372, 383, 386. M. coxii 372, 381. M. dendyi 370, 372, 880. M. diffringens 402, 427. dorsalis 146, 372, 376. elongatus 431. .enormis 360, 372, 881. . excavata 5306. . exiguus 372, 373. . fecundus 372, 375. . fielderi 372, 379. . frenchi 372, 379. . frosti 372, 380. . goonmurk 372, 378. . gracilis 877. . hallii 872. . hamiltoni 372, 373. . hasselti 426. . hoggii 372, 879. . indicus 427. . indissimilis 371, 372, 876. . iris 371, 3838. . lateralis 372, 880. u. leucocyclus 386. M., lineatus 369. M. macleayi 372, 376. M. macquariensis 372, 378. M. madagascariensis 372, 385. M. margaritaceus 371, 383. M. monticola 372, 874. M. moseleyi 386. M. musicus 425. M. newcombei 118, 372, 378. M. perrieri 369. M. pictus 371, 372, 884. M. quadragenarius 431. M. raymondianus 372, 373. M. robustus 430. M. ruber 372, 379. M. sanctae-helenae 402, 403. M. sieboldi 420. M. steeli 372, 379. M. stirlingi 371, 373. M. sumatranus 422. M. sylvaticus 372, 378. M. sylvestris 369, 370, 522. M. templetonianus 3806. M. tenax 372, 377. M. wilsonianus 372, 375. eRe SARS SEES SRE ee -Mesenchytraeus 77, 93, OLIGOCHAETA Megascolides 20, 21, 27, 41, 42, 43) 44, 45; 46, 51, 151, 153, 380, 444, 445, 446, 447, 450, 452, 456, 477, 482, 486, 497. M. attenuatus 448, 488, 491. M. australis 2, 20, 41, 48, 51, 146, 358, 447, 450, 451, 488, 495. MM. camdenensis 448. M. cameront 448, 502. M. frenchi 488, 493. M. gippslandicus 447, 448, 450, 488, 492. M. grandis 448. M. hulmei 448, 501. M. illawarrae 446, 448, 503. M. incertus 447, 448, 488, 490. M. insignis 448, 501. . intermedius 488, 492. . lucasi 488, 489. . macedonensis 488, 493. . manni, 448, 488, 490. . minor 488, 489. . narrensis 488, 489. . obscurus 448, 501.. . ornatus 488, 495. orthostichon 11, 488, 498. papillifer 488, 495. . perrieri 488, 496. - pygmaeus 448, 504. . roseus 448, 488, 491. rubens 488, 491. semicinctus 488, 494. . sinuosus 447, 448, 488, 490. . smithi 488, 494. . tanjilensis 488, 493. . tasmanianus 448, 450, 488, 492. . tuberculatus 447, 448, 488, 494. M. victoriae 488. M. victoriensis 448, 500. M. willsiensis 488, 493. PERS RRERRR SER KE PRESS 95, 168, 310, 311, 312, 314. M. armatus 316, 319, 320. M. beumeri 77, 127, 317, 318. M. falciformis 77, 317. M. fenestratus 317. M. flavidus 77, 319. M. flavus 318. M. mirabilis 77, 316. M. primaevus 77, 316. M. setosus 309, 316, 319. Mrsopacuys 156. Metadrilus 151, 580, 582, 592. M. rukajurdi 594. Microchaeta 14, 37, 38, 67, 68, 130, I51, 153, 624, 626, 628, 629, 631, 635, 637, 640, 664, 665, 667, 674, 677, 682. INDEX OF GENERA AND SPECIES 763 Microchaeta (continued). M. beddardi 668, 669, 672, 673. M, belli 664, 669, 673. M. benhami 120, 665, 668, 669, 678. M. microchaeta 670. M. papillata 664, 668, 669, 672. M. rappi 2, 668, 669, 672, 673, 711. Microdrilus 53, 61, 140, 151, 152, 357, 444, 456, 458, 459, 477, 484, 505, 561. M. saliens 458, 459, 506. Microscolex 46, 55, 116, 140, 150, 151, 152, 444, 455, 456, 457, 459. . algeriensis 460, 462. . benhami 461, 467. . corralensis 461, 465. . diversicolor 461, 466. dubius 460, 461. elegans 461, 466. gracilis 461, 465. griseus 461, 464. . longiseta 461, 466. michaelseni 461, 464. minutus 460, 463. modestus 161, 459, 460, 461, 523. monticola 461, 467. . novae-zelandiae 110, 460, 463. . papillosus 461, 465, 466. . poultoni 460, 462. . robustus 461, 464. . spatulifer 460, 463. . troyeri 461, 467. Millsonia 64, 153, 444, 445, 456, 459, 479. M. nigra 480. M. rubens 450. Moniligaster 14, 55, 57, 82, 88, 93, Ioo, 114, I15, I17, 118, I1g, 121, 125, 140, 150, I51I, 152, 158, 159, 161, 164, 192, 193, 194, 195, 196, 205, 575, 668, 683. M. bahamensis 133, 140, 194, 196, 197, 198, 199, 202, 203. M., barwelli 197, 198, 199, 200, 202, 203. M. beddardi 197, 198, 200. M. deshayesi 192, 196, 198, 199, 200, M. grandis 192, 198. M. houteni 194, 195, 196, 197, 198, 199, 201, 203, 204. M. indicus 133, 196, 197, 198, 199, 200, 202, 204. M. japonicus 198, 199, 201. . minutus 198, 199. . papillatus 198. . robustus 198. . ruber 198, 199. . sapphirinaoides 198. . uniquus 198. SEP Eee ee eee eee eee SSS5EE Moniligaster (continued). M. viridis 194, 196, 197, 199, 200, 201, 202, 203. MonopyLePHoRus 20, 23, 268, 271. M. rubroniveus 268, 269, 296. Mvcipa 691. Moraia 304. M. heterodactyla 306. Naripina uwmbellifera 260. Naipium 278, 289, 290, 302. NV. breviceps 290. NV. lutewm 278, 292. Nais 155, 156, 242, 262, 275, 278, 281, 280, + 293; a 295, 296, 297, 304, 306, 307, 321. N, albida 313. . appendiculata 282, 287. . auricularis 298. . barbata 278, 280, 282, 283. NV. bipunctata 283. . caecilia 292 ‘ . carolina 283. . caudata 298. . clavicornis 283. NV. diaphana 306. NV, diastropha 30%. N. elinquis 7, 65, 106, 276, 277, 278, 279, 282, 283, 284, 288. NV. escherosa 287. N. filiformis 136, 244. NV. fusca 282, 288. NV. gigantea 250. N. gracilis 282, 286. NV. greeffi 284. NV. hamata 296. N. heterochaeta 277, 278, 282, 288, 295. N. josinae 277, 282, 285, 286, 288, 289, 295. N. lacustris 3, 277, 278, 279, 280, 282, 284, 293, 306, 307. N, littoralis 295, 328. N. lurida 282, 287. N. papillosa 259, 263. NV. parasitica 293. N, picta 283. NV. proboscidea 3, 216, 284. N. pustulosa 261. N. quadricuspidatu 283. N. reckei 282, 289. NV. rivulosa 284. NV. sanguinea 244, 252. N. scotica 283. 288, 306, 307. N. serpentina 136, 279, 282, 285. NV, ternaria 290. NY, tubifew 244. N, uncinata 296. NV. vermicularis 286, 306. Zea! z2zez 5 2 764 Nannodrilus 153, 444, 453, 454, 456, 515, 523. N. africanus 453, 516. Nemertodrilus to, 111, 112, 134, 151, 577, 580, 582, 583, 595, 597, 598. N. griseus 600. NEMODRILUS 156, 187, 188. NV. filiformis 189. NEODRILUS 522, 523. N, monocystis 518, 535. NEOENCHYTRAEUS 314, 315, 335, 344- NV. bisetosus 344. N. bulbosus 343. NV. callosus 343. NV. durus 347. NV, fenestratus 315, 317. NV. galba 346. LV. hyalinus 316, 340. NV, leydigtt 344. NV. perriert 345. NV. ratzeli 347. NV. stuxbergi 336. N. vejdovskyi 318, 336. NEREIS lacustris 155, 284. Nirocris 362, 388. NV. gracilis 402. Notocama 6091. NOTOSCOLEX 444, 445, 446. XM. camdenensis 504. NV. gippslandicus 495. NV. grandis 505. NV. tasmanianus 492. NV. tuberculosus 494. Notykus 151, 580, 582, 585, 587, 590, 594. N. emini 575, 590, 595. Ocnerodrilus 11, 38, 46, 57, 58, 59, 63, 75; 97, 109, T15, 150, 151, 164, 444, 453, 454, 455, 456, 458, 506, 507, 510, 521, 523, 524, 561, 650. . affinis 515. . agricola 511, 514. . beddardi 512. bukobensis 514. contractus 511, 514. . elseni 453, 511, 512. guatemalae 512. . hendriei 512. lacuum 511, 515. . limicola 510, 511, 512. . occidentalis 511, 512. . quilimanensis 514. . rosae 511, 512. . sonorae 512, Octochaetus 27, 33, 41, 42, 43, 48, 40, 52, 535 63, 86, 103, 105, 115, 151, 153, 162, 169, Ssoocnocooooooo OLIGOCHAETA Octochaetus (continued). I7I, 172, 516, 517, 518, 519, 520, 521, 526, 527, 529, 530, 550, 619, 623. O. antarcticus 122, 517, 520, 550, 551, 553. O. huttoni 519, 520, 550, 551, 552. O. multiporus 33, 41, 47, 48, 49, 51, 55, 60, 64, 67; 104, 122, 128, 146, 147, 148, 160, 162, 393, 517; 519, 520, 546, 550, 551, 554, 638. O. thomasi 520, 521, 550, 552. OCTOLASION 691. O. boeckit 706. O. frivaldszkyi 719. O. gracile 719. O. lactewm 712. O. minimum 4ot. O. platyurum 720, 721. O. profugum 712. O. rubidum 719. O. subrubicundum 707. O. transpadarum 409. Onychochaeta 6, 10,15, 55, 150, 152, 623, 624, 626, 627, 629, 630, 631, 632, 633, 634, 635, 648, 654, 656. O. windlei 7, 649. OPHIDONAIS 281, 294. O. reckei 289. O. serpentina 285, 286. O. uncinata 296. O. vermicularis 285, 286. Opsonals 281. O. elinguis 284. O. obtusa 283. Pachydrilus ror, 156, 168, 194, 247, 309, 310, 311, 312, 314, 821, 329, 340, 349, 350, 353- affints 325. bewmert 315, 318. catanensis 324. cavicola 325. charkoviensis 325. CYASSUS 324, 332. ebudensis 331. flavus 318. fossarum 324. georgianus 332. germanicus 323, 328, 329. gracilis 325. krohnit 324, 325. lacteus 322, 336, 337. lacustris 325. limosus 327. lineatus 323, 324, 325, 828. litoreus 325, 829. maxlMUs 323, 324, 325, 327. RUD hahah INDEX OF GENERA AND SPECIES Pachydrilus (continued). P. minutus 309, 324, 325, 328. P. nervosus 323, 324, 825, 328, 337. P. opacus 325. P. pagenstecheri 309, 323, 324, 325, 326, 827. P. profugus 324, 325, 326. P. proximus 325. P. rivalis 328. P. semifuscus 331, 341. P. similis 325. P. sphagnetorum 322, 330. P. subterraneus 324, 325, 327, 328. P. verrucosus 324, 325, 326, 331. Paradrilus 127, 578, 579, 580, 581, 615. P. purpureus 615, 616. P. rosae 573, 615, 616. P. ruber 615, 616. PaRANAIS 294. P. littoralis 295, 296. P. uncinata 296. Parenchytraeus 311, 314, 357. P. litteratus 357. Pareudrilis 112, 134, 151, 574, 580, 582, 583, 595, 596, 599. P. stagnalis 596. Pelodrilus 14, 18, 85, 108, 143, 145, 158, 191. P. violaceus 192. PELORYCTES 246, 260. P. arenarius 247. P. inquilina 261, 296. Peloscolex 228, 232, 258. P. variegatus 258. Perichaeta I, 8, 9, 10, 11, 23, 41, 43, 44. 45, 52, 54, 55, 56, 63, 64, 71, 75, 78. 79, 82, 85, 86, 97, 98, IOI, 104, I0g, TIO, 113, II4, I15, I19, 123, 129, 130, 131, 141, 142, 143, 148, 149, 150, 151, 153, 154, 156, 161, 162, 164, 166, 169, I71, 172, 237, 240, 358, 360, 361, 362, 363, 364, 388, 434, 435, 439, 457, 480, 481, 491, 506, 518, 520, 522, 524, 549, 558, 628, 633, 634, 635, 642, 655, 661, 689. acystis 126, 369, 391, 393, 398, 423, 430. aeliana 395, 398, 405. affinis 149, 424. albida 387. alsophila 367, 441. annulata 394, 398, 426. armata 384. P. aspergillum 144, 395, 400, 410, 480. P. attenuata 364, 367, 381. , P. australis 366, 374. P. austrina 366, 377. P. bakeri 364, 365, 366. 440. de by 0 765 Perichaeta (continued). P. barbadensis 391, 393, 394, 395, 397, 400, 412, 415. P. barronensis 365, 366, 440. P. bermudensis 43, 44, 144, 391, 395) 397) 400, 410, 430, P. bicincta 392, 402. birmanica 395, 398, 405. biserialis 391, 400, 423, 430. . bivaginata 341. bosschae 398, 432. bournei 395, 398, 403. . brachycycla 382. burlariensis 403. campanulata 424, 425. canaliculata 364, 366, 375. capensis 393, 395, 397, 400, 421, 432. carinensis 395, 398, 404. ceylonica. 110, I1g9, 121, 168, 385. . cingulata 382. . coerulea 369, 384. . copelandi 3647, 442. corticis 369, 370. coxtt 364, 367, 381. darnleiensis 364, 367, 394, 396, 397, 400, 406, 416. dendyt 365, 367, 368, 380. dicksonia 367, 441. dicystis 402. diffringens 427. divergens 390, 396, 400, 414, 417. dorsalis 366, 376. dubia 367, 395, 400, 443. dyeri 29, 388, 391, 396, 397, 400, 411. elongata 394, 397, 400, 481. enganensis 396, 398, 404, 422. enormis 364, 367, 381. everetti 168, 389, 397, 419, 428. P. exigua 366, 373. P. falcata 400, 481. P. fasciata 394, 398, 405. P. feae 388, 396, 398, 404. P. fecunda 366, 368, 375. P. ferdinandi 390, 393, 394; 398, 418. P. fieldert 367, 379- P. forbesi 143, 395, 398 423. P. frenchii 367, 379. P. frosti 367, 380. P. goonmurk 367, 378. P. gracilis 366, 371, 377: P. grubei 394, 397, 398, 417. P. hallii 367. P. hamiltont 366, 373. P. hasselti 97, 394, 398, 426. P. hawayana 395, 397, 398, 420. TNS Dh yh hy 766 OLIGOCHAETA Perichaeta (continued). P. hesperidum 114, 394, 397, 400, 415. P. heterochaeta 42%. P. hilgendorfi 144, 171, 389, 394, 397, 398, 409. P. hoggtt 367, 379. P. horsti 434. P. houlleti 78, 124, 133, 144, 149, 359, 360, 384, 391, 392, 393, 395, 397; 400, 424. P. hulikalensis 371. P. ijima 359, 393, 395) 398, 414. P. indica 11, 29, 114, 144, 149, 388, 391, 396, 397, 398, 402, 427. P. indissimilis 367, 376. P. inflata 400, 433. P. intermedia 364, 365, 439. P. japonica 394, 398, 413, 426. P. juliana 402. P. kinabaluensis 168, 389, 429. . lateralis 367, 380. . lawsoni 371. . leucocycla 363, 369, 386. . lochensis 367, 442. longa 385, 395, 398, 409. . luzonica 369, 384. . macleayt 366, 376. macquariensis 366, 378, . madagascariensis 152, 385. . malamaniensts 44. mandhorensis 395, 398, 418. . martensi 396, 400, 414, 416. . masatakae III, 395, 400, 414, 417. . Iauritiana 369, 394, 400, 415. . Minima 388, 394, 400, 414. . modigliani 396, 398, 405. . monilicystis 410. . monticola 366, 374. . morrisi 388, 394, 400, 411. . musica 359, 388, 389, 394, 398, 409, 425. neoguinensis 389, 396, 398, 416. . newcombet 378. . hipponica 394, 396, 397, 400, 418. . novae-zelandiae 364. . novarae 395, 397, 398, 417. . obscura 364, 442. . operculata 421. . pallida 397, 400, 415. . papillata 168, 428, 429. parva 398, 433. peguana 395, 398, 403. . pentacystis 390, 396, 398, 422 peregrina 364, 367, 396, 397, 400, 406. philippina 395, 398, 421. . posthuma 41, 144, 396, 397, 400, 424. . pulchra 394, 398, 408. WHT TROND Perichaeta (continued). P. pusilla 398, 433. P. P. P P P. P. P P iB P P. P P P P. P P P P BP fi P P P B P P quadragenaria 394, 400, 481. queenslandica 364, 366, 390, 395, 397, 400, 407. . racemosa 394, 398, 420. . raymondiana 366, 373. ringeana 390, 393, 395, 397, 398, 419. robusta 41, 395, 400, 480. . rodericensis 402. . rokugo 389, 409. . rubra 367, 379. . salettensis 371. . sangirensis 130, 389, 394, 398, 418. . sarawacensis 168, 389, 429. . schmardae 394, 413. . sleboldi 64, 389, 395, 398, 413, 420. sinensis 360, 388, 391, 396, 400, 410. . sluiteri 395, 400, 407. . steelid 367, 379. . stelleri 168, 389, 393, 397, 398, 419, 428. . stirling? 366, 373. . stuarti 368, 522. . subguadrangula 402, 428. . sumatrana 358, 395, 398, 422. . sylvatica 367, 378. . tattensis 4177. . tanjilensis 367, 442. . taprobanae 10, 110, 360, 388, 390, 391, 394, 397, 400, 41], 416. . tenax, 366, 377. P. tenkatei 400, 482. P . terrae-reginae 364, 366, 441. P. tijibodae 398, 482. P. P P P. tokioensis 394, 400, 418. . tmicystis 402. . udekemt 144, 393, 395, 398, 425. upoluensis 360, 392, 395, 397, 400, 402, 429. P. urceolata 398, 432. P. vaillanti 396, 398, 421, 422. P. variabilis 400, 481. P. violacea 388, 396, 398, 407, 415, 423. P. viridis 388, 402. P. vitiensis 390, 394, 397, 398, 407, 427. P. vordermanni 380, 396, 400, 403. P. wathallae 367, 443. P P . wilsoniana 366, 375. . yarraensis 367, 369, 441. Perionyx 46, 123, 151, 152, 153, 362, 363, 370, 381, 485, 623. P. arboricola 436, 488. P. excavatus 142, 485, 696. P. gruenewaldi 436, 487. P. intermedius 436, 487. INDEX OF GENERA AND SPECIES Perionyx (continued). P. macintoshii 436, 438. P. saltans 436, 438. P, sansibaricus 152, 436, 438. P. violaceus 436, 437. PERISSOGASTER 55, 151, 444, 450, 451, 484. P. excavata 450, 486. P. nemoralis 450, 486. P. queenslandica 450, 485. PERRIERA 363, 388. PHERETIMA 362, 388. P. californica 369. P. montana 369. PHOTODRILUS 444, 455, 456, 468. P. phosphoreus 472. Phreatothrix 85, 208, 210, 217, 218, 222, 256, 277; 327- P. pragensis 219. Phreodrilus 7, 14, 22, 23, 66, 68, 69, 72, 77, 78, 80, 85, 95, 99, 102, 132, 167, 207, 2247, 228, 232, 255, 273. P. subterraneus 175. Phreoryctes 3, 7, 12, 18, 19, 22, 65, 66, 85, 86, QI, 100, 102, 156, 157, 158, 168, 171. 172, 173, 187, I9I, 194, 323. P. emissarius 189, 190. P. filiformis 189. P. heydeni 189. P. menkeanus 189, Igo. P. smithii 140, 172, 188, 190, 191. Plagiochaeta 41, 64, 151, 153, 154, 165, 359, 365, 451, 484, 516, 519, 522, 523, 327, 558, 559. P. punctata 558. Platydrilus 574, 576, 580, 582, 584, 597. P. callichaeta 597. P. lewaensis 576, 587, 597, 598. P. megachaeta 598. Pleionogaster 8, 55, 151, 153, 194, 368, 433, 457, 586. P. horsti 359, 365, 484, 435. P. jagori 365, 434. P. samariensis 365, 434. PLEUROCHAETA 363. P. moseleyt 386. PLEUROPHLEBS 182. PLUTELLUS 34, 86, 103, 151, 153, 435, 443; 444, 445, 452, 486. P. heteroporus 452, 487. P. perriert 452, 487, 496. Popopritus 246, 248, 249. Polytoreutus 26, 58, 60, 88, 93, 136, 138, IAI, 573, 579, 580, 581, 585, 586, 593, 608, 615, 623, 666.- P. coeruleus 60, 582, 608, 609, 611. 767 Polytoreutus (continued). P. finni 586, 608, 611. . gregorianus 612. . kilindinensis 576, 608, 611. . magilensis 608, 609, 610. . sylvestris 608, 6138. . usindjaensis 613. . Violaceus 575, 608, 609, 610, 612. Pontodrilus 20, 22, 23, 34, 46, 110, 114, 116, I17, 149, 150, 151, 158, 240, 435, 443, 444, 455, 450, 462, 468, 627, 644, 654, 659, 696. P. arenae 469, 470, 479. P. bermudensis 55, 444, 468, 469, 6509. P. hesperidum 468, 471. P. insularis 468, 4:71. P. littoralis 468, 469, 470. P. marionis 469. P. phosphoreus 468, 472. Pontoscolex 4, 6, 7.14, 15, 16, 20, 22, 38, 48, 55) 58, 59, 60, 61, 67, 71, 76, 77, 120, 150, I5I, 156, 166, 279, 361, 468, 519, 520, 624, 626, 627, 629, 630, 631, 632, 633, 634, 635, 637, 643, 645, 646, 647, 648, 649, 653, 661, 663, 664, 681. P. arenicola 469, 653, 656, 659, 663, 664. P. corethrurus 48, 64, 141, 149, 164, 646, 647, 656, 658, 660, 661. P. hawaiensis 658, 660. P. trinitatis 646, 647. Preussia 580, 581, 582, 614. P. lundaensis 582, 615. P. siphonochaeta 582, 614. Pristina 275, 283, 289, 302. P. breviceps 290. P, breviseta 277, 290, 292. P. equiseta 72, 277, 290, 291, 305. P. flagellum 298. P. inequalis 290. P. longiseta 278, 290. P. lutea 290, 292. P. proboscidea 290, 293. PRISTINAIS 209. P. longiseta 291. PRONAIDITES 9. Proto 297. PSAMMOBIUS 246. Psammoryctes 6, 108, 136, 228, 230, 231, 235, 238, 240, 243, 259, 261, 262. P. barbatus 11, 34, 132, 237, 260. P. batillifer 260. P. remifer 260. P. umbellifer 245, 260. PsEUDOLUMBRICULUS 208, 212, 219. P. claparedianus 210. mht ty 768 PTEROSTYLARIDES 293. P. macrochaeta 294. P. parasitica 293. PYGMAEODRILUS 46, 57, 151, 153, 453, 500, 510, 52i. P, affinis 515. P. bukobensis 514. P, lacuum 515. P. quilimanensis 514. Reithrodrilus 573, 580, 582, 590. R, minutus 166, 573, 590. Rhinodrilus 3, 150, 152, 174, 624, 626, 627, 629, 631, 632, 633, 634, 635, 636, 646, 651. Rh. brunneus 638, 641. Rh. callichaetus 642. Rh. distinctus 641. Rh. ecuadoriensis 38, 48, 66, 637, 638, 639, 640, 641. Rh. gulielmi 3, 37, 141, 636, 637, 638, 639, 640, 641. Rh. parodoxus 3, 637, 689, 641. Rh. proboscideus 102, 159, 642, 645. Rh. tenkatei 635, 637, 639. RHODODRILUS 444, 459, 460. A. minutus 463. Ruovoris 302, 388. R. javanica 402, 403. Rhynchelmis 15,18, 22, 23, 24, 29, 30, 32, 33, 34, 5°, 53, 69, 74, 75, 85, 87, 88, 89, 90, 93, 94 95) 115, 117, 127, 128, 133, 145, 146, 147, 148, 156, 162, 175, 208, 210, 215, 223, 636. « R. limosella 217. R. obtusirostris 217. Ripistes 281, 293. R. macrochaeta 293, 294. R. parasitica 293. SAENURIS 156, 211, 242, 314, 321. S. abyssicola 250, 313. S. barbata 260. S. canadensis 26%. S. diversisetosa 244. S. limicola 251, 513. S. lineata 328. S. peculiaris 244. S. taurica 244. S. tubifex 244. S. umbellifera 260. S. vagans 251, 313. S. variegata 244. S. velutina 259, 263, 272. SERPENTINA 156, 281. S. quadristriata 285. Siphonogaster 125, 126, 139, 151, 153, 175, OLIGOCHAETA Siphonogaster (continued). 586, 624, 628, 629, 643, 664, 665, 666, 675, 681, 682. 8. aegyptiacus 684. S. emint 684. S. millsoni 100, 126, 684, 685, 686. 8. stuhlmanni 684, 686. SLAVINA [5, 272, 281. S. appendiculata 287. S. gracilis 286. S. lurida 287. S. serpentina 285. Sparganophilus 34, 53, 71, 74, 100, 146, 147, I51, 153, 624, 627, 645, 667. S. tamesis 646. Spirosperma 6, 20, 228, 230, 231, 232, 234, 235, 240, 262, 272. S. ferow 7, 242, 249, 259, 263. 8. papillosus 263. Stercutus 74, 77, 310, 320. 8. niveus 320. STREPHURIS 242. S. agilis 244. Stuhlmannia 62, 79, 88, 125, 126, 151, 574, 580, 582, 583, 584, 585, 595, 602, 613, 615, 6147, 622. 8. variabilis 150, 574, 603. STYLARIA 156, 283, 289, 293. S. fossularis 284, 285. S. gracilis 281. S. lacustris 65, 106, 155, 284, 285. S. longiseta 290. S. paludosa 284, 285. S. parasitica 293. S. philadelphiana 284. S. proboscidea 94, 284, 636. STyYLINAIS 281. S. proboscidea 284. Stylodrilus 78, 85, 125, 186, 207, 208, 210, 211, 221, 225, 226, 586. 8. gabretae 125, 222. S. heringianus 222. 8. vejdovskii 222. Sutroa 29, 30, 85, 114, 115, 117, 118, 1247, 128, 131, 208, 209, 216, 222, 310, 636. 8. alpestris 223, 224, 8. rostrata 224. Teleudrilus 99, 126, 575, 580, 581, 617, 621, 624. _T. ragazzii 67, 622. Telmatodrilus 108, 115, 118, 228, 229, 230, 231, 232, 233, 240, 241, 268, 265, 270. T. vejdovskii 264. Tetragonurus 102, 193, 195, 692, 697. T. pupa 688, 697. INDEX OF GENERA AND SPECIES 769 THAMNODRILUS 624, 6247, 636, 640, T. gulielmi 640. TITANUS 174, 624, 627, 643. T. brasiliensis 643, 644. T. forquest 644. Trichochaeta 3, 7, 93, 150, 152, 166, 586, 624, 627, 628, 629, 631, 632, 634, 636, 637, 643, 646. T. barbadensis 630, 646, 647. T. hesperidum 3, 7, 630, 646, 647. Trichodrilus 85, 156, 208, 210, 217, 218. T. allobrogum 217. T. pragensis 219. Trigaster 41, 150, 152, 519, 524, 525, 527, 529, 558. T. lankesteri 142, 524, 525, 536, 559, 568. Trinephrus 46, 444, 445, 456, 481. T. dubius 482, 484. T. fastigatus 445, 483. T. mediocris 482, 483. T. tenuis 482, 483. TRITOGENIA 573, 624. T. sulcata 573. Tubifex 2, 6, 23, 30, 75, 88, 94, 95, 106, II4, II5, 117, 118, L119, 12%, 136, 137, 155, 156, 227, 228, 232, 233, 234, 235, 236, 237; 242, 246, 248, 255, 256, 259, 262, 263, 264, 265, 267, 260, 327. T. benedii 260, 261, 262. T. blanchardi 137, 228, 245, 248. T. bonneti 243, 244. T. campanulatus 244. T. coccineus 264, 265, 266. T. deserticola 251. T. diaphanus 245. L. elongatus 250. T. hyalinus 247, 296. 131, 230, 238, 260, 270, 175, 633, 526, 567, 108, 133, 231, 240, 261, 288, Tubifex (continued). T. longicauda 245. T. marinus 244. T. pallidus 313. LT. papillosus 261 262. T. rivulorum 7, 72, 136, 137, 138, 174, 228, 243, 244, 250, 251, 265, 266, 267. T. tubifex 244. Tykonus 150, 152, 624, 627, 628, 629, 631, 632, 634, 635, 637, 638, 648, 650. T. appuni 651. T. grandis 634, 635, 650. Typhaeus 41, 58, 64, 110, 116, 151, 152, 167, 358, 361, 435) 443, 444, 456, 472, 478, 623, 035. T. foveatus 475. T. gammii 472, 478, 475. T. laevis 475, 476. T. masoni 472, 474, 476, 478. T. orientalis 412, 478, 474, 475. Uncinais 206, 275, 276, 294, 303. U. littoralis 33, 72, 277, 278, 279, 294, 295. U. uncinata 296. Unyoria 580, 596. U. papillata 596. Urobenus 64, 120, 150, 152, 166, 361, 624, 626, 627, 629, 631, 632, 634, 661. U. brasiliensis 64, 634, 635, 661. U. papillifer 661, 662. U. teres 662. UROCHAETA 12, 65, 624, 626, 627, 653, 654. U. corethrura 658. U. dubia 658. U. hystrix 470, 658. Uronals 297. Vermiculus 131, 149, 228, 230, 232, 271. V. pilosus 271. VETROVERMIS hyalinus 280. XANTHO 297. A. decapoda 298. Orford PRINTED AT THE CLARENDON PRESS BY HORACE HART PRINTER TO THE UNIVERSITY Clarendon Press Publications. ADLER. 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