A MONOGRAPH 
 
 OF THE 
 
 SILURIAN FOSSILS OF THE GIRVAN DISTRICT 
 
 IN AYRSHIRE 
 
 WITH SPECIAL REFERENCE TO THOSE CONTAINED 
 IN THE “GRAY COLLECTION” 
 
UNIVERSITY OF ILLINOIS 
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SILURIAN FOSSILS 
 
 OF THE 
 
 GIRVAN DISTRICT IN AYRSHIRE 
 
Digitized by the Internet Archive 
 in 2016 
 
 https://archive.org/details/monographofsilur11nich 
 
A MONOGRAPH 
 
 OF THE 
 
 SILURIAN FOSSILS 
 
 IN 
 
 OF THE GIRVAN DISTRICT 
 AYRSHIRE 
 
 WITH SPECIAL REFERENCE TO THOSE CONTAINED 
 IN THE “GRAY COLLECTION” 
 
 BY 
 
 H. ALLEYNE NICHOLSON 
 
 M.D., D.Sc., F.R.S.E. 
 
 PROFESSOR OF NATURAL HISTORY IN THE 
 UNIVERSITY OF ST ANDREWS 
 
 AND 
 
 ROBERT ETHERIDGE, Jun., F.G.S. 
 
 ACTING- PALAEONTOLOGIST TO THE GEOLOGICAL 
 SURVEY OF SCOTLAND 
 
 FASCICULUS /. 
 
 (RHIZOPODA, ACTINOZOA, TRILOBITA) 
 
 WILLIAM BLACKWOOD AND SONS 
 EDINBURGH AND LONDON 
 MDCCCLXXVIII 
 
 * 
 
 All Rights reserved 
 
6~Lo ■*) *\-\ ‘Y’ 
 
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 r' 
 
 GENERAL PREFACE. 
 
 The present work is the first Fasciculus of a detailed descrip- 
 tive catalogue of the fossils of the Silurian area of Girvan, in 
 Ayrshire. The district in question has long been known to be 
 occupied by a great and complicated series of Silurian rocks, 
 the disentanglement and correlation of which has presented 
 exceptional difficulties to the stratigraphical geologist. It has 
 also long been known that the Girvan deposits were largely 
 fossiliferous, but the organic remains have, up to this time, 
 been only very partially worked out, in spite of the excellent 
 descriptions of various forms which have been published by 
 M‘Coy, Salter, Sir C. Wyville Thomson, Mr Davidson, Pro- 
 fessor John Young, and others. As will be seen, indeed, from 
 the bibliographical list which follows, a large number of valu- 
 able papers have been written, dealing with fossils derived 
 from the Girvan area ; but these memoirs only treat of limited 
 portions of the subject ; while they are to be found in separate 
 and often hardly accessible publications. 
 
 Under these circumstances, it appeared to us that a systematic 
 descriptive account of the fossils of the Girvan district would 
 be of value to the geological student, and would be likely to 
 solve some important problems in both palaeontology and 
 geology. We therefore made application to the Royal Society 
 
 \J) 
 
 174563 
 
VI 
 
 GENERAL PREFACE. 
 
 for assistance from the Government grant, and we take this 
 opportunity of expressing our gratitude for the sum of seventy- 
 five pounds, which was allotted to us. This sum was of course 
 insufficient to defray the cost of the first Fasciculus; but with- 
 out this assistance we could not have commenced the work in 
 a satisfactory manner ; and we have to record our best thanks 
 to our friend Robert Gray, Esq., F.R.S.E., to whose generosity 
 we owe further aid. 
 
 Apart, however, from matters of this kind, our greatest debt 
 of gratitude was due to Mrs Robert Gray, without whose co- 
 operation the present work could not have seen the light. By 
 giving us the free and uncontrolled use of her cabinet, Mrs 
 Gray has put us in possession of the most complete series 
 extant of the Silurian fossils of Ayrshire, and has thus enabled 
 us to undertake a systematic review of the interesting and 
 important organic remains of the Girvan area. In this con- 
 nection, we have only to add that our further thanks are due 
 to our friend Charles Lapworth, Esq., F.G.S., who has kindly 
 presented us with some interesting specimens collected by 
 himself in this region. Lastly, a visit to the ground in person 
 has resulted, not only in giving us a direct knowledge of the 
 rocks from which our specimens have been derived, but also in 
 considerably increasing the available material for our work. 
 
PREFACE TO THE FIRST FASCICULUS. 
 
 In the present Fasciculus we have dealt with the Protozoa , 
 the Corals, and a portion of the Crustacea of the Girvan dis- 
 trict, so far as we are at present acquainted with them. In the 
 case of well-known and thoroughly understood forms, on which 
 our specimens throw no new light, we have contented our- 
 selves with simply recording the occurrence of the species, 
 accompanying this with any observations which the Ayrshire 
 examples might call for. In the case of new or imperfectly 
 understood forms, we have always given as full a description 
 as our materials would allow, availing ourselves as far as pos- 
 sible of illustrations in elucidation of the text. 
 
 In connection with the Protozoa, the description of Sac- 
 cammina is from the pen of Henry B. Brady, Esq., F.R.S., on 
 whose unimpeachable authority this interesting type of the 
 Foraminifera can now be asserted to have been in existence in 
 Lower Silurian times. For this and much other kind assist- 
 ance from the same source, we are glad to have this oppor- 
 tunity of publicly expressing our obligation. 
 
 As regards the Corals of the Girvan area, we had unusual 
 difficulties to confront. Though the total number of specimens 
 available for examination was very large, the great majority of 
 these were in such a state of preservation that their external 
 
viii PREFACE TO THE FIRST FASCICULUS. 
 
 characters could only be made out imperfectly, if at all. This 
 necessitated the sectioning of a great number of examples, as 
 well as the preparation of an extensive series of microscopic 
 slides. For this reason, also, the figures which we have given 
 are more largely concerned with the minute internal structure, 
 and less with external features, than has been usual in works 
 dealing with fossil corals. In spite of these disadvantages, the 
 results obtained have been very satisfactory, the coral -fauna 
 proving to be one of high interest. The only other point 
 about the corals worth mentioning is, that we have thought it 
 advisable, in the meanwhile, to retain such forms as CJuztetes 
 and Fis tulip ora in th e Actinozoa, rather than to keep them back 
 till we come to deal with the Polyzoa. It may ultimately be 
 shown that these forms should properly find their place among 
 the latter ; but this view cannot be regarded as proved, and 
 there are considerable difficulties in the way of its adoption. 
 
 The Trilobites, so far as we have at present investigated 
 them, do not call for any particular remarks. On the whole, 
 we are able to support the determinations of previous writers ; 
 and it appears probable that more good work has been accom- 
 plished and published in the direction of this order than of 
 any other, by those who have, up to the present time, inves- 
 tigated the Girvan fauna. We hope to complete the Trilo- 
 bites and other orders of Crustacea in our second Fasciculus, 
 when we intend giving a short chapter upon their relations 
 with the Trilobite faunae of other areas, and particularly their 
 bearing upon the age of the various subdivisions of the Gir- 
 van series. 
 
 In connection with the Trilobites, we are under obligations 
 to R. Etheridge, Esq., F.R.S., and G. Sharman, Esq., of the 
 Museum of Practical Geology, who have rendered us material 
 assistance in the comparison of some of our specimens with 
 those in the valuable collection of that institution. We are 
 
PREFACE TO THE FIRST FASCICULUS. 
 
 IX 
 
 also indebted to Dr J. C. Purves, for suggestions on many 
 points. 
 
 As regards the plates, we have only to say that those deal- 
 ing with the corals were drawn by one of us, and that the 
 others were drawn, and all were put upon the stone, by Mr 
 Charles Berjeau, F.L.S., whose skill as a scientific artist is too 
 well known to need any praise from us, and whose reputation 
 certainly will not suffer from these specimens of his handiwork. 
 Unless otherwise stated, the specimens figured form a part of 
 the “ Gray Collection.” 
 
 St Andrews and Edinburgh, 
 
 October 1878 . 
 

A MONOGRAPH 
 
 OF THE 
 
 SILURIAN FOSSILS OF THE GIRVAN DISTRICT. 
 
 BIBLIOGRAPHY. 
 
 1849. Salter, J. W. — Note on the Fossils from the Limestone on the Stinchar 
 
 River, and from the Slates of Loch Ryan. Quart. Jour. Geol. Soc., 
 v., pp. 13-17, t. 1. 
 
 Mentions the occurrence of seven species in the Stinchar River 
 Limestones, and describes six of them — viz., Pleurotomaria Moorei , 
 Salter ; P. latifasciata , Portlock (?) ; Murchisonia scalar is, Salter ; 
 Euomphalus (?), sp. ind. ; Orthis confinis, Salter ; Illcenus Davisii , 
 Salter. 
 
 1850. M‘Coy, Prof. F.— On some New Genera and Species of Silurian Radiata 
 
 in the Collection of the University of Cambridge. Annals and Mag. 
 Nat. Hist., 2d ser., vi., pp. 270-290. 
 
 Describes Strephodes Craigensis, M‘Coy, Craighead ; Petraia cequi- 
 sulcata, M‘Coy, Mulloch Quarry; Palceopora favosa, M‘Coy, Craighead 
 and Mulloch Quarry. 
 
 Ibid . — On some New Silurian Radiata, loc. cit., pp. 474-477. 
 Describes Palceopora subtilis, M‘Coy, Mulloch Quarry. 
 
 1851. M‘Coy, Prof. F. — On some New Silurian Mollusca. Annals and Mag. 
 
 Nat. Hist., 2d ser., vii., pp. 45-63. 
 
 Describes Orthoceras politum, M‘Coy, Glenwhapple; Bellerophon 
 subdecussatus, M‘Coy, Mulloch Quarry; Trochus Moorei, M‘Coy, 
 Dalquharran. 
 
 Ibid. — id., 2d ser., vii., pp. 387-409. 
 
 Describes Cytheropsis Aldensis, M‘Coy, Aldens ; Hemithyris angus- 
 tifrons, M‘Coy, Mulloch Quarry ; H. nasuta, M‘Coy, Craighead 
 Quarry; Orthisina Scoiica, M‘Coy, Craighead Quarry and Colmonell; 
 and Holopella tenuicincta , M‘Coy, Mulloch Quarry. 
 
 A 
 
BIBLIOGRAPHY. 
 
 1851. Salter, J. W. — List of some of the Silurian Fossils of Ayrshire. Quart. 
 Jour. Geol. Soc., vii., pp. 170-178, plates 8-10. 
 
 Mr Salter gave an exhaustive list of the fossils from the Girvan 
 district, obtained from twelve localities. His list comprised the fol- 
 lowing new species : Diplograpsus bullatus , Niduliius favus , Pleuro- 
 rhynchus dipterus , var. rhomboideus , Maclurea magna , M‘Coy, Ortho- 
 ceras Barrandei. In addition to these, several already known species 
 are noticed. 
 
 1851. Sedgwick, Rev. Prof. — On the Geological Structure and Relation of the 
 
 Frontier Chain of Scotland. Brit, Assoc. Report for 1850, pt. ii., pp. 
 
 1 03- 1 07 ; with List of the Organic Remains by Prof. M‘Coy. 
 
 The rocks of the Girvan district are divided into two subdivisions, 
 a north and south Girvan group. A copious list of fossils, arranged 
 under localities, is given. (This paper was also published in the 
 Edinb. N Phil. Jour., li., p. 250.) 
 
 1852. M‘Coy, Prof. F. — Contributions to British Palaeontology; some New 
 
 Lower Palaeozoic Mollusca. Annals and Mag. Nat. Hist ., 2d ser., 
 x., pp. 189-195. 
 
 Describes Murchisonia cancellatula , M‘Coy, Mulloch Quarry; M, 
 simplex , M‘Coy, Dalquharran ; Maclurea macromphala, M £ Coy, Craig- 
 head ; Ecculiomphalus Scoticus , M‘Coy, Mulloch Quarry. 
 
 1852. M‘Coy, Prof. F.— British Palaeozoic Fossils, fas. ii., p. 351. 
 
 In this valuable work there will be found a list of fossils arranged 
 alphabetically in localities, and preserved in the Woodwardian Mu- 
 seum, Cambridge. For the descriptions of the species the work may 
 itself be referred to ; we shall have occasion to notice many of the 
 forms in question. 
 
 1853. Salter, J. W. — Figures and Descriptions illustrative of British Organic 
 
 Remains. Mem. Geol. Survey United Kingdom , Dec. vii., No. 2, 
 p. 11. 
 
 Describes Cheirurus gelasinosus , Portlock, from the u limestone of 
 Ayrshire.” 
 
 Ibid. — Id., Dec. vii., No. 5. 
 
 Describes Cyphaspis megalops , M‘Coy, and gives as one locality 
 sandstones of Mulloch Quarry, on the authority of M‘Coy. 
 
 1854. Morris, Prof. J. — A Catalogue of British Fossils, comprising the Gen- 
 
 era and Species hitherto described ; with reference to their Geological 
 Distribution, and to the Localities in which they have been found. 
 2d edition, London, 8vo. 
 
 1857. Thomson, Sir C. Wyville. — O n some Species of Acidaspis from the 
 Lower Silurian beds of the South of Scotland. Quart. Jour. Geol. 
 Soc., xiii., pp. 206-210, t. 6. 
 
 Describes four species of Acidaspis from the schists at the base of 
 the “ Graptolite and Orthoceratite flags ” of Penwhapple Glen, Girvan 
 district, which the author considers to be of Upper Bala age — Acidas- 
 pis Lalage, A. hystrix, A. callipareos , and A. unica . 
 
 1864. Salter, J. W. — Figures and Descriptions illustrative of British Organic 
 Remains. Mem. Geol. Survey United Kingdom, Dec. xi., No. 1, p. 8. 
 
BIB LI O GRA PII Y 
 
 3 
 
 Describes Agnostus trinodus , Salter, and gives as one locality Pen- 
 whapple Burn, Girvan district. 
 
 Ibid . — Id., Dec. xi., No. 5, p. 4. 
 
 Describes Staurocephalus (?) unions , Wy. Thomson, Penwhapple 
 Glen, Girvan District. 
 
 Ibid . — A Monograph of British Trilobites, pt. 1, 4to. 
 
 Describes the following species from the Girvan district : Phacops 
 Stokesii, Milne-Edw. ; Cheirurus bimucronatus , Murchison, Mulloch 
 Quarry ; C. octolobatus , M‘Coy, Penwhapple ; C. gelasinosus , Portlock, 
 Craighead limestone. 
 
 1864. Thomson, Sir C. Wyville. — F igures and Descriptions illustrative of 
 
 British Organic Remains. Mem. Gcol. Survey United Kingdom , Dec. 
 xi., No. 6. 
 
 Describes an entirely new form of Trilobite, under the name of 
 Salteria primceva , Wy. Thomson.- — Schists forming the base of the 
 “ Graptolite and Orthoceratite flags,” Penwhapple Glen, Girvan 
 district. 
 
 1865. Salter, J. W. — A Monograph of British Trilobites, pt. 2. 
 
 Describes, from Girvan localities, Staurocephalus globiceps, Portlock ; 
 Calymene Blumenbachii , Brongniart, Mulloch Quarry. 
 
 1866. Davidson, T. — A Monograph of the British Fossil Brachiopoda, pt. vii. 
 
 The Silurian Brachiopoda, No. 1. 
 
 Describes from Girvan localities the following : Lingula attenuate, 
 Sow. • Piscina perrugata , M c Coy ; D . oblongata , Portl. ; D. crassa , 
 Hall; Siphonotreia micula, M‘Coy. 
 
 1867. Murchison, Sir R. I. — Siluria, 4th ed., London, 8vo, pp. 155-157* 
 
 A general outline of the Geology is given, and the occurrence of 
 certain fossils on the Stinchar and Girvan rivers, and at Mulloch 
 Hill, Saugh Hill, and other localities, is mentioned. 
 
 1867. Salter, J. W. — A Monograph of British Trilobites, pt. iv. 
 
 Describes from Girvan localities — Illcenus Bowmani , Salter, Gir- 
 van ; I. Thomsoni, Salter, Mulloch Quarry; I. Macallumi , Salter, Mul- 
 loch Quarry. 
 
 1867. Davidson, T. — A Monograph of the British Fossil Brachiopoda, pt. iii. 
 
 The Silurian Brachiopoda, No. 2. 
 
 Describes Meristella angustifrons , M‘Coy; Atrypa reticularis , Dal- 
 man ; A. imbricata , J. de C. Sow. ; A. (?) hemisphcerica , J. de C. Sow. ; 
 A. (?) Scotica , M‘Coy ; Pentamerus oblongus , J. de C. Sow. ; Rhynchon- 
 ella cuneata , Dalman. 
 
 1868. Geikie, Prof. A. — On the Order of Succession among the Silurian Rocks 
 
 of Scotland. Trans. Geol. Soc. Glasgow , iii., pt. 1, pp. 74-95. 
 
 The Carrick limestones are noticed, and referred to the Caradoc or 
 Bala group ; so also is the Craighead limestone, and again the beds 
 at Ardwell, Piedmont Glen, and Penwhapple Burn. The shelly sand- 
 stones of Drummuck, Mulloch, and Saugh Hill are placed as Llan- 
 dovery. From all the foregoing localities lists of fossils are given. 
 1868. Jones, Prof. T. Rupert. — N otes on the Palaeozoic Bivalved Entomo- 
 straca, No. viii. Annals and Mag. Nat. Hist., 4th ser., ii., pp. 54-62. 
 
4 
 
 BIDL 10 G RAPHY. 
 
 Describes Cythere Aldensis , M‘Coy, from Aldens, to the south-west 
 of Girvan. The species is placed in the genus Cythere , rather than 
 Cytheropsis , with which it had been previously associated. 
 
 1868. Gray, R. — Note on Silurian Fossils from Girvan. Proc. Glasgow Nat. 
 Hist. Soc., i., pt. 1, p. 1 01. 
 
 A list, comprising many of the genera found in the district, is given. 
 
 Ibid. — Note on a Series of Silurian Brachiopoda, from the neigh- 
 bourhood of Girvan, loc. cit ., p. 124. 
 
 The following are mentioned : Lingula Ramsayi , L. attenuata , and 
 Piscina perrugata. 
 
 1868. Young, J. — Remarks on four species of Silurian Brachiopoda, new to 
 Ayrshire, loc. cit., p. 169. 
 
 Notices Siphonotreta micula , Orthis galea , O. alata , and Lingula 
 Ramsayi. 
 
 1868. Young, Prof. J., M.D. — On New Forms of Crustacea from the Silurian 
 Rocks at Girvan. Proc. Nat. Hist. Soc. Glasgow , i., pp. 169-173. 
 
 Describes as a new species Cheirurus trispinosus , from Penkill, and 
 as a new genus and species Solenocaris solenoides. 
 
 1868. Gray, R. — On the occurrence of Ischadites Koenigi in the Silurian Rocks 
 of the Girvan District, loc. cit., p. 197. 
 
 First discovery of this species in the rocks in question. 
 
 1868. Young, J. — Note on a new Brachiopod Shell, Triplesia Grayce, David- 
 son, discovered in the Silurian Strata of the Girvan valley by Mrs 
 Robert Gray, loc. cit., p. 207. 
 
 1 868, Bigsby, Dr J. J. — Thesaurus Siluricus. The Flora and Fauna of the 
 
 Silurian Period, &c. London. 4to. 
 
 A detailed and tabulated list of Silurian fossils generally, amongst 
 which will be found a record of the Girvan forms. 
 
 1869. Gray, R. — Note on Leptcena Youngiana, Davidson, a new Silurian 
 
 Brachiopod Shell from the Girvan District > and also on the Occur- 
 rence of Leper ditia in the same, loc. cit., pt. ii., pp. 230, 231. 
 
 1869. Davidson, T. — A Monograph of the British Fossil Brachiopoda, pt. vii. 
 The Silurian Brachiopoda, No. 3. 
 
 Describes Rhy 7 ichonella nasuta, M‘Coy ; R. nucula, Sow. ; R. 
 Thomsoni, Davidson ; R. Salieri, Dav. ; Triplesia Grayce, Dav. ; 
 Atrypa (?) incerta, Dav. ; Orthis Bouchardii, Dav. ; O. elegantula, 
 Dalman ; O. Girvanensis, Dav. ; O. vespertilio, J. de C. Sow. ; O. calli- 
 gramma, Dalman. 
 
 1869. Geikie, Prof. A. — Lists of Fossils, determined by Mr R. Etheridge, 
 from (a) the Craighead limestone, (b) the Ladyburn (Drummuck) 
 section, and (c) from the lower Llandovery Rocks of Kirk Hill, 
 Girvan district. Mem . Geol. Survey Scotland, Expl. sheet 14 (pp. 9- 
 10). 
 
 Eleven species are mentioned from the first locality, six from the 
 second, and eight from the third. 
 
 Ibid. — Lists of Fossils, determined by Mr R. Etheridge, (a) from 
 the Aldens limestone, and (b) from Ardmillan Brae, in the Girvan 
 district. Mem. Geol. Survey Scotland, Expl. sheet 7 (pp. 9- to). 
 
BIBLIOGRAPHY. 
 
 5 
 
 From the first locality nine species are mentioned, and from the 
 second forty-five and a few doubtful ones. 
 
 1871. Davidson, T. — A Monograph of the British Fossil Brachiopoda, pt. vii. 
 The Silurian Brachiopoda, No. 4. 
 
 Describes Orthis turgida , M‘Coy ; O. confinis , Salter ; O. insularis, 
 Eichwald (?) ; Strophomena rhomboidalis , Wahl. ; S. retroflexa , Salter ; 
 S. antiquata , Sow. ; S. corrugatella , Dav. ; S. grandis , Sow . ; Leptcena 
 Youngiana * Dav. ; L. quinquecostata, M‘Coy ; Z. sericea , Sow. ; Z. 
 tenuicincta , M‘Coy. 
 
 1S73. Etheridge, R., with Prof. J. Young and R. Etheridge, jun. — List of 
 Fossils collected by the Geological Survey from the Silurian Rocks 
 of the south-west of Ayrshire. Mem. Geol. Survey Scotland, Expl. sheet 
 
 3 (pp- 29-34)- 
 
 The Fossils are arranged under thirty-one localities. 
 
 1873. Lapworth, C. — On the Silurian Rocks of the south of Scotland. Trans. 
 Geol. Soc. Glasgow , iv., pt. 2 (pp. 164-174). 
 
 In the appendix to this paper will be found 1 Lists of the Fossils of 
 the various subdivisions of the south Scottish Silurians,’ the ninth 
 paragraph of which relates exclusively to the Girvan series. 
 
 1875. Young, J. — Notes on the Genera of Extinct Fossil Shells, Bellerophon 
 
 and Porcellia ; their classification amongst the Mollusca, and their 
 distribution in the Silurian and Carboniferous strata of the west of 
 Scotland. Proc. Nat. Hist. Soc. Glasgow , 1875, ii., pt. L P- 1 6. 
 
 States that four species of Bellerophon occur in the Girvan Silurian 
 beds. 
 
 Id . — Note on a small collection of Fossil Brachiopoda from the 
 neighbourhood of Girvan. Loc. cit ., p. 21. 
 
 Records the occurrence of Atrypa incerta , Rhyfichonella cemula , R. 
 Thomsoni , R. Weaveri , Orthis Bouchardii , O. vespertilio , O. calli- 
 gramma , var. Scotica , O. elegantula , Triplesia Gray os, Strophomena im- 
 brex , Leptcena Youngiana , Z. tenuicincta , Z. sericea , and Strophomena 
 Grayi. 
 
 Young, Dr J. — Note on a new species of Crustacean, belonging to 
 the genus Solenocaris , from Silurian strata near Girvan, and on frag- 
 ments, probably the appendages of a Trilobite or Limuloid Crustacean. 
 Loc. cit., p. 66. 
 
 1876. Lapworth, C. — On Scottish Monograptidae, pt. 8. Geol. Mag., Dec. 2, 
 
 1876, iii., pp. 544-55 2 - 
 
 Describes Cyrtograptus Grayed, a new species from the Penwhapple 
 Glen beds, near Girvan. 
 
 1876. Young, J. — Notes on a series of Fossils from the Silurian Rocks of the 
 Girvan Valley. Proc. Nat. Hist. Soc. Glasgow, ii., pt. 2, p. 166. 
 
 Notes the occurrence in the Gray collection of Bellerophon dilatatus, 
 Murchisonia obscura, Holopella obsoleta , Scalites angulatus, Lingula 
 quadrata , Orthis biforata , Rliynchonella Salteri, Orthis Girvanensis, 
 and Acidaspis Brightii. 
 
 Id . — Note on a series of Trilobites of Caradoc age from the Silu - 
 rian strata of the Girvan Valley. Loc. cit., p. 179. 
 
6 
 
 BIBLIOGRAPHY. 
 
 Notes the identification of the following species in the Gray collec- 
 tion — viz., Illcenus Bowmani , I. Thomsoni, I. Barriensis , Cybele 
 verrucosa , Staurocephalus (?) unicus , Proetus latifrons , Cheirurus latifrons , 
 Zethus rugosus, and Odontopleura ovata (?) 
 
 Id. — Note on a series of Graptolites from the Silurian strata of 
 the Girvan Valley. Loc. cit ., p. 182. 
 
 The following are stated by Mr Young to be in the Gray collection 
 from Penwhapple Glen — viz., Graptolithus priodon, G. Sedgwickii , G. 
 colonus , Cyrtograptics Grayianus , Lapworth ; and Dicranograptus 
 tardiusculus , Lapworth. 
 
 Id . — Note on Crinoid remains from the Silurian strata of the 
 Girvan district. Loc. cit., p. 216. 
 
 Obtained from two localities, Craighead and Balcletchie. 
 
 Young, Prof. J. — Note on a Silurian Fossil from the Girvan dis- 
 trict. Loc. cit., p. 223. 
 
 The specimen was referred to Salter’s genus Pterotheca. 
 
 1876. Armstrong, J., with J. Young and D. Robertson. — Catalogue of the 
 
 Western Scottish Fossils. Glasgow. 8vo (pp. 12-22). 
 
 Gives a list of fossils, zoologically arranged, of the Girvan district, 
 with localities, compiled from various sources. 
 
 1877. Davidson, T. — Notes on four species of Scottish Lower Silurian Brachi- 
 
 opoda. — Geol. Mag., Dec. 2, iv., pp. 13-17, t. 2. 
 
 Describes Siphonotreta Scotica, Dav., Craighead Quarry ; Lingula 
 quadrata, Eichwald, Craighead Quarry; and L. Canadensis, Billings, 
 Balcletchie, near Girvan. 
 
 1877. Woodward, Dr H. — A Catalogue of British Fossil Crustacea, with 
 their Synonyms, and the Range in Time of each Genus and Order. 
 London. 8vo. 
 
 1877. Nicholson, Prof. H. A., and R. Etheridge, jun. — On Prasopora 
 
 Grayoe, a New Genus and Species of Silurian Corals. Annals and 
 Mag. Nat. Hist., 4th ser., xx., pp. 388-392. 
 
 A small, peculiar, button-shaped little coral, having much the 
 external appearance of a Favosites. The internal structure is, how- 
 ever, unique, and quite different from that of the latter. Abundant at 
 Craighead Quarry. 
 
 1878. Etheridge, R., and E. T. Newton. — A Catalogue of the Cambrian and 
 
 Silurian Fossils in the Museum of Practical Geology. London. 
 1878. 8vo. 
 
 Many species from the Girvan ground are given, with their 
 localities. 
 
 Etheridge, R., jun. — Notes on Silurian Fossils from Ayrshire. ( Proc . 
 R. Physical Soc. Edinb., 1878, iv., pt. iii., pp. 164-177, t. 2.) 
 
 Describes as new species Turrilepas Scotica and Acidaspis Gray a; 
 and as a new genus and species Pinnocaris Lapworthi. 
 
LOCALITIES. 
 
 7 
 
 Localities at which Fossils have been Collected in the Girvan Dis- 
 trict, and Referred to in the succeeding Pages of this Work. 
 
 1. High Mains, about 6 miles N.E. of Girvan. 
 
 2. Kirk Hill, near last locality. 
 
 3. Littleburn, S.W. of High Mains. 
 
 4. Quarry at pond, S.W. of Rough Neuk, about 6 miles N.E. of Girvan. 
 
 5. Quarry at Rough Neuk. 
 
 6. Roadside, near Old Fort at Kirk Hill. 
 
 7. Quarry on roadside, east of last locality. 
 
 8. Littleburn, Quarrel Hill, near Auldthorn, about 6 miles N.E. of Girvan. 
 
 9. Drummuck Burn, about 4 miles N.E. of Girvan. 
 
 10. Lady Burn, above Drummuck. 
 
 11. Lady Burn, opposite Threave. 
 
 12. Craighead Quarry, about 3 miles N.E. of Girvan. 
 
 13. Craigens, near Kirk Hill, about 5^4 miles N.E. of Girvan. 
 
 14. Ardmillan Brae, about 2 }4 miles S.W. of Girvan. 
 
 15. Piedmont Glen, S. of Girvan. 
 
 16. Laggan Burn, S.E. of Girvan. 
 
 1 7. Ardwell Shore, about 4 miles S.W. of Girvan. 
 
 18. Penwhapple Glen, E. of Girvan. 
 
 19. Saugh Hill, about 1 mile E. of Girvan. 
 
 20. Camregan Plantation, about 2 miles E. of Girvan. 
 
 21. Balcletchie, about 4 miles E. of Girvan. 
 
 22. Tramitchell, about 3 miles S.E. of Girvan. 
 
 23. Barbae, nearly 3 miles S.E. of Girvan. 
 
 24. Pinmacher, about 2)4 miles S. of Girvan. 
 
 25. Letterpin, nearly 4 miles S. of Girvan. 
 
 26. Auchensoul, about 5 miles S.E. of Girvan. 
 
 27. Aldons, on the Stinchar R., about 5 miles S. of Girvan. 
 
 28. Head of burn passing Bargany Pond, about 6 miles east by north of 
 
 Girvan. 
 
 29. Hillside opposite Blair farm, about 8^4 miles N.E. of Girvan. 
 
 30. Quarry on roadside near Knockgardner, about 10 miles N.E. of 
 
 Girvan. 
 
 31. Mulloch Hill, 4 miles N.E. of Girvan. 
 
 32. Penkill, 334 miles N.E. of Girvan. 
 
 33. Colmonell, on the Stinchar R., about 7 miles S. of Girvan. 
 
 34. Braes, about i}4 rnile E. of Girvan. 
 
 35. Knockdolian Mountain, near Colmonell, on the Stinchar R., S. of 
 
 Girvan. 
 
 36. Cuddystone Glen, about 1 mile S. of Girvan. 
 
 37. Knockgerran, about miles E. of Girvan. 
 
 38. Shalloch Mill, on sea-shore, i}4 mile S. of Girvan. 
 
 39. Burn a little south of Shalloch Mill (Graptolites, &c.) 
 
 40. Ardmillan shore, 2*4 miles S. of Girvan. 
 

DESCRIPTION OF THE SPECIES. 
 
 PLANTAE. 
 
 ORDER ALGALES. 
 
 Genus Chondrites, Sternberg, 1833. 
 
 Chondrites, sp. 
 
 (Near Chondrites verisimilis , Salter, Mem. Geol. Survey, Scotland, No. 32, 
 p. 134, t. 2, f. 1 and 2.) 
 
 Obs . — A single, small, and imperfect fragment is in the Gray 
 collection, which has all the appearance of a Chondrites , and 
 very near the above species. The probability of this fact is 
 increased by the occurrence at another locality in the Girvan 
 area of a form which cannot be distinguished from C. verisimilis , 
 Salter. The specimen in question was found by Mr A. Mac- 
 conochie, near Bargany Pond, about six miles north-west of 
 Girvan, and is in the collection of the Geological Survey of 
 Scotland. 1 In the ‘ Catalogue of Western Scottish Fossils,’ 2 
 by Messrs Armstrong, Young, and Robertson, C. verisimilis is 
 relegated to the Annelida, a step to which we must express our 
 unqualified dissent, as an inspection of Salter’s figure will at 
 once show that it can have no possible connection with that 
 class. 
 
 Locality . — Penkill, in a fine-grained, slightly micaceous shale, 
 (Gray collection). 
 
 1 Etheridge, Mem. Geol. Survey, Scot., Expl. 3, p. 34. 
 
 2 Glasgow, 1876, p. 15. 
 
IO 
 
 R HI ZO POD A . 
 
 
 SUB-KINGDOM PROTOZOA. 
 
 CLASS RHIZOPODA. 
 
 Genus Nidulites, Salter, 1851. 
 
 Nidulites , Salter, Quart. Jour. Geol. Soc., 1851, vii. 174. 
 
 ,, Morris, Cat. Brit. Foss., 1854, 2d ed., p. 362. 
 
 „ Bigsby, Thesaurus Sil., 1868, p. 4. 
 
 „ Salter, Cat. Camb. and Sil. Foss., Woodwardian Mus., Cambg., 
 1873, p. 72. 
 
 (Compare Cyclocrinus , Eichwald, Lethaea Rossica, i. 637 ; Pasceotus , Billings, 
 Logan’s Geol. Survey Report, Canada, for 1856, p. 342 ; Pal. Fossils, Canada, 
 p. 390, f. 366, 367 ; Cat. Sil. Foss. I. of Anticosti, p. 69; SpJnzrospongia , Salter, 
 Pal. Niti in the N. Himalaya, 1865, p. 48; Cat. Camb. Sil. Foss., Wood- 
 wardian Mus., Cambg., 1873, P- 4°-) 
 
 (a) Gen. char. — Body pyriform or sphaeroidal (?), pedun- 
 culate, with an outer integument of hexagonal calcareous 
 plates, articulated (or fused ?) by their edges. Each plate is 
 deeply convex, with the convexity directed to the hollow 
 interior of the sphere, into which it further sends a small 
 central papilla or styliform projection, leaving a pit in the 
 cast. The edges of the plates are prominent, thus closely 
 resembling honeycomb. Plates to a certain extent variable 
 in size, decreasing towards the contracted base. Apertures, 
 none (?). Traces of an enclosing sac or investment. Per- 
 fect condition of organism unknown. 
 
 (b) History. — Mr Salter described Nidulites as oval or 
 round plates, about two inches in diameter, spreading from 
 a centre of attachment into a flattened irregularly wavy form, 
 the entire surface of both the upper and under sides being 
 covered with hexagonal cups. The edges of the latter were 
 stated to be smooth and even with the general surface, their 
 bases rounded, and usually with a central puncture or pit. A 
 narrow space was always found to exist between the two series 
 of cups, which Mr Salter considered to be occupied in the 
 perfect organism by a membrane giving attachment to the 
 
NIDULITES. 
 
 1 1 
 
 cups, probably by means of the punctures before mentioned. 
 The lower surface of the cups themselves appears to have been 
 somewhat wrinkled. Their bodies were supposed by Mr 
 Salter to be the egg-ribbons of marine Gasteropoda, probably 
 of a genus nearly allied to Natica, an idea suggested to him by 
 Professor Milne-Edwards. Mr Salter adds that one condition 
 of Nidulites was figured by Professor M‘Coy as a specimen of 
 the latter’s Palceopora favosa . 
 
 Professor Morris in his ‘ Catalogue ’ placed Nidulites 
 amongst the “ Incertse sedis,” expressing thereby his appre- 
 ciation of the difficulties in assigning to it any definite 
 systematic position. 
 
 In the palaeontological notes attached to the third edition 
 of Sir R. Murchison’s ‘ Siluria,’ furnished by Mr Salter, 
 Nidulites is in one place doubtfully referred to the Polyzoa , 1 
 whilst in another his original theory is given up, and Mr Salter 
 evidently conceived that it might possibly be an Amorpho- 
 zoon . 2 He states that he had not met with any upper plate or 
 covering to the cells, which appear to have been quite open. 
 
 In the ‘Palaeontology of Niti ,’ 3 Salter remarks upon the 
 relation of Nidulites to his genus Sphcerospongia , and the 
 probable sponge nature of both of them. 
 
 In the Cambridge Catalogue , 4 Salter again compares Nidu- 
 lites to his genus Sphcerospongia. 
 
 (c) Obs. — Nidulites favus is only known to us in the condi- 
 tion of casts. It occurs in the form of irregularly oval, globu- 
 lar, or pyriform masses, when at all approaching the complete 
 outline, or as flat expansions when in a fragmentary state. 
 The true test, shell, calyx, or skeleton, by whichever name the 
 reader may think fit to call it, is never met with, but we either 
 have a globular body consisting of a series of moulds in the 
 form of hexagonal cups, or, on the other hand, concave or 
 flattened expansions, consisting of rounded hexagonal promi- 
 
 1 Siluria, 1867, 3d ed., p. 188. 2 Ibid., p. 208. 
 
 3 Pal. of Niti in the Northern Himalaya, &c. Calcutta, 1865, 8vo, p. 48. 
 
 4 P. 72, 
 
RHIZOPODA. 
 
 I 2 
 
 nences, often ranged in quincunx. Whenever these two condi- 
 tions are found in apposition, a narrow space is always left 
 between them, which, according to Salters view, was occupied 
 by a connecting membrane or lamina, but which we conceive 
 to represent the position of the actual calcareous skeleton. It 
 must also be borne in mind that Mr Salter believed the cups 
 were placed back to back, adhering to the membrane repre- 
 sented by the space in question — a conception which we think 
 resulted from an examination of a number of examples crushed 
 together. The convex casts of the hexagonal cups are often, 
 but by no means in every case, provided with central papillae, 
 which are themselves the casts of pits existing in the cup- 
 moulds; but, as in the case of the papillae or styliform processes, 
 their presence is not constant. In the masses of the convex 
 casts there is a tendency in the respective hexagons for the 
 surface to peel off in concentric layers. When the cups are 
 filled with matrix to a similar level, and the observer is looking 
 down on the specimen, the appearance of a series of roughly 
 hexagonal plates is presented. 
 
 The slight irregularities visible in the form of the globose or 
 pyriform body of Nidulites lead us to suspect that the test pos- 
 sessed a certain amount of flexibility when in the living state. 
 We have not seen an individual perfect in outline, but the 
 figures given on Plate IX. leave little doubt as to the true form 
 of the organism ; neither do we doubt that there existed a 
 peduncle or short stem, especially when we take into consider- 
 ation its remarkable resemblance to its allies Pasceohts , Billings, 
 and Sphcerospongia , Salter. This is to a great extent borne 
 out by a specimen from Haverfordwest, in the Museum of 
 Practical Geology, which shows, at a point we take to be the 
 crushed-in base, the remains of a peduncle, with, spreading out 
 from it on all sides, the remains of an enclosing membrane or 
 epidermal integument. A single specimen in the Gray collec- 
 tion shows this to a small extent. In the examination of a 
 large series of Nidulites fragments, our great endeavour has 
 been all along to obtain some definite insight into the charac- 
 
NIDULITES. 
 
 3 
 
 ters of the true skeleton ; but, with the exception of one speci- 
 men, our efforts have been quite unsuccessful. The specimen 
 in question has enabled Mr F. G. Cuttell to prepare us a 
 microscopic section showing the space previously mentioned 
 as occurring between the cups and their casts occupied by car- 
 bonate of lime, but merely as an infilling, and not as the actual 
 skeleton, since it consists of crystalline calcite. 
 
 (d) Affinities. — The nearest affinities of Nidulites are 
 probably with Cyclocrinites, Eichwald, and Receptacnlites , 
 Defrance, but its relationships are extremely obscure. Two 
 other forms to which Nidulites is even, perhaps, more closely 
 allied, are Splicer ospongia, Salter, and Pasceolus, Billings . 1 It 
 is necessary for us to enter somewhat more into details 
 connected with these genera before closing our remarks on 
 Nidulites . 
 
 The genus Pasceolus (fig. i a and b) was described by the 
 late Mr Billings as a body possessing “an ovate or globular 
 form covered with an integument of small polygonal plates (?), 
 and with one or more circular apertures. ... At one end 
 there is a narrow prolongation, which, most probably, con- 
 stituted the pedicle by which the body was attached to the 
 bottom. ... A little below the mid-height of the body 
 there is a small circular elevation which appears to mark the 
 place of an orifice. . . . No sutures can be distinguished, 
 
 and the form of the plates can only be made out as so many 
 obscure convexities on the outside. . . . The cast shows 
 
 the place of the sutures most distinctly, and that the plates 
 were deeply concave on the inside. . . . The whole surface 
 of the cast of the fossil is covered with small convex elevations. 
 
 Many of these elevations have a small round knob in 
 the centre, with an obscure ridge radiating to the middle of 
 each of the sides.” 1 Mr Billings at one time referred Pasceolus 
 to the Tunicata, but in his second description he considers its 
 true zoological position to be “ quite undecided.” 2 
 
 1 Pal. Foss. Canada, i. 390, 391. 
 
 2 Ibid., p. 392. 
 
T 4 
 
 RHIZOPODA . 
 
 Messrs A. E. Verrill and W. H. Niles have referred , 1 and 
 so, indeed, has Mr Billings , 2 to the resemblance of Pasceolus 
 to Cyclocrinites, Eichwald. 
 
 Professor Verrill states that the exterior of Pasceolus “was 
 formed by a shell of considerable thickness, composed of small 
 hexagonal and pentagonal plates or prisms, having the outer 
 
 Fig. l. — a , Pasceolus Halli , Billings, of the natural size, from the Middle Silurian of Anticosti. 
 
 b, Pasceolus globosus, Billings, from the Trenton Limestone of Ottawa, of the natural size. 
 
 c, Sphcerospongia melliflua , Salt., from the Silurian of India, of the natural size, d, Four 
 of the integumentary plates of the same, enlarged, e, Cyclocrinus Spaskii , Eichwald, from 
 the Silurian of Esthland, natural size, f Part of a vertical section of the same, of the 
 natural size, showing the thickness of the integument, g, Part of the test, enlarged. /z, 
 Portion of the mould of the inner surface of the same, enlarged, z, Diagrammatic repre- 
 sentation of a vertical section of Nidulites favus , Salt. , the central cavity being supposed 
 to be filled with the matrix. ( a and b are after Billings, c and d are after Salter, and <?, f 
 g, and h are after Roemer.) 
 
 surface marked with raised radiating lines. Moreover, some 
 of the specimens had the lateral openings well preserved, and 
 surrounded by six plates differing in form from the rest/' 
 From this we gather that Verrill considered Pasceolus to be a 
 
 1 Proc. Nat. Hist. Soc. Boston, 1864-66, x. p. 19. 
 
 2 Pal. Foss., i. 392. 
 
NIDULITES. 
 
 i5 
 
 Cystidean : indeed, his colleague, Mr Niles, supported him in 
 this view, and definitely referred Pasceolus to Cyclocrinites, 
 Eichwald. It will be noticed that in Professor VerrilFs de- 
 scription, a considerable advance is made in the structure of 
 Pasceolus : we have prisms introduced, and the lateral openings 
 surrounded by six plates, dissimilar to the others forming the 
 test. To these criticisms Billings replied at some length , 1 
 dissenting from the views expressed by the above authors. 
 He further pointed out that Pasceolus Halli is covered with a 
 thin, translucent, horny, wrinkled integument, and also noticed 
 its relationship to the form at present under consideration, in 
 these words — “ It may be that these bodies are akin to Salter’s 
 Nidulites .” 2 
 
 We now pass on to Cyclocrinus (fig. 1, e-h ), small globular 
 bodies, covered with hexagonal or pentagonal plates, and 
 placed by Eichwald in the Cystoidea. Each of the plates has 
 a tubercle in the centre, as before described in some con- 
 ditions of Pasceolus , and similar obscure radiating ridges ; the 
 apex is provided with an orifice, considered to be oral, and the 
 opposite extremity is provided with a small pedicle. There is 
 also an incrustation present in one of the figured specimens, 
 probably analogous to that mentioned by Billings in Pasceolus 
 Halli. The latter author, although admitting the possibility of 
 Cystidean affinities, shows that some of the essential structures 
 of that order are wanting in Cyclocrinus . Eichwald further 
 
 states that the plates of his genus rest on a common calcareous 
 base, which passes between them, and fills the interstices . 3 
 
 Dr F. von Roemer 4 has supplemented Eichwald’s figures by 
 giving a section of Cyclocrinus (fig. if), in which are the plates 
 of the test represented in the form of small cups with delicate 
 styliform processes ; and in another figure, which we suppose 
 represents a cast of the cup- like plates, the place of the pro- 
 cesses is represented in each by a median puncture. By 
 Roemer Cyclocrinus is referred to the Receptaculitidae. From 
 
 1 Cat. Sil. Foss. I. of Anticosti, 1866, p. 71. 2 Ibid. 
 
 3 Lethaea Rossica, i. p. 638. 4 Lethaea geognostica, 1876, Atlas, t. 3, f. 21, a-e. 
 
RHIZOrODA. 
 
 16 
 
 the points we have brought forward, it is quite dear that even 
 on Mr Billings’s diagnosis there is a dose resemblance between 
 Pasceolus and Cyclocrinus , and if we accept the remarks of 
 Messrs Verrill and Niles, there is a still closer one; however, 
 if Cyclocrinus really possesses an apical aperture, then, as 
 Billings has truly said, “ it must * be a distinct genus from 
 Pasceolus .” 1 U nfortunately we have no material at our dis- 
 posal to enable us to express an opinion; we can only notice the 
 relation of the two genera, one to the other, and to Nidulites. 
 
 We have now to consider the third genus, Sphcerospongia , 
 Salter (fig. i c and d), with which we are acquainted only from 
 figures and descriptions given by Mr Salter. It was proposed 
 in the “Geology of the Neighbourhood of Edinburgh ,” 1 2 and 
 described in the ‘ Palaeontology of Niti,’ the type of the genus 
 being the large Sphceronites tesselatus , Phill. Sphcerospongia, 
 then, is an oval or pyriform body, hollow within, composed of 
 a series of hexagonal or pentagonal plates, with sinuous mar- 
 gins, united laterally, and each bearing a central pit or depres- 
 sion. The walls are strengthened internally by longitudinal 
 bars or ribs. The internal structure has been illustrated by 
 Mr Pengelly . 3 Mr Billings has remarked 4 upon the resem- 
 blance between Pasceolus and S. tesselatus , Phill . 5 — viz., the 
 same semi-pyriform outline and mammillated hexagonal plates. 
 Mr Pengelly’s figure, if it be the same fossil as the latter, rep- 
 resents the interior, with a network of vertical and longitu- 
 dinal ribs. 
 
 Nidulites agrees with Pasceolus and Sphcerospongia in the 
 ovate, globular, or pyriform body, and probable pedicle, in the 
 form of the plates composing the test, and, so far as the former 
 is concerned, in the presence of the papillae in the casts of the 
 concave plates. There is, however, this very marked differ- 
 ence : in Pasceolus the plates are described as concave or cup- 
 like, with the concavity directed towards the interior of the 
 
 1 Cat. Sil. Foss. I. of Anticosti, p. 71. 
 
 2 Mems. Geol. Survey, Scot. No. 32, p. 136. 3 Geologist, 1861, iv. 340, 341. 
 
 4 Pal. Foss. Canada, p. 392. 5 Pal. Foss. Devon., t. 59. 
 
NID ULITES. 
 
 *7 
 
 body ; but in Nidulites just the contrary occurs, — the plates are 
 concave externally, and convex towards the hollow interior. 
 The result of this is, that whereas the styliform processes of the 
 cup-like plates in Nidulites are exhibited as papillae on the whole 
 concave casts of the organism, in Pasceolus they are seen on 
 the convex cast of the interior of the body, producing in the 
 perfect organism a very marked and peculiar structural differ- 
 ence. Moreover, if there are “circular apertures” or “circular 
 elevations ” in Pasceolus , there are none, nor any trace of any, 
 so far as our observation has gone, in the numerous specimens 
 of Nidulites examined by us. The absence of openings, again, 
 will at once separate the latter from Cyclocrinus y if there exists 
 one in the summit of that genus, as described by Eichwald, 
 and another on the sides with modified plates, as observed by 
 V errill and N iles, who make Cyclocrinus and Pasceolus identical. 
 On the other hand, with the aid of Roemer’s well-executed fig- 
 ures, we observe that the feature which served as a point of de- 
 parture between Nidulites and Pasceolus has, in the case of the 
 former and Cyclocrinus , quite an opposite effect — in other words, 
 the plates of the test are convex towards the hollow interior, 
 and are prolonged inwards as a styliform process in a similar 
 manner. This would produce in external casts similar papillae 
 to those seen on the surface of that particular condition of 
 Nidulites . There is no trace of radiating striae on the casts of 
 Nidulites , as shown in Cyclocrinus and described in Pasceolus. 
 
 We are unfortunately precluded from doing more than call- 
 ing attention to these facts. Much progress yet requires to 
 be made in our knowledge of Pasceolus , Cyclocrinus , Sphce- 
 rospongia , and Nidulites , before their exact relation to one 
 another, and to the lower sections of Palaeozoic Invertebrates, 
 can be determined. That they are all congeneric we think 
 there is little doubt, but which is identical with which it is at 
 present quite impossible to tell ; but so far as Nidulites is 
 concerned, the balance of evidence appears to indicate Pasceo- 
 lus and Sphcerospongia (as typified by S. hospitalis, Salter) as 
 its nearest connections. As regards the systematic position 
 
 B 
 
i8 
 
 RHIZOPODA . 
 
 of these forms, we are inclined to consider them very near to 
 
 Rcccptaculites. 
 
 Nidulites favus, Salter. 
 
 (PI. IX. figs. 15-22.) 
 
 N favus , Salter, Quart. Jour. Geol. Soc., 1851, vii. 174, t. 9, f. 16, 17. 
 
 Palocopoi'a favosa (pars), M‘Coy, Brit. Pal. Foss., 1851, p. 15, t. 1 C, f. 3, 
 c and d (excl. f. 3, a and b). 
 
 N favus , Morris, Cat. Brit. Foss., 1854, 2d ed., p. 362. 
 
 ,, „ Huxley and Etheridge, Cat. Foss., Mus. Pract. Geol., 1865, p. 34. 
 
 „ „ Salter, in Murchison’s Siluria, 1867, 4th ed., pp. 188, 208, 509, 
 
 foss. 30. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 4. 
 
 „ „ Salter, Cat. Camb. and Sil. Foss., Woodvvardian Mus., Cambg., 
 
 1873, P* 72, fig- 
 
 Spec. char. — The characters of the species are essentially 
 those given under the generic heading, and need not be re- 
 peated here. 
 
 Obs . — Prof. M‘Coy described N. favus as a condition of 
 his Palceopora favosa , and both mentioned and figured all the 
 essential characters of the form as then known. Examination 
 enables us to quite corroborate Mr Salter in the separation of 
 the two species, for P. favosa is a common fossil at Craighead 
 Ouarry, near Girvan, and we have examined many specimens 
 of it . 1 
 
 A single individual, with the cups very much smaller in size, 
 would almost induce us to found a new species for its recep- 
 tion, were it not that in one of the most complete representa- 
 tions 2 known to us of the very closely allied, if not identical, 
 genus Pasceolus , the plates, or cups, become gradually smaller 
 in size towards the base (of attachment ?). The specimen in 
 question, therefore, may be only a portion of the larger N. favus , 
 although we are inclined to an opposite view. Should this 
 example from Balcletchie ultimately prove to be distinct, we 
 would propose for it the name of Nidulites parvus , Eth. and 
 Nich. 
 
 Loc. and Horizon. — Mulloch Hill, in a fine-grained buff to 
 
 1 See post, under Lyopora favosa. 2 Illinois Survey Report, iii. t. 5, f. 2 a . 
 
IS CH A DJTES. 
 
 1 9 
 
 liver-coloured sandstone of Upper Silurian age. (Gray Coll) 
 It is of frequent occurrence in a somewhat similar rock at 
 Haverfordwest, N. Wales, of Llandovery age. N. favus has 
 also been met with at the following further localities in the 
 Girvan district: High Mains, Kirk Hill, Roughneuk Quarry, 
 Craighead Quarry, Craigens, Barbae, and Letterpin (Geological 
 Survey, collected by the late Mr R. Gibbs, and Mr A. Mac- 
 conochie). 1 
 
 Genus Ischadites, Murchison, 1839. 
 
 Ischadites, Murchison, Sil. Syst., 1839, pp. 697, 698. 
 
 ,, Eichwald, Lethsea Rossica, i860, v. 435. 
 
 „ Salter, Mem. Geol. Survey, 1866, iii. 282. 
 
 ,, Bigsby, Thesaurus Siluricus, 1868, p. 3. 
 
 „ Salter, Cat. Camb. Sil. Foss., Woodwardian Mus., Cambg., 1873, 
 pp. 40, 100. 
 
 Gen . char. — Globular, pedunculated bodies ; surface sub- 
 divided by a number of direct or wavy ridges, crossing one 
 another at oblique angles, into a series of rhomboidal or 
 lozenge-shaped spaces ; the peduncle terminating in a series of 
 branching and diverging root -fibres; rhomboidal spaces sub- 
 divided by two lesser ridges crossing them at their greater and 
 lesser diameters. Aperture situated at the apex. 
 
 Obs. — So far as we are aware, very little has been done to 
 elucidate this genus. Many authors have united it with Recep- 
 taculites , Defrance, but although admitting that they appear to 
 be very closely connected, and perhaps identical, we retain the . 
 name until the form has been more thoroughly worked out, 
 and its characters better defined. The necessary material for 
 this purpose is not accessible to us, and we cannot, therefore, 
 offer more than a general opinion just now. Ischadites was 
 considered by Konig to be an Ascidian allied to his genus 
 Leucophthalmus ; 2 by Salter 3 to be a regular sponge with ver- 
 tical and transverse bundles of fibres resembling his genus 
 
 1 Etheridge, Young, and Etheridge, Mem. Geol. Survey, Expl. 3, 1873, pp. 29-33; 
 Armstrong, Young, and Robertson, Cat. W. Scot. Foss., 1876, p. 13. 
 
 2 leones Fossilium Sectiles, p. 1. 3 Mem. Geol. Survey, Scot., No. 32, p. 136. 
 
20 
 
 RH 1 Z 0 P 0 DA. 
 
 Sphcerospongia , and having roots 1 and an aperture like the 
 recent genus Grantia ; whilst by the larger majority of writers 
 Ischadites has been, as stated above, referred to Receptaculites. 
 The late Mr Billings stated 2 that the sculpture of Ischadites 
 and of his Receptaculites Canadensis was quite similar. 
 
 According to Salter, the genus occurs in the Upper Llan- 
 deilo, Caradoc, Woolhope, Wenlock, and Ludlow beds. 
 
 The following are the British species known : — 
 
 I. antiquuSy Salter, Mem. Geol. Survey, 1866, iii. 282; Upper Llandeilo, 
 N. Wales. 
 
 I. Grindrodi, Salter, Bigsby’s Thesaurus Siluricus, 1868, p. 4 ; Woolhope, &c. 
 
 I. Konigii , Murchison, Sil. Syst, 1839, p. 697 ; Wenlock and Ludlow; Dud- 
 ley, Malvern, &c-. 
 
 /. micropora , Salter, Cat. Camb. Sil. Foss., Woodwardian Mus., Cambg., 
 p. 40 ; N. Wales. 
 
 /. tesselatus, Salter, MS., Siluria, 1867, 4th ed., p. 509; Caradoc. 
 
 Ischadites Konigii, Murchison. 
 
 /. Konigii , Murchison, Sil. Syst., 1839, p. 697, t. 26, f. 11. 
 
 Receptaculites Neptuni (pars), D’Archiac and De Yerneuil, Trans. Geol. Soc., 
 1842, 2d ser., vi., pt. 2, p. 407. 
 
 ,, „ C. F. Roemer, das Rhein, Ubergangs. 1844, pp. 
 
 59, 60. 
 
 „ „ Bronn, Index Pal. Nomen., 1849, P- io 79 * 
 
 ,, „ Morris, Cat. Brit. Foss., 2d ed., 1854, p. 363. 
 
 I. Konigii , Salter, in Murchison’s Siluria, 4th ed., 1867, p. 509, t. 12, f. 4. 
 
 ,, „ Gray, Proc. Nat. Hist. Soc., Glasgow, 1868, i. 169. 
 
 ,, „ Bigsby, Thesaurus Sil., 1868, p. 3. 
 
 „ „ Salter, Cat. Camb., Sil. Foss., Woodwardian Mus., Cambg., 1873, 
 
 p. 100. 
 
 „ „ Armstrong, Young, and Robertson, Cat.W. Scot. Foss., 1876, p. 13. 
 
 Obs. — The Gray collection contains two specimens of Ischa- 
 dites , both fragmentary, and without the original integument 
 preserved. The larger of the two specimens is probably an 
 example of /. Konigii , whilst the second appears to us to have 
 areolae possessing more the characters of /. antiquus , Salter ; 
 it shows the top and the so-called aperture. Neither of the 
 
 1 Pal. of Niti, 1865, p. 48. 2 Pal. Fossils of Canada, i. 384. 
 
SA CCAMMINA. 
 
 2 1 
 
 specimens affords characters sufficient for description. Ischadites 
 was first indicated as a Girvan fossil by Mr R. Gray, F.R.S.E, 
 Loc. and Horizon. — Balcletchie, near Girvan, in a fine- 
 grained shale of Upper Silurian age. Penkill, in a fine green- 
 ish-coloured conglomerate, also of Upper Silurian age (smaller 
 specimen). Gray Coll. 
 
 Genus Saccammina, Sars. 
 
 (Vidensk.-Selsk, Forhandl., 1868.) 
 
 Saccammina Carteri, H. B. Brady. 
 
 (PI. IX. fig. 23.) 
 
 Saccammina Carteri , H. B. Brady, Ann. and Mag. Nat. Hist., ser. iv., vol. vii. 
 p. 177, PI. XII., 1871. Also, r in Monograph of the Carboniferous and 
 Permian Foraminifera, Pal. Soc., p. 57, PI. I., figs. 1-7, and PI. XII., fig. 
 6, 1876. 
 
 Having obtained from the “ Craighead Limestone,” at 
 Tramitchell, some small fossils which we believed to be re- 
 ferable to the above species, we submitted them to our friend 
 Henry B. Brady, Esq., F.R.S., one of the greatest of living 
 authorities upon the fossil and recent Foraminifera , and he 
 not only confirmed our determination, but kindly furnished us 
 with the subjoined notes upon this interesting form, as well as 
 upon the microscopical characters of the limestone in question. 
 The other Microzoon referred to by Mr Brady as probably 
 allied to the recent genus Hyperammina we have thought it 
 well to describe provisionally under the name of Girvanella 
 problematical a title which does not imply its absolute identity 
 with the living form : — 
 
 “ Of the specimens of limestone which I have examined 
 some are very dark-grey, others lighter coloured and brownish. 
 The polished surfaces of the latter often show blue-grey patches, 
 as though the brown tint were due to some alteration in chemi- 
 cal composition. The rough weathered surface of the stone is 
 studded with fossil remains of one sort or other, chiefly the 
 projecting fractured ends of the stems of encrinites ; but there 
 
22 
 
 RHIZOPODA. 
 
 are in addition certain rounded bodies varying in size from 
 i-20th to i - 8 th of an inch in longer diameter. These are 
 generally too much worn, and otherwise altered, to give any 
 satisfactory indications of their nature or origin ; but trans- 
 parent sections of the rock leave no sort of doubt that they 
 are segments of Saccammina Carteri , a well-known Carbon- 
 iferous Rhizopod. 
 
 “In the Carboniferous limestones Saccammina is sometimes 
 so abundant that the rock may fairly be said to be built up of 
 its remains : in other cases it is sparsely distributed, the seg- 
 ments are few and far apart, but individually they are of larger 
 size. At Elfhills, in Northumberland, where the fossil was 
 * originally discovered, both these conditions exist, a thin bed 
 near the surface being crowded with the fusiform segments ; 
 whilst in a much thicker bed, lower down in the series, they 
 are few and far between. 
 
 “ The Girvan limestones, such of them as I have seen, bear 
 considerable resemblance to the lower of these two formations ; 
 but the specimens of Saccammina, as indeed of all the fossils, 
 have undergone even more change in the process of mineral- 
 isation than is usual in the Carboniferous rocks. The cham- 
 bers are completely filled with crystalline carbonate of lime, 
 which has become so incorporated with the substance of the 
 shell-wall as to obliterate its principal structural features, so that 
 in transparent sections of the limestone, the segments often 
 appear only as colourless rounded patches, without any trace of 
 the original investment. At times the peripheral portions are 
 slightly denser, and less transparent, than the rest of the patch, 
 whilst an occasional specimen still shows the outline and thick- 
 ness of the shell-wall with comparative distinctness. So far as 
 can be observed, the Saccammina of the Girvan limestone 
 agrees precisely in size, form, and structure with that of the 
 Carboniferous beds. 
 
 “ Under the most favourable conditions it is not easy to 
 identify the Microzoa of compact sub-crystalline limestones ; 
 and from the fragments of minute fossils which appear in the 
 
GIRVANELLA . 
 
 23 
 
 sections of the Girvan rock there is scarcely anything to be 
 gathered. One organism, however, deserves a passing notice 
 from the frequency with which it is met with. It is found in 
 the form of little masses of thin, fine, arenaceous tubes — either 
 a continuous tube of nearly even diameter coiled irregularly on 
 itself, or possibly of more than one, intertwined. The masses 
 are exceedingly minute, and they are too obscure for detailed 
 description, but they are of interest in connection with certain 
 organisms of the genus Hyperammina recently obtained from 
 the deep-water dredgings of the Challenger expedition. One 
 of these, of which the description and figures are not yet pub- 
 lished ( H . vagans, Brady, MS.) often occurs in a condition very 
 similar to these little bodies, though usually of much larger 
 size. When quite perfect the recent species has a swollen 
 primordial chamber, but it is very rarely, indeed, that complete 
 specimens are met with. I know of no other organism, recent 
 or fossil, that these little masses of tubes so closely resemble.” 
 
 Genus Girvanella, Nich. and Eth., jun. Gen. nov. 
 
 Gen. char. — Microscopic tubuli, with arenaceous or calca- 
 reous (?) walls, flexuous or contorted, circular in section, form- 
 ing loosely compacted masses. The tubes apparently simple 
 cylinders, without perforations in their sides, and destitute of 
 internal partitions or other structures of a similar kind. 
 
 Obs . — We have founded the. above provisional genus for the 
 minute fossils alluded to above, to which, for convenience’ 
 sake, we shall attach the following specific title — 
 
 Girvanella problematica, Nich. and Eth., jun. Sp. nov. 
 
 (PL IX., fig. 24.) 
 
 Spec. char. — Tubes from 1 -600th to 1- 700th of an inch in 
 diameter, not observed to taper, twisted together in loosely 
 reticulate or vermiculate aggregations of a rounded or irregular 
 shape, which seem to be mostly from i-20th to i-ioth of an 
 inch across. 
 
24 
 
 RHIZOPODA. 
 
 Obs . — Minute bodies having the above structure are very 
 abundant in the “ Craighead Limestone ” in certain beds, and 
 seem to deserve notice and a name. Their presence can some- 
 times be recognised by the naked eye, in the form of small 
 irregular patches of a brownish or greyish colour ; but we have 
 only been able to examine them by means of transparent slices 
 of the stone, and we know nothing of their external characters. 
 Microscopic examination shows them to consist of small de- 
 tached aggregates of twisted or flexuous cylindrical tubes, 
 which are clearly hollow, and are presented to us with such a 
 variable section as to show that they were irregularly contorted. 
 Many are cut right across, and show only the divided ends of 
 the tubes ; others are shown in short lengths of varying extent. 
 Here and there two or three tubes run side by side, but they 
 unquestionably were independent of each other, never actually 
 attached by their walls ; and they are always so loosely reticu- 
 lated together that the interstices of the mass are filled up 
 with transparent calcite, readily distinguishable from the more 
 opaque and granular matrix which surrounds them. 
 
 As to the affinities of these curious bodies we are inclined to 
 regard them as Rhizopods. Our friend John Murray, Esq., 
 suggested to us that they might possibly be of the same nature 
 as certain Rhizopod-tubes obtained by the Challenger Expe- 
 dition, and about to be described by Mr H. B. Brady under 
 the name of Rhizammina algceformis ; and they certainly have 
 a curious resemblance to these. The last-named authority, 
 however, as before stated, thinks that they are more nearly 
 allied to forms like Hyperammina vagans “ with an unlimited 
 length of fine, thin, arenaceous tube, which curls, twists, coils, 
 and plaits itself in every conceivable way” (H. B. Brady, in a 
 letter to the authors). 
 
 Form, and Loc . — Very abundant in parts of the “ Craighead 
 Limestone,” at Tramitchell, near Girvan. ( Coll ., H. A. 
 
 Nicholson. 
 
LYOPORA. 
 
 2 5 
 
 SUB-KINGDOM CCELENTERATA. 
 
 CLASS ACTINOZOA. 
 
 Genus Lyopora, Nich. and Eth., jun. Gen. nov. 
 
 Gen. char. — Corallum composite, massive, composed of 
 tubular, sub-cylindrical, or hexagonal corallites, which are more 
 or less completely fused with one another. Walls of the coral- 
 lites extraordinarily thick and dense, destitute of mural pores. 
 Columella absent. Septa rudimentary, few in number, having 
 the form of irregular obtuse ridges on the interior of the wall. 
 Tabulae complete. No coenenchyma. 
 
 Obs. — We have found ourselves compelled to establish the 
 new genus Lyopora for the reception of the very singular corals 
 described by Prof. M‘Coy under the name of Palceopora (?) 
 favosct (Ann. and Mag. Nat. Hist., ser. 2, vol. vi. p. 285), the 
 same name being subsequently given to it, without the note of 
 interrogation (Brit. Pal. Foss., p. 15). In both the descriptions 
 quoted, M‘Coy expresses the opinion that this coral should 
 probably be regarded as a new genus, and this surmise we are 
 fully able to sustain. The reference of the coral under consid- 
 eration to the genus Palceopora , M‘Coy { — Hello lit es), was the 
 result of a reliance upon appearances which are wholly illusory, 
 its affinities with Heliolites being of the slightest possible char- 
 acter. The total absence of “ ccenenchymal tubuli,” as con- 
 clusively demonstrated by thin sections, is sufficient proof of 
 this, and M ‘Coy's belief in the existence of such tubules 
 appears to be really based only upon the occasional existence 
 of small interspaces, of an entirely irregular character, at the 
 angles of junction of the corallites, or sometimes in the sub- 
 stance of the thick walls of these tubes. Microscopic examin- 
 ation also renders it quite certain that M‘Coy was in error in 
 supposing that a columella was present, no traces of such a 
 structure existing. He does not state specifically whether he 
 
26 
 
 ACTINOZOA . 
 
 had observed this organ in specimens preserved in the lime- 
 stone ; but we should be disposed to think that his belief in 
 the occurrence of a columella was really based upon the bodies 
 which he describes as the casts in sandstone of Palceopora 
 favosa ; these bodies in reality being (as noted by Salter, Quart. 
 Jour. Geol. Soc., vol. vii., p. 174) unquestionably casts of the 
 singular Nidztlites favus , and having, therefore, no connection 
 with the present form. 
 
 In superficial aspect, as remarked by M‘Coy, the corals of 
 this genus closely resemble Favosites ; but they are fundamen- 
 tally distinguished therefrom by the immense thickness of the 
 wall, the absence of mural pores, and the presence of rudimen- 
 tary septa. The genus, in fact, is apparently most closely allied 
 to those forms of Columnaria , Goldfuss (as this is usually 
 understood), in which the septa are imperfect and marginal ; 
 but it is sufficiently separated by the enormous development 
 of the walls of the corallites, the comparative irregularity of 
 these tubes, and the more incomplete condition of the septa. 
 
 The only other genus with which the present could be con- 
 founded, and the resemblance between the two is very remote, is 
 Pachypora , Lindstrom. In the latter, however, apart altogether 
 from differences of size, form, and mode of growth, the thick- 
 ening of the walls of the corallites is by the deposition of suc- 
 cessive concentric layers of carbonate of lime, and mural pores 
 are present. 
 
 Lyopora favosa, M‘Coy, sp. 
 
 (PI. II., figs. 1-1 e.) 
 
 Palaopora (?) favosa , M‘Coy, Ann. and Mag. Nat. Hist., ser. 2, vol. vi. p. 
 285, 1850. 
 
 „ favosa, M‘Coy, Brit. Pal. Foss., p. 15, PI. I. C, fig. 3, 1851. 
 Heliolites (. Palceopora ) favosus, Salter, Quart. Jour. Geol. Soc., vol. vii. p. 
 17°, 1851. 
 
 Spec . char. — Corallum composite, massive, spheroidal, hemi- 
 spheric, pyriform, or irregular in shape ; the corallites sub- 
 cylindrical, elliptical, hexagonal, or irregular in outline, firmly 
 
L YOPORA. 
 
 27 
 
 united with one another. Calices usually circular or hexagonal, 
 averaging a line and a half in diameter, the lip coarsely gran- 
 ular. Walls imperforate, extraordinarily thick, the interspaces 
 between any two contiguous calices being occupied by dense 
 calcareous tissue, of from three-quarters of a line to more than 
 a line in thickness, sometimes with minute and entirely irregular 
 vacuities. Septa rudimentary, often wanting in individual cal- 
 ices, varying in number from two or three up to ten or twelve 
 or more, always abortive, and represented only by rough and 
 blunt ridges on the interior of the wall. Visceral chamber 
 crossed by strong, solid, complete tabulae, distant from a line to 
 a line and a quarter from one another. 
 
 Obs . — In their great work on British Fossil Corals, Milne- 
 Edwards and Haime express the opinion that this species is 
 really founded upon ill-preserved specimens of Heliolites inter- 
 stincta, Wahl. (Brit. Foss. Corals, p. 250). It should be 
 remembered, however, that this opinion was not based upon 
 any inspection of actual specimens, and that it was to a large 
 extent justified by the very misleading figures of the internal 
 structure of the species given by M‘Coy (Brit. Pal. Foss., PI. 
 I. C, figs. 3 a and 3 b). 1 On the other hand, the careful examin- 
 ation of a large number of specimens, both macroscopically and 
 by means of microscopic sections, has thoroughly satisfied us 
 not only of the validity of the species, but also of its belonging 
 to a special generic type. So great, indeed, are the discrep- 
 ancies in the respective observations of M‘Coy and ourselves 
 as to the structure of this coral, that we were at first disposed 
 to think that we must be in error in supposing that our form 
 was that originally described as Palczopora (?) favosa . M‘Coy, 
 
 however, only gives two localities for his fossil — viz., in the 
 limestone of Craighead, near Girvan, where it is said to 
 be “ extremely abundant,” and in the sandstone of Mulloch 
 Quarry, where it is said to occur in the state of casts. The 
 
 1 These figures have similarly misled Lindstrom, who, in a list of Silurian Corals 
 from Sweden (Ofversigt. af Kongl. Vetenskaps Akad. Forhandl., 1873), describes a 
 Heliolites under the name of Heliolithes favosus , M‘Coy. 
 
28 
 
 ACTINOZOA. 
 
 supposed casts of the latter locality are undoubtedly referable 
 to Nidulites favus , so that we have only the specimens from 
 the limestone to deal with ; and as the form which we consider 
 to be P 'a Ice op ora (?) favosa , M‘Coy, not only occurs abundantly 
 at Craighead, but is the only coral which could possibly be 
 supposed to agree with M‘ Coy’s description and figures, we 
 cannot doubt the identity of the two. 
 
 As regards its general form, Lyopora favosa appears to be 
 very variable, but it occurs most commonly as pyriform or sub- 
 hemispheric masses (PI. II., fig. i), which are rooted at one 
 point, and seem to have the whole of the rest of the surface 
 covered with the calices, the corallites thus diverging from a 
 basal point or from a median line. No epitheca seems to have 
 existed. The size of ordinary specimens varies from an inch 
 or less in height and breadth up to half a foot or more. The 
 calices are rarely well preserved, but even in worn examples 
 their margins are rendered tubercular by the rudimentary septa. 
 The most conspicuous feature in the minute structure of the 
 species is certainly the great thickness of the walls of the cor- 
 allites, as shown both in tangential and vertical sections. 
 Microscopic examination of such sections (PL II., figs, i b - 1 e) 
 conclusively proves the total absence of both “ mural pores ” 
 and “ ccenenchymal tubules,” and the figures of the latter given 
 by M‘Coy (loc. cit .) cannot, therefore, be accepted as otherwise 
 than apocryphal. The calcareous walls of the corallites (PI. II., 
 fig. i e) are in fact quite compact, usually fused completely with 
 one another, or sometimes allowing the junction between con- 
 tiguous tubes to be detected, and occasionally showing minute 
 irregular spaces, which are undoubtedly only due to imperfect 
 deposition of the sclerenchyma. The tabulae are remote, 
 approximately horizontal, and unusually thick ; and though 
 best seen, of course, in vertical sections, they are often dis- 
 played in portions of tangential sections, either owing to the 
 plane of the section cutting some of the corallites obliquely, or 
 to its absolutely coinciding with the plane of a tabula. Lastly, 
 the septa (PL II., i a and i e) vary much in number, appearing 
 
TETRADIUM. 
 
 29 
 
 most commonly to be from ten to fifteen, but they are always 
 mere blunt inward projections of the wall. 
 
 Form, and Loc. — Abundant in the limestone and calcareous 
 shales (Lower Silurian) of Craighead, near Girvan. (Coll., Mrs 
 R. Gray and H. A. Nicholson.) 
 
 Genus Tetradium, Dana, 1846. 
 
 (Wilkes’s Expl. Exped. Zoophytes, p. 701.) 
 
 Gen. char. — Corallum massive, sub-hemispheric or irregular 
 in form, composed of long prismatic corallites, in close contact, 
 but not amalgamated by their walls, and not arranged in super- 
 imposed strata in the typical forms. No mural pores; septa 
 distinct, few in number, typically four, short, not reaching the 
 centre of the visceral chamber, seeming as if formed by in- 
 flections of the wall. Calices generally petaloid, as are the 
 corallites in transverse section. Tabulae numerous, complete. 
 Increase by fission of the old tubes. 
 
 Obs. — The genus Tetradium is a small and peculiar one, 
 which, as we have elsewhere suggested (Ann. Nat. Hist., ser. 
 4, vol. xx., p. 163), may perhaps be placed in the neighbour- 
 hood of Halysites , though it has certain resemblances to Chce- 
 tetes. It is easily recognised, in typical examples, by the pecu- 
 liar shape of the long imperforate tubular corallites, which, in 
 transverse section, appear to be petaloid, owing to the presence 
 of generally four or five short septa, formed by inflections of 
 the wall. The accompanying engraving (fig. 2) shows the 
 minute structure of the corals of this genus, as displayed in 
 transverse and vertical sections. 
 
 Though common in the Lower Silurian of North America, 
 the genus Tetradium was not recognised as occurring in 
 Britain, till we pointed out (loc. jam cit.) that a peculiar form 
 belonging to it was present in pebbles of Silurian limestone 
 contained in the Old Red conglomerates of Habbie’s Howe, 
 in the Pentland Hills, near Edinburgh. These pebbles are 
 
3 ° 
 
 4 CTINOZOA. 
 
 peculiar in being often composed of a coarsely oolitic lime- 
 stone ; and at the time that we described the form of Tetradium 
 in question, we were unable to point to any limestone of sim- 
 ilar characters as occurring in place in the Silurian series of 
 
 t, 
 
 e 
 
 Fig. 2. — a, A small portion of a transverse section of Tetradium minus , magnified about ten 
 diameters. The section is a transparent one ; and the visceral chambers of the corallites, 
 being filled up with the matrix, appear black, whilst the walls are composed of crystalline 
 calcite ; in the centre of the section is a vacant space filled with calcite (a water-canal ?). 
 b, Portion of polished transverse section of same, not so highly magnified ; in this section 
 the visceral chambers appear as light spaces, and the walls are dark, c, Portion of a 
 longitudinal section of the same, showing tabulae, d, Portion of a transparent transverse 
 section of Tetradium Peachii , Nich. and Eth., jun., magnified about twenty diameters. 
 Near the bottom of the section a water-canal (?) is seen cut across, e , Portion of trans- 
 verse section of the same, magnified still further, f Portion of the longitudinal section 
 of the same, magnified about fifteen diameters, g, Portion of the same, enlarged still 
 further. 
 
 Scotland. Since then, however, we have found that a similar 
 oolitic limestone, of Silurian age, is developed in at least two 
 localities near Girvan — viz., plentifully at Tramitchell, and to a 
 less extent at Craighead ; and we have further had the satisfac- 
 tion of finding that the limestone at the latter place is largely 
 made up of masses of the same Tetradium ( T. Peachii ) as that 
 of the pebbles of the Habbie’s Howe conglomerate. We can 
 hardly doubt, therefore, that these pebbles were derived origi- 
 nally from the existing Craighead limestone of Girvan, or from 
 some former extension of this bed. 
 
TETRADIUM. 
 
 3 l 
 
 Tetradium Peachii, Nich. and Eth., jun. 
 
 (PI. I., fig. 3, and PI. II., figs, i-i b.) 
 
 Alveolites (?), sp., R. Eth., jun., Proc. Roy. Phys. Soc. Edinb., 1874-75, p. 51. 
 
 „ (?), Peachii , R. Eth., jun. (MS.), Coll. Geol. Survey of Scotland, Mus. 
 
 Science and Art, Edinb. 
 
 Tetradium Peachii , Nich. and R. Eth., jun., Ann. and Mag. Nat. Hist., ser. 4, 
 vol. xx. p. 166. 
 
 Spec. char. — Corallum massive, very irregular in shape, 
 often more or less lobulate on the surface, composed of 
 excessively minute, closely approximated corallites, from 
 1 -25th to 1 -35th of a line in diameter. The corallites 
 are amalgamated by their comparatively thick walls, ir- 
 regularly circular or oval in outline, running parallel with 
 one another in straight, slightly curved, or undulating lines. 
 Very often the corallum consists of successive layers of coral- 
 lites disposed in a concentric manner round one or more 
 centres. Septa generally present, mostly three or four in 
 number, short, looking as if formed by an inflection of the 
 wall of the corallite, to the transverse section of which they 
 communicate a petaloid aspect. Tabulae usually numerous 
 and complete. 
 
 Obs . — As before remarked, this singular form is extremely 
 abundant in the Silurian limestone of Craighead, near Girvan, 
 and the specimens from this locality are in a much better con- 
 dition for microscopic examination than those from the pebbles 
 in the Habbie’s Howe conglomerate. We are therefore now 
 able to confirm our former reference of the species to the genus 
 Tetradium , and we are in the position to describe some addi- 
 tional points in its minute structure. As seen at Craighead, 
 Tetradium Peachii occurs both in the limestone and in its asso- 
 ciated shales, and presents itself in the form of wholly irreg- 
 ular masses, of very variable size. Small masses from the shale 
 range from three lines to an inch and a half in diameter, and 
 are generally more or less spheroidal or oval in shape. When 
 not obscured by matrix, the surface is often more or less con- 
 
32 
 
 ACTINOZOA. 
 
 spicuousty mammillated or botryoidal (PL I., fig. i 6 ), but in 
 no case have we succeeded in detecting the calices by a simple 
 examination of the weathered surface with a lens. Specimens 
 from the limestone rarely weather out to any extent, and 
 yield to fracture as if they formed part of the rock itself. 
 They form masses often two or three inches in diameter, which 
 are easily recognised by their whitish or light-brown colour, 
 and by their dense texture ; and which not uncommonly show 
 on broken surfaces an arrangement in concentric layers of 
 growth, similar to that observed in the specimens from the 
 Habbie’s Howe conglomerate, and reminding one of some of 
 the more compact forms of the Stromatoporoids. 
 
 Even in the Craighead specimens, the minute structure of 
 Tetradium Peachii can only be made out by transparent slices, 
 examined with the microscope. Transverse sections (PL I. 3), 
 when they are at all accurately at right angles to the corallites, 
 show that these possess the characteristic form of the tubes in 
 this genus. Extraordinarily minute as the corallites are — 
 generally about 300 in the space of an inch — they usually show 
 the characteristic petaloid form and the four short septa of 
 Tetradium. The septa, however, vary from one to five, and 
 in many of the corallites they can only be detected with diffi- 
 culty, apparently owing to the fact that the section does not 
 pass through the tubes at right angles to their long axis. In 
 long sections (PL II., figs. 1 and 1 a ), the corallites are seen to 
 generally possess more or less wavy walls, and to increase by 
 fission, and the chief new point that we have noticed is that 
 the tabulae are very variable in their occurrence. In the 
 Habbie’s Howe specimens the tabulae seem to be rarely want- 
 ing, and they are usually very numerous and close-set (see fig. 
 2, f and^). In the Craighead specimens tabulae of a similar 
 character are sometimes present (PL II., fig. 1) ; but they 
 may be only present in a portion of a mass, and in many sec- 
 tions (PL II., fig. 1 a) they cannot be detected at all. This, 
 however, is only in accordance with what we know commonly 
 to occur in Favosites and other similar forms, in which the 
 
TETRADIUM. 
 
 33 
 
 tabulae often seem to have been completely or partially de- 
 stroyed during fossilisation. Lastly, in many of the specimens 
 from Habbie’s Howe, we have noticed that the corallum is 
 perforated by irregular tubes, perhaps of the nature of water- 
 canals, varying from i-40th to i-50th of an inch in diameter; 
 but we have not detected similar structures in the examples 
 from Ayrshire. 
 
 The rediscovery of this peculiar coral at Girvan is a point of 
 particular interest. Whence the limestone blocks and pebbles 
 containing T. Peachii , contained in the Habbie’s Howe con- 
 glomerate, originated, was to us, as to all others who had 
 examined them either in situ or in the laboratory, an unsolved 
 problem; for on appealing to Professor Geikie, F.R.S., we found 
 that he was unacquainted with such a limestone at any other 
 locality known to him in Scotland. Although the abundant oc- 
 currence of T. Peachii in the Craighead limestone, accompanied 
 as it is at times by the well-marked oolitic structure so common 
 in some of the Pentland Hill pebbles, would justifiably lead 
 one to suppose that we had here met with the point of origin 
 of the pebbles in question, still this is not altogether borne 
 out by the other coral forms which accompany T. Peachii at the 
 latter locality. We here meet with, in the same blocks, such 
 forms as Haly sites ( H . catenularia , Linn. ?), Plasmopora (P. 
 petalliformis , Lonsd. ?), Favosites (2 or 3, sp.), one of the latter 
 very near F. Hisingeri , Ed. and H., Heliolites ( H ’. inter stincta, 
 Linn. ?). These corals have been very carefully examined by 
 one of the writers and Dr J. C. Purves, and although there 
 may be some little doubt as to the exact specific identifica- 
 tions arising from the mode of preservation of the specimens, 
 we have little hesitation in placing reliance on them. 
 
 Form, and Loc. — Very abundant in the limestone (Lower 
 Silurian) of Craighead, near Girvan. (Coll., Mrs R. Gray and 
 H. A. Nicholson.) Also in pebbles of limestone of Silurian 
 age contained in the Old Red Sandstone conglomerate of 
 Habbie’s Howe, Pentland Hills, near Edinburgh. (Coll., J. 
 Henderson, R. Etheridge, jun., and Geol. Surv. Scot.) 
 
 c 
 
A CTINOZOA. 
 
 34 
 
 Genus Favosites, Lamarck, 1816. 
 
 (Hist, des An. sans Vert., vol. ii. p. 204.) 
 
 Favosites Girvanensis, Nich. and Eth., jun., sp. nov. 
 
 (PI. I., figs. 2-2 c.) 
 
 Spec. char . — Corallum diminutive, discoidal or sub-hemi- 
 spheric in shape, with a flat or convex base, which is covered 
 by a concentrically wrinkled epitheca. Diameter varying from 
 half an inch to rather more than an inch, and the height from 
 three to eight lines. Corallites prismatic, thin-walled, three- to 
 six-sided, closely approximated, of unequal sizes, the average 
 tubes being from a third to a fourth of a line in diameter, 
 generally the latter, while the angles of junction of these are 
 filled in by much smaller tubes. Mural pores not detected. 
 Septa wholly absent. Tabulae, when preserved at all, few and 
 remote, distant from one another from one-third to one-half of 
 a line. Walls of the corallites in longitudinal sections more or 
 less undulated and wavy. 
 
 Obs . — This little Favosites occurs in plenty in the shales 
 associated with the limestone at Craighead, near Girvan ; and 
 from the fact that its tubes exhibit wavy margins in longitu- 
 dinal section, we were disposed at first to think that it might 
 possibly be the young form of Favosites aspera , D’Orb. After 
 examining and cutting some fifty specimens, however, we have 
 come to the conclusion that it is really quite distinct from this 
 form, and, indeed, from all other described species. We are 
 very reluctant to add a new species to the already numerous 
 and often imperfectly defined forms of Favosites , but the present 
 species has peculiarities which preclude our placing it under any 
 type known to us. That it is merely the young of some other 
 form, as we at first imagined, is sufficiently disproved by the 
 fact that of the large number of individuals known to us, no 
 one exceeds one and a quarter inch in diameter, while most are 
 considerably under the inch — no other larger form of the genus 
 
FA VO SITES. 
 
 35 
 
 Favosites being at present known to occur at all in the same 
 beds. We are therefore bound to accept it as an adult form. 
 Not only does its size become thus a specific character, but 
 its discoidal form and concaye base, with its concentrically 
 striated epitheca (PL I., figs. 2 and 2 a), are equally so. In 
 these last - mentioned features, Favosites Girvanensis agrees 
 with the associated Prasopoi'a Grayce , nobis, as well as with 
 small examples of Ckcetetes petropolitanns, Pand., to both of 
 which it presents a very close superficial resemblance. The 
 latter, however, does not occur at all (so far as we know) in the 
 Craighead limestone, and even if it did, is quite distinct in its 
 minute structure, the latter observation holding true of Praso- 
 pora also. As it occurs only in the shales associated with the 
 Craighead limestone, F. Girvanensis shares with all the forms 
 from this position the misfortune of almost never exhibiting 
 any distinct structural features until it is sectioned ; but its 
 characters can be readily determined by microscopic examina- 
 tion. That it is a true Favosites is, in our opinion, sufficiently 
 shown by the prismatic, thin - walled, closely - approximated 
 tubes, the total absence of ccenenchyma and of septa, and the 
 characters of the tabulae when present. That we should have 
 failed to detect mural pores does not invalidate this conclusion, 
 as these structures can rarely be detected except in specimens 
 showing the exterior of the tubes, and we possess none such. 
 Nor does the variable condition of the tabulae, and their 
 commonly-occurring total absence, materially affect our views, 
 since similar conditions are well known to obtain in apparently 
 similarly preserved specimens of the larger forms of this genus. 
 When present, however, the tabulae are characteristic, in their 
 comparatively small number, and the distance at which they 
 are placed from one another (PL I., fig. 2 b). In all cases, 
 also, the markedly wavy and undulated walls of the tubes (PL 
 I., fig. 2 c) are highly characteristic. The other points which 
 seem to us to adequately separate this form as a distinct species 
 are the diminutive size, the constant discoidal form, the con- 
 cave base, the concentrically wrinkled epitheca, the small size 
 
ACTINOZOA. 
 
 3 6 
 
 of the corallites, and the presence of minute prismatic tubes 
 intercalated between those of average size. 
 
 Form, and Loc . — Not uncommon in the shales associated 
 with the limestone at Craighead, near Girvan. (Coll., Mrs R. 
 Gray.) We have also a single specimen from the Gray collec- 
 tion, which is labelled as coming from Penkill, near Girvan, 
 the greenish mudstones of this locality being much higher in 
 the Silurian series than the Craighead limestone. 
 
 Favosites Mullochensis, Nich. and Eth., jun., sp. nov. 
 
 (PI. II., figs. 2-2 b.) 
 
 Spec, char . — Corallum small, forming ovoid or hemispherical 
 masses, from half an inch to an inch in diameter. Corallites 
 more or less pentagonal, with very thin wavy walls. The 
 majority of the tubes large, from half a line to nearly a line in 
 diameter, but having wedged in between them a few much 
 smaller tubes. Mural pores apparently few and remote, not 
 serially disposed. Septa wanting. Tabulae few, very deli- 
 cate, remote, from half a line to a line apart, generally repre- 
 sented only by short spines springing from the undulated walls 
 of the tubes. 
 
 Obs . — This appears to be a genuine Favosites, though in 
 some respects an abnormal one. We possessed only three 
 specimens to work with, and in all of these, owing to the great 
 thinness of the walls of the corallites, the internal structure had 
 been to some extent obscured by fractures taking place during 
 fossilisation, while in all the specimens the tubes had been 
 largely filled up with the matrix, and were only infiltrated with 
 calcite in their centre. When viewed in transverse section 
 (PI. II., fig. 2 a) the corallites are seen to be mostly of large 
 size, though here and there a very small tube is intercalated 
 between the others. The tubes are not strictly rectilinear, as 
 in the most typical species of Favosites, but the walls are 
 usually more or less curved, and often at places sharply bent 
 and wrinkled — this latter feature perhaps due to changes 
 
FA VO SITES. 
 
 37 
 
 taking place showing mineralisation. In the only specimen in 
 which we could detect mural pores, these openings are few, 
 large-sized, and irregular in distribution. The most character- 
 istic features of the species are seen in longitudinal sections 
 (PL II., 2 b), and are displayed by all our specimens. These 
 features are, — firstly, the fact that the walls of the tubes are 
 conspicuously undulated ; secondly, the presence of a very few 
 extremely thin tabulae ; and thirdly, the fact that the majority 
 of tabulae are represented by short spines springing from the 
 walls. 
 
 Foinn. and Loc . — In the dark-green mudstone (Upper Silu- 
 rian) of Mulloch Hill. {Coll., Mrs R. Gray.) 
 
 Favosites Gothlandica, Lamarck. 
 
 Favosites Gothlandica, Lamarck, Hist, des An. sans Vert., vol. ii. p. 206, 1816. 
 
 Ccilamopora Gothlandica , Goldfuss, Petref. Germ., PI. XXVI., figs. 3 a, 3 b, 
 3 c, 3 e (caet. exclusis), 1829. 
 
 Favosites sub-basa/tica, D’Orbigny, Prodr. de Paleont., vol. i. p. 49, 1850. 
 
 „ Gothlandica , M‘Coy, Brit. Pal. Foss., p. 20, 1851. 
 
 „ Goldfussi , D’Orbigny, Prodr. de Paleont, vol. i. p. 107, 1850. 
 
 „ Goldfussi , Milne-Edwards and Haime, Pol. Foss, des Terr. Pal., 
 
 p. 235, PI. XX., fig. 3, 1851. 
 
 ,, Gothlandica , Milne-Edwards and Haime, Brit. Foss. Cor., p. 256, 
 1854. 
 
 „ Niagarensis , Hall, Pal. N.Y., vol. ii., PI. XXXIV. A, bis, fig. 4, 1851. 
 
 „ Gothlandica , Billings, Can. Journ., new ser., vol. iv. p. 99, 1859. 
 
 ,, Gothlandica , Nicholson, Report on the Palaeontology of Ontario, 
 
 ^ 74 , P- 45 - 
 
 (For a full synonymy of F. Gothlandica up to the year 1854, see Milne-Edwards 
 and Haime in Brit. Foss. Cor., p. 256.) 
 
 Obs. — So far as the specimens which we have personally 
 examined are concerned, the only undoubted examples of 
 Favosites Gothlandica , Lam., are some that were detected by 
 our friend Mr Charles Lap worth, F.G.S., in a limestone-band 
 on the shore near Girvan. They are well preserved, and are 
 in all respects identical with the typical examples of this species 
 from the Upper Silurian and Devonian; but as they present 
 no points of special interest, they need no further description 
 here. They are associated with the next species (which we 
 
38 
 
 4 CTINOZOA. 
 
 believe to be Alveolites Labechei), and with casts of a small 
 Pentamerus, and they are noteworthy as indicating the exist- 
 ence of a limestone near Girvan, of Llandovery or Wenlock 
 age. 
 
 Form, and Loc. — Common in a coralline limestone-band on 
 the sea-shore, not far from Shalloch Mill, near Girvan. (Coll., 
 Mr Charles Lapworth.) 
 
 Genus Alveolites, Lamarck, 1801. 
 
 (Syst. Anim. sans Vertebres., p. 375.) 
 
 Alveolites Labechei, Edw. and H. 
 
 Favosites spongites (pars), Lonsdale, in Murchison’s Sil. Syst., PI. XXV., bis, 
 figs. 8, 8 b (caet. exclusis), 1839. 
 
 Ccilamopora spongites , Eichwald, Sil. Syst. in Esthland, p. 197, 1840. (Not 
 Calamopora spongites of Goldfuss.) 
 
 Alveolites Labechei, Milne-Edwards and Haime, Pol. Foss, des Terr. Pal., 
 p. 275, 1851. 
 
 „ ,, Milne-Edwards and Haime, Brit. Foss. Cor., p. 262, 1854. 
 
 Obs. — The limestone-band which we have referred to in the 
 description of the previous species has yielded to the researches 
 of Mr Lapworth specimens of an Alveolites which we feel no 
 hesitation in identifying with A. Labechei, Edw. and Haime. 
 Our examples do not show any surface-characters, but micro- 
 scopic sections indicate that the internal structure is well pre- 
 served, and this is quite in accordance with that of specimens 
 of the well-known Wenlock form, so that it will be unneces- 
 sary to occupy any space here with a detailed description. 
 
 Form, and Loc. — In a band of coralline limestone on the sea- 
 shore, not far from Shalloch Mill, near Girvan. (Coll., Mr 
 C. Lapworth.) 
 
 Genus Fistulipora, M‘Coy, 1849. 
 
 (Ann. Nat. Hist., ser. 2, vol. iii. p. 130.) 
 
 Gen. char. — Corallum very variable in form, encrusting, 
 sub-massive, massive, or ramose, composite, of numerous com- 
 
FISTULIPORA. 
 
 39 
 
 paratively large-sized corallites surrounded by a very varying 
 number of smaller tubes (the latter corresponding to the 
 “ coenenchymal tubules,” so-called, of Heliolites and its allies). 
 Septa wanting. Tabulae well developed and complete, usually 
 more numerous in the smaller than the larger tubes. No 
 mural pores. Larger corallites typically circular, and usually 
 with slightly exsert calices. 
 
 Obs . — Though it is not possible at present to limit the 
 genus Fistulipora precisely, we may include under the above 
 emended definition a number of Palaeozoic corals, which for 
 the most part present unusual difficulties in the way of their 
 study. The superficial features of these forms — especially 
 the presence of large-sized circular corallites, usually with 
 slightly elevated calices, without septa, and surrounded by 
 smaller circular or angular tubes — are sufficiently distinct to 
 separate them readily from their allies, such as Chcetetes. 
 The absence of mural pores and of septa, and the presence of 
 complete tabulae in both sets of tubes, are the chief features 
 in their internal organisation. We have no personal know- 
 ledge of forms with funnel-shaped tabulae in the larger tubes 
 — a character to which generic importance is assigned by M‘Coy 
 — nor have we ever observed the tabulae to be confined to the 
 smaller tubes, and wholly wanting in the larger ones. 
 
 We cannot enter here into a discussion as to how far Fistu- 
 lipora, M‘Coy, covers the ground occupied by the later genus 
 Callopora , Hall (Pal. N.Y., vol. ii. p. 144, 1852). Our pres- 
 ent impression, however, is that the two are incapable of 
 separation, in which case M ‘Coy’s name must be retained. 
 Nor have we found it possible to accurately compare the 
 species of Fistulipora which we are about to define with the 
 very numerous forms of Fistulipora and Callopora which have 
 been described by American palaeontologists from Silurian and 
 Devonian strata. There exist, in fact, no sufficient elements 
 for such a comparison, since the American species are at pres- 
 ent mostly known only by short verbal descriptions, rarely 
 accompanied by figures, and for the most part without allusion 
 
40 
 
 4 CTIN0Z0A. 
 
 to the microscopic structure. Under these circumstances, we 
 are therefore compelled to describe the following species as 
 new. 
 
 Fistulipora favosa, Nich. and Eth., jun., sp. nov. 
 
 (PI. II, figs. 3-3 c.) 
 
 Spec. char . — Corallum sub-massive, composed of numerous 
 closely-approximated slender corallites, which diverge from an 
 expanded base of attachment. Calices very markedly of two 
 sizes, the larger ones circular or oval, and the smaller ones 
 more or less angular, the former varying from i -7th to i-6th of 
 a line in diameter, and the latter from i-i2th to i-6th of a line. 
 One or two rows of the smaller calices intervene between the 
 larger, the latter being thus separated from one another by 
 spaces varying from half their own width to the whole of their 
 width. Septa wholly wanting. Tabulae complete, strong, 
 straight or slightly curved, from four to eight in the space of 
 one line, generally fewer and more remote in the larger tubes 
 than in the smaller ones. Though the openings of the larger 
 corallites upon the surface are distinctly circular, all the tubes 
 appear to be angular in cross-sections taken a little below the 
 surface. 
 
 Obs . — The surface characters of this species are quite con- 
 clusive as to its being a true Fistulipora and not a Favosites 
 (see PI. II, fig. 3 a). The larger tubes, in fact, are always 
 filled up near the surface with the dark matrix, which passes 
 down to the first tabula, while the smaller and more closely 
 tabulate intervening tubes are infiltrated with calcite ; so that 
 there is a most conspicuous difference between the two sets of 
 tubes as examined at the surface. In thin sections, however, 
 this difference to a large extent disappears, and the structure 
 of the coral cannot readily be distinguished from that of a 
 Favosites ora Chcctetes. In transverse sections (PI. II, 3 < 5 ), 
 all the corallites are seen to be more or less angular, usually 
 pentagonal, and the larger tubes are with difficulty recognised, 
 
FIS. T UL I FOR A . 41 
 
 as they have lost their circular outline, and are usually infil- 
 trated with lime, thus agreeing with the intervening tubules. 
 A little care, however, will still distinguish the two sets of 
 tubes ; and the same distinction can also be carried out in long 
 sections (PL II., fig. 3 c), where the larger tubes are recog- 
 nised both by their comparative size and by their having fewer 
 and more remote tabulae than the smaller ones. 
 
 Upon the whole, Fistulipora favosa appears to be sufficiently 
 characterised by its sub-massive form ; the long corallites, not 
 superimposed in successive layers ; the round mouths of the 
 larger tubes, combined with their angular section at points 
 below the mouth ; the presence of one or two rows of smaller 
 angular tubes between the larger ones ; and the existence of 
 strong and complete tabulae in all the tubes, but most numer- 
 ously so in the small tubes. 
 
 The only individual of this species which we have examined 
 is an ovoid mass, with a comparatively expanded base of at- 
 tachment (PL II., fig. 3), its height being an inch and a half, 
 and its greatest width rather more than an inch. 
 
 Form . and Loc . — Dark-green ashy beds of Balcletchie, near 
 Girvan (? Lower Silurian). Gray collection. 
 
 Fistulipora (?) pilula, Nich. and Eth., jun., sp. nov. 
 
 (PI. III., figs. 1-1 b.) 
 
 Spec. char. — Corallum small, completely ovoid or- sub- 
 globular, from three to five lines in its longest diameter in 
 the specimens examined by us. Corallites radiating from a 
 central line and opening over the greater part of the surface, 
 of different sizes, but not clearly divisible into two sets of 
 different dimensions. Small tubes comparatively few, wedged 
 in at the angle of junction of the larger ones, angular in form, 
 the latter being rounded or sub-polygonal in section. The 
 larger tubes have an average diameter of about one-fifth of 
 a line, and the smaller ones are variable in size. Septa 
 absent. Tabulae numerous and close-set (12-15 in the space 
 
42 
 
 ACTINOZOA. 
 
 of a line) in the smaller tubes, but very few and remote in the 
 larger ones. 
 
 Obs . — As none of our examples show the characters of the 
 surface, we do not feel certain whether this is a Fistulipora , 
 or whether it should not rather be placed under Chcztetes ; 
 and the characters presented by the microscopic sections are 
 not conclusive upon this point. There is a great difference 
 between the sizes of the tubes which compose the corallum, 
 but it cannot be said that there is a series of large tubes 
 surrounded and separated by another series of small tubuli. 
 There is rather a series of large tubes, usually rounded or 
 slightly angular, partially separated but never completely 
 isolated by small angular tubes (PI. III., fig. i a). The 
 general aspect of cross-sections is certainly rather that of a 
 Fistulipora of the type of F favosa than of a true Chcztetes , 
 and longitudinal sections support this view. These (PL III., 
 fig. i b) show a series of large tubes, in which tabulae are 
 wholly wanting or very sparingly developed, separated by 
 much narrower tubes, in which tabulae are very numerous 
 and close-set. In no case do we find more than a single one 
 of the smaller tubes separating any two of the larger ones. 
 Increase is by fission of the old tubes. The only other char- 
 acters which distinguish the species are those founded upon 
 the small size of the corallum and its ovoid or globular shape ; 
 and these features seem to be constant, as eight individuals 
 examined by us have all the same figure, and the largest does 
 not exceed half an inch in diameter, the smallest being half the 
 size of this. 
 
 Form, and Loc . — In the shales associated with the limestone, 
 Craighead, near Girvan. (Gray collection.) 
 
CHsETETES. 
 
 43 
 
 Germs Cii^etetes, Fischer, 1837. 
 
 (Oryct. du Gouv. de Moscou, p. 159.) 
 
 Chsetetes, sp. 
 
 (PI. III., figs. 2-2 b.) 
 
 Obs . — The Craighead limestone has yielded various frag- 
 ments of a dendroid species of Chatties (or Monticuliporci) which 
 appears to be well characterised, and which we cannot identify 
 with any species of the genus known to us. We shall not, 
 however, assign a new specific title to this form, as it is quite 
 likely to prove identical with some already well-known species, 
 when all the latter have been subjected to microscopic exam- 
 ination. We shall therefore content ourselves with simply 
 appending a brief notice of the general characters and minute 
 structure of the present form : — 
 
 Corallum (PL III., fig. 2) dendroid, from one to two lines in 
 diameter, branching at short intervals. Calices sub-circular or 
 polygonal, nearly equal-sized, about i-6th or i~7th of a line in 
 diameter on an average, with here and there a much smaller 
 tube, but without minute interstitial tubuli. Surface destitute 
 of monticules. In cross-sections (PI. III., fig. 2 a) all the tubes 
 appear to be polygonal. In longitudinal sections (PL III., fig. 
 2 b) the tubes are seen to be vertical in the centre of the 
 branches, and to be here crossed by well-marked, straight, and 
 complete tabulae, of which about ten or twelve occupy the space 
 of one line. On approaching the surface, the tubes bend out- 
 wards, and widen somewhat, being crossed by curved and con- 
 siderably more closely arranged tabulae for some little distance 
 below their mouths. 
 
 Though of the same general type as various well-known 
 Silurian species (such as C. pulchellus , Edw. and H., and C. 
 Fletcheri , Edw. and H.), we cannot identify the form above 
 described with any previously recorded. The principal fea- 
 tures which separate it from its nearest allies are the approxi- 
 mate equality of the tubes, and their regularly tabulate charac- 
 
44 
 
 A CTINOZOA. 
 
 ter, together with the total absence of interstitial tubules, groups 
 of large-sized tubes, or “ monticules.” 
 
 Form, and Loc . — In the shales associated with the limestone, 
 Craighead, near Girvan. (Gray collection.) 
 
 Genus Prasopora, Nich. and R. Eth., jun., 1877. 
 
 (Ann. Nat. Hist., ser. 4, vol. xx. p. 38.) 
 
 Gen. char . — Corallum compound, forming small hemispheric 
 or concavo-convex masses, composed of numerous prismatic 
 corallites radiating from a wrinkled basal epitheca, and con- 
 nected by smaller coenenchymal tubules. Corallites with im- 
 perforate walls, destitute of septa, furnished with an exterior 
 zone of vesicular tabulae surrounding a vacant central tube, 
 which may be crossed here and there by an occasional tabula. 
 Calices showing a central aperture surrounded by a ring-like 
 tabula. Coenenchymal tubes much smaller than the corallites, 
 prismatic, usually arranged in a single zone round each coral- 
 lite, and crossed by numerous complete tabulae. Corallites and 
 coenenchymal tubes in contact with one another, but not sol- 
 dered together by their walls. 
 
 Obs . — The corallum in this genus is composite, and has the 
 general form and aspect of the massive species of Chcetetes 
 ( Monticulipora :). Its general shape (fig. 3, B) is concavo-con- 
 vex or hemispherical, the concave or flat base being covered 
 by a concentrically wrinkled and striated epithecal plate (fig. 
 3, A). From the centre of this the corallites radiate in all 
 directions, those in the middle of the corallum taking a nearly 
 vertical course, while those near the margins are horizontal, or 
 even deflexed, so as to run nearly parallel with the epitheca, 
 corallites holding an intermediate position between these two 
 points being bent at correspondingly intermediate angles. The 
 corallum is made up of comparatively large - sized corallites 
 interspersed with smaller “ coenenchymal ” tubules ; and the 
 structure of these two elements is very different internally. 
 
 The corallites, as shown by microscopic sections, have a 
 
PRASOPORA. 
 
 45 
 
 unique internal structure. In longitudinal sections (i.e., in sec- 
 tions parallel with their long axes) they are seen to be divided 
 into a central tube and an exterior tabulate area (fig. 3, D). 
 The central tube is either completely uninterrupted, or is occa- 
 sionally traversed by a delicate transverse tabula (perhaps at 
 intervals of a line or less), marking a temporary arrest in the 
 process of growth. In some cases the central tube is filled 
 with crystalline calcite ; but it is often more or less completely 
 occupied by an infilling of the surrounding matrix ; and there 
 are commonly little accumulations of the same material above 
 each of the transverse tabulae just alluded to. The central tube 
 is surrounded by a zone of tabulae which spring from the wall 
 of the corallite, and are then bent downwards so as to become 
 parallel to the long axis of the corallite, finally joining the 
 tabula next below. There is thus formed a series of large 
 circumferential vesicles, the convexities of which are directed 
 upwards and towards the centre of the corallite. When divided 
 fairly through the centre, the internal structure is seen to be as 
 above ; but when the section is excentric it passes through the 
 exterior tabulate zone, and the cut edges of the vesicular tabulae 
 appear as cross lines, looking like ordinary tabulae. As most 
 of the corallites are curved, an ordinary longitudinal section 
 divides them partly through the centre and partly excentrically, 
 so that part of the tube shows the one set of appearances and 
 part the other. 
 
 In order to examine the corallites in transverse section it is 
 necessary to cut a slice tangential to the upper surface (slices 
 cut tangential to the lower surface, owing to the deflection and 
 approximate horizontality of the marginal corallites, exhibit 
 oblique longitudinal sections of the tubes). In a properly pre- 
 pared transverse section (fig. 3, C), the corallites are seen to be 
 of a rounded or more generally hexagonal figure, with thick 
 and well-defined walls. In the centre of each is a rounded or 
 oval opening, representing the section of the central tube of the 
 corallite, filled either with calc-spar or with the dark matrix of 
 the enclosing rock. This opening is surrounded by one or 
 
4 6 
 
 A CTJNOZOA. 
 
 more curved lines, which are often tangents to the margin of 
 the central aperture, or are concentric to it, or intersect one 
 another. These lines are the cut edges of the tabulae which 
 form the exterior zone of each corallite, and they forcibly 
 remind one of the somewhat similar appearance presented by 
 
 Fig. 3 . A, Under surface of a small specimen of Prasopora Grayce, natural size, showing the 
 epitheca. 13, Side view of another, larger specimen, of the natural size. C, Transverse 
 section of the same, enlarged about twenty diameters. D, Longitudinal section, similarly 
 enlarged : #, One of the corallites ; b , One of the coenenchymal tubes. The dark shading 
 in the microscopic sections indicates where the matrix is present. 
 
 transverse sections of the corallites of Syringopora , with their 
 infundibuliform tabulae. The corallites, in fact, in transverse 
 section present a general resemblance to the bulb of an onion 
 when cut across ; and our generic name (Gr. prason , a leek) is 
 in allusion to this. The central tube of the corallites is about 
 one-third or often more of the total diameter ; and the walls of 
 the corallites are destitute of mural pores, and are not fused 
 with one another or with the tubes of the ccenenchyma. 
 
 The coenenchymal tubules are very variable in shape and 
 size ; but they are always much smaller than the true corallites, 
 and are mostly oblong, triangular, or trapezoidal in shape (fig. 
 3, C). They are wedged in amongst the corallites, round which 
 they are usually disposed in a single row ; but the zone thus 
 formed is rarely or never complete, each corallite coming into 
 contact at different points with one, two, three, or even four 
 contiguous ones. In some cases, also, there may be a double 
 row of coenenchymal tubes between the corallites. In internal 
 
PRASOPORA. 
 
 47 
 
 structure the tubes of the ccenenchyma possess none of the 
 special characters which distinguish the true corallites, longitu- 
 dinal sections showing them to be simply traversed by numer- 
 ous close-set, complete tabulae ( b , fig. 3, D), generally slightly 
 curved, with their convexities directed downwards. Transverse 
 sections also show them to want the central tube of the true 
 corallites, and to be irregular in form. Though we have 
 retained the name of “ ccenenchymal tubes ” for these, we think 
 it most probable that they are really of the nature of rudimen- 
 tary corallites, which contained in the living state a series of 
 small and specially modified zooids. 
 
 There are no traces of septa or of radial internal processes 
 of any kind, either in the ordinary corallites or in the ccenen- 
 chymal tubes of Prasopora. 
 
 Affinities. — The only forms with which it is necessary to 
 compare Prasopora are — (1) Chcetetes and Monticulipora ; (2) 
 Fistulipora and Callopora ; and (3) Heliolites and its allies. 
 
 The general appearance of the corallum in Prasopora , as 
 before remarked, is very closely similar to that of massive 
 examples of Chcetetes , Fischer, and Monticulipora , D’Orb. 
 From the forms included under these names, however, our 
 genus is widely removed by the possession of a well-developed 
 series of coenenchymal tubules (very different in character from 
 the minute tubuli found in many species of the two former 
 groups), and by the internal structure of the corallites. No 
 species of Chcetetes or Monticulipora , so far as we know, 
 exhibits anything to be compared with the external zone of 
 vesicular tabulae and the central tube of the corallites of 
 Prasopora. 
 
 To Fistulipora , M‘Coy, and the closely-allied or identical 
 Callopora , Flail, the present genus is related by the fact that 
 the corallites are surrounded by a greater or smaller number of 
 coenenchymal tubules. The two former, however, have the 
 tubes of the corallites simply intersected by numerous complete 
 tabulae (said to be absent in some species of Callopora) ; and 
 neither of them presents any approach to the peculiar structure 
 
ACTINOZOA. 
 
 48 
 
 of the corallites of Prasopora , though it is in their neighbour- 
 hood that we may at present place the last-named genus. 
 
 Lastly, Prasopora resembles Heliolites and its allies in the 
 fact that the corallites are surrounded by numerous transversely 
 tabulate coenenchymal tubules ; but the total absence of septa 
 and the peculiar structure of the corallites fundamentally sep- 
 arate the former from any member of the Helioporidse. We 
 may just add that the corallites of Prasopora in structure closely 
 resemble those of Roemeria (the true Calampora of Goldfuss), 
 but our genus is at once distinguished from this by the posses- 
 sion of “ coenenchymal tubules.” 
 
 Prasopora Grayae, Nich. and Eth., jun. 
 
 Spec. char . — Corallum forming small hemispheric or concavo- 
 convex masses, generally from half an inch to three-quarters 
 of an inch in diameter, and from a quarter to half an inch in 
 height. Corallites more or less prismatic, from five to six in 
 the space of one line (counting-in the intervening coenenchymal 
 tubules as well), thus averaging about i-yoth to i-8oth of an 
 inch in diameter. Coenenchymal tubules exceedingly variable 
 in size and form, but rarely equal to half the diameter of the 
 corallites. Epitheca and internal structure as described in 
 the generic characters. 
 
 Obs . — Though we have now carefully examined considerably 
 over a hundred specimens of this exceedingly interesting coral, 
 we have nothing to add to the above description, as originally 
 given by us. In both superficial characters and internal struc- 
 ture it appears to be extremely constant, and even its size varies 
 very little. Out of the large series in Mrs Gray’s collection 
 the smallest example that has come under our notice is three 
 and a half lines in diameter, and two and a half lines in height, 
 while the largest is thirteen lines across, and six lines in height. 
 
 For7n. and Loc . — Common in the shales associated with the 
 limestone at Craighead, near Girvan. (Gray collection.) 
 
HAL Y SITES. 
 
 49 
 
 Genus Halysites, Fischer, 1813. 
 
 (Zoognosia, 3d ed., vol. i. p. 387.) 
 
 Halysites catenulata, Linn. 
 
 Tubipora catenularia , Linne, Syst. Nat., ed. xii., p. 1270, 1767. 
 
 „ catenulata, Gmelin, Linne. Syst. Nat., ed. xiii., p. 3753, 1789. 
 
 Catenipora escharoides, Lamarck, Hist, des An. sans Vert., vol. ii. p. 207, 
 1816. 
 
 „ tubulosa and C. escharoides , Lamouroux, Exp. Me'th., p. 65, 1821. 
 
 „ labyrinthica and C. escharoides , Goldfuss, Petref. Germ., vol. i. pp. 
 74 and 75, 1826. 
 
 Halysites attenuata , Fischer von Waldheim, Note sur des Tubip. Foss., p. 16, 
 1828. 
 
 Catenipora approximata, Eichwald, Zool. Spec., vol. i. p. 192, 1829. 
 
 Halysites escharoides , De Blainville, Diet. Sc. Nat. Atlas, PI. XLIII., fig. 5, 
 1830. 
 
 „ labyrinthica and H escharoides , Bronn, Lethaea Geognostica, vol. 
 i. p. 52, 1835. 
 
 Catenipora labyrinthica , Milne-Edwards, in 2d ed. of Lamarck’s Hist, des An. 
 sans Vert. vol. ii. p. 322, 1836. . 
 
 ,, escharoides , Lonsdale, in Murchison’s Silurian System, p. 685, 
 
 1839. 
 
 Halysites catenularia , Milne-Edwards and Jules Haime, Pol. Foss, des Terr. 
 Pal., p. 281, 185 1. 
 
 „ catenulatus , M‘Coy, Brit. Pal. Foss., p. 26, 1851. 
 
 Catenipora escharoides , Hall, Pal. N.Y., vol. ii. pp. 44 and 127, 1852. 
 
 Halysites catenularia and H. escharoides , Milne-Edwards and Jules Haime, 
 Brit. Foss. Cor., pp. 270 and 272, 1854. 
 
 (The above list comprises some of the most important references to this well- 
 known coral. For a full synonymy up to date, see Milne-Edwards and Haime, 
 Brit. Foss. Cor., pp. 270 and 272.) 
 
 Form, and Loc. — In cement-stones at Shalloch Mill, near 
 Girvan, associated with Dicellograptus Moffatensis and other 
 Lower Silurian (Caradoc ?) forms. (Col/., Charles Lap worth.) 
 As our specimens show no points of special interest, we have 
 not thought it necessary to describe this familiar species. We 
 have also a single specimen of the same from the greenish 
 mudstones of Penkill, near Girvan, of Upper Silurian age. 
 (Gray collection.) 
 
 D 
 
5 ° 
 
 ACTINOZOA. 
 
 Germs Thecostegites, Milne-Edwards and Haime, 1849. 
 
 (Compt. Rend., t. xxix. p. 261.) 
 
 Thecostegites (?) Scoticus, Nich. and Eth., jun., sp. nov. 
 
 (PL IV, figs. 1-1 b.) 
 
 Spec. char. — Corallum composite, forming small masses, 
 apparently not encrusting, composed of short cylindrical coral- 
 lites, which diverge from the median line to open on the surface. 
 The corallites are sometimes partially free, at other times in 
 contact, but they widen out towards their mouths, where they 
 are united by a continuous calcareous expansion, in which the 
 calices are perforated. Calices mostly about half a line in 
 diameter, but varying from to ^ of a line, distant from one 
 another from ^ to ^ line, usually circular or oval, with slightly 
 elevated lips, and furnished with a variable number of extremely 
 short inward projections representing septa. Strong curved or 
 flexuous tabulae intersect the tubes at distances of from half a 
 line to a line. 
 
 Obs. — The genus Thecostegites, Edw. and H., is only known 
 by Devonian species ; and it is defined by its authors as pos- 
 sessing a sub-massive encrusting corallum, with short cylindrical 
 corallites, which are united by strong mural expansions, and 
 are only free in the interspaces between these, the calices being 
 circular, with rudimentary septa, and the tubes being crossed 
 by horizontal tabulae. 
 
 In Mrs R. Gray’s collection we find two small specimens 
 from the limestone at Craighead, which we are disposed to 
 place provisionally in this genus ; though it must be admitted 
 that they do not agree in some important respects with the 
 definition of Thecostegites above given, while the type has 
 not previously been recognised in rocks of such ancient date. 
 Our material, though well preserved as far as it goes, consists 
 only of two small and imperfect specimens, the largest not an 
 inch in length ; and they do not exhibit the mural expansions 
 which are said by Milne-Edwards and Haime to unite the 
 
THE COSTEGJTES . 
 
 5i 
 
 corallites, in places at any rate, in the genus Thecostcgites . On 
 
 the contrary, they are seen in longitudinal sections (PI. IV., fig. 
 1 b ) to have the walls of the corallites usually in contact. In 
 places, on the other hand, the corallites are certainly not in con- 
 tact, though it does not appear that they are here connected by 
 epi thecal outgrowths. However this may be, our form agrees 
 with Thecostcgites in the following points, which appear to us to 
 be sufficiently weighty to justify our referring it to this genus 
 as, at any rate, a provisional arrangement: (1.) The charac- 
 ters presented by the surface are very similar to those of The- 
 costegites Bouchardi (Pol. Foss, des Terr. Pal., PI. XIV., fig. 
 1 a). Thus, the calices are slightly elevated, and are seen to 
 rise from a continuous calcareous expansion, which separates 
 them to a comparatively considerable distance (PI. IV. > % O- 
 So far as we can make out, the calcareous expansion in which 
 the calices are pierced is formed by a thickening and coal- 
 escence of the corallites near their mouths ; but our observa- 
 tions on this point are not decisive. (2.) Rudimentary septa 
 are present. These can only be seen in microscopic sections 
 transverse to the corallites ; and they only exist as very short 
 blunt inward projections, of variable number (PI. IV., fig. 1 a). 
 (3.) Strong and remote tabulae intersect the corallites, though 
 in our form these are oftener curved than straight (PL IV., fig. 
 
 1 b). (4.) Growth is by lateral gemmation, as clearly shown in 
 
 long sections. (5.) Our species reminds us in many respects 
 of an Auloporo , though wholly different in internal structure, 
 and the same resemblance exists between the latter and one 
 of the forms of Thecostegites described by Milne-Edwards and 
 Haime (viz., T. auloporoides'). 
 
 Should our reference of the Craighead specimens to the 
 genus Thecostegites be confirmed by subsequent researches, we 
 cannot doubt their entire distinctness from the species of this 
 genus already known, and we have therefore given them a 
 specific title. If finally established, the occurrence of the genus 
 in rocks of Lower Silurian age will be a point of considerable 
 interest. 
 
5 2 
 
 ACTINOZOA. 
 
 Form, and Loc . — Rare in the shales associated with the 
 limestone at Craighead, near Girvan. (Coll., Mrs R. Gray). 
 
 Genus Pinacopora, Nich. and Eth., jun., gen. nov. 
 
 Gen. char . — Corallum composite, coin-shaped, of extremely 
 short corallites supported upon the upper convex surface of a 
 free, discoidal, concavo-convex, concentrically-striated epitheca. 
 Corallites of two sizes, regularly alternating with one another. 
 Large-sized corallites disposed in obliquely decussating rows, 
 each completely surrounded by a circle of very much smaller 
 corallites (“ coenenchymal tubes”), rarely more than a single 
 row of these latter, however, intervening between any given 
 pair of the larger tubes. Large tubes furnished with twelve 
 short septa, in the form of blunt spiniform projections ; small 
 tubes without septa. Large tubes furnished with one or two 
 tabulae, or rarely more, situated close to their base, the upper 
 portion of the tube being open. Small tubes furnished with 
 from two to four strong and complete tabulae, which extend 
 to close to their summits. Large tubes oval or circular in 
 form; small tubes irregular in shape. No mural pores. No 
 columella. 
 
 Obs . — The characters of this extraordinary genus are so 
 peculiar that we shall consider them at some length, — a method 
 of procedure which will enable us to dispense with more than 
 a very brief notice of the single species upon which it is estab- 
 lished. The specimens upon which we have founded the genus 
 Pinacopora are only known to us as occurring in a single 
 locality — viz., in the greenish mudstones of Mulloch Hill, 
 of Upper Silurian age; and we possess an extensive series 
 of these, from which we have been able to make out its 
 structure in almost every particular. The corallum is com- 
 pound and free, and has the form of a thin circular expansion, 
 the under surface of which is covered with a thin, wrinkled, 
 and concentrically-striated calcareous epitheca (PI. III., fig. 3), 
 which in nature and character entirely resembles the same 
 
riNACOPORA. 
 
 53 
 
 structure in such corals as Chcetetcs petropolitamis, Prasopora 
 Grayce , and other forms belonging to different types. The 
 epitheca is always symmetrically concave, and its upper convex 
 surface carries the corallites, which are remarkable for their 
 extreme shortness, when we consider their comparatively large 
 size. Thus, in a specimen one inch in diameter, the height of 
 the corallites is only about half a line, while the diameter of the 
 larger tubes is equal to their height. The corallites are of two 
 kinds, large and small ; or, in other words, to use the nomen- 
 clature of Milne-Edwards and Haime, the corallites are sur- 
 rounded by “ ccenenchymal tubes.” In view, however, of the 
 researches of Moseley upon Heliopora , we shall consider the 
 smaller tubes to be really of the nature of corallites, tenanted, 
 probably, in the living condition by a peculiar kind of zooids. 
 The larger and smaller corallites are symmetrically arranged 
 upon the upper surface of the epitheca, the former being dis- 
 posed in intersecting rows, and being isolated and separated 
 from one another by the latter. In the only species of the 
 genus known, the amount of the smaller tubes is not large, but 
 there is always a single zone of them surrounding each of the 
 large tubes (PI. III., fig. 3^). The large corallites, except in 
 their shortness, are constructed upon the type of Heliolites , the 
 resemblance between the two genera being especially manifest 
 in the presence of short septa, apparently always twelve to each 
 corallite when well preserved. The septa, however, are not so 
 well developed as in Heliolites , being mere short blunt ridges 
 (PL III., fig. 3 d). They are wholly wanting in the small tubes, 
 as is also the case in Heliolites . Considering the extreme 
 shortness of the corallites, the tabulae may be said to be well 
 developed, and they are always strong and complete. In the 
 large tubes the tabulae are confined to the bottom of the vis- 
 ceral chamber (PI. III., fig. 3^), and there is generally only one 
 of them, though there may be two, or sometimes even three or 
 four ; though in the latter case they are very closely approxi- 
 mated. In the smaller corallites the tabulae are more exten- 
 sively developed, and they extend to close upon the summit of 
 
54 
 
 ACTINOZOA. 
 
 the tubes (PI. III., fig. 3^). Lastly, the walls of the corallites 
 are of considerable thickness, but wholly without mural pores, 
 and the axis of the visceral chamber is never traversed by a 
 columella. 
 
 As to the affinities of the genus Pinacopora , we are disposed 
 to regard it as a member of the Alcyonarian family of the 
 Hclioporidce of Moseley, and to place it in the neighbourhood 
 of Heliolites , this being the only genus known to us with which 
 it presents any relationship. It agrees, in fact, with Heliolites 
 in the important feature that the corallum consists of a series 
 of full-sized corallites, furnished with tabulae, and with short 
 septa, which are typically twelve in number ; while these are 
 surrounded and isolated by a series of smaller tubes, which are 
 more closely tabulate, but are without septa. On the other 
 hand, it differs from all known species of Heliolites in its form- 
 ing a thin, concavo-convex, leaf-like plate ; in the extraordinary 
 shortness of its corallites ; in the comparatively rudimentary 
 condition of the septa ; and in the small number of the smaller 
 tubes, and the absence in them of anything like a regular or 
 geometric form, while their tabulae are remote and compara- 
 tively irregular. 1 
 
 There is no other genus with which we find it necessary to 
 compare Pinacopora in detail, but we may just notice the 
 possibility that some of the forms upon which Hall founded 
 the genus Lichenalia may perhaps turn out, when fully ex- 
 amined, to belong to the present genus, though others are 
 probably of a different nature. 
 
 Pinacopora Grayi, Nich. and Eth., jun , sp. nov. 
 
 (PI. III., figs. 3-3 /.) 
 
 Spec. char. — Corallum composite, in the form of a concavo- 
 convex, leaf-like, calcareous expansion, of circular or oval form, 
 
 1 The resemblance between Pinacopora and Heliolites is not conspicuously strik- 
 ing, except with one or two forms of the latter genus, such as Heliolites dubia, Fr. 
 Schmidt, in which the larger tubes are closely applied to one another, and the 
 coenenchyma is reduced to a minimum. 
 
PINA COPORA. 
 
 55 
 
 varying from six to sixteen lines in diameter. Concave surface 
 of the discoid corallum covered by a concentrically-striated 
 calcareous epithecal plate. Upper convex surface of the disc 
 completely covered with extremely short corallites, of two 
 sizes, the height varying from two-thirds of a line to nearly 
 a line. Large-sized corallites oval or nearly circular in shape, 
 averaging about two-thirds of a line in diameter, completely 
 open above, but occupied below by one, two, or rarely more, 
 strong and complete tabulae. Short septal ridges, typically 
 twelve in number, also extend towards the interior of the 
 visceral chamber. The larger corallites are regularly arranged 
 in obliquely intersecting lines, and are completely surrounded 
 by a zone of small tubes, averaging one-fifth of a line in diam- 
 eter. These smaller tubes are very variable in shape, but 
 they are furnished with strong and remote tabulae to near 
 their summits, and they are devoid of septa. Generally only 
 a single row of small tubes intervenes between any given 
 pair of large tubes, but there may be a partial duplication 
 of this by the occasional development of additional tubuli 
 in places. 
 
 Obs . — As there is only this single species in the genus, and 
 as we have discussed the characters of the latter in detail, we 
 need only add here a few remarks on the condition of pre- 
 servation of the specimens with which we have worked. The 
 cabinet of Mrs R. Gray contains a large and instructive series 
 of examples from the mudstone of Mulloch Hill — the sole 
 locality known for the species — and the following are the 
 principal variations in the mode of their occurrence : — 
 
 (i.) In some specimens nothing whatever is to hand except 
 the cast of the under surface of the epitheca. 
 
 (2.) In others, the polypiferous surface of the corallum is 
 embedded in the stone, so that nothing is visible except the 
 striated and concave under surface of the epitheca (PI. III., 
 fig. 3) ; but this has its structure preserved, and vertical sections 
 of these specimens yield excellent results. 
 
 (3.) In others, again, we have the cast of the zipper convex 
 
ACTINOZOA. 
 
 56 
 
 surface of the epitheca (PI. III., fig. 3 a), from which all the 
 corallites have been broken off. 
 
 (4.) In other very instructive examples, while part of the 
 epitheca is shown as a cast (as in the preceding), the rest of 
 the original epithecal plate, along with the bases of the coral- 
 lites, has been preserved (PI. III., fig. 3 b) y the upper portions 
 of the latter being broken off. 
 
 (5.) In a fifth group of specimens, the actual calcareous 
 corallum is wholly preserved, but, thin as it is, it has given 
 way along a plane midway between the upper and lower sur- 
 faces of the disc. In such cases, one side of the split stone 
 shows the convex upper side of the epithecal plate and the 
 bases of the corallites which it supports ; while on the other 
 piece we have a corresponding concavity, which is occupied by 
 the upper portions of the corallites, the actual mouths of which 
 are embedded in the stone, and which the spectator thus looks 
 at from below (PI. III., fig. 3 k). 
 
 (6.) Lastly, there are many beautiful, and at first sight very 
 puzzling, specimens in which we have casts of the upper or 
 polypiferous side of the corallum (PL III., figs. 3 f and $g). 
 These casts are circular or oval, and always concave, as cor- 
 responding with the convex upper surface of the coral upon 
 which they are moulded. They exhibit a series of short 
 columns, directed at right angles to the plane of the cast, 
 about half a line in height, and the same in diameter, oval or 
 circular in shape, arranged in intersecting lines, and indented 
 on their sides with twelve vertical sulci. These columns are 
 the casts of the large-sized corallites, and they are separated 
 by interspaces which represent the zone of smaller tubes by 
 which each of the latter is surrounded. These smaller tubes, 
 being tabulate to close upon their summits, do not appear to 
 have been penetrated by the surrounding matrix to any extent, 
 so that one can only very indistinctly make out any projections 
 in the cast, which might be considered as representing the 
 cavities of these. We have named this interesting form in 
 honour of our friend, R. Gray, Esq., F.R.S.E. 
 
J 1 ELI O LITE S. 
 
 57 
 
 Form . and Loc. — Not uncommon in the mudstones (Upper 
 Silurian) of Mulloch Hill. {Coll., Mrs R. Gray.) We may 
 add that we have seen specimens in the collection of Mr 
 George Jennings Hinde of a species of coral from the “junc- 
 tion-beds” of Anticosti (base of Upper Silurian), which is 
 undoubtedly congeneric with Pinacopora Grayi. 
 
 Genus Heliolites, Dana, 1846. 
 
 (Zooph., p. 541.) 
 
 Heliolites interstincta, Linn. 
 
 Madrepora interstincta , Linne, Syst. Nat., ed. xii., p. 1276, 1767. 
 
 Madreporites inter stinctus, Wahlenberg, Nov. Acta Soc. Scient. Upsal., vol. 
 viii. p. 98, 1821. 
 
 Porites pyriformis , Lonsdale, in Murchison’s Silurian System, p. 686, 1839. 
 
 Paleeopora interstincta , M‘Coy, Brit. Pal. Foss., p. 15, 1851. 
 
 Heliolites interstincta , Milne-Edwards and Haime, Pol. Foss, des Terr. Pal., 
 p. 214, 1851. 
 
 „ pyriformis , Hall, Pal. N.Y., vol. ii. p. 133, 1852. 
 
 „ interstincta , Milne-Edwards and Haime, Brit. Foss. Corals, p. 249, 
 1854. 
 
 (For full synonymy up to date, see Milne-Edwards and Haime’s Monograph 
 of British Fossil Corals, p. 249.) 
 
 Obs. — We have a few specimens which we are enabled to 
 identify with this widespread and familiar form. All but one 
 of our examples are simply in the condition of casts ; but one 
 small specimen from another locality (Penkill) is infiltrated with 
 carbonate of lime, and was therefore in a condition suitable for 
 microscopic examination. All the specimens, however, appear 
 to be clearly referable to Heliolites interstincta , with which they 
 agree in possessing large calices about three-quarters of a line 
 in diameter, separated by spaces of about half a line, which are 
 occupied by polygonal corallites of from i-6th to i-8th of a line 
 in diameter. 
 
 Form, and Loc. — In the condition of casts in the dark- 
 green mudstones of Mulloch Hill. Also at Penkill, near 
 Girvan, the strata at both these localities being of Upper 
 
ACTINOZOA. 
 
 55 
 
 Silurian age. (Coll., Mrs R. Gray). We have no doubt 
 that our specimens are specifically identical with those quoted 
 by Salter under the name of Heliolites subrotundus , Fougt 
 ( = Porites pyriformis , Lonsd.), as occurring at Mulloch (Quart. 
 Journ. Geol. Soc., vol. vii. p. 1 7 1 ). 
 
 Heliolites Grayi, Miln e-Edwards and Haime (?). 
 
 (PL IV., figs. 4 and 4a, and PL V., fig. 1.) 
 
 Heliolites Grayi , Milne-Ed wards and Haime, Pol. Foss, des Terr. Pal., p. 
 
 217, 1851. 
 
 „ „ Milne-Edwards and Haime, Brit. Foss. Cor., p. 252, 1854. 
 
 Spec. char. — Corallum forming irregularly-branched or sub- 
 lobate masses, which when of large size are clearly formed by 
 the superposition of successive layers of corallites upon one 
 another. In branched specimens the branches are cylindrical 
 or flattened, sometimes palmate or lobulate, from four to about 
 seven lines or more in diameter. The larger masses are irreg- 
 ularly lobed, and sometimes attain a diameter of one to two 
 inches. The corallum appears to have been rooted at the base, 
 and to have had all its free surface covered with the calices. 
 The larger calices are half a line in diameter, or very slightly 
 less, and they are separated by interspaces of from one-third of 
 a line to half a line. The smaller tubes (“ coenenchymal tubes ”) 
 are minute, four or five of them occupying an interspace be- 
 tween any pair of large tubes, and they appear to be irregular, 
 or somewhat vermiculate in shape. There are twelve septa, 
 with broad bases, and narrow interseptal chambers, in each of 
 the larger tubes. Tabulae unknown. 
 
 Obs. — The Craighead limestone has yielded a considerable 
 number of specimens of coral with the characters above given, 
 which we identify, with a little hesitation, with the Heliolites 
 Grayi of Edwards and Haime. In most respects our specimens 
 agree well with those ascribed to H. Grayi by its describers. 1 1 
 has the same peculiar mode of growth, and is often (though by 
 
HE LI OL I TES. 
 
 59 
 
 no means always) in the form of thick lamellar branched expan- 
 sions, while its larger calices have the same diameter and the 
 same number of thick triangular septa. Edwards and Haime, 
 however, give as a specific character that the larger calices are 
 “ limited by a small, well-marked, circular ridge,” formed by the 
 exsert edge of the septa ; but we cannot lay much stress upon 
 the apparent absence of this in our forms, as with hardly an 
 exception their surface-characters are absolutely undeterminable, 
 and in the best of our specimens are exceedingly badly pre- 
 served. Upon the whole, therefore, we are tolerably confident 
 that we are right in regarding the Craighead specimens as 
 identical with the unique Heliolites Grayi , Edw. and H., of the 
 Wenlock Limestone. 
 
 On the other hand, we entertain a little doubt as to the true 
 generic position of this species, in spite of its close superficial 
 resemblance to Heliolites . Could we rely with safety upon the 
 appearance presented by microscopic preparations of our speci- 
 mens, we should unhesitatingly remove it from Heliolites , since 
 these do not exhibit a trace of tabulae, and have other peculi- 
 arities as well. Unfortunately, however, they are so highly 
 mineralised that we have found it extremely difficult to make 
 satisfactory sections of them, and we cannot assert positively 
 that both some of the positive and the negative phenomena 
 which we have observed are not really due to the mode of 
 preservation of the specimens." Still, it should be borne in 
 mind that Milne- Edwards and Haime .give no details as to 
 the minute internal structure of Heliolites Grayi , and that the 
 form and mode of growth of the corallum are very peculiar 
 in this species, so that its reference to Heliolites will require 
 confirmation. 
 
 Transverse sections of our specimens (PI. V., fig. i) remind 
 us far more of such perforate corals as Protarcea and Stylarcsa 
 than of Heliolites. The stellate sections of the larger corallites, 
 with their twelve broad septa, are evident enough, but the 
 intervening tubules are only to be made out with difficulty, if 
 at all, while they are often irregular and elongated in shape, 
 
6o 
 
 ACTINOZOA. 
 
 thus closely resembling what we see in cross sections of the 
 reticulate sclerenchyma of Protarcea. On the other hand, in 
 sections taken parallel with the larger tubes (PL IV., fig. 3 a), 
 the appearances presented are very puzzling, though it is quite 
 probable that they are only due in reality to the undoubted 
 changes which the specimens have undergone subsequent to 
 fossilisation. They show, in fact, no distinction between the 
 larger and smaller tubes, and absolutely no traces of tabulcz ; 
 but they simply exhibit irregular, overlapping, and wavy lines, 
 which run parallel with one another, and look as if they repre- 
 sented the division-walls between contiguous tubes. Sections 
 taken across the branches of the corallum often clearly show 
 that increase to its growth was effected by means of the addi- 
 tion of successive layers of short corallites. These sections 
 also often show the characters of the surface to some extent 
 (PI. IV., fig. 30), and we learn from them that the actual cup 
 of the larger corallites extended about half a line below the 
 surface, its floor having often two or three tooth-like projec- 
 tions, while the smaller calices extended only to about one- 
 sixth of a line or less below the surface. 
 
 Form . and Loc . — Not uncommon, but very badly preserved, 
 in the limestone at Craighead, near Girvan. ( Coll ., Mrs R. 
 Gray, and Coll., H. A. Nicholson). 
 
 Genus Stylar^a, Von Seebach, 1866. 
 
 (Zeitschr. d. deutsch. Geol. Ges., Bd. XVIII. p. 304.) 
 
 Gen. char . — Corallum composite, the sclerenchyma traversed 
 by numerous fine inosculating canals. Corallites short, opening 
 on the surface by rounded or polygonal calices, of moderate 
 depth. Septa in the form of a variable number of short blunt 
 ridges extending into the interior of the visceral chamber, the 
 axis of which is occupied by a well-developed circular or oval 
 columella, which the septa do not nearly reach. Strong and 
 complete tabulae present or absent. Corallum encrusting, or (?) 
 attached only at a single point. 
 
STYLAR/EA. 
 
 6 1 
 
 Obs. — The genus Stylarcza 1 was founded by Von Seebach 
 (loc. cit.) for certain corals from the Lower Silurian of Esthland, 
 which entirely agree with the well-known Protarcea of Milne- 
 Edwards and Haime in most points, but are essentially dis- 
 tinguished by the possession of a well-developed columella. 
 Protarcea , as is well known, always occurs in the form of thin 
 crusts attached parasitically to foreign bodies, and some of its 
 peculiarities may be merely adaptations to its special habit of 
 growth. Stylarcea , however, must be so far different to Pro- 
 tarcea in habit, that it is stated to possess a distinct epitheca, 
 which is hardly consistent with the use of the term “ encrust- 
 ing” employed by Von Seebach in his generic description. 
 In their reticulate sclerenchyma, tuberculated walls, and short 
 crenulated septa, the two genera are completely identical. 
 
 Amongst the specimens collected by Mrs R. Gray from 
 Craighead, we find one which we cannot possibly place else- 
 where than in the immediate neighbourhood of Protarcea , and 
 which we think ought to be considered as a species of Stylarcea , 
 though in order to place it in this genus, some extension of the 
 characters of the latter, as given by Von Seebach, is necessary. 
 Our form agrees with both Protarcea and Stylarcea in the 
 minute structure of the sclerenchyma, in the form and dispo- 
 sition of the calices, and in the characters of the septa ; while 
 it further agrees with the latter genus in the possession of a 
 strong and well-developed columella. This columella, how- 
 ever, cannot be said to be “ spongy,” as stated in Von Seebach’s 
 definition, for it is quite compact ; and though we are unfor- 
 tunately unable to say positively what was the mode of growth 
 of our species, it certainly possessed much longer corallites 
 than was the case with either Protarcea or Stylarcea , and can 
 hardly be stated to have been “ encrusting.” Moreover, there 
 is the very important point that the corallites in our form are 
 provided with strong and well-developed tabulce , structures 
 
 1 So far as we can judge from his figures and description, the genus Coccoseris of 
 Eichwald (Leth. Ross., vol. i. p. 442, PI. XXV., fig. 4) is founded upon corals very- 
 similar in structure to Styla?'<za, Von Seebach, if not absolutely identical with the 
 latter. 
 
62 
 
 A CTINOZOA. 
 
 which are wholly wanting in the two genera just mentioned. 
 The absence of tabulae, however, in Stylarcea Roemeri , and in 
 Protarcea , may well be due to the extreme shortness of the 
 corallites in these forms, and for this reason we are not disposed 
 to attach a generic value to their presence in our species. 
 Without ignoring the differences which we have just alluded 
 to, the general structure of the Ayrshire coral is so entirely 
 similar to that of Protarcea vetusta , Hall, — as we have fully 
 satisfied ourselves by a careful microscopic examination of both 
 — that we should not feel justified in removing it far from 
 the latter, and its possession of a columella would naturally 
 place it in Stylarcea. If this reference be admitted, we must 
 not only allow the occasional presence of tabulae as one of the 
 characters of the genus Stylarcea , but we have to note a further 
 confirmation of the now acknowledged fact that well-developed 
 tabulae may exist in unquestionable perforate corals. 
 
 Stylaraea occidentalis, Nich. and Eth., jun., sp. nov. 
 
 (PI. IV., fig. 2-2 b.) 
 
 Spec . char . — Corallum composite, forming a flattened ex- 
 pansion (?), of small size. Corallites irregularly cylindrical, 
 about half a line in diameter, separated by thick sclerenchyma, 
 which is equal in thickness to half the diameter of the tubes or 
 more, and is traversed by numerous inosculating canals (PI. IV., 
 figs. 2 and 2 a ), whereby each corallite is brought into com- 
 munication with those immediately surrounding it. Calices 
 slightly depressed, about half a line in diameter. Septa in the 
 form of short blunt ridges, with broad bases (PI. IV., fig. 2), 
 which extend inwards for a variable distance into the visceral 
 chamber, but always fall far short of the columella. Usually 
 eight principal septa, sometimes with indications of as many 
 short secondary septa alternating with them. Tabulae strong, 
 straight or curved (PI. IV., fig. 2 b\ placed at distances of 
 from one-fifth to one-quarter of a line apart. Columella strong 
 and compact, generally circular, and extending through the 
 
CAL0STYL1S . 
 
 63 
 
 tabulae as a continuous rod in the axis of the visceral chamber, 
 the course of the latter not being thereby deflected. 
 
 Obs. — The only described species of Stylarcea — viz., S.Rcemen 
 — is stated by Von Seebach to form thin laminar expansions, 
 and to resemble Protarcea vetusta , Hall, in all essential points 
 except in its possession of a columella. (We may here note, 
 however, that Protarcea vetusta is seen in vertical sections not 
 uncommonly to possess a predominant tubercle in the floor 
 of the calice, as shown in PI. IV., fig. 3 a; and this may per- 
 haps be regarded as a rudimentary columella.) S. occidentalis 
 appears to have grown in the form of a thin expansion, but 
 as our material consisted of only a single specimen, we cannot 
 assert anything positive as to its mode of growth. The coral- 
 lites, however, in this specimen, are no less than three lines in 
 height, and therefore greatly exceed those of Protarcea vetusta 
 in this particular; and Von Seebach does not state that the 
 tubes of his Stylarcea Rcemeri are any higher than those of the 
 latter form. Apart from this difference, however, our species 
 is fundamentally distinguished from that of Von Seebach by 
 its possession of strong and complete tabulae, by its compact, 
 not spongy, columella, and by the absence of crenulation of 
 the septa, these structures being apparently primarily eight 
 in number. 
 
 Form, and Loc . — Rare in the shales associated with the lime- 
 stone at Craighead, near Girvan. {Coll., H. A. Nicholson). 
 
 Genus Calostylis, Lindstrom, 1868. 
 
 (Ofversigt K. Vetenskaps-Akad. Forhandl., 1868, p. 421.) 
 
 Gen. char. — Corallum compound or simple, increasing by 
 lateral gemmation ; wall rudimentary ; epitheca poorly de- 
 veloped or wanting ; septa porous, united with one another 
 by lateral processes or imperfect dissepiments, continued cen- 
 trally into a loosely reticulate or trabecular columella. Rudi- 
 mentary tabulae present or absent. 
 
ACTINOZOA. 
 
 64 
 
 Obs. — The genus Calostylis was founded by Lindstrom for 
 some very remarkable corals from die Upper Silurian of Got- 
 land, which had previously been described by Kjerulf under 
 the name of Clisiophyllum denticulatum. Lindstrom, however, 
 showed (loc. cit.) that the form in question had no relation to 
 the genus above named, but that it was truly the type of a new 
 group of Palaeozoic Perforate Corals, which, as far as known, are 
 the only representatives of the Eupsammidce / which have been 
 discovered in the entire series of the Palaeozoic deposits. The 
 peculiarities of Calostylis denticulata were subsequently de- 
 scribed in greater detail by Lindstrom in a paper entitled 
 “Description of the Anthozoa Perforata of Gotland” (Kongl. 
 Svenska Vetenskaps - Akad. Handl., Bd. ix., 1870); and we 
 are entirely able to confirm the general accuracy of the account 
 there given, as we have made a careful microscopic examina- 
 tion of specimens which he himself kindly presented to us. We 
 agree, therefore, with him in the conclusion that Calostylis is a 
 true Perforate Coral, belonging to the family of the Eupsam- 
 midce, and related to the genera Endopsammia and Balano- 
 phyllia . Lindstrom points out, however, that C. denticulata 
 possesses some characters which remind one of the Rugosa, 
 such as the existence of epithecal outgrowths, which occasion- 
 ally act as processes of attachment. In a longitudinal thin 
 section which we have prepared of this species, we further find 
 that the visceral chamber is crossed by distinct though some- 
 times discontinuous horizontal plates, which appear to be clearly 
 of the nature of tabulae. Whether these structures are always 
 present or not is a point which we are unable to determine, but 
 their occurrence is not alluded to by Lindstrom. 
 
 The “ Gray collection ” contains a number of specimens of a 
 small coral which are at once shown by microscopic examina- 
 tion to agree in every particular with Calostylis , and which 
 differ from C. denticulata , Kjerulf sp., only in points of specific 
 
 1 ’ Pcilceacis , Haime, has been regarded as a Carboniferous representative of the 
 Eupsammidce , but we have elsewhere given reasons (Ann. Nat. Hist., 1878) for 
 thinking that it is not referable to the Actinozoa. 
 
CALOSTYLIS. 
 
 65 
 
 importance. This coral we shall describe under the name of 
 Calostylis Linds tromi ; and its occurrence is of special interest, 
 as it affords the first known instance of the discovery of this 
 remarkable and ancient type of Perforate Corals outside of the 
 Silurian rocks of Sweden. 
 
 Calostylis Lindstromi, Nich. and Eth., jun., sp. nov. 
 
 (PI. V., figs. 2-2 c.) 
 
 Spec. char . — Corallum simple, or sometimes throwing out a 
 few lateral buds, cylindrical, contorted, and generally more or 
 less constricted at intervals, the usual diameter of seemingly 
 full-grown specimens being from two to three lines. No wall. 
 An epitheca, of small thickness, may be partially developed ; 
 but in other cases the outer edges of the septa appear on the 
 surface as so many longitudinal ridges. Septa porous and 
 cribriform, irregular, the larger ones thirty or more in number, 
 sometimes with smaller septa which become coalescent with the 
 larger ones. Centre of the corallum occupied by a very loosely 
 reticulated and trabecular mass, which represents a spongiose 
 columella occupying about one-third of the total diameter of 
 the corallum. In the interval between the columella and the 
 wall on each side, delicate and remote plates representing 
 tabulae can be detected. Contiguous septa send out imperfect 
 tooth-like dissepiments by which they are loosely united to one 
 another. 
 
 Obs. — This remarkable species can generally be without 
 difficulty picked out by its slender, cylindrical corallum, appa- 
 rently always more or less twisted, and usually constricted at 
 intervals (PI. V., fig. 2) — superficial characters exhibited by 
 none other of the Girvan corals known to us. Its size 
 varies from half an inch to nearly an inch in length, with an 
 average diameter of about two lines ; but none of our speci- 
 mens can be certainly said to be perfect, so we do not know if 
 this length was exceeded or not. Towards the base the cor- 
 allum tapers, and most of the specimens appear to have been 
 
 E 
 
66 
 
 ACTINOZOA. 
 
 simple. Some, however, show distinct lateral buds, though we 
 have not noticed more than one such bud in any given indi- 
 vidual. In the points just mentioned, the present form agrees 
 with C. denticulata , which sometimes has a simple conical cor- 
 allum, and at other times produces lateral buds. Its surface- 
 characters — as almost universally with the Girvan corals — are 
 extremely badly preserved ; but we sometimes recognise a thin 
 epitheca, which, at places where the corallum is constricted or 
 contorted, may be developed into thickened encircling ridges. 
 At other times, the surface shows longitudinal ridges formed 
 by the outer edges of the septa. The characters of the calice, 
 and the mode of attachment of the coral, are unknown to us. 
 
 Microscopic sections at once reveal the structure and true 
 affinities of Calostylis Lindstromi. These show that the entire 
 corallum is made up of reticulate and trabecular sclerenchyma. 
 The septa are well developed, comparatively speaking ; but as 
 the shorter ones often become confluent with the larger as the 
 latter in turn pass into the central spongy mass, and as all are 
 more or less united together by lateral processes, it is very 
 difficult to determine their number precisely. There appear to 
 be about thirty principal septa in a specimen of three lines in 
 diameter. Long sections show that imperfect horizontal parti- 
 tions or tabulae (PI. V., fig. 2 c ) are present, and that the septa 
 are more or less largely cribriform ; while both longitudinal 
 and transverse sections show that the axis of the visceral 
 chamber is occupied by a broad cylindrical mass of columellar 
 tissue in the form of reticulating and inosculating trabeculae 
 (PI. V., figs. 2 b and 2 c). 
 
 Calostylis Lindstromi , though agreeing with C. denticulata , 
 Kjerulf, in its general plan of structure, is readily separated 
 from it by its very much smaller dimensions, and the contortion 
 and periodic constriction of all specimens known to us. It 
 also has much fewer septa, and does not appear to produce 
 epithecal processes of attachment. On the other hand, C. 
 denticiclata — the only other known representative of the type — 
 attains a maximum length of from four to six inches, with a 
 
STREPTELA SM A. 
 
 67 
 
 diameter of an inch and a quarter, while its septa reach the 
 great number of one hundred and forty, and in the early stages 
 of its growth it fixes itself by root-like epithecal processes 
 developed from the border of the calice. 
 
 We have named the species in honour of our friend Dr 
 Gustav Lindstrom, one of the most distinguished of authorities 
 on the subject of fossil corals. 
 
 Form . and Loc . — Apparently not uncommon in the greenish 
 mudstones of Penkill, near Girvan, of Upper Silurian age. 
 (Gray collection). 
 
 Genus Streptelasma, Hall, 1847. 
 
 Streptelasma, Hall, Pal. N.Y., vol. i. p. 17, 1847. (By clerical error, sub- 
 sequently corrected, the name of the genus is spelt Strepto- 
 plasma). 
 
 „ Milne-Edwards and Haime, Pol. Foss, des Terr. Pal., p. 398, 
 
 1851. 
 
 Petraia (pars), M‘Coy, Brit. Pal. Foss., p. 39, 1851. 
 
 Palezophyllum , Billings, Geol. Survey of Canada, Rep. of Progress, p. 168, 
 
 1857- 
 
 Streptelasma , Ferd. Roemer, Die foss. Fauna von Sadewitz, p. 17, 1861. 
 
 „ Kunth, Zeitschr. d. deutsch, Geol. Ges., 1871, p. 647. 
 
 „ Dybowski, Mon. Zoanth. sder. Rug., p. 125, 1873. 
 
 „ Nicholson, Pal. of Ohio, vol. ii. p. 217, 1875. 
 
 „ Nicholson, Ann. and Mag. Nat. Hist., Ser. 4, vol. xviii. p. 94. 
 
 Gen. char . — Corallum simple, cylindrical or turbinate ; or 
 compound and more or less fasciculate. Epitheca well de- 
 veloped. Proper wall doubtfully present ; but a thick false 
 wall, formed by the fusion of the broad outer ends of the septa 
 with intermediate calcareous deposit. Septa well developed, 
 lamellar, of two orders, the primary septa usually more or less 
 flexuous, and always more or less extensively united at their 
 inner ends with one another and with a pseudo-columella, 
 which is composed of the twisted and inosculating edges of the 
 septa ; secondary septa of approximately equal size, much 
 shorter than the primary septa, with which they are often 
 united by their inner ends. Dissepiments in variable number 
 
68 
 
 ACTINOZOA. 
 
 intersect the interseptal spaces, but never exist in amount 
 sufficient to constitute an outer vesicular zone. Tabulae are 
 well developed in the outer zone of the corallum, but often do 
 not completely cross from side to side. They are usually more 
 or less convex upwards externally, and flat or convex centrally. 
 A septal fossula present or absent. 
 
 Obs. — As regards the history of the genus Streptelasma we 
 have but little to remark. It was originally founded by Hall 
 {loc. cit .) upon the still undetermined and imperfectly under- 
 stood kSI expansa of the Chazy Limestone ; and almost the only 
 character of importance given in the generic diagnosis is that 
 the septa are more or less spirally twisted in the centre. As 
 the true structure of S. expansa is, however, still unknown, we 
 must take the common and sufficiently investigated S. cor- 
 niculum of the Cincinnati group as the type of the genus — a 
 course the more justifiable as this species was described by Hall 
 in the same volume and in the same year as S. expansa (Pal. 
 N.Y., vol. i. p. 69). As the twisting of the primary septa in 
 the centre of the visceral chamber is not particularly marked 
 in Streptelasma , and as this feature is found in corals of very 
 different affinities, it is not surprising that Milne-Edwards and 
 Haime {loc. cit.) regarded the genus with some doubt, and only 
 retained it upon the ground that the well-preserved specimens 
 which they had seen rendered it certain that the coral is “ des- 
 titute of an epitheca and covered by sub-lamellar costae.” This 
 statement can only be explained upon the supposition that the 
 eminent observers just named founded their remarks upon 
 specimens which were really weathered and decorticated, since 
 all the well-preserved examples of the genus which we have 
 seen possess a distinct, though sometimes thin, epitheca. It is 
 also probable that some of the so-called “ Petr aice" will prove 
 to be really referable to Streptelasma , and this is certainly the 
 case with at least one species of M ‘Coy’s Strephodes . The 
 only other point connected with the history of the genus which 
 needs notice is the establishment, in 1857, by Billings {loc. cit.), 
 of the genus Palceophyllnm to include forms which only differ 
 
STREPTELA SMA. 
 
 69 
 
 “ from Pet rciici or Streptelasma in forming long fasciculate or 
 aggregate masses, instead of being simple.” The generic 
 diagnosis given by Billings is very brief and imperfect, and the 
 only structural point of importance noted in it is, that the tabulae 
 are “ either none or rudimentary.” This, if certainly estab- 
 lished, would separate the genus from Streptelasma , as we now 
 understand it ; but in the absence of information as to the 
 microscopic structure of the type-specimens, it would be hazar- 
 dous to attach much weight to this ; and there remains, there- 
 fore, only the composite character of the corallum to consider. 
 This, no doubt, is often considered as of itself sufficient to 
 establish generic distinction, and we do not desire to express 
 any opinion on this practice ; but in this particular instance we 
 think that it would be, at any rate, very inconvenient to adopt 
 a similar course. Our reason for this opinion is, that though 
 certain specimens, and certain species, can be said with certainty 
 to be simple, while others with equal decision can be said to 
 be compound, there are many broken examples which cannot 
 be asserted positively to be one or the other, so that in the case 
 of some species it becomes impossible to say if the corallum 
 was always compound. This is the case, for example, with 
 •S'. Craigense , M‘Coy, sp., which, though certainly usually 
 simple, cannot be structurally separated from examples exhib- 
 iting multiplication by division. For this reason we prefer at 
 present to consider the genus P alee op hy llum, Bill., as, at most, 
 a sub-genus of Streptelasma . 
 
 From its minute structure, as elucidated by microscopic sec- 
 tions, the affinities of Streptelasma become abundantly clear. 
 It is a Zaphrentine, and not a Cyathophylloid type. This is 
 shown quite conclusively by the condition of development of 
 the dissepiments alone, which, in all the true Cyathophylloids, 
 are present in such quantity as to give rise to a regular exterior 
 zone of vesicular tissue, the central twisting together of the 
 septa being a wholly secondary feature. In all the Strepte- 
 lasmce, however, dissepiments are present in small number ; and 
 they agree further with Zaphrentis in possessing, without excep- 
 
7 ° 
 
 ACTINOZOA. 
 
 tion, well-developed tabula. Their special points of differen- 
 tiation from Zaphrentis are to be found in the presence of a 
 central reticulate pseudo-columella, and in the condition of the 
 fossula. In all forms of Streptelasma, the axis of the visceral 
 chamber is occupied by a very loosely constructed pseudo- 
 columella, which often projects in the floor of the calice as a 
 rounded boss, while in cross-sections it is seen to be formed by 
 the irregular anastomosis centrally of a certain number of the 
 primary septa. In long sections of the corallum, taken across 
 the median line, it is equally conspicuous as a series of irregular 
 and disconnected vertical rods. This pseudo-columella must 
 be considered as the special feature distinguishing Streptelasma 
 from Zaphrentis. On the other hand, the condition of the 
 septal fossula varies. In S. corniculum , Hall, which, as before 
 said, we may take as the type of the genus, a septal fossula is 
 present, though this is not formed by the coalescence of a num- 
 ber of the primary septa. In other species (S. aggregation, S. 
 Craigense , &c.) we have failed to find any indications of a fos- 
 sula at all. Upon the whole, therefore, we must rely upon the 
 axial structure of the corallum, as separating Streptelasma 
 and Zaphrentis ; and we obtain thus an additional proof of the 
 necessity of breaking up the latter genus. Some of the forms 
 which would usually be referred here, will doubtless turn out to 
 be referable to Streptelasma. Others, such as Zaphrentis cylin- 
 drica , E. and H., must form the type of a new genus ; and 
 others, again, of the type of 2". Guerangeri, E. and H., will 
 remain as a compact and well -characterised group to form 
 Zaphrentis proper. 
 
 There are two other points in the structure of Streptelasma 
 which may be just alluded to. In all well-preserved specimens 
 which have come under our notice, we find, as before remarked, 
 a true epitheca to be present ; but we have not been able to 
 satisfy ourselves as to the existence of any proper wall. All 
 the forms of the genus known to us have the visceral chamber 
 bounded by a thick and dense investment, which looks at first 
 sight like a true wall, but which seems really to be a kind of 
 
STREP TELA SMA. 
 
 7i 
 
 false wall, formed by the widening out of the outer ends of the 
 septa, which are united with one another by a small amount of 
 intermediate sclerenchyma of secondary deposition (see PI. V., 
 fig. 3 b). The other point in question concerns the disposition 
 of the septa. Dr Ferd. Roemer, in describing Streptelasma 
 Europceum (Foss. Fauna von Sadewitz, p. 17 et seq.) lays con- 
 siderable stress upon the pinnate arrangement of the septa (and 
 consequently of the costae), which diverge from a dorsal, and 
 sometimes from two lateral lines. We cannot, however, agree 
 with this distinguished palaeontologist in regarding this as a 
 character of generic importance ; since it merely indicates a 
 peculiarity in the method of development of the new septa, and 
 is not only absent in some species of Streptelasma , but is pres- 
 ent in other types of different affinities. 
 
 The genus Streptelasma (including Palceophylluin) is an 
 essentially Lower Silurian type, though forms believed to be 
 referable to it are found in the Upper Silurian. Originally 
 known as abundant in the Silurian of North America, species 
 of the genus have been described by Roemer, Fr. Schmidt, 
 and Dybowski from European deposits of the same age. In 
 the Craighead limestone at Girvan, we find at least three well- 
 marked and common forms of Streptelasma , which we shall 
 next proceed to describe. 
 
 Streptelasma (Palseophyllum) aggregatum, Nich. and Eth., jun., sp. nov. 
 
 (PI. V., figs. 3-3 c.) 
 
 Spec. char. — Corallum composite, fasciculate, forming large 
 colonies of slender cylindrical corallites, which have an average 
 diameter of from two to three lines. Epitheca well developed ; 
 a thick false wall made up mostly of the thickened bases of the 
 septa, and forming a dense outer investment to the visceral 
 chamber. Calices, so far as known, deep, and having the septa 
 continued over their sides as short ridges. Septa regularly 
 developed, of two orders, the longer and shorter ones alter- 
 nating, and each series varying from twenty to twenty-five in 
 
72 
 
 ACTINOZOA. 
 
 number. No traces of a septal fossula. The septa are slightly 
 flexuous, never conspicuously twisted centrally ; but some of 
 the principal ones unite with one another at their inner ends, 
 and become connected with an irregular and loose pseudo- 
 columella, which in long sections appears to be formed of dis- 
 continuous or partially anastomosing vertical rods. Tabulae 
 well developed, convex, with their convexity directed upwards, 
 rarely or never extending completely across the visceral cham- 
 ber, three or four in the space of one line. Dissepiments vari- 
 able ; sometimes absent in individual corallites ; sometimes 
 sparsely developed in the outer zone of the tubes. Increase 
 by fission. 
 
 Obs . — This well-marked species is invariably compound, and 
 belongs, therefore, to the section Palceophyllum , Billings. Frag- 
 ments of individual corallites are found, of course ; but these 
 are in general easily distinguished from young examples of 6”. 
 Craigense , M‘Coy, either by the much smaller number of the 
 septa, or by their showing marks of division. As a rule, the 
 corallum occurs in the form of large colonies of cylindrical or 
 slightly oval corallites, pretty uniformly between two and three 
 lines in diameter, placed from two to four or five lines apart 
 (PL V., fig. 3), and completely embedded in the rock, so that 
 their characters can only be determined by microscopic exam- 
 ination. Sometimes two or three corallites occur in close con- 
 tact, or even partially united ; but this is due to their having 
 been produced by fission from a single tube — this being clearly 
 the regular mode of increase of the corallum, though, possibly, 
 lateral budding occurs as well. In PI. V., fig. 3*2, we have 
 figured the summit of an old corallite dividing into no less than 
 seven new ones, and thus appearing to increase by calicular 
 gemmation ; but more ordinarily a corallite simply divides into 
 two. Owing to the mode of preservation of the specimens, 
 little can be said as to the superficial characters. The epitheca 
 is well developed, longitudinally striated, and with delicate 
 annulations of growth, and the calice seems to have been deep, 
 with a nearly flat floor. The internal characters, however, are 
 
STREPTELA SMA. 
 
 73 
 
 thoroughly determinable. In transverse sections (PI. V., fig. 
 3 b ) we are at once struck with the great thickness and density 
 of the outer investment of the visceral chamber ; but this is 
 principally due to the thickening and fusion of the bases of the 
 septa. There are from 20 to 25 long septa, not interrupted by 
 a fossula, and regularly alternating with an equal number of 
 short septa; and the interseptal loculi, though sometimes nearly 
 or quite vacant, are usually crossed by a few, remote, curved 
 dissepiments. Some of the primary septa always unite with 
 one another by their inner ends, in groups, without being 
 notably twisted ; and they are generally more or less freely 
 connected with a central pseudo-columella, the cross-section of 
 which appears as a loosely reticulate framework in the axis of 
 the visceral chamber. In long sections (PI. V., fig. 3 e), the 
 thickness of the false wall is as conspicuous as in transverse 
 slices ; the visceral chamber is seen to be crossed by irregular 
 but well-developed curved tabulae, rarely or never quite com- 
 plete ; and the centre is occupied by the pseudo-columella, in 
 the form of a broad median band of reticulate calcareous tissue, 
 mainly made up of short longitudinal rods. 
 
 The only other species of the genus with which it is neces- 
 sary to compare the present form are Palceophyllum rugosum , 
 Bill., and P. divaricans , Nich., these being the only compound 
 members of the genus Streptelasma as yet described. In the 
 case of neither of these species is the internal structure ade- 
 quately known ; but S. aggregation is sufficiently distinguished 
 from either by its general form, since P. rugosum , Bill., forms 
 large masses of hardly separable corallites, which attain an 
 individual diameter of six lines, while the colonies of P. 
 divaricans , Nich., are composed of only from two to seven 
 short conical corallites produced by budding. 
 
 Form, and Loc . — Not uncommon in the limestone of Craig:- 
 head, near Girvan ; forming large colonies half a foot or more 
 in diameter ( Coll ., C. Lapworth, H. A. Nicholson, and Mrs 
 R. Gray). 
 
74 
 
 ACTINOZOA. 
 
 Streptelasma Craigense, M‘Coy, sp. 
 
 (PI. V, figs. 4-4 C.) 
 
 Strephodes Craigensis , M‘Coy, Ann. and Mag. Nat. Hist., ser. 2, vol. vi. p.. 
 2 7 5» 1850. 
 
 ,, „ M‘Coy, Brit. Pal. Foss., p. 30, 1851. 
 
 Cyathophyllum articulatum , Milne-Edwards and Haime, Brit. Foss. Corals, 
 p. 283, 1854. 
 
 Ptychophyllum Craigense , Lindstrom, Ofversigt af K. Vetenskaps Akad. 
 Forhandl., 1873. 
 
 Spec. char . — Corallum simple, or rarely throwing out a few 
 offsets, never forming large colonies. General form of the 
 corallum straight, cylindrical, very slowly tapering to the base, 
 full-grown examples attaining a diameter of seven, nine, or 
 eleven lines. Epitheca well developed, marked with strong 
 rounded vertical striae, six in the space of two lines, and thrown 
 into numerous conspicuous sharp-edged annulations of growth, 
 of which about five occupy the space of one inch. A thick false 
 wall formed by the fusion of the broad and widened outer 
 ends of the septa. Septa numerous, slightly flexuous, never 
 conspicuously twisted towards the centre of the corallum, of 
 two sizes regularly alternating with one another. Fully adult 
 examples have from seventy-two to eighty septa in all, half of 
 these being long and the other half short, the larger number 
 of the primary septa either being connected together in groups 
 towards the centre, or becoming directly connected with a large 
 reticulate pseudo-columella, composed of twisted and anasto- 
 mosing vertical rods occupying the axis of the visceral chamber. 
 The calice is apparently deep, but the form assumed by the 
 columella in its floor has not been observed. A few remote 
 and curved dissepiments are always developed in the inter- 
 septal loculi, but never form an exterior zone of vesicular 
 tissue. No septal fossula. Tabulae well developed, often com- 
 plete, sometimes inosculating, curved upwards in the outer 
 portions of the visceral chamber, but flat or depressed centrally, 
 about five in the space of two lines. 
 
STREPTELA SMA. 
 
 75 
 
 Obs. — We feel no hesitation whatever in identifying the 
 specimens upon which the above description is founded with 
 the Strephodes Craigensis , M‘Coy [loc. cit. ) ; nor can we feel 
 any more doubt as to their being in all respects properly refer- 
 able to the genus Streptelasma. In their great work on the 
 British fossil corals (loc. cit.), Milne-Edwards and Haime place 
 Strephodes Craigensis as a synonym of Cyathophyllum articn- 
 latum , Wahl. ; but they do not mention having seen examples 
 of the former, and the slightest examination of its internal struc- 
 ture at once shows its radical dissimilarity to any form of 
 Cyathophyllum. On the other hand, S. Craigensis is proved 
 unquestionably to be a true Streptelasma by its thick false wall, 
 composed largely of the amalgamated outer ends of the septa ; 
 its sparse dissepiments, and total absence of an exterior vesic- 
 ular zone ; its Zaphrentine tabulae ; and its large reticulated 
 pseudo-columella. Lindstrom (loc. cit.) describes a coral from 
 the Silurians of Sweden under the name of Pty chop hy llum 
 Craigense; but we are unable to say whether this is really the 
 same coral as Strephodes Craigensis , M‘Coy, or not. 
 
 From all the more ordinary forms of Streptelasma , such as 
 •S’, corniculum , Hall, S. Etiropceum , F. Roemer, and the like, 
 the present species is at once separated by its general shape. 
 No other described species of the genus possesses a corallum 
 so long, cylindrical, and slowly-tapering. None of our larger 
 specimens are perfect ; but as our larger fragments only taper 
 at a rate of about one line in nine, and as they have a diameter 
 of ten or eleven lines at the larger extremity, we should sup- 
 pose the corallum to have attained a length of at least half a 
 foot. The strong rounded longitudinal striae, and the close-set 
 and strongly-marked annulations of growth, are also good super- 
 ficial features by which fragments may be recognised. Large 
 examples of the species are invariably simple, and so cannot be 
 confounded with any of the compound forms of the genus 
 (. Palceophyllum ). We have, however, various small specimens, 
 which agree in internal structure with S. Craigense , and which 
 we suppose to be its immature form, but which present the 
 
ACTINOZOA . 
 
 76 
 
 peculiarity that they give rise to one or two corallites, appa- 
 rently by a process of fission. One of these is figured in 
 PI. V., fig. 4 c. Such specimens might easily be confounded 
 with broken fragments of a colony of .S', aggregcitum , nobis, but 
 they agree with the isolated coralla of the typical S. Craigense 
 in the large number of their septa ; and their corallites are of 
 larger diameter than even full-grown stems of S. aggregcitum. 
 
 Foi'M. and Loc . — Common in the limestone and associated 
 shales of Craighead, near Girvan. {Coll., Mrs R. Gray and 
 H. A. Nicholson.) 
 
 Streptelasma Europium, F. Roemer. 
 
 (PI. VI., figs. 1-1 b.) 
 
 Streptelasma corniculum , Fr. Schmidt, Untersuchungen fiber die Silur. Form. 
 
 von Esthland, &c., p. 233, 1861 (not Streptelasma corniculum, 
 Hall). 
 
 „ Europoeum , Ferd. Roemer, Die Sil. Fauna von Sadewitz, p. 16, 
 
 PL IV., figs. 1 a-f \ 1861. 
 
 Spec. char . — Corallum simple, conical, more or less curved, 
 varying in length (in our specimens) from one to more than 
 three inches, the diameter of the calicular extremity being 
 respectively from eight lines to an inch. Epitheca well de- 
 veloped, marked with strong rounded longitudinal ridges corre- 
 sponding with the interseptal loculi, which, in well-preserved 
 specimens, are crossed in turn by fine encircling striae. Annu- 
 lations of growth low and rounded, often inconspicuous. In 
 specimens clearly exhibiting the surface, the ridges are seen to 
 have a pinnate arrangement, being directed obliquely on both 
 sides towards a line running down the convex or dorsal side of 
 the corallum. Calice (in our examples) imperfectly preserved, 
 but always more or less oblique, and apparently of considerable 
 comparative depth. Septa of two sizes, regularly alternating 
 with one another, the total number varying in coralla of differ- 
 ent sizes from seventy-four to one hundred, but being usually 
 about eighty. No septal fossula. The secondary septa gener- 
 ally very short, and often inclined towards and fused with the 
 
STREPTELASMA . 
 
 77 
 
 primary septa at their inner extremities. Curved dissepiments 
 sparingly developed in the interseptal loculi. Towards their 
 inner ends the longer septa become more or less freely united 
 with one another and with a reticulate pseudo-columella, which 
 occupies the axis of the visceral chamber, and projects into the 
 bottom of the calice. Tabulae sometimes close-set and nearly 
 horizontal, sometimes directed obliquely upwards and anasto- 
 mosing. 
 
 c> 
 
 Obs. — The Craighead limestone has yielded to the researches 
 of Mrs Gray a number of specimens of a Streptelasma, of which 
 the above description gives the most salient characters, and 
 which we hardly think can be specifically separated from 
 Europczum , F. Roemer. It is true our examples show some 
 points of difference, but the investigation of these ancient cup- 
 corals is attended with great difficulties, and some discrepancy 
 is to be expected in specimens from widely distant localities. 
 Our specimens agree with .S. Europczum, F. Roemer, in their 
 general form, and are thus readily distinguished from the cylin- 
 drical ►S'. Cragiense , M‘Coy, sp., of the same beds. We have 
 no specimens nearly so large as the largest figured by Roemer, 
 but this is a matter of little importance. In its conical, turbi- 
 nate form, S. Europczum very closely resembles vSi corniculum , 
 Hall ; but if our specimens are rightly identified, it is separ- 
 ated from the latter (with which Schmidt placed it) by its uni- 
 formly smaller number of septa, and by the entire absence of a 
 septal fossula. According to Roemer, S'. Europczitm possesses 
 epithecal ridges which are directed in a pinnate manner along 
 three lines, one dorsal and two lateral. Most of our examples 
 have the surface much obscured by adherent matrix, or worn 
 away, and we have only been able to detect a feather-like 
 arrangement of the septal furrows on the dorsum of the coral. 
 Again, the tabulae are figured by Roemer as being nearly hori- 
 zontal, close-set, or more or less freely anastomosing in S. 
 Europczum, and our larger specimens sometimes show the 
 same feature. On the other hand, in the smaller examples, 
 the tabulae are highly inclined, with their convexity upwards, 
 
ACTINOZOA . 
 
 78 
 
 and they are rather remote. Upon the whole, however, we 
 think we are safest in identifying the Craighead specimens with 
 5 . Europceum. 
 
 Though badly preserved as regards external characters, the 
 internal structure of our specimens can be readily investigated 
 by the usual means adopted by us. Cross-sections (PI. VI., 
 fig. 1 b ) show the same general structure as in S. Craigense , 
 M‘Coy, sp. The false wall formed by the amalgamation of 
 the bases of the septa is, however, much less developed than 
 in the latter. The septa are alternately of two sizes, generally 
 about forty of each dimension being present, the shorter ones 
 being often united internally with the longer, and the interseptal 
 spaces being crossed by remote curved dissepiments. At their 
 internal extremities the primary septa are mostly united in 
 groups of from three to five, and these, in turn, become con- 
 nected with a highly-developed reticulate pseudo -columella, 
 which occupies a considerable space in the centre of the coral- 
 lum. Long sections exhibit the same general features as in 
 S. Craigense , and we have not thought it worth while to figure 
 one. We may observe, however, that the lattice-work of the 
 columella is seen conspicuously to be composed of vertical cal- 
 careous rods, irregularly uniting with one another ; that the 
 columella forms a conspicuous fasciculate projection in the floor 
 of the calice ; and that in sections taken slightly out of the true 
 line of the centre it appears simply as a series of short spines 
 springing from the upper surfaces of the tabulae. It is a sec- 
 tion of this last kind that is figured by Roemer ( loc . cit ., PI. IV., 
 fig. 1 f). As before remarked, however, long sections show a 
 variable condition of the tabulae. In old specimens, towards 
 their calicine extremities, the tabulae are nearly horizontal, and 
 are placed close together. On the other hand, they are usually 
 greatly curved, with their convexities upwards, and are then 
 comparatively remote. 
 
 Form, and Loc . — Common in the Craighead limestone, near 
 Girvan. (Gray collection.) 
 
STREPTELA SMA. 
 
 79 
 
 Streptelasma (?) sequisulcatum, M‘Coy, sp. 
 
 (PI. VI., fig. 3.) 
 
 Peiraia cequisulcata , M‘Coy, Ann. and Mag. Nat. Hist., ser. 2, vol. vi. p. 279, 
 1850. 
 
 „ „ M‘Coy, Pal. Foss., p. 39, PI. I. B, figs. 23 and 24, 1851. 
 
 Spec. char . — Corallum simple, conical, slightly curved, with 
 an oblique calice, attaining an adult diameter of from one inch 
 and a quarter to one inch and a half, with a length of two inches 
 or more. Epitheca well developed, marked by strong, obtuse 
 or flattened, longitudinal ridges, which correspond with the 
 interseptal loculi, and of which about three occupy the space of 
 one line. Septa apparently from sixty-five to eighty-five in 
 number, alternately large and small, centrally more or less 
 twisted, and sometimes inosculating with one another. Tabulae 
 unknown. Dissepiments very few and remote, curved, not 
 forming an exterior vesicular zone. Calice deep, the septa in 
 its upper portion merely marginal. 
 
 Obs . — We have a few specimens from Mulloch Hill which 
 we can identify with entire certainty with M ‘Coy’s Petraia 
 cequisulcata. Some of our examples are in the condition of 
 casts ; others retain the calcareous skeleton ; but our material is 
 unfortunately insufficient to enable us to pronounce an opinion 
 upon the true affinities of this well-marked coral. M‘Coy refers 
 it to Petraia , as defined by him, chiefly upon the ground of its 
 twisted septa, and its supposed absence of tabulae and dissepi- 
 ments. We have been unable to obtain any longitudinal sec- 
 tions, and our transverse sections are from specimens in which 
 the centre of the visceral chamber is more or less filled up with 
 matrix, to the partial destruction of the calcareous framework 
 of the coral. As to the presence or absence of tabulae we can 
 therefore say nothing. Cross-sections (PI. VI., fig. 3) show 
 the septa to be greatly twisted as they approach the centre ; but 
 this character, of itself, goes for little. Dissepiments, however, 
 are seen to be undoubtedly present, though they are but very 
 few in number, and irregular in their occurrence. Some of 
 
8o 
 
 ACTINOZOA. 
 
 the septa, however, inosculate with one another, and there are 
 indications that the centre of the visceral chamber was really 
 occupied by a trabecular columella. It is not uncommon in 
 specimens of undoubted Streptelasma to find the loosely-com- 
 pacted columella more or less broken down and replaced by the 
 matrix ; and we are at present inclined to believe that Petraia 
 aquisiilcata , M‘Coy, is really a Streptelasma , though only longi- 
 tudinal sections can set this point finally at rest. If our con- 
 jecture be correct, Streptelasma (?) cequisulcatum will stand very 
 near to S. Europaum , Roemer, from which it will be dis- 
 tinguished principally by its more curved form, more broadly 
 expanded shape, and very limited number of dissepiments. 
 Milne-Edwards and Haime (Brit. Foss. Cor., p. 280) identify 
 Petraia cequisulcata with A ulacophyllum mitratiLm , His. ; but 
 a careful microscopical examination of the latter has satisfied 
 us that there is no sufficient ground for this identification. 
 
 Form, and Loc. — Mulloch Hill, near Girvan, in beds of 
 Upper Silurian (? Upper Llandovery age). Gray collection. 
 
 Genus Lindstromia, Nich. and Thoms., 1876. 
 
 (Proc. Roy. Soc. Edin., vol. ix. No. 95, p. 149.) 
 
 Gen . char. — Corallum simple, conical or turbinate, the 
 epitheca complete, with well-marked longitudinal ridges, fine 
 encircling striae, and low annulations of growth. Septa well 
 developed, lamellar, equally developed or of two sizes, united 
 inferiorly in the axis of the visceral chamber, and augmented 
 by a secondary deposit of sclerenchyma, so as to form a com- 
 paratively enormous pseudo-columella, which projects into the 
 floor of the calice. The lower portion of the visceral chamber 
 often more or less completely filled up by the deposition within it 
 of solid sclerenchyma. Interseptal loculi, usually crossed by a 
 few strong and remote dissepiments ; and the upper portion of 
 the visceral chamber not uncommonly traversed by thick trans- 
 verse plates of the nature of tabulae, though at other times 
 
LINDSTR OMIA . 
 
 81 
 
 these are not recognisable, or at any rate have not been clearly 
 made out. 
 
 Obs. — The genus Lindstromia was founded by one of the 
 present writers and Mr James Thomson [toe. cit.), for the recep- 
 tion of certain small corals from the Devonian formation of 
 North America, the specific description of which is still unpub- 
 lished. From its general characters, which we shall discuss 
 immediately in a more detailed manner, it is clear that the 
 genus belongs to the Cyathaxonidcz , and the type to which it is 
 most nearly allied is Cyathaxonia , Michelin, itself. In this 
 genus, however, if we take into consideration the type-species 
 — viz., C. cornu , Mich. — we find that the columella is a solid 
 rod extending from the bottom of the visceral chamber to the 
 calice, that there are neither dissepiments nor tabulae, and that 
 there is a well-marked septal fossette ( see De Koninck, Nouv. 
 Recherches sur les An. Foss., Prem. partie, p. 108, 1872). In 
 Lindstromia , however, as we shall see, there is no septal 
 -fossula ; dissepiments are always present, and tabulae some- 
 times ; and the columella, or pseudo-columella, has an entirely 
 peculiar^ structure ; while there are other special structural 
 features as well. 
 
 There is, however, one species of Cyathaxonia , so called — 
 namely, C. Dalmani , Edw. and H. — which agrees in its internal 
 structure with the forms here united under the name of Lind- 
 stromia. That this well-known Silurian form is not a true 
 Cyathaxonia seems to have been recognised by De Koninck, 
 who remarks that the species of this genus “ probablement 
 sont toutes carboniferes ; ” and it has certainly been determined 
 by Lindstrom, to whose kindness we owe specimens of this 
 species, accompanied by the remark that it is not a genuine 
 Cyathaxonia , and that he proposes for it the generic name of 
 Centrotus . We are not aware of this name having been pub- 
 lished formally ; but we are not able to accept it, partly because 
 it is already preoccupied by a genus of insects, and partly 
 because we find it to be covered by the published Lindstromia , 
 and thus very appropriately designated already. The Cyath- 
 
 F 
 
82 
 
 ACTINOZOA . 
 
 axonia Siluriensis of M‘Coy (Brit. Pal. Foss., p. 36, PI. I. C, 
 fig. 1 1) is also clearly a Lindsti'dmia ; and we have determined 
 the same to be the case with at least one of the forms included 
 by M‘Coy under the head of Petraia. All these forms, except 
 Cyathaxonia Siluriensis , M‘Coy, we have now carefully exam- 
 ined by means of thin sections, and we find them to agree 
 with one another in the following general characters : — 
 
 They are all small corals, of a conical or turbinate shape, 
 with a well-developed epitheca, which exhibits longitudinal 
 ridges and encircling striae. All have a deep calice, with the 
 septa nearly obsolete at the margin, but gradually becoming 
 more prominent as we approach the floor of the cup. Those 
 in which the interior of the calice is fully known exhibit at the 
 bottom a comparatively very large and projecting columellar 
 mass, and those in which the interior of the calice has not been 
 observed can be shown by sections to possess a similar struc- 
 ture. In all, the structure of this columella, or pseudo- 
 columella, is quite peculiar, and can only be demonstrated by 
 means of transparent horizontal and vertical sections. Even 
 by this method of investigation, the subject is not without its 
 difficulties, for the lower part of the visceral chamber seems 
 to be usually, if not always, filled up in process of growth by 
 a dense secondary deposit of sclerenchyma, so that transverse 
 sections — which ought to be most instructive — vary in the 
 appearances which they present, according as they are taken 
 near the base of the corallum or near the floor of the calice. 
 Combining together the numerous sections which we have 
 made of different species of this singular genus, we find that 
 the so-called columella is really to be regarded as formed by the 
 fusion of the inner ends of the whole or a number of the septa, 
 together with a larger or smaller amount of dense calcareous 
 tissue, which is clearly of secondary and non-essential origin, 
 since it often invades the interseptal loculi, and may entirely 
 fill up the lower part of the visceral chamber. The upper 
 surface of this pseudo-columella may be quite smooth and 
 sharply defined (as in Lindstromia Dalmani , E. and H.), or it 
 
LINDSTROMIA. 
 
 83 
 
 may exhibit its real structure by presenting itself in the floor 
 of the calice as a bundle of partially fused lamellae. In any 
 case, longitudinal sections of the corallum show that it is really 
 formed in the manner above described, — namely, by the amal- 
 gamation of the inner ends of a larger or smaller number of 
 the septa, this amalgamation taking place without any twisting 
 of the septa, and being accompanied by a more or less copious 
 secondary deposition of sclerenchyma. The only other note- 
 worthy points in the structure of the corallum concern the 
 presence of dissepiments and tabulae. The former structures 
 undoubtedly exist, though they are always few in number and 
 remote in distance ; and they can by no means be invariably 
 demonstrated, especially in cross-sections taken near the base 
 of the corallum. That they always are present, however, we 
 feel tolerably certain. With regard to the existence of tabulae, 
 on the other hand, we cannot speak with the same confidence. 
 Longitudinal sections of Lindstromia ( Cyathaxonia ) Dalmani , 
 Edw. and H. (fig. 4), certainly show strong plates crossing the 
 upper part of the visceral chamber transversely, and it is im- 
 possible to regard these as being anything else than tabulae. 
 Vertical sections of Lindstromia (Petraia), subduplicata , M‘Coy, 
 and of L. Icevis , nobis, sometimes show the same thing in a less 
 marked manner ; but in these small forms it is not surprising 
 that it is difficult to pronounce a positive opinion as to the 
 presence or absence of tabulae, seeing that the whole of the 
 visceral chamber, up to the floor of the calice, is more or less 
 completely occupied by a dense secondary deposit of scleren- 
 chyma. Moreover, when dissepiments are only present in 
 small number, and are at all exceptionally strong, it becomes 
 impossible to know whether one is dealing with structures of 
 this kind, or with that more developed stage of the same which 
 we know as “tabulae.” Upon the whole, however, we think 
 that the presence of ill-developed tabulae may be regarded as 
 the rule in the genus Lindstromia. In the annexed engraving 
 (fig. 4) we have represented vertical and transverse sections of 
 three forms of Lmdstromia upon an enlarged scale. 
 
8 4 
 
 ACTINOZOA. 
 
 Before leaving this subject, a few words may be said as 
 to the genus Petraia of Munster, merely in so far as the forms 
 at present under consideration are concerned. Palaeontolo- 
 gists have at various times included under the name of Petraia 
 
 Fig. 4. — a. Vertical section of Lindstromia ( Cyathaxonia ) Dalmani, Edw. and H., enlarged 
 two diameters, showing the dense infilling of the lower portion of the coral, the great 
 columella, and the transverse plates or tabulae ; a', Transverse section of the same, enlarged 
 three times, showing the dense central mass, and the almost complete amalgamation of 
 the septa by sclerenchyma. b, Vertical section of Lindstromia columnaris , Nich. and 
 Thoms., enlarged three times, showing the filled-up base, the composition of the colu- 
 mellar mass of partially amalgamated vertical rods, and the imperfect tabulae; b\ Trans- 
 verse section of the same, similarly enlarged, showing the fusion of the septa by means of 
 secondary sclerenchymatous deposit into a central columellar mass, c , VerticaFsection of 
 Lindstromia subduplicata , M‘Coy, sp., twice the natural size, showing the central fasciculate 
 columellar mass, the deep calice, and the imperfect tabulae ; c r , Cross-section of the same, 
 taken close to the base, enlarged five times, and showing the almost complete fusion of 
 the septa by secondary deposit. 
 
 a number of small, simple, turbinate corals, of very varying 
 structure, and, so far as known, of very different affinities ; 
 and perhaps the best course to adopt would be to entirely 
 drop this title from our nomenclature. If this course be not 
 followed, it will be necessary to restrict the name to some 
 
L INDS TROMIA. 
 
 «5 
 
 one or other of the various types of structure which have 
 been included under this name, since it does not appear to 
 be known what was the true nature of the fossils originally 
 placed here by Munster. From the definitions, however, of 
 all later observers, it is evident that the essential features in 
 the structure of Petraia are supposed to be the total want 
 of dissepiments , tabulcz , and columella , conjoined with the pres- 
 ence of well - developed lamellar septa and a deep funnel- 
 shaped calice. Our own personal investigations have not 
 brought under our notice any Palaeozoic corals in which we 
 could assert positively that these features are present. Two 
 or three small specimens from the curious fossiliferous ashes 
 of Balcletchie, near Girvan, certainly seem to want both tab- 
 ulae and dissepiments, and to otherwise conform to the above 
 definition ; but our material is so scanty that we have held 
 these forms over, in the hope of obtaining more light upon 
 this subject at a later date. On the other hand, we are 
 now able to speak positively as to the structure of at least 
 one of the most typical of M ‘Coy’s Petraice — viz., Petraia 
 subduplicata ; and we have been able to prove, as will sub- 
 sequently appear, that this is a true Lindstromia , which in 
 no way conforms to Petraia as ordinarily understood. The 
 determination of the real structure of this well-known Silurian 
 species may be regarded as probably settling the position of 
 at any rate most of the small corals included by Phillips under 
 the head of Ttir binolop sis (Pal. Foss, of Cornwall, &c., p. 1). 
 This name has been rightly regarded as a synonym of Petraia , 
 in the usual acceptation of the latter ; and it was founded, as is 
 the case with many species of Petraia , upon casts of the interior of 
 the corallum. These casts, as is well known, are abundant in the 
 Devonian and Silurian rocks, and they are remarkable, as has 
 been frequently noticed, for their being usually truncated below. 
 This truncation of the cast, as noticed by M‘Coy, is truly due 
 to the fact that the lower portion of the visceral chamber was 
 filled up with a dense secondary deposit of sclerenchyma, 
 this being one of the characteristic features of Lindstromia . 
 
86 
 
 ACTINOZOA. 
 
 In some cases, also, the lower end of the cast may be seen 
 to present a depression in the centre, corresponding with the 
 columella . 1 We need only add that it has seemed to us much 
 the most preferable course not to attempt to retain the generic 
 name of Petraia for P. subduplicata, M‘Coy, and for those other 
 forms which undoubtedly prove to be congeneric with this. It 
 is true that these forms constitute the most typical section of the 
 group which British palaeontologists have usually understood 
 by Petraia ; but it seems clear that the name Petraia cannot 
 be advantageously retained, unless it be strictly limited to 
 forms which want dissepiments, tabulae, and columella. Such 
 forms have been described (eg., P. Benediana , De Koninck) ; 
 but microscopic examination renders it certain that P. sub- 
 duplicata , IVTCoy, and its allies, must be placed in a totally 
 different category. 
 
 Lindstromia subduplicata, M‘Coy, sp. 
 
 (Fig. 4, and PL VI., figs. 2-2 f) 
 
 Petraia subduplicata , M‘Coy, Ann., and Mag. Nat. Hist., ser. 2, vol. vi. p. 
 2 79? 1850. 
 
 ,, „ M'Coy, Pal. Foss., p. 40, 1851. 
 
 „ „ Salter, Quart. Journ. Geol. Soc., vol. vii. p. 17 1, PI. IX., 
 
 figs. 7 and 8, 1851. 
 
 Spec. char. — Corallum simple, small, conical, straight or 
 slightly curved, averaging nine or ten lines in length, with 
 a diameter at the larger extremity of six or seven lines. 
 Epitheca well developed, marked with longitudinal ridges, 
 corresponding with the interseptal loculi, of which about four 
 occupy the space of one line. In well-preserved specimens 
 fine encircling striae are present as well, # and there are shallow 
 annulations of growth. The calice is deep, funnel-shaped, 
 and oblique. The septa are well developed and lamellar, 
 of two sizes, regularly alternating with one another, and vary- 
 ing from fifty to sixty in number in all. The secondary septa 
 
 1 This feature is sometimes very marked. Compare the figure of the cast of 
 Petraia elongata , Phill., given by Milne-Edwards and Haime in their Monograph 
 (Brit. Foss. Cor., PI. LX VI., figs. 6 and 6 a). 
 
LINDSTR 0M1A. 
 
 «7 
 
 are short, and, near the base of the coral, may be unrecog- 
 nisable. In the centre of the visceral chamber the primary 
 septa unite with one another, and become more or less com- 
 pletely fused together by the deposition of a mass of secondary 
 sclerenchyma, which more or less entirely fills up the lower 
 portion of the corallum. Superiorly the central mass formed 
 by the fusion of the inner ends of the septa, as afore-mentioned, 
 is continued upwards as a large pseudo-columella, which pro- 
 jects to a greater or less extent into the floor of the calice. 
 The interseptal loculi are crossed by a few remote and irregu- 
 larly-developed dissepiments, and a few imperfect tabulae can 
 be occasionally detected. No septal fossula. 
 
 Obs . — The Gray collection contains a large number of 
 specimens of this interesting little coral from the Craighead 
 limestone, in which the original skeleton of the coral is pre- 
 served, and from thin sections of which we have been able 
 to determine its structure in a satisfactory manner. Its general 
 form is conical and nearly straight, the attenuated tip of the 
 corallum being often slightly oblique, and its average dimen- 
 sions are as above stated. Many individuals, however, are much 
 smaller, and a few are larger. The epitheca is complete, with 
 well-marked longitudinal rugae, and, when perfectly preserved, 
 with close-set, fine, encircling striae. Annulations of growth, 
 though present, are never a marked feature. In all our sped- 
 
 fr 
 
 mens the calice is filled up with the matrix, but it is seen 
 in sections to be always deep, and more or less oblique, occu- 
 pying one-half to two-thirds of the entire length of the cor- 
 allum, the septa in its upper portion being merely marginal, 
 and gradually becoming more developed as we descend to- 
 wards the base. Longitudinal sections (fig. 4 c , and PI. VI., 
 figs. 2 b and 2 c) show the remarkable feature that the lower 
 third or thereabouts of the visceral chamber is filled up by 
 dense calcareous matter, which is really composed partly of the 
 primary septa, and partly of a secondary deposit of scleren- 
 chyma. In sections, taken accurately through the median 
 line, this calcareous infilling is seen to be prolonged upwards 
 
88 
 
 ACT1N0Z0A. 
 
 in the form of a large, apparently cylindrical pseudo-columella, 
 which projects to a greater or less extent above the floor of 
 the calice. In sections taken a little out of the median line, 
 this columellar mass shows its true composition by its exhib- 
 iting more or less distinctly the projection into the calice of 
 the cut edges of a number of the septa. The same fact can 
 also be determined by microscopic examination, which shows 
 that the essential elements of this mass are the inner ends 
 of the septa. As regards the other points shown by long 
 sections, we may notice the occasional occurrence of a few 
 strong transverse or ascending plates, which we must regard 
 as tabulae, and which are most conspicuous in excentric sec- 
 tions. Transverse sections, again, enable us to considerably 
 supplement the knowledge gained by means of vertical slices, 
 but they differ greatly according to the height above the base 
 at which they are taken. Sections taken close above the base 
 (fig. 4 c) show that the apparently structureless and dense 
 infilling of the lower part of the visceral chamber is really 
 formed largely out of the primary septa, the interseptal loculi 
 being occupied by a deposit of sclerenchyma, which is usually 
 so far imperfect as to leave small interspaces between the 
 outer ends of the septa. Sections taken at a higher level 
 (PI. VII., fig. 2 d) show the outer wall, the interseptal loculi, 
 which may or may not be crossed by a few dissepiments, 
 and a large central mass, which is formed by the union in 
 the median line of the primary septa, together with structure- 
 less calcareous matter of secondary origin. Sections taken 
 above the plane of the floor of the calice show the septa gradu- 
 ally to diminish in size, till they become almost obsolete. The 
 number of primary septa which take part in the formation 
 of the central pseudo -columella varies from twenty -five to 
 twenty-eight ; but between these there really exists a corre- 
 sponding number of much shorter secondary septa. These 
 latter, however, can often not be recognised — especially in 
 sections taken close above the base ; and even when present, 
 they may appear to be absent in a variable number of the 
 
LINDS TR OM I A . 
 
 89 
 
 interseptal loculi. Sometimes the development of the central 
 pseudo-columellar mass is decidedly excentric, but in no case 
 have we observed a regular septal fossula. As for tabulce , 
 they certainly are not present in a well-marked form. Longi- 
 tudinal sections, however, often show — especially if excentric 
 — ascending transverse plates, which we consider to be unques- 
 tionably imperfect structures of this nature. 
 
 Casts of Lindstromia subduplicata are not uncommon in the 
 sandstones of Mulloch Hill, near Girvan, and their characters 
 have been well described by M‘Coy. As we can readily see 
 from the structure of the corallum, as we now know it, these 
 casts represent the filled-up vacuities of the upper portion of 
 the corallum only. The cast is conical, truncated behind, of 
 nearly equal width and length, marked externally with from 
 twenty-four to thirty-two deep slits, which extend to near the 
 centre, where they are slightly twisted. These slits represent 
 the primary septa, and they are separated by an equal number 
 of finer slits, which only extend a very short distance inwards, 
 and which represent the short secondary septa. The radiating 
 lamellae of the cast, which separate and bound these slits, repre- 
 sent, of course, the filled-up interseptal loculi. The introduc- 
 tion of new septa was effected along the line of a principal 
 interseptal space occupying the dorsal side of the corallum, 
 giving rise to a pinnate arrangement of the sulci in the cast. 
 We have also evidence that the septa within the calice were 
 more or less markedly crenulated, ridged, or toothed on their 
 sides. This is shown by the occurrence of grooves or pits 
 upon the sides of the lamellae which represent the filled-up 
 interseptal loculi. In ordinary casts, this crenulation of the 
 upper portions of the lamellae just alluded to is not a marked 
 feature, though usually to be detected with care. There are, 
 however, other casts (PL VI., fig. 2 f) in which the crenulation 
 of the upper parts of the lamellae is extraordinarily conspicuous, 
 the outer edge of each being cut into prominent teeth by deep 
 and regular lateral grooves. These casts have been described 
 and figured by M‘Coy (Pal. Foss., p. 41, PI. I. B, fig. 26 b), 
 
9 ° 
 
 ACTINOZOA. 
 
 and they are regarded by him, probably quite rightly, as 
 merely a variety of L. subduplicata , to which he gives the 
 title of crenulata . 
 
 Form . and Loc . — Common in the shales associated with the 
 limestone at Craighead, near Girvan (Lower Silurian). Also 
 not uncommon, though principally in the condition of casts, in 
 the mudstones of Mulloch Hill, near Girvan, of Upper Silurian 
 (? Upper Llandovery) age. A few individuals from the green- 
 ish mudstones of Penkill, near Girvan (? Upper Llandovery), 
 also appear to belong to this species, though we have not 
 examined them microscopically. (Gray collection.) 
 
 Lindstromia lsevis, Nich. and Eth., jun., sp. nov. 
 
 (PL VI, figs. 4-4 e.) 
 
 Spec. char . — Corallum small, simple, expanding, and widely 
 turbinate, slightly curved towards its smaller extremity. The 
 width of the calice equal to or slightly larger than the total 
 length of the corallum. Surface to the naked eye nearly or 
 quite smooth, under the lens exhibiting fine and close-set en- 
 circling striae, and obscure longitudinal ridges. Epitheca com- 
 plete ; wall thick. Generally one or two shallow annulations 
 of growth near the calicine margin. Calice oblique, patulous, 
 its interior unknown, but always deep, and having the septa 
 obsolete, or nearly so, near its lip. From fifteen to twenty- 
 three primary septa, at various diameters, becoming more or 
 less united with one another below the floor of the calice, and 
 fused by means of a secondary deposit of sclerenchyma, so as to 
 form a central pseudo-columellar mass of large size, which pro- 
 jects to a greater or less extent into the bottom of the calice. 
 Short secondary septa are probably present between the pri- 
 mary ones, but they have not been determined with certainty. 
 Dissepiments unknown. Tabulae apparently represented by 
 a few remote and strong arched and ascending plates, which 
 intersect the visceral chamber near the base, and take part in 
 the formation of the pseudo-columella. 
 
L JNDSTR OMIA . 
 
 9 l 
 
 The smallest individuals observed are a line and a half long, 
 with a width at the calice of a line and three quarters. 
 Average examples are three lines long, and three and a half 
 lines in their greatest diameter. Large individuals attain a 
 length of six lines, with a calicine diameter of between six and 
 seven lines. 
 
 Obs. — This pretty little species is abundant and well pre- 
 served in the mudstones of Penkill, near Girvan. It is by no 
 means impossible that it may turn out to be really identical 
 with Petr diet uniserialis , M‘Coy (Pal. Foss., p. 41, PI. I. B, fig. 
 25); but as the latter is known only by casts, as our form is 
 known only by the external and internal characters of the cor- 
 allum itself, and as we have no means of connecting the two, 
 we have thought it best to establish a new species for our 
 examples. The external characters of Lindstromia Icevis are 
 very readily recognisable, and distinguish it at once from L. 
 subduplicata, M‘Coy. It is at once known by its short, curved, 
 and very widely expanding corallum, and the apparent smooth- 
 ness of the epitheca, the use of a lens at once showing that the 
 surface is really covered with very fine and closely-arranged 
 concentric striae. Longitudinal ridges and annulations of 
 growth are faintly marked or nearly obsolete. The calice is 
 oblique, though not so markedly so as in L. subduplicata ; but 
 owing to the fact that it is filled up with the matrix in all our 
 specimens, we can say nothing as to the condition of its interior. 
 Long sections, however, show that it is deep and funnel-shaped, 
 and the septa are also merely marginal ridges near its imme- 
 diate lip. 
 
 As the corallum itself is preserved, thin sections enable us to 
 study its internal structure quite satisfactorily, and it can be 
 shown in this way to be a true Lindstromia , with closer affini- 
 ties to L. ( Cyathaxonia ) Dalmani , E. and H., than is the case 
 with L . subduplicata , M‘Coy. Cross-sections, taken below the 
 level of the calice, show that most or all of the primary septa 
 become coalescent and embedded in secondary sclerenchy- 
 matous deposit, thus forming a comparatively immense pseudo- 
 
9 2 
 
 ACTINOZOA. 
 
 columellar mass, which, in long sections, can be shown to 
 project to a considerable height into the calice. We can also 
 detect in vertical slices a few strong and arched transverse or 
 ascending plates, which must be regarded as tabulae, and which 
 join the columella centrally. There are two points which we 
 have been unable to determine with certainty — namely, the 
 existence of dissepiments and of short secondary septa. There 
 are indications of both, and, from the analogy of the other 
 species of the genus, we may conclude that these structures 
 were really present. That we should not have been able to 
 detect them is probably due to the fact that the cavities of the 
 wide and patulous corallum are generally filled with the matrix, 
 fine structures being thus broken down, and microscopic ex- 
 amination considerably interfered with. The extreme base of 
 the corallum is more or less completely solidified by a dense 
 deposit of the sclerenchyma, though this is not so largely de- 
 veloped as in L. subduplicata , M‘Coy. 
 
 Form, and Loc . — Common in the greenish mudstones (? Upper 
 Llandovery) of Penkill, near Girvan. (Gray collection.) 
 
 GENERAL REMARKS UPON THE CORALS OF 
 THE GIRVAN AREA. 
 
 Though we have now examined a very large number of 
 corals from the Silurian rocks of the Girvan district, it remains 
 clear that the materials at present to hand will be very con- 
 siderably augmented by future researches. Up to this time, in 
 fact, corals have been collected almost exclusively from some 
 three or four horizons in the great and complicated series of 
 the Ayrshire Silurians. Much, therefore, has yet to be done, 
 as will be seen by a glance at the list of localities previously 
 given, before we can give any complete conspectus of the coral- 
 fauna of this region ; and the time has not come at which it will 
 be possible to enunciate positive conclusions as to the age of 
 the deposits from fossils of this class. Nevertheless it may 
 
GENERAL REMARKS. 
 
 9 $ 
 
 be of advantage that we should make a few remarks as to the 
 distribution and time-relations of the known corals of the region 
 in question ; and we may conveniently do so by reviewing 
 briefly the chief horizons which, so far, have proved to be 
 coralliferous. 
 
 I. The Craighead Limestone. — Up to the present time, 
 the principal Silurian deposit in Ayrshire from which corals 
 have been collected is the great limestone, which is best known 
 as exposed in the quarries at Craighead, about three miles from 
 the town of Girvan. As here seen, the limestone itself is gen- 
 erally more or less grey in colour, and compact or sub-crystal- 
 line in texture, but it varies much in different parts of its mass. 
 Often it is greenish in colour, or mottled with lighter or darker 
 green blotches, apparently from the presence of felspathic or 
 serpentinous matter intimately mingled with it ; and occasion- 
 ally a well-marked oolitic structure is developed in it. This 
 last feature, however, is much more conspicuous in the Tra- 
 mitchell quarries, where the limestone is to a large extent a 
 regular oolite, the component grains being of considerable size. 
 Associated with the limestone at Craighead are also greenish 
 shales, which have yielded a considerable number of fossils. 
 Leaving out of sight some forms which our material has not 
 allowed us to work out, the corals of the Craighead limestone 
 and its associated shales, as. at present known to us, are as 
 follows : — 
 
 Lyopora favosa , M‘Coy, sp. 
 
 Tetradium Peachii , Nich. and Eth., jun. 
 Favosiies Girvanensis , Nich. and Eth., jun. 
 Fistulipora ? pilula , Nich. and Eth., jun. 
 Prasopora Grayed, Nich. and Eth., jun. 
 Thecostegites ? Scoticus , Nich. and Eth., jun. 
 Heliolites Grayi , Edw. and Haime. 
 
 Stylarcea occidentalism Nich. and Eth., jun. 
 Streptelasma Craigense , M‘Coy, sp. 
 
 „ Europceum, Ferd. Roemer. 
 
 „ aggregation , Nich. ahd Eth., jun. 
 Lindstromia subduplicata , M‘Coy, sp. 
 
94 
 
 ACTJNOZOA. 
 
 So far as giving us a clue to the precise position in the 
 Silurian series occupied by the Craighead limestone, the 
 above twelve corals are clearly of limited value. The entire 
 assemblage — which we feel certain will hereafter be con- 
 siderably increased — is a most remarkable one, and admits of 
 little comparison with the coral-fauna of any sub-group of the 
 Silurian rocks known to us. Lyopora favosa , Tetradium 
 Peachii , Prasopora Grayce , Streptelasma Craigense , S'. Euro- 
 pceum , S', aggregation , and Lindstromia sub dup lie at a, are the 
 common forms of the Craighead limestone ; and, with the 
 exception of the last, they are not known to occur else- 
 where in Britain. Moreover, Lyopora and Prasopora are 
 special generic types, and Streptelasma and Tetradium have 
 not been previously recognised in this country, though the 
 former, at any rate, will doubtless be found to have a wide 
 range. Of the remaining forms, Stylarcea occidentalis and 
 Thecostegites (?) Scoticus both belong to generic types foreign 
 to Britain, though the identification of the latter cannot be 
 regarded as certain. Lastly, the only specific forms which 
 are known to occur elsewhere in the British area are Lind- 
 stromia subduplicata , M‘Coy, and Heliolites Grayi , Edw. and 
 H., both of which occur in undoubted Upper Silurian deposits 
 elsewhere. 
 
 That the Craighead limestone, however, is not of Upper 
 Silurian age, may be considered as certain. The absence of 
 the commoner massive species of Favosites } Alveolites , and 
 Heliolites , of Cyathophyllum , Acervularia , Cystiphyllum , Haly- 
 sites, and Omphyma , together with the apparent total want of 
 Stromatoporoids, would render this conclusion almost inevit- 
 able, even if we had nothing else to go by. The genera Tetra- 
 dium , Stylarcea , and Streptelasma are, however, characteristi- 
 cally, or exclusively, found in deposits belonging to the Lower 
 Silurian period. We also cannot avoid being greatly struck 
 
 1 The Favosites Gi-rvanensis of the Craighead limestone is a very diminutive form, 
 and is a poor representative of the large and common F. Gothlandica, F. Forbesi , 
 &c., of the Upper Silurian. 
 
GENERAL REMARKS. 
 
 95 
 
 with the strongly American facies of the Craighead corals, and 
 in particular their resemblance to those of the Trenton and 
 Cincinnati groups. Thus Tetradium x is a common generic 
 type in the Trenton limestone and Cincinnati formation in both 
 the United States and Canada. Streptelasma Europceum is a 
 close ally of the common Streptelasma corniculum of the same 
 deposits. Our Streptelasma aggregatum belongs to the sub- 
 generic group Palczophyllum, the only other members of which 
 are found in the Trenton and Cincinnati formations. Stylarcea 
 occidentalis may be taken as representative of the common 
 Protarcea vetitsta of the Cincinnati beds. Lastly, the nearest 
 allies to the curious Lyopora favosa of Craighead are to be 
 found in the so-called Columnaricz (not Favistella , Hall) of the 
 Trenton limestone, and especially in such forms as C. Goldftissi , 
 Bill. Upon the whole, therefore, we must conclude that the 
 Craighead limestone is certainly of Lower Silurian age ; and, 
 if we judge only from the corals, we are led to conjecture that 
 it occupies a tolerably low position in the Lower Silurian series, 
 corresponding perhaps with the upper part of the Trenton 
 limestone, or the base of the Cincinnati and Hudson River 
 formations of North America. 
 
 II. Mulloch Hill Beds.— Mulloch Hill, near Dalquharran, 
 has long been known as one of the most prolific localities for 
 fossils in the Girvan district. M‘Coy generally speaks of the 
 rock here as a “ quartzite ” or “ sandstone,” but it contains no 
 silica. It is a hard greenish mudstone, the colour of which, as 
 seen in thin sections, appears to be due to the presence of 
 numerous particles of serpentinous or felspathic matter. Owing 
 to the absence of lime in these deposits, corals are, naturally, 
 not abundant, and they occur commonly, though by no means 
 exclusively, in the condition of casts. Disregarding two or 
 three forms, which could not be determined with the material 
 
 1 Since the above was written, our friend George J. Hinde, Esq., F.G.S., has 
 shown us specimens which he has collected in the Trenton Limestone of Canada, 
 which, so far as we can judge without microscopic sections, are specifically identical 
 with our Tetradiurn Peachii. 
 
9 6 
 
 ACTINOZOA. 
 
 at our command, we have recognised the following four corals 
 in the Mulloch Hill beds : — 
 
 Ileliolites interstincta , Wahl. 
 
 Pinacopora Grayi , Nich. and Eth., jun. 
 
 Favosites Mullochensis , Nich. and Eth., jun. 
 
 Liiidstromia subduplicata , M‘Coy, sp. 
 
 The last-named of the above is no test of age, as it occurs 
 in rocks belonging to different periods ; and Pinacopora Grayi , 
 being both generically and specifically new, is also unavailable 
 as a guide. The presence of Heliolites interstincta , however, 
 together with a large-celled Favosites of the type of F. Gothlan- 
 dica and F. Forbesi , would lead to the conclusion that the Mul- 
 loch Hill beds are certainly referable to the Upper Silurian. 
 This conclusion is borne out by the nature of the associated 
 fossils ; and we may in the meanwhile consider this deposit as 
 probably corresponding with the Upper Llandovery or May 
 Hill sandstone of “ Siluria.” 
 
 III. Penkill Beds. — The rocks at Penkill, near Girvan, 
 from which we possess corals, consist of a fine-grained grey or 
 greenish-grey mudstone, and the number of corals is limited. 
 From this horizon we have determined the following : — 
 
 Heliolites interstincta , Wahl. 
 
 Haly sites catenularia , Linn. 
 
 Favosites Girvanensis , Nich. and Eth., jun. 
 
 Liiidstromia subduplicata , M‘Coy, sp. 
 
 „ Levis, Nich. and Eth., jun. 
 
 Calostylis Lindstromi , Nich. and Eth., jun. 
 
 The only species in this list which can be used as tests of 
 age are Heliolites interstincta and Halysites catenularia , and 
 these would go to prove that the beds here are of Upper 
 Silurian age. The singular Perforate genus Calostylis , Lindstr., 
 is likewise an Upper Silurian type, the only other known spe- 
 cies of the genus being confined to the Wenlock limestone of 
 Gotland. Such other evidence as we have points in the same 
 direction, and we are probably right in concluding that the Pen- 
 
GENERAL REMARKS. 
 
 97 
 
 kill beds must find their place towards the lower portion of the 
 Upper Silurian series. 
 
 IV. Shallocii Mill Beds. — We are indebted to Mr Lap- 
 worth for specimens from a thin band of coralline limestone 
 which crops out on the sea-shore, near a smithy not far from 
 Shalloch Mill, about a mile and a quarter to the south of 
 Girvan. The fossils appear to be tolerably plentiful, but they 
 consist wholly of Favosites Gothlandica , Lam., and Alveolites 
 Labechei , Edw. and H. The presence of these two well- 
 known types would render it certain that the series of beds in 
 which this limestone is intercalated must be of Upper Silurian 
 age. Further along the shore, in beds considerably higher in 
 position, Mr Lapworth has also detected the presence in calca- 
 reous nodules or “ cement-stones ” of Haly sites catenularia. 
 
 V. Balcletchie Beds. — The last coralliferous horizon 
 which we need notice is that of the Balcletchie beds, near 
 Girvan. The beds in question, which are not the same as 
 those from which we possess remains of Trilobites, consist 
 of dark-green, coarse-grained volcanic ashes, and appear to 
 be largely fossiliferous. The corals are few in number, 
 and badly preserved ; and the only form that we have 
 been able to determine positively is Fistulipora favosa, nobis. 
 We have also several small cup-corals, very fairly preserved, 
 but our material is insufficient to allow of a thorough examina- 
 tion of these. There are two or three types, and one of them 
 seems to conform to the definition of Petraia , which we have 
 given in speaking of Lindsti'oinia — that is to say, its interseptal 
 loculi are open, and it shows no traces of dissepiments, tabulae, 
 or columella. It is much to be desired, however, that further 
 collections should be made from this locality. The corals give 
 us no clue to the age of the Balcletchie beds, but there is some 
 reason to believe that they are low down in the Lower Silurian 
 series — possibly near the horizon of the Craighead Limestone. 
 
 G 
 
9 8 
 
 TR I LOB IT A. 
 
 SUB-KINGDOM ANN U LOS A. 
 CLASS CRUSTACEA. 
 
 Sub-class Entomostraca. 
 Order TRILOBITA. 
 
 Genus Phacops, Emmrich, 1839. 
 
 (De Trilobitis, &c., p. 18.) 
 
 Section Phacops proper. 
 
 Phacops Stokesii, Milne-Edwards. 
 
 P. Stokesii (M.-Edwards), Salter, Mon. Brit. Trilobites, 1864, pt. 1, p. 21, 
 t. 2, f. 1-6 ( for synonomy). 
 
 „ ,, Salter, Murchison’s Siluria, 1867, 4th ed., t. 10, f. 6, t. 18, f. 6. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 64. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 54. 
 
 Obs. — P. Stokesii was long ago recorded 1 as a Girvan species 
 by the late Mr J. W. Salter, and a head and tail figured in the 
 Appendix to Sir R. I. Murchison’s paper “ On the Silurian 
 Rocks of the South of Scotland.” We have not met with 
 specimens. 
 
 Loc. and Horizon. — Mulloch Quarry, in shelly sandstone 
 (Salter). Saugh Hill, in sandstone (Salter). Thrave . 2 
 
 Phacops Downingice is stated to occur at Mulloch 'Quarry , 3 
 but we believe the next species has been mistaken for it. 
 
 1 Quart. Jour. Geol. Soc., 1851, vii. pp. 171, 172. 
 
 2 Cat. Foss. Mus. Pract. Geology, 1865, p. 12. 
 
 3 Cat. W. Scot. Foss... 1876. p. 16. 
 
PHACOPS. 
 
 99 
 
 Section Acaste, Goldfuss. 
 
 Phacops Brongniarti, Portlock. 
 
 (PI. VII. figs, i and 2.) 
 
 P. { Acaste ) Brongniarti (Portlock), Salter, Mon. Brit. Trilob ites, 1864, pt. 1, 
 p. 34, t. 1, f. 20-25 ( for synonomy). 
 
 P. Brongniarti , Bigsby, Thesaurus Sil., 1868, p. 62. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 50. 
 
 Obs. — After Mr Salter’s clear and detailed description it is 
 quite unnecessary for us to redescribe P. Brongniarti , which 
 with its var. Dalmani was first met with in the Girvan district 
 by the late Mr R. Gibbs, and determined by Mr R. Etheridge, 
 F.R.S . 1 We give a figure taken from a cast of an exceedingly 
 well-preserved mould in the Museum of Practical Geology ; 
 we are indebted to the authorities of that institution for the 
 loan of it. 
 
 Loc . and Horizon. — Ardmillan-brae, in flagstones {Etheridge ) ; 
 Mulloch Hill quarry. (Gray Collection.) 
 
 Section Chasmops, M ( Coy. 
 
 Phacops truncato-caudatus, Portlock (?). 
 
 (PI. VII. figs. 3 and 4.) 
 
 P. {Chasmops) truncato-caudatus (Portlock), Salter, Mon. Brit. Trilobites, 1864, 
 
 pt. 1, p. 42, t. 4, f. 13-15 {for synonomy). 
 
 P. truncato-caudatus , Bigsby, Thesaurus Sil., 1868, p. 64. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 54. 
 
 Obs . — Our specimens are both unfortunately imperfect about 
 the head, which necessitates a note of interrogation after the 
 name of the species ; otherwise, however, the* characters of the 
 specimens appear to accord perfectly with those given by Mr 
 Salter as distinctive of the species. The sides of the axis of 
 the thorax are conspicuously nodose, the axal furrows strong, 
 and there is a strong node on the inner end of each pleura 
 against the axis, a character upon which stress is laid by Mr 
 Salter. Now these are all present in the specimens we refer 
 
 Mem. Geol. Survey. Scot. Expl., No. 7, 1869, p. 10. 
 
IOO 
 
 TR 1 LOBITA . 
 
 to P. truncato-caudatus ; and in the absence of more negative 
 evidence, we believe we are justified in referring them to 
 that species. Moreover, one of the specimens shows that the 
 head was granulated ; and if we refer to Portlock’s original 
 figures, 1 we see a peculiar cross-puckering of the surface rep- 
 resented by vertical shading, a point exceedingly well marked 
 in the Girvan individuals. In the determination of the latter 
 we are happy to possess the support of Mr Etheridge, F.R.S. 
 We think our specimens hardly possess as many segments in 
 the pygidium as those figured by Mr Salter. 
 
 Loc . and Horizon. — Drummuck Quarry, in a compact 
 greenish mudstone. (Gray collection.) 
 
 Genus Cheirurus, Beyrich, 1845. 
 
 (Ueber einige bohmische Trilobiten, p. 5.) 
 
 Cheirurus bimucronatus, Murchison. 
 
 C. bimucronatus (Murch.), Salter, Mon. Brit. Trilobites, 1864, pt. 1, p. 63, 
 t. 5, f. 1-5, t. 6, f. 9-18 {for synonomy). 
 
 ,, „ Bigsby, Thesaurus Sil., 1868, p. 44. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 30. 
 
 05 s. — This species has been twice recorded by the late Mr 
 Salter 2 as occurring at Girvan ; but we have not seen speci- 
 mens in any of the collections to which we have had access. 
 We can only refer to its occurrence there, and hope that future 
 observers will be more fortunate. 
 
 Loc. and Horizon. — Drummuck Quarry, in shaly beds ; Mul- 
 loch Hill {Salter). 
 
 Cheirurus gelasinosus, Portlock. 
 
 (PI. VII. figs. 5 and 6.) 
 
 C. gelasinosus (Portlock), Salter, Mon. Brit. Trilobites, 1864, pt. 1, p. 71, t. 5, 
 f. 6-8 ( for synonomy ). 
 
 ,, „ Bigsby, Thesaurus Sil., 1868, p. 44. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 30. 
 
 Obs . — The specimens before us do not throw any further 
 
 1 Geol. Report on Londonderry, &c., 1843, t* 2 > f* I_ 4- 
 
 2 Quart. Jour. Geol. Soc., 1851, vii. p. 172; Monograph, p. 67. 
 
C HEIR UR US. 
 
 IOI 
 
 light oil the structure of this species, and as they are only badly 
 preserved portions of the head, we refer the reader to Salters 
 description. Our chief reason for placing these fragments in 
 this species rather than with C. bimucroncttus , is the form of the 
 forehead lobe of the glabella, which is about equal in breadth 
 to the others, no wider, and does not overhang the other lobes 
 on the sides, and in front is not produced, and, lastly, does not 
 occupy all the margin, as in C. bimucronatus . The specimens 
 are small, and in an unsatisfactory state of preservation, and 
 further material is required for proper elucidation. We find 
 C. gelasinosus was first mentioned as occurring at Girvan by 
 Mr Salter, 1 who figured a portion of a fine head from that 
 district. 
 
 Loc. a7id Horizon. — Craighead Quarry, in limestone (Salter, 
 Mus. Pract. Geol.) ; Balcletchie, in a dark-green, slightly cal- 
 careous mudstone. (Gray collection.) 
 
 Cheirnrus clavifrons, Dalman ? 
 
 (PI. VII. figs. 7 and 8.) 
 
 Calymene (?) clavifrons , Dalman, Vet. Akad. Handlingar, 1826, p. 260. 
 
 „ ,, Dalman, Om. Palaeaderna eller de sa Kallade Trilo- 
 
 biterna, 1827, p. 75 ( separate copies). 
 
 „ ,, Loven, Ofv. K. Vet. Akad. Forhandlingar, 1844, No. 
 
 4, p. 63. 
 
 Cyrlometopus ajfinis, Angelin, Pal. Scandinavica, 1854, pt. 1, p. 7 7, t. 39, f. 10. 
 
 (Compare Cheirnrus octolobatus (M‘Coy), Salter, Mon. Brit. Trilobites, 1864, 
 pt. 1, p. 69, t. 5, f. 13 and 14.) 
 
 Spec. char. — Glabella oval-oblong, blunt in front, regularly 
 convex, most so in a line drawn across uniting the two foremost 
 furrows — it is also broader at this point, slopes gradually off to 
 the neck segment, and does not overhang the front margin. 
 Frontal and ocular furrows moderately long and curved slightly 
 backwards ; basal furrows circumscribing the oval basal lobes, 
 but faintly marked where they join the neck segment, otherwise 
 they, and the frontal and ocular furrows, are deep ; the distance 
 
 1 Quart. Jour. Geol. Soc., 1851, vii. p. 170, t. 8, f. 1 ; Mems. Geol. Survey, Dec. 
 vii., No. ii., p. 11 ; Monograph, p. 72. 
 
102 
 
 TRILOBITA. 
 
 between the ocular and basal furrows, on the one hand, and the 
 ocular and frontals on the other, is about equal ; the surface is 
 microscopically granular. The fixed cheeks are rudely triangu- 
 lar, scrobiculate, and, like the glabella, microscopically granular 
 or roughened ; although not vertical, they are steeply inclined. 
 Facial suture strongly marked, and in the first part of its course, 
 starting from the external margin, is almost on a line with the 
 ocular furrow. Frontal margin broad and distinct; axal furrows 
 broad, deep, and well marked. 
 
 Obs. — The specimen we figure under this name, a glabella 
 and one fixed cheek, has given us much trouble ; neither do we 
 yet feel satisfied that it is C. clavifrons , Dalman. This difficulty 
 has arisen in a great measure from the want of a clear defini- 
 tion of what is C. clavifrons , Dal., accompanied by a good figure. 
 It appears, from Angelin 1 and Salter’s 2 account, that two dis- 
 tinct species were included by Dalman under this name, and 
 placed in the Stockholm Museum : one of these has a narrow- 
 fronted glabella, with parallel sides , 3 and for this Angelin re- 
 tained the name C . clavifrons ; the other, with a sub-clavate 
 glabella, is more deserving of the name bestowed by Dalman. 
 This, Professor Angelin has called Cyrtornetoptis ajfinisP Had 
 the name clavifrons been retained for the latter instead of the 
 former, much confusion would have been prevented ; and we 
 quite agree with Salter’s opinion — “We shall never have done 
 with the confusion of these forms unless we restrict Dalman’s 
 name to the species called Cyr. ajfnis by Angelin .” 5 Taking, 
 therefore, C. clavifrons , Dal., as typified by Cyrtometopus ajfnis, 
 Angelin, we may institute as close a comparison with our fig- 
 ured specimen as the side view of the head given by Angelin 
 will permit. The form of the glabella in the two individuals 
 is very much the same ; in both, the basal lobe is completely 
 circumscribed by the furrow ; but in Angelin’s figure the two 
 anterior furrows are shorter than in the Girvan specimen. So 
 far as the fixed cheek is preserved in the latter, there is a close 
 
 1 Pal. Scand., p. 78. 2 Monograph, pt. 1, p. 68. 3 Pal. Scand., t. 39, f. 9. 
 
 4 Pal. Scand., t. 39, f. 10. 5 Monograph, pt. 1, p. 68. 
 
CIIEIR UR US. 
 
 103 
 
 correspondence between the two ; they are both scrobiculate ; 
 the position of the eye is much the same ; and lastly, the facial 
 suture, after leaving the external margin, proceeds in a direct 
 line with the ocular furrow before turning off round the eye — 
 a most important point of resemblance. 
 
 Amongst recognised British forms, we have to compare our 
 specimen with C. octolobatus (M‘Coy), Salter, and C. juvenis , 
 Salter. Its resemblance to the former is, in some points, very 
 striking : for instance, the circumscription of the basal lobes, 
 length and direction of the ocular and frontal furrows, and 
 form of the fixed cheeks, are similar ; whilst, on the other hand, 
 the elevation of the glabella above the front margin and the 
 neck segment are not marked in our specimen as in C. octolo- 
 batus — neither does the glabella overhang the front margin. 
 The form and ornamentation of the fixed cheeks is similar ; and 
 the facial suture, as in Angelin’s figure, is directed towards the 
 ocular furrow. On the whole, there appears to be such a dove- 
 tailing of characters between our Girvan form, Cyrtometopus 
 affinis , Angelin, and C. octolobatus , M‘Coy, as to strongly bear 
 out Salter’s view that the latter “ will have to forego its bap- 
 tismal privileges ; ” 1 and again, “ our British name must give 
 way to the prior one, for it seems to be really the long-contested 
 C. clavifrons of Dalman /’ 2 
 
 With regard to C. affinis , Salter , 3 the task of comparison is 
 much easier : we have only to look at the position of the facial 
 suture of this species in regard to its position with the ocular 
 furrow, to see at once that it is quite distinct from the Girvan 
 form. In C. affinis it is directed in a line with the basal instead 
 of the ocular furrow, as in the others ; although, so far as the 
 form of the glabella only is concerned, that of C. affinis is per- 
 haps more in accord with the Girvan specimen than are either 
 C. clavifrons , Dal., or C. octolobatus (M‘Coy), Salter. 
 
 The species now under consideration resembles C. neglectus , 
 Barr , 4 but the form of the cheeks in the latter will enable the 
 
 1 Monograph, pt. 1, p. 68. 2 Ibid., p. 70. 3 Ibid., t. 5, f. 9-12 (especially f. 11). 
 
 4 Syst. Sil. Boh. Atlas, I., t. 40, f. 20 and 21. 
 
104 
 
 TR I LOB IT A. 
 
 two species to be distinguished. The form of the glabella and 
 the very restricted circumscribed lobes in C. gryphus , Barr, 1 at 
 once distinguish the latter from our C. clavifrons (?). A close 
 comparison should also be instituted with C. pectinifer, Barr ; 2 
 but it appears to us that the glabella of the latter is relatively 
 too depressed. 
 
 In well-marked internal casts the basal lobes are found to be 
 quite circumscribed ; but in examples with the whole of the 
 integument preserved, the basal furrows on nearing the neck 
 furrow become much shallower, and in a specimen here and 
 there would lead to the belief that they did not quite cir- 
 cumscribe the lobe. 
 
 We were at first inclined to regard the subject of fig. 9, PI. 
 VII., as distinct from C. clavifrons , Dal. (?). The specimen in 
 question is certainly more depressed, and a little more acute 
 in front ; but the chief point of difference appeared to us to lie 
 in the ornamentation — a microscopically granular surface with 
 scattered pimples, prickles, or small tubercules. However, a 
 further series of specimens has revealed to us the fact that 
 the convexity of the glabella varies considerably ; and one 
 particularly good example, which we hope to figure in our 
 second Fasciculus, shows an outer surface as described in 
 our specific diagnosis, underlaid by a layer with the characters 
 represented by fig. 9, PL VII., and just described. We hope 
 to return to this subject at a later period. 
 
 Loc. and Horizon. — Drummuck, in a fine-grained mudstone 
 (Gray collection). Thrave Glen, in a buff-coloured rock (Gray 
 collection). Penwhapple, in greenish sandstone (Salter? Coll. 
 Brit. Mus., as C. octolobatus ). C. clavifroits appears to have been 
 first recorded as a Girvan fossil by Messrs Armstrong, Young, 
 and Robertson; 4 if, however, C. octolobatus is identical, Dr H. 
 Woodward first determined its existence in those rocks. 
 
 1 Loc cit ., Supp. I., t. 3, f. 10-17. 2 Loc tit., t. 4, f. 16. 
 
 3 Salter, Monograph, p. 70. 4 Cat. W. Scot. Foss., 1876, p. 15. 
 
CJIEIRURUS. 
 
 IO: 
 
 Cheirurus trispinosus, Young. 
 
 (PL VII., figs. 10-17.) 
 
 C. trispinosus , Young, Proc. Nat. Hist. Soc. Glasgow, 1868, i., pt. 1, pp. 
 169-171, t. 1, f. 4, 6 b. 
 
 „ „ Etheridge, jun., Proc. R. Phys. Soc. Edinb., 1878, iv., pt. 3, p. 
 
 i 73 - 
 
 Sp. char . — General form of the head probably semicircular ; 
 free cheek semilunate-triangular, with a rounded, broad, and 
 
 entire free margin. Eye ? Facial suture cutting the outer 
 
 margin in a line with the basal furrows of the glabella. Neck 
 furrow deep and well marked. Glabella globular convex, dip- 
 ping little towards the neck furrow, vertical and blunt in front, 
 or slightly overhanging ; frontal furrows short, shallow, some- 
 times quite inconspicuous and far forward ; middle or ocular 
 furrows longer than the frontal, more strongly marked, and 
 inclined backwards ; basal furrows the most conspicuous of all, 
 deep, and curving inwards and backwards, uniting with the 
 neck furrow, but faint at the point of union, enclosing prom- 
 inent, well-marked basal lobes, bearing between them in the 
 middle line a narrow neck. The fixed cheeks are equal in 
 antero-posterior dimensions to the basal and cervical lobes ; 
 the anterior margins in a line with the posterior of the three 
 furrows, and the gently arched surface well marked off from 
 the prominent glabella by a slight longitudinal depression ; the 
 outer margins are not straight, but bend slightly inwards pos- 
 teriorly, the greatest width is therefore where they join with 
 the free cheeks ; the posterior margins of the fixed cheeks 
 slope obliquely outwards and backwards to the angles. The 
 posterior angles are produced into long, tapering, genal spines, 
 with a dorsal curvature, the apices not descending below the 
 general level of the body. The neck lobe is prominent, thick- 
 ened, and produced into a strong median spine curved in a 
 similar manner to the others. The glabella, fixed and free 
 cheeks, and the bases of the spines, are covered with large, 
 coarse, and elongated tubercules, intermingled with finer ones, 
 
io6 
 
 TRILOBITA . 
 
 and scattered without arrangement. The apices of the spines 
 are delicately striate. 
 
 Obs. — After a lapse of nearly ten years since its original 
 description by Prof J. Young, M.D., we are able to add very 
 little to the account of this interesting Trilobite. So far only 
 the head of C. trispinosns has come to light, and, even in the 
 case of specimens of this, always in a mutilated condition. 
 The individuals present in the Gray Collection appear to 
 exhibit the genal and cervical spines in a more satisfactory 
 manner than those from which Prof. Young’s description was 
 made, now in the Hunterian Museum, Glasgow. In drawing 
 up the above specific diagnosis we have availed ourselves of 
 Prof. Young’s description, and we have reproduced his outline 
 drawing of the restored carapace (fig. 1 7). 
 
 C. trispinosus has the thickened neck segment seen in many 
 species of the genus, and appears to be peculiar, so far as we 
 have been able to ascertain from a comparison with a large 
 mimber of specimens and figures, in the presence of the cervical 
 spine, as Prof. Young originally pointed out. Many Cheiruri , 
 as for instance C. insignis , Beyrich, C. gibbus , Beyrich, and C. 
 ornatus , Dalman, have a small tubercule in the centre of the 
 neck lobe, more or less developed according to species : may 
 the cervical spine of C. trispinosus be a further development of 
 this ? Again, in some American species there is a median 
 cephalic spine developed, as C. Satynts , Billings, and C. 
 glaucus, Billings, 1 but it arises from the posterior median 
 portion of the glabella, and not from the neck lobe. Although 
 placed in Cheirurus , Prof. Young remarks that it may “here- 
 after be found to form the type of a separate genus,” 2 but 
 until the entire Trilobite can be described it is better where 
 it is. 
 
 Loc. and Horizon. — Penkill, in greenish mudstone. (Gray 
 collection.) 
 
 1 Pal. Foss. Canada, i. pp. 323, 324, f. 308 and 309. 2 Op. jam tit., p. 171. 
 
CHEIR UR US. 
 
 107 
 
 Cheirurus, sp. ind. 
 
 (PI. VII., fig. 18.) 
 
 Obs. — We illustrate a specimen consisting of six thoracic 
 segments, which appears to be peculiar in the possession of a 
 very broad axis in proportion to the width of the pleurae. It 
 has very much the character of the form called C. octolobatus , 
 by M‘Coy and Salter, only it tapers from before backwards 
 much too rapidly for that species. So many disjecta membra 
 require piecing together, especially in the present genus, that 
 it becomes very difficult to determine a large number of frag- 
 ments such as that now under discussion. The width of the 
 axis cannot in itself be accepted as a distinctive character, 
 so many species of Cheirurus possess it. 
 
 Loc . and Horizon. — Drummuck Quarry. (Gray collection.) 
 
 Cheirurus (?) sp. ind. 
 
 (PI. VII., fig. 19.) 
 
 Obs. — Although minute and fragmentary, this specimen is 
 worthy of a figure on account of the well-marked glabella 
 furrows, also from the fact that the latter appear to be only 
 two in number, and almost pass completely across the glabella. 
 So far as preserved it is not unlike a species of Amphion (A. 
 pauper , Salter). 
 
 Loc. and Horizon. — Balcletchie, in dark-green mudstone. 
 (Gray collection.) 
 
 Genus Spiterexochus, Beyrich, 1845. 
 
 (Ueber einige bdhmische Trilobiten, p. 19.) 
 
 Sphserexochus mirus, Beyrich. 
 
 (PI. VII., fig. 20.) 
 
 S. mirus (Beyrich), Salter, Mon. Brit. Trilobites, 1864, pt. 1, p. 76, t. 7, f. 
 
 1-6 ( for synonomy). 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 68. 
 
 „ „ F. Roemer, Lethaea Geog., 1877, Atlas, t. 17, f. 9. 
 
 „ „ Woodward, Cat. Brit. Crust., 1877, p. 58. 
 
 Obs. — We only possess one specimen of this peculiar Trilo- 
 
io8 
 
 TR I LOB IT A. 
 
 bite, and so far as we recollect it has not hitherto been noticed 
 as a Girvan species. It is an imperfect glabella, showing the 
 strong basal glabella furrows and traces of the surface gran- 
 ulation. 
 
 Loc. and Horizon . — Dark-green coarse-grained ashes or ashy- 
 conglomerate of Balcletchie. (Gray collection.) 
 
 Genus Encrinurus, Emmrich, 1845. 
 
 (N. Jahrbuch fur Min., 1845, P* 4 2 -) 
 
 Encrinurus punctatus, Briinnich. 
 
 E. punctatus (Briinnich), Salter, Mem. Geol. Survey, Dec. vii., 1853, No. 4, 
 p. 6 {for general synonomy). 
 
 a. var. calcareus, Salter. 
 
 Encrinurus punctatus , Corda, Prodrom einer Monog. bohmischen Trilob., 
 1847, P- 9 D t. 5, f. 55. 
 
 Cybele punctatus , Fletcher, Quart. Jour. Geol. Soc., 1850, vi., p. 403, t. 32, f. 15. 
 
 Encrinurus punctatus, M‘Coy, Brit. Pal. Foss., 1851, fas. 1, p. 158. 
 
 E. punctatus , var. calcareus , Salter, Mem. Geol. Survey, Dec. vii., 1853, No. 4, 
 p. 6, t. 4, f. 15. 
 
 Asaphus tuberculatus , Buckland, Bridg. Treatise, n. ed.,;i858, ii., t. 64, f. 6. 
 
 E. punctatus, Salter and Woodward, Chart. Foss. Crustacea, 1865, p. 13, f. 
 
 . 52 ‘ 
 
 „ „ Baily, Char. Fossils, i., p. 67, t. 23, f. 2. 
 
 „ „ Salter, Murchison’s Siluria, 1867, 4th ed., p. 235, foss. 65, f. 5. 
 
 „ „ Salter, Cat. Camb. Sil. Foss., Woodwardian Museum, Camb., 
 
 1873* P- 77 - 
 
 „ „ Woodward, Cat. Foss. Crust., 1877, p. 37. 
 
 05 s . — Of Mr Salter’s variety calcareus we have examined 
 only two definite specimens from the Girvan district, both 
 pygidia, and not in a good state of preservation. They do 
 not call for further remark. We have given the synonomy 
 of E. punctatus under the two varieties established by Mr 
 Salter, and trust that this division will be found of service. 
 
 Hor. and Locality .■ — Penkill (Gray collection) ; burn passing 
 Bargany Pond, near Dailly {Coll. Geol. Survey, Scot., collected 
 by Mr A. Macconochie). 
 
ENCRINURUS. 
 
 109 
 
 b. var. arenaceus, Salter. 
 
 (PI. VIII., figs. 1-4.) 
 
 Calymene variotaris, Brongniart, Hist. Nat. Crust. Foss., 1822, t. 1, f. 3 A. 
 
 „ punctatus , Dalman, Vet. Acad. Handlinger, 1826, p. 233, t. 2, f. 2, 
 
 a and b. 
 
 ,, „ Murchison, Sil. Syst., 1839, t. 23, f. 8. 
 
 Encrinurus punctatus, Salter, Quart. Jour. Geol. Soc., 1851, vii., pp. 170 and 
 
 172, t. 9, f. 4. 
 
 Cybele punctata , Hall, Pal. N. York, 1852, ii., p. 297, t. A. 61, f. 1, g , 
 //, and i. 
 
 E. punctatus , var. arenaceus , Salter, Mem. Geol. Survey, Dec. vii., 1853, No. 
 
 4, p. 6. 
 
 „ „ Bronn, Lethaea Geognostica, 3d ed., 1851-56, i. p. 658, Atlas, 
 
 t. 9 2 , f. 24, a-c. 
 
 Asaphus tuberculatus , Buckland, Bdgw. Treatise, n. ed., 1858, ii., t. 64, f. 6. 
 
 E. Stokesii , M‘Coy, Sil. Foss., Ireland, 1864, p. 46, t. 4, f. 15. 
 
 Crypto?iemus punctatus, Angelin, Pal. Scandinavica, 1854, p. 3, t. 4, f. 4-8. 
 
 E. punctatus, Salter, Murchison’s Siluria, 1867, 4th ed., p. 90, foss. 15, f. 10. 
 
 „ „ var. arenaceus , Bigsby, Thesaurus Sil., 1868, p. 51. 
 
 „ „ „ Salter, Cat. Camb. Sil. Foss. Woodwardian Mus., 
 
 Cambg., 1873, p. 77. 
 
 E. punctatus , F. Roemer, Lethaea Geog., 1876, i., Th. Atlas, t. 17, f. 8, 
 a and b. 
 
 „ „ var. arenaceus, Woodward, Cat. Brit. Foss. Crustacea, 1877, 
 
 p. 36. 
 
 Obs . — The variety arenaceus , Salter, which has the termina- 
 tion of the pygidium deflexed and blunt, as distinguished from 
 the produced mucro of calcareus, appears to be the predom- 
 inating variety at Girvan. Nearly all the specimens are 
 mere casts, usually of the pygidium only, sometimes the latter 
 and a few of the thoracic segments united, and in one or two 
 instances small casts of the entire Trilobite. As a rule, the 
 pygidia, although casts, show traces of the characteristic tuber- 
 cules on the axis and ribs to a greater or lesser extent ; indeed 
 the features of the tail in E. punctatus are so well marked and 
 distinctive as to quite bear out Mr Salters remark, when describ- 
 ing E. vario laris — viz., that “the characters of the tail are amply 
 sufficient to separate the two common species.” 1 However, to 
 
 1 Mem. Geol. Survey, Dec. vii., No. 4, p. 7. 
 
no 
 
 TRTLOBITA. 
 
 afford assistance to those not having ready access to books, we 
 ofive the abbreviated characters of the tail in the three allied 
 species, which may be used as distinctive ones, taken from the 
 detailed descriptions of Messrs Fletcher 1 and Salter. 2 
 
 Encrinurus punctatus. — Axis of about thirty segments, with the centre smooth, 
 but having seven prominent and distinct tubercules, with an interval of four 
 rings between every two tubercules. Lateral ribs eight in number, separated by 
 deep furrows, and each with a tubercule at its proximal end. 
 
 E. variolaris. — Axis of ten rings, the first carrying a tubercule, the second a 
 punctum between two tubercules. The succeeding five rings have a tubercule, 
 and a punctum between two tubercules alternately; the three last have a 
 tubercule only. There are seven lateral ribs, each with a tubercule at its 
 proximal end. 
 
 E. sexcostatus. — Axis of twenty segments without tubercules. Lateral ribs six 
 in number, strong, flattened, with obtuse tips, divided by narrow deep furrows. 
 Surface of tail covered with a close scabrosity. 
 
 Loc. and Horizon. — Conglomerate of Cuddystone Glen 
 ( Salter ) ; sandstones of Saugh hill ( Salter ) ; Craighead lime- 
 stone ( Etheridge , 3 Mus. Pract. Geol. Collection) ; Penwhapple 
 (. Etheridge and Young ^ ibid.), all recorded simply as E . punc- 
 tatus. 
 
 The variety arenaceus occurs at Craighead, in the limestone 
 (Gray collection), and at Penkill in greenish mudstones (Gray 
 collection.) 
 
 Genus Cybele, Loven, 1845. 
 
 Cybele , Loven, Vet. Akad. Forhandlingar, 1845, No. 4, p. no. 
 
 Zethus (pars), M‘Coy, Brit. Pal. Foss., 1851, fos. 1, p. 156 (non Pander). 
 
 Cybele , Salter, Brit. Pal. Foss., 1851, App. A, p. iii. 
 
 „ Salter, Mem. Geol. Survey, 1864, iii., p. 324, note. 
 
 Obs . — We adopt the name Cybele as restricted by Salter, in 
 contradistinction to the interpretation of Volborth, M‘Coy, and 
 others, who considered it identical with Zethus , Pander. Mr 
 Salter states that Zethus was founded upon a fragment of a 
 Cheirurus , and is altogether a doubtful and dubious genus. 
 
 1 Quart. Jour. Geol. Soc., vi. pp. 403 and 405. 
 
 2 Dec. vii., No. 4, p. 3. 
 
 3 Mem. Geol. Survey Scot., Expl. 14, 1869, p. 9. 
 
 4 Ibid., Expl. 3, 1873, pp. 31 and 32. 
 
CYBELE. 
 
 1 1 1 
 
 Cybcle was placed by Salter as a sub-genus of Encrinurus , 
 from which it is chiefly distinguished by the possession of 
 twelve thoracic segments, usually produced into spines, the 
 position of the facial suture, and some minor points. 
 
 Cybele verrucosa, Dalman. 
 
 (Fig* 5 '•) 
 
 Calymcjie (?) verrucosa , Dalman, Vet. Akad. Handlingar, 1826, p. 285. 
 
 „ „ „ Om Palaeaderna, &c., 1827, p. 100. 
 
 „ „ „ Arsberattelse om nyare Zoologiska arbeten, 
 
 &c., 1828, p. 134, Note 1. 
 
 „ „ „ in Ferrussac’s Bull, des Sciences, Nat., 1829, 
 
 xix., p. 128. 
 
 Chaperon cCun Trilobite , Brongniart, Hist. Crust. Foss. 1822, p. 145, t. 4, 
 f. 11. 
 
 Trilobites ( Calymene ) verrucosa , Loven, Vet. Akad. Forhandlingar, 1845, 
 No. 3, p. 52, t. 1, f. 5, a-c. 
 
 Cybele verrucosa , Loven, loc. cit., No. 4, p. 111. 
 
 Atractopyge verrucosa , Corda, Prodrom einer Mon. bohmischen Trilob., 1847, 
 t. s. f - 5 2 - 
 
 Cybele sexcostata, Salter, Mem. Geol. Survey, 1848, ii., pt. i., t. 8, f. 9 (non 
 f. 10). 
 
 „ verrucosa , Salter, loc. tit., p. 343. 
 
 Zethus atractopyge, M‘Coy, Brit. Pal. Foss., 1851, fas. 1, p. 156, t. 1 G., f. 1-5. 
 
 Cybele verrucosa, Salter, Mem. Geol. Survey, 1853, die. vii., No. 4, p. 4. 
 
 „ „ Salter and Woodward, Chart Foss. Crustacea, p. 12, f. 48. 
 
 „ „ Morris, Cat. Brit. Foss., 1854, 2d ed., p. 103. 
 
 „ „ Salter, Mem. Geol. Survey, 1866, iii., p. 324, t. 19, f. 7. 
 
 „ „ Salter in Murchison’s Siluria, 1867, 4th ed., p. 206, Foss. 
 
 48, f. 2. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 47. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 33. 
 
 Obs . — We have seen several imperfectly-preserved examples 
 of this species from the Girvan district, sufficiently well marked 
 to make identification satisfactory. 
 
 Loc. and Horizon . — South side of Green-hill, Penwhapple 
 Glen {Coll. Mits. Pract. Geology ); Drummuck, in greenish-grey 
 mudstone ? (Gray collection) ; Balcletchie, in dark-green mud- 
 stone (Gray collection). C. verrucosa appears to have been first 
 collected in the Girvan neighbourhood by the late Mr Richard 
 Gibbs, and the specimen identified by Mr R. Etheridge. F.R.S., 
 and Dr J. Young, F.G.S. 
 
I I 2 
 
 TRILOB IT A. 
 
 Cybele rugosa, Portlock. 
 
 (PL VIII., figs. 5-7.) 
 
 Ogygia (?) n/gosa, Portlock, Geol. Report, Londonderry, 1843, P* 302, t. 5, 
 f. 10. 
 
 Cybele „ Salter in M'Coy’s Brit. Pal. Foss., 1851, fas. 1. App. A., 
 
 p. iii., t. i. G. f. 8. 
 
 „ ,, Bigsby, Thesaurus Sil., 1868, p. 47. 
 
 „ „ Morris, Cat. Brit. Foss., 2d ed., 1854, p. 103. 
 
 „ „ Salter, Cat. Camb. Sil. Foss., Woodwardian Mus., Cambg., 
 
 1873, P- 5 1 - 
 
 „ „ Woodward, Cat. Brit. Foss. Crust. 1877, p. 33. 
 
 Spec, char . — General form ovate-triangular, tapering rapidly 
 towards the posterior. Head or carapace nearly semicircular; 
 anterior margin strong, broad, vertical, and bent upwards in 
 front of the glabella. Free cheeks very convex, unsymmet- 
 rically hatchet-shaped, and produced posteriorly into short, 
 pointed, slightly curved, genal spines. Facial suture generally 
 sigmoidal ; posterior to the eye it curves outwards laterally 
 until near the thickened margin, when a sudden downward 
 curvature is taken, cutting the margin close to the genal spine ; 
 anterior to the eye the facial suture passes inwards towards the 
 glabella, and in front of the latter some little distance above the 
 front margin. Axal furrows broad and deep, well marked ; 
 marginal furrow distinct, but not deep ; neck furrow rather 
 broad and well defined, especially in the lateral portions. 
 Neck segment or lobe strong. Glabella elongate, slightly 
 clavate, attenuated posteriorly ; frontal lobe expanded and 
 overhanging the others, continuous with the main axis of the 
 glabella ; the three side lobes are club-shaped, connected with 
 the axis by narrow necks, and so united with one another as 
 to leave between them very shallow inconspicuous furrows and 
 deep oval pits between the narrow necks ; the upper or frontal 
 furrows are directed obliquely forwards, the middle and basal 
 are nearly at right angles to the glabella axis. The eyes are 
 situated nearer to the glabella than to the lateral margins, a 
 little behind the most convex part of the cheeks. Fixed cheeks 
 
CYBELE. 
 
 113 
 
 narrow and transversely elongated ; general surface, except the 
 anterior margin and genal spines, tuberculated. 
 
 Thoracic segments tapering rapidly towards the tail ; axis 
 about as broad as the pleurae, with a single line of tubercules on 
 each segment, and a few smaller ones scattered amongst them ; 
 pleurae sharply divided longitudinally by a groove, near the 
 anterior margin, into two very unequal parts, and produced 
 distally into flat angulated curved spines. Pygidium long, tri- 
 angular, gradually tapering to a point ; axis less in width than 
 the side lobes, of about twenty-eight coalesced rings, the divi- 
 sions being visible only on the sides, leaving a clear, smooth, 
 more or less longitudinal flattened space, unornamented and 
 without tubercules ; side lobes deflected, becoming strongly 
 bent down towards the apex of the tail ; the component pleurae 
 are five in number on each side, longitudinally curved when 
 viewed laterally, and increasing in size outwards from the axis, 
 each ornamented with a few tubercules ; between the three 
 upper ribs on each side an intermediate rugose small rib is 
 interpolated ; “ the lateral ribs have terminal spines, but the 
 four last ones are much longer ; they are united for some 
 distance, and then diverge to form the 4-5 serrate tip of 
 the tail.” 
 
 Obs . — With the exception of that of the tail, we are not 
 acquainted with any further description of Cybele rugosa ; it 
 was therefore very gratifying to find two or three examples 
 in Mrs Gray’s collection, from which we have been able to 
 draw up the above description, although some of the minor 
 details, such as the ornamentation of the pleurae and the full 
 extent of the spines, still remain to be further elucidated. 
 
 From Cybele bellatula , Dalman, the present species is dis- 
 tinguished, as it also is from C . verrucosa , Dalman, by possess- 
 ing much more decidedly hatchet-shaped free-cheeks, and by 
 their greater posterior extension. From the first it is also 
 distinguished by its highly ornate head, and from both by the 
 production of the posterior angles into spines. So far we 
 have no evidence of the two peculiar spines descending from 
 
 I-I 
 
TR 1 LOB IT. A. 
 
 H4 
 
 the sixth thoracic segment in C. rugosa , as in C. bellatula , 
 neither is there any trace of the ornate anterior margin of C. 
 verrucosa. The position of the eyes is also different in these 
 species to what it is in C . rugosa : in C. bellatula the eyes are 
 close to the glabella and far forward, judging from Angelin’s 
 figure ; 1 whilst in C. verrucosa they are situated almost half-way 
 between the glabella and the anterior lateral margin, and nearly 
 opposite the frontal furrow. On the other hand, in C. rugosa , 
 they are close to the lateral lobes of the glabella, and far back, 
 approaching the posterior margin, and almost opposite the 
 middle or ocular furrow. When we look at the tails of the 
 respective species we see a still further and more decided 
 difference. In the two Swedish species, which more or less 
 resemble one another, we notice, in the first place, that the 
 axis of the tail is more regularly segmented ; in the second 
 there is an absence of the deflection visible in C. rugosa ; 
 and, finally, the terminations of the lobes are free and not 
 coalesced to form a spine. 
 
 Cybele dentata , Esmark, 2 and C. brevicaudata, Angelin, 3 are 
 known only in the form of pygidia, and are easily distinguished 
 from C. rugosa by similar characters to the preceding species. 
 
 Loc. and Horizon . — In the greenish-grey mudstone of Drum- 
 muck ( Gray Coll.); Ladyburn, a little above Drummuck, in a 
 similar matrix ( Geol . Survey Scot. Coll. ) We believe that 
 Cybele rugosa was first indicated as a Girvan species by Mr 
 John Young, F.G.S. 4 
 
 Gejtus Dindymene, Corda, 1847. 
 
 Dindymene , Corda, Prodrom einer Mon. bohmischen Trilob., 1847, P- TI 9- 
 „ Barrande, Syst. Sil. Boheme, 1852, p. 816. 
 
 Obs . — The genus Dindymene was established by Dr Corda 
 for a very peculiar trilobite devoid of eyes and facial suture, 
 
 1 Pal. Scandinavica, t. 4, f. 1. 
 
 2 Angelin’s Pal. Scandinavica, t. 41, f. 12. 3 Ibid., t. 41, f. 14. 
 
 4 Proc. Nat. Hist. Soc. Glasgow, ii., pt. 2, p. 179. 
 
BIND YMENE . 
 
 "5 
 
 and in which the glabella is unprovided with furrows . 1 The 
 glabella is elevated somewhat above the cheeks, which are 
 convex and sub-triangular. The thorax has ten segments, and 
 its pleurae have their extremities produced into oblique, free 
 points or extremities, increasing in length posteriorly, and 
 there inclined to become parallel to the axis. The axis of the 
 pygidium is multi-segmentate. Upon each lateral lobe are two 
 pleurae, similar to those of the thorax, bent down nearly parallel 
 to the axis, and terminating in similar points produced a short 
 distance beyond its apex. We believe Dindymene has not 
 hitherto been recognised as a British form, and we were for 
 some time in much doubt to what genus to refer the fossils 
 which follow. The descriptions of Corda and Barrande, how- 
 ever, are so clear, especially when used in conjunction with 
 their admirable figures, that we think little doubt can be enter- 
 tained as to the correctness of our determination. 
 
 Dindymene Cordai, Etheridge, jun., and Nicholson, sp. nov. 
 
 (PI. VIII., fig. 8, and Fig. 5, A and B.) 
 
 Spec. char . — Outline of the head nearly semicircular ; front 
 margin somewhat bent up in the middle line, in front of the gla- 
 bella. The latter is strongly pyriform, and very convex, widest 
 at about, or a little less than, a third behind the anterior margin, 
 then rapidly narrowing to the neck furrow. No lobes or fur- 
 rows are present, and there is no point or occipital tubercule. 
 Cheeks convex, prominent, and obtusely triangular. Axal 
 furrows strong, deep, and wide ; neck furrow well marked but 
 not so strong as the axal furrows. Posterior angles produced 
 into diverging spines. Entire thorax unknown ; axis gradu- 
 ally tapering, moderately convex, the segments rounded, dis- 
 tinct, and prominent. The united portion of the pleurae a little 
 broader than the axis, the segments resembling those of the 
 latter, slightly bent downwards, terminating in short free points, 
 
 1 M. Barrande described a third species of this genus in the supplement to the 
 first volume of his Bohemian work, which has glabella furrows, — so that this state- 
 ment requires modification. 
 
TRILOBITA. 
 
 1 16 
 
 which become bent more and more parallel to the general axis 
 of the trilobite as the posterior end is approached. Pygidium 
 narrow; axis of many segments, about eight or ten (?), taper- 
 ing to a fine point ; the side lobes are very narrow and reduced, 
 being composed of two pleurae on each side, resembling those 
 of the thorax, and given off from the two first segments of the 
 axis ; the inner of these are pressed quite close to the lateral 
 margins of the axis, and both the inner and the outer terminate 
 in similar points to the pleurae of the thorax, the two inner by 
 their extension beyond the apex of the tail forming a well- 
 marked apical-notch. The surface of the glabella is ornamented 
 with granules or small tubercules, and that of the segments of 
 the body and tail is very minutely and inconspicuously granular. 
 
 Obs. — M. Barrande has described three species of this genus 
 from the Silurian rocks of Bohemia, all of which differ from the 
 present form. The markedly pyriform shape of the glabella 
 separates D. Cordai from all the Bohemian species, and the 
 
 Fig. 5. — A, Head-shield of Dindymene Cordai , Eth. and Nich., without eyes or facial suture, 
 but showing the granulated surface ; Ladyburn, above Drummuck, enlarged twice. {Coll. 
 Geol. Survey Scot.). B, Cast of pygidium accompanying the same, similarly enlarged. 
 (Compare fig. 8, PI. VIII.) C, Cast of pygidium of Cybele verrucosa , Dalm., similarly 
 enlarged, from Balcletchie. 
 
 absence of any trace of lobation from D. Bohemica, Barr, in 
 particular. In D. Friderici- A ugusti, Corda, and D. Haidin- 
 geri , Barr., the glabella swells out anteriorly, tapering gradually 
 towards the posterior, the axal grooves are somewhat curved, 
 and there is a cephalic tubercule present. In D. Cordai , nobis, 
 on the other hand, the axal grooves are straight, the glabella 
 is quite pyriform, becoming very narrow at the neck furrow, 
 and there is no trace of a cephalic tubercule. In the thorax of 
 D. Cordai the axis narrows, and the segments are individually 
 more rounded and projecting. 
 
STA UROCEPHAL US. 
 
 1 1 7 
 
 There is evidently a close resemblance between the tails in 
 all the species of this genus, but in D. Cordai , nobis, the axal 
 segments are more numerous than in D. Friderici- Augusti, 
 Corda, and the free terminations of the lateral lobes are more 
 widely separated. So far as we are aware, the biserial arrange- 
 ment of the tubercules on the axes of the thorax and pygidium 
 of the latter species does not exist in the Girvan form. 
 
 We were at first acquainted only with the tail of this species, 
 and had provisionally placed it in Cybele , Lov^n, but the acci- 
 dental discovery of a head and tail (Fig. 5, A and B) on the 
 same piece of matrix in the collection of the Geological Survey 
 of Scotland gave us a further clue. The general features of 
 this peculiar Tribolite are so marked, more especially those of 
 the head and tail, that little doubt can exist of the relation of 
 our fossil to those described by M. Barrande. 
 
 Loc . and Horizon. — Drummuck, in fine grey mudstone ( Gray 
 Coll. ) ; Ladyburn, above Drummuck, in a hard mudstone ; col- 
 lected by Mr A. Macconochie (Coll. Geol. Survey Scot.) 
 
 Genus Staurocephalus, Barrande, 1846. 
 
 (Note Preliminaire, p. 52; Syst. Sil. Boheme, 1852, i., p. 810.) 
 
 Staurocephalus globiceps, Portlock. 
 
 St. globiceps (Portlock), Salter, Mon. Brit. Trilobites, 1865, pt. 2. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 68. 
 
 „ ,, Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 59. 
 
 Obs. — In his ‘ Monograph,’ Mr Salter gave a woodcut 1 of a 
 specimen of this species from Ayrshire, without defining any 
 particular locality. We have been allowed to examine this 
 example, now in the Museum of Practical Geology, and find 
 that Salter’s figure does more than justice to the specimen, and 
 is greatly enlarged. The cheeks are much more convex than 
 in St. (?) unicus, and this with the position of the eye appears to 
 be a very good point of distinction between the two species. 
 
 Loc. and Horizon — Ardmillan Brae, in shale (Etheridge 2 ). 
 
 1 P. 86. 
 
 2 Mem. Geol. Survey Scot., Expl. No. 7, 1869, p. 10; Expl. No. 3, 1873, p. 32. 
 
TRILOB ITA. 
 
 1 18 
 
 Staurocephalus (?) unicus, Wyv. Thomson. 
 
 (PI. VIII., figs. 9-16, and Fig. 6, A, B.) 
 
 Acidaspis unicus , Wyv. Thomson, Quart. Jour. Geol. Soc., 1857, xiii., p. 209, 
 t. 6, f. 13 and 14. 
 
 St. (?) unicus , Salter, Mon. Brit. Tribolites, 1865, pt. 2, p. 86, t. 7, f. 22-24. 
 
 A/. Maclareni (Wyv. Thomson, MS.), Salter, loc. cit ., p. 86. 
 
 A/, unicus et AA Maclareni , Bigsby, Thesaurus Sil., 1868, p. 68. 
 
 ,, ,, Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 59. 
 
 Spec. char . — General form of the body oblong, and sparingly 
 ornamented with granules. Head broad, and rather long. 
 Free cheeks very minute, with entire margins. Eyes very 
 slightly, if at all, pedunculate, distinctly faceted, situated far 
 forward, immediately under the swollen hemispherical glabella 
 on each side. Neck furrow broad and strongly marked. Gla- 
 bella more or less clavate, with the frontal lobe produced into 
 a globular or somewhat more or less pyriform prominence, 
 occupying almost, if not quite, two-thirds of the whole length 
 of the entire glabella, much elevated above the general surface 
 of the head, and projecting above the frontal margin. The two 
 basal lobes bear no comparison to the frontal lobe, and are 
 separated from it by a broad, distinct, and well-marked furrow. 
 Cheeks broad, gently convex, and distinctly punctate, with a 
 thickened margin produced anteriorly into two almost straight 
 or slightly recurved spines, of variable length, but generally 
 short ; posterior angles produced into short recurved genal 
 spines. Thorax of twelve (?) segments ; axis convex, about 
 half as broad as the pleurae, or perhaps a little more ; pleurae 
 horizontal, with a double ridge running along each, the two 
 ridges coalescing at the distal extremity, and ending in a 
 strong, long, reflexed spine. Tail broad and short; axis of 
 two minute segments ; pleurae of the first tail segment spatu- 
 late, divided almost medianly by a shallow groove, and pos- 
 teriorly bent almost at right angles to the axis, and continued 
 backwards into two long spines. Ornamentation : thorax with 
 
ST A VROCEPHAL US. 
 
 1 1 9 
 
 a double row of minute granules on each segment ; pygidium 
 granular ; cheeks punctate ; frontal lobe of the glabella minutely 
 granular. 
 
 Obs. — This species was originally described by Sir Wyv. 
 Thomson as an Acidaspis , but it was transferred to Stauroce- 
 phaliis by Mr Salter in his earlier description of it. Prof. Wyv. 
 Thomson drew attention to the abnormal number of thoracic 
 segments present in St. unicus , and to its position as a link 
 between the Acidaspidcz and Cheiruridce. Salter remarked : 
 “If Prof. Thomson be correct in figuring twelve segments to 
 the body, the species is abnormal for either Acidaspis or Stau- 
 rocephalus. The shape of the head shows clearly enough that 
 it is to Staurocephalus, or else to one of the sections of Cheiru- 
 rus , that this bizarre fossil must be referred. Cheirurus often 
 has twelve segments, Acidaspis nine or ten, Staurocephalus 
 only ten. The grooved pleurae are unlike Staurocephalus , but 
 like the section Eccoptochile among the genus Cheirurus. But 
 no Cheirurus has so clavate a glabella, though a tendency 
 towards it is exhibited in some species, and Sphcerocoryphe of 
 Angelin is very near to our fossil.” If the almost entire cast 
 we figure (PI. VIII.) as St. unicus is in reality that species, 
 as we believe it to be, we think we are in a position to cor- 
 roborate Sir Wyv. Thomson’s view of the number of thoracic 
 segments, for we are strongly under the impression that this 
 cast possesses twelve. We are inclined to regard this as 
 St. unicus and not St. globiceps from the less convexity of the 
 cheeks, forward position of the eye, and spatulate appendages 
 to the tail. Salter, who was the first to figure the glabella of 
 St. unicus , represents the frontal lobe as much elongated or 
 pyriform, and projecting far beyond the frontal margin. Salter’s 
 figure must represent an extreme variety of St. tmicus, for not 
 one of the numerous heads of this species we have examined, 
 and which otherwise accord perfectly with the characters of 
 St. uniats , possesses this extremely pyriform and projecting 
 outline : on the contrary, they all more nearly resemble the 
 form of frontal lobe seen in the other species of the genus. 
 
I 20 
 
 TRILOB 1 TA. 
 
 The frontal lobes before us are hemispherical, or in one or two 
 cases very slightly pyriform, and without the anteriorly elon- 
 gated form of Salter's figure, 1 and quite accord with Barrandes 
 generic description. 2 The outline of the former more nearly 
 corresponds with Angelin’s Sphcerocoryphe , as displayed in the 
 type species S. dentata , than any of its fellows. We much 
 wish we possessed specimens of Sphcerocoryphe for comparison 
 with Staurocephalus , for we are quite convinced of the close* 
 relationship of the two genera. The position of the eyes in St. 
 
 unicus appears to be a little different from that in 
 either S. Murchison , Barr., S. globiceps , Portlock, 
 or clavifrons , Angelin. In St. unicus the eyes 
 
 are situated far forward, and as if sheltering them- 
 selves under the sides of the frontal lobe of the 
 glabella ; but in the three species just mentioned 
 the eyes have a more posterio-central position on 
 the lateral elements of the head. The bidentate 
 character of the limb is a well-marked and dis- 
 tinctive point in St. unicus ; but, strange to say, 
 the same peculiarity is present in Sphcerocoryphe 
 dentata, Angelin. 
 
 Sir Wyv. Thomson’s manuscript species S. 
 Maclareni was considered by Mr Salter identical 
 with St. unictts. We have been favoured with the loan of speci- 
 mens of the former from the Museum of Practical Geology, and 
 can fully bear out Salters statement. We give a figure of a 
 somewhat peculiar pygidium (Fig. 6, A), from another locality, 
 Shalloch Mill. It has the general character of that of St. unicus, 
 but the surface, including that of the long spines, is scabrous 
 (Fig. 6, B), instead of granular or tubercular. It may be spe- 
 cifically distinct, but the one specimen is all we have at present 
 at our command. It is in a calcareous shale. 
 
 Loc. and Horizon . — Penwhapple Glen, in schists at the base 
 of the Orthoceratite and Graptolite flags ( Wyv. Thomson ?) ; 
 
 A 
 
 Fig. 6.— A, Pygi- 
 dium of Stauro- 
 cephalus (?) uni- 
 cus, Wyville 
 Thomson ; pos- 
 sibly a variety 
 of it, or a new 
 species, of the 
 natural size. B, 
 Enlargement of 
 the surface of 
 the same. Shal- 
 loch Mill. 
 
 1 Monograph, t. 7, f. 22 b . 
 
 2 Syst. Sil. Bohm., i., p. 8 ii. 
 
A CIDASPIS. 
 
 I 2 I 
 
 Piedmont Glen 1 (as S. Maclareni , Wyv. T.); Balcletchie ( Gray 
 Coll.) ; Drummuck (Coll. Geol. Survey Scotland). 
 
 Staurocephalus nodulosus, Salter. 
 
 ,S. nodulosus , Salter (MS.), Mon. Brit. Foss., 1865, pt. 2, p. 87, t. 7, f. 25. 
 
 £ ind., Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 59. 
 
 Obs . — Under this name Salter figured two thoracic segments, 
 “an imperfect fossil, but distinct from St. unicus. It has tuber- 
 culate pleurae.” The pleural spines appear to be bent down at 
 a much more acute angle than in St. unicus. Nothing more 
 appears to be known about this fossil. 
 
 Loc. — Ayrshire. 
 
 The peculiar and interesting Trilobit Deipkon Forbesii, Bar- 
 rande, is stated 2 to have been found at Balcletchie, but we have 
 not met with any direct evidence of it. Hemispheric, disjointed 
 glabellae are common at that locality, but we see no reason to 
 doubt their identity with the preceding species but one. 
 
 Genus Acidaspis, Murchison, 1839. 
 
 Acidaspis , Murchison, Sil. Syst., 1839, P- 638. 
 
 „ Salter, Mem. Geol. Survey, Dec. vii., 1853, No. 6., p. 1. 
 Odontopleura , Emmrich, de Trilobitis, 1839, p. 33. 
 
 Acidaspis Lalage, Wyv. Thomson. 
 
 (PI. VIII., figs. 17-22.) 
 
 A. Lalage , Wyv. Thomson, Quart. Jour. Geol. Soc., 1857, XIII., p. 206, t. 6, 
 f. 1-5. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 33. 
 
 „ „ Woodward, Cat. Brit Foss. Crust., 1877, p. 19. 
 
 Spec. char. — General form oblong, inclined to square. Head 
 or carapace roundly triangular, moderately convex, with the 
 frontal margin rounded. Free cheeks small, fringed in front 
 
 Cat. Foss. Mus. Pract. Geol., 1865, p. 6. 
 
 2 Cat. W. Scot. Fossils, 1876, p. 16. 
 
I 22 
 
 TRILOBITA. 
 
 with short, minute spines ; posterior angles produced into short 
 divergent genal spines. Eyes somewhat remote ; ocular ridge 
 distinct. Facial suture apparently cutting the posterior margin 
 close to the base of the genal spines. Neck furrow strongly 
 marked. Glabella triangular, moderately convex, with a dis- 
 tinct, broad, median lobe, and two pairs of oval convex lateral 
 lobes entirely circumscribed, and of which the lower pair appear 
 to be a little the larger ; glabella furrows well marked and 
 deep. 
 
 Fixed cheeks very gibbous, separated from the glabella by 
 deep axal grooves. Neck segment convex and expanding 
 posteriorly, produced into two divergent or slightly curved 
 spines. Thorax square-oblong, horizontal, of nine or ten seg- 
 ments ; axis narrow and prominent ; pleurae convex, divided 
 by the pleural grooves into two ridges which coalesce at the 
 distal extremities, and are produced as long diverging poste- 
 riorly directed spines. “ Pygidium short, semicircular, of two 
 short segments fringed with from twelve to fourteen long 
 radiating equal spines ; a ridge from the anterior axis-segment 
 is continuous with the antepenultimate spine on either side.” 
 General surface tuberculate, the head more so than the body ; 
 tail reticulate. 
 
 Obs . — Our description is drawn up from several detached 
 fragments of this species, as we have not seen a complete 
 example ; the characters of the tail are taken from Prof. 
 Thomsons description. We are able to add one or two 
 characters to the original general diagnosis of the Trilobite, 
 which will serve to fix the species in a more satisfactory 
 manner. The occurrence of the cheeks appears to be rare, for 
 only in one example in the Gray collection is there any trace 
 of them ; indeed, information about the free cheeks and eyes 
 is required before the above remarks relating to them can be 
 considered as definite. The circumscribed lateral lobes of the 
 glabella appear to be well-marked features of A. Lalage , so 
 also do the gibbous fixed cheeks with their closely set tuber- 
 cules. Another point to be noticed in the structure of this 
 
ACIDASPIS. 
 
 123 
 
 species is the highly tuberculate head, as compared with the 
 sparingly ornamented body and reticulate tail. 
 
 A. Lalage may be distinguished from its ally A. hystrix , 
 Wyv. Thomson, by the more uniform character of the lat- 
 eral lobes of the glabella, by its single, as compared with the 
 double thoracic pleural spines of the latter, and by possessing 
 a reticulate instead of a tuberculate surface to the pygidium. 
 From A. Graycz , R. Etheridge, which it resembles in the 
 reticulate tail, A . Lalage may be distinguished by the simple 
 nature of its spines, by the smaller and less developed con- 
 dition of the spines of the last thoracic segment, and by a 
 dissimilar number of spines fringing the pygidium. 
 
 Sir Wyv. Thomson says , 1 “ The form of the tail of this species 
 at once distinguishes it from all its British congeners, as indeed 
 from all species hitherto described, with the exception of A. 
 radiata , which it closely resembles. The tail-spines of the 
 present species are longer than in A. radiata , and slightly 
 curved.” We may observe on this point that, according to 
 Goldfuss’s figure , 2 the posterior axis segment of the tail is 
 represented by two nodes or elevations, which quite separates 
 it from A. Lalage . 
 
 Loc . and Horizon . — Penwhapple Glen, in schists at base 
 of the Graptolite and Orthoceratite flags {Wyv. Thomson). 
 Balcletchie {Gray Colli) 
 
 Acidaspis hystrix, Wyv. Thomson. 
 
 (PI. VIII., figs. 23-25.) 
 
 A. hystrix , Wyv. Thomson, Quart. Jour. Geol. Soc., 1857, xiii., p. 207, t. 6, 
 f. 6-10. 
 
 „ „ Bigsby, Thesaurus Sil., 1 868, p. 33. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, P- T 9- 
 
 Spec. char. — General form parallelogrammatic, slightly taper- 
 ing posteriorly, densely fringed with spines. Head or carapace 
 almost semicircular. Limb of the free cheek ornamented with 
 a fringe of short simple spines, increasing in length backwards ; 
 
 1 Quart. Jour. Geol. Soc., xiii., p. 207. 
 
 2 N. Jahrbuch, 1843, t. 4, f. 1. 
 
124 
 
 TRILOBITA. 
 
 posterior angles produced into curved genal spines extend- 
 ing backwards to the third thoracic segment, and so curved 
 that the convexity is outward laterally from the body of the 
 trilobite, when in its natural position. “ Glabella broadly tri- 
 angular, not very highly arched ; middle lobe rather narrow ; 
 lateral lobes two, oval, separated by distinct grooves from the 
 central lobe and from the cheek basal lateral lobe fused with 
 the neck segment. Portion of the cheek within the facial 
 suture very gibbous, likewise confluent with the neck segment. 
 Neck segment very prominent, separated from the middle lobe 
 of the glabella by a shallow groove.” Thorax of nine seg- 
 ments ; axis narrow and prominent, rounded ; pleurae horizon- 
 tal and convex, divided into an anterior and posterior portion 
 by a groove which is placed somewhat nearer the anterior than 
 the posterior margin of each pleura, so that the latter are 
 divided longitudinally into two unequal portions ; the anterior 
 half terminates in a short pointed reflexed spine, the posterior 
 on the other hand terminating in a long, simple, more acutely 
 reflexed straight spine, very gradually tapering ; the spines 
 are so placed, with regard to one another, that the short 
 anterior spine of one pleura passes under the posterior 
 spine of the pleura next in front, the length of the former 
 being such that in nearly every case two are overlaid by the 
 same posterior long spine. Pygidium minute, short, and a 
 little less than the width of the thorax ; axis of two seg- 
 ments, the anterior giving off ridges on each side continuous 
 with the antepenultimate spine of the tail on each side ; limb 
 produced into twelve nearly parallel or slightly radiating 
 spines, graduating in length right and left from the two 
 central ones, which are nearly equal. The spines of the last 
 thoracic segment are more acutely bent down than any of the 
 others of the thorax, and are extended backwards beyond the 
 extremity of the longest tail - spines. Surface of the head, 
 thorax, and pygidium densely granular, the granules on the 
 thorax being arranged in two lines on each of the divisions 
 of the pleurae. 
 
A CIDASPIS. 
 
 2 5 
 
 Obs. — The regular contour, long radiating spines, and highly 
 granular surface give to this species a peculiarly graceful ap- 
 pearance. According to Sir Wyv. Thomson, A. hystrix some- 
 what resembles A. Prevosti , Barr ., 1 but the structure of the 
 head, and the number and arrangement of the tail-spines (six- 
 teen), distinguish it. The elongated large basal lateral lobes of 
 the glabella will serve to distinguish the head of the present 
 species from that of A. Lalage ; whilst as regards the thorax, 
 the profuse granulation and spines of two orders in A. hystrix 
 will be sufficient. In the one the tail is reticulate, in the other 
 tuberculate. The doubly-spined pleurae and granular orna- 
 mentation separate A. hystrix from A. Graycz , R. Eth., to 
 say nothing of the denticulated spines of the latter form, but 
 unfortunately we are unable to compare the heads of the two 
 species. Acidaspis Dufrenoyi , Barr ., 2 resembles A. hystrix to 
 a certain extent, but the distal ends of the pleurae are produced 
 into three spines each, one of them almost vertical, and the 
 others sub-parallel, not passing under one another. Again, the 
 thorax is ornamented with only one row of tubercules on the 
 pleurae, arranged vertically, and two on the axis, and the pygi- 
 dium is plain except on the axis. In the double spines to the 
 pleurae, A. hystrix resembles A. ovatus , Emmrich , 3 but the 
 arrangement is different. 
 
 Acidaspis callipareos, Wyv. Thomson. 
 
 A. callipareos , Wyv. Thomson, Quart. Jour. Geol. Soc., 1857, xiii., p. 208, 
 t. 6, f. 11, 12. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 33. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 18. 
 
 Obs. — Although we have not had the advantage of studying 
 the original specimens upon which Sir Wyv. Thomson based 
 his determinations, we are inclined to think that the head de- 
 scribed in his interesting paper under the above name would 
 have been more appropriately ascribed to the thorax and pygi- 
 
 1 Syst. Sil. Bohm., i., p. 739, t. 39, f. 33-41. 2 Ibid., i. t. 38, f. 25. 
 
 3 Odontopleura, Emmrich, Untersuch. iiber boh. trilob., 1846, p. 18, t. 3, f. 1. 
 
126 
 
 TR I LOB IT A. 
 
 dium 1 named by him A. hystrix — a view which is borne out 
 by the highly ornate character of the test in the whole of the 
 remains referred to. In the only specimen of A . hystrix in the 
 Gray collection in which the head is shown it is unfortunately 
 imperfect, and, so far as preserved, the distinctive characters 
 assigned to it by Sir Wyv. Thomson cannot be satisfactorily 
 made out, as they appear to be common throughout the genus. 
 Of A. hystrix , Prof. Thomson remarked, “We have only one 
 specimen of this species showing the head,” whilst of A. calli- 
 pareos only the head is known likewise. According to the 
 descriptions of the two species, the heads chiefly differ in that 
 of A . hystrix having the basal lateral lobes fused with the 
 neck segment, and the fixed cheeks confluent with the neck 
 segment. It is just possible that the imperfect state of the 
 head of A. hystrix may have given rise to the appearance of 
 characters which did not really exist ; they are, however, said 
 to be from different horizons. 
 
 Loc . and Horizon. — Sandstone of Mulloch Hill. (Coll., Wyv. 
 Thomson.) 
 
 Acidaspis Grayse, R. Etheridge, jun. 
 
 (PI. VIII., fig. 26 : PI. IX., figs. 1-6, and 7 (?) ; Fig. 7 B.) 
 
 A. Grayce , Eth., jun., Proc. R. Physical Soc., Edinb., 1878, iv., pt. 3, p. 170, 
 t. 2, f. 6-8. 
 
 Spec. char. — General form oblong-oval, depressed, bordered 
 with a fringe of delicate, radiating spines. Head rounded, 
 triangular convex ; limb of the free cheek produced into a fringe 
 of delicate, simple spines graduating and becoming longer from 
 before backwards. Glabella apparently oval, convex, basal 
 lobes oval, elongated, apparently quite circumscribed. Poste- 
 rior angles produced into genal spines which extend backwards 
 for about half the length of the thorax, and appear to be but 
 little bent or curved ; neck segment prominent and apparently 
 non-spinous ; surface of the glabella and lobes covered with 
 scattered tubercules or granules. Thorax horizontal, square- 
 
 1 Loc. c it .y t. 6, f. 7 and 8. 
 
A CIDASPIS. 
 
 127 
 
 oblong, of ten segments ; axis narrow and prominent, gradually 
 decreasing in width towards the pygidium ; pleurae horizontal, 
 traversed by a nearly central groove, and produced laterally 
 into long, recurved, denticulated spines, those of the last seg- 
 ment (that next the pygidium) bent down almost in a parallel 
 direction with the limb-spines of that division of the body — no 
 trace of surface - ornamentation preserved. Pygidium short, 
 semicircular, surface reticulate ; axis of two segments ; limb 
 produced into fifteen sub-equal radiating denticulated spines ; 
 the anterior axis segment gives off a ridge on each side, con- 
 tinuous with the antepenultimate spines on each side the cen- 
 tral one of the pygidium ; the denticles are sub-alternate on 
 each side of contiguous spines, and alternate on opposite sides 
 of the same spine. 
 
 Obs . — All the specimens of this species contained in Mrs 
 Gray’s cabinet are more or less fragmentary, with the excep- 
 tion of that represented by Fig. 6, a cast; and even here the 
 specimen is a good deal crushed, and the characters of the 
 carapace obliterated. So far as present observation has 
 enabled us to judge, the spines projecting from the anterior 
 part of the carapace are simple, whilst those of the thorax 
 and pygidium are unquestionably denticulated. The head is 
 not in a good state of preservation, and little can be said about 
 the characters of the glabella, its lobes and furrows, the facial 
 suture, and the fixed and movable cheeks, except that the 
 glabella and lobes appear to have been convex and prominent. 
 
 Amongst British species, A. Grayce must be first compared 
 with three species of Acidaspis from Girvan, described by Sir 
 Wyville Thomson, F.R.S. 1 The form and general propor- 
 tions of the thorax and pygidium closely resemble those of two 
 of these — A. Lalage and A. hystrix ; but the characters of the 
 carapace, so far as they can be made out, do not correspond 
 particularly, in the absence of any cervical spines in A. Grayce . 
 It undoubtedly differs from A. Lalage in its denticulated spines, 
 those of the latter being quite simple and plain, both on the 
 Quart. Jour. Geol. Soc., 1857, xiii., pp. 206-209. 
 
 1 
 
TRILOB IT A. 
 
 128 
 
 pygidiimi and thorax. Similarly it is also distinguished from 
 A. hystrix , Wyv. Thomson, and A. Caractaci , Salter; in the 
 first of these each pleura terminates in two reflected spines, 
 one passing under the other, and in the latter is bispinose, one 
 spine being much longer than the other, but in neither case are 
 the spines denticulated. Again, A. Graycz does not appear 
 to agree with any other described British species with which 
 we are acquainted, either by specimens or figures, such as 
 A. Barrandei , Fletcher; A. bispinosct, M‘Coy; A. Brightii , 
 Murchison; A. coronatus , Salter; A. Jctmesii , Salter; or 
 A. Hughesii , Salter. In fact, the increased number of spines 
 
 round the pygidium separates A. Graycz from all the foregoing 
 forms, to say nothing of their denticulated character, except A . 
 Lalage and A. hystrix , where the spines are twelve to fourteen 
 in the one case, and twelve in the other, and apparently all 
 simple. All the specimens of pygidia which we refer to A. 
 Graycz have constantly fifteen denticulated spines, except in 
 one specimen where we counted, sixteen. 
 
 Leaving British species and passing ,to Bohemian Silurian 
 Trilobites, we find there are several with which a comparison 
 may be made. M. Barrande has figured two species with the 
 spines of the pleurae denticulated — Acidaspis Keyserlingi, Barr ., 1 
 and A. mira , Barr . 2 In the first of these the spines in question 
 are of a form totally different from those of A. Graycz , and the 
 thoracic axis is very much broader in proportion to the general 
 size of the trilobite. In A. mira the spines of the pleurae are 
 of two kinds, one denticulated and the other not, both attached 
 to the same pleura. In neither are the spines of the pygidium 
 denticulated, but M. Barrande also figures at least five species 
 in which these particular spines are so, viz. : — 
 
 1. A. Verneuilii, Barr., loc. cit., t. 38, f. 1-9. 
 
 2. A. Portlockii, „ ,, „ f. 10-12. 
 
 3. A. vesiculosa, ,, „ „ f. 13-21. 
 
 4. A. tricornis, „ „ suppl., t. 8, f. 21. 
 
 5. A. rara, „ „ „ t. 12, f. 28. 
 
 Syst^me Sil. Boh., I., t. 36, f. 10-22. 
 
 2 Ibid., t. 39, f. 1 - 1 1 . 
 
ACID ASP IS. 
 
 129 
 
 In the first three of these the form of the pygidium, and the 
 number, form, and arrangement of the spines into which the 
 limb of each is produced, are so different as to necessitate little 
 or no comparison. The ornamentation of these trilobites con- 
 sists of small granules or tubercules, both on the thorax and 
 pygidium ; on the other hand, on the only part of A. Graycz 
 where the ornamentation is preserved, it is seen to be reticulate, 
 as in A. Lalage. In A. tricornis , Barr., the pygidium spines 
 are only eight in number; finally, there are eight also in A. 
 mira , but the arrangement of them is again different from any 
 of the preceding. 
 
 A specimen of this species lately obtained by Mrs Gray 
 leads us to think that the ar- 
 
 rangement of the spines was 
 even more complicated than 
 at first supposed. It will be 
 seen that in Fig. 7, A and B, 
 two pleurae taken from a larger 
 specimen, the central portion 
 of each pleura terminates in 
 the long denticulated spine as 
 described, and there appears 
 to be anterior and posterior to 
 this the broken bases of other 
 
 Fig. 7. — A, Part of one side of thorax of Acid- 
 aspis, sp. , with long and slender spines, of 
 the natural size, from Balcletchie. B, Part 
 of one side of thorax of Acidaspis Graycc, 
 Eth., jun., enlarged twice, with one pleura 
 enlarged still further. At the termination 
 of the pleurae is seen the central denticulated 
 spine, along with the broken bases of the 
 anterior and posterior spines of the same 
 (from Balcletchie). C, Pygidium of Acid- 
 aspis, sp. ind., with six spines, enlarged 
 twice (cast from Mulloch Hill). 
 
 supplementary spines : whether these were also denticulated 
 we cannot say. 
 
 Loc. and Horizon. — Balcletchie, in a fine, greenish mudstone 
 ( Gray Colli) 
 
 Acidaspis, sp. ind. 
 
 (Fig. 7 C.) 
 
 (Compare Acidaspis ( Ceraurus ) crenatus , Emmrich, as figured by Loven, 
 Ofv. K. Vet. Aka'd. Forhandl., 1845, No. 3, p. 47, t. 1, f. 1, a-f.) 
 
 Obs K — The pygidium we represent in Fig. 7 C is quite different 
 from any others which have come under our notice. The axal 
 segments are not distinctly preserved, but they are apparently 
 
 1 
 
TRILOBITA. 
 
 130 
 
 two in number. As usual in this genus, from the anterior of 
 the two proceed two ridges, which on reaching the margin are 
 prolonged into straight, tapering, plain spines. Between these 
 are two smaller and shorter ones, placed opposite the termina- 
 tion of the axis. External to the two principal spines are two 
 small prolongations, almost proceeding from the angles of the 
 pygidium, and the shortest of all those visible in the specimen. 
 No traces of ornamentation are preserved. 
 
 This form of pygidium differs from all the other Girvan 
 species here described, by the fact that the elongated spines, 
 continuous with the ridges from the first axal segment, are 
 separated by only two secondary spines proceeding from the 
 limb of the pygidium, instead of three or more, as in A. Lalage , 
 A. hystrix , or A . Graycz, as the case may be ; and that external 
 to these primary spines, the secondary are reduced to one on 
 each side. M. Barrande has figured several Bohemian forms 
 
 o 
 
 in which a similar number and arrangement of spines is to be 
 seen, as in the species under consideration, but in each case 
 there is also present some other good distinctive character. Such 
 are A. Dormitzeri , Barr. ; 1 A. Laportii , Barr. ; 2 A. propinqua , 
 Barr .; 1 * 3 A. Roemeri, Barr. ; 4 A. Geinitziana ; 5 and A. direlicta, 
 Barr . 6 Much nearer, however, than any of the foregoing is A. 
 (Cer aunts) crenatus , Emmrich, as figured by Loven. Here we 
 find an exact representation of the spines seen in the Girvan 
 fossil, except that in Loven’s figure the whole of the parts are 
 on a much larger scale. We think it not at all improbable that 
 it may be a small variety of A. crenatus , or else an undescribed 
 form, 
 
 Loc. and Horizon . — Mulloch Hill ( Gray Coll) 
 
 Acidaspis (?) sp. ind . 
 
 (Fig. 7 A.) 
 
 Obs . — We figure this fragment of a thorax from the fact that 
 it appears to differ in the length of its spines and other minor 
 
 1 Syst. Sil. Boh. Atlas, I., t. 38, f. 22. 
 
 3 Loc. cit., t. 39, f. 25. 
 
 5 Loc. cit., t. 39, f. 49. 
 
 Loc. cit., t. 39, f. 23. 
 4 Loc. cit., t. 39, f. 29. 
 Loc. cit., Suppl. I., t. 7, f. 10, t. 9, f. 4. 
 
LICHAS. 
 
 I 3 I 
 
 characters from any of the other Girvan forms which have come 
 under our notice. We provisionally refer it to Acidaspis , 
 although we quite admit that it may be a Staurocephalus, but 
 probably the former. The central ridge of each pleura is 
 minutely granulated, and is produced into a long, tapering, 
 posteriorly-recurved, simple spine. The horizontal portions 
 of the pleuree appear to be unornamented. 
 
 Loc. and Horizon . — Balcletchie, in a fine-grained greenish 
 mudstone ( Gray Coll . ) 
 
 Genus Lichas, Dalman, 1826. 
 
 (Ofv. Vet. Akad. Handlingar for aar 1826, p. 93.) 
 
 Lichas laxatus, M‘Coy. 
 
 Lichas laxatus (M‘Coy), Salter, Mem. Geol. Survey, 1848, II., pt. 1, p. 340, 
 t. 8, f. 4-6. 
 
 ,, „ Salter, Quart. Jour. Geol. Soc., 1851, VII., p. 172, t. 9, f. 5. 
 
 „ „ Morris, Cat. Brit. Foss., 1854, 2d ed., p. no. 
 
 „ „ M‘Coy, Sil. Foss. Ireland, 1862, p. 51, t. 4, f. 9. 
 
 ,, „ Salter, Mem. Geol. Survey., 1866, III., p. 324, t. 19, f. 1-3. 
 
 „ ,, Salter, in Murchison’s Siluria, 1867, 4th ed., p. 204, foss. 
 
 46, f. 5. 
 
 „ „ Bigsby, Thesaurus, Sil., 1868, p. 57. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 43. 
 
 Obs . — We know this as a Girvan species only from the 
 figure given by Mr Salter, representing a small glabella, show- 
 ing very distinctly the narrow neck of the latter, and the cir- 
 cumscribed side-lobes, although it appears to us that these are 
 represented in this figure as much more oval in outline than 
 those of the later figures of the same author. 
 
 Loc . and Horizon. — Lower Thrave, in yellowish sandstone 
 (Salter), on a similar horizon to the beds of Mulloch Hill 
 quarry. 
 
TRILOB ITA. 
 
 1 32 
 
 Lichas Barrandei, Fletcher (?). 
 
 (PI. IX., fig. 8.) 
 
 L. Barrandei , Fletcher, Quart. Jour. Geol. Soc. 1850, vi., p. 238, t. 27, 
 f. 10, t. 27 bis, f. 5. 
 
 ,, ,, Morris, Cat. Brit. Foss., 1854, 2d ed., p. no. 
 
 „ ,, Salter in Murchison’s Siluria, 1867, 4th ed., p. 234, foss. 64, 
 
 f. 3 . 
 
 ,, „ Bigsby, Thesaurus SiL, 1868, p. 57. 
 
 „ „ Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 43, 
 
 Obs. — We are indebted to Mr R. Etheridge, F.R.S., for the 
 loan of a pygidium of this species from the M.P.G. Collection, 
 but as we are unable to add to Mr Fletchers description, we 
 content ourselves with simply giving a figure of the specimen. 
 We have to observe, however, that, unlike Fletcher’s example, 
 the axis of ours is not wider than the side-lobes, scarcely so 
 wide indeed. It will be seen by the figure that the projecting 
 teeth of the broad foliaceous pleurae are not visible, consequent 
 upon the non-preservation of the margin. In this state some 
 hesitation might be manifested whether to refer the specimen 
 to L. Barrandei, FL, or L. laciniatus, Dalman, and indeed it 
 appears really to occupy an intermediate position between the 
 two. In some respects the specimen approaches L. Barra7idei, 
 and in others equally so L. laciniatus. Unfortunately the 
 matter is not simplified by the indefinite character of the 
 margin of the Girvan specimen. However, it appears to 
 possess the three - segmented axis, broad foliaceous pleurae 
 with their central division, the axal tubercle, and the rapidly 
 attenuated posterior portion of the axis of both species, but 
 the axis and the attenuation . are relatively much narrower 
 than in either of the above, but of the two it is probably 
 nearer L. Barrandei than L. laciniatus. On the other hand, 
 the outline of the margin, so far as it is preserved, assumes 
 more the form of L. laciniatus, especially of Loven’s figure, 1 
 although there are at the extreme apex, we think, indications 
 
 Ofv. Vet. Akacl. Forhandl., 1845, No. 3, t. 1, f. 7, a and b. 
 
UCHAS . 
 
 I 33 
 
 of a notch, which would be a strong indication of alliance with 
 L. Barrandci. This is only one of the many unsatisfactory 
 points which have appeared during the examination of the 
 present collection, and which can only be settled by the 
 acquisition of further material. It is the L. laxatus of the 
 Catalogue of Fossils in the Museum of Practical Geology , 1 
 quoted from Girvan, but not of M‘Coy. 
 
 Loc. and Horizon . — Mulloch Hill (Coll. Mus. Pract. Geol.) 
 
 Lichas Hibernicus, Portlock. 
 
 (PI. IX., figs. 9, 10.) 
 
 Nuttania Hibernica , Portlock, Geol. Report, Londonderry, 1843, p. 274, t. 1, 
 f. 1, t. 5, f. 1-3. 
 
 „ ,, Morris, Cat. Brit. Foss., 1843, p. 75. 
 
 Lichas „ Beyrich, Ueber einige Bohm. Trilob., 1845, PP- 2 5 > 2 9 - 
 
 „ „ Bronn, Index Pal. Nomenclator, 1848, p. 641. 
 
 „ „ M‘Coy, Sil. Foss. Ireland, 1862, p. 51. 
 
 ,, „ Bigsby, Thesaurus Sil., 1868, p. 57. 
 
 ,, sp. R. Etheridge, jun., Proc. R. Phys. Soc., 1878, iv. pt. 3, 
 
 p. 169. 
 
 Spec. char. — Head obtusely semicircular or semi-oval, and gib- 
 bous in front. Glabella convex, broader in front than behind ; 
 forehead lobe continuous from the front margin backwards to 
 the neck-segment, and not expanding posteriorly ; anterior por- 
 tion of the forehead-lobe expanding, and slightly overhanging 
 the side-lobes ; neck of the glabella rather broad, flattened, 
 formed by its posterior prolongation to the neck segment. 
 Side-lobes elongate, concavo-convex laterally, extending rather 
 further back than the base of the glabella. Neck segment 
 broad but not very convex. Surface covered with pustules of 
 various sizes and irregular form, arranged without regard to 
 order. Glabella furrows well marked. 
 
 Obs. — We are only acquainted with the glabella of this 
 species from Girvan, but its characters are so essentially simple 
 as compared with most other members of the genus, that it 
 is easily recognised. The almost straight neck-lobe, with the 
 
 1 1865, p. 21. 
 
*34 
 
 TRILOB I TA. 
 
 oval side-lobes descending quite to the latter, without the 
 intervention of any intermediate lobes, is very characteristic. 
 It is the Lichas avus of the ‘ Catalogue of Western Scottish 
 Fossils/ but not of M. Barrande. It certainly resembles the 
 Bohemian form in the character of its ornamentation ; otherwise 
 it is totally different. 
 
 We have four specimens, all glabellae, and only in one speci- 
 men are the accessory lobes preserved ; the others consist 
 merely of the forehead and side lobes. L. macrocephala , 
 Eichwald, is another similar form. 
 
 Lichas ornatus, Angelin, closely resembles the Girvan 
 species, and like it has the large side-lobes descending to the 
 neck-furrow, giving it a bold and marked appearance. 
 
 Loc. and Horizon. — Craighead quarry, in limestone ; Bal- 
 cletchie, in fine-grained mudstone. (Gray collection.) 
 
 Lichas Grayii, Fletcher (?). 
 
 (PI. IX., figs. II, 12.) 
 
 Lichas Grayii , Fletcher, Quart. Jour. Geol. Soc., 1850, vi., p. 237, t. 27, f. 8, 
 t. 27 bis, f. 3, a and b. 
 
 „ „ Morris, Cat. Brit. Foss. 2d. ed. 1854, p. no. 
 
 „ „ Bigsby, Thesaurus Sil., 1868, p. 57. 
 
 ,, ,, Woodward, Cat. Brit. Foss. Crustacea, 1877, p. 43. 
 
 Spec. char. — Head nearly semicircular, gibbous in front. 
 Glabella large, convex, as broad or broader anteriorly than 
 posteriorly ; forehead-lobe continuous from the front margin 
 to the neck-segment, narrowing posteriorly till on a level with 
 the base of the side-lobes, where it is marked by a slight con- 
 striction or transverse groove, then suddenly expanding at the 
 base, with a slight prominence or node on each side. Upper 
 lateral lobes oval, obtusely pointed, not extending to the neck- 
 segment, but cut off by the posterior expansion of the forehead- 
 lobe ; lateral side-lobe more or less triangular. Neck-segment 
 not prominent ; glabella furrows well marked ; surface covered 
 with close-set granules. 
 
 Obs. — We refer this specimen to L . Grayii provisionally, as 
 
LICHAS. 
 
 *35 
 
 we have not had the advantage of comparing it with any 
 typical examples : it appears to agree better with this species, 
 however, than with any other. The form of the side-lobes 
 and the posterior expansion of the forehead-lobe separate our 
 specimen from Lichas Bucklandi , M. Edw., and L. Salteri, 
 Fletcher. From L. laxatus , M‘Coy, and L. verrucosus , Eich- 
 wald, it is separated by the much greater width of the neck 
 of the forehead-lobe, and the different form of the supplemen- 
 tary side-lobes. Its dissimilarity to L. Hibernicus is at once 
 apparent. 
 
 Loc . and Horizon. — Drummuck, in fine-grained greenish 
 mudstone. (Gray collection.) 
 
 Lichas, sp. ind. 
 
 (PI. IX., figs. 13, 14.) 
 
 Obs. — This is in all probability a portion of the cephalic 
 shield of a Lichas. We observe the fore part of the forehead- 
 lobe, and a small portion of the right side-lobe, a portion of the 
 eye-lobe, and the right eye with its facets, preserved. The 
 lobes are all granulated. On the under side is visible the 
 hypostome, of an oval or egg-shaped form, with one of its alar 
 prolongations partially preserved. This fragment is interesting, 
 from the forward position of the eye in relation to its position 
 with the side-lobe, and its size. 
 
 Loc. and Horizon. — Drummuck. (Gray collection.) 
 
 END OF TIIE FIRST FASCICULUS. 
 
 PRINTED BY WILLIAM BLACKWOOD AND SONS. 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ' 
 
 ' 
 
 . 
 
 ■ 
 
 
 
PLATE I. 
 
 Fig. r. Small specimen of Lyopora favosa , M‘Coy, sp., of the natural size. 
 Coll. H. A. Nicholson. 
 
 Fig. i a. A few calices of the same, enlarged. 
 
 Fig. i b. Thin transverse section of the same, viewed on a dark background, 
 of the natural size. Coll. H. A. Nicholson. 
 
 Fig. i c. Another transverse section, also viewed on a dark background, of the 
 natural size. Coll. H. A. Nicholson. 
 
 Fig. i d. Vertical section of same, similarly viewed, of the natural size. Coll. 
 H. A. Nicholson. 
 
 Fig. i e. A few calices of i c , enlarged about ten times. 
 
 Fig. 2. Side view of a large specimen of Favosites Girvanensis , Nich., and Eth. 
 jun., of the natural size. 
 
 Fig. 2 a. Under surface of an average example of the same, of the natural size. 
 
 Fig. 2 b. Vertical section of the same, showing tabulae, enlarged about twenty- 
 five times. 
 
 Fig. 2 c. Vertical section of another example, without tabulae, similarly en- 
 larged. 
 
 Fig. 2 d. Transverse section of the same, similarly enlarged. 
 
 Fig. 3. Transverse section of Tetradium Peachii , magnified about one hun- 
 dred times. Coll. H. A. Nicholson. 
 
H.Alleyne Nicholson 
 
 Plate I. 
 
 C.Berjeau, lith. 
 
 C.'Waterston, Sons & Stewart, Lith” Edin r 
 

 

 
 
 
 
 
 
 ' . 
 
 
 
PLATE II. 
 
 Fig. i. Vertical section of Tetradium Peachii , in which tabulae are abundantly 
 developed, enlarged about fifty times. Coll. H. A. Nicholson. 
 
 Fig. i a. Another vertical section of the same, similarly enlarged, in which 
 tabulae are absent. 
 
 Fig. i b. Mass of Tetradium Peachii , showing the form of the surface, of the 
 natural size. 
 
 Fig. 2. A small example of Favosites Mullochensis , the base of which has been 
 cut away, of the natural size. No surface-characters are shown. 
 
 Fig. 2 a. Transverse section of the same, enlarged ten times. 
 
 Fig. 2 b. Vertical section of part of the same, similarly enlarged. 
 
 Fig. 3. Fragment of the base of a mass of Fistulipora favosa , of the natural 
 size. The outline shows the original size of the mass prior to sectioning. 
 
 Fig. 3 a. Portion of the weathered surface of the same, enlarged about six 
 times. The larger tubes appear black, not from shadow, but from being 
 filled with the dark matrix, while the intervening tubuli are filled with 
 calcite. 
 
 Fig. 3 b. Portion of a transverse section of the same, enlarged twenty-five 
 times. 
 
 Fig. 3 c. Longitudinal section of the same, similarly enlarged. 
 
H. Alleyn e Nicholson, del 
 
 Plate II. 
 
 Berjean, Mh. 
 
 G-. Water ston, Sons k Stewart, LitH 5 Edin* 
 
 •M&iteA 'ZBl 
 
 •••i 
 
 
 & 
 
 a 8 
 
 t«s 
 
 
 
 
 3. a 
 
 
 ^.c 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 * 
 
 
 
 . 
 
 
 
 
 
 
 
 
 
 
PLATE III. 
 
 Fig. i. A specimen of Fistulipora (?) pilula , of the natural size, viewed from 
 one side. 
 
 Fig. i a. Small portion of the transverse section of the same, enlarged about 
 twenty-five times. 
 
 Fig. i. b. Portion of the vertical section of the same, enlarged about twelve 
 times. 
 
 Fig. 2. Fragment of Chcetetes , sp., of the natural size. 
 
 Fig. 2 a. Part of the transverse section of the same, enlarged ten times. 
 
 Fig. 2 b. Part of the vertical section of the same, similarly enlarged. 
 
 Fig. 3. Under surface of the epithecal plate of a small example of Pinacopora 
 Gray , of the natural size. 
 
 Fig. 3 a. Upper surface of the epithecal plate of another specimen of the same, 
 from which all the corallites have been denuded, except a few casts on 
 the extreme margin, — of the natural size. 
 
 Fig. 3 b. Upper surface of another specimen of the same, in which the bases of 
 a number of the corallites are still left adherent to the epithecal plate, — of 
 the natural size. 
 
 Fig. 3 c. Vertical section across the corallum of another specimen of the same, 
 imperfect at the sides, — of the natural size. 
 
 Fig. 3 d. Horizontal section across the corallites of another specimen of the 
 same, enlarged about twenty times. 
 
 Fig. 3 e. Vertical section through part of the corallum of another specimen of 
 the same, enlarged about ten times. In this and the preceding figure the 
 large-sized corallites are lettered p , while the intervening tabulate tubes are 
 lettered t. 
 
 Fig. 3 f. Cast of the upper surface of a large specimen of Pinacopora Grayensis. 
 
 Fig. 3 g. Portion of the cast, enlarged five times. The short fluted columns in 
 this are casts of the larger corallites, while the intervening spaces were 
 originally occupied by the smaller tubes. 
 
 Fig. 3 h. Portion of a corallum which has naturally split in two along a 
 horizontal plane, showing the corallites embedded in the dark matrix, 
 — enlarged five times. 
 
 Fig. 3 i. Portion of a vertical section of corallum, similarly embedded in matrix, 
 and similarly enlarged. 
 
 Fig. 3 j. Portion of the surface of a gutta-percha mould of the natural cast of 
 Pinacopora Grayensis , showing the calices, — enlarged five times. 
 
H Alleyn e Nicholson, del 
 
 Plate III 
 
 C.Berjeau, lith. 
 
 G. VraterstoTi, Sons k Stewart, Lith rs Edm T 
 


 
 
 ■ 
 
 
 ' 
 
 
 
 - * 
 
 . 
 
 
PLATE IV. 
 
 Fig. i. Portion of the surface of Thecostegiies (?) Scoticus, enlarged five times. 
 
 Fig. i a. Portion of a slice of the same, taken parallel with the surface, en- 
 larged ten times, showing the calices, with their rudimentary septa. The 
 calices are filled with the dark-coloured matrix, and as the section inter- 
 sects the corallites obliquely, the walls of the tubes are brought into view. 
 
 Fig. i b. Portion of a vertical section of the same, enlarged ten times. The 
 section traverses on one side the exterior of the corallum, and the sur- 
 rounding matrix is seen to have penetrated to some extent into some of 
 the tubes. 
 
 F'ig. 2. Portion of the transverse section of Stylarcea occidentalism enlarged 
 twenty times, showing two calices, and part of a third, with their colu- 
 mellae, and the reticulate structure of the coenenchyma. Viewed by trans- 
 mitted light. Coll. H. A. Nicholson. 
 
 Fig. 2 a. Portion of the same section as the preceding, enlarged ten times, and 
 viewed on a dark background. 
 
 Fig. 2 b. Part of a vertical section of Stylarcea occidentalism enlarged ten times, 
 showing tabulae. The columella is shown in parts of the tubes. 
 
 Fig. 3. Portion of a transverse section of- Protarcea vetusta , from the Cincin- 
 nati group of Ohio, viewed on a dark background, and enlarged ten times. 
 The circular light-spaces in the floors of the calices are sections of tuber- 
 cles which rise from the bottom of the cup, and project into the visceral 
 chamber. Coll. H. A. Nicholson. 
 
 F"ig. 3 a. Vertical section of Protarcea vetusta, enlarged, and shown in outline. 
 In the floor of two of the calices is seen a predominant tubercle, which 
 may represent a rudimentary columella. Coll. H. A. Nicholson. 
 
 Fig. 4. Fragment of a branched specimen of Heliolites Grayi, Edw. and H., 
 of the nat. size. 
 
 Fig. 4 a. Portion of the transverse section of the branch of another specimen 
 of the same, enlarged about five times, showing parts of two successive 
 layers of growth — the lower layer exhibiting sections of the calices and 
 smaller tubes. Between the two layers there exists an in-filling of the 
 dark matrix of the surrounding rock. 
 
H.Alleyne Nicholson, del. 
 
 Plate IV. 
 
 C. Berjeau, lith. 
 
 0. Water ston, Sons &. Stewart, Lith 1 .? Edin? 
 

 
 
 
 
 
 
 . 
 
 . 
 
 
 
 
 
 
 
 
 
 
 ■ 
 
 
 
 
 
PLATE V. 
 
 Fig. i. Part of a thin transverse section (the best of many made) of Hehoiites 
 Grayi , Edw. & H. (?), enlarged nearly twenty times. 
 
 Fig. 2. Ah average example of Calostylis Lindstromi, Nich. and Eth., of the 
 natural size. 
 
 Fig. 2 a. Another example of the same, showing the base of a lateral bud, 
 enlarged two diameters. 
 
 Fig. 2 h. Transverse section of the same, enlarged six times. 
 
 Fig. 2 c. Portion of a longitudinal section of the same, enlarged six times, 
 showing the trabecular sclerenchyma, the central spongy columellar mass, 
 with imperfect tabulae crossing the lateral spaces. 
 
 Fig. 3. Thin section across part of a colony of Sti'eptelasma aggregation, Nich. 
 and Eth., of the natural size. Several of the corallites are seen in process 
 of division. 
 
 Fig. 3 a. A single corallite of the same, giving off young corallites from its oral 
 extremity, of the natural size. 
 
 Fig. 3 b. Transverse section of a corallite of the same, enlarged about eight 
 times, showing the thick false wall, the two orders of septa, and the union 
 of some of the primary septa with a central trabecular columella. In this 
 particular corallite no dissepiments can be detected. 
 
 Fig. 3 c. Longitudinal section of a corallite of the same, enlarged eight times, 
 showing the thick wall, the well-developed tabulae, and the columella. 
 
 Fig. 4. Fragment of a full-grown specimen of Streptelasma Craigensis , M‘Coy, 
 sp., viewed sideways, of the natural size. The specimen shows, more 
 markedly than many, the close-set and conspicuous annulations of growth 
 of this species. 
 
 Fig. 4 a. Transverse section of a small example of the same, enlarged four 
 times, showing the characters of the pseudo-columella, septa, and dissepi- 
 ments. The sides of the section are broken away, so that the false wall is 
 imperfect. 
 
 Fig. 4 b. Long section of a small example of the same, enlarged four times, 
 showing the false wall, the tabulae, and the pseudo-columella. 
 
 Fig. 4 c. A small specimen, supposed to belong to S. Craigensis , M‘Coy, sp., 
 with which it agrees in internal structure, but consisting of three corallites, 
 apparently produced by fission. 
 
2. as 
 
 H. Alleyne 'Nicholson, 3el. 
 
 Plate Y. 
 
 3. S erjeau, lith. 
 
 C. Water ston, Sons- it Stewart, Lith.*? Edin r 
 
 3.b. 
 
 Z.c 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 > 
 
 ' 
 
 
 
 
 
 
 - . 
 
 . 
 
 . 
 
 • r 
 
 . . 
 
 
 
 
 
 
PLATE VI. 
 
 Fig. i. Side view of one of the larger specimens of Streptelasma Europceum, 
 Roemer, the upper part of which is crushed in, — of the natural size. 
 
 Fig. i a. A smaller example of the same, of the natural size. 
 
 Fig. i b. Cross-section of another specimen of the same, enlarged rather more 
 than three times, showing the central reticulate pseudo-columella. 
 
 Fig. 2. An average specimen of Lindstromia subduplicata , M‘Coy, sp., viewed 
 from the front, of the natural size. The upper part of the specimen being 
 crushed in, its apparent width is unnatural, .and it looks more widely tur- 
 binate than it really is. 
 
 Fig. 2 a. A smaller specimen of the same, viewed sideways, of the natural size. 
 
 Fig. 2 b. Vertical section of the same, enlarged about four times, showing the 
 
 deep calice, the fasciculate structure of the pseudo-columella, and two or 
 three imperfect tabulae. 
 
 Fig. 2 c. Vertical section of another specimen of the same, enlarged four times, 
 showing a great upward prolongation of the columella into the bottom 
 of the calice, and the nearly solid filling of the bottom of the visceral 
 chamber. 
 
 Fig. 2 d. Transverse section of another example of the same, enlarged five 
 
 times, showing the union of the larger septa with the great central mass 
 
 of the columella. 
 
 Fig. 2 e. A small portion of the outer surface of the cast of the same species, 
 showing the slight crenulation of the laminae representing the interseptal 
 loculi, which is present in ordinary examples. Enlarged. 
 
 Fig. 2 f. Small portion of the cast of the supposed variety of the same (var. 
 crenulata , M‘Coy) showing the deep crenulation of the laminae representing 
 the filled-up interseptal loculi. Enlarged. 
 
 Fig. 3. Cross-section of Streptelas 7 na (?) cequi sulcatum, M‘Coy, sp., enlarged four 
 times, showing the twisted and inosculating septa, the presence of second- 
 ary septa, and the few dissepiments. The centre of the visceral chamber 
 is filled up in reality with the matrix, but there are indications of a reticu- 
 lated pseudo-columella. The light spaces represent the original cavities 
 of the corallum. 
 
 Fig. 4. A medium-sized example of Lindstromia Icevis , Nich. and Eth., viewed 
 dorsally and in profile, of the natural size. 
 
 Fig. 4 a. Side view of a very large specimen of the same, of the natural size. 
 
 Fig. 4 b. Vertical section of the same, enlarged five times, showing the central 
 columellar mass, the deep calice, and the arched ascending tabulae. 
 
 Fig. 4 c. Vertical section of another example of the same, enlarged similarly. 
 
 Fig. 4 d. Transverse section of the same, close above the base, enlarged five 
 times, showing the union of the larger septa with the central columellar 
 mass. 
 
 Fig. 4 e. Transverse section of another specimen of the same, taken just below 
 the floor of the calice, enlarged five times, showing the decrease in pro- 
 ceeding upwards of the size of the columella. 
 
Plate VI 
 
 H.A'lleyne Nicholson, del 
 
 C.Berjeau, lith. 
 
 Wateiston, Sons 2c Stewart, Litl£ s EcIiTL* 
 
PLATE VI. 
 
 Fig. i. Side view of one of the larger specimens of Streptelasma Europceum , 
 Roemer, the upper part of which is crushed in, — of the natural size. 
 
 Fig. i a. A smaller example of the same, of the natural size. 
 
 Fig. i b. Cross-section of another specimen of the same, enlarged rather more 
 than three times, showing the central reticulate pseudo-columella. 
 
 Fig. 2. An average specimen of Lindstromia subduplicata , M‘Coy, sp., viewed 
 from the front, of the natural size. The upper part of the specimen being 
 crushed in, its apparent width is unnatural, .and it looks more widely tur- 
 binate than it really is. 
 
 Fig. 2 a. A smaller specimen of the same, viewed sideways, of the natural size. 
 
 Fig. 2 b. Vertical section of the same, enlarged about four times, showing the 
 deep calice, the fasciculate structure of the pseudo-columella, and two or 
 three imperfect tabulae. 
 
 Fig. 2 c. Vertical section of another specimen of the same, enlarged four times, 
 showing a great upward prolongation of the columella into the bottom 
 of the calice, and the nearly solid filling of the bottom of the visceral 
 chamber. 
 
 Fig. 2 d. Transverse section of another example of the same, enlarged five 
 times, showing the union of the larger septa with the great central mass 
 of the columella. 
 
 Fig. 2 e. A small portion of the outer surface of the cast of the same species, 
 showing the slight crenulation of the laminae representing the interseptal 
 loculi, which is present in ordinary examples. Enlarged. 
 
 Fig. 2 f Small portion of the cast of the supposed variety of the same (var. 
 crenulata, M‘Coy) showing the deep crenulation of the laminae representing 
 the filled-up interseptal loculi. Enlarged. 
 
 Fig. 3. Cross-section of Streptelasma (?) cequisulcatum , M‘Coy, sp., enlarged four 
 times, showing the twisted and inosculating septa, the presence of second- 
 ary septa, and the few dissepiments. The centre of the visceral chamber 
 is filled up in reality with the matrix, but there are indications of a reticu- 
 lated pseudo-colurnella. The light spaces represent the original cavities 
 of the corallum. 
 
 Fig. 4. A medium-sized example of Lindstromia Icevis , Nich. and Eth., viewed 
 dorsally and in profile, of the natural size. 
 
 Fig. 4 a. Side view of a very large specimen of the same, of the natural size. 
 
 Fig. 4 b. Vertical section of the same, enlarged five times, showing the central 
 columellar mass, the deep calice, and the arched ascending tabulae. 
 
 Fig. 4 c. Vertical section of another example of the same, enlarged similarly. 
 
 Fig. 4 d. Transverse section of the same, close above the base, enlarged five 
 times, showing the union of the larger septa with the central columellar 
 mass. 
 
 Fig. 4 e. Transverse section of another specimen of the same, taken just below 
 the floor of the calice, enlarged five times, showing the decrease in pro- 
 ceeding upwards of the size of the columella. 
 
Plate VI 
 
 H.Alleyno Nicholson, del 
 
 miml 
 
 C.Berjeau, lith. 
 
 Wateistou, Sons & Stewart, LitK s E din 2 
 
PLATE VII. 
 
 Phacops Brongniarti, Portlock, p. 99. 
 
 Fig. 1. Exceedingly fine cast of a specimen from Ardmillan Brae ( Coll. Mus . 
 Pract. Geology ) ; x 2. 
 
 Fig. 2. Decorticated example from Mulloch Hill quarry, with half the head 
 only preserved; x 2. 
 
 Phacops truncato-caudatus, Portlock , p. 99. 
 
 Fig. 3. Decorticated specimen of the pygidium and a portion of the thorax ; 
 
 small transverse striae are well shown. Drummuck Quarry ; x 5. 
 
 Fig. 4. Similar example from same locality ; x 2. 
 
 Cheirurus gelasinosus, Portlock (?), p. 100. 
 
 Fig. 5. An example showing the glabella and its furrows, a portion of the cheek 
 and neck-segment. Balcletchie ; x 2. 
 
 Fig. 6. Another example from the same locality, showing a larger portion of 
 the cheek and neck-segment ; x 2. 
 
 Cheirurus clavifrons, Dalman (?), p. 101.' 
 
 Fig. 7. A fine glabella, placed somewhat on one side, showing the three furrows, 
 the posterior quite circumscribing the posterior lobe ; the scrobiculae of 
 the cheeks are also visible. Drummuck quarry — nat. size. 
 
 Fig. 8. The same specimen, front view — nat. size. Fig. 8 a, a portion of the 
 roughened surface highly magnified. 
 
 Cheirurus, sp. ind., p. 104. 
 
 Fig. 9. A portion of a glabella, allied to, but slightly different from, C. clavi- 
 frons (?). The glabella is broken-off across the posterior furrows. Drum- 
 muck — nat. size. Fig. 9 a , ornamentation magnified. 
 
P late VII. — continued. 
 
 Cheirurus trispinosus, Young , p. 105. 
 
 Fig. 10. A glabella, with the ornamentation preserved, the three spines in place, 
 the middle one being broken off, and the position of the posterior lobe and 
 furrow shown. Penkill — nat. size. 
 
 Fig. 11. A crushed head, showing the three spines projecting from the matrix. 
 Penkill ; x 2. 
 
 Fig. 12. A part of a free-cheek, showing the ornamentation and the thickened 
 anterior margin. Penkill — nat. size. 
 
 Fig. 13. A somewhat crushed head from the same locality, exhibiting the genal 
 spines in a fine state of preservation, and the broken base of the cervical 
 spine — nat. size. Fig. 13 a, the right spine enlarged three times. 
 
 Fig. 14. A glabella, with some of the original integument remaining, the basal 
 and ocular furrows visible and basal lobes. The bases of the genal spines 
 are preserved, but not the cervical. Penkill — nat. size. 
 
 Fig. 15. Another glabella seen from behind, in which the neck-segment and 
 base of its spine are exceedingly well shown, as also are the circumscribed 
 basal lobes and the ornamentation. Penkill — nat. size. 
 
 Fig. 16. The same seen from the front, showing the blunt anterior of the gla- 
 bella — nat. size. 
 
 Fig. 17. A restoration of the head, copied from Dr J. Young’s figure ( Proc . Nat. 
 Hist. Soc. Glasgow , I., pt. 1, t. 1, f. 6 a). 
 
 .Cheirurus, sp. ind ., p. 107. 
 
 Fig. 18. Portion of thorax and pygidium of an undetermined species from 
 Drum muck ; x 3. 
 
 Cheirurus (?), sp. ind ., p. 107. 
 
 Fig. 19. A minute form from Balcletchie, showing only two glabella furrows ; 
 
 x 4. 
 
 Sph^erexochus mirus, Beyrich , p. 107. 
 
 Fig. 20. Glabella, exhibiting the characteristic form and lobes of this species, 
 from the coarse-grained ash, or fine conglomerate, of Balcletchie — nat. size. 
 
Plate VII. 
 
 Waterston, Sons &. Stewart, LithT? Edin 1 
 
 ■ 
 
 s;«&i frS 8 °- 
 
 G. Berjeau, lith. 
 
PLATE VIII. 
 
 Encrinurus punCtatus, Brunnich , var. arenaceus, Salter. p. 109. 
 
 Fig. 1. A nearly complete specimen from Penkill; the tubercules on the head 
 and tail are well preserved, and also the eyes ; x 3. 
 
 Fig. 2. A well-preserved decorticated specimen from Mulloch; x 3. 
 
 Fig. 3. A pygidium from Penkill ; x 2. 
 
 Fig. 4. A pygidium from the Craighead limestone ; x. 3. 
 
 Cybele rugosa, Portlock , p. 112. 
 
 Fig. 5. An almost perfect example from Drummuck, showing the chief charac- 
 ters of the species ; it is a little imperfect about the tail, but on comparison 
 with fig. 6, the features will be found to be identical — nat. size. 
 
 Fig. 6. A well-preserved cast of a typical pygidium from Drummuck — <2, nat. 
 size; b , x 2. 
 
 Fig. 7. A coiled and decorticated specimen split in half longitudinally; the 
 course of the facial suture and the peculiar glabella lobes are well shown. 
 Drummuck; x 2. 
 
 Dindymene cordai, Eth. and Nich., p. 115. 
 
 Fig. 8. A well-preserved example, minus the. head, from Drummuck. The 
 characteristic tail is plainly exhibited ; x 2. 
 
 Staurocephalus (?) unicus, Wyv. Thomson , p. 118. 
 
 Fig. 9. The cephalic shield with the glabella removed — a cast from Balcletchie ; 
 x 2. 
 
 Fig. 10. An impression of an almost perfect specimen from the same locality; 
 the glabella has been accidentally pressed down upon the other portions ; 
 x 2. 
 
 Fig. 11. The type of St. Maclareni (Wyv. Thomson) ; cast of the tail from Pen- 
 whapple Glen ( Coll. Mus. Pract. Geology) — nat. size. 
 
 Fig. 12. A portion of the cephalic shield, with the integument remaining; the 
 relative positions of the genal and anterior spines are exhibited. Bal- 
 cletchie ; x 2. 
 
Plate VII I . — continued. 
 
 Fig. 13. Two heads in contact, in both of which the frontal lobe, eyes, and 
 cephalic spines are well exhibited. Penkill ; x 2. Fig. 13 a portion of 
 the ornamentation of the frontal lobe highly magnified. 
 
 Fig. 1 4. A cephalic shield partly protruding from the matrix, in which the 
 frontal lobe is visible, with a portion of its ornamentation ; the eye in situ , 
 and the broken bases of the three spines on the left side. Balcletchie ; 
 x 2. Fig. 14 a, the eye enlarged. 
 
 Figs. 15 and 16. Two isolated frontal lobes of the glabella from Balcletchie — 
 nat. size. 
 
 Acidaspis Lalage, Wyv. Thomson , p. 121. 
 
 Fig. 17. An example, with the portions of the head and thorax preserved, in- 
 cluding the thoracic spines. , Balcletchie ; x 3. 
 
 Figs. 18-22. The head or cephalic shield in various ■ states of preservation, with 
 and without the spines preserved. Balcletchie. Figs. 18,21,22; x 3. 
 Fig. 19; x 5. 
 
 Acidaspis hystrix, Wyv. Thoinson, p. 123. 
 
 Fig. 23. A cast of the thorax and pygidium from Balcletchie, showing the gran- 
 ulated surface and spines ; x 3. 
 
 Fig. 24. An isolated pygidium from Balcletchie ; x 5. 
 
 Fig. 25. Another example, showing the pygidium, and a part of the thorax, 
 spines, granular ornamentation, &c. .. Balcletchie ; x 5. 
 
 Acidaspis Graya:, R. Etheridge, jun., p. 126. 
 
 Fig. 26. A decorticated and somewhat crushed specimen, showing the general 
 characters of the species. Balcletchie ; x 2. 
 
V 
 
 
 Plate YIU. 
 
 C.Berjeau, lith.. 
 
 Water stem, Sons & Stewart, LitliT? Edm 1 
 

PLATE IX. 
 
 Acidaspis Gray^e, P. Etheridge, jun., p. 126. 
 
 Figs. 1 and 3. Casts of the pygidium and portion of the thorax, with the den- 
 ticulated spines in place, and also the reticulate surface of the former. 
 Balcletchie. Figs. 1 x, 2 ; fig. 3 ; x 1^ times. 
 
 Figs. 2, 4, and 6. Various specimens of the pygidium ; in figs. 2 and 4 the 
 spines are fifteen in number, but in fig. 6 there are sixteen. Fig. 4 a, one 
 of the spines magnified, showing the denticles. Balcletchie. Figs, 2, 4, 
 and 6 ; x 2. Fig. 4 a ; x 5. 
 
 Fig. 5. A cast of a few thoracic segments, with spines attached ; the positions 
 of the denticles are shown as small holes in the casts of the spines. Bal- 
 cletchie. Fig. 5 a; x 2. Fig. 5 b ; x 10 times. 
 
 Fig. 7. A portion of a cephalic shield, with the genal spine, probably of this 
 species. Balcletchie ; x 3. 
 
 Lichas Barrandei, Fletcher (?), p. 132. 
 
 Fig. 8. An impression in yellow schist of a well-preserved pygidium, showing 
 the extended axis, lateral flaps, and ornamentation. Mulloch Hill ( Coll . 
 Mus. Pract. Geology) — nat. size. 
 
 Lichas Hibernicus, Portlock , p. 133. 
 
 Fig. 9. Forehead and side lobes of a large glabella, highly ornamented, and 
 with a portion of the neck-segment preserved. Craighead — nat size. Fig. 
 
 9 a, ornamentation highly magnified. 
 
 Fig. 10. A somewhat crushed cast, showing similar features to the last, and 
 also a portion of one of the accessory lobes. Balcletchie — nat. size. 
 
 Lichas Grayii, Fletcher (?), p. 134. 
 
 Fig. 11. A decorticated example of the forehead-lobe, two side-lobes, one of 
 the accessory lobes, and the neck-lobe. Mulloch Hill ; x 2. 
 
 Fig. .12. The same specimen seen from the front, showing the anterior portion 
 of the front lobe, and the two side-lobes ; x 2. 
 
Plate I X . — continued. 
 
 Lichas, sp. ind. y p. 135. 
 
 Fig. 13. Part of the forehead-lobe, one of the lateral lobes, the eye-lobe, and 
 eye of a large species of Lichas. Drummuck — nat. size. 
 
 Fig. 14. Opposite side of the same specimen, showing a part of the hypostome 
 and one of its wings — nat. size. 
 
 Nidulites favus, Salter , p. 18. 
 
 Fig. 15. Portion of a cavity left by a specimen resembling fig. 16, showing the 
 convex casts of the cups, with here and there the papillae formed by the 
 casts of the styliform processes — nat. size. Mulloch Hill. 
 
 Fig. 16. Half of a globose or pyriform (?) specimen, being the internal mould 
 of an individual from which the true integument has disappeared, leaving 
 the characteristic hexagonal or pentagonal cups, with the styliform pits or 
 depressions in the centre — nat. size. Mulloch Hill. 
 
 Fig. 17. Portion of another globose example, showing the cup-casts and styli- 
 form pits ; x 4. Mulloch Hill. 
 
 Fig. 18. Portion of a specimen similar to fig. 15, showing the irregular form of 
 the cups, the central papillae, and the surface peeling-off concentrically; 
 x 4. Mulloch Hill. 
 
 Fig. 19. Showing the cups of the globose body of Nidulites similar to fig. 16, in 
 apposition with their convex casts, such as fig. 15, leaving between them a 
 narrow space from which has been removed the true integument or shell of 
 the organism ; x 2. Mulloch Hill. 
 
 Fig. 20. A transparent microscopic section obtained from a slice taken from 
 fig. 19, where preserved in the matrix as a series of small, hollow calcareous 
 cups, the general convexity of the body being clearly discernible ; x 2. 
 Mulloch Hill. 
 
 Fig. 21. Portion of a specimen similar to fig. 15, exhibiting a depression 
 (? central), with the remains of a small plug or peduncle, and spreading 
 from it fibres resembling an investing membrane ; x 4. Upper Llandovery, 
 Haverford West ( Coll. Mus. Pract. Geology , London). 
 
 Fig. 22. An almost perfect globose specimen similar to fig. 15, but in which the 
 cup-casts have been worn down, leaving spaces unoccupied representing 
 the true walls. Mulloch Hill — nat. size. A few of the plates are enlarged 
 4 diameters. 
 
 Saccammina Carteri, Brady , p. 21. 
 
 Fig. 23. Portion of a slice of limestone showing sections of S. Carteri. Tra- 
 mitchell; x 5 {Coll. H. A. Nicholson). 
 
 Girvanella problematica, N. and p. 23. 
 
 Fig. 24. Portion of a slice of limestone showing the tubes of G. problematica. 
 Tramitchell; x 50 {Coll. H. A. Nicholson). 
 
Plate IX. 
 
 
 ... ,o«v-- 
 
 %&(«& 
 
 fS?&4 
 
 
 -v 
 
 C-Berjeattili-lih. 
 
 Waterston, Sons k Stewart, Lith” Edint