TABULATE CORALS 
 
 OF THE 
 
 PALEOZOIC PERIOD 
 
ON THE 
 
 STRUCTURE AND AFFINITIES 
 
 OF THE 
 
 TABULATE CORALS 
 
 OF THE 
 
 PALAEOZOIC PERIOD 
 
 WITH CRITICAL DESCRIPTIONS OF 
 ILLUSTRATIVE SPECIES 
 
 BY 
 
 H. ALLEYNE NICHOLSON 
 
 M.D., D.Sc., F.R.S.E., F.L.S. 
 
 PROFESSOR OF NATURAL HISTORY IN THE 
 UNIVERSITY OF ST ANDREWS 
 
 WILLIAM BLACKWOOD AND SONS 
 
 EDINBURGH AND LONDON 
 
 MDCCCLXXIX 
 
A/5- 
 
 TO 
 
 J. N. 
 
 IN GRATEFUL ACKNOWLEDGMENT 
 
 OF IMMEMORIAL LOVE, OF PRICELESS COUNSEL, 
 
 AND OF UNFAILING HELP, 
 
 Ejjts SHorfc 
 
 IS AFFECTIONATELY INSCRIBED BY 
 THE AUTHOR. 
 
 754 
 
PREFACE. 
 
 THE present work is a record of a series of researches which I 
 have been engaged in carrying out, with intermissions, for some 
 years, into the minute structure and relations of the Palaeozoic 
 " Tabulate Corals." The space, means of illustration, and 
 leisure at my command have not permitted me to make this an 
 even approximately exhaustive account of the numerous and 
 interesting forms of Corals embraced by Milne-Edwards and 
 Jules Haime, under the name of " Zoantharia Tabulata." I 
 have, therefore, restricted myself, in the meanwhile, to the 
 elucidation of the anatomy of the principal Palaeozoic genera of 
 the " Tabulata," which I have been able to personally investi- 
 gate ; and I have usually given in addition short descriptions 
 of one or more of the species of each genus, as illustrative of 
 the structural type under consideration. 
 
 The general result of my investigations is that I am able 
 to corroborate the views of Verrill and Lindstrom as to the 
 necessity of abolishing the " Tabulata " as a distinct and 
 separate division of the Zoantharia. I have also been led to 
 conclude that under the old name of "Tabulata" there are 
 included at least twelve distinct groups of corals, and that, 
 while some of these are Hydrozoa, and others are true Zoan- 
 
viii PREFACE. 
 
 tharia, a large number may be referred, with greater or less 
 certainty, to the order of the Alcyonaria a few forms being of 
 quite uncertain affinities. I have not, however, been induced 
 to think that the so-called "Tabulate Corals" are, to any 
 extent, referable to the Polyzoa ; 1 and I do not think that any 
 but the aberrant Milleporidce can be at present regarded as 
 possessing Hydrozoan affinities. On many minor points I 
 have been led to form conclusions different from those that are 
 ordinarily held, and I have no right to expect that these will 
 be in all cases immediately or generally accepted ; while I 
 have the certainty that many of the results which I have 
 
 1 Since this work has passed through the press, Professor Busk has published a 
 description and figures of the recent species of Heteropora referred to on p. 256, 
 giving to it the name of H. Neozelanica (Journ. Linn. Soc., vol. xiv., p. 724). Two 
 other living species have also been described by Mr W. Waters (Journ. Roy. Mic 
 Soc., June 1879). Mr Busk has shown that the walls of the zocecia and interstitial 
 tubes (" cancelli ") of H. Neozelanica are perforated by minute pores, a phenomenon 
 not unknown in species of the genus now extinct. In the comparatively limited 
 investigation of H. Neozelanica made by me, these pores escaped notice. The con- 
 necting-pores just alluded to certainly admit of a comparison with the "mural 
 pores " of the Favositidce, but the comparison is not much closer in their case than 
 in the instance of the pores in the walls of species of Lepralia or Alecto. Nor does 
 their similar appearance and position prove these apertures to be absolutely homo- 
 logous. At any rate the likeness between the pores of Heteropora and the mural 
 pores of the Favositida is, to say the very least, no closer than the resemblance 
 between the latter and the apertures in the walls of such undoubted Actinozoa as 
 Forties and Alveopora. Giving due weight to this last consideration, and combining 
 this with the fact that the true zocecia of Heteropora do not appear to be "tabulate," 
 while the typical " Tabulata " exhibit so many and such important points of affinity 
 with unquestionable living corals, both Alcyonarians and Zoantharians, I do not at 
 present feel inclined to alter the opinion which I have formed as to the Ccelenterate 
 nature of the Favositidce, the CJuztetidce, and the Monticuliporidce. At the same 
 time, it is undeniable that there is a remarkably close resemblance between some of 
 these forms (and especially the Monticuliporoids) and Heteropora. This resemblance 
 is enhanced by the fact that one of the species of Heteropora described by Mr 
 Waters exhibits the usually chitinous surface-pellicle in a calcified and thickened 
 condition, thus reminding us forcibly of the state of parts in some of the species of 
 Favosites, and in various of the Monticuliporidce. These resemblances, as above 
 pointed out, are counterbalanced by weighty points of dissimilarity; but they are 
 more than sufficient to make us await with the greatest interest any observations 
 upon the animal of Heteropora. 
 
PREFACE. ix 
 
 obtained will not be arrived at except by those who are willing 
 to adopt the modes of investigation here followed. l 
 
 To those acquainted with the subject, it is unnecessary for 
 me to point out that I have been greatly assisted in the task I 
 have attempted by the previous labours of Milne- Edwards and 
 Haime, Martin Duncan, Lindstrom, and other distinguished 
 palaeontologists, and especially by the investigations of Louis 
 Agassiz, Verrill, and Moseley into the structure and relations 
 of the few existing Tabulate Corals. At the same time, almost 
 all the actual facts recorded in this volume have been verified 
 or worked out by myself, and any facts which I have not per- 
 sonally been able to test are invariably accredited to their 
 original authority. 
 
 In this connection I should further add that I have not 
 been able to refer to the fifth volume of the ' Palaeontology of 
 New York,' by Professor James Hall, which, I believe, con- 
 tains numerous illustrations of Palaeozoic Tabulate Corals ; 
 the cause of my inability to consult this important work being 
 that, after repeated attempts, I found it impossible to obtain a 
 copy through the ordinary channels. Under these circum- 
 stances I can only leave it to my fellow workers to decide how 
 far a scientific work, which apparently cannot be obtained by 
 purchase, is to be regarded as actually published ; and in 
 making this remark I need hardly say that I am merely 
 anxious to account for an apparent omission on my part, 
 and do not wish to express any opinion upon the method in 
 which Professor Hall has seen fit to bring out his work. 2 
 
 1 In this connection I may specially refer the reader to the remarks made at p. 
 270 as to the proper method of sectioning the coralla of the Tabulate Corals, with a 
 view to microscopic examination. 
 
 s The work here referred to appeared, I believe, in 1877. With regard to its 
 publication, Professor C. A. White states (Bibliography of N. Amer., Invert. Pal., p. 
 38, 1878) that he had been unable to consult a copy, "search for it in the libraries 
 of Washington and Philadelphia having been unsuccessful." He adds : " Only one 
 hundred copies are reported to have been published." 
 
x PREFACE. 
 
 The material upon which this work is based is principally, 
 though not exclusively, contained in the extensive collections 
 of Corals which I have made from the Palaeozoic formations 
 of Britain, the Continent of Europe, and North America ; but 
 I have also had the opportunity of consulting the collections of 
 the British Museum, the Museum of Practical Geology, and 
 the Edinburgh Museum of Science and Art. The method of 
 investigation which I have adopted has been largely that of 
 microscopic sections, and the present work is, therefore, much 
 more extensively occupied with detailed descriptions of minute 
 structure than has been usual in treatises or memoirs dealing 
 with the fossil Corals. For the same reason I have been more 
 concerned to investigate the actual anatomy and systematic 
 relations of even perfectly well known types, than to describe 
 new forms or to discuss difficult and disputed points of specific 
 determination. The necessary sections, with few exceptions, 
 have been personally prepared by myself, and the illustrations 
 of microscopic structure are from drawings made by the 
 camera lucida. Unless otherwise explicitly acknowledged, 
 all the illustrations, whether in the text or the plates, are from 
 original drawings of my own ; and I have to return my best 
 thanks to my friend Mr Berjeau for the care and fidelity with 
 which he has reproduced these on wood and stone. 
 
 I have, finally, to express my gratitude for the varied and 
 valuable assistance which has been freely accorded to me by 
 my friends Mr R. Etheridge, F.R.S., Mr R. Etheridge, jun., 
 F.G.S., Mr George Jennings Hinde, F.G.S., Dr Gustav 
 Lindstrom, and Dr Ramsay H. Traquair, F.R.S.E. 
 
 UNITED COLLEGE, ST ANDREWS, 
 September 10, 1879. 
 
LIST OF ILLUSTRATIONS, 
 
 ENGRAVINGS. 
 
 FIG. PAGE 
 
 1. Millepora alcicornis, Forsk., .... 13 
 
 2. The animal of Millepora nodosa. (After Moseley), . . 14 
 
 3. Pocillopora aspera, var. lata, Verrill. (After Dana), , . 15 
 
 4. Favosites favosa, Goldf. ; and F. Got/ilandica, Lam., . . 16 
 
 5. Syringopora retiformis. Bill. (After Billings), . 18 
 
 6. verticillata, Goldf. (After Billings), . . . 18 
 
 7. Dalmani, Bill. (After Billings), . . . 18 
 
 8. Aulopora tubceformis, Goldf.; and Cladochonus (Pyrgia) Michelini, 
 
 Edw. and H. (After Goldfuss, and Edwards and Haime), , . 20 
 
 9. Haly sites catenularia, Linn. ; and H. agglomerata, Hall. (Original), 22 
 
 10. Tetradiiim minus, Safford. (Original), .... 23 
 
 11. Heliolites megastoma, M'Coy. (Original), .... 26 
 
 12. Labechia conferta, Edw. and H. (Original), . . . 28 
 
 13. Alveopora spongiosa, Dana. (After Dana), . . . 32 
 
 14. Forms of Favosites Gothlandica, Lam. (Original), . - . 48 
 
 15. Favosites hemispherica^ Yand. and Shum. (After Billings), . 67 
 
 1 6. Pachypora Fischeri, Bill. (Original), . 93 
 
 17. Pachypora frondosa, Nich. (Original), . . 95 
 
 1 8. Striatopora flexuosa, Hall. (After Hall), ... 98 
 
 19. Romingeria umbellifera, Bill. (Original), . . . 115 
 
 20. Calices of Alveolites sulorbicularis, Lam. (After Goldfuss), . 127 
 
 21. Michelinia convexa, D'Orb. (After Billings), . . .140 
 
 22. Pleiirodictyum problematicum, Goldf. (After Roemer, and Edwards 
 
 and Haime); and P. stylophorum, Eaton. (Original), . . 145 
 
 23. Diagrams of Sections of Favosites and Pleiirodictyum. (Original),. 149 
 
 24. Sections of Arceopora anstralis, Nich. and Eth., jun. (Original), . 167 
 
 25. Stenopora Jackii, Nich. and Eth., jun. (Original), . . 173 
 
 26. Sections of Stenopora ovata, Lonsd. (Original), . . .174 
 
xii LIST OF ILLUSTRATIONS. 
 
 27. Syringolites Huronensis, Hinde. (Original), *79 
 
 28. Columnaria calicina, Nich. (Original), . T 9 8 
 
 29. (?) Halli, Nich. (After Billings), 201 
 
 30. Sections of Syringopora reticulata, Goldf. (Original), 211 
 
 31. CladocJwnus Michelini, Edw. and H.; and species of Aulopora. 
 
 (Original), . 22 
 
 32. Monilopora crassa, M'Coy, sp. (Original), 224 
 
 33. Tetradium minus, Safford. (Original), . 2 33 
 
 34. Heteropora Neozelanica, Busk (Original); and H. subreticulata. 
 
 (After Reuss), .... 257 
 
 35. Sections of Monticulipora and Chcztetes. (Original), 274 
 
 36. Monticulipora moniliformis, Nich. (Original), . 279 
 
 37. Section of Monticulipora moniliformis, Nich. (Original), . 279 
 
 38. Sections of Stenopora Tasmaniensis, Lonsd. (Original), . 281 
 
 39. Sections of Fistulipom minor, M'Coy. (Original), . 307 
 
 40. Fistulipora incrassata, Nich. (Original), . 309 
 
 41. Sections of Fistulipora proporoides, Nich. (Original), . 311 
 
 42. Monticulipora (Diplotrypa} Whiteavesii, Nich. (Original), 317 
 
 43. Prasopora Gray/%, Nich. and Eth., jun. (Original), 325 
 
 44. Labechia conferta, Edw. and H. (Original), . . 33 1 
 
 PLATES. 
 
 I. Favosites Gothlandica, Lam.; and F. Forbesi, Edw. and H. 
 II. ,, Forbesi, Edw. and H.; and its varieties. 
 
 III. Forbesi, Edw. and H. ; F. hemispherica, Yand. and Shtim.; and 
 
 F. Bowerbanki, Edw. and H. 
 
 IV. ,, clausus, Rom. ; and species of Pachypora. 
 V. Species of Pachypora, Striatopora, and Trachypora. 
 
 VI. Vermipora, Alveolites, and Ccenites. 
 
 VII. Ccenites, Columnopora, and Laceripora. 
 
 VIII. Pleurodictyum, Chonostegites, and Lyopora. 
 
 IX. Stenopora, Lyopora, Nyctopora, and Billingsia. 
 
 X. ,, Columnaria, Syringopora, and Haly sites. 
 
 XL Halysites, Thecia, Propora, Lyellia, and Plasmopora. 
 
 XII. Plasmopora, Heliolites, Pinacopora, and Chcetetes. 
 
 XIII. ,, Monticulipora (Heterotrypa', Diplotrypa, and Monotrypa}. 
 
 XIV. Monticulipora (Diplotrypa and Monotrypa), and Constellaria. 
 XV. ,, Dekayia, Fistulipora, and Labechia. 
 
PALEOZOIC TABULATE CORALS. 
 
 CHAPTER I. 
 
 THE CLASSIFICATION AND AFFINITIES OF THE " TABULATE 
 
 CORALS." 
 
 THE " Ta&ulafa" as originally understood, constitute one of 
 the four primary divisions of the Zoantharian Actinozoa, as 
 laid down and defined by Milne- Edwards and Haime in their 
 great works upon the fossil Corals (Brit. Foss. Corals, Intro- 
 duction, 1850; and Polypiers Foss. des Terr. Pal., 1851). In 
 this division was included a large assemblage of Corals, ranging 
 from the Silurian period to the present day, and often of very 
 diverse structure, but characterised by the possession of well- 
 developed " walls," by the separation of the visceral cavities 
 of the corallites into distinct chambers by transverse partitions 
 or "tabulse," and by the rudimentary condition of the " septa." 
 The distinguished French zoophytologists just quoted remark 
 of this division of the Corals, that its principal character " is 
 founded on the existence of the lamellar diaphragms that close 
 the visceral chamber of the corallites at different heights, and 
 differ from the dissepiments of the Astrceidce by not being 
 dependent on the septa, and forming as many complete hori- 
 zontal divisions extending from side to side of the general. 
 
2 TABULATE CORALS. 
 
 i 
 cavity, instead of occupying only the one or two loculi. It is 
 
 also to be remembered that the septal apparatus, though more 
 or less rudimentary, has the same general mode of arrangement 
 as in the preceding sub-orders " (Aporosa and Perforata), " and 
 never presents the crucial character which we shall find in the 
 Zoantharia Rugosa" They also divide the " Tabulata " into 
 the following four families, comprising the under-mentioned 
 genera : 
 
 Fain. I. MILLEPORID^E. Corallum principally composed of a very abundant 
 ccenenchyma, distinct from the walls of the corallites, and of a tubular or 
 cellular structure. Septa not numerous ; tabulae numerous and well formed. 
 Genera Millepora, Lam.; Heliopora, De Blainv. ; Heliolites, Dana; Fistuli- 
 pora, M'Coy ; Plasmopora, Edw. and H.; Propora, Edw. and H. ; Axopora, 
 Edw. and H. ; Lobopora, Edw. and H. 
 
 Earn. II. FAVOSITID^E. Corallum essentially formed by lamellar walls, with 
 little or no coenenchyma. Visceral chambers divided by numerous and 
 well-developed complete tabulae. 
 
 Tribe i. Favositince. Corallum massive. Walls perforated. Septa rudi- 
 mentary. No coenenchyma. Genera Favosites, Lam. ; Michelinia, 
 De Kon. ; Koninckia, Edw. and H. ; Alveolites, Lam. 
 Tribe 2. Chcetetince. Corallum massive. Walls not perforated. Neither 
 septa nor ccenenchyma. Genera Chcetetes, Fischer; Dania, Edw. 
 and H ; Stenopora, Lonsd. ; and Constellaria, Dana. 
 Tribe 3. Halysitince. Corallum composed of corallites constituting verti- 
 cal laminae or fasciculi, but more or less free laterally, and united by 
 means of connecting tubes or mural expansions. Walls well developed, 
 and not porous. Septa distinct, but small. Genera Halysites, 
 Fischer; Harmodites, Fischer (subsequently abandoned for Syringo- 
 pora, Goldf.), and Thecostegites, Edw. and H. 
 
 Tribe 4. Pocilloporina. Corallum massive, gibbous, or subdendroid, 
 with thick imperforated walls, forming towards the surface an abun- 
 dant compact coenenchyma. Septa quite rudimentary. Genus 
 Poallopora, Lam. 
 
 Fam. III. SERIATOPORID/E. Corallum arborescent or bushy, with an abun- 
 dant compact ccenenchyma. Visceral chambers filling up by the growth 
 of the columella and the walls, and showing but few traces of tabulae. 
 Genera Seriatopora, Lam. ; Dendropora, Michelin ; Rhabdopora, Edw. 
 andH. 
 
 Fam. IV. THECID^E. Corallum massive, with an abundant, compact, spuri- 
 ous coenenchyma, produced by the septa becoming cemented together 
 laterally. Tabulae numerous. Genus Thecia, Edw. and H. 
 
 Various additions, modifications, and improvements in the 
 above classification of the " Tabulata" were made by Milne- 
 
CLASSIFICATION. 3 
 
 * 
 
 Edwards and Haime during the progress of their classical 
 monograph on the Fossil Corals of Britain ; many new genera 
 were added ; and the tribe of the Stylophyllince, to include the 
 curious Cretaceous genus Stylophyllum, Reuss, was inserted 
 in the family of the FavositicUe. Most of the changes here 
 indicated, which it would be needless to point out in detail, 
 are to be found incorporated in the systematic account of the 
 " Tabulata" given by Milne-Edwards in his masterly ' Histoire 
 Naturelle des Coralliaires' (vol. iii., 1860). 
 
 The first serious attack upon the classification of Milne-Ed- 
 wards and Haime, and upon the position of the " Tafiutata" was 
 made by Professor Louis Agassiz, who in 1857 examined the 
 living animal of Millepora t and arrived at the conviction that 
 this genus was truly Hydrozoal (Amer. Journ. Sci. and Arts, 
 ser. 2, vol. xxvi. p. 140, 1858; Proc. Bost. Soc. Nat. Hist., 
 vol. vi. p. 373, 1859). This conclusion has since been fully 
 borne out by the researches of Mr Moseley, to be subse- 
 quently referred to ; but Professor Agassiz based upon his 
 discovery a further conclusion which certainly was not war- 
 ranted by the known facts namely, that the Hydrozoal nature 
 of Millepora sufficiently proved all the so-called " Tabulate 
 Corals " to be referable to the Hydrozoa. 
 
 Shortly after the publication by Professor Agassiz of his 
 unexpected discovery as to the Hydrozoal nature of Millepora, 
 Professor Verrill investigated the anatomy of the " Tabulate " 
 genus Pocillopora, Lam., and showed that the animal of this 
 Coral was a true Zoantharian, referable to the Aporosa, and 
 allied to the Oculinidce (Review of the Corals and Polypes of 
 the W. Coast of America, Trans. Conn. Acad., vol. i. pp. 2, 523, 
 1870; and Affinities of the Tabulate Corals, Proc. Amer. 
 Assoc. for Adv. of Science, p. 148, 1867). Professor Verrill 
 likewise, even at this date (Trans. Conn. Acad., loc. '/.), 
 powerfully supported the view that the Favositidce are not 
 only true Actinozoa, but that they are really referable to the 
 Zoantharia. In the year 1872 the same high authority pub- 
 lished an important memoir upon " The Affinities of the Palse- 
 
4 TABULATE CORALS. 
 
 ozoic Tabulate Corals with existing Species " (Amer. Journ. Sci. 
 and Arts, ser. 3, vol. iii. p. 187), in which he forcibly pointed out 
 that the discovery of the Hydrozoal nature of Millepora, Lam., 
 did not necessarily carry with it the reference of the whole 
 of the " Tabulata " to the Hydrozoa. On the contrary, he 
 affirms that, " as to the great majority of the ' Tabulata ' and 
 ' Rugosa,' there can no longer be any reasonable doubt " that 
 they are essentially animals of the same nature as " the exist- 
 ing Corals " (i.e., Zoantharia). The family of the Pocilloporidoe 
 is further established for the reception of Pocillopora and its 
 allies ; Columnaria is regarded as either a member of the 
 Astraida, or as referable to a closely allied family ; and the 
 Favositida are merged with the Poritidce, doubt being ex- 
 pressed as to whether the group can be retained as even a 
 sub-family. 
 
 In the year 1872, also, was published the admirable " Third 
 Report on the British Fossil Corals," by Professor Martin 
 Duncan, which was laid before the British Association for the 
 Advancement of Science in 1871, and published in the Report 
 of the Association. In this important memoir Professor 
 Duncan deals very largely with the structure and affinities of 
 the " Tabulate Corals " his wide knowledge of both living and 
 extinct Actinozoa rendering his views upon this subject par- 
 ticularly valuable and suggestive. Various of these views will 
 be noticed subsequently ; and it will be sufficient to state here 
 that he retains the " Tadulata" of Edwards and Haime as a 
 great division of the Zoantkaria, subdividing it as shown in the 
 following table : 
 
 Section TABULATA. 
 FAMILIES. 
 
 ( Milleporida, Coenenchyma cellular. 
 With coenenchyma, . . \ A . ., ^ , 
 
 3 \ Acropondce. Coenenchyma compact. 
 
 ( Favositida. Walls perforated. 
 
 Without coanenchyma, . . < Halysitidcz. Walls imperforate. 
 
 ( Alveolitida. Septa tridentate. 
 
CLASSIFICA TION. 
 
 GENERA. 
 
 MILLEPORID^:, 
 
 Milleporai 
 
 Heliolites, Heliopora, Polytremacis. 
 
 Propora, Plasmopora, Thecia. 
 
 HALYSITID^;, 
 
 Lyellia. 
 
 Thecostegites. 
 
 Axopora. 
 
 i Acropora, Seriatopora, Podllopora, 
 \ Dendropora, Rhabdopora. 
 / Favosites, Koninckia, Favositipora, 
 \ Michelinia, Rcemeria, Emmonsia. 
 \ Syringopora. 
 v Aulopora. 
 
 Halysites. 
 
 Stylophyllum. 
 
 Chonostegites. 
 
 Columnaria. 
 
 Beaumontia, 
 
 I Alveolites. 
 ALVEOLITID.E, , * , < ~ 
 
 ( Coemtes. 
 
 T j. ( Fistulipora. 
 
 Incertae sedis, . . . , <.. 
 
 { Fletcher ici. 
 
 ALCYONARIA. 
 CJicetetes, Moniiculipora, Dania, Stellipora^ Labechia. 
 
 Another very important memoir upon the " Tabulate Corals " 
 was published in 1873 ^Y Dr Gustav Lindstrom (Nagra an- 
 teckningar om Anthozoa Tabulata, Ofversigt af. Kongl. 
 Vetensk. Akad. Forhandl., 1873. Translated in the Ann. and 
 Mag. Nat. Hist., ser. 4, vol xviii. p. i, 1876). In this paper 
 the distinguished Scandinavian palaeontologist entirely aban- 
 dons the "Tabulata" of Edwards and Haime as a distinct 
 division of the Corals ; Labechia, E. and H., is placed amorig 
 the Hydrozoa, near to Hydractinia ; Monticulipora, D'Orb., 
 Fistulipora^ M'Coy, and some other forms, are regarded as 
 Polyzoa ; the Favositidce are placed in the Poritidtz, among the 
 Perforate Corals ; the Heliolitida are considered as forming a 
 
 1 In a note, Dr Duncan adds that though not satisfied (1872) that Millepora is a 
 Hydrozoon, he has great doubt about its Madreporarian affinities. He also points 
 to the extremely close relation between Heliolites and Heliopora, since so entirely 
 confirmed by Mr Moseley. 
 
TABULATE CORALS. 
 
 special group of uncertain zoological position ; Columnaria, 
 Goldf., is placed among the Cyathophyllidce, in the section of 
 the Rugosai Fletcheria, E. and H., and Michelinia, De Kon., 
 are referred to the Cystiphyllidce \ and Syringopora, Goldf., is 
 regarded as a Rugose Coral, allied to Lithostrotion or Diphy- 
 phyllum. I shall have occasion to notice many of the views 
 expressed by Dr Lindstrom in greater detail in dealing with 
 the families and genera of the Palaeozoic Tabulate Corals ; and 
 the general results of his investigations will be best understood 
 if I append here the following list, in which the various genera 
 of the " Tabulate" of Edwards and Haime are referred to what 
 Dr Lindstrom considers to be their true place in the zoological 
 system : 
 
 Name of Genus. 
 Millepora, 
 Heliopora, 
 Polytremads, 
 Heliolites, . 
 
 Fistulipora, 
 Plasmopora, 
 Propora, . 
 
 Lyellia, 
 Axopora, . 
 Batter sbyia, 
 Favosites ) 
 Emmonsia ) 
 Michelinia, 
 Alveolites, . 
 Ro&meria ) 
 Koninckia ) 
 Chcetetes \ 
 
 Monticulipora 
 Dania 
 Stellipora 
 Dekayia, . 
 Beaumontia, 
 Labechia, . 
 Sfylophyllum, 
 Halysites, . 
 
 Syringopora, 
 
 \ 
 
 To be removed to 
 
 Hydrozoa ? 
 
 Alcyonaria (Moseley). 
 
 Alcyonaria. 
 
 Heliolitidce (special family). 
 J Some species to Heliolites ; others 
 ( to the Polyzoa. 
 
 Heliolitida. 
 
 ( Heliolitida (probably inseparable 
 ( from Plasmopora). 
 
 Heliolitida. 
 
 Hydrozoa ? 
 
 Astrceida (Duncan). 
 ( Sub-family Favositina of the Pori- 
 l tida. 
 
 Cystiphyllida. 
 
 Partly Favositince, partly Polyzoa. 
 
 Favositince, 
 
 Polyzoa. 
 
 Polyzoa ? 
 
 Favositince. 
 
 Hydrozoa. 
 
 Hydrozoa ? 
 
 Heliolitidce. 
 
 ( Vicinity of Lithostrotion and Diphy- 
 1 phyllum. 
 
CLASSIFICATION. 7 
 
 Name of Genus. To be removed to 
 
 Thecostegites, . . . . . Heliolitidce. 
 
 Chonostegites, ..... Michelinia. 
 
 Fletcheria, ..... Cystiphyllidce. 
 
 Pocillopora, ..... Oculinidce (Verrill). 
 
 Cceniles, ...... Polyzoa ? 
 
 Seriatopora, ..... Oculinidce ? 
 
 Theria, ...... Heliolitidce ? 
 
 Columnaria, CyathophyttidfR, 
 
 In a paper published by M. G. Dollfus in 1875 (Comptes 
 Rend., t. Ixxx.), the Heliolitidce are regarded as unquestion- 
 ably the representatives of the recent Milleporidce a view 
 which Mr Moseley's researches have rendered altogether un- 
 tenable ; and the Pocilloporida are regarded, along with the 
 preceding, as Hydrozoa an opinion which the researches 
 of Professor Verrill have sufficiently disproved. Syringopora, 
 Halysites, Aulopora, and allied forms, are regarded as being 
 either Polyzoa allied to Hippothoa and Idmonea, or else Alcy- 
 onaria. The family of the Ck&tetidce is considered as hav- 
 ing a direct relationship with the Jurassic Polyzoa of the 
 genus Heteropora and the Cretaceous Radiopora. The Favo- 
 sitidce are regarded as most probably truly referable to the 
 Polyzoa, the " mural pores " being compared with the inter- 
 cellular pores of certain Escharce and Lepralice, and of some of 
 the Cyclostomatous Polyzoa (Fungella and Heteroporella). It 
 is clear, however, that the author's conception of the real struc- 
 ture of the Favositidce has been grounded upon very imperfect 
 materials. Lastly, Dendropora and *Trachypora which we 
 now know to be true members of the Favositidce are placed 
 among the Polyzoa, and are regarded as allied to Hornera. 
 
 In 1876 Mr Moseley published his exceedingly important 
 papers on the anatomy of the recent Millepora and Heliopora 
 (Notes on Two Species of Millepora, &c., Phil. Trans., 1876; 
 Structure of a Species of Millepora occurring at Tahiti, Ann. 
 and Mag. Nat. Hist., 1876; Structure and Relations of the 
 Alcyonarian Heliopora cserulea, Phil. Trans., 1876), which at 
 once threw a flood of light upon the subject of the structure 
 and affinities of the Palaeozoic "Tabulata" I shall have again 
 
8 TABULATE CORALS. 
 
 to refer to the investigations of Mr Moseley, as published in 
 the above-mentioned and later memoirs; and I shall merely say 
 here that their general result was to complete the disintegra- 
 tion of the "Tabulate" of Edwards and Haime, and to fairly 
 remove from the Zoantharia certain groups that had previously 
 been referred to this order of the Actinozoa. Thus, Millepora 
 and its allies, as formerly asserted by Agassiz, are definitely 
 proved to be true Hydrozoa, in which class they form, with the 
 Sty taster idee, the new order of the Hydrocorallince ; Heliolites 
 and its numerous allies, instead of being relations of Millepora, 
 are shown conclusively to be Actinozoa, but to be at the same 
 time referable to an unsuspected order of this class namely, to 
 the Alcyonaria; while various familiar types of the Palaeozoic 
 "Tabulata" are brought by these discoveries into more or less 
 probable relationships with either the Hydrozoa or the Alcyo- 
 naria; and light of the most important character is afforded as 
 to certain structural features in the Palaeozoic types, which 
 have hitherto proved obscure or inexplicable. 
 
 In the article " Corals " in the ' Encyclopaedia Britannica ' 
 (gth ed., vol. vi., 1877), I gave a short account of the then 
 existing state of our knowledge as to the structure and affin- 
 ities of the "Tabulate" Corals. In this article the researches 
 of Moseley are accepted ; the FavosUida are referred with 
 some doubt to the Perforate Zoantharia ; the Chcetetida are 
 separated from the Favositidce, and regarded as possibly Alcyo- 
 narian; the Syringoporida are shown to have affinities with 
 the Favositidcz; and the conclusion is arrived at, that if any 
 forms can be retained as a " Tabulate " order of the Zoantharia, 
 it is probably those represented by Syringopora and Halysites, 
 with their allies. 
 
 Lastly, Professor Zittel (Handbuch der Palaeontologie, Bd. 
 i. Lief, ii., 1879) accepts in the fullest sense the abolition of 
 the "Tabulata" of Milne-Edwards and Haime, and disposes 
 of the members of this group in different directions. Millepora 
 and its allies are placed, as is proper, in the Hydrozoa as also, 
 with less reason, is Labechia; the family of the Favositida is 
 
CLASSIFICATION. 9 
 
 referred, as is also probably correct, to the Perforate Corals, 
 and is regarded as a sub-family of the Poritidtz, Koninckia 
 being removed from it, and placed with Alveopora in another 
 sub-family (the Alveoporintz} of the same group ; Syringopora, 
 Aulopora, Haly sites, and their allies, are placed (without suffi- 
 cient reasons adduced) among the Alcyonaria, in the family of 
 the TubiporicUs ; and the Chcetetidce are entirely excluded from 
 the Actinozoa, being presumably regarded as truly belonging 
 to the Polyzoa. 
 
 The preceding historical sketch is necessarily extremely 
 brief and imperfect, the limited space at my disposal not allow- 
 ing it to be otherwise ; but it will be sufficient to show the 
 principal tendencies of the more recent researches of naturalists 
 and palaeontologists with regard to the old group of the " Tab- 
 ulate Corals." These researches, though still incomplete, are 
 so far advanced that the abandonment of the " Tabulata " as a 
 distinct group of the Zoantharia can hardly be avoided ; while 
 the removal elsewhere of some of the principal forms previously 
 included under this head is already a fact accomplished. It is, 
 indeed, now quite clear that the chief character relied upon by 
 Milne- Ed wards and Haime, in their definition of the "Tabzi- 
 lata" namely, the presence of "tabulae" is one of very 
 limited classificatory value. Thus, tabulae occur in Pocillo- 
 fiora, Cyathophora, Ccelastrcea, Claiisastrcea, and occasionally 
 in Lophohelia, among the Zoantharia Aporosa ; in Alveopora, 
 and the allied Favositipora, among the recent Zoantharia Per- 
 forata ; in Heliopora and its allies, in the Alcyonaria, as well 
 as occasionally in Tubipora ; in the great majority of the 
 Rugose Corals ; in Millepora and its allies among the Hydro- 
 soa; and lastly, in a few extinct types of the Polyzoa (e.g., 
 Radiopora and Heterodictyd). The mere fact of the occurrence 
 of tabulae in so many forms of such diverse zoological affinities, 
 is sufficient proof that these structures cannot be used in form- 
 ing a classification of the Corals; but it is at the same time con- 
 clusive that the "tabulae" of these different types, though undis- 
 tinguishable in appearance and performing identical functions, 
 
i o TAB ULA TE CORALS. 
 
 cannot .be precisely and in all cases homologous structures. 
 With regard to the " tabulse " in the true Actinozoa, Professor 
 Verrill concludes that " they are formed after each discharge of 
 ova : the vacuity thus produced, being useless, is cut off from 
 the visceral cavity above it by the formation of a septum. 
 Therefore, if the eggs be discharged from all the radiating 
 chambers simultaneously, or if from any other cause the polyp 
 abandons all the chambers simultaneously, it is obvious that a 
 complete septum or transverse plate will be formed across the 
 entire tube ; but if the' eggs be discharged at different times 
 from the ovaries occupying the various radiating chambers, the 
 septa formed below them in the different chambers will not be 
 coincident, or exactly at the same level in all. It would seem, 
 therefore, that the existence or non-existence of complete trans- 
 verse plates is simply a matter of periodicity in the discharge 
 of ova" (Amer. Journ. Sci. and Arts, sen 3, vol. iii. p. 187). 
 Dr Lindstrom has further adduced a considerable body of evi- 
 dence in support of the view that the " tabulse " are only a 
 modification of the endothecal " dissepiments " (Ann. and Mag. 
 Nat. Hist., sen 4, vol. xviii. pp. 2, 3). That this is the case in 
 certain instances (such as Ccelastr&a, Verrill) seems quite un- 
 questionable; and it is indeed easy to see how the simultaneous 
 production of dissepiments in all the intermesenteric chambers, 
 at one level, would give rise to a structure entirely undistin- 
 guishable from a " tabula." There are, however, some consid- 
 erations which should not be lost sight of, before it is concluded 
 that the " tabulse " of the tabulate Actinozoa are merely modified 
 interseptal dissepiments. Thus it is to be remembered that in 
 the Rugose Corals there is generally a simultaneous develop- 
 ment of both these structures, and that the " tabulse " are best 
 developed in the axial region of the visceral chamber, into 
 which the septa either only penetrate slightly (Diphyphyllum) 
 or do not enter at all (Amplexus), and in which, therefore, 
 " dissepiments " are either scanty or totally absent. Again, in 
 various members of the Favositidcz, the septa are obsolete ; and 
 there are therefore necessarily no " interseptal dissepiments," 
 
, CLASSIFICATION. n 
 
 in the ordinary acceptation of this term, though the " tabulae " 
 are well developed. Moreover, it begs the question at issue to 
 speak of the vesicular plates of the Cystiphyllidce as being of the 
 nature of "crowded and regular horizontal dissepiments" which 
 simulate " tabulae ; " since it is just as likely that they are 
 crowded and anastomosing tabul<z, which simulate " dissepi- 
 ments." In the entire family of the Chcetetidce (assuming these 
 in the meanwhile to be Actinozoa} the "tabulae" are well de- 
 veloped ; but there are no septa, and therefore no " dissepi- 
 ments," unless the latter are represented by the tabulae. 
 Lastly, in the Helioporida it has been shown by Mr Moseley 
 that the so-called septa are not homologous with the septa of 
 the Zoanthariai and it is therefore improbable that the well- 
 developed tabulae of the former should be homologous with 
 the " interseptal dissepiments " of the latter. 
 
 Whatever may be, however, the nature of the "tabulae" 
 in the various groups of Actinoza which possess them, and 
 whether or not they are always periodic partitions formed 
 after the discharge of the ova (Verrill), or mere modifications 
 of the interseptal dissepiments (Lindstrom), it is clear that 
 they cannot be homologous with the apparently identical struc- 
 tures in certain other sections of the old group of the " Tabu- 
 lata." Mr Moseley, for example, has shown that the Milleporce 
 are truly Hydrozoa, and that their ova are therefore not pro- 
 duced within the visceral chambers. It is clear, therefore, that 
 in these forms the " tabulee " cannot be modified " dissepi- 
 ments," and still less partitions formed subsequent to the 
 extrusion of the ova. It must also be admitted that any 
 transverse plates which may be found to intersect the cells of 
 undoubted Polyzoa (such as Heterodictya, Nich.) must be of a 
 fundamentally different nature to the " tabulae " of either the 
 " tabulate " Actinozoa or of the Millepores, though they may 
 not be distinguishable from these in appearance. 1 
 
 1 It follows from the above that if the name of " tabulae " be retained for the 
 transverse partitions found in the visceral chamber of certain Actinozoa, it can 
 hardly be said in any strict scientific sense that "tabulae" are present in certain 
 Hydrozoa (MilleporidfE) and certain Polyzoa (Heterodictya). The proper course, 
 
12 TABULATE CORALS. 
 
 With the abandonment of the "tabulae" as structures of 
 classificatory significance, the "T&bulaia* of Milne -Edwards 
 and Haime must necessarily be broken up and undergo 
 redistribution. It remains, however, for consideration, what 
 groups are really included under the old name of " Zoantkaria, 
 Tabulate" and whether or not this name may still be retained, 
 in a restricted sense, for any of the forms originally placed 
 under it. By the investigations of Agassiz, Verrill, Lindstrom, 
 Duncan, Moseley, Rominger, and others, we have been made 
 acquainted with the true structure and relationships of several 
 of the groups which constituted the old division of the Tabu- 
 lata, and my own researches upon the varied and numerous 
 Palaeozoic types have enabled me to throw some light upon 
 the nature and position of some of the others. Our present 
 knowledge is admittedly imperfect ; but it would appear that 
 the division of the Zoantharia Tabulata, as until very recently 
 understood, comprises about twelve distinct groups of animals. 
 Of these groups, the first two are not known (with any cer- 
 tainty, at any rate) to have had any Palaeozoic representatives, 
 and I shall therefore say here what appears to me to be 
 necessary concerning them ; while I shall merely summarise 
 the characters of the remaining groups, all of which I shall 
 have to treat of hereafter at greater length : 
 
 I. MILLEPORID^:. The corallum in this group is usually 
 foliaceous, lobate, or sub-massive, and it is composed of an 
 extremely porous coenenchyma, traversed in every direction 
 by tubular canals, which freely communicate with one another, 
 and which also open into the visceral chambers of the polypites 
 themselves. The surface (fig. i, c) exhibits two sets of aper- 
 tures, one large and the other small, the larger ones being 
 much the fewest. The large openings (the true "calices") 
 are the mouths of tubes which are crossed by well-developed 
 transverse partitions or ''tabulae" (fig. i, B), the living animal 
 inhabiting only the outermost of the chambers thus formed. 
 
 in fact, would be to give another name to the structures in the two latter groups 
 which simulate the "tabulae" of the first group. 
 
CLASSIFICATION. 13 
 
 The smaller tubes are similarly "tabulate." No " septa" are 
 present. The living animal of Millepora was first examined 
 by Professor Louis Agassiz, as the result of which he pro- 
 nounced it to be a Hydrozoon, allied to Hy dr actinia ; but its 
 anatomy was first thoroughly studied and worked out by Mr 
 Moseley (Phil. Trans., vol. clxvii. p. 117, 1877), who showed 
 that it was in reality the type of a special group of Hydrozoa, 
 
 Fig. I A, Portion of a mass of Millepora alcicomis, of the natural size; B, Portion of the 
 
 same, cut open vertically to show the larger tabulate tubes (/, /), and the spongy cceno- 
 sarcal skeleton (c, c), enlarged; c, Small portion of the surface, enlarged to show the 
 larger and smaller openings (f, c 1 } inhabited by the different zooids, and the reticulated 
 calcareous tissue of the skeleton ; D, Part of a polypite, enlarged, showing two whorls of 
 knobbed tentacles. (A, B, and c are after Milne-Edwards and Haime ; D is after 
 Martin Duncan and Major-General Nelson.) 
 
 to which he gave the name of HydrocoralliiuB. According to 
 the observations of this naturalist, the colony of Millepora con- 
 sists of two kinds of zooids, differing from one another in size, 
 in structure, and in function. The larger zooids the "gastro- 
 zooids " of Mr Moseley occupy the larger tubes of the coral- 
 lum, and have the form of short polypites, each of which pos- 
 sesses four tentacles, surrounding a central mouth, which opens 
 into the gastric cavity of the zooid (fig. 2, a). Mixed with the 
 " gastrozooids," or surrounding these in definite systems, are 
 more numerous long and slender zooids the " dactylozooids " 
 of Mr Moseley which carry numerous clavate tentacles (fig. 2, 
 
TABULATE CORALS. 
 
 b], and are destitute of any mouth. The " dactylozooids " per- 
 form the functions of prehension for the colony, and supply 
 food to the " gastrozooids," by which the work of digestion 
 
 Fig. 2. Enlarged view of a portion of the surface of a living colony of Millepora nodosa, 
 showing the expanded zooids of a single system, a, Central "gastrozooid ;" b, One of 
 the mouthless "dactylozooids." (After Moseley.) 
 
 and assimilation is carried on. The nutritive fluid thus elabor- 
 ated is distributed over the entire colony by means of branched 
 ccenosarcal canals, which communicate with the body-cavities 
 of the zooids, and ramify in every direction through the spongy 
 ccenenchyma. 
 
 Of the genera associated by Edwards and Haime with 
 Millepora, Heliopora and its Palaeozoic and Secondary allies 
 are now known to be referable to the Alcyonaria; Fistnlipora, 
 M'Coy, belongs undoubtedly to the family of the Monticnlipor- 
 idce ; and the Tertiary Axopora, with its fasciculate columella, 
 is of uncertain affinities. Millepora itself is only known as a 
 Tertiary fossil, and as living ; but the Cretaceous genus Poro- 
 sphcera, Steinm., appears to be closely related to Millepora, 
 and therefore also to belong to the Hydrocorallince. 
 
 II. POCILLOPORID.E. The corallum (fig. 3) of Pocillopora, 
 the type of this group, is dendroid or foliaceous, composed of 
 numerous tubular corallites, which are surrounded by an imper- 
 
CLASSIFICA TION. 
 
 forate compact coenenchyma ; are provided with six, twelve, or 
 twenty-four septa, sometimes obsolete ; and are intersected by 
 complete transverse tabulae. A rudimentary columella is pres- 
 ent. The animal of Pocillopora has been examined by Profes- 
 sor Verrill (loc. jam cit.), who describes the polypes as being 
 " exsert in expansion, with a regular circle of twelve nearly 
 equal, stout, tapering tentacles surrounding the circular disc ; 
 and twelve internal, radiating, fleshy lamellae show through 
 the disc. Thus they closely resemble the polypes of Stylo- 
 phora, Forties, and Madrepora, which are among the most 
 typical of the true polypes. The existence of stellate cells 
 
 F'g- 3- A - Portion of the corallum of Pocillopora aspzra, var. lata, Verrill, of the natural 
 size ; B, Part of the surface of same enlarged ; c, Section of the corallites of the same, 
 showing the columella, enlarged ; D, Vertical section of the same, enlarged, showing 
 tabulae. (After Dana.) Recent. 
 
 with six or even twelve well-developed radiating septa in 
 several species of Pocillopora (e.g., P. elongata, Dana, P. 
 plicata, D., P. stellata, V.), should be sufficient evidence that 
 such Corals have no Acalephian affinities whatever, even 
 without the conclusive evidence derived from a study of the 
 living polypes " (Amer. Journ. Sci. and Arts, ser. 3, vol. iii. 
 p. 191). 
 
 It cannot be doubted, then, that Pocillopora, Lam., is a true 
 Aporose Zoantharian, most nearly allied to the Oculinidce; but 
 there is some doubt as to the forms which should be associated 
 with it, since in none of the allied types are we acquainted with 
 the structure of the animal itself. The corallum of Seriatopora, 
 Lam., however, so closely resembles that of Pocillopora in its 
 
1 6 TABULATE CORALS. 
 
 general structure, that this genus must almost certainly be 
 placed alongside of the latter, even if not actually united with 
 it, as proposed by Professor Martin Duncan. We may thus 
 abolish the family Seriatoporidce, of which Seriatopora was the 
 type. The genus Pocillopora is Recent and Kainozoic, and it 
 is questionable if any fossil forms of Seriatopora are known. 
 It may at any rate be taken as certain that the alleged forms 
 of Seriatopora from the Palaeozoic deposits will be proved to 
 have different affinities. The Palaeozoic genera Trachypora, 
 Dewdropora, and Rhabdopora, usually associated with Seria- 
 topora, Lam., are, again, truly Perforate Corals destitute of a 
 ccenenchyma, and belonging to the Favositida. 
 
 III. FAVOSITID.E, The corallum in this family is of very 
 variable form, but is composed of polygonal or subcylindrical 
 corallites, which are usually in close contact throughout their 
 entire extent, and are furnished with well -developed walls. 
 The walls are, however, perforated by a greater or smaller 
 number of rounded apertures the " mural pores " (fig. 4, B) 
 by which the visceral chambers of contiguous polypes are 
 placed in direct communication. There is no true ccenen- 
 chyma ; and the condition of the septa is extremely variable, 
 
 Fig. 4. A, Portion of the corallum of Favosites favosa, of the natural size ; B, Portion of four 
 corallites of Favosites Gothlandica, enlarged, showing the tabulae and the "mural pores." 
 
 these structures being sometimes obsolete (some forms of 
 Trachypora, &c.), sometimes in the form of marginal lamellae 
 or ridges (Nyctopora, Nich.), and most commonly represented 
 by vertically-disposed rows of spinules (most species of Favo- 
 
CLASSIFICATION. 17 
 
 sites). The tabulae are usually well developed and complete, 
 but they are sometimes imperfect (Favosites hemispherica, Yand. 
 and Shum.) 
 
 After an extended study of the minute structure of the 
 Fctvositida, I cannot doubt but that Professor Verrill and 
 Dr Lindstrom are right in referring all the Corals usually 
 included under this head to the Zoantharia Perforata. I 
 also fully recognise the many points of resemblance between 
 the Favositidcz and the Poritidee^ but I am not prepared to 
 follow the above-mentioned distinguished authorities in regard- 
 ing the present group as a mere sub-family of the Poritidce. 
 On the contrary, I think that the group Favositidce, as here 
 understood, embraces a large number of types (mostly Palaeo- 
 zoic), all of which are more or less allied to the Poritidce, and 
 some of which may perhaps be capable of final removal to the 
 latter family, but which really represent a series of separate 
 though allied groups. The reasons for this opinion will be 
 stated at greater length hereafter. I need only say here 
 that there is not the slightest ground, in my opinion, for 
 regarding the Favositida as anything but true Actinozoa, or 
 for removing them from the order of the Zoantharia. They 
 are not connected with the Heliolitidce by any links sufficiently 
 close to lead us to suppose that they are Alcyonaria ; and the 
 hypothesis of Dollfus (Comptes Rend., t. Ixxx., 1875), that 
 they are truly referable to the Polyzoa, hardly requires serious 
 refutation. 
 
 IV. CoLUMNARiADyE. Under this head I provisionally place 
 a few Palaeozoic Corals, of which the only typical and un- 
 doubted examples known to me are C. alveolata, Goldf. 
 (Favistella stellata. Hall), and C. calicina, Nich. Both of these 
 have coralla composed of polygonal or subcylindrical corallites, 
 with well-developed compact walls, not penetrated by " mural 
 pores." The septa are lamellar, in two series, those of the 
 longer set extending nearly or quite to the axis of the visceral 
 chamber. There is no columella ; and though the corallites 
 may be to some extent disjunct, there is nothing of the nature 
 
 B 
 
1 8 TABULATE CORALS. 
 
 of a ccenenchyma. The tabulae are always remarkably well 
 developed. Columnaria f Halli, mihi (the C. alveolata of 
 American palaeontologists), may be temporarily included in this 
 group, though there are grounds for believing that the walls of 
 its corallites are perforated, and its septa are of the marginal 
 character of Nyctopora Billingsii, Nich., which has unquestion- 
 able " mural pores," and must therefore be placed among the 
 Favositidce. We may also provisionally place in or near the 
 Columnariadce the singular genus Lyopora, Nich. and Eth. jun., 
 though it differs from the typical Columnaricz in the great thick- 
 ness of its walls and the very rudimentary condition of its septa. 
 
 As to the precise position of the typical Columnarice in the 
 zoological series, it does not seem at present possible to speak 
 with anything like certainty. The typical forms of the group 
 exhibit certain curiously Rugose features in the disposition of 
 the septa, and may really form a special type of the Rugosa. 
 On the other hand, they present some conspicuous points of 
 resemblance to the Astfceida among the Zoantharia Aporosa. 
 
 V. SYRINGOPORID^E. In this group the corallum is fascicu- 
 late (figs. 5-7), commencing in the form of a creeping stolon- 
 iferous network, which sends up vertical and more or less 
 cylindrical corallites, which are never in absolute contact, ex- 
 
 Fig. 5. Syritigopora reti- 
 formis. Silurian. 
 
 Fig. 6. Syringopora ver- 
 ticillata. Silurian. 
 
 Fig. 7. Syringopora Dal- 
 mani. Silurian. 
 
 cept, perhaps, at quite limited intervals, and are enclosed by 
 strong compact walls. The visceral chambers of contiguous 
 corallites are placed in direct communication by means of 
 hollow connecting-processes. Septa, of a spiniform and rudi- 
 mentary character, are present as a rule. The tabulae are 
 well developed, more or less funnel-shaped, and sometimes 
 
 
CLASSIFICATION. i 9 
 
 giving rise to an axial tube in the median line of the visceral 
 cavity. There is no columella. The entire group, so far as 
 known, is confined to the Palaeozoic period. 
 
 It is probably impossible, with our present knowledge, to 
 assign an absolutely final place to the Syringoporida in the 
 zoological series. I am quite unable to agree with the opinion 
 held by Dana, Haeckel, and Zittel, that the true place of Sy- 
 ringopora and its allies is in the immediate neighbourhood of 
 the recent Tubipora ; as I can see nothing but resemblances of 
 an analogical nature between these two genera. Nor can I 
 accept the view advocated by Lindstrom (Ann. and Mag. Nat. 
 Hist, sen 4, vol. xviii. p. 14), that Syringopora is truly a Rugose 
 Coral, with relationships to Lithostrotion and Diphyphyllum. 
 Nor, again, am I at present inclined to admit that the Corals 
 usually grouped together under the generic titles of Aidopora 
 and Cladochonus ( = Pyrgia, E. and H.) are really nothing more 
 than young forms of Syringopora ; though I fully grant that the 
 immature stages of the latter may be undistinguishable from 
 the fully-grown condition of the former. On the contcary, I 
 am upon the whole disposed to think that the real relation- 
 ships of the Syringoporidce are with the Favositida, and that 
 they should therefore find a place, though a special one, in 
 the series of the Zoantharia Perforata. I regard the con- 
 necting-tubes (when present, as apparently they are not inva- 
 riably) as being the homologues of the " mural pores " of 
 the Favositidce i and the curious genus Syringolites, Hinde, 
 which I shall subsequently describe, affords an unquestion- 
 able link between these two groups. This singular type, in 
 fact, possesses the infundibuliform tabulae, and even the axial 
 tube, of certain Syringoporidce, along with the polygonal, 
 contiguous corallites, and the serially-disposed " mural pores," 
 of the Favositidce. The septa of Syringopora are furthermore 
 of the spiniform and rudimentary character so distinctive of 
 the Favositidai and there is no solid reason, so far as I am 
 aware, for regarding them as being really of the nature of the 
 "pseudo-septa" of certain Alcyonarians. 
 
20 
 
 TABULATE CORALS. 
 
 VI. AULOPORID^:. This group is at present in such a totally 
 chaotic condition, that it is almost impossible to come to any 
 positive conclusion as to its true relationships or as to the 
 forms which it may contain. The genera Aulopora and 
 Cladochonus (^Pyrgia) were, as is well known, raised by 
 Milne-Edwards and Haime to the rank-of a distinct sub-order 
 of the Zoantharia the Z. Tubulosa (Pol. Foss. des Terr. Pal., 
 310, 1851) having been previously placed by them in the Al- 
 cyonaria. The alleged characters of the family are, that the 
 pyriform corallites are destitute of "tabulae/ 5 and possess nothing 
 but vertical striae representing the septa, while there are no 
 mural pores or connecting-tubes by which the visceral chambers 
 of contiguous corallites are placed in direct communication. 
 Taking Aulopora itself (fig. 8, A) as the type of this group, the 
 corallum is creeping, and attached by the whole of its lower 
 
 Fig. 8. A, Portion of the corallum of Aulopora tubaformis, Goldf., from the Devonian of 
 the Eifel, of the natural size ; B, Two corallites of the same enlarged, showing septal 
 striae ; c, Cladochonus (Pyrgia) Michelini, E. and H. , Carboniferous, of the natural size ; 
 D, The same slightly enlarged, showing the interior of the calice. 
 
 surface to some foreign body. The basal stolons divide and 
 send up the tubular or trumpet-shaped corallites, the terminal 
 portions of which are free and erect ; but in no case is the pro- 
 cess carried to the extent of producing a fasciculate corallum. 
 The tubes are for the most part not in contact with one 
 
CLASSIFICATION. 21 
 
 another, and there is no evidence of the existence of " mural 
 pores" in such parts of their extent as they may be actually 
 contiguous. The septa are reduced to marginal striae ; and 
 horizontal complete tabulae are known to be present in certain 
 forms, though they have not yet been detected in others. 
 
 It is well known that the basal and young portion of the 
 corallum of Syringopora is in the form of a creeping stolonifer- 
 ous expansion, almost undistinguishable from the adult colony 
 of Aulopora in appearance. This fact has led high authorities to 
 the belief that the genus Aulopora has no existence, and that 
 it is merely based upon young colonies of Syringopora. This 
 view of the subject appears to me to be untenable with our 
 present knowledge and I think Aulopora to be really quite 
 distinct from Syringopora. I base this belief upon the fact 
 that the corallum in Aulopora is always prostrate and parasitic, 
 never becoming erect ; that there are no traces of hollow con- 
 necting-processes between the corallites ; and that the tabulae 
 (when known to be present) are horizontal, or if infundibuli- 
 form, do not give rise to an axial tube. There is also the 
 strong geological argument for the distinctness of the genus, 
 that formations abounding in Syringopora (such as the Car- 
 boniferous Limestone series of Britain) are almost (in most 
 places wholly) destitute of Aulopora; whereas the latter are 
 extremely plentiful in deposits (such as the Devonian Limestone 
 of Gerolstein in the Eifel) in which Syringopora are almost 
 or quite unknown. The genus Cladochonus, M'Coy (which 
 is apparently the same as Pyrgia, Edw. and H.), seems to 
 comprise forms of different affinities. Some of the species 
 seem to be tabulate, with horizontal tabulae, and may perhaps 
 be identical with Aiilopora proper. The Cladochonus crassus 
 of M'Coy, however, has an entirely peculiar internal structure, 
 which must remove it altogether from the Auloporida. 
 
 VII. HALYSITID^E. In this group, typified by the common 
 " Chain-corals," the corallum is composed of long cylindrical 
 corallites, united with one another successively on opposite 
 sides of the tubes, so as to give rise to flattened laminar expan- 
 
22 
 
 TABULATE CORALS. 
 
 sions, each composed of a single layer of corallites, these layers 
 frequently anastomosing and uniting with one another (fig. 9, 
 a and 6). Between each pair of corallites, and forming the 
 medium of junction between their opposed faces, is generally 
 a much smaller tabulate tube, with close-set tabulae (fig. 9, d). 
 
 Fig- 9- a t Halysites catenularia, Linn., small variety, of the natural size ; b, Large variety of 
 the same, of the natural size ; c, Halysites agglomerata, Hall ; d, Section of two corallites 
 of the same, enlarged. Niagara Limestone. 
 
 The larger tubes are crossed by complete, generally horizontal 
 tabulae, which are much farther apart than those in the smaller 
 intermediate tubes. The septa are minute and spiniform, and 
 the walls of the corallites are entirely compact and imperforate, 
 nor are there any connecting - tubes by which the visceral 
 chambers of different polypes are placed in communication. 
 
 By Milne-Edwards and Haime the family of the Halysitida 
 was made to include the Syringopora ; and that there are cer- 
 tain alliances between these groups cannot be denied. I con- 
 sider, however, that the fact that the polypes of Halysites are 
 destitute of any communication with their neighbours is suffi- 
 cient of itself to warrant the separation of the genus from the 
 Syringoporida. The latter, as has been seen, may perhaps 
 be regarded as aberrant Perforate Corals ; but it is difficult to 
 speak at all positively as to the systematic position and affin- 
 
CLASSIFICATION. 23 
 
 ities of the Halysitidce, as here restricted. Upon the whole, 
 I am inclined to think that Halysites will find its nearest ally 
 in the Helioporidce, which it resembles in one important fact 
 namely, in the general possession of two sets of tubes (indi- 
 cating the existence of two sets of zooids). Moreover, the tubes 
 of the one series are of large size, with remote tabulae ; while 
 those of the other set are small, and have close-set or vesicular 
 tabulae. If this conjecture be correct, then Halysites must be 
 removed from the Zoantharia to the Alcyonaria (a course 
 which several authorities have already followed) ; but it will in 
 any case form the type of a distinct group. 
 
 Fig. 10. A, Fragment of the corallum of Tetradium minus, Safford, from the Lower Silu- 
 rian of North America, of the natural size ; B, Transverse section of the same, enlarged 
 ten times, showing the petaloid form of the tubes and the short septa ; c, Vertical section 
 of the same similarly enlarged, showing the tabulse. 
 
 VIII. TETRADIID^;. This group includes only the singular 
 Silurian genus Tetradium, Dana, in which the corallum is 
 massive, and is composed of polygonal or subcylindrical coral- 
 lites of great length, and closely contiguous. No "mural 
 pores" or other openings in the walls are present. The 
 tabulae are numerous and complete, and the septa are few in 
 number, typically four, short, and seeming as if formed by 
 inflections of the wall (fig. 10). Most of the examples of 
 Tetradium have the form and general appearance of Ch&tetes 
 radians, Fischer, and its allies; but Safford (Amer. Journ. 
 Sci. and Arts, ser. 2, vol. xxii. p. 236, 1856) records the 
 occurrence of specimens in which the corallites are united in 
 
24 TABULATE CORALS. 
 
 single intersecting series, as in Halysites, and Billings has 
 figured similar forms (Geol. of Canada, fig. 71, 6). Professor 
 Safford regarded the genus as referable to the Rugosa, on 
 account of the quadripartite character of the septa ; but the 
 relations of the genus to Haly sites were pointed out by Mr 
 R. Etheridge, jun., and myself (Ann. Nat. Hist, ser. 4, 
 vol. xx. p. 163). It approaches Haly sites in its long tubular 
 corallites, its imperforate walls, and occasionally in its mode 
 of growth ; but its peculiar septa, and the want of smaller tubes 
 among the larger ones, would show it to be the type of a 
 special group. Its septa are much more like those of Heliolites 
 than of Halysites, looking as if they were formed by inflections 
 of the wall inwards along its whole length ; and I think that the 
 genus will probably have to be referred to the Alcyonaria^ 
 though I know of no group of this order to which it could be 
 definitely referred. 
 
 IX. THECID.E. This group comprises only the singular 
 Silurian genus Tkecia, Edw. and H., the corallum of which 
 forms laminar expansions, covered below by an epitheca, and 
 having the calices placed upon the upper Surface. The 
 tubular corallites cannot be said to be bounded by distinct 
 proper walls ; but they are embedded in and surrounded by 
 a dense tissue composed of minute polygonal vertical tubuli, 
 which normally open on the surface by very small and irreg- 
 ular, often stelliform, apertures. A few blunt septal ridges 
 (five to ten in number) project into the visceral chambers of 
 the polypes, which are crossed by irregular but well-developed 
 tabulae, and likewise often communicate with neighbouring 
 tubes by means of canals passing horizontally through the 
 intervening tissue. The smaller tubuli, which separate the 
 larger corallites, do not appear to be distinctly tabulate. 
 
 The structure of this genus is so extraordinary that it must 
 clearly form the type of a special group, as it was made to do 
 by Milne- Ed wards and Haime. Nor need we wonder that its 
 anatomy has been so little comprehended, seeing that its real 
 structure can only be made out by means of microscopic sec- 
 
CLASSIF1 CA TION. 2 5 
 
 tions, and that, owing to the great density of its tissues, even 
 the finest of these leave certain important points obscure. I 
 shall have to deal with the genus at greater length at a later 
 period, and will only say here that it seems to form in some 
 respects a link between the Perforate Corals and the Alcyo- 
 narian family of the Helioporidce. It resembles the former in 
 the fact that the visceral chambers of contiguous corallites are 
 placed in communication by a well-developed system of hori- 
 zontal canals ; and, on the other hand, it approaches the latter 
 in the fact that the ordinary polypes are surrounded by what has 
 been generally regarded as a tubular " ccenenchyma," though 
 not truly of this nature. The so-called " ccenenchymal tubuli " 
 judging from the analogy of the recent Heliopora are really 
 tenanted by special zooids, and are therefore not truly ccenen- 
 chymal. In the possession, then, of a series of large polypes 
 surrounded by a much more numerous series of smaller special- 
 ised polypes, Thecia agrees with Heliopora and Heliolitcsi and 
 the genus is therefore probably Alcyonarian. It differs, how- 
 ever, from the above in the fact that the corallites do not possess 
 distinct walls ; the septa of the large tubes are broad and tooth- 
 like, and the interstitial tubuli are apparently destitute of 
 tabulae, irregular, and opening on the surface by very minute, 
 often stellate, apertures ; while the larger polypes are directly 
 connected by lateral canals. These peculiarities fully entitle it 
 to be regarded as the type of a special family. 
 
 X. HELIOPORID^;. This family has been founded by Mr 
 Moseley (Phil. Trans., vol. clxvi. p. 92, 1876) for the recep- 
 tion of the extraordinary recent Heliopora, and the long ex- 
 tinct Heliolites, Plasmopora, and allied forms. The corallum 
 in this family (fig. n) is composed of two sets of corallites, a 
 larger and smaller the latter hitherto, but wrongly, termed 
 " ccenenchymal tubuli." The larger tubes are furnished with 
 delicate septa (generally twelve in number), and are traversed 
 by remote complete tabulae (fig. n, c). The smaller tubes 
 everywhere surround the larger ones, have no septa, and are 
 crossed by more numerous tabulae. Heliolites and most of its 
 
26 
 
 TABULATE CORALS. 
 
 allies are Palaeozoic, Polytremacis is Secondary, while Helio- 
 pora commences in the Chalk and still survives. The true 
 affinities of this singular group of Corals were quite unknown 
 
 Fig. II. A, Small colony of Helioliles megastoma, of the natural size ; B, Small portion of the 
 surface of the same, magnified, showing the calices of the large and small tubes (a and b) ; 
 C, Vertical section of the same, enlarged, showing the large tabulate corallites (a) and 
 the smaller tabulate tubes of the so-called crenenchyma (b). 
 
 till Mr Moseley examined the living animal of Heliopora 
 c&rulea, from which he was enabled to prove conclusively 
 that Heliopora and its ancient relatives are truly Alcyonaria, 
 and not Zoantharia. The corallum in Heliopora ccerulea is 
 in all essential features entirely similar to that of Heliolites. 
 As in the latter genus, the corallites are tubular, with well- 
 developed tabulae, and having their walls folded in such a 
 manner as to give rise to a variable number (generally twelve) 
 of septal laminae. The ccenenchyma, so called, is composed 
 of slender tubes, of smaller size than the true corallites, packed 
 closely side by side, crossed, like the corallites, by regular 
 transverse tabulae, but destitute of septa. The soft parts 
 occupy only the parts of the corallum above the uppermost 
 tabulae, and therefore only a surface - layer of the colony is 
 actually alive. The polypes are completely retractile, with 
 eight pinnately-fringed tentacles and eight mesenteries. The 
 mesenteries, however, have no correspondence with the septa, 
 
CLASSIFICATION. 27 
 
 which are twelve in number as a rule. The septa are thus 
 seen to be pseudo-septa, and they cannot be regarded as being 
 homologous with the septa of the Zoantharia sclerodermata. 
 The so-called ccenenchymal tubes are occupied by sacs lined 
 by the endoderm, which are closed externally, but communi- 
 cate freely with the body-cavities of the polypes by means 
 of transverse canals ; and Mr Moseley suggests, with great 
 probability, that these are really of the nature of rudimentary 
 sexless polypes. 
 
 XI. CHLETETHLE. This group is almost certainly made up 
 of very heterogeneous materials, and will undergo disintegra- 
 tion when subjected to a sufficiently searching investigation. 
 As it is even, the lines along which this disintegration will take 
 place can be to some extent discerned. Taking the miscella- 
 neous assemblage of forms at present included in it, no other 
 general definition of the group seems possible than that it com- 
 prises very variably -formed corals, composed of contiguous, 
 thin-walled, mostly prismatic corallites, which have imperfor- 
 ate walls, are intersected by well-developed tabulse, and are 
 destitute of septal laminae or spines. 
 
 Taking the typical members of the Ch&t$tid& viz., Chcetetes 
 radians, Fischer, and its few immediate allies we find that we 
 have to deal with corals in most essential respects similar to 
 those of the typical Favositidce, except that " mural pores " or 
 other openings in the walls are wanting, while there are (in 
 reality) no traces of septa, and the walls of the corallites are 
 completely amalgamated. These differences are of course such 
 as to show that the place of Chcetetes in the system must be far 
 removed from that oi.Favosites. I am nevertheless satisfied 
 that Chcetetes radians, Fischer, and the forms immediately 
 related to it, are genuine Actinozoa, though I am not able to 
 assign to them any certain place in this class. So far as one 
 can judge, they seem to have more affinities with the Alcyo- 
 naria than with any other group. 
 
 The position of the numerous forms referred to Monticuli- 
 pora, Fistulipora, and other allied types (which I shall provi- 
 
28 
 
 TABULATE CORALS. 
 
 sionally regard as a separate group, the Monticuliporidce) is, 
 again, uncertain. Strong evidence has been brought forward to 
 prove that all these forms are Polyzoa ; but it certainly cannot 
 be said that this conjecture has yet been sufficiently established. 
 I shall consider this subject again at greater length ; and I need 
 only add here, that though some of these forms may possibly 
 turn out to be Polyzoa, I am strongly disposed to think that the 
 majority will prove to be true Actinozoa. This seems to be 
 indicated, as a general conclusion, by their close resemblance in 
 many cases to types of an undoubted Ccelenterate nature ; by 
 the fact that their coralla are usually or always composed of 
 two sets of corallites, pointing to a heteromorphic condition of 
 their zooids, such as is highly characteristic of many of the 
 Caslenterata, and especially of certain of the Alcyonaria; and 
 lastly, by the fact that no forms possessing their characteristic 
 features in conjunction have as yet been pointed out as existing 
 among either recent or fossil Polyzoa. 
 
 XII. LABECHID^:. This extraordinary group comprises 
 only the anomalous genus Labechia, E. and H., at present 
 only known as a Silurian fossil. The skeleton in this genus 
 forms a laminar or expanded mass (fig. 12), the under sur- 
 
 Fig. 12. A, A small specimen of Labechia conferta, E. and H., from the Upper Silurian of 
 Gotland, of the natural size. B, Portion of the upper surface of the same, enlarged, c, 
 Part of a vertical section of the same, enlarged : a, the calcareous columns, represented 
 as opaque ; b, the lenticular vesicles filled with calcite. 
 
 face of which is covered by an epitheca, while the upper ex- 
 panse shows an apparently imperforate surface, rising above 
 
CLASSIFICATION. 29 
 
 which are close -set tubercles. Microscopic sections show 
 that these tubercles are the projecting summits of a series 
 of short, calcareous, and entirely solid, though seemingly 
 primitively tubular, columns, separated from one another by a 
 loose vesicular tissue, formed by the anastomosis of curved 
 calcareous lamellae. Dr Lindstrom has strongly supported the 
 view that Labechia originally placed by Edwards and Haime 
 among the Chcetetidce is truly a Hydrozoon, allied to Hydrac- 
 tinia. The peculiarities in its structure are, however, so 
 numerous, and the apparent total absence of any superficial 
 openings of any kind is so puzzling, that I do not at present 
 see how it can be placed among either the Hydrozoa or the 
 Actinozoa ; nor am I able to give any definite opinion as to 
 its affinities beyond the negative one, that it certainly has no 
 relationships with the Ctuetetida proper; while such resem- 
 blances as it shows to certain of the Monticuliporida are 
 largely counterbalanced by special and apparently inexplicable 
 peculiarities of its own. 
 
CHAPTER II. 
 
 THE FAVOSITID^:. 
 
 THE principal characters of this family have been already 
 given, and merely need brief recapitulation here. The coral- 
 lum whatever its form may be is usually composed of more 
 or less prismatic corallites, which are generally in complete 
 contact throughout, and have well-developed walls, which are 
 perforated by a greater or less number of " mural pores," or 
 apertures, by which the visceral cavities of contiguous pol- 
 ypes are placed in direct communication. There is no true 
 ccenenchyma, and the condition of the septa is extremely 
 variable, while tabulae are usually numerous and complete. 
 
 As regards the above characters, the general form of the 
 corallum is for the most part either massive or dendroid ; but it 
 is sometimes lamellar or frondescent (some types of Pachypora 
 and Ccenites) ; and Romingeria, Nich., affords an example of a 
 subfasciculate corallum, as to a less extent does also the genus 
 Vermipora, Hall. The corallites radiate from the base in the 
 massive forms, from an imaginary axial line in the dendroid 
 types, and from an imaginary axial plane in the frondescent 
 species ; and their general form is more or less conspicuously 
 prismatic or polygonal. This is seen in almost all those 
 coralla in which the corallites are closely contiguous (Favo- 
 sites y Lam., Syringolites, Hinde, Michelinia, De Kon., Nycto- 
 pora, Nich., &c.) There are species, however, even of such 
 forms as the above, in which the corallites are subcylindrical. 
 In other cases (Alveolites, Lam., Ccenites, Eichw., and some 
 
FA VOSITIDJE. 31 
 
 forms of Packypora, Lindstr.) the corallites are very much 
 compressed and flattened in form, becoming oval or sub- 
 triangular in shape. In other cases, again, the corallites are 
 partly contiguous and partly free (Vermipora, Hall, Romin- 
 geria, Nich., Chonostegites, E. and H., &c.), and in these 
 cases the corallites are prismatic where in contact, and more 
 or less cylindrical where free. In all the Favositida, however, 
 the corallites of the colony are in contact in some portions of 
 their extent. Wherever contact occurs, the walls of the coral-r 
 lites enter into a certain degree of union, though the extent of 
 this varies in different cases. In most of the Favositidce (in- 
 cluding all the typical forms) thin sections show that the 
 corallites always retain their proper walls, however closely 
 amalgamated they may appear to be ; so that the boundaries 
 of contiguous tubes are distinctly marked out by conspicuous 
 dark lines. Hence, also, weathered or fractured surfaces 
 usually (though not always) show the outsides of the coral- 
 lites. In one genus only (Nyctopora, Nich.) the fusion of 
 the walls of contiguous corallites appears to be complete. 
 
 As a general rule the walls of the corallites are not specially 
 thickened ; but in certain types (Packypora, Lindstr., Striato- 
 pora, Hall, Trackypora, E. and H., and Ccenites, Eichw.), the 
 visceral chambers of the polypes become contracted by the 
 secondary deposition of dense sclerenchyma in concentric 
 lamellee, the amount of this deposit increasing as the calices 
 are approached. In Stenopora, Lonsd., this thickening of 
 the tubes takes place periodically, and the terminal portions 
 of the corallites become thereby periodically annulated on 
 their outer surface, the intervening non- thickened portions 
 being not in actual contact. In some cases this thickening 
 of the walls of the corallites takes place to such an extent 
 (as in Trackypora, E. and H.) as to give rise to all the 
 appearances which would be produced if the tubes were 
 embedded in a dense " ccenenchyma ; " and the existence 
 of such a structure has often been affirmed. Microscopic 
 sections, however, show that the calcareous tissue separating 
 
32 TABULATE CORALS. 
 
 the actual visceral cavities is of endothecal origin ; and I have 
 seen nothing of the nature of a true " ccenenchyma" in any of 
 the Favositidce. 
 
 Wherever the walls of the corallites in the Favositidce come 
 in contact with one another, a communication between the vis- 
 ceral chambers of the polypes is effected by means of the 
 " mural pores." These are, typically, very definite apertures, 
 usually arranged in some serial order; and for the most part 
 so small and so widely apart, that they do not appreciably inter- 
 fere with the compactness and integrity of the wall as a distinct 
 structure. In the Silurian genus Columnopora, Nich., the pores 
 are so numerous and close-set that, though regular in form and 
 arrangement, they give the wall a cribriform aspect ; in the 
 Cretaceous Koninckia, E. and H., the pores are equally numer- 
 ous, but apparently irregular ; while in the Devonian Arceopora, 
 Nich. and Eth. jun., the trabecular condition of the wall is 
 quite like that of the typical Perforate Corals. In these 
 forms, therefore, we have a more or less complete approxi- 
 mation to the condition of parts in Alveopora (fig. 13), a recent 
 Madreporarian, in which tabulae are developed. It is hardly 
 
 Fig- '3- A, Vertical section of Alreopora spongiosa, Dana, showing the porous walls and the 
 tabulae and (B) two calices of the same, enlarged. Recent. (After Dana.) 
 
 necessary to add that in those members of the Favositida in 
 which the corallites are partially disjunct, the mural pores 
 only exist in places where the tubes are in actual contact. 
 
 The condition of the septa varies extremely in the Favo- 
 sitidce, though it is only in some few forms that these struc- 
 
FA VOSITID&. 
 
 33 
 
 tures appear to be wholly obsolete (e.g., in Stenopora, Lonsd.) 
 The most typical condition of matters is, that the septa should 
 be present in the form of vertically disposed rows of longer or 
 shorter spinules. The number of these vertical rows varies, 
 but is most commonly between ten or twenty. In Ccenites, 
 Eichw., the septa are reduced to one or more tooth-like ridges, 
 which appear to be confined to the thickened portions of the 
 tubes, close to their mouths; and in Alveolites, Lam., a similar 
 reduction of the septa may take place, though the walls are not 
 thickened, and the septa may be wholly wanting. In Arceopora, 
 Nich. and Eth. jun., the septa subdivide and anastomose with 
 one another to a greater or less extent; and in Nyctopora, 
 Nich., they assume the form of marginal ridges or lamellae, 
 their typical spiniform character being lost. 
 
 Lastly, the visceral chamber in all the Favositida is inter- 
 sected by a greater or less number of transverse partitions or 
 " tabulae." Typically, these tabulae are " complete " that is to 
 say, they pass completely across the visceral chamber as so 
 many unbroken horizontal plates ; but this is not invariably 
 the case. Sometimes, however (as in Favosites hemispherica, 
 Yand. and Shumard), the tabulae are " incomplete," having the 
 form of tongue-shaped laminae, which project to a greater or 
 less extent into the visceral chamber, often anastomosing or 
 dividing at their free edges, but not passing quite across the 
 tube. Very commonly " complete " and " incomplete " tabulae 
 are found coexisting ; and this is particularly the case with the 
 comparatively rudimentary and imperfect tabulae which occur 
 in many species of Favosites, and which Dr Rominger terms 
 "squamulae," assigning to them, as I think erroneously, a 
 septal origin. Finally, there are genera, such as Michelinia, 
 De Kon., in which the tabulae are convex, and unite so freely 
 among one another as to give rise to a kind of subvesicular 
 tissue, not unlike the cellular tissue which fills the visceral 
 chamber of the Cystiphyllidce, though usually much less per- 
 fectly vesicular, and interrupted every now and then by a 
 complete tabula. 
 
 c 
 
34 TABULATE CORALS. 
 
 The zoological affinities of the Favositidce > as has been seen, 
 are with the Zoantharia Perforata, and the family may find a 
 place close to the Poritidce. The typical genera of the Favo- 
 sitidce (Favosites, Lam., Alveolites, Lam., Michelinia, De Kon., 
 &c.) are distinguished from the typical Poritidce by the much 
 more complete development of the walls of the corallites, by 
 the reduction of the channels of communication between the 
 visceral chambers of contiguous polypes to comparatively 
 minute and for the most part serially-arranged " pores," and 
 by the presence of well -developed tabulae. On the other 
 hand, the Cretaceous Koninckia, E. and H., and the Devonian 
 Arczopora, Nich. and Eth. jun., have the walls so highly cribri- 
 form and the tabulae so greatly reduced that they might per- 
 fectly well be placed in the family of the Poritidce. in the 
 vicinity of the recent Alveopora, Quoy and Gaim. (fig. 13), and 
 Favositipora, Sav. Kent. The link between these extreme 
 forms is effected by such a type as the Lower Silurian Colum- 
 nopora, Nich., which has highly but regularly perforated walls, 
 combined with numerous complete tabulae and lamellar though 
 rudimentary septa. Another group of the Favositidce is con- 
 stituted by Pachypora, Lindstrom, Striatopora, Hall, Trachy- 
 pora, E. and H., Dendropora, Mich., and Ccenites, Eichw. in 
 all of which the cavities of the polypes are more or less con- 
 tracted by the deposition of sclerenchyma on the interior of 
 the walls of the corallites. Many of these forms consequently 
 assume an appearance extremely similar to that of the recent 
 Pocillopora, Lam., and Seriatopora, Lam., from which, however, 
 they are fundamentally separated by the absence of a ccenen- 
 chyma and by their perforated walls. The genus Stenopora, 
 Lonsd., though possessing peculiarly thickened walls, exhibits 
 so many other anomalous features that it cannot be associated 
 with the preceding, but must rather be regarded as a special 
 type. The genus Syringolites, Hinde, though in many re- 
 spects entirely like a Favosites, possesses funnel-shaped tabulae, 
 which give rise to an axial tube in the centre of each corallite 
 thus forming an interesting link between the Favositidce and 
 
FA VOSITIDAL. 
 
 35 
 
 the Syringoporida. The genus Romingeria, Nich. (= Quenstedtia, 
 Rom.), is, again, curiously transitional between the Favositidce 
 and the Auloporidce, having the mural pores of the former 
 combined with corallites of the general type of the latter. 
 Lastly, the genus Nyctopora, Nich., affords a link between the 
 Favositidte on the one hand, and the apparently Aporose 
 group of the Columnariadce on the other hand. 
 
 The following is a list of the genera which I include under 
 the Favositida, with the geological distribution of each. It 
 must be remembered, however, that two or three of these types 
 are at present imperfectly understood, and may prove to have 
 different affinities ; while two or three might with almost equal 
 propriety be included in the family of the Poritidce ; and future 
 researches will doubtless show that other generic forms will 
 have to be added to the list : 
 
 Genus. 
 
 Favosites, Lam., 
 Alveolites, Lam., . 
 Vermipora, Hall, . 
 
 Michetinia, De Kon., . 
 
 Pleurodictyum, Goldf., . 
 Chonostegites, E. and H. (- ) 
 
 Haimeophyttum,tih,\ } 
 
 Pachypora, Lindstr., 
 Striatopora, Hall, . 
 Trachypora, E. and H. (with 
 
 Dendropora, Mich., and 
 
 Rhabdopora, M'Coy), 
 Ccenites, Eichw., . 
 Columnopora, Nich., 
 Koninckia, E. and H. . 
 Favositipora, Sav. Kent (? ) 
 
 Poritidcz), ) 
 
 Arczopora, Nich. and Eth. ) 
 
 Jun. (? PoritidcE), } 
 
 Rosmeria, E. and H. (? Syr- 
 
 ingoporidce), J 
 
 Syringolites, Hinde, 
 Nyctopora, Nich., . 
 
 Geological range. 
 . Silurian to Carboniferous. 
 . Silurian and Devonian. 
 . Silurian and Devonian. 
 
 t Upper Silurian (?), Devonian and 
 J Carboniferous (perhaps = Pleuro- 
 
 ( dtctyum, Goldf.) 
 . Upper Silurian ? and Devonian. 
 
 . Devonian. 
 
 . Upper Silurian and Devonian. 
 . Upper Silurian and Devonian. 
 
 . Devonian and Carboniferous. 
 
 . Silurian and Devonian. 
 . Silurian. 
 . Cretaceous. 
 
 . Recent. 
 . Devonian. 
 
 . Devonian. 
 
 . Upper Silurian. 
 Lower Silurian. 
 
 I 
 
3 6 TABULATE CORALS. 
 
 Genus. Geological range. 
 
 Romingeria, Nich. ( = Qiien- ) Devonian. 
 stedtia, Rominger), J 
 
 f Carboniferous and Permo-Carbonifer- 
 Stenopora, Lonsd. { 
 
 ( ous ; (?) Permian also. 
 
 illingsia, De Koninck, . . Devonian. 
 
 Laceripora, Eichw. (imperfect- ) _ ^ ^.^ ^ Carboniferous . 
 
 ly known), 
 
 Nodulipora, Lindstr. . . . Upper Silurian. 
 
 An examination of the above list shows that of the twenty- 
 two genera placed in the Favositidce no less than twenty are 
 Palaeozoic; so that this group of Perforate Corals enjoyed, 
 therefore, a great extension at this early period. Koninckia 
 is the only Cretaceous genus, and Favositipora the only recent 
 one ; and both might find a place in the Poritidce, near Alveo- 
 pora. Moreover, the group attained its maximum develop- 
 ment in Upper Silurian and Devonian times ; very few types 
 survive into the Carboniferous period ; and perhaps the only 
 one existing in the Permian is Stenopora. Indeed the great 
 abundance of these Palace-Perforate Corals in the Devonian, 
 and their very scanty representation in the Carboniferous, may 
 be taken as one of the strongest of the palaeontological proofs 
 that the periods so named are geologically distinct. Lastly, the 
 almost total absence of examples belonging to the Favositida 
 in Secondary and Tertiary deposits affords an indication that 
 the family is more than a mere sub-group of the now widely 
 distributed Poritidcz. 
 
37 
 
 CHAPTER III. 
 
 GENERA OF FAVOSITID^E. 
 
 Genus FAVOSITES, Lamarck, 1816. 
 (Hist, des An. sans Vert, vol. ii. p. 204.) 
 
 Calamopora, Goldfuss, Petref. Germ., vol. i. p. 77, 1826. 
 
 Emmonsia, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 246, 1851. 
 
 Astrocerium, Hall, Pal. N.Y., vol. ii. p. 120, 1851. 
 
 Gen. Char. Corallum massive or branched, composed of nu- 
 merous more or less conspicuously polygonal corallites, which 
 are in close contact with one another, but are not amalga- 
 mated by their walls. Walls lamellar, perforated with one 
 or more rows of circular " mural pores," by which the separate 
 corallites are placed in communication. Visceral chamber in- 
 tersected by a greater or less number of complete or incom- 
 plete transverse partitions or " tabulae." Septa obsolete, or 
 represented by vertical rows of tubercles or pointed spines. 
 
 The general form of the corallum in this genus is very vari- 
 able, but the most typical species (e.g., F. Gothlandica, Lam.) 
 possess a discoidal, hemispherical, or subglobular skeleton, of a 
 massive character, and often attaining very considerable dimen- 
 sions. Other forms, again, have the habit of growing in cylin- 
 drical or flattened ramose expansions ; but most of the so-called 
 " dendroid " species of Favosites may be placed under allied 
 generic types. The forms with a discoidal or expanded, and 
 
3 8 TABULATE CORALS. 
 
 those with a hemispherical or globose corallum, have the lower 
 surface covered with a thinner or thicker, concentrically-striated 
 epitheca, while the calices are placed upon the upper surface. 
 The ramose species possess no true epitheca. 
 
 In the massive and more typical species the corallum is fixed 
 by a portion of its base to some foreign body ; and from this 
 point the long and prismatic corallites radiate to the surface, 
 those in the centre of the mass being nearly vertical in direc- 
 tion, while those towards the margins become more and more 
 inclined, till they become nearly or quite parallel with the 
 lower surface. New corallites are intercalated by gemmation, 
 as the tubes proceed towards the surface. In the ramose 
 species, the corallites are vertical in the centre of the branches, 
 and gradually bend outwards, in a radiating manner, till they 
 open on the circumference in a direction more or less nearly 
 rectangular to the surface. 
 
 The corallites are typically markedly prismatic, usually pen- 
 tagonal or hexagonal, but they may become more or less cylin- 
 drical in whole or in part. The tubes are never united by the 
 actual fusion of their walls, though always in contact, and 
 their walls are typically of no great thickness. In some forms, 
 however, which have been commonly referred to Favosites, but 
 which will here be placed under the allied genus Pachypora, 
 Lindstrom, the walls are extraordinarily thickened by a second- 
 ary deposit of sclerenchyma, and we find an approximation to 
 this in some species which must still be left in Favosites proper. 
 In all the species of Favosites, further, the visceral chambers of 
 contiguous corallites are placed in communication by means of 
 a series of circular apertures or " mural pores." These fora- 
 mina are usually arranged in a regular manner; and though 
 this arrangement is not absolutely constant for, perhaps, any 
 given species, still it is approximately uniform in its character, 
 and thus affords a useful guide in specific diagnosis. Thus, in 
 certain species (e.g., F. turbinata, Bill.) the pores are typically 
 uniserial that is to say, each of the flat faces of the prismatic 
 corallites carries a single row of these apertures. In another 
 
GENERA OF FAVOSITID^E. 39 
 
 series of types (e.g., F. Gothlandica, Lam.) the pores are bi- 
 serial, each prismatic face of the corallites carrying two rows, 
 usually placed alternately. In other forms, again, the pores 
 are triserial; while some species (e.g., F. alveolaris, Goldf., and 
 F. aspera, D'Orb.) are distinguished by the peculiarity that the 
 pores are situated in the angles formed by the prismatic walls 
 of the corallites, instead of on their flat faces. Very commonly 
 the pores are surrounded each by a raised rim or margin, but 
 this may be replaced by a circular pit, or the surface may be 
 quite plane. It should, lastly, be noticed in this connection, 
 that the mural pores are commonly very difficult of detection, 
 even in specimens otherwise perfectly well preserved, by even 
 the closest external examination. Very commonly in calca- 
 reous specimens, and sometimes in those which are silicified 
 (especially -in those where the silica has assumed the " orbicu- 
 lar " form), the walls of the corallites appear to be completely 
 imperforate under a hand-lens, or even under the microscope. 
 Thin sections, however, when taken parallel with the axis of 
 the tubes, will generally, in some part or another, coincide with 
 the plane of the wall of a corallite, and will then exhibit the 
 mural pores with greater or less distinctness. 
 
 The calices of the typical species of Favosites are placed 
 parallel with, and not elevated above, the general surface ; but 
 in some forms which have not yet been clearly separated from 
 this genus, the calices open more or less obliquely to the surface, 
 and the lower lip of the calice is more or less elevated and pro- 
 jecting. In a few singular types (F. turbinata, Bill., F. For- 
 besi, var. tuberosa, Rom., F. clausus, Rom., &c.) there is the 
 singular feature that the calices in a larger or smaller number 
 of the corallites become closed by a calcareous lid or " opercu- 
 lum." Sometimes this seems to be merely the result of a con- 
 tinuous growth of the epitheca upwards ; but in other cases 
 the operculum would seem to be formed by successively 
 deposited concentric layers of calcareous matter, which spring 
 from the margins of the calice, and gradually close in towards 
 its centre. In the species above mentioned all of which are 
 
40 TABULATE CORALS. 
 
 Devonian this curious feature seems to be one normal to the 
 species, being more or less fully developed in all perfect ex- 
 amples. In other species, however, it would appear to be only 
 an occasional phenomenon. Dr Lindstrom has recognised the 
 same peculiarity as an occasional thing in examples of the 
 Upper Silurian F. Forbesi, E. and H., and also in his Vermipora 
 (Fletcheria) clausa, from the same formation (Ofversigt af K. 
 Vetensk. Akad Forhandlingar, 1865, PI. XXX.) 
 
 Septa are so commonly obsolete in Favosites, or are so 
 rudimentary, that these structures were supposed to be gener- 
 ally altogether absent in the species of this genus. In reality, 
 however, the septa must be regarded as constituting one of the 
 most variable of the structures of a very variable group, and 
 not even specific value can be attached to their presence or 
 absence, or to the degree of their development when present. 
 In some cases there are absolutely no traces of septa, even in 
 specimens examined by means of microscopic sections. More 
 commonly the septa can be recognised as so many longitudinal 
 striae or ridges on the interior of the tube, each ridge being 
 really made up of a vertical series of tubercles. In other cases, 
 again, the septa have the form of radiating spines, which may 
 reach very nearly to the centre of the visceral chamber, though 
 usually considerably shorter than this. In no case are regular 
 lamellar septa developed. All the above conditions of the 
 septa namely, their presence as radiating spines in superposed 
 rows, their development as tubercles arranged in ridges, or 
 their total absence may be occasionally recognised in different 
 examples of the same species, or even in different parts of the 
 same specimen. The number of the septal ridges or spines, 
 when developed at all, is not constant, but appears to be most 
 commonly from twelve to fifteen. 
 
 The genus Astrocerium, Hall (loc. /.), was founded upon 
 examples of Favorites, in which spiniform septa are developed ; 
 but the variability of this character renders this division an 
 untenable one. 
 
 The tabulae in the most typical forms of Favosites are com- 
 
GENERA OF FAVOSITID^E. 41 
 
 plete transverse partitions, which are placed at variable 
 distances, and rarely anastomose. Most usually, the tabulae 
 are approximately horizontal ; but they may be markedly con- 
 vex or concave. Certain species (F. favosa, Goldf.) have been 
 distinguished by the curvature of the tabulae ; but this appears 
 to be a very variable character, differing even in different parts 
 of the same specimen, and it cannot be employed in the diag- 
 nosis of species. Similarly, it is not uncommon to find that 
 the tabulae are so bent as to give rise to a series of marginal 
 pits or depressions, which in some specimens are extremely 
 regular, and impart an apparently characteristic appearance to 
 the tubes. This feature, however, is also not constant, even 
 in the same individual, and cannot be looked upon as of 
 specific value. 
 
 While the typical species of Favosites possess " complete " 
 tabulae, there are others in which these structures have the 
 form of imperfect plates, which extend into the visceral cham- 
 ber transverse to its axis, but do not divide it into a succession 
 of completely separate vertical storeys. These " incomplete " 
 tabulae were regarded by Milne-Edwards and Haime as being 
 of generic value, and these authors placed all those forms 
 possessing them in the genus Emmonsia (loc. jam cit.) The 
 fact, however, that it is by no means uncommon to meet with 
 single specimens in which some of the tubes have the irregular 
 and incomplete tabulae of Emmonsia, while others have the 
 regular and complete tabulae of the type-forms of Favosites 
 the same tube sometimes exhibiting both these conditions in 
 different parts of its course is quite sufficient 'to show that the 
 separation of Emmonsia as a distinct genus cannot be carried 
 out in practice. 
 
 Lastly, there are various species of Favosites in which, in 
 addition to, or in the absence of, complete tabulae, the inner 
 surfaces of the tubes are rendered rough by the presence of 
 numerous horizontal projecting lamellae, which extend only a 
 short distance into the visceral chamber, and which often have 
 a more or less leaf -like or tongue -like character. These 
 
42 TABULATE CORALS. 
 
 singular structures the " squamulse " of Dr Rominger are 
 particularly characteristic of certain Devonian forms, but they 
 occur also in the Upper Silurian F. Forbesi. We cannot, 
 therefore, accept the statement made by Dr Rominger (Foss. 
 Cor. of Michigan, p. 19), that "the Silurian forms differ from 
 the Devonian Favosites by invariably having simple dia- 
 phragms, and by the spinulose character of their radial crests." 
 At least one Silurian species of the genus, on the contrary, is 
 known to possess imperfect tabulae as a variation ; and many 
 forms exhibit no septa (" radial crests ") at all, or only rows of 
 tubercles. Nor can we accept the view held by Dr Rominger, 
 that the " squamulae " of certain species of Favosites are really 
 of the nature of septa. On the contrary, the fact that their 
 direction is one transverse to the axis of the visceral cavity, 
 and that they commonly occupy the entire width of one of the 
 prismatic faces of a corallite, entirely precludes our believing 
 that they can have been situated in the inside of one of the 
 " mesenteries " of the living animal, and is thus fatal to the con- 
 ception of their septal character. They must, on the other hand, 
 be regarded as a peculiar modification of the tabulce of the more 
 typical species, and they not uncommonly coexist with these. 
 
 In no case known to me are the tabulae of Favosites in- 
 fundibuliform, or invaginated one into the other ; and this 
 leads me to say a few words as to the genus Calamopora of 
 Goldfuss, and as to the propriety of the course followed by 
 many Continental palaeontologists in substituting the latter 
 name for the former. The actual definition of Calamopora 
 given by Goldfuss (Petref. Germ., p. 72) is as follows : 
 
 " Stirps calcarea, e tubis prismaticis parallelis contiguis 
 diver gentibus. Tubi diaphragmatibus transversis (e siphone 
 prolifero) inter septi, et poris later alibus communicantes" 
 
 Not only do his subsequent descriptions and figures render 
 it certain that the forms included under this head by Goldfuss 
 are precisely the same as those long before placed by Lamarck 
 under Favosites, but he himself admits this ; and the only new 
 characters which he gives are to be found in the words "e siph- 
 
. GENERA OF FA VOSITID^E. 43 
 
 one prolifero," as indicating the structure of the tabulae. Gold- 
 fuss himself, however, in the vernacular description which 
 follows the brief Latin diagnosis, confesses that " nur bei einer 
 Art erscheinen sie " (the tabulse) " als trichterformige Prolifera- 
 tion eines Sipho." The one species to which he alludes is his 
 Calamopora infundibulifera, which is in all its characters very 
 distinct from the older genus Favosites of Lamarck, and which 
 is only very doubtfully referable to the family of the Favositida 
 at all, since it has never been proved to possess mural pores. 
 Nor can it even be asserted that the tabulse in this type spring 
 from or form an actual central tube or " siphon " they simply 
 appear to be funnel-shaped and invaginated. Considering, 
 then, that all the other species included by Goldfuss under 
 Calamopora are undoubtedly destitute of the median siphon 
 implied by this generic name, and that most of them are clearly 
 identical with the forms previously designated Favosites by 
 Lamarck, it does not appear that there is the slightest ground 
 for the course adopted by some of the most distinguished of 
 living German palaeontologists, who still regard Favosites, 
 Lam., as a mere synonym of Calamopora, Gold. 
 
 I shall have occasion, however, to point out subsequently 
 that there really does exist a coral (Syringolites, Hinde) which 
 actually possesses the median tube imagined by Goldfuss to 
 be present in his Calamopora, and for which, therefore, this 
 name might be retained, if it were at all advisable to try and 
 revive a genus founded upon so many forms of different affin- 
 ities. The coral in question, however, in no way agrees with 
 any of the forms included by Goldfuss under the head of Cala- 
 mopora not even with C. infundibulifera, now known as 
 Rosmeria infundibulifera; and it is fully entitled to receive the 
 new generic designation Syringolites, Hinde, under which name 
 I shall briefly describe it later on. 
 
 Of the other genera of the Favositidce, Alveolites, Lam., 
 Pachypora, Lindst, and Striatopora, Hall, are probably those 
 which are most difficult to separate from Favosites proper. 
 Palaeontologists have recently shown a tendency to suppress 
 
44 TABULATE CORALS. 
 
 Alveolites altogether, as including types of very different 
 affinities ; but the name may be advantageously retained, in the 
 meanwhile at any rate, for forms like A. suborbicularis. Lam.; 
 though it is difficult to point to any characters which definitely 
 separate these from Favosites except their inclined corallites and 
 oblique calices. Pachypora and Striatopora, again, are hardly 
 separable from the dendroid forms of Favosites by anything 
 else except by the thickening of the walls of the corallites near 
 their mouths; and, in fact, even this distinction would fail 
 unless we remove from the latter category, as will here be 
 done, some forms which are usually included in it (such as 
 F. cristata, E. and H., and F. cervicornis, De Blainv.) The 
 position of Cladopora, Hall, I shall consider in dealing with 
 Pachypora. Fistulipora, M'Coy, can in general be readily dis- 
 tinguished from Favosites, both by the existence of two distinct 
 series of corallites, and by the absence in the former of mural 
 pores. There is, however, one species viz., Favosites (Fistu- 
 lipora) Canadensis, Bill., from the Devonian of Canada, which 
 ordinarily has all the external features of Fistulipora, but which 
 has been shown by Rominger to possess the mural pores of 
 Favosites, a fact which I can corroborate from an examination 
 of microscopic sections. Moreover, this transitional form some- 
 times loses the characteristic of possessing a series of large 
 corallites interspersed among numerous smaller ones, and 
 passes by insensible gradations into a type so similar to the 
 ordinary examples of Favosites, that it has been separated by 
 Dr Rominger, as I think without sufficient reason, to constitute 
 a new species under the name of F. placenta (Foss. Cor. of 
 Michigan, p. 32). 
 
 Michelinia, De Kon., is another close ally of Favosites, for 
 I am unable to agree with Dr Lindstrom in thinking that there 
 is any essential difference in the nature of the mural pores in 
 these two genera (On the Affinities of the Anthozoa Tabulata, 
 Ann. and Mag. Nat. Hist., ser. 4, vol. xviii. p. 12). It differs 
 from Favosites almost exclusively in the complex character of 
 its tabulae. 
 
GENERA OF FA VOSITID&. 45 
 
 Syringolites, Hinde, while possessing the general structure 
 and habit of Favosites, is entirely separated from it by the fact 
 that the tabulae are infundibuliform, giving rise to a central 
 tube in the axis of the visceral chamber of each corallite ; the 
 genus thus forming a connecting-link between Favosites and 
 
 o o o 
 
 certain forms of Syringopora. 
 
 Lastly, Columnopora, Nich., is closely allied to Favosites^ 
 but is distinguished by the less intimate union of the corallites, 
 and by the greater development of the system of mural pores, 
 the walls thus becoming completely cribriform. 
 
 As regards the geological range of Favosites, it may be stated 
 with certainty that the genus attained its maximum during the 
 Upper Silurian and Devonian periods. It probably existed 
 during the Lower Silurian, though the evidence available on 
 this point is not absolutely satisfactory ; and it was certainly 
 continued into the Carboniferous. The existence, also, of a 
 recent coral which is hardly separable from Favosites proper 
 namely, the Favositipora of Saville Kent would indicate that 
 the genus will yet be found in the Secondary and Tertiary 
 deposits, either unmodified or under some allied form. Koninc- 
 kia, E. and H., of the White Chalk, differing from Favosites 
 chiefly in its larger and more approximated mural pores, offers 
 one of these desired continuations of this ancient Ccelenterate 
 type ; and my friend Professor C. A. White has recently shown 
 me a coral from the Cretaceous deposits of North America, 
 which assuredly could not be separated from Favosites otherwise 
 than by the apparent possibly only apparent absence of 
 mural pores. 
 
 As illustrative species of Favosites, I have selected F. Goth- 
 landica, Lam., F. Forbesi, E. and H., F. (Emmonsia) hemispher- 
 ica, E. and H., F. (Chcetetes] Bowerbanki, E. and H., and F. 
 clausa, Rom. the first three of these being massive forms, 
 while the last is a true dendroid species, and F. Bowerbanki 
 offers a transition between these two types. 
 
46 TABULATE CORALS. 
 
 Favosites Gothlandica, Lamarck. 1 
 (PI. L, figs. i-6.) 
 
 Favosites Gothlandica, Lamarck, Hist, des An. sans Vert., vol. ii. p. 206, 1816. 
 Calamopora Gothlandica, Goldfuss, Petref. Germ., PL XXVI., figs. 3 a, 3 b, 
 
 3 c, 3 e (cset. exclusis), 1829. 
 
 favosa, Goldfuss, Petref. Germ., PL XXVI., 2 a- 2 c, 1829. 
 Favosites Goldfussi, D'Orbigny, Prodr. de Pale'ont., vol. i. p. 107, 1850. 
 Gothlandica, M'Coy, Brit. Pal. Foss., p. 20, 1851. 
 Gothlandica, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 p. 232, 1851 ; and Brit. Foss. Cor., p. 256, PL LX., figs, i, i a, 
 1854. 
 
 Goldfussi, Milne- Edwards and Haime, Pol. Foss. des Terr. Pal., 
 p. 235, PL XX., fig. 3, 1851 ; and Brit. Foss. Cor., p. 214, PL 
 XLVIL, figs. 3-30 1853. 
 Niagarensis, Hall, Pal. N.Y., vol. ii. p. 125, PL XXXIV., A, bis, 
 
 fig- 4, 1851. 
 
 favosa (?), Hall, ibid., p. 126, PL XXXIV., bis, fig. 5, 1851. 
 Calamopora Gothlandica, Ferd. Roemer, Sil. Fauna des Westlichen Tenn., 
 
 pp. 18 and 19, figs. 9-9 and ii, 1860. 
 favosa, Ferd. Roemer, ibid., p. 18, fig. 8, 1860. 
 
 Favosites Gothlandica, Billings, Canad. Journ., new ser., vol. iv. p. 99, 1859. 
 Gothlandica, Nicholson, Report on the Palaeontology of Ontario, 
 
 1874, p. 45. 
 
 favosa, Nicholson, ibid., 1875, p. 51. 
 
 favosa, Nicholson, Palaeontology of Ohio, vol. ii. p. 229, 1875. 
 favosus, Rominger, Fossil Corals of Michigan, p. 20, PL IV., figs. 
 
 1-4, and PL V., fig. 2, 1876. 
 
 Niagarensis, Rominger, ibid., p. 22, PL V., fig. i. 
 Winchelli, Rominger, ibid., p. 31, PL IX., figs. 3 and 4, and Amer. 
 
 Journ. Sci. and Arts, 1862. 
 Billingsii, Rominger, ibid., p. 28. 
 
 Spec. Char. Corallum composite, forming discoidal, spher- 
 oidal, turbinate, or hemispherical masses of irregular shape and 
 size, the under surface being usually covered with an epitheca, 
 while the whole of the upper surface is occupied by the calices. 
 Corallites prismatic, usually between one line and one and a 
 
 1 In the list of references appended to this, as well as to the other species subse- 
 quently described, I have not attempted to give an absolutely exhaustive synonymy. 
 On the contrary, I have simply given those references which I have myself verified. 
 In some cases, of course, my verification has been based simply upon an author's 
 description or figures, and must therefore be considered merely as an expression 
 of personal opinion. In the majority of cases, however, my determination has 
 been founded upon an examination of actual specimens derived from the same 
 formation as that which yielded examples to the author quoted. 
 
GENERA OF FA VOSITID&. 47 
 
 half line in diameter, sometimes less, and often more. Calices 
 regularly polygonal, with thin walls, generally tolerably uniform 
 in size in any given specimen, but always having smaller and 
 younger ones intercalated among those of average size. Walls 
 of the corallites not thickened towards their mouths, sometimes 
 longitudinally striated on their flat faces, and furnished with 
 two (sometimes one or three) rows of mural pores on each 
 prismatic face. Pores alternately placed, surrounded by an 
 elevated margin. Tabulse complete, rarely inosculating ; some- 
 times incomplete and inosculating in parts of a colony, while 
 complete in others. Septa usually obsolete or irrecognisable, 
 sometimes represented by rows of tubercles or even by well- 
 developed radiating spines. 
 
 Obs. If the forms which I have here admitted under the 
 head of F. Gothlandica, be really referable to this form, then it 
 must be allowed that we have to deal here with one of the most 
 variable species of a variable genus. All the above, however 
 (with some others not included in this list), are clearly descen- 
 dants of a single stock, belonging to the same type-form, differ- 
 ing only in characters of comparatively trivial importance, and 
 for the most part insensibly passing into one another by the 
 intervention of examples possessing intermediate characters. 
 Some of the forms included in the series are so far distinct 
 that they may well retain distinct varietal appellations ; but 
 their general relationships are so close that I have thought it 
 best to collect them under a single specific title, rather than 
 to follow some high authorities in treating each as a separate 
 species. 
 
 Favosites Gothlandica was originally described from speci- 
 mens found in the Wenlock Limestone of the island of Got- 
 land (Lamarck, he. ?.), and this name was restricted by 
 Milne-Edwards and Haime to forms occurring in the Silurian, 
 the species not being admitted as a Devonian one. We may 
 therefore properly regard the form which occurs so commonly 
 in the Upper Silurian of Europe, and which palaeontologists 
 have so long recognised under the name of F. Gothlandica, 
 
4 8 
 
 TABULATE CORALS. 
 
 as the type of the species. Examples specifically inseparable 
 from this are, however, found in the Devonian of both the 
 Old and New Worlds ; so that the species had a very wide 
 
 Fig. 14. A, A specimen of Favosites Gothlandica, Lam., from the Niagara Limestone (Wen- 
 lock) of Owen Sound, Ontario, of the natural size ; B, A small example of the same 
 species from the Wenlock Limestone of Dudley, with comparatively minute corallites, 
 of the natural size; c, Fragment of the same species, with large-sized corallites, from the 
 Wenlock Limestone of Gotland, of the natural size ; D, Part of two corallites of the 
 same species, from the Corniferous Limestone (Devonian) of Woodstock, Ontario, 
 slightly enlarged. 
 
 range both in space and in time : and there are various other 
 Silurian and Devonian forms of Favosites which, as before said, 
 appear to be nothing more than variations of this type-form. 
 Having had the opportunity of making a careful examination, 
 microscopic and macroscopic, of a very extensive series of such 
 forms, collected from the Silurian and Devonian deposits of 
 both America and Europe, I shall in what follows briefly 
 record the results of my researches as bearing upon the 
 structural characters of the species. 
 
GENERA OF FAVOSITID^E. 49 
 
 The general shape of the coratlum of Favosites Gothlandica 
 is very variable ; and its size differs still more either in speci- 
 mens of different ages, or in specimens derived from different 
 formations. Typical examples, from the Upper Silurian, are 
 generally more or less hemispherical or discoidal, with a de- 
 pressed or slightly convex upper surface (fig. 14, B), the cor- 
 allum being attached to some foreign body by the centre of 
 its base, which is sometimes drawn out into a short peduncle. 
 The lower surface is also covered with a thin, smooth, or con- 
 centrically-striated epitheca, which is commonly worn off in 
 old specimens, though sometimes greatly thickened. Average 
 examples of this kind are usually two or three inches in dia- 
 meter, sometimes more, with a height of three quarters of an 
 inch to an inch ; but I have figured a small example the 
 youngest I have seen from the Wenlock Limestone of 
 Dudley, in which the diameter is only about eight lines, with 
 a height of three lines (PI. I., fig. 3). In the Devonian, the 
 species seems to have assumed a much greater luxuriance of 
 growth, examples of much larger size and of very variable form 
 being far from uncommon. Even the larger specimens, how- 
 ever, seem to preserve the same general type namely, that of 
 a flattened or hemispherical expansion, attached by a portion of 
 its base, and having its inferior surface covered by an epitheca. 
 
 The corallites in the typical Upper Silurian examples of F. 
 Gothlandica are prismatic, thin-walled, usually pentagonal or 
 hexagonal, and very regular in form and size in any given 
 example (see fig. 14, A and B, and PI. I., figs, i and 2). The 
 calices, of course, have a corresponding polygonal form and 
 regularity of outline ; and here we seem to reach one of the 
 most distinctive characters of the species. It need hardly be 
 said that in no specimen are the corallites absolutely uniform 
 in size or form. In every individual example, the corallum 
 consists of younger and older, and therefore of smaller and 
 bigger, tubes, and the form of these necessarily varies with 
 variations in the pressure to which each is subjected by its 
 neighbours. Still, the average corallites of any particular speci- 
 
 D 
 
5 o TABULATE CORALS. 
 
 men of F. Gothlandica are wonderfully similar in size and 
 shape, being strikingly and often regularly pentagonal or hex- 
 agonal, and being further distinguished in thin sections by the 
 thinness of their walls (PI. I., figs, i and 2). In no case do the 
 larger calices assume the rounded character of those of F. For- 
 besi, nor is there the same conspicuous interpolation of small 
 tubes among the larger ones. All the forms which I have 
 here included under F. Gothlandica agree in the possession of 
 these regularly prismatic, thin-walled tubes ; and this being the 
 case, it remains to be considered if the size of the average 
 corallites can be properly considered as a specific character. 
 Most palaeontologists have answered this question in the affir- 
 mative, and have given names to species separated from the 
 typical F. Gothlandica principally or solely on account of the 
 average size of the corallites. Mr Billings, however, long ago 
 gave reasons for thinking that this character was one upon 
 which little stress could be laid (Canad. Journ., new ser., vol. 
 iv.), and my own researches have led me to entirely coincide in 
 this opinion. The examples which I have examined from the 
 Upper Silurian, and about the determination of which I enter- 
 tain no doubt, show conclusively the small weight that can be 
 attached to the mere size of the corallites. Those from the 
 Wenlock Limestone of Dudley, Longhope, and Benthall Edge, 
 have tubes of an average size of one line, some a little less, 
 some a little more (as stated by M'Coy, and also by Milne- 
 Edwards and Haime in their Monograph of the British Fossil 
 Corals). Those from the Wenlock Limestone of Gotland 
 (kindly sent to me and specifically determined by my friend 
 Dr Lindstrom) have usually a diameter of from one and a half 
 to two lines (agreeing, on the whole, with the measurements 
 given by Milne- Edwards and Haime in their work on the 
 Polypiers fossiles des terr. Pal.) ; but in one example the 
 tubes have a diameter of fully three lines (fig. 14, c). Lastly, 
 t ? iose from the Niagara Limestone (Wenlock) of North Amer- 
 ica have mostly tubes of an average diameter of a line and a 
 half, this being sometimes reduced to a line or less, or increased 
 
GENERA OF FAVOSITID^E. 51 
 
 to three lines (PI. I., figs. 4 and 5). The Devonian examples 
 which I should place in this species, possess an equal variability 
 in this respect; and it is therefore clear that the diameter of 
 the corallites even when we look only to the average tubes 
 of a given specimen cannot, in the case of F. Gothlandica, 
 be regarded as a character of specific value. It is further clear 
 that forms said to be specifically distinct from F. Gothlandica 
 must be proved to possess some character of greater constancy 
 and persistence than the mere size of the average corallites, 
 before their claims for separate recognition can be allowed. 
 
 The walls of the corallites of F. Gothlandica usually have 
 the outer surface smooth, or marked with delicate transverse 
 lines, which indicate the position of the tabulae within. In 
 specimens, however, which cannot be otherwise separated from 
 F. Gothlandica (as previously shown by Mr Billings, loc. cit.), 
 it is not unusual to find the flat outer faces of the corallites 
 exhibiting one or two longitudinal lines or striae separating 
 the rows of mural pores. This is the chief or only character of 
 importance which Milne-Edwards and Haime adduce in their 
 definition of F. Troostii, as separating this species from allied 
 forms ; and its occurrence in well-marked Devonian examples 
 of F. Gothlandica as here understood would seem to greatly 
 diminish or altogether destroy its value as a test of specific 
 distinctness. 
 
 The imiral pores of all the typical examples of F. Gothlan- 
 dica, both from the Upper Silurian and Devonian, are arranged 
 in a double row upon each of the prismatic faces of the coral- 
 lites, those of the two rows alternating with one another, and 
 each being separated from its neighbour by a space of about 
 half a line, measured vertically, and surrounded by a slightly 
 raised rim or border (fig. 14, D). These are certainly the 
 general characters of the mural pores in F. Gothlandica, and 
 they would serve as admirable guides to a specific determina- 
 tion if they could be at all constantly determined, or were in 
 themselves constant in their occurrence. In a great many 
 specimens, however, even though apparently excellently pre- 
 
5 2 TABULATE CORALS. 
 
 served otherwise, and whether calcareous or silicified, it is quite 
 impossible to determine the arrangement of the mural pores, 
 or even to satisfy one's self of their existence ; while microscopic 
 sections afford only a casual help, since they do not show these 
 openings except when and where they happen to coincide with 
 the plane of one of the bounding walls of a corallite. More- 
 over, the arrangement of the pores does not seem to be abso- 
 lutely constant, as has been already pointed out by M'Coy and 
 by Billings ; though, of course, one is here confronted with the 
 difficulty that it is open to any one to assert that all specimens 
 in which the mural pores are not biserial are not specimens of 
 F. Gothlandica, but are referable to some distinct species, even 
 though their other characters are identical with those of the for- 
 mer type. I can, for instance, quite corroborate the observation 
 of Mr Billings (loc. cit.) that specimens apparently inseparable 
 from F. Gothlandica in other respects, occur in the Devonian 
 rocks of North America, in which the prismatic faces of the 
 corallites bear sometimes one, sometimes two, and sometimes 
 three rows of corallites, but for the most part two. Such 
 specimens, according to the views of Milne - Edwards and 
 Haime, ought to be separated from F. Gothlandica as a distinct 
 species (F. Goldfussi) ; but it appears to me though it is only 
 with much diffidence that I differ from the views of such justly 
 distinguished authorities that the mere fact of such great varia- 
 tion in a single specimen is strong proof that the character itself 
 is liable to much variation, and is not, therefore, of specific im- 
 portance. With regard to F. basaltica, Goldf., which resembles 
 F. Gothlandica in general features, but is stated to possess 
 uniserial mural pores, I can express no definite opinion, for I 
 have seen no specimens with this character. Unquestionably, 
 if it were shown that there existed a species of Favosites in 
 other respects like F. Gothlandica, but uniformly possessing 
 but a single row of pores on each of the prismatic faces of the 
 corallites, there would be good grounds for regarding this as a 
 distinct species ; but the evidence or want of evidence on 
 this point, would at present rather lead one to believe that 
 
GENERA OF FA VOSITID&. 53 
 
 M'Coy and Lonsdale were right in regarding F. basaltica, 
 Goldf., as a mere variety of F. Gothlandica. 
 
 The tabula in F. Gothlandica are typically " complete " 
 that is to say, they pass completely from one side of the 
 visceral chamber to the other. I am able, however, from 
 specimens in my own possession, to entirely corroborate the 
 statement of Mr Billings (Canad. Journ., new sen, vol. iv. p. 
 1 02, fig. 2) that single examples, otherwise inseparable from 
 this species, exhibit in certain tubes the complete and compara- 
 tively remote tabulae characteristic of F. Gothlandica and its 
 allies ; while in others they show the incomplete, close-set, and 
 interlocking tabulae of F. hemispherica, Yand. and Shumard, in 
 virtue of which this latter was raised by Milne-Edwards and 
 Haime to the rank of a distinct genus (Emmonsia). In type- 
 specimens of F. Gothlandica from the Upper Silurian, there are 
 generally six to eight tabulae in the space of two lines ; but this 
 number may be exceeded, or may not be reached. Ordinarily 
 the tabulae are more or less flat and horizontal, but they are 
 very commonly conspicuously arched upwards, or more rarely 
 concave. The specimens with convex tabulae have usually 
 been separated as a distinct species, under the name of F. 
 favosa, Goldf. ; but a careful examination of a large number of 
 examples has led me to agree with Dr Rominger in thinking 
 that this character is very variable, and that it cannot be relied 
 upon as a specific distinction. Another peculiarity not uncom- 
 monly present is, that the tabulae are bent downwards at their 
 periphery into a series of infundibuliform depressions, giving to 
 the upper surfaces of the diaphragms a plicated or sinuated 
 appearance (PI. I., fig. 4). There are very often twelve of 
 these marginal depressions ; but there may be more or fewer, 
 and they are generally easily to be recognised in thin transverse 
 sections of the corallum (PL I., fig. 2). 
 
 Lastly, the condition of the septa in F. Gothlandica is as 
 variable as that of the other elements of the corallum. In 
 most of the specimens the septa are quite obsolete, or can only 
 be recognised by the practised eye as minute inequalities of the 
 
54 TABULATE CORALS. 
 
 inner surfaces of the walls of the corallites, arranged in vertical 
 series. In other cases, the septa have the form of delicate but 
 unequally distributed spinules, which roughen the interior of 
 the tubes. Finally, there are specimens in which the septa 
 are so far developed as to assume the form of regular radiating 
 spines (PI. I., fig. 5), which may extend nearly to the centre of 
 the visceral chamber, and are usually from twelve to fifteen in 
 number. It is upon examples of this kind that Professor Hall 
 founded his genus Astrocerium; but there can be no doubt that 
 these forms with spiniform septa are simply a varietal condi- 
 tion of this and other species of Favosites. 
 
 Before leaving this species, it may be as well to make a few 
 remarks upon some of the forms which I have included under 
 it. As has been previously said, F. Gothlandica was regarded 
 by Milne-Edwards and Haime as essentially a Silurian species, 
 and the corresponding Devonian forms were separated by them 
 under the name of F. Goldfussi. This latter species is sep- 
 arated by its authors from F. Gothlandica simply upon the 
 ground that its corallites are said to be larger, and that the 
 mural pores are more closely set than in the Silurian form. 
 The size of the tubes (one and a half line) is, however, fre- 
 quently exceeded by typical Upper Silurian examples of F. 
 Gothlandica, and, under any circumstances, cannot be regarded 
 as a character of the smallest specific value, while the mural 
 pores exhibit at least an equal variability. I am therefore 
 quite unable to accept the separation of F. Goldfussi from 
 F. Gothlandica. 
 
 F. favosa of Goldfuss has at first sight more claims for 
 separation from F. Gothlandica, the strong convexity of the 
 tabulae (which led Milne-Edwards and Haime to speak of their 
 possessing a small central columellar eminence) being a very 
 marked feature in some specimens, which otherwise entirely 
 agree with the latter form. The arching of the tabulae is, how- 
 ever, very variable, and one and the same specimen may 
 exhibit both convex and flat tabulae ; so that in the absence 
 of any distinctive character of a more constant nature, I think 
 
GENERA OF FAVOSITID&, 55 
 
 F. favosa, Goldf., must be united with F. Gothlandica, Lam., or 
 at most retained as a distinct variety. 
 
 F. Niagarensis, Hall, from the Niagara group of North 
 America, seems to be certainly founded upon young speci- 
 mens of F. Gothlandica i and it is possible, as Mr Billings 
 thinks, that Astrocerium parasiticum, Hall, and A. pyriforme, 
 Hall, really belong to the same species. Upon this latter 
 point, however, I can offer no opinion. 
 
 Favosites Winchelli, Rominger (loc. cit.}, is founded upon 
 forms from the Corniferous and Hamilton groups (Devonian) 
 of North America, which agree with F. Gothlandica in all 
 general features, but have large tubes (one and a half to two 
 lines in diameter), which are occasionally somewhat rounded, 
 while there are only three or four tabulse in the space of two 
 lines. After examining excellently preserved examples from 
 Canada, I am unable to regard this as more than a varietal 
 form of F. Gothlandica. 
 
 Lastly, the name of F. Billingsii has been given by Dr 
 Rominger to a form of Favosites which occurs commonly in the 
 Hamilton group of Ontario, and which grows in large convex 
 discs, varying from one, two, or three inches up to as many 
 feet in diameter. The cprallum is attached to some foreign 
 body by a point usually placed in the centre of the base, and 
 the entire lower surface is covered by a striated epitheca. 
 The corallites vary from a line to a line and a half in diameter ; 
 and though of the same essentially prismatic or polygonal form 
 as in typical examples of F. Gothlandica, they are slightly less 
 rectilinear and more irregular in shape and size than in the 
 latter (PI. I., fig. 6). Dr Rominger states that the mural pores 
 are uniserial, and they often are so ; but they are just as 
 commonly arranged in two alternating rows, as in F. Gothlan- 
 dica, and the tabulse resemble those of that species. I have 
 figured a transverse section of this form for comparison with 
 the typical F. Gothlandica, and need only say that as examined 
 in this way the trivial difference in the form of the corallites is 
 much more conspicuous than it is .when the calices of the two 
 
5 6 TABULATE CORALS. 
 
 are compared together. To the supposed peculiarities in its 
 mode of growth, I think no weight can be attached, as F. Goth- 
 landica has commonly a similar habit ; and there are no other 
 points of separation worth alluding to. Upon the whole, after 
 minutely examining F. Billingsii, in the ordinary manner and 
 by means of microscopic sections, I cannot consider it as more 
 than varietally distinct from F. Gothlandica, of which it may 
 be regarded as a local variation. 
 
 Formation and Locality?- Upper Silurian (Wenlock Lime- 
 stone), Dudley and Benthall Edge; also near Shalloch Mill, Gir- 
 van. Wenlock Limestone, Gotland. Niagara Group (Wenlock 
 Limestone), Owen's Sound and Manitoulin Island, Ontario. 
 Guelph Formation (Upper Silurian), Cedarville, Ohio. Corni- 
 ferous Limestone (Devonian), Port Colborne, Woodstock, and 
 various other localities in Ontario ; also in the same formation, 
 Phelps, State of New York. Hamilton Formation (Devonian), 
 Erie Co., State of New York, and Arkona, Ontario (var. Bil- 
 lingsii, Rom.) The species is quoted by Milne-Edwards and 
 Haime from the Caradoc sandstone of Britain (Mon. Brit. Foss. 
 Cor., p. 257) ; but I have never seen any example from strata 
 of Lower Silurian age. It is generally regarded as one of the 
 most abundant and characteristic of the Upper Silurian Corals ; 
 but my own experience would, so far as it goes, be in favour of 
 considering F. Forbesi, E. and H., as by far the commoner of 
 the two in the Upper Silurian of Britain, while F. Gothlandica 
 appears to attain its maximum in the Devonian. 
 
 Favosites Forbesi, Edwards and Haime. 
 (PI. L, fig. 7; PI. II., figs. 1-3 j PI. III., figs, i, 2.) 
 Calamopora basaltica (pars), Goldfuss, Petref. Germ., vol. i. p. 78, tab. xxvi., 
 
 figs. 4 a- 4 b, 1829. 
 Favosites Gothlandica, Lonsdale, in Murchison's Silurian System, p. 682, PI. 
 
 XV., bis, figs. 3, 4, 1839. 
 
 Forbesi, Milne - Edwards and Jules Haime, Pol. Foss. des Terr. 
 Pal., p. 238, 1851. 
 
 1 Under this heading I shall, as a rule, only give those localities from which I 
 myself possess specimens. When this rule is departed from, the name of the author 
 on whose authority the reference is gwen will be appended in brackets. 
 
GENERA OF FAVOSITID^E. 57 
 
 Favosites Forbesi, Milne-Edwards and Jules Haime, Brit. Foss. Cor., p. 258, 
 
 PL LX.,figs. 2-2 g, 1854. 
 ,, basaltica (pars), Billings, Canadian Journ., new ser., vol. iv. p. 106, 
 
 1859. 
 Forbesi, Nicholson, Report on the Palaeontology of Ontario, p. 48, 
 
 PI. VII., fig. 8, and PL VIII., fig. 4, 1874. 
 tuberosus, Rominger, Fossil Corals of Michigan, p. 30, PL IX., figs. 
 
 i, 2, 1876. 
 Forbesi (?), Hall, Twenty-eighth Ann. Rep. on the State Cabinet of 
 
 N.Y., PI. IV., figs. 6-15 (not described), 1876. 
 
 Spec. Char. Corallum composite, forming globular, discoidal 
 or clavate masses when young, and becoming when adult more 
 or less irregularly spheroidal, hemispherical, or pyriform in 
 shape, the diameter of the colony varying from less than 
 half an inch up to two, three, or more inches. The colony 
 may be attached to some foreign body by a limited portion 
 of its base, having the whole of the rest of its surface covered 
 by the calices ; or the lower surface may be covered by a con- 
 centrically-striated epitheca, and the calices may be confined to 
 the upper surface only. The corallites are prismatic, often 
 approximating to a cylindrical form, comparatively thick-walled, 
 of more or less conspicuously unequal sizes, the larger and more 
 cylindrical corallites having a variable number of smaller and 
 more angular tubes intercalated among them. The large 
 tubes vary from one to two lines in diameter (being some- 
 times less than one line), and the small tubes have a dia- 
 meter of from one-fiftieth of an inch to half or three-quarters 
 of a line. Mural pores apparently in two or three alternating 
 rows on each prismatic face of the corallites. Septa obsolete, 
 or represented by longer or shorter radiating spines arranged 
 in vertical rows. Tabulae, typically, complete, but sometimes 
 reduced to or accompanied by rudimentary horizontal laminae. 
 
 Obs. F. Forbesi, E. and H., like F. Gothlandica, Lam., is a 
 comprehensive type - form, with well - marked characters, but 
 giving rise to a series of varietal forms, which, from one point 
 of view, may be regarded as distinct species. Regarded in 
 a broad aspect, F. Forbesi is distinguishable from F. Gothlan- 
 dica, Lam., and its immediate allies by the conspicuous in- 
 
5 8 TABULATE CORALS. 
 
 equality of the corallites in point of size, the less markedly 
 prismatic and often nearly cylindrical form of the tubes, and 
 the greater thickness of the walls. In the observations which 
 I have to make upon the structural characters of F. Forbesi, I 
 shall take the form which occurs in the Wenlock Limestone of 
 Britain and Sweden as the type of the species, and I shall con- 
 sider the variations of this type as constituting three distinct 
 varieties viz., var. Waldronensis, Nich., Eifelensis, Nich., and 
 t^lberosa, Rom. It is possible that Calamopora For best, var. 
 discoidea, Roemer (Sil. Fauna of Tenn., p. 19, PI. II., figs. 10- 
 10 b\ is a fourth variety ; but as I possess no examples of this 
 form, I am unable to offer any opinion on this point. 
 
 The normal form of F. Forbesi, E. and H., occurs abundantly 
 in the Wenlock Limestone of Britain, and has been very well 
 illustrated by Milne-Edwards and Haime in their great work 
 on the British Fossil Corals (PI. LX., figs. 2 - 2 g). The most 
 noticeable point about this form is the marked difference be- 
 tween young and old examples in the relative sizes of the 
 corallites supposing, as I think may safely be done, that 
 the specimens in question really represent nothing more than 
 different stages of growth. Young examples (PI. II., fig. i) 
 are discoidal, with an inferior epitheca ; or they form globular 
 masses, which envelop parasitically the stem of a Crinoid or 
 the branch of some dendroid coral, and have their entire 
 free surface covered by the calices. The large-sized calices 
 are both exceptionally numerous and exceptionally large, their 
 diameter varying from a line up to close upon two lines, 
 while the smaller calices are usually from a quarter to half a 
 line in diameter, and are intercalated in comparatively scanty 
 numbers in the limited spaces left between the large corallites. 
 Transverse sections (PI. II., fig. i 6) of such specimens show 
 precisely the same features. On the other hand, full-grown 
 examples have the form of hemispherical, spheroidal, or cla- 
 vate masses, generally two or three inches in diameter, and 
 the inequality of the corallites is much, less marked than in 
 the young state (PI. I., fig. 7). There is a greater proper- 
 
GENERA OF FA VOSITID&. 
 
 59 
 
 tionate number of average corallites ; the small tubes are fewer 
 in number and not so conspicuous ; and the large tubes open 
 on the surface by actually smaller apertures, the diameter of 
 the larger calices being generally about one line, but some- 
 times rather less. Still it would be impossible to confound 
 such examples with specimens of F. Gothlandica, since the 
 observer has no difficulty in at once recognising the presence 
 of a certain number of tubes, which catch the eye in conse- 
 quence of their being larger than the others ; while the pris- 
 matic form of the corallites so characteristic of the latter 
 species is never regularly developed, and the bigger calices 
 have a distinctly circular outline. As regards the internal 
 structure of this form there is little of importance to note. 
 The presence of septa in the form of short spines, vertical 
 striae, or tubercular ridges, can usually be made out by ex- 
 amining the surface with a lens ; and thin transverse sections 
 almost invariably confirm the existence of these structures (PI. 
 I., fig. 7, and PI. II., fig. i b). These septal spines or ridges 
 are, however, always short, and extend but a short distance 
 inwards into the visceral chamber ; nor would they usually be 
 recognised at all by a mere naked-eye examination of the sur- 
 face. Vertical sections (PI. II., fig. i a} show the tabulae to be 
 complete, slender, and slightly flexuous, placed at variable dis- 
 tances apart, six or seven usually occupying the space of two 
 lines. It is specially worthy of note in this connection that 
 Milne- Edwards and Haime have figured an example of this 
 species from the Wenlock Limestone of Wenlock (Brit. Foss. 
 Corals, PL LX., fig. 2/), in which the interior of the tubes is 
 roughened by elevated points or ridges, which, though badly 
 figured, entirely correspond in appearance to the " squamae " 
 which we shall see to be present in F. Forbesi, var. tuberosa, 
 Rom., from the Devonian of North America, and which I 
 believe to be unquestionably the same in their nature. 
 Whether similar rudimentary tabulae are present at all com- 
 monly in the Upper Silurian forms of F. Forbesi, I cannot 
 say ; for these structures very rarely reveal themselves in thin 
 
60 TABULATE CORALS. 
 
 vertical sections, and the British examples of this species, so 
 far as I have seen, very seldom exhibit the interior of the 
 tubes. Finally, for the reason just given, I am not certain 
 as to the arrangement of the mural pores in F. Forbesi ; but 
 in such vertical sections as show these apertures at all, they ap- 
 pear to be biserial or triserial, alternating in contiguous rows, 
 and more closely set than in F. Gothlandica (PI. II., fig. i a). 
 
 Favosites Forbesi, E. and H., var. WALDRONENSIS, Nich. 
 
 (PI. II., figs. 2 - 2 .) 
 
 Favosites Forbesi (1), Hall, Twenty-eighth Rep. on the State Cabinet of N.Y., 
 
 PI. IV., figs. 6-15. 
 
 Corallum forming globular or pyriform masses (PI. II., 2), 
 varying from half an inch up to two inches or more in diameter, 
 and attached by a broad peduncle, the lower part of which may 
 be covered by an epitheca. Large corallites, varying from one 
 and a half to two lines in diameter, and proportionately very 
 numerous, the small corallites occupying the angular spaces 
 between the former, and varying from a fiftieth of an inch to 
 more than half a line in diameter. Septa apparently obsolete 
 (PI. II., 2 a). Tabulae numerous, thin, horizontal, usually about 
 seven in the space of two lines (PI. II., 2 6). 
 
 This well-marked form, from the Niagara Limestone of 
 Waldron, Indiana, quite resembles the common F. Forbesi of 
 the corresponding Wenlock Limestone of Europe in all essen- 
 tial features ; and it would be difficult or impossible to mention 
 any characters by which young specimens of these two forms 
 (up to half an inch or rather more in diameter) could be 
 separated from one another. The chief peculiarity of the 
 present variety lies in the fact that it preserves in its adult 
 condition the distinctions which characterise the young both of 
 itself and of the normal form of F. Forbesi. Hence the fully- 
 grown F. Forbesi, var. Waldronensis, is at once separated by 
 its numerous and exceptionally large corallites, and the com- 
 parative paucity of the small tubes, from the adult F. Forbesi 
 of the British Wenlock, in which the large tubes are much 
 
GENERA OF FAVOSITID^.. 61 
 
 diminished in number, and there is much nearer approach to a 
 general equality in the size of the corallites. This distinction 
 will be at once evident on a comparison of transverse sections 
 of these two forms (PI. I., fig. 7, and PL II., fig. 2 a). 
 
 Favosites Forbesi, van Waldronensis, has been beautifully 
 figured by Professor Hall (loc. cit.}, with a doubtful reference 
 to P. Forbesi, E. and H. ; but, so far as I know, no description 
 of it has been published. In its internal structure there is no 
 feature of special importance to note, save that there seem to 
 be no traces of septal spines, and the tabulae are perhaps more 
 regularly distributed and less flexuous than in the normal form 
 of the species. Professor Hall has figured the tubes with 
 biserial mural pores and so far as I have observed, this is the 
 general arrangement ; but there may be an additional row, and 
 the pores seem to be close-set, and somewhat irregular in their 
 distribution. 
 
 Favosites Forbesi, E. and H., var. EIFELENSIS, Nich. 
 (PL II., fig. 3, and PI. III., figs, i - 1 b.) 
 
 Corallum forming spheroidal or pyriform colonies, from half 
 an inch up to two inches in diameter, but generally an inch or 
 rather more across. Corallites irregularly prismatic, or with 
 rounded angles, and more uniform in size than in typical forms 
 of the species, the larger ones being numerous, but mostly 
 attaining a diameter of no more than a line or three-quarters of 
 a line, while the small tubes are much reduced in numbers. 
 Septa exceptionally well developed, and extending for a con- 
 siderable distance into the interior of the visceral chamber, in 
 the form of strong blunt spines. Tabulae horizontal or slightly 
 flexuous, about six or seven in the space of two lines. Mural 
 pores numerous, close-set, apparently biserial or triserial. 
 
 I propose this name for a small Favosites which I have 
 found to be tolerably plentiful at Gerolstein in the Eifel. Its 
 general appearance (PL III., fig. i) is so closely similar to that 
 of medium-sized specimens of F. Forbesi from the Upper 
 Silurian, that the near relationship of the two forms is beyond 
 
62 TABULATE CORALS. 
 
 doubt. There is also the same general disposition of the cal- 
 ices, there being a marked difference in size between different 
 corallites. In this respect, however, the condition of matters 
 resembles that which obtains in large-sized colonies of the 
 normal F. Forbesi from the Upper Silurian. That is to say, 
 there is an approach to a general equality in size of the tubes, 
 the larger ones not being exceptionally large (mostly from 
 three-quarters of a line to a line in diameter), and being very 
 numerous as compared with the small tubes (PI. III., fig. i a}. 
 The distinguishing peculiarity of this form, however, is the 
 quite unusual development of the septa, which are conspicuously 
 visible even to the unassisted eye, and extend a considerable 
 distance into the cavity of the tubes (PI. II., fig. 3). In long 
 sections (PI. III., fig. i b), the septa are seen to have the form 
 of strong spines, with a broad base, and with a distinct upward 
 inclination. The tabulae resemble those of the normal form of 
 F. Forbesi. The mural pores, as revealed by thin vertical 
 sections, appear to be numerous and close-set, being apparently 
 in two or even in three rows ; but I do not think that much 
 stress can be laid upon this character, especially when only 
 known by the, in this respect, partial and imperfect evidence 
 afforded by transparent longitudinal slices. 
 
 \ 
 Favosites Forbesi, E. and H., van TUBEROSA, Rom. 
 
 (PI. III., figS. 2-2g.) 
 
 Favosites basaltica (pars), Goldfuss, Petref. Germ., PI. XXVI., fig. 4 a (cset. 
 
 exclusis), 1829. 
 basaltica (pars), Billings, Canad. Journ., new sen, vol. iv. p. 106, 
 
 1859. 
 Forbesi, Nicholson, Report on the Palaeontology of Ontario, p. 48, 
 
 PI. VII., fig. 8, and PL VIIL, fig. 4, 1874. 
 ,, tuberosus, Rominger, Fossil Corals of Michigan, p. 30, PI. IX., figs. 
 
 i and 2, 1876. 
 
 Corallum forming cylindrical or club-shaped, rarely hemi- 
 spherical masses, varying from an inch up to half a foot or 
 more in length, according to their age. Corallites conspicu- 
 ously unequal in size, the larger ones being somewhat cylin- 
 
GENERA OF FAVQSITWM. 63 
 
 drical, the prismatic angles of the tubes being obtusely rounded, 
 and varying from a line and a half to a line and three-quarters 
 in diameter. The small tubes are intercalated in the spaces 
 between the smaller ones, and are usually from a quarter to 
 half a line in diameter. Calices often in parts obliterated by 
 an epitheca. Septa represented by blunt tubercular ridges on 
 the inner faces of the walls of the tubes. Tabulae complete, 
 sometimes not developed in a perfect form, but always either 
 represented or accompanied by numerous close-set transverse 
 ridges or lamellae (" squamae "), which are to be regarded as 
 rudimentary tabulae, and which impart a peculiar rough aspect 
 to the inner surfaces of the corallites. 
 
 This form is abundant in the Devonian deposits, and especi- 
 ally in the Corniferous Limestone, of Canada and the United 
 States, and it has a historical interest, as it is unquestionably 
 one of the forms figured by Goldfuss (loc. cit.} under the name 
 of F. basaltica. The specimen figured by Goldfuss is stated 
 in the text to come from Lake Erie ; and the accuracy of the 
 drawing places it beyond a shadow of doubt that it was a 
 silicified example of this form derived from the Corniferous 
 Limestone. Mr Billings, who clearly recognised this fact, 
 appropriated the name of F. basaltica, Goldf., for the form now 
 under consideration, upon the belief that the other forms 
 included by Goldfuss under the same title were really referable 
 to F. Gothlandica, Lam. I have before expressed the opinion 
 that we have not at present sufficient evidence to support this 
 course (Rep. on the Palaeontology of Ontario, p. 48). Those 
 forms included by Goldfuss under F. basaltica, which have 
 prismatic tubes and uniserial mural pores, may turn out ulti- 
 mately to be a variety of F. Gothlandica ; but there is not at 
 present any definite proof of this. I preferred, therefore, and 
 still prefer, to retain the name of F. basaltica, Goldf. if it is to 
 be retained at all for forms which essentially belong to the 
 type of F. Gothlandica, but have the mural pores uniserially 
 arranged. The present form, on the other hand, is clearly of 
 the type of F. Forbesi, E. and H., with conspicuously unequal 
 
64 TABULATE CORALS. 
 
 corallites, and biserial or triserial mural pores; and the only 
 question, to my mind, is as to whether it should be regarded 
 as a variety of this, or as a distinct species. That it belongs 
 to the same type-form cannot be questioned, and I formerly 
 referred it unconditionally to F. Forbesi, E. and H., which was 
 to all practical intents and purposes the course followed by Mr 
 Billings, with this difference, that he regarded F. Forbesi as 
 a mere synonym of F. basaltica, and therefore employed the 
 latter name. Having now made a careful microscopic exam- 
 ination by means of thin sections of both the present form and 
 of typical examples of F. Forbesi, E. and H., from the Upper 
 Silurian, I still think that the two are substantially identical ; 
 but the former presents so many peculiarities, that it may 
 reasonably stand as a distinct variety. For this I have 
 adopted the specific name given to it by Dr Rominger (loc. cit.\ 
 who describes it as a distinct species a view for which I am 
 inclined to think there is as yet hardly sufficient evidence. 
 
 In general shape, the corallum of the present form only 
 differs from that of the typical F. Forbesi, E. and H., in the 
 general predominance of a cylindrical or clavate, rather than a 
 spheroidal figure. I have given a drawing of the youngest 
 and smallest specimen I have seen (PI. III., fig. 2), which gives 
 a very good idea of the general form of the corallum, though 
 adult examples may be six inches or more in length. The 
 characters of the corallites are, also, those distinctive of F. 
 Forbesi (PI. III., fig. 2 a), there being a very marked inequality 
 in the sizes of the tubes, and the larger ones being more or less 
 strikingly cylindrical, rather than strictly prismatic. The large 
 tubes, however, are of comparatively great size, and are com- 
 paratively numerous, while the small tubes are reduced pro- 
 portionately both in size and numbers the condition of things 
 thus rather resembling what we see in the yozmg of the typical 
 Upper Silurian F. Forbesi than in the adult of the same. In 
 calcareous examples from the Hamilton formation of Canada 
 (PI. III., fig. 2 b}, the largest tubes are not so numerous, 
 while the small tubes are increased both in numbers and in 
 
GENERA OF FAVOSITID^E. 65 
 
 size ; though I entertain no doubt as to the identity between 
 these and the silicified specimens from the Corniferous Lime- 
 stone of the same region. As regards internal structure, the 
 walls of the corallites are comparatively thick, and the septa are 
 represented by a number (ten, twelve, or more) of blunt tuber- 
 cular ridges on the inner faces of the tubes (PI. III., fig. 2 c). 
 In silicified specimens, the tabulae generally appear to be 
 wanting (in their ordinary form), or are, at most, present as 
 incomplete transverse partitions ; but vertical sections of cal- 
 careous examples (PI. III., fig. 2 d} exhibit complete hori- 
 zontal or slightly flexuous tabulae of the ordinary type. All 
 the examples of this form, however, have the peculiarity that 
 the interior of the tubes is roughened by a series of close- 
 set projecting transverse ridges or lamellae, which are best 
 seen in silicified examples, in which the corallites are empty 
 (PI. III., fig. 2 e), but which can be recognised in thin vertical 
 sections of calcareous examples as short uneven lines occupy- 
 ing the interspaces between the regular tabulae (PI. III., fig. 
 2 d). These singular and characteristic structures are clearly 
 represented in the specimen of this form from Lake Erie 
 figured by Goldfuss under the name of F. basaltica (Petref. 
 Germ., PL XXVL, fig. 4 a). Mr Billings (loc. /.), while 
 recognising the existence of these lamellae, regards them as 
 possibly merely the result of a peculiar method of fossilisation, 
 but I hardly think that there is any evidence to support this 
 view. Dr Rominger, if I rightly understand his views, regards 
 these projecting lamellae (or " squamae ") as being an abnormal 
 form, or representative of the spiniform septa of so many of the 
 species of Favosites. In this view, for reasons previously given 
 in speaking of the genus, I cannot coincide. The transverse 
 position, and the often complete extension of these lamellae 
 across the whole diameter of a tube, are, in my opinion, fatal 
 to the idea that these structures are in any way of a septal 
 nature ; and I can only regard them as being essentially of the 
 nature of rudimentary tabula. The presence, then, of these 
 imperfect tabulae, is characteristic of the present form ; but I 
 
 E 
 
66 TABULATE CORALS. 
 
 must again draw attention to the fact that Messrs Milne- 
 Edwards and Haime have figured (Brit. Foss. Cor., PL LX., 
 fig. 2/) a specimen of F. Forbesi from the Upper Silurian, in 
 which structures of apparently precisely the same nature seem 
 to be present. Upon the whole, therefore, I do not think that 
 the structures in question can be regarded as of specific value, 
 though they constitute a very striking feature in the Devonian 
 variety now under consideration. 
 
 Of the other characters of the present form, it is only neces- 
 sary to allude to two. In the first place, the mural pores have 
 the character, which seems to be the general rule in the less 
 aberrant types of F. Forbesi, that they are usually biserial, 
 though sometimes triserial. They are more closely set than 
 in F. Gothlandica, and are stated by Dr Rominger to be sur- 
 rounded by a depression instead of an elevated ring. In the 
 second place, many of the calices in the lower part of the coral- 
 lum become covered and completely sealed up by an epithecal 
 or opercular membrane, which can hardly be regarded as the 
 result of mere age, since it seems to be present in extremely 
 young examples (PI. III., fig. 2). It is, however, most con- 
 spicuous in the old specimens, in which a variable number of 
 the corallites are always, or almost always, closed in this way 
 (PI. III., fig. 2 a), those at the summit of the colony remaining 
 open. It must be admitted that this peculiarity has not been 
 observed in any of the Silurian examples of F. Forbesi; but as 
 it occurs in several of the other species of Favosites in the same 
 deposits, I do not think that it can well be regarded as a 
 character of specific importance, being rather the result of local 
 conditions and of environment. 
 
 Formation and Locality. (i.) The typical form of F. Forbesi 
 Wenlock Limestone, Longhope, Dudley, Benthall Edge, and 
 Stoke-Edith ; Wenlock Limestone, Gotland. 
 
 (2.) F. Forbesi, var. Waldronensis Niagara Limestone, 
 Waldron, Indiana, U.S. 
 
 (3.) F. Forbesi, var. Eifelensis Devonian (Eifler-kalk), 
 Gerolstein, Eifel. 
 
GENERA OF FA VOSITID^. 
 
 67 
 
 (4.) F. Forbesi, var. tuberosa Corniferous Limestone, Port 
 Colborne, and other localities in Ontario ; Hamilton group, 
 Arkona, Ontario. 
 
 Favosites (Emmonsia) hemispherica, Yandell and Shumard. 
 (PL III., figs. 3- 3 A) 
 
 Favosites alveolaris, Hall, Geol. of New York, p. 157, No. 13, figs, i and 
 
 i a, 1843. 
 hemispherica, Yandell and Shumard, Contrib. to the Geology of 
 
 Kentucky, p. 7, 1847. 
 Emmonsia hemispherica, Milne - Edwards and Haime, Pol. Foss. des Terr. 
 
 Pal., p. 247, 1851. 
 Favosites hemispherica, Billings, Canad. Journ., new ser., vol. iv. p. 107, figs. 
 
 5-7, 1859. 
 hemispherica, Nicholson, Rep. on the Palaeontology of Ontario, p. 
 
 49, PL VIII., fig. 3, 1874. 
 
 Emmonsii, Rominger, Foss. Corals of Michigan, p. 26, PI. VII., 
 figs, i and 2. (Non Favosites hemisphericus, Rominger, ibid., 
 p. 24.) 
 
 (It has been pointed out to me by my friend Mr George Jennings Hinde, 
 that Mr S. A. Miller, in his ' Catalogue of the American Palaeozoic Fossils,' p. 
 52, states that this species was described by Troost in the 5th Geol. Rep. of 
 Tennessee, in 1840, under the name of Calamopora hemispherica, I have not 
 included this reference in the above list, as I have not access to Troost's work, 
 and have therefore no means of verifying it. Milne-Edwards and Haime do 
 not include Troost in their list of references. If, however, Mr Miller's reference 
 be correct, then Troost's name should follow the species in place of the names 
 of Yandell and Shumard.) 
 
 Spec. Char. Corallum generally hemispherical or irregularly 
 spherical in shape, massive, often 
 several inches in diameter. Coral- 
 lites prismatic, often with round- 
 ed angles, thick-walled, generally 
 about one line or rather less in 
 diameter, but varying from half a 
 line to a line and a quarter. Calices 
 subpolygonal, irregular in size and 
 form, with thick margins. Septa 
 in the form of longer or shorter 
 spines, but often not recognisable. 
 Tabulse most generally in the form of thin, flexuous, close-set 
 
 Fig. 15. Fragment of Favosites hemi- 
 spherica, of the natural size. Devo- 
 nian (Corniferous Limestone), Ontario, 
 Canada. (After Billings.) 
 
68 TABULATE CORALS. 
 
 laminae, which for the most part only extend across about a 
 third or a half of the total diameter of the tube. At other 
 times the tabulae are complete, and they are occasionally quite 
 regular and horizontal. Mural pores usually biserial, very 
 closely set, opposite or alternating. 
 
 Obs. This species was taken by Milne-Edwards and Haime 
 (foe. cit.) as the type of the separate genus Emmonsia, distin- 
 guished from Favosites by the peculiar condition of the tabulae. 
 I agree, however, with Mr Billings in thinking that the occur- 
 rence of single examples of this species in which the tabulae are 
 in parts complete, renders the establishment of a distinct genus 
 for its reception unnecessary. Moreover, incomplete, leaf-like, 
 or squamose tabulae are known to occur in undoubted species 
 of Favosites (e.g., in F. Forbesi and in its variety tuberosd). 
 
 Recently, Dr Rominger (foe. cit.) has applied the name of 
 Favosites hemisphericus, Yand. and Shum., to the entirely dif- 
 ferent F. turbinata of Billings ; while he has established a new 
 species, under the name of F. Emmonsii, for the form now 
 under consideration. The only ground given for this change 
 is, that "all the original specimens of Fav. hemisph. kept in Mr 
 Yandell's collection are identical with Favosites turbinatus of 
 Billings." I regret that, after a careful consideration of the 
 circumstances, and with all deference to this high authority, I 
 am unable to acquiesce in the propriety of this change, where- 
 by two species thoroughly familiar to all palaeontologists are 
 made to change places, one of them receiving an entirely new 
 name. This course deprives Milne-Edwards and Haime on 
 the one hand, and Mr Billings on the other, of their just con- 
 nection with two species which they for the first time described 
 in an excellent and thoroughly recognisable manner; and it does 
 not appear to be sufficiently justified by the fact that the speci- 
 mens labelled F. hemispherica in Mr Yandell's cabinet are really 
 referable to F. turbinata, Billings. On the contrary, it appears 
 to me that the just course in such a case as this, is, not to make 
 any alteration in generally accepted and long current names, 
 unless it can be shown by clear evidence that such an altera- 
 
GENERA OF FA VOSITID^. 6g 
 
 tion is warranted by the published description of the original 
 author, since this is obviously all of which other observers can, 
 as a rule, avail themselves. Taking this view of the question, 
 I quote the entire description of the species given by Yandell 
 and Shumard (Contrib. to the Geol. of Kentucky, p. 7) : 
 
 " Favosites hemispherica. This fossil, the most characteristic 
 of the shell-beds, to which it is limited, is abundant on the Falls, 
 and is found in masses of a hemispherical figure, which vary 
 from one to ten inches in diameter. It is most commonly 
 calcareous, though sometimes it is siliceous." 
 
 Passing over the obvious fact that the above description 
 unaccompanied by any figure is wholly worthless as char- 
 acterising any species of Favosites, and that its vagueness 
 would have altogether justified Milne- Edwards and Haime 
 in giving a new specific title to the form which they were 
 describing, it may be simply remarked that the only two 
 tangible points alluded to by Yandell and Shumard are the 
 shape and the size of the corallum ; and in both these points 
 their description agrees with the Emmonsia hemispherica of 
 Edwards and Haime, and differs from the description of F. 
 turbinata given by Billings. The form of F. turbinata, Bil- 
 lings, though not absolutely uniform, is almost always that 
 of a bent cone, rendering the name turbinata a very apt 
 one ; while of the many examples I have seen, none could 
 be properly said to be "hemispherical," and none exceeds 
 some five or six inches in diameter. On the other hand, 
 Emmonsia hemispherica, E. and H., is typically "hemispheri- 
 cal " in form, and is often eight or ten inches in diameter 
 (Billings gives two or three feet as the maximum diameter 
 of specimens observed by him). Upon the whole, then, I 
 cannot but conclude that the names of F. hemispherica, 
 E. and H., and F. turbinata, Bill., ought to be retained 
 for the forms described by their respective authors under 
 these titles, and that these names should not be invalidated 
 by any evidence which is not based exclusively upon, or 
 directly supported by, published descriptions or figures of 
 
7 o TABULATE CORALS. 
 
 older date these being, in the majority of cases, the only 
 data available to the worker. I have discussed this point 
 at some length, because it seems to me a matter of import- 
 ance that every observer should receive due credit for his 
 labour, and that the principle involved is one of some 
 concern to all palaeontologists and zoologists; and I am 
 happy to know that in this special case I have the entire 
 concurrence of my friend Mr George J. Hinde, whose wide 
 acquaintance with the American Palaeozoic Corals generally, 
 and with these forms in particular, renders his opinion on 
 such a question of peculiar value. I need hardly add that 
 I do not suppose for one moment that Dr Rominger has 
 intentionally done an injustice to his predecessors, and I 
 trust that a reconsideration of all the facts of the case will 
 induce him to alter his decision on this point. 
 
 In its general form and habit, F. hemispherica, Yand. and 
 Shum., is of the type of F. Gothlandica, Lam., its corallum being 
 massive, and its corallites essentially polygonal. The prismatic 
 shape of the tubes is, however, not so conspicuous as in the 
 latter species, partly because the angles of the prisms really are 
 often obtusely rounded, and partly because the walls of the 
 corallites are much thicker (PI. III., fig. 3). Without having the 
 obvious intermixture of large and small tubes which character- 
 ises F. Forbesi, E. and H., there is a considerable want of 
 uniformity in the size of the corallites, and it is not unusual for 
 particular parts of the corallum to be occupied by tubes of less 
 than the average dimensions, while in other parts the average 
 diameter is maintained or exceeded. Upon the whole, the 
 majority of the corallites are from three-quarters of a line to a 
 line in diameter, the latter measurement being only rarely ex- 
 ceeded. I formerly included under this name (loc. cit^ colonies 
 in which the tubes have an average diameter of from half a line 
 
 o 
 
 to three-quarters of a line ; but I feel doubt as to whether these 
 really belong to this species, as I have not been able to exa- 
 mine their internal structure fully. Septa are present in the 
 form of irregular spines, which can be observed in specimens 
 
GENERA OF FAVOSITIDJZ. 71 
 
 in which the tubes are empty, or in transverse sections (PI. 
 III., fig. 3), but which can be with difficulty separated from 
 the imperfect tabulae. The mural pores are most generally 
 biserial, sometimes triserial, and are remarkable for their close 
 arrangement. In the best - preserved calcareous examples 
 which have come under my notice, they form a double row, 
 running down the centre of each prismatic face (PI. III., fig. 
 3 a), sometimes alternately, sometimes oppositely placed, con- 
 tiguous pores in each row being separated by their own 
 diameter or less. The most remarkable feature about the 
 present species, however, is presented by the tabulce, which 
 can be admirably studied by means of specimens from the 
 Corniferous Limestone of Wainfleet, Ontario, in which the 
 corallum is in the exceptional condition of not only being 
 calcareous, but of being entirely empty and free from foreign 
 matter, thus quite resembling the skeleton of a recent coral. 
 In such specimens it is not unusual to find that the condition 
 of parts is twofold. In some of the tubes, sometimes in the 
 greater number, the corallites are traversed by horizontal and 
 complete tabulae, about five of which occupy the space of two 
 lines, the state of matters in these corallites thus resembling 
 what we see in F. Gothlandica, Lam. In other tubes, again, 
 there are few or no complete tabulae, but the visceral chamber 
 is crossed by a series of incomplete tabulae, in the form of thin 
 foliaceous, irregularly flexuous laminae (PI. III., fig. 3 b), which 
 only extend to a certain distance inwards towards the axis of 
 the tube, and are often so closely packed as to cause a regular 
 interlocking of their free ends, or even an actual anastomosis 
 or confluence. When viewed from above, these incomplete 
 tabulae often have a regularly radiate arrangement, and thus 
 simulate septa ; but their true nature is rendered obvious by 
 their broad, leaf-like, or tongue-like form, and by their trans- 
 verse extension as regards the axis of the visceral chamber. 
 While many specimens, as just remarked, show a development 
 of complete tabulae in some tubes and of incomplete ones in 
 others, it should be remarked that in other examples, often of 
 
7 2 TABULATE CORALS. 
 
 very large size, all the tubes exhibit the characteristic incom- 
 plete and inosculating tabulae of this species. 
 
 Formation and Locality. Common in the Corniferous Lime- 
 stone (Devonian) of Rama's Farm, Port Colborne, and other 
 localities in the same formation in Ontario. The species 
 occurs at many points in the United States, where the 
 Corniferous Limestone is exposed ; and it is quoted by 
 Milne-Edwards and Haime from the Upper Silurian of the 
 same area. 
 
 Favosites Bowerbanki, Milne-Edwards and Haime, sp. 
 (PI. III. figs. 4- 4 A) 
 
 Favosites spongites (pars), Lonsdale, in Murchison's Silurian System, p. 6^3, PI. 
 
 XV., bis, figs. 8 c-8 e (cset. exclusis), 1839. 
 Chatetes (?) Bowerbanki, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal, 
 
 p. 272, 1851. 
 Monticulipora (?) Bowerbanki, Milne-Edwards and Haime, Brit. Foss. Cor., p. 
 
 268, PI. LXIIL, figs, i - 1 f, 1854. 
 
 Spec. Char. Corallum exceedingly variable in form and size, 
 but generally in the shape of thick lobate and branched masses. 
 Corallites irregularly polygonal in shape, mostly about one-fif- 
 tieth of an inch in diameter, but sometimes less or more ; the 
 walls thin, and perforated by irregularly-distributed mural pores, 
 which vary in number in different examples, and may be uni- 
 serial, biserial, or triserial. Calices irregularly polygonal, occa- 
 sionally diamond-shaped in parts of the corallum, often divided 
 by incomplete vertical partitions arising from both sides of the 
 wall, and indicating unfinished fission of the tube. Septa en- 
 tirely obsolete. Tabulae very few in number, usually curved, 
 remote, from three-quarters of a line to a line apart. 
 
 Obs. I have not thought it necessary to figure a specimen 
 of this species, as it has been very well illustrated by Milne- 
 Edwards and Haime (Brit. Foss. Cor., PI. LXIIL) The 
 principal figure given by these authors is, however, that of 
 a quite exceptionally complex and dendroid example of this 
 form. So far as I have seen, the corallum is generally in the 
 
GENERA OF FA VOSITIDJE.. 73 
 
 form of lobate pyriform masses, which, when young, are from an 
 inch to two inches in height, with a diameter of half an inch to 
 an inch. Sometimes they terminate above in a simply dilated 
 and undivided upper surface, which may be slightly convex or 
 nearly flat ; but at other times they split up superiorly into two 
 or more lobate divisions. Older examples, with or without 
 proportionate increase in height, may become massive, till we 
 get coralla, of variable, but most generally of obconical shape, 
 which may be three or four inches in diameter at their summit. 
 While branching of the corallum is quite common, I have not 
 personally met with so completely dendroid a specimen as one 
 of those figured by Edwards and Haime (Brit. Foss. Corals, 
 PI. LXIIL, fig. i). The lower and outer surface of the coral- 
 lum does not appear to be covered with a regular epitheca at 
 least I have not observed such a structure ; but the long irreg- 
 ularly prismatic corallites pass upwards from the base of at- 
 tachment, diverging as they go in such a manner that a side 
 view exhibits the walls of the corallites, broken at tolerably 
 regular intervals by recurrent spaces or ledges occupied by 
 open calices. This feature is one very characteristic of the 
 pyriform examples of this species, but in all forms alike the 
 uppermost surface is occupied by the calices. 
 
 Milne-Edwards and Haime referred this species with doubt 
 to Chcetetes or Monticulipora, and of its close resemblance to 
 these genera there can be no question. Vertical sections, suit- 
 able for microscopic examination, bring into view, however, a 
 well-developed series of mural pores, and thus prove conclu- 
 sively that the species is truly referable to Favosites (PI. III., 
 fig. 4 b\ The pores are irregularly distributed, and seem to be 
 generally in two or three series, their size always being small. 
 They are very abundant and conspicuous in Swedish examples, 
 and, for some reason, appear to be much fewer in number in 
 British specimens, though still quite determinable with a little 
 care. It is worthy of note, in this connection, that though the 
 existence of mural pores can usually be recognised in thin 
 sections without any difficulty, I have never succeeded in de- 
 
74 TABULATE CORALS. 
 
 tecting the smallest sign of these apertures by an examination 
 of the outsides of the tube with a hand-lens, though I have for 
 this purpose carefully gone over an extensive series of excel- 
 lently preserved specimens. This shows that the mere fact 
 that mural pores cannot be detected with a magnifying-glass, 
 even in calcareous examples, is not proof positive that such 
 openings are absolutely wanting. 
 
 The corallites of F. Bowerbanki are long and slender, of 
 variable size, but usually from one-sixth to one-quarter of a 
 line in diameter. Their cross-sections (as the calices also) are 
 irregularly polygonal (PI. III., fig. 4), and in their general 
 aspect they closely resemble the corallites of Cluetetes radians, 
 Fischer, and its allies. They show a peculiarity, also, which is 
 very characteristic of the forms just alluded to (such as Chcetetes 
 septosus, Flem.) viz., that the larger tubes are not uncom- 
 monly partially subdivided by vertical partitions, which spring 
 from the wall, and extend a certain distance inwards into the 
 interior of the visceral chamber (PI. III., figs. 4, 4 a). These 
 incomplete partitions are usually placed in pairs, one opposite 
 the other, and they appear ultimately to become complete by 
 the union of their inner ends. Though they might be taken at 
 first sight as irregular septa, they really are not of this nature, 
 and they truly indicate different stages in the multiplication of 
 the older corallites by means of fission. Genuine septa, in the 
 form of vertical ridges, tubercles, or spines, such as are so com- 
 monly present in other species of Favosites, seem here to be 
 entirely absent. Lastly, the tabulse are present in the form of 
 slender curved plates, which are exceptionally few in number 
 and remote in position (PI. III., fig. 4 d), not more than two or 
 three of these structures usually occupying the space of two 
 lines. 
 
 Formation and Locality. Abundant in the Wenlock Lime- 
 stone of Benthall Edge, Stoke-Edith, and Longhope. Also in 
 the Wenlock Limestone of Gotland. 
 
GENERA OF FA VOSITID&. 75 
 
 Favosites clausa, Rominger. 
 
 (PL IV., figs, i- 1 c.) 
 Favosites clausus, Rominger, Fossil Corals of Michigan, p. 36, PL XIV., 1876. 
 
 Spec. Char. Corallum dendroid, of branching or anastomos- 
 ing, cylindrical or oval stems, from two to five lines in diameter, 
 attached by its base, but having its whole free surface covered 
 by the calices, Calices open only in parts of the surface, and 
 especially towards the ends of the branches, but elsewhere 
 closed by flat or convex opercula. Corallites unequal in size, 
 the larger ones being conspicuously circular or oval in shape, 
 and about half a line in diameter, while the smaller ones are 
 more or less angular in form, and vary from a fifth to a third 
 of a line in diameter. Surface commonly marked by raised 
 encircling ridges, which usually have a spiral direction, and are 
 placed parallel with one another at intervals of from half a line 
 to a line or more. These are simply formed by the elevation 
 of the lips of a number of the calices along a given line, and they 
 appear to mark successive stages of growth. Septa obsolete ; 
 tabulae complete, horizontal, or slightly bent, from three to 
 four in the space of one line, sometimes with a few incomplete 
 tabulse interspersed among the others. Mural pores uniserial. 
 
 Obs. This pretty little species may be regarded as a good 
 example of a true Favosites (as distinguished from Pachypora, 
 Lindst), growing in a branching and dendroid form. The 
 inequality of the calices and the markedly circular shape of 
 the larger tubes (PI. IV., fig. i d} are characters in which the 
 species makes a distinct approach to Fistulipora, M'Coy ; but 
 F. Forbesi, E. and H., exhibits the same feature to a less 
 marked extent ; and the presence of mural pores sufficiently 
 separates the present form from the species of the latter genus. 
 It is also separated from Pachypora by the fact that the walls of 
 the corallites show none of that thickening in the neighbour- 
 hood of their mouths which is so characteristic of the latter. 
 The existence of an operculum in the form of a flat or convex 
 
76 TABULATE CORALS. 
 
 calcareous plate in a large number of the calices is a peculiar 
 feature in the species (PI. IV., fig. i a) ; but the same character 
 occurs generally in F. Forbesi, var. tuber osa, Rom., and con- 
 stantly in F. turbinata, Bill. In all these forms the actual 
 characters of the operculum are the same, but in the last- 
 mentioned species they become more or less continuous, so as 
 to constitute a regular epithecal membrane, clothing the entire 
 under surface of the corallum. Thin tangential sections ex- 
 hibit no traces of septal ridges or tubercles. Similar vertical 
 sections show that the walls of the corallites are not thickened 
 as they approach the surface, and that the visceral chamber of 
 each tube is crossed by delicate horizontal tabulae, which are 
 usually complete, though occasionally incomplete ones exist as 
 well. Rominger says that the mural pores are "numerous." 
 So far as I have observed them in thin sections, they are uni- 
 serial, and moderately close to one another. 
 
 Formation and Locality. Hamilton Group (Devonian), 
 Arkona, Ontario, and Erie County, N.Y. (Dr Rominger 
 states that it occurs also in the Corniferous Limestone.) 
 
77 
 
 CHAPTER IV. 
 
 GENERA OF FAVOSITID/E (continued]. 
 
 Genus PACHYPORA, Lindstrom, 1873. 
 (Ofversigt af K. Vetensk. Akad. Forhandl.) 
 
 Gen. Char. Corallum dendroid or frondescent, of polygonal 
 or subcylindrical corallites, the walls of which are greatly 
 thickened towards their mouths by the deposition of concentric 
 layers of sclerenchyma. Calices sometimes annular, some- 
 times oblique and semi-lunar. Septa in the form of minute 
 spiniform projections, or obsolete. Tabulae complete, remote. 
 Mural pores few in number, irregular, often of large size. 
 
 This genus was founded by Lindstrom for the reception of 
 the single species Pachypora lamellicornis, Lindst, from the 
 Upper Silurian deposits of Gotland, which will be shortly 
 described immediately. So far as my investigations have 
 gone, the genus will be found to include a considerable number 
 of types, some of which have been referred to Favosites, while 
 others have been placed in Alveolites. Thus it has been 
 already pointed out by Mr R. Etheridge, jun., and myself 
 (Journ. Linn. Soc., vol. xiii. p. 362), that the so-called Alveo- 
 lites Fischeri) Bill., and Alveolites frondosa, Nich., of the 
 Devonian deposits of North America, are really referable 
 to Pachypora; and I have now determined that the well- 
 known Favosites cristata, E. and H., of the Upper Silurian, 
 and F. cervicornis, De Blainv., of the Devonian, must be 
 placed in the same genus. It is probable, in fact, that all the 
 
78 TABULATE CORALS. 
 
 thick-walled species which have been regarded as dendroid 
 forms of Favosites will more appropriately find a place in 
 Pachypora; and the same may be considered as likely as 
 regards the majority of the thick - walled types which have 
 been referred to Alveolites. 
 
 The mere thickening of the walls would not of itself afford a 
 sufficient ground for the separation of Pachypora as a generic 
 division, since it is present in other groups ; but there are other 
 distinctive characters to be taken into account as well. Little 
 stress can be laid upon the external form of the corallum, but 
 all the known species are dendroid or frondescent. P. lamelli- 
 cornis, Lindst, the type-species, forms flattened branches, which 
 are often coalescent ; P. Fisckeri, Bill, and P.frondosa, Nich., 
 grow as broad undulating expansions or fronds ; P. cristata, E. 
 and H., and P. cervicornis, De Blainv., are essentially ramose, 
 usually with cylindrical branches, but sometimes sublobate. 
 In all these cases the corallum is fixed to some foreign body 
 by its base ; and there is no epitheca, the whole of the free 
 surface being covered by the open mouths of the corallites. 
 The calices are sometimes circular, sometimes polygonal, some- 
 times markedly triangular; so that the genus includes forms 
 which would, in this respect, fall on the one hand under Favo- 
 sites, and on the other hand under Alveolites. The calices are 
 in all instances more or less remote from one another, and 
 thin sections show that the cause of this remoteness is to be 
 found in the thickening of the walls of the corallites by a 
 secondary deposit of sclerenchyma. This thickening affects 
 the corallites throughout their entire length, but it is least 
 developed in the central and interior portion of the corallum, 
 and becomes much more conspicuous as the mouths of the 
 tubes are approached. Hence in tangential sections taken 
 close to the surface the visceral chamber is seen to be sur- 
 rounded by a dense calcareous envelope composed of numer- 
 ous delicate concentric laminae, and surrounded externally by 
 a clearly distinguishable proper "wall" (see PL IV., figs. 2 a and 
 3 c}. The tabulae are poorly developed, being few in number, 
 
GENERA OF FA VOSITIDJE. 79 
 
 remote, and in general complete. P. cristata, E. and H., how- 
 ever, sometimes exhibits structures which may possibly be 
 incomplete tabulae. Septa are usually recognisable, as minute 
 tubercles or spines, but may be wholly obsolete. Lastly, the 
 mural pores differ from those of the typical forms of Favosites 
 in being comparatively few in number, apparently arranged in 
 no regular series, and usually of large size. 
 
 From Favosites proper, Pachypora is to be distinguished 
 principally by the thickening of the walls of the corallites, the 
 characters of the mural pores and tabulae, just alluded to, 
 affording secondary points of difference. From Alveolites, as 
 I shall here define it, the genus must likewise be separated 
 chiefly by its incrassated walls. Striatopora, Hall, is very 
 nearly allied to Pachypora, but may be separated by the fact 
 that the cup of the calice is constricted at its base, and the 
 walls below this point are excessively thickened. Trachypora 
 E. and H., is another allied type ; but in it the thickening of 
 the walls of the corallites attains its maximum, and tabulae are 
 greatly reduced or wanting. 
 
 The only other point which need be noticed is the relation 
 between Pachypora, Lindst., and Cladopora, Hall. The latter 
 genus was originally founded by Hall (Pal. N.Y., vol. ii. p. 
 137), for branching or reticulate corals from the Niagara 
 Group, " composed of a series of tubes or cells radiating 
 equally on all sides from the axis, and opening upon the 
 surface in rounded or subangular expanded mouths." The 
 corallites are stated to be more or less closely arranged, but 
 not always contiguous, and both tabulae and septa are said to 
 be apparently absent. On the other hand, in the latest defini- 
 tion of Cladopora, Hall, as given by Rominger (Foss. Cor. of 
 Michigan, p. 45), the genus is placed among the Favositidcz, 
 and is stated to possess mural pores, with " occasionally " 
 tabulae. There can, further, be no doubt but that the Corals 
 placed by Dr Rominger under this head are in great part 
 referable to Pachypora, Lindst. ; and as Cladopora, Hall, is of 
 course a much older name, it might seem proper to suppress 
 
80 TABULATE CORALS. 
 
 the former in favour of the latter. It is not clear, however, 
 that any of the forms originally included by Hall (loc. cit.) under 
 the name Cladopora are really congeneric with Pachypora 
 lamellicornis, Lindst. ; while it is certain that many of the 
 forms which have subsequently been placed under Cladopora 
 by American palaeontologists are of very diverse affinities. 
 Moreover, Dr Rominger states that septa are not developed in 
 the forms which he calls Cladopora, these structures being un- 
 doubtedly present in the typical forms of Pachypora, Lindst. 
 Under these circumstances, therefore, I have not thought it 
 advisable to resuscitate the genus Cladopora, though it is quite 
 possible that one or more of the forms originally described 
 under this name by Hall are really identical in their characters 
 and structure with the more recently described Pachypora 
 of Lindstrom. 
 
 So far as certainly known, the species of Pachypora are con- 
 fined to the Upper Silurian and Devonian deposits. 
 
 Pachypora lamellicornis, Lindstrom. 
 (PI. IV., figs 2-2 c.) 
 
 Pachypora lameUicornis, Lindstrom, Nagra anteckningar om Anthozoa Tabu- 
 
 lata. Ofversigt af Kongl. Vetensk. Akad. Forhandl., 1873. 
 lamellicornis, Nicholson and R. Etheridge, jun., Journ. Linn. Soc., 
 vol. xiii. p. 361, PL XX., figs. 15-17. 
 
 Spec. Char. Corallum composed of broad flattened branches 
 having a width of from four to seven lines or more, with a 
 thickness of from two to three lines, often coalescing to form 
 flat reticulate or palmate expansions (PL IV., fig. 2). Corallites 
 essentially polygonal in shape, tolerably equal in size, from one- 
 third of a line to two-fifths of a line or rather more in diameter. 
 Walls of the corallites greatly thickened by a secondary 
 deposit of sclerenchyma, which is laid down in delicate con- 
 centric laminae in the interior of the tubes, and increases 
 considerably in amount as the mouth is approached (PI. IV., 
 figs. 2 a and 20}. Calices covering the entire free surface of 
 
GENERA OF FAVOSITID^E. 81 
 
 the corallum, subpolygonal, rounded, or sometimes distinctly 
 oblique and semicircular, the margins being thick, and the 
 lower lip not specially prominent. Septa represented by minute 
 tubercles or spines, arranged in vertical rows (PI. IV., fig. 2 a). 
 Tabulae delicate, few in number, remote, and complete (PI. IV., 
 fig. 2 b). Mural pores few, irregular, of comparatively large size. 
 
 Obs. Dr Lindstrom has kindly furnished me with speci- 
 mens of this, the type-species of the genus Pachypora, from 
 which I have been enabled to draw up the above description. 
 As the structure and affinities of the genus have already been 
 discussed at some length, it is unnecessary here to enter into 
 further details as to the characters of this interesting form. 
 In its general appearance it resembles most nearly a palmate 
 or dendroid Favosites; but the conspicuous thickening of the 
 mouths of the calices, and the consequent remoteness of these 
 apertures, is sufficient to separate it from the typical forms of the 
 latter. Sometimes the calices resemble those of Favosites in 
 being polygonal or rounded, sometimes they are like those of 
 Alveolites in being markedly oblique and semi-lunar; and both 
 these conditions are commonly present in the same specimen, 
 calices of the latter shape occurring principally towards the 
 ends of the branches. The lower lip of the calice is, however, 
 never markedly prominent, nor thinner than the rest of the cali- 
 cine margin. The nearest ally to P. lamellicornis is the P. 
 (Alveolites) Fischeri, Bill., of the Devonian of North America ; 
 but the corallum of the latter is invariably in the form of thin 
 lamellar or palmate expansions, never partially or completely 
 ramose, while the calices are commonly oblique and subtri- 
 angular over the whole surface. There is also a close resem- 
 blance between the present species and P. (Favosites) cristata, 
 E. and H., from the Upper Silurian of Britain ; but the latter 
 is always distinctly ramose, of more or less cylindrical branches, 
 while its tabulae are much more largely developed, and the 
 septa appear to be nearly obsolete. 
 
 Formation and Locality. Upper Silurian (Wenlock Lime- 
 stone), Wisby, Gotland. (Coll. Dr Gustav Lindstrom.) 
 
82 TABULATE CORALS. 
 
 Pachypora cervicornis, De Blainville, sp. 
 (PL IV., figs. 3-3 rf.) 
 
 Calamopora polymorpha, var. ramoso-divaricata, Goldfuss, Petref. Germ. t. i. 
 
 PI. XXVIL, figs. 3 a, 40, 4^, 4<r(ceet. exclusis), 1826. 
 spongites, var. ramosa, Goldfuss, ibid., PL XXVIII., figs. 2a-2g 
 
 (caet. exclusis), 1826. 
 Alveolites cervicornis, De Blainville, Diet. Sci. Nat, t. Ix. p. 369, 1830. 
 
 reticulata, De Blainville, ibid., p. 369; 1830. 
 Favosites cronigera, Alveolites celleporatus, and Alveolites spongites, D'Orbigny, 
 
 Prodr. de Paleont., t. i. pp. 107, 108, 1850. 
 
 cervicornis, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 p. 243, 1851; and Brit. Foss. Cor., p. 215, PI. XLVIIL, fig. 2 (?), 
 
 1853- 
 
 reticulata, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 p. 241, and Brit. Foss. Cor., p. 215, PL XLVIIL, figs, i-i b, 
 
 1853- 
 polymorpha, Billings (pars), Canad. Journ., new ser., vol. iv. p. in, 
 
 fig. n, 1859. (N on Goldfuss.) 
 reticulata, Nicholson, Rep. on the Pal. of Ontario, p. 51, PL VIL, 
 
 fig. 2, 1874. 
 dubia, Nicholson (pars), ibid., p. 51, PL VIL, fig. 5, 1874. (Non 
 
 Favosites cervicornis, Nicholson, ibid., p. 52.) 
 limitaris, Rominger(?), Foss. Cor. of Michigan, p. 35, PL XIII. 
 
 Spec. Char. Corallum of branching cylindrical stems, which 
 vary in diameter from two up to ten lines, and which some- 
 times inosculate so as to form reticulated expansions. Coral- 
 lites essentially polygonal, but having the visceral chamber 
 greatly narrowed by a secondary deposit of sclerenchyma, 
 which increases in amount towards the mouth. Calices sub- 
 polygonal, with thickened lips surrounding a subcircular aper- 
 ture, tolerably equal in point of size, and usually about half a 
 line in diameter, more or less. Septa obsolete, or represented 
 only by very minute spiniform tubercles. Tabulae comparatively 
 few in number (in some cases apparently numerous), complete, 
 horizontal or slightly flexuous. Mural pores few, large-sized, 
 irregularly distributed. 
 
 Obs. The dendroid Favositoid Corals constitute a group 
 particularly difficult to study and to separate satisfactorily into 
 species, and with the space at my command it would be use- 
 
GENERA OF FAVOSITIDsE. 83 
 
 less to attempt to discuss and illustrate more than one or two 
 types. Some forms, as has been seen, have the thin walls 
 of Favosites proper, and are clearly generically inseparable from 
 the more typical massive examples of this group. The forms 
 now under consideration, however, have the thickened walls 
 and general structural characters of Pachypora, Lindstrom, 
 under which head they ought clearly to be placed. The 
 species which I have here selected is one highly characteristic 
 of the Devonian, and I have made a careful macroscopic and 
 microscopic study of a large number of specimens which I have 
 personally collected from rocks of this age in Devonshire, in 
 the Eifel, and in Canada. Nevertheless I do not feel certain 
 as to the limits of the species, nor am I sure that all the forms 
 given in the foregoing list of synonyms are really only varia- 
 tions of a common specific type, though I am disposed at 
 present to take this view. 
 
 The figures which I have given (PI. IV., figs. 3 - 3 c) are all 
 taken from a single form, which I found to be very abundant 
 at Gerolstein, in the Eifel, and which I consider as certainly 
 identical with those figured from the same region by Goldfuss 
 under the name of Calamopora polymorpha, var. ramoso-digitata 
 these being identified by the high authority of MM. Milne- 
 Edwards and Haime with the Alveolites cervicornis of De 
 Blainville. Nor can I doubt the substantial identity of this 
 form with the Favosites reticulata of De Blainville, the only 
 tangible difference between them being the unimportant feature 
 that the branches of the latter inosculate with one another. 
 On the other hand, Milne-Edwards and Haime, in the ' Poly- 
 piers Fossiles,' state that the larger calices of F. cervicornis have 
 a diameter of nearly two millimeters, and that the walls are 
 only " un peu epaisses ; " whereas they give one millimeter as 
 the diameter of the calices in F. reticulata, and speak more 
 decisively as to the thickness of the walls of its corallites. 
 Goldfuss's figures, however, which are usually very reliable, 
 show hardly any appreciable difference in the size of the coral- 
 lites in these two forms, both having the majority of the calices 
 
84 TABULATE CORALS. 
 
 about one millimeter in diameter, and thus agreeing with the 
 examples which I have seen from the Eifel. The statements 
 on this head made by Milne-Edwards and Haime would much 
 more closely apply to the form which they have described and 
 figured from the Devonian rocks of Devonshire under the 
 
 o 
 
 name of F. cervicornis (Brit. Foss. Cor., PI. XLVIII., fig. 2), 
 and which is so common in the limestones of Newton-Bushell 
 and Torquay. This form has large calices which are often 
 nearly two millimeters in diameter, and the thickening of its 
 walls (though present) is not strikingly marked. I am, how- 
 ever, very much disposed to doubt if this be specifically iden- 
 tical with the form figured by Goldfuss from the Eifel, and 
 my opinion is based both upon actual specimens and upon 
 thin sections. The Devonshire form is rather sublobate than 
 strictly dendroid ; its walls are not nearly so thick as those of 
 the typical examples from the Eifel ; its calices are on an aver- 
 age larger ; and its tabulse are much more numerous and more 
 closely set. Upon these grounds, though I have doubtfully 
 placed it under this species, I am inclined to think that it is 
 entitled to at least varietal if not specific distinction. The form 
 figured by Billings, from the Corniferous Limestone of Canada, 
 as F. cervicornis (Canad. Journ., new ser., vol. iv. p. no, fig. 
 9), and subsequently described by me under the same name 
 (Rep. on the Pal. of Ontario, p. 52, 1874), is apparently identi- 
 cal with, or closely allied to, the Devonshire form, and differs 
 from the Eifel specimens in the characters above alluded to as 
 distinctive of the British examples. 
 
 Favosites polymorpha, Goldfuss, has often been regarded as 
 comprising dendroid forms, probably in part identical with the 
 present type. It seems clear, however, that this name, if it be 
 retained at all, can only be with propriety kept for examples of 
 a submassive or completely massive form, with uniserial pores, 
 and with the thin walls characteristic of Favosites proper. 
 
 Favosites dubia, De Blainv., again, comprises dendroid species 
 which are obviously of the Pachypora type, and it is a question 
 whether the species can be maintained as distinct from Pachy- 
 
GENERA OF FAVOSITIDJZ. 85 
 
 pora (Favosites) cervicornis. The presence of very minute 
 calices scattered among the larger ones is of itself, perhaps, 
 hardly of more than varietal value ; but if Goldfuss's figure can 
 be trusted (Calamopora polymorpha, var. gracilis, Petref. Germ., 
 PI. XXVII., fig. 5), then Pachypora (Favosites) dubia is suffi- 
 ciently distinguished from P. cervicornis by the comparatively 
 large size and the obliquity of its calices. 
 
 Lastly, it seems very probable that some of the forms figured 
 by Rominger (Fossil Corals of Michigan) are really inseparable 
 from the present species ; and this is specially the case with F. 
 limitaris, Rom., in part or in whole. From an examination of 
 numerous specimens of this form from the Corniferous Lime- 
 stone of Ontario, I can assert its very close resemblance to ex- 
 amples of P. cervicornis from the Eifel this resemblance in 
 some cases amounting to absolute identity of external char- 
 acters. Other specimens, again, have larger and more dis- 
 tinctly circular or annular calices, thus closely approximating to 
 the type of Pachypora (Favosites) dubia, De Blainv. Unfortu- 
 nately, the highly silicified state of the Canadian specimens, 
 accompanied with a more or less completely hollow condition 
 of the tubes of the corallites, renders it impossible to prepare 
 satisfactory microscopic sections ; and in the absence of these, 
 I hesitate to pronounce as to their absolute identity with 
 the European type, though I cannot doubt their very close 
 alliance. 
 
 Taking the Eifel specimens as the type of Pachypora cervi- 
 cornis, De Blainv., the corallum is generally in the form of cy- 
 lindrical or subcylindrical, often irregularly swollen branches, 
 from two to ten lines in diameter (PI. IV., fig. 3), dividing at 
 variable intervals, but usually not anastomosing. Where inos- 
 culation of the branches occurs, it may perhaps be convenient 
 to use De Blainville's name of reticulata as a varietal designa- 
 tion, though forms so characterised certainly differ in no other 
 particular from those which divide without anastomosis. The 
 corallites radiate from the axis of the branch, curving gently 
 outwards till they open on the surface, and their true form is 
 
86 TABULATE CORALS. 
 
 essentially polygonal. This is clearly shown by sections at 
 right angles to their course, and especially by those which 
 cut perpendicularly across their axial portions (PL IV., fig. 3 c). 
 The walls of the corallites, under all circumstances, remain quite 
 distinctly recognisable in thin sections, but the visceral chamber 
 becomes more and more contracted as we approach the mouths 
 of the tubes, by a dense secondary deposit of sclerenchyma (PI. 
 IV., figs. 3 b, 3 c). As the result of this thickening of the 
 walls, the calices assume the form of rounded apertures encircled 
 by a prominent thickened margin (PI. IV., fig. 3 a), the true 
 wall being still discernible as a raised thread-like line describ- 
 ing a polygon round the central opening. In transverse or 
 tangential sections (PL IV., figs. 3 b, 3 c), the visceral chamber 
 is seen to be reduced to a comparatively small circular or oval 
 tube; and in longitudinal sections (PL IV., fig. 3 d) the same 
 feature is shown, while it is seen that the secondary deposit of 
 sclerenchyma is laid down irregularly, so as to constrict the 
 visceral chamber unequally at different points, but always most 
 markedly towards the mouth. Vertical sections also show that 
 the tubes are crossed by a few comparatively remote, complete, 
 and approximately horizontal tabulse, and that the walls are 
 pierced by a few larged-sized and irregularly placed mural 
 pores. In many instances, transverse or tangential sections 
 coincide in places with the plane of a mural pore, and then 
 the visceral chambers of contiguous corallites are shown as 
 laterally continuous (PI. IV., fig. 3 b}. Septa are sometimes 
 not recognisable at all ; but in other instances their presence 
 can be detected in the form of very rudimentary spiniform or 
 tubercular projections into the interior of the visceral chamber. 
 One of the nearest allies of the form here selected as the 
 type of Pachypora cervicornis, De Blainv., is the P. (Favosites) 
 cristata, E. and H., of the Upper Silurian. The latter, how- 
 ever, is distinguished by the constant presence of minute calices 
 interspersed among the larger annular apertures, by the smaller 
 size of average examples of the corallum, and by the possession 
 of more numerous tabulae, while the septa are often long and 
 
GENERA OF FAVOSITID&. 87 
 
 spiniform, and the mural pores are much smaller. (The only 
 variety of P. cervicornis in which I have observed comparatively 
 numerous tabulae is that from the Devonian rocks of Devon- 
 shire, and I have already given reasons for thinking this to be 
 probably at least varietally distinct from the Eifel form, if not 
 a good species.) 
 
 Formation and Locality. Abundant in the Devonian Lime- 
 stone of Gerolstein in the Eifel. Also not uncommon in the 
 Corniferous Limestone of Wainfleet, Ontario. [Quoted by 
 Milne-Edwards and Haime as occurring in the Devonian of 
 France, Belgium, Germany, Spain, Turkey in Europe, and 
 Britain.] 
 
 Pachypora cristata, Edwards and Haime, sp. 
 (PI. IV., figs. 4-4$, and PL V., figs, i-i b.) 
 
 (?) Madreporites cristatus, Blumenbach, Comment. Soc. Scient. Gott, t. xv. 
 
 p. 154, PL III., fig. 12, 1803. 
 Favosites polymorpha, Lonsdale, in Murchison's Silurian Syst., p. 684, PL 
 
 XV., fig. 2, 1839. 
 
 Lonsdalei, D'Orbigny, Prodr. de Paleont, t. i. p. 49, 1850. 
 cristata, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 
 342, 1851 ; and Brit. Foss. Cor., p. 260, PL LXL, figs. 3 and 4, 
 1854. 
 
 Calamopora cristata, Fr. Schmidt, Sil. Form, von Ehstland, p. 239, 1858. 
 cristata, Ferd. Roemer, Sil. Fauna des West. Tennessee, p. 20, PL 
 
 II., fig. 12, 1860. 
 
 Favosites Lonsdalei, Lindstrom, Ofversigt af Kongl. Vetensk. Akad. ForhandL, 
 1873, P- 22. 
 
 Spec. Char. Corallum dendroid, or sometimes sublobate; the 
 branches generally cylindrical, often irregularly swollen, from two 
 to four or five lines in diameter, dividing at frequent intervals, 
 and terminating in rounded ends. Corallites radiating from 
 the axis of the corallum, and diverging outwards to open on 
 all parts of the free surface ; their walls thickened by scler- 
 enchyma, especially in the neighbourhood of their mouths. 
 Mural pores few in number, apparently uniserial or irregular. 
 Calices rounded, encircled by greatly thickened margins, and 
 usually of two principal sizes, the larger ones often nearly or 
 
88 TABULATE CORALS. 
 
 quite circular, and from half to two-thirds of a line in diameter ; 
 while the smaller ones are intercalated among the preceding, 
 are often subpolygonal or angular, and vary from a quarter to 
 a third of a line in diameter. Septa represented by radiately 
 arranged spinules, or nearly obsolete. Tabulae numerous, 
 complete, usually curved with their convexity downwards, 
 or flexuous. 
 
 Obs. The present species was identified by Milne-Edwards 
 and Haime with the Madreporites cristatus of Blumenbach ; and 
 if this identification be correct, it ought to stand as Pachypora 
 cristata, Blum. sp. Lindstrom has, however, expressed the 
 opinion (loc. jam '/.), that the form described under the above 
 title by Blumenbach was really the Devonian P. (Favosites) 
 cervicornis, De Blainv., and he therefore revives for the form 
 now under consideration D'Orbigny's name of F. Lonsdalei. 
 Not having it in my power to decide whether or not the iden- 
 tification of Milne-Edwards and Haime is well founded, I have 
 preferred to keep the species in the meanwhile under the name 
 by which all British palaeontologists know it, and by which it is 
 described in the two classical treatises of the French authors. 
 
 Pachypora cristata, E. and H., usually presents itself in the 
 form of small branching fragments, which may be cylindrical, 
 or which may be so far dilated as to be almost sublobate. I 
 have never seen any fragments even as large as those figured 
 by Edwards and Haime (Brit. Foss. Cor., PI. LXI., figs. 3, 4), 
 and I should imagine the perfect corallum to have attained no 
 great size. The diameter of the branches is most commonly 
 from two to four lines ; and an examination of its internal struc- 
 ture at once shows it to belong to Pachypora, Lindst, and not 
 to Favosites proper. Transverse sections (PI. V., fig. i) show 
 that the corallites are essentially polygonal, and that their pro- 
 per walls are distinctly recognisable ; but the interior of the 
 tubes is narrowed by a dense deposit of sclerenchyma, which 
 increases in quantity as the aperture is approached, and which 
 leaves only a small oval or circular central space. Longitudinal 
 sections (PI. V., figs, i a and i b) show precisely the same fea- 
 
GENERA OF FA VOSITID^E. 89 
 
 tures. The calices also (PI. IV., figs. 4 a and 4 b) exhibit the 
 thickened lips so characteristic of Pachypora, the proper wall 
 being still marked by a raised line which forms the crest of the 
 calicine margin. The characters of the calices differ to a con- 
 siderable extent in two different groups of examples. In one 
 of these groups which at the same time comprises the smaller 
 forms, with the most regularly cylindrical branches the calices 
 (PI. IV., figs. 4 and 4 a) are markedly circular or annular, open- 
 ing flush with the surface, and having a diameter for the most 
 part of about half a line. Mixed up with these larger calices 
 are smaller ones, which are also more or less circular, and vary 
 from a quarter to a third of a line in diameter. On the other 
 hand, in another great group of specimens in which the cor- 
 allum is usually irregularly swollen, or even sublobate the 
 calices (PL IV., fig. 4 b) are more disproportioned in their 
 dimensions, the larger ones being from two-thirds to even 
 three-fourths of a line in diameter, while the small ones are 
 wedged in among the bigger openings, and are mostly poly- 
 gonal or angular. The large calices, also, are not always mark- 
 edly circular, but are often oval, and they have a decided ob- 
 liquity to the surface, which varies in amount in different speci- 
 mens. (I have never seen any example with an obliquity so 
 great as that figured by Milne-Edwards and Haime, Brit. 
 Foss. Cor., PI. LXI., fig. 4 a, where the front wall of each 
 corallite is free and exposed for a considerable distance ; but 
 I have seen an approach to this condition. Possibly this was 
 a weathered specimen.) Marked examples of these two condi- 
 tions may easily be selected, which are so different in appear- 
 ance that they might quite well be regarded as distinct species. 
 After an examination, however, of a large number of specimens, 
 I find the two groups to shade into one another so impercep- 
 tibly, that I cannot regard them as specifically separable, I 
 agree, therefore, with Milne- Ed wards and Haime, who recog- 
 nised the two conditions of the species to which I have just 
 referred, and who regarded the smaller form, with the rounded 
 calices, as the type of the species ; while they figured the form 
 
90 TABULATE CORALS. 
 
 with the larger and more oblique calices under the name of 
 varietas major (Brit. Foss. Cor., PL LXL, fig. 4 a). I thus 
 regret to find myself unable to adopt the opinion of my friend 
 Dr Lindstrom on this point, who regards the latter form (viz., 
 var. major) as the type of P. cristata, while he considers the 
 examples with the annular calices as specifically distinct. 
 
 In a few instances, I have noticed the existence of an oper- 
 culum closing the mouth of a tube, but this seems to be un- 
 usual. The condition of the septa varies. In some examples 
 they cannot be recognised at all, whereas in others (certainly 
 not so commonly) the mouths of the corallites are seen to 
 be clearly marked by radiating ridges. Thin transverse and 
 tangential sections (PI. V., fig. i) show the same differences. 
 Usually such sections exhibit no traces of septa, or only a few 
 rudimentary tubercles, but sometimes there proceed tolerably 
 long spines into the interior of the tube. Similar spines are 
 present in most longitudinal sections, but in very varying num- 
 bers. Sometimes (PI. V., fig. i a} there are very few of them ; 
 but in other instances (PI. V., fig. i b) there are numerous 
 pointed spines which spring from the walls, and are directed 
 upwards into the visceral chamber. It seems almost certain 
 that these spines are truly septa, though some of them may 
 perhaps be of the nature of incomplete tabular. The tabulae 
 are well developed, about five or six in the space of two lines, 
 complete, usually curved, with their convexities turned towards 
 the base of the corallum, sometimes irregularly flexuous. I 
 have only been able to investigate the mural pores by means 
 of thin vertical sections, in which these openings may be often 
 partially detected. They are of no great size, and appear to 
 be either uniserial or irregular. 
 
 P. cristata, E. and H., is distinguished from P. lamellicornis, 
 Lindst., by the different form of the corallum, the presence of 
 small calices interspersed among the larger ones, and the much 
 greater development of the tabulse. From the P. cervicornis, 
 De Blainv., of the Devonian, the present species is separated 
 by slight but upon the whole readily recognisable differences 
 
GENERA OF FAVOSITID^E. 91 
 
 in external appearance : while its calices are more conspic- 
 uously annular, and more obviously of two sizes, its tabulae 
 are more numerous (as compared with typical examples of 
 the former), and its mural pores are markedly smaller and 
 apparently more numerous. 
 
 Formation and Locality. Common in the Wenlock Lime- 
 stone of Benthall Edge, and Dormington Quarry, near Stoke- 
 Edith. (Milne - Edwards and Haime and Lindstrom quote 
 it from a corresponding horizon in Gotland. It is also very 
 probable that some of the so-called Cladoporce of the Niag- 
 ara and Lower Helderberg groups of North America really 
 belong to this species ; but there are at present no means of 
 verifying this conjecture.) 
 
 Pachypora Fischeri, Billings. 
 (Fig. 16.) 
 
 Alveolites Fischeri, Billings, Canad. Journ., new ser., vol. v. p. 256, fig. 6, 
 
 1860. 
 Fischeri, Nicholson, Report on the Palaeontology of Ontario, 1874, 
 
 P- 57- 
 Cladopora Fischeri, Rominger, Foss. Cor. of Michigan, p. 47., PI. XIX., figs. 
 
 i and 4, 1876. 
 
 Pachypora Fischeri, Nicholson and R. Etheridge, jun., Journ. Linn. Soc., vol. 
 xiii. p. 362, PI. XX., figs. 18-20, 1877. 
 
 Spec. Char, Corallum forming flattened expansions or 
 fronds, of a palmate form, and from one to four lines in 
 thickness, and often of considerable size. Corallites disposed 
 obliquely to the surfaces, diverging in opposite directions from 
 a central plane, and opening by distinct calices over the whole 
 free surface of the corallum on both sides of the frond. 
 The corallites are subpolygonal in shape, but their interior 
 is thickened by a secondary deposit of sclerenchyma, arranged 
 in concentric laminae, so as to leave only a comparatively small 
 oval or circular central tube. Calices sometimes rounded or 
 oval, sometimes markedly oblique and subtriangular both 
 conditions sometimes prevailing in different parts of the same 
 specimen. About three, or sometimes four, calices in the 
 
92 TABULATE CORALS. 
 
 space of two lines, measured transversely as regards the axis 
 of the frond. Calicine margins much thickened. Septa ob- 
 solete ; tabulae few, remote, and complete. Mural pores few, 
 large-sized, irregularly distributed. 
 
 Obs. The above diagnosis gives all the principal characters 
 of this species. Originally described by Mr Billings, and 
 subsequently by myself, as an Alveolites, it was referred by Dr 
 Rominger to Hall's genus Cladopora. I have, however, already 
 given my reasons for thinking that this generic name cannot 
 be advantageously retained ; and the present form, at any rate, 
 differs from those to which Professor Hall originally gave this 
 title, in the possession of well-developed tabulae. At a still later 
 date it was referred by Mr R. Etheridge, jun., and myself to 
 Pachypora, Lindst. ; and its very close alliance with P. lamellicor- 
 nis, Lindst., renders the propriety of this reference undeniable. 
 The specific differences between these two forms are, however, 
 numerous ; and though it possesses the internal structure of 
 Pachypora, the present form in external characters very nearly 
 approaches Alveolites, Lam., and thus forms a connecting-link 
 between these two generic types. The corallum in P. Fischeri^ 
 Bill. (fig. 16, A), is a palmate, flattened, and undulated ex- 
 pansion, which doubtless attained considerable dimensions 
 though the larger examples (three inches or more in length) 
 are always broken ; while the thickness varies from one to three 
 or four lines. At its base, the corallum was fixed to some 
 foreign body, but its entire free surface is occupied by the 
 calices, the corallites diverging regularly from an imaginary 
 plane midway between the two flat surfaces of the frond 
 (fig. 1 6, B). The corallites thus open obliquely on the surface, 
 but the apparent obliquity of the calices varies greatly. In 
 some examples (fig. 16, c) the calices are very slightly oblique, 
 oval or circular, and in these there are about three calices in 
 the space of two lines, in whatever direction the measurement 
 be taken as regards the frond. In other cases (fig. 16, D) the 
 calices are oblique, oval, or subtriangular, or lozenge-shaped, 
 sometimes with the thin lower lip characteristic of Alveolites, 
 
GENERA OF FA VOSITIDM. 
 
 93 
 
 and in these there are generally four calices in the space of 
 two lines measured across the frond, and five of these apertures 
 on the same space measured vertically. These differences, 
 
 Fig. 16. A, A young but imperfect specimen of Pachypora fiischeri, Bill., from the Hamilton 
 group of Ontario, of the natural size, showing the general form and characters of the 
 corallum ; B, Vertical section of the corallum, at right angles to its flat surfaces, enlarged 
 three times, showing the divergence of the corallites from a central plane ; c, Portion of 
 the surface of a specimen with rounded calices, enlarged five times; D, Portion of the 
 surface of a specimen with oblique calices, enlarged five times ; E, Tangential section of 
 a specimen with oblique calices, enlarged six times ; F, Tangential section of a specimen 
 with rounded calices, enlarged six times ; G, Vertical section of a specimen with oblique 
 calices, parallel with its flat surfaces, enlarged six times, showing tabulae and mural pores. 
 
 however, are not of specific value, since intermediate conditions 
 are common, and different parts of the same specimen may 
 exhibit both of these states. In both cases, also, thin sections 
 taken in a plane tangential to the surface and just below it, 
 show that the walls of the calices have the characteristic 
 thickening of Pachypora (fig. 16, E and F), this being due to the 
 
94 TABULATE CORALS. 
 
 deposition of delicate concentric laminae of sclerenchyma within 
 the interior of the corallites. The same thickening is shown 
 by the comparative remoteness of the openings of the calices 
 on the surface ; but this feature is much more conspicuous in 
 specimens in which the calices are rounded than in those in 
 which they are oblique and more closely crowded together. 
 Sections taken along the median plane of the frond (fig. 16, G), 
 and cutting the tubes longitudinally, also exhibit much-thick- 
 ened walls and correspondingly contracted visceral chambers. 
 Sections of this kind further show that complete and delicate 
 tabulae are always present, though few in number, and placed 
 wide apart, while the mural pores are few in number, large in 
 size, and quite irregular in position. Lastly, there are no traces 
 of septa to be detected, even in a rudimentary form, either in 
 tangential or in longitudinal sections. 
 
 Formation and Locality. Common in the Hamilton for- 
 mation (Devonian) of Arkona, Ontario ; also, rarely, in the 
 Corniferous Limestone (Devonian) of Port Colborne, Ontario. 
 
 Pachypora frondosa, Nicholson. 
 (Fig. 17.) 
 
 Alveolites frondosa, Nicholson, Geol. Mag., new ser., Dec. II., vol. i. p. 15, 
 PI. II., fig. 2, 1874 ; and Rep. on the Paleontology of Ontario, 
 
 1874, P- 57- 
 Pachypora frondosa^ Nicholson and Etheridge, jun., Journ. Linn. Soc., vol. 
 
 xiii. p. 362, 1877. 
 Cladopora Canadensis, Rominger, Foss. Cor. of Michigan, p. 48, PL XIX., 
 
 % 3> J 877- 
 
 Spec. Char. Corallum forming elongated palmate flattened 
 expansions, which grew in an erect position from a rooted base, 
 and which have their entire free surfaces covered with the open 
 mouths of the corallites. In size, the corallum is usually from 
 half an inch to an inch and a half in width, with a height of 
 two inches or more, and a thickness of generally two lines or 
 less. The corallites diverge from an imaginary plane midway 
 between the two flat surfaces of the expansion, and open ob- 
 
GENERA OF FAVOSITIDJE. 
 
 95 
 
 liquely on the surface. Walls thickened, and completely amal- 
 gamated in contiguous tubes. Calices subtriangular, oval, semi- 
 lunar, or sometimes fissure-like, with thickened margins, but 
 generally with a sharp lower lip which may be indented with 
 one or more emarginations. The arrangement of the calices 
 is very irregular, but they are often disposed in diagonal lines 
 running across the frond, and there are usually five or six of 
 them in the space of two lines. One or two inward projections 
 of the wall of the corallites on one side may represent septa ; 
 or these structures may be wholly wanting. Tabulae obsolete, 
 or few, remote, and complete. Mural pores apparently very 
 few and remote. 
 
 Obs. In its general habit and form this species (fig. 17) 
 closely resembles P. Fischeri, Bill., both constituting thin flat- 
 
 rig. 17. A, A fragment of Pachypora frondosa, Nich., of the natural size, shown as if 
 attached to some foreign body, and with the extremities of the frond restored in outline ; 
 B, A small portion of the surface of the same, enlarged five times ; c, Tangential section 
 of the same, enlarged seven times ; D, Vertical section of the same, similarly enlarged ; 
 E, Section at right angles to the flat surfaces of the frond, enlarged twice, showing the 
 divergence of the corallites from a central plane, together with a few tabulse. From the 
 Hamilton group of Arkona. 
 
 tened fronds, attached basally to some foreign object, and hav- 
 ing the corallites so arranged in reference to the median plane 
 of the expansion as to open over the whole of both of the flat 
 
96 TABULATE CORALS. 
 
 surfaces as well as on the edges of the corallum. In spite, 
 however, of this close general resemblance, I do not yet feel 
 absolutely satisfied that the present species is rightly referred 
 to the genus Pachypora, Lindst. ; and it will require more ex- 
 tended investigations than I have hitherto been able to carry 
 out before this point can be finally settled. In fact, P. frondosa 
 exhibits a union of the features which characterise P achy p or a 
 proper with those distinctive of Cosnites, and I am not sure 
 that it will not be ultimately necessary to remove it to the 
 latter genus. This point is especially shown by the calices. 
 These openings, though never actually rounded or polygonal, 
 are often oval, and they are seen in sections parallel with the 
 surface (fig. 17, c) to be surrounded by a dense deposit of 
 sclerenchyma, as in Pachypora. On the other hand, the calices 
 are commonly subtriangular, and in parts of the frond they are 
 generally quite crescentic or even fissure-like, while the lower 
 lip is sharp and thin, and may project inwards as a single or 
 double tooth, as in Ccenites. Moreover, though the walls of 
 the corallites are thickened, and the calices thus rendered re- 
 mote, I have failed to detect the delicate concentric laminse of 
 sclerenchyma so characteristic of Pachypora ; and the walls of 
 contiguous tubes are completely incorporated, and exhibit no 
 clear line indicating their original separateness. The com- 
 paratively numerous septal spines of P. lamellicornis, Lindst, 
 are here wanting, but one or two ridges on the interior of one 
 of the walls of the corallites may represent septa. In other 
 cases, however, the tubes appear in transverse section (fig. 
 17, c) to be oval or rounded, and there may be no traces of 
 septal ridges or tubercles. Thin sections taken along the 
 median plane of the expansion, and cutting the tubes longi- 
 tudinally (fig. 1 7, D), show no signs of tabulae, or but unsatis- 
 factory ones ; but sections taken at right angles to the flat 
 surfaces of the frond (fig. 1 7, E) show that these structures are 
 at any rate occasionally present, when they are few, remote, and 
 complete. I have not been able to discover mural pores other- 
 wise than by the presence of lateral communications between 
 
GENERA OF FAVOSITID^. 
 
 97 
 
 the visceral chambers of contiguous tubes, as seen in long sec- 
 tions (fig. 17, D) ; and the presence of a few remote and large- 
 sized pores may be regarded as thus sufficiently established. 
 Taking all its known characters into consideration, I am dis- 
 posed to regard the present species as congeneric with P. 
 Fischeri) Bill., though with affinities to Ccenites. 
 
 There cannot be any question as to the identity of P. 
 frondosa, Nich., with the form more recently described by Dr 
 Rominger from the Devonian rocks of North America under 
 the name of Cladopora Canadensis (loc. cit^) I have also a 
 number of specimens from the Devonian limestones of the 
 Eifel, which appear to be undistinguishable from P. frondosa; 
 but as my collections from this region are as yet imperfectly 
 examined, I shall leave this point open in the meanwhile. 
 
 Formation and Locality. Common in the Hamilton forma- 
 tion (Devonian) at Arkona, Ontario. 
 
 Genus STRIATOPORA, Hall, 1852. 
 (Pal. N. York, vol. ii. p. 156.) 
 
 Gen. Char. Corallum dendroid, of simply-dividing cylin- 
 drical stems. Corallites essentially polygonal, diverging from 
 an imaginary central axis, their walls greatly thickened by a 
 secondary deposit of sclerenchyma, which increases in amount 
 as their mouths are approached. Calices in the form of cir- 
 cular apertures surrounded by a cup-shaped thickened margin, 
 the floor of which is striated by rudimentary septal ridges. 
 Septal spines in vertical rows occasionally present. Tabulae 
 few, remote, complete. Mural pores comparatively numerous, 
 circular, irregularly distributed. 
 
 O6s. The first species of this genus which was described or 
 figured is the Striatopora lowensis of Dale Owen (=S. rugosa, 
 Hall), of which its author gave a brief description under the 
 name of Cyathopora lowensis (Rep. Geol. Expl. Iowa, Wis- 
 consin, and Illinois, p. 69, 1844). It is not necessary here to 
 
 G 
 
98 TABULATE CORALS. 
 
 enter into the discussion raised by Meek and Worthen (Geol. 
 Survey of Illinois, vol. iii. p. 368, 1868), as to whether Dr Dale 
 Owen is entitled to priority, in the sense that Hall's name of 
 
 Striatopora should give way to 
 Cyathopora. There is no doubt 
 at all that Cyathopora lowensis, 
 Dale Owen, is a genuine Stria- 
 topora ; but the fact that Dr Owen 
 gave no separate description of 
 
 Fig. 18. Fragment of Striatopora flexu- the genUS Cyathopora, COUpled With 
 osa, Hall, of the natural size. Niagara 1 i . M . - . . 
 
 formation. After Hail. the close similarity of this name 
 
 to the entirely different Cyatho- 
 pora of Michelin, would render it highly undesirable to 
 supplant the well -recognised title of Striatopora, even if 
 it were demonstrable that strict justice would require this 
 change. 
 
 The genus Striatopora was very briefly defined by Hall 
 (loc. citl), and its zoological relations are left undecided ; but 
 Dr Rominger (Foss. Cor. of Michigan, p. 57) has correctly seized 
 its true affinities, and has placed it in the family of the Favo- 
 sitidce, a position to which I had independently and simulta- 
 neously assigned it (Art. " Corals," Encyclopaedia Brit., 9th ed., 
 vol. vi. p. 377). Microscopic examination, in fact, by means 
 of thin sections, places it beyond a doubt that Striatopora , 
 Hall, is an immediate relative of Favosites itself, and that it 
 agrees so closely with Packypora, Lindst, that the two may 
 be safely regarded as mere offshoots of a common stem. All 
 the known species of Striatopora possess a ramose corallum, 
 composed of cylindrical stems, which divide in a dichotomous 
 manner, but are not known to inosculate. The corallites 
 diverge in an obliquely -curved manner from a central axial 
 line, and open by large irregularly-sized polygonal calices on 
 all parts of the free surface. The general form and structure 
 of the corallum are thus precisely those of any dendroid species 
 of Favosites ; and the close relationship of the two genera is 
 shown by the existence in Striatopora of numerous circular mural 
 
GENERA OF FAVOSITID^E. 99 
 
 pores, of well-developed though sparse tabulae, and, sometimes 
 at any rate, of spiniform septa. On the other hand, the corallites 
 exhibit, in an even more extreme degree, the thickening of 
 their walls by a secondary concentrically-laminated deposit of 
 sclerenchyma, which is so characteristic of Pachypora, Lindst. 
 There is, indeed, no feature in the way of internal construc- 
 tion which could be brought forward as separating Striatopora 
 from Pachypora ; and in distinguishing these two types we 
 have to fall back upon a well-marked external character. In 
 all the forms of Pachypora, Lindst., namely, the actual orifices 
 of the corallites are but slightly sunk beneath the general sur- 
 face, and they are surrounded by thick and but faintly-crested 
 margins. On the other hand, in all the species of Striatopora, 
 Hall, the circular apertures of the corallites are more or less 
 deeply sunk below the general surface, and open at the bottom 
 of an expanded polygonal cup (fig. 18), the actual margins of 
 which are as thin as the lips of the calices in a species of 
 Favosites. This feature is quite sufficient to distinguish Striato- 
 pora from either Favosites or Pachypora, between which it is in 
 this respect an intermediate link ; though it must be admitted 
 that the filling up of the cup-like terminations of the corallites 
 by the matrix to the level of their free margins, sometimes 
 renders it difficult to apply this distinction in practice. More- 
 over, the floor of the cup-shaped calices of Striatopora is seen 
 in perfect specimens to be generally striated in a radiating 
 manner, with delicate ridges or rows of tubercles, representing 
 septa (fig. 1 8) ; though this character also cannot be constantly 
 recognised, and is present in a minor degree in some forms of 
 
 I Pachypora (e.g., P. cristata, E. and H.) 
 The geological range of Striatopora, so far as known, is a 
 limited one, all the described species being either Upper Silu- 
 rian or Devonian in age. I have made a careful microscopic 
 examination of S. Linneana, Bill., from the Hamilton group 
 of Ontario, and also of S. Haiti, Lindst, from the Wenlock 
 Limestone of Gotland, but I shall merely give a brief descrip- 
 tion of the former of these. So far as I am aware, the genus 
 
ioo TABULATE CORALS. 
 
 has not yet been recognised as British, though it will doubt- 
 less yet be found to be represented in our area. 
 
 Striatopora Linneana, Billings. 
 (PL V., figs. 2-2 d.) 
 
 Striatopora Linneana, Billings, Canad. Journ., new ser., vol. v. p. 253, 
 
 fig. i, 1860. 
 Linneana, Nicholson, Rep. on the Palaeontology of Ontario, 1874, 
 
 P- 59- 
 Linneana, Rominger, Foss. Cor. of Michigan, p. 59, PI. XXIII., 
 
 figs. 5 and 6, 1877. 
 
 Spec. Char. Corallum dendroid, of dichotomously-branched 
 cylindrical stems, which have a diameter of from two to five 
 lines. Corallites polygonal, diverging from the central line of 
 the branches in gentle curves to open on all points of the free 
 surface, their walls greatly thickened by the growth of a de- 
 posit of sclerenchyma, which increases in amount towards their 
 expanded mouths. Calices of very unequal dimensions, the 
 larger ones mostly about one line in diameter, the younger 
 ones of all sizes, intercalated uniformly among those of full 
 growth. The margins of the calices are polygonal and thin, 
 and surround a funnel-shaped or cup -shaped cavity which 
 opens below by a contracted circular orifice into the proper 
 tube-cavity. The thickened neck of the tube exhibits radiating 
 septal ridges or spines, which are continued throughout the 
 length of the tube, but the outer cup appears to be smooth. 
 Tabulae few, remote, complete. Mural pores moderately nu- 
 merous, irregularly distributed. 
 
 Obs. There is little need to add any remarks to the above 
 description, all the essential characters of the species being 
 further shown in Plate V., figs. 2 - 2 d. All the specimens I 
 have seen are fragmentary, and are in the form of cylindrical 
 or slightly-compressed stems (PI. V., fig. 2), which evidently 
 subdivide only at considerable intervals, as often no branch can 
 be observed. When not filled up with adherent matrix, the 
 calices (PI. V., fig. 2 a) at once show the 'characters of Striato- 
 
GENERA OF FA VOSITID^E. Io i 
 
 pora, being in the form of deep cups, surrounded by thin poly- 
 gonal margins, with a much smaller rounded or oval aperture 
 at the bottom, leading into the visceral chamber. Tangential 
 sections taken close below the surface (PI. V., fig. 2 c] show 
 that the throat of the tube is beset with a variable number of 
 radiating spines, representing the septa ; and similar structures 
 may often be detected within the tube-cavity itself. Transverse 
 sections (PI. V., 2 b] show (like the preceding) that the walls 
 of the corallites are immensely thickened by numerous delicate 
 concentric laminae of sclerenchyma deposited in their interior ; 
 and they are specially instructive as exhibiting the varia- 
 tion of the amount of this secondary deposit in different 
 parts of the corallites. Thus, in the centre of such a section 
 the vertically - placed tubes in the axis of the branch are 
 cut across at right angles, and here their diameter is com- 
 paratively small, and the extent to which they are filled up is 
 less. On the contrary, the outer portion of such a section cuts 
 obliquely through the corallites in the terminal part of their 
 course, just as they curve outwards to open on the surface. At 
 this point, therefore, the tubes are seen to be considerably ex- 
 panded, and a proportionately large amount generally about 
 two-thirds of the actual space comprised within the proper 
 walls of the corallites is here filled up with sclerenchyma. 
 Vertical sections (PI. V., fig. 2 d) show the general course of the 
 tubes, and also the same progressive thickening of the walls 
 as the mouth is approached. They show at the same time 
 that the proper walls of the corallites never become obliterated ; 
 that the visceral chamber is crossed by remote, delicate, hori- 
 zontal, and complete tabulae ; and that contiguous tubes are 
 placed in communication by comparatively abundant circular 
 mural pores, which in all respects appear to resemble those 
 of Favosites itself, except that they appear to have a quite 
 irregular distribution. 
 
 Formation and Locality. Rare in the Hamilton group 
 (Devonian) of Arkona, Ontario. 
 
102 TABULATE CORALS. 
 
 Genus TRACHYPORA, Edwards and Haime, 1851. 
 (Pol. Foss. des Terr. Pal., p. 305.) 
 
 Gen. Char. Corallum dendroid, of compact cylindrical stems, 
 attached basally to foreign bodies, and composed of conical 
 corallites which diverge with an increasing curvature from an 
 imaginary axial line to open on all parts of the free surface. 
 Corallites essentially polygonal, in close contact, their proper 
 walls usually not obliterated, and in no case separated by the 
 intervention of a true ccenenchyma. Interior of the tubes con- 
 tracted by the deposition of numerous concentric layers of scler- 
 enchyma, which increase in amount as the surface is approached. 
 Calices superficially widely distant from one another, arranged 
 in irregular longitudinal rows, the interspaces between them, 
 formed by their enormously-thickened lips, being ornamented 
 with grooves or ridges. Septa represented by radiately-placed 
 spines or tubercles, or obsolete. Tabulae few, remote, com- 
 plete. Mural pores generally well marked, but few and 
 irregular. 
 
 Obs. The genus Trachypora was founded by Milne- 
 Edwards and Haime for the reception of the single species 
 T. Davidsoni, from the Devonian formation of France ; and 
 it was placed by these eminent zoophytologists (loc. city in 
 the family of the SeriatoporidUe, in the immediate neighbour- 
 hood of Dendropora, Mich., and Rhabdopora, E. and H., both 
 also founded upon single species. These three types, in fact, 
 if really capable of generic separation at all, are apparently 
 most closely allied to one another ; and as I do not possess 
 any specimens of the two latter, and as their microscopic 
 structure is wholly unknown, I shall make the few remarks 
 concerning them which may be necessary in connection with 
 the present genus, with the anatomy of which I am better 
 acquainted. 
 
 My knowledge of the genus Trachypora is based upon a 
 minute examination of T. ornata, Rom., and T. elegantula, 
 
GENERA OF FAVOSITID^E. 103 
 
 Bill., both of which are, in my opinion, unmistakably con- 
 generic with the type-species, T. Davidsoni, E. and H., and 
 were so regarded by their respective founders. The investi- 
 gation of thin sections of these two species has led me to 
 entirely coincide in all points of substantial importance with 
 the account given of the genus by Dr Rominger, who unites 
 it with Dendropora, Mich. (Foss. Corals of Michigan, p. 60, 
 1877). It becomes quite clear, then, that there is no real 
 affinity between Trachypora, E. and H., and Seriatopora, 
 Lam. Not only is the columella of the latter genus totally 
 wanting in the former, but thin sections place it beyond a 
 doubt that there exists in Trachypora absolutely nothing of 
 the nature of a ccenenchyma. It is true that the apertures 
 of the calices are widely removed from one another, and 
 that the dense calcareous tissue which separates them is 
 superficially sculptured in various ways ; but tangential sec- 
 tions (such as fig. 3 , PI. V.) show that the appearance thus 
 produced and mistaken, very naturally, by Milne- Edwards 
 and Haime as indicating the presence of an abundant ccenen- 
 chyma is really due to quite a different cause. In reality 
 there is no ccenenchyma at all, and the essentially polygonal 
 corallites are in close contact by their walls throughout. The 
 wide interspaces which separate the openings of the calices 
 are truly formed by the extraordinary thickening of the walls 
 caused by the deposition of numerous concentric layers of 
 sclerenchyma in the interior of the tubes. The actual struc- 
 ture is, therefore, precisely that of Pachypora, Lindst, and 
 Striatopora, Hall, so far as this point is concerned with the 
 difference, that the thickening of the immediate periphery 
 of the calices is carried to a much more extreme extent, 
 and that the free surface separating the openings of the 
 calices exhibits the peculiarity of being ornamented with 
 grooves or ridges. This last -mentioned feature is, indeed, 
 the only definite character by which such species of the 
 genus as T. ornata, Rom., can be separated from Pachy- 
 pora, while other species (such as T. Davidsoni, E. and H., 
 
I04 TABULATE CORALS. 
 
 and T. elegantula, Bill.) exhibit the additional peculiarity that 
 the remote calices are upon the whole distributed in a small 
 number of vertical rows. Not only is there no true ccenen- 
 chyma in Trachypora, but the propriety of the step taken 
 by Dr Rominger in placing the genus among the Favositidce 
 is further shown conclusively by the fact that the cavities 
 of contiguous tubes are placed in communication by means 
 of a system of mural pores the importance of this fact not 
 being diminished by the comparatively small number of these 
 openings. It should be added that in some forms (including 
 the type-species, T. Davidsoni] such apertures in the walls of 
 the corallites have not yet been recognised ; but it may be 
 confidently expected that these structures will yet be brought 
 to light by a sufficiently minute examination. Lastly, Milne- 
 Edwards and Haime state that, in T. Davidsoni, "on ne dis- 
 tingue pas de cloisons ; " and the same statement will apply to 
 T. elegantula, Bill. In other cases, however, and especially in 
 T. ornata, Rom., the septa are quite recognisable as a well- 
 developed series of spines arranged in vertical rows. 
 
 While I am unable at present to recognise any true relation- 
 ship between Seriatopora and Trachypora, I ought to add that 
 I have had no opportunity of examining microscopic sections 
 of the former, and that my conclusions are therefore based 
 upon the published descriptions and figures of Seriatopora. 
 There is a close general resemblance between such forms of 
 Trachypora as T. elegantula. Bill., on the one hand, and certain 
 forms of Seriatopora (e. g., Seriatopora elegans, Hist. Nat. des 
 Coralliaires, PI. F 4, figs. 3 a, 3 b) on the other hand ; and 
 it is possible that a microscopic examination of the latter may 
 show that this resemblance is based upon a real identity of 
 structure. All that I can affirm is, that the species of Trachy- 
 pora assuredly do not possess either a proper coenenchyma or 
 a columella, organs which are said to be present in Seriatopora, 
 and that there is thus established a wide difference in syste- 
 matic position. In the same way there is a striking resem- 
 blance between Trachypora ornata, Rom., and the living Pocil- 
 
GENERA OF FAVOSITID&. 10$ 
 
 lopora ac^tia, Lam. (see Hist. Nat. des Cor., PI. F 4, fig. 2) ; 
 but I have no means of knowing how far this resemblance may 
 express an actual agreement in anatomical structure, and the 
 former assuredly does not possess the ccenenchyma stated to 
 exist in the latter coral. 
 
 As distinguished by Milne-Edwards and Haime (Pol. Foss. 
 des Terr. Pal., pp. 304, 305), Trachypora is separated from 
 Dendropora, Mich., by the fact that the " ccenenchyma " (that 
 is, the thickened margin of the calices) is smooth, or almost so, 
 in the latter, whereas in the former it is adorned by irregular 
 vermiculate or sub-echinulate strise. The genus Rhabdopora 
 E. and H., again, is said to be characterised by having four- 
 sided branches, with an echinulate " ccenenchyma," and calices 
 arranged in simple longitudinal series, the septa being very 
 distinct and slightly exsert. Professor Martin Duncan, in his 
 masterly " Third Report on the British Fossil Corals " (Rep. 
 Brit. Assoc., 1872), concludes as I think, rightly that the 
 maintenance of a generic distinction between Dendropora, 
 Mich. (1845), and Rhabdopora, E. and H. (1851), is quite 
 untenable ; but I am unable to follow this distinguished 
 authority in his further conclusion that both of these genera are 
 identical with Seriatopora, Lam., which, in turn, is said to be 
 inseparable from Pocillopora, Lam., the name of Acropora, 
 Oken, being rehabilitated for the reception of all of these. 
 Trachypora, E. and H., is, on the other hand, doubtfully 
 referred to the Alcyonaria. The researches of Verrill (Trans. 
 Conn. Acad., vol. i., 1868) have, however, shown that Pocillo- 
 pora is closely related to the Oculinidcz ; and it is highly prob- 
 able that Seriatopora, whether generically separable or not, 
 will ultimately be found to occupy a similar zoological position. 
 Dr Rominger, on the contrary, merges Trachypora under 
 Dendropora, Michelin, holding that the surface-ornamentation 
 is a character of merely superficial importance. In this view I 
 should be quite prepared to concur, if it were once shown that 
 Dendropora explicita, Mich., the type of the genus, possessed 
 the internal structure of Trachypora ; but in the absence of any 
 
106 TABULATE CORALS. 
 
 information as to the intimate characters of the former, I think 
 it safer to retain Trachypora in the meanwhile as a distinct 
 genus. This genus, as will be abundantly evident from what 
 has been said already, is incontrovertibly referable to the 
 Favositickg) and is very nearly related to Pachypora, Lindst. 
 If, as is very probable, an examination of the minute structure 
 of Dendropora explicita, Mich., should show that this too is 
 a Favositoid, then the genus Dendropora, Mich, (including 
 Rhabdopora, E. and H.), will have to take the place of Trachy- 
 pora, E. and H., and the classification and arrangement of this 
 difficult group will have been materially improved. 
 
 All the known species of Trachypora, E. and H., are Devo- 
 nian ; but its union with Rhabdopora would extend the range 
 of the type into the Carboniferous, and I possess a specimen 
 from the Wenlock Limestone of Longhope, which appears to be 
 undistinguishable from Dendropora. It is probable, therefore, 
 that the genus will ultimately be shown to range from the 
 Upper Silurian to the Carboniferous ; but its exact limits must 
 remain at present uncertain. 
 
 Trachypora ornata, Rominger, sp. 
 (PI. V., figs. 3-3 A) 
 
 Dendropora ornata, Rominger, Foss. Corals of Michigan, p. 61, PI. XXIII., 
 fig. i, and PI. XXIV., fig. 2. 
 
 Spec. Char. Corallum composed of cylindrical stems, 
 generally about two or three lines in diameter, branching 
 dichotomously at intervals of half an inch or more. The 
 openings of the tubes on the surface are oval or circular, 
 variable in size, the larger ones mostly about two-thirds of 
 a line in diameter, and either raised above the general surface 
 by a projecting rim, or apparently level with it. Openings of 
 the tubes separated by dense calcareous tissue, which is really 
 formed by the thickening of the walls of the corallites, and 
 which may separate the actual orifices to their own diameter 
 or more. The proper walls may or may not be superficially 
 
GENERA OF FAVOSITIDAL. 107 
 
 recognisable as subpolygonal lines surrounding each orifice, 
 and the thickened margins are adorned with tubercles or 
 ridges arranged in a more or less conspicuously radiate 
 manner round the calices. Septa represented by rows of 
 spinules arranged radiately in vertical rows. Tabulae few, 
 remote, complete. Mural pores few, large -sized, irregularly 
 distributed. 
 
 Obs. This pretty species is readily distinguished from the 
 forms most nearly allied to it by the peculiar ornamentation 
 of the incrassated margins of the calices, which -are ornamented 
 with rows of granules or discontinuous ridges invariably having 
 a more or less clearly recognisable radiate arrangement (PI. V., 
 fig. 3 #) Vertical sections show that the walls of the coral- 
 lites are greatly thickened (PI. V., fig. 3 b}, and that this 
 thickening is rapidly augmented in amount towards the open- 
 ings of the tubes ; but considerable differences obtain in the 
 extent to which this process is carried. In some instances, the 
 thickening is so great that the actual openings of the corallites 
 appear to be separated by dense calcareous tissue to their own 
 diameter or even more ; but in others they are much more 
 closely approximated, owing to the comparative thinness of the 
 walls. Vertical sections (PI. V., fig. 3 b) further show that the 
 walls of the corallites are always distinctly recognisable and 
 closely contiguous, no ccenenchymal tissue being present ; that 
 the visceral chambers remain open throughout their entire 
 length, though greatly contracted in diameter by the thicken- 
 ing of the walls ; that there are a few, remote, horizontal 
 tabulae ; that the septa are represented by rows of spinules ; 
 and that the cavities of the tubes are placed in communication 
 by a few large pores, of the same character as those of Favo- 
 sites, but quite irregular in their distribution. Tangential 
 sections (PI. V., fig. 3 c) show the same thickening of the walls 
 of the corallites as do vertical slices, and show distinctly that 
 this thickening is due to the deposition of successive thin con- 
 centrically-disposed laminae of sclerenchyma within the interior 
 of the tubes. They further show that the actual polygonal 
 
io8 TABULATE CORALS. 
 
 walls of the corallites remain quite distinct and unobliterated, 
 in spite of the thickening to which they are subjected. In 
 some instances, if the plane of the section is just below the 
 actual surface, the dense tissue surrounding the cavity of the 
 visceral chamber may exhibit small discontinuous cavities ; but 
 these are clearly merely spaces in the interior of the super- 
 ficial tubercles and ridges surrounding the opening of the 
 calices (as seen in the lower part of the section figured in 
 fig. 3 , PI. V.) Lastly, tangential sections show that the 
 cavities of the tubes are surrounded by short, blunt, septal 
 spines. Transverse sections taken at right angles to the axis 
 of the corallum show no features of special importance. 
 
 Formation and Locality. In shales belonging to the Hamil- 
 ton formation, at Canandaigua, New York. (Dr Rominger's 
 specimens are also from the Hamilton group.) 
 
 Trachypora elegantula, Billings. 
 (PL V., figs. 4-4;.) 
 
 Trachypora elegantula, Billings, Canadian Journ., new sen, vol. v. p. 254, 
 
 figs. 2-4. 
 elegantula, Nicholson, Report on the Palaeontology of Ontario, 
 
 1874, p. 59. 
 Dendropora elegantula^ Roniinger, Report on the Foss. Cor. of Michigan, 
 
 p. 63, PL XXIII., fig. 2. 
 
 Spec. Char. Corallum ramose, of slender, cylindrical stems, 
 which have generally a diameter of from one to two lines, and 
 branch dichotomously at angles of about 75. Corallites 
 conical, nearly or quite vertical in the centre of the branches, 
 and curving gently outwards to open obliquely on the surface 
 in generally four longitudinal rows of calices, sometimes with 
 supplementary and irregularly -distributed apertures in addi- 
 tion. The central tubes of the corallites are greatly thickened 
 by the deposition of concentric layers of sclerenchyma, which 
 more or less obliterate the proper walls as distinct structures, 
 though the boundaries of contiguous tubes still remain separate. 
 The orifices of the calices are oval, their long axes parallel 
 
GENERA OF FAVOSITID^E. 109 
 
 with that of the stems, two-thirds or three-fourths of a line in 
 their long diameter, and about half a line across, surrounded 
 wholly or for their lower two-thirds by a slightly-elevated rim, 
 which is sometimes marked with radiating striae. The thick- 
 ened margins of the calices separate contiguous apertures to a 
 width about equal to the long diameter of the latter, and form 
 by their union dense interstitial spaces, which are marked by 
 slightly flexuous broken striae. Septa apparently obsolete. 
 Tabulae few in number or seemingly absent. Mural pores not 
 recognised. 
 
 Obs. The external characters of this species, as given in the 
 above diagnosis (PI. V., figs. 4 and 4 a), sufficiently separate it 
 from all the known forms belonging to the genus. The inter- 
 nal structure, however, presents various points which are as 
 yet not sufficiently elucidated, the remarkable density of the 
 corallum rendering the preparation of satisfactory microscopic 
 sections a matter of exceptional difficulty. In most of its 
 structural features, T. elegantula, Bill., does not differ greatly 
 from such forms as T. ornata, Rom., with which it is undoubt- 
 edly congeneric ; but the thickening of the corallites by a 
 secondary deposit of sclerenchyma is carried in the present 
 form to an extreme extent. This is seen particularly in the 
 fact (as shown both by transverse and vertical sections) that the 
 actual walls of the corallites are more or less obliterated (PI. 
 V., figs. 4 b and 4 c], and are not present as distinct partitions 
 definitely circumscribing the individual tubes. In the centre of 
 the stem, where the thickening has not been excessive, the 
 walls are still distinctly recognisable (PI. V., fig. 4 b} ; but as 
 the thickening increases in approaching the surface, the definite 
 lines indicating the proper walls disappear, and the boundaries 
 of contiguous corallites are now only marked by an obscure but 
 still quite unmistakable band of thickened tissue, occupying 
 the place of the wall (PI. V., fig. 4 c). On the surface, the 
 polygonal margins of the calices which are quite recognisable 
 in T. ornata, as ridges surrounding the actual orifices of the 
 tubes at some little distance are no longer to be detected at 
 
no TABULATE CORALS. 
 
 all ; and the calices now appear as if sunk in a dense ccenen- 
 chyma, superficially adorned with discontinuous striae (PI. V., 
 fig. 4 a). Moreover, a careful microscopic examination shows 
 that this dense interstitial tissue is, in parts at any rate, ren- 
 dered minutely porous by the presence of numerous excessively 
 small cavities. 
 
 The general appearances presented by this species as 
 apparently also by the type-species T. Davidsoni, E. and H. 
 are entirely such as would support the view entertained by 
 Milne-Edwards and Haime namely, that we have to deal 
 in Trachypora with composite corals, the corallites of which 
 are sunk in a general ccenenchyma. Thin sections, however, 
 render it abundantly clear that this is not the case, but that the 
 thickened interstitial tissue between the actual tubes of the 
 corallites is only due to the deposition of delicate concentric 
 laminae of sclerenchyma round the visceral chambers, thus more 
 or less extensively obliterating the true walls. The corallites 
 are therefore really in close contact, and a true ccenenchyma 
 is wanting. It may further be noted that there exists in the 
 present species a kind of undulating median partition (PI. 
 V., fig. 4 c), which seems to separate the corallites on opposite 
 sides of the frond, or to mark the line along which the four 
 longitudinal rows of corallites meet centrally. 
 
 As regards other points of structural importance, tabulae are 
 very sparsely developed, and are not always detectable ; though 
 there can be no doubt of their general existence. Septa appear 
 to be wanting, so far as my observations go. Lastly, I have 
 not succeeded in demonstrating the existence of mural pores 
 to my own satisfaction ; but they are asserted to be present by 
 Dr Rominger, and I entertain no doubt as to the correctness of 
 his observations on this point. 
 
 Formation and Locality. Rare in the Hamilton formation 
 (Devonian) of Arkona, Ontario. 
 
GENERA OF FA VOSITW^. 1 1 1 
 
 Genus VERMIPORA, Hall, 1874. 
 (Twenty-sixth Annual Report on the State Cabinet of New York, p. 109.) 
 
 Professor Hall defines this genus as follows : " Bryozoum 
 growing in ramose branches, which are composed of small cell- 
 tubes growing upon one another side by side, without inter- 
 tubular or cellular substance, and destitute of rays or trans- 
 verse partitions within the tubes. Tubes diverging from the 
 centre of the branch, gradually diverging, and opening upwards 
 on the exterior surface ; each tube forming the apex of the 
 branch at the time of its origin, and giving place to succeeding 
 cells in its diverging outwards." 
 
 More recently, Dr Rominger has published the following 
 definition of Vermipora, Hall, (Rep. Foss. Cor. of Michigan, p. 
 68, 1876): 
 
 " Ramified twigs, composed of contiguous, sub - parallel, 
 cylindrical tubules, multiplying by lateral gemmation, slowly 
 diverging in their parallel ascending course from a central 
 imaginary axis, and becoming disjunct near their, peripheral 
 ends, which project on the surface as single proboscidal 
 siphuncules. Tubes intersected by remote transverse dia- 
 phragms, and connected by lateral pores. Vertical radiating 
 crests not observed." 
 
 To the above generic diagnosis Dr Rominger adds the fol- 
 lowing remarks : "Mr Hall places these forms with the Bryozoa, 
 and gives of their structure a description different from mine. 
 He has overlooked the principal Favositoid characters of the 
 tubes, diaphragms and lateral pores ; but I think these organs 
 can be found in his specimens as well as in those I have under 
 consideration." 
 
 Obs. Not having had the opportunity of personally examin- 
 ing any unquestionable examples of this genus, and having no 
 knowledge of its microscopic structure, it is impossible for me 
 to supply any data which might serve to clear up the discrep- 
 ancies between the generic diagnoses given by Hall and 
 
ii2 TABULATE CORALS. 
 
 Rominger, as above quoted. Judging, however, from Dr 
 Rominger's figures (loc. cit., PI. XXIV.), and accepting the 
 general accuracy of his observations as regards the presence of 
 tabulae and mural pores, it appears impossible to doubt that we 
 have to deal in Vermipora^ Hall, with a true Favositoid coral, 
 and not with a Polyzoan. In fact, Vermipora would not 
 appear to be structurally separable from Favosites, except by 
 the disjunct condition of the tubes towards their superficial 
 terminations the limited development of the tabulae and the 
 irregular distribution of the mural pores being features of minor 
 importance, and being, perhaps, not always present. 
 
 Though I have not had access to any American specimens 
 which I could unhesitatingly refer to the present genus, my 
 friend Dr Lindstrom has kindly sent me some examples of a 
 small coral from the Upper Silurian of Gotland, with the label 
 Favosites clausus, n. sp., which appear to me to be unques- 
 tionably congeneric with Vermipora, Hall. I shall therefore 
 proceed to briefly describe the structure of these under the 
 name of Vermipora clausa, Lindst., sp. ; and I will only add 
 here, that I am inclined to think it very probable that in reality 
 the genus Vermipora, Hall, is identical with the previously- 
 described Fletcher ia of Edwards and Haime. The latter 
 genus is, however, stated to increase by calicinal gemmation, 
 and to be destitute of mural pores ; and as I have had no 
 opportunity of examining any specimens of the type -species 
 (F. tubifera, E. and H.), I shall at present leave it in the 
 position to which it was assigned by the distinguished French 
 palaeontologists, and also by Professor Martin Duncan viz., in 
 the immediate neighbourhood of Syringopora.^ 
 
 1 It may be observed that there is some resemblance in external appearance 
 between Vermipora and some of the corals which have been referred to Anloporaj 
 and it does not seem impossible that such species of the latter as the A. spicata 
 of Goldfuss (Petref. Germ., p. 83, PI. XXIX., fig. 3), may prove on microscopic 
 examination to belong to the Favositida, and to be referable to Vermipora, Hall. 
 
GENERA OF FAVOSITID^E. 113 
 
 Vermipora clausa, Lindstrom, sp. 
 (PL VI., figs, i- 1 b.) 
 
 Spec. Char. Corallum forming small sublobate or subramose 
 masses, composed of nearly cylindrical corallites, which diverge 
 from an imaginary central axis. Centrally the corallites are in 
 close contact, and are rendered subpolygonal by mutual com- 
 pression ; but as they diverge outwards, they become, as a 
 general rule, more or less completely free, each being enclosed 
 by its proper wall. Diameter of the corallites about half a line, 
 the intercalated younger tubes of all sizes below this. Walls 
 thick, perforated at all points where the corallites are in con- 
 tact, by numerous irregularly-distributed, circular mural pores. 
 Septa well developed, in the form of radiating spines. Tabulae 
 well developed, complete, mostly horizontal, or curved with 
 their convexities downwards. 
 
 Obs. As before said, I am indebted to Dr Lindstrom for 
 examples of this species, with the label of Favosites clausus ; 
 and I presume that it is a portion of a specimen of this form 
 which he has figured in a paper on certain Zoantharia Rugosa 
 in the ' Ofversigt Vetenskaps- Akademiens Forhandlingar ' for 
 1856, PI. XXXI., fig. 14, under the name of Fletcheria claitsa. 
 I have not access, however, to the original of this paper, and 
 do not know if Dr Lindstrom has published any full description 
 of the species. 
 
 In general appearance the corallum of Vermipora clausa 
 might well be taken for a small dendroid Favosites, which 
 has a tendency to assume rather a lobed than a truly branched 
 character. The largest specimen I have is about ten lines in 
 length and five lines in its greatest width. The internal struc- 
 ture is also precisely that of Favosites proper ; and the only 
 point which justifies generic separation is to be found in the 
 fact that the tubes invariably become more or less cylindrical 
 and more or less completely free as their mouths are ap- 
 proached (PI. VI., fig. i). In the amount of this freedom, 
 however, there is considerable difference in different speci- 
 
 H 
 
n 4 TABULATE CORALS. 
 
 mens. In some examples the corallites, though still retaining 
 their cylindrical form, are very nearly in contact to their 
 calices ; whereas in others the tubes become completely dis- 
 junct long before their mouths are reached. In all cases, 
 however, the corallites are in close contiguity in all the cen- 
 tral portions of the skeleton ; and here their walls are always 
 perforated by irregularly distributed mural pores, the condition 
 of parts being, therefore, precisely the same as in Favosites. 
 The walls of the corallites, though moderately stout, are not 
 thickened by a conspicuous deposit of sclerenchyma, as in 
 Pachypora; while the calices are rounded, and often slightly 
 oblique, smaller ones being intercalated among those of aver- 
 age dimensions. Dr Lindstrom has noticed the fact that the 
 calices are occasionally closed by an opercular growth ; and the 
 exterior of the wall in the free portions of the tubes exhibits 
 numerous fine encircling striae. Transverse sections (PL VI., 
 fig. i a) show that the tubes in the centre of the corallum are 
 subpolygonal, with moderately thick walls, the lines of division 
 between them always remaining quite distinct. At the same 
 time, well-developed spiniform septa are brought into view. 
 Longitudinal sections (PI. VI., fig. i 6) precisely resemble 
 those of a Favosites, exhibiting septa and mural pores, along 
 with well-developed complete tabulae, which may be horizontal, 
 or may be curved with their convexity downwards. 
 
 Formation and Locality. Upper Silurian, Gotland, Coll., Dr 
 Gustav Lindstrom. 
 
 Genus ROMINGERIA, Nicholson. 
 
 Ouenstedtia, Rominger, Fossil Corals of Michigan, p. 70, 1876. 
 [Non Quenstedtia, Morris and Lycett, 1854.] 
 
 Gen, Char. Corallum lax, spreading ; resembling Aulopora 
 in its general appearance, but only attached basally, and free 
 throughout the greater part of its extent. Corallites cylindri- 
 cal, annulated, multiplying by lateral gemmation, and typically 
 producing new tubes in umbellate whorls or verticils, which 
 
GENERA OF FAVOSITID^E. 115 
 
 are placed at short intervals. Where their walls are in contact, 
 their visceral chambers are placed in communication by means 
 of mural pores. Tabulae complete, remote, apparently not dis- 
 tinctly infundibuliform. Septa represented by vertical rows of 
 spinules. 
 
 Obs. The type of this genus is the singular coral described 
 by Billings under the name of Aulopora umbellifera (fig. 19), 
 from the Corniferous Limestone of North Am- 
 erica. It was provisionally left by Billings, and 
 subsequently by myself, in the genus Aulopora, 
 upon the ground that its internal structure was 
 imperfectly known, but both of us stated that 
 it would probably prove to be the type of a new 
 genus. At a later date Dr Rominger succeeded 
 in establishing the important fact that mural Fi s- T 9- Portion 
 
 of the corallum of 
 
 pores are present in this species, and he there- Romingeria um- 
 fore properly removed it to the family of the 
 
 ) and raised it to the rank of a genus ferous Limestone 
 under the name of Quenstedtia. This designation natU rai size. 
 would of course have been retained by me but 
 for the fact that it has, unfortunately, been employed as early 
 as 1854, by Morris and Lycett, for a genus of Lamellibranchiate 
 Molluscs. Under these circumstances, I have great pleasure in 
 proposing for the genus the title Romingeria, in honour of one 
 who has so largely contributed to the elucidation of the fossil 
 corals of North America. 
 
 In many respects Romingeria is a type of special interest, as 
 affording us a transitional link between the families of the Favo- 
 sitida and the Syringoporidcz. It differs from Aulopora, to which 
 it was originally referred, by its erect mode of growth, in . the 
 disposition of the branches (as a rule) in successive verticils, and 
 more especially in its perforate walls. In general habit it does 
 not differ much from some species of Syringopora ; and if we 
 imagine its mural pores to be converted into hollow connecting 
 processes, it would be difficult or impossible to separate it from 
 this genus. The existence, however, of mural pores, as first 
 
n6 TABULATE CORALS. 
 
 demonstrated by Rominger, proves that it is properly referable 
 to the Favositidte> among which its true place would seem to be 
 in the neighbourhood of Vermipora, Hall. It differs from the 
 latter, in fact, principally by the lax spreading mode of growth 
 of the corallum, and by the much greater extent to which the 
 corallites are disconnected from one another. 
 
 Dr Rominger has described a species from the Niagara Group 
 of North America (loc. cit., p. 71); but I am only acquainted 
 personally with the type-species, R. umbellifera, Bill., of which 
 I subjoin a short description. I regret, however, that the state 
 of preservation of my specimens is such owing to silicifica- 
 tion that I have been unable to procure satisfactory micro- 
 scopic sections, and that I can therefore merely give such 
 characters as can be learned by the ordinary methods of 
 examination. 
 
 Romingeria umbellifera, Billings, sp. 
 (Fig. 19.) 
 
 Aulopora timbellifera, Billings, Canad. Journ., new sen, vol. iv. p. 119, 
 
 fig. 21. 
 ,, umbellifera, Nicholson, Report on the Palaeontology of Ontario, p. 
 
 43, PI. VI., fig. 4 (poor figure). 
 Quenstedtia umbellifera, Rominger, Rep. Foss. Cor. Michigan, p. 70, PL 
 
 XXXIIL, fig. 3. 
 
 Spec. Char. Corallum erect, lax, spreading, of cylindrical 
 corallites, with a thick annulated wall, adorned with fine en- 
 circling striae. Diameter of the corallites about one line. The 
 primary stems remain undivided for a distance of a quarter of 
 an inch or more, and then give origin to a cluster of corallites 
 in an umbellate manner, one or more of these proceeding to 
 proliferate in a similar manner, and at a similar interval, and 
 the process being repeated till a loosely fasciculate corallum is 
 produced. The number of corallites in a single verticil varies 
 from five or six to as many as ten or twelve, and they are at 
 first closely in contact with one another, the union of their 
 walls often extending to a distance of two or three lines from 
 
GENERA OF FAVOSITID^E. 117 
 
 the point of origin from the parent tube. Ultimately, they be- 
 come more or less completely free radiating outwards, like the 
 spokes of a wheel and one or more are continued beyond the 
 general circle of the whorl to give rise to a new umbel. Walls 
 thick, the visceral chambers of the corallites, where the latter 
 are in contact, being placed in connection by distinct mural 
 pores (Rominger). Tabulae remote, complete, so far as ob- 
 served horizontal. Septa represented by from six to ten 
 vertical rows of strong spinules. 
 
 Obs. I have little to add to the above specific diagnosis, 
 which embodies all the important characters which I can 
 gather from an examination of the specimens in my possession. 
 The existence of mural pores cannot be determined from any 
 of my examples, but Dr Rominger's figures (heliotypes) prove 
 their presence beyond all question. I think it quite likely that 
 Dr Rominger is correct in regarding Aulopora cornuta, Bill. 
 (Can. Journ., new ser., vol. iv. p. 1 18, fig. 20), as really founded 
 upon fragments of the present species. I have, however, vari- 
 ous specimens which seem to belong to Aulopora cornuta as 
 regards their general characters, but which agree with Aulopora 
 proper in being parasitic ; so that I must at present leave the 
 identity of this form with Romingeria umbellifera an open 
 question. 
 
 Formation and Locality. Rare in the Corniferous Limestone 
 (Devonian) of Port Colborne, Ontario. 
 
 Genus ALVEOLITES, Lamarck, 1801. 
 (Syst. des Anim. sans Vert., p. 375.) 
 
 Gen. Char. Corallum massive, incrusting, or ramose, com 
 posed of contiguous compressed corallites, which possess thin 
 walls, and open obliquely upon the surface by subtriangular or 
 semilunar calices. Septa sometimes obsolete, but often present 
 in the form of longitudinal rows of spinules, which may be 
 equally developed, or may be reduced to a single, double, or 
 
n8 TABULATE CORALS. 
 
 treble row by the suppression of the others. Tabulae well 
 developed, complete. Mural pores generally few in number, 
 of large size, and irregular in their distribution. 
 
 Obs. There is no genus in the entire series of the Favo- 
 sitida which presents greater difficulty than the present one, 
 as regards its satisfactory definition and separation from allied 
 types. So much so is this the case, that a strong disposition 
 has been shown by some of our most distinguished palaeontolo- 
 gists to reject the genus Alveolites altogether, and not without 
 reason, since it is certain that the forms which have at various 
 times been included under this name are of very different affin- 
 ities. The difficulties which environ this subject have been 
 elsewhere discussed at some length by Mr R. Etheridge, jun., 
 and myself (Journ. Linn. Soc., vol. xiii. p. 353, 1877); and I 
 shall avail myself largely of the memoir just referred to in what 
 follows. Since this paper was written, however, I have been 
 able to obtain much additional material throwing light upon the 
 genus, and am therefore able to speak more decidedly upon 
 some points which at that time appeared doubtful, as well as to 
 modify in some particulars the opinions therein expressed. 
 
 The genus Alveolites was originally founded by Lamarck in 
 the first edition of the ' Systeme des Animaux sans Vertebres ' 
 (published in 1801), p. 375, for the reception of a single Devo- 
 nian species which he described under the names of A. subor- 
 bicularis and A. escharoides, and for which the former title has 
 been subsequently retained. The original definition is, " Poly- 
 pary stony, thick, globular, or hemispherical, formed of numer- 
 ous concentric layers, which are superimposed one upon the 
 other, each layer formed by the union of alveolar, subtubular, 
 prismatic, contiguous cellules [or tubes], forming a network on 
 the surface." In the Hist. Nat. des Anim. sans Verteb. (pub- 
 lished in 1816), vol. ii. p. 184, the same definition is given with 
 very slight alterations, the principal change being that the genus 
 is now made to include incrusting forms. In the second edition 
 of Lamarck's Hist. Nat. des Anim. sans Verteb. (published in 
 1836), the portion relating to the corals was revised by Milne- 
 
GENERA OF FAVOSITID^. 119 
 
 Edwards, and the genus Alveolites is defined as follows (vol. ii. 
 p. 285) :- 
 
 " Corallum stony, sometimes incrusting, sometimes free and 
 massive, formed of numerous layers which are concentrically 
 superimposed upon one another, each layer composed of tubu- 
 lar, alveolar, prismatic cellules, which are somewhat short, and 
 form a network on the surface." Four species of the genus 
 were recognised by Lamarck, of which A. suborbicularis and A. 
 escharoides have been subsequently united with one another. 
 A. madreporacea is stated by Milne- Ed wards to be a Pocillo- 
 pora, and A. incrustans appears to be a Polyzoon. To the 
 above four species Milne- Edwards added, in the work just 
 quoted, four others, of which A. tubiporacea and A. millc- 
 poracea appear to be referable to Favosites ; A. clavata may 
 perhaps be a Chcetetes ; and A. infundibulifera was afterwards 
 placed by Edwards and Haime in a new genus under the 
 name of Rcemeria. 
 
 Without taking up time by discussing the views entertained 
 as to the characters of the genus Alveolites, and the different 
 forms referable to it, by Goldfuss, De Blainville, Michelin, 
 Steininger, D'Orbigny, and other well-known palaeontologists, 
 we may pass on to consider the opinions expressed by Milne- 
 Edwards and Jules Haime in their great works on the fossil 
 corals. In the Introduction to the ' Monograph of the British 
 Fossil Corals' (Palaeontographical Society, 1850, p. Ix), these 
 distinguished authorities place the genus Alveolites in the group 
 of the Favositidse proper, characterised by the presence of well- 
 developed tabulae, the existence of mural pores, and the rudi- 
 mentary condition of the septa. They define the genus as 
 possessing a " corallum composed of superposed strata of 
 corallites very similar to those of Favosites, but much shorter, 
 and terminated by an oblique semicircular or subtriangular 
 calice, the edge of which projects on one side." The type- 
 species of the genus is A. spongites, Steininger ( = A. suborbi- 
 .cularis, Lamarck). In their ' Polypiers Fossiles des Terrains 
 Paleozoiques ' (p. 254), the same authors in the succeeding year 
 
iso TABULATE CORALS. 
 
 redefine Alveolites as follows: " Corallum forming a convex 
 or dendroid mass. Calices oblique, subtriangular, or semi- 
 circular, presenting interiorly a longitudinal protuberance which 
 is opposed to two other smaller protuberances. These emi- 
 nences appear to represent the primary septa, and no other 
 traces of the septal apparatus can be detected. The walls are 
 simple, well developed, pierced with a small number of mural 
 pores. The tabulae are complete and horizontal." After 
 giving a history of the genus, the authors just quoted remark 
 that the elongated teeth or eminences above alluded to consti- 
 tute the most remarkable feature of the genus Alveolites, and 
 that they are to be regarded as so many primary septa, the 
 other three which form the normal cycle of six being aborted. 
 They further add that one of these three septal teeth is always 
 more pronounced than the other two, and that these latter may 
 be wholly wanting. 
 
 In the ' Histoire Naturelle des Coralliaires ' (vol. iii. p. 263, 
 1860), Milne - Edwards makes the following remarks as to 
 Alveolites: "The most striking character of Alveolites is fur- 
 nished by the septal system, which is represented by three teeth 
 or vertical projections one situated on the inside face of the 
 outer lip of the calice, the others opposite the preceding, upon 
 the inner lip of the corallite, and sometimes rudimentary. The 
 calices are oblique, subtriangular, or subhemispherical. Walls 
 simple, well developed, and pierced by a small number of 
 pores. Tabulae complete and horizontal. . . . The elon- 
 gated teeth or vertical projections which we see in the interior 
 of the visceral chambers of the corallites form the most peculiar 
 character of Alveolites, and recall the three principal septa 
 which characterise the genus Heteroccenia amongst the As- 
 trseidse. . . . It is also worthy of note that one of the septal 
 projections is more developed than the other two, and often it 
 alone may exist." 
 
 In briefly analysing the above, It will be obvious, in the first 
 place, that Lamarck's definition of the genus Alveolites does 
 not contain a single character which would at the present day 
 
GENERA OF FAVOSITID&. 121 
 
 be regarded as of generic importance at all ; so that the ulti- 
 mate existence of the genus will depend upon whether the type- 
 species, A. suborbicularis, Lam., can be shown to possess char- 
 acters which separate it generically from allied forms. In the 
 second place, the various definitions given by Milne-Edwards 
 and Haime yield, upon collation, the following characters as 
 essentially distinctive of the genus Alveolites as understood 
 by them : (i.) The corallites are furnished with lamellar walls, 
 and are not united by any ccenenchyma. (2.) The visceral 
 chamber is traversed by well - developed horizontal tabulae. 
 (3.) Mural pores, comparatively large and few in number, 
 are present. (4.) The corallites are oblique, shorter than in 
 Favosites, and terminated by oblique, semilunar, or subtrian- 
 gular calices. (5.) There exist in the interior of each corallite 
 three elongated teeth, which represent the primary septa, and 
 of which one is always larger than the others, and may be the 
 only one present. (6.) The corallites are arranged in the mas- 
 sive and incrusting forms in superimposed layers. 
 
 Alveolites suborbicularis, Lam., the type -species, possesses 
 all the above-mentioned characters, and is therefore, to begin 
 with, clearly a member of the Favositidas proper. In order, 
 however, to establish the validity of the genus Alveolites, it is 
 further necessary to prove that A. suborbicularis is generically 
 separable from Favosites ; and there are only two of the above- 
 mentioned characters namely, the obliquity of the calices and 
 the presence of septal teeth which require special consideration 
 in this connection. Moreover, even if the generic distinctness 
 of A. suborbicularis and immediate allies be satisfactorily estab- 
 lished, there still remain various forms more or less resembling 
 this, which nevertheless differ considerably from it in minute 
 structure, and which must therefore be referred to different 
 groups. 
 
 To the above remarks, taken from the paper already referred 
 to, was added a brief account of the principal types of structure 
 which are recognisable in the various forms which have been 
 at different times included under Alveolites by different palaeon- 
 
122 TABULATE CORALS. 
 
 tologists, and which externally resemble this genus more or less 
 closely. In most of the views therein expressed, I am still quite 
 willing to concur, but the further observations which I have 
 made enable me to state these views in a more definite form 
 than was at that time possible, and also to make some modifi- 
 cations in them. The results, then, of my inquiries, combined 
 with those formerly arrived at by my colleague and myself, 
 are briefly as follows : 
 
 1. Taking Alveolites sub orbicular is, Lam., as the type of 
 Alveolites, the genus may be usefully retained, but the pres- 
 ence of septal teeth must be abandoned altogether as a generic 
 distinction, and we must include under the same head forms 
 such as A. Labechei, E. and H., and A. Goldfussi, Bill., which 
 have numerous septa, or in which the septa are obsolete. On 
 this view, Alveolites will include forms which agree with Favo- 
 sites in all essential characters, save only the possession of 
 oblique calices and narrow compressed or triangular coral- 
 lites. I fully admit that the characters just mentioned, when 
 standing alone, cannot be strictly regarded as of generic value, 
 and that the most rigidly scientific course would be to merge 
 Alveolites in Favosites. This course, however, would render 
 the genus Favosites an extremely unmanageable one, and upon 
 the ground of practical convenience I prefer separating Alveo- 
 lites by means of the readily recognisable character of the reclined 
 corallites and oblique calices. All the species thus placed in 
 Alveolites agree with one another and with Favosites proper in 
 having thin-walled corallites, without any excessive thickening 
 of the terminations of the tubes, and they are thus distin- 
 guished both from Pachypora and from Coenites, with which 
 they are otherwise closely allied. I include in this group 
 Alveolites sub orbicular is, Lam., A. Labechei, E. and H., A. 
 Goldfussi, Bill., A. Indianensis, Rom., and all forms related 
 to these. 
 
 2. Some of the forms which have been referred to Alveolites 
 are properly placed under the genus Pachypora, Lindst., as 
 shown by the thickening of the interior of the tubes by a dense 
 
GENERA OF FAVOSITID^E. 123 
 
 secondary deposit of sclerenchyma. As has previously been 
 pointed out, this is the case with the so - called Alveolites 
 Fischeri, Bill., and A. frondosa, Nich. ; and I have no doubt 
 that other forms, both of the expanded and ramose type, will 
 ultimately prove to be referable to Pachypora, rather than 
 to Alveolites as here defined. 
 
 3. The forms grouped under C&nites, Eichw., so far as pro- 
 perly placed under this head, may be distinguished from 
 Alveolites by the form of the calices, but more especially by 
 the great thickening of the interior of the tubes in the neigh- 
 bourhood of their mouths. As will subsequently be seen, 
 therefore, Ccenites bears the same relation to Alveolites that 
 Pachypora does to Favosites, while it has some special features 
 in addition. 
 
 4. The forms which have been described as Alveolites septosa, 
 Flem., and A. depressa, Flem., are closely allied to Chcztetes 
 radians, Fischer, and must be removed to the genus Chtetetes. 
 
 Returning now to the genus Alveolites as here defined, the 
 form of the corallum appears to be very variable. Alveolites 
 sub orbicular is, Lam., the type of the genus, appears really to 
 be almost always in the form of irregular masses which are 
 formed of concentrically disposed layers which have grown 
 parasitically round some foreign body. In other forms, how- 
 ever, such as A. Labechei, E. and H., and A. Goldfussi, Bill., 
 the form of the corallum is that of a flattened, sometimes gib- 
 bous expansion, which is covered below by a wrinkled epitheca, 
 and only exhibits calices upon its upper surface. Other forms, 
 again, such as A. Rcemeri, Bill., are dendroid ; but the various 
 ramose corals which have been included under Alveolites will 
 require to be subjected to a careful microscopic examination 
 before their true affinities can be positively asserted. Lastly, 
 so far as I have seen, no true Alveolites, in the sense here 
 understood, has the form of an erect frondose expansion, 
 attached basally, and having its free surfaces entirely covered 
 with calices. 
 
i2 4 TABULATE CORALS. 
 
 In the most typical species of Alveolites, the corallites are 
 excessively oblique to the principal plane of the corallum, 
 those which open on the circumference of the mass most so, and 
 those in its centre least. A. suborbicularis, Lam., offers the 
 extreme type of this condition, while A. Indianensis, Rom., 
 though an unquestionable Alveolites, presents the minimum 
 amount of obliquity of its tubes. It has been pointed out by 
 Lindstrom that A. Fougtii, E. and H., primitively possesses 
 erect corallites, which only become reclined in the course of 
 growth ; and upon this ground this high authority has placed 
 the species in Favosites. Upon the whole, however, though 
 formerly disposed to adopt the same view, I think it safer to 
 go by the adult characters of the corallum, which would seem 
 to place this curious transitional form in Alveolites. 
 
 Owing, also, to the obliquity of the corallites, the calices in 
 Alveolites open obliquely upon the surface, one lip being shorter 
 than the other, and the aperture being more or less transversely 
 elongated, its shape being in general subtriangular, semilunar, 
 or subrhomboidal. 
 
 The walls of the corallites in Alveolites are invariably thin, 
 as conclusively shown by thin sections ; there is no marked 
 thickening due to the deposition of concentric lamellae of scler- 
 enchyma in their interior, nor are the tubes notably, or as a 
 rule at all, expanded towards their mouths. All forms re- 
 sembling Alveolites in appearance, but with abnormally thick- 
 ened walls, must find a place either in Pac/iypora, Lindst., or 
 in Ccenites, Eichw. 
 
 The mural pores are usually few in number, and of compara- 
 tively large size ; but it is certain that this character cannot be 
 used as one of generic value, precisely the same feature occur- 
 ring in Pachypora. 
 
 The septal system varies much in its development in Alveo- 
 lites. As has been seen, Milne-Edwards and Haime regarded 
 the presence in the interior of each corallite of three elongated 
 teeth or septal ridges, which may be reduced to one, and which 
 represent the septa, as the leading character of the genus. I 
 
GENERA OF FAVOSITID^E. 125 
 
 am, however, quite satisfied that this view is untenable, and 
 that the condition of the septa is too variable to allow of its 
 being used as a generic character. A. suborbicularis, Lam., 
 seems often to possess such a single septal ridge in the interior 
 of each corallite (see fig. 20, and PI. VI., fig. 2) ; but an exami- 
 nation of a number of well-preserved specimens from the Eifel 
 has convinced me that it is excessively difficult to detect this 
 feature even in the most perfect examples, and that it is seem- 
 ingly really not invariably present, since it is only occasionally 
 that such a structure can be made out by thin sections, so far as 
 I have seen. It may be freely conceded, however, that certain 
 species have the septa reduced to one or three longitudinal 
 ridges, though no more than a specific value can be assigned 
 to this. On the other hand, A. Labechei, E. and H., though 
 stated by Edwards and Haime to possess a " slightly devel- 
 oped" or "very indistinct" septal ridge, like that of A. subor- 
 bicularis, can be conclusively shown by microscopic sections to 
 possess numerous vertical rows of septal spines (PI. VI., figs. 
 3 and 3 a) precisely similar in their characters to those of F. 
 Hisingeri, E. and H., and other species of Favosites. The same 
 feature is equally observable in some other species. In certain 
 types, again, such as A. Goldfussi, Bill. (PI. VI., fig. 4), the 
 septa appear to be entirely obsolete, no traces of their existence 
 being observed in thin slices. Upon the whole, then, we must 
 regard the development of the septa in Alveolites as quite 
 variable, and as affording characters of no more than specific 
 importance. 
 
 Lastly, the tabulae in Alveolites are always well developed, 
 and are complete and essentially horizontal. These structures, 
 however, present no features of special importance. 
 
 The known species of Alveolites, as here defined, are confined 
 to the Upper Silurian and Devonian periods ; and the two 
 species which I shall select for brief description as illustrating 
 more fully the characters of the genus are A. sub orbicular is, 
 Lam., and A. Labechei, E. and H. 
 
126 TABULATE CORALS. 
 
 Alveolites suborbicularis, Lamarck. 
 (PL VI., figs. 2-26.) 
 
 Alveolites suborbicularis, Lamarck, Hist, des An. sans Vert., vol. ii. p. 186, 
 1816. 
 
 escharoides, Lamarck, ibid., p. 186. 
 Calanwpora spongites, var. tuberosa, Goldfuss, Petref. Germ., p. 80, PI. XXVIII., 
 
 figs, i a-i e (caet. exclusis), 1829. 
 
 Favosites spongites (?), Phillips, Pal. Foss., p. 16, PL VIIL, fig. 23, 1841. 
 Alveolites suborbicularis, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 
 p. 255, 1851, and Brit. Foss. Cor., p. 219, PL XLIX.,figs. i and i a, 1853. 
 
 Spec. Char. Corallum forming masses of considerable size 
 and variable form, consisting of concentrically superposed layers, 
 attached parasitically to some foreign body, and having an 
 irregularly elevated surface. Corallites very oblique, com- 
 pressed, mostly subtriangular, with a long convex and two 
 short concave sides, but very variable in form, though never 
 regularly polygonal or cylindrical. Long diameter of the tubes 
 about one-third of a line, transverse diameter about one-sixth 
 of a line. Walls moderately but not excessively thick, not in- 
 crassated towards the terminations of the tubes, and pierced by 
 few remote mural pores. Septa represented only by a single 
 longitudinal ridge, which does not appear to be constantly 
 present. Tabulae numerous, close-set, horizontal, complete. 
 
 Obs. The specimens from which the above description is 
 taken were collected by myself in the Eifel, and agree in all 
 respects with the figures given by Goldfuss (Petref. Germ., PI. 
 XXIX., figs, i a- 1 e\ Milne- Edwards and Haime add figs \f- 
 i h of the same plate, but I think these belong to a different 
 species). These figures give an excellent idea of the general 
 form and appearance of this species ; and I have not, therefore, 
 thought it necessary to give an illustration of one of my own 
 specimens. So far as I can judge at present, I think that the 
 name of A. suborbicularis will have to be restricted to the 
 specimens which have the habit of forming irregularly gibbous 
 masses, composed of successive concentric strata enveloping 
 
GENERA OF FAVOSITID&. 127 
 
 some central foreign body. It is not that any particular stress 
 can be laid upon the mode of growth per se ; but so far as my 
 observations have gone as regards this species, this peculiar 
 habit is only found in specimens which have a special internal 
 structure ; and, under these circumstances, it becomes a charac- 
 ter of specific value. On the other hand, there occur along with 
 the preceding many specimens which form flattened or sub- 
 hemispherical expansions, having their under surface covered 
 by a wrinkled epitheca, attached to some foreign object by a 
 pedunculate base, having the calices confined to the upper sur- 
 face only, and not exhibiting any composition of the corallum 
 out of concentric layers. Specimens of this type in other re- 
 spects nearly resemble A. suborbicularis, Lam., and they might 
 be easily, and I believe sometimes have been, confounded with 
 the latter. So far as I have yet examined such specimens, 
 however, I find them to differ from the encrusting and lami- 
 nated specimens which constitute the true A. suborbicularis, 
 Lam., in various points of their internal structure, and especially 
 in the possession of numerous unusually strong spinose septa. 
 
 The only points in the anatomy of A. suborbicularis to which 
 I need draw attention are the condition of the septa and the 
 tabulse. According to Milne-Edwards and Haime, the outer 
 or under side of each of the calices 
 " bears interiorly a small elongated 
 ridge, which appears to represent a 
 septum, and is placed opposite to a 
 small notch" (Brit. Foss. Cor., p. 219). 
 Such septal ridges have been well 
 figured by Goldfuss, and I have re- 
 produced his drawing in order to show 
 their character (fig. 20). I am not able 
 to assert, however, that I have sue- Fig. 20. Caikes of ^/zw/^j si>- 
 
 , , . , .1 i orbicitlaris, Lam., greatly en- 
 
 ceeded in detecting their presence by large d, showing the single septal 
 an examination with a lens of any of rid g e - Devonian, Eifei. (After 
 
 ' Goldfuss.) 
 
 the specimens in my possession, and I 
 
 think that little specific value can be attached to a character 
 
128 TABULATE CORALS. 
 
 so uncertain and so difficult of recognition. This opinion is 
 strongly supported by the appearances presented by tangential 
 sections (PI. VI., fig. 2 a). In these, the characteristic com- 
 pressed form and the moderately thick walls of the corallites 
 can be admirably observed ; but the single septal ridge above 
 alluded to can only be made out occasionally, and never, so far 
 as I have seen, in more than quite a small proportion of the 
 tubes. It does not seem, therefore, to be of constant occur- 
 rence, and no other traces of septa can be detected. 
 
 In longitudinal sections (PI. VI., fig. 2 b) the chief feature 
 observable is the abundance of the horizontal and complete 
 tabulae, no traces of septa being recognisable. 
 
 Formation and Locality. Abundant in the Devonian Lime- 
 stone of Gerolstein and Bensburg in the Eifel. I do not yet 
 feel certain if any of the specimens which I possess from the 
 Devonian limestones of Devonshire are really identical with 
 this species, though some certainly present a close resemblance 
 to it. None of the species of Alveolites from the Devonian of 
 North America that I have examined, or that have been figured 
 or described by other observers, seem to be referable to this 
 species. 
 
 Alveolites Labechei, Edwards and Haime. 
 (PL VI., figs. 3 and 3 a.) 
 
 Favosites spongites (pars), Lonsdale, in Murchison, Silurian Syst, PL XV., 
 
 figs. 8-8 b (caet. exclusis), 1839. 
 Alveolites Labechei, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 
 
 257. rtS 1 - 
 
 Labechei) Milne-Edwards and Haime, Brit. Foss. Cor., p. 262, PL 
 
 LXL, figs. 6-6 b, 1854. 
 Grayi, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 
 
 258, 1851, and Brit. Foss. Cor., p. 262, PL LXT.,figs. 2-2 a. 
 
 Spec. Char. Corallum massive, attached to foreign bodies 
 by one point of its base, and forming a flattened expansion 
 with a slightly convex or irregularly elevated surface, the upper 
 surface being occupied by calices, while the lower surface may 
 be in large part similarly occupied, or may be covered with a 
 
GENERA OF FAVOSITID^E. 129 
 
 concentrically-wrinkled epitheca. Average size of the corallum 
 from an inch or less up to three inches in diameter, with a 
 height of from five to fourteen lines. Corallites extremely 
 oblique, compressed, from one-third to one-half of a line in 
 their long diameter, and less than this in their short diameter. 
 Calices upon the upper surface very oblique, subtriangular, or 
 somewhat lozenge-shaped, usually bounded by one long and two 
 short curved margins ; upon the lower surface, where present, 
 usually less oblique, and often irregularly polygonal. Septa 
 numerous, in the form of pointed spines, which have a marked 
 upward direction, and extend into the visceral chamber to about 
 one-third of its diameter. Tabulse numerous, complete, hori- 
 zontal. Mural pores apparently comparatively numerous and 
 of no large size. 
 
 Obs. This is one of the most abundant of the corals of the 
 Wenlock Limestone of Britain. If the Devonian A. suborbicu- 
 laris, Lam., be considered, as has here been done, to include only 
 forms which grow into irregular masses composed of superposed 
 concentric strata of corallites, then the present species is easily 
 distinguished from it by the difference of its ordinary habit. It 
 forms flattened expansions, attached by a pedunculate base, and 
 usually having part of the lower (as well as the upper) surface 
 covered by calices. Sometimes almost the whole lower surface 
 is so occupied, but generally a portion seems to have been pro- 
 tected by an epitheca. In general form, therefore, A. Labechei, 
 E. and H., resembles the A. Goldfttssi, Bill., of the Devonian 
 of North America; but the latter is readily distinguished by the 
 much larger size of the calices and the total absence of septa 
 (PL VI., fig. 4). Milne-Edwards and Haime have separated 
 Alveolites Grayi from Alveolites Labechei, upon the ground that 
 " its calices are always larger, and are limited by walls that are 
 thicker in proportion to the size of the corallites." After a 
 careful examination, however, of both of these forms, I am 
 forced to come to the conclusion that they are not specifically 
 separable, the more especially as single specimens are not un- 
 common in which the calices have in parts the long diameter of 
 
1 30 TABULATE CORALS. 
 
 those assigned to A. Labechei (" somewhat more than one-third 
 of a line "), while in other parts the long diameter of these open- 
 ings is that of A. Grayi (" about half a line "). Moreover, thin 
 sections show that they agree with one another in their internal 
 structure, this exhibiting a feature unusual in the genus Alveo- 
 lites namely, a well-developed system of septa. These septa 
 are excellently seen by means of thin tangential and vertical 
 sections (PI. VI., figs. 3-3 a), and have the form of a circle of 
 radiating spines, of variable number (often ten or twelve), ex- 
 tending into the interior of the tubes, and sometimes reaching 
 nearly to the centre of the visceral chamber. In longitudinal 
 sections (PI. VI., fig. 3 a) these septal spines are seen to form 
 vertical rows, and to be generally markedly directed upwards, 
 or towards the mouths of the tubes. Owing to this latter fact, 
 they often look, when seen in transverse sections (PI. VI., fig. 3), 
 as if they were not actually connected with the wall of the tube. 
 Longitudinal sections show the presence of numerous complete 
 tabulae, and occasionally of mural pores, the latter seemingly 
 more numerous and smaller than is usual in Alveolites. Both 
 kinds of sections show that the walls of the corallites are in no 
 wise abnormally thickened, and A. Labechei, E. and H., is thus 
 shown to belong properly to Alveolites as here understood. 
 
 Formation and Locality. Abundant in the Wenlock Lime- 
 stone of Benthall Edge, and Dormington Quarry near Stoke- 
 Edith. Also in the Wenlock Limestone of Gotland. It has 
 not been hitherto detected in the corresponding formation of 
 the Niagara Limestone of North America, but species of the 
 same general type are abundant in the Devonian of Europe and 
 North America. 
 
 Genus CCENITES, Eichwald, 1829. 
 
 (Zool. Spec., t. i. p. 179.) 
 Limaria, Steininger, Mem. Soc. Geol. de France, t. i. p. 339, 1831. 
 
 Gen. Char. Corallum usually dendroid or frondescent, rarely 
 submassive. Corallites compressed, thin-walled in the centre of 
 
GENERA OF FAVOSITID^E. 131 
 
 the corallum, but immensely thickened in the neighbourhood of 
 their mouths by means of a dense secondary deposit of scleren- 
 chyma, the proper walls nevertheless always remaining distinct. 
 Visceral chamber reduced to a fissure in the vicinity of its termi- 
 nation, and opening upon the surface by a narrow transversely- 
 elongated slit-like calice, one lip of which carries two tooth-like 
 projections, which face a single similar tooth springing from 
 the opposite lip. Septa represented only by the calicine teeth 
 just spoken of. Tabulae well developed, complete, horizontal. 
 Mural pores moderately numerous, large-sized, irregularly dis- 
 tributed. 
 
 Obs. The genus Ccenites was originally founded by Eich- 
 wald (loc. ?.), and was subsequently described by him 
 (Lethaea Rossica, vol. i. p. 457) as comprising dendroid or 
 lamellar and encrusting corals, with semicircular or triangular 
 calices, provided with a single rudimentary septal ridge upon 
 their lower lips, the corallites being united by an abundant 
 " ccenenchyma." Milne-Edwards and Haime (Pol. Foss. des 
 Terr. Pal., p. 301) also suppose that a "ccenenchyma" is pre- 
 sent, and they describe the septal system as consisting typically 
 of three teeth, two on one margin of the calice and one on the 
 other. The same authors include the genus among the Pocil- 
 loporidcz, though they subsequently express a doubt whether it 
 should not rather be removed from the Actinozoa and placed 
 among fatPolyzoa (Brit. Foss. Cor., p. 276). Professor Martin 
 Duncan (Third Rep. on Brit. Foss. Cor. ; Rep. Brit. Ass., 
 1871, p. 130) also assumes the existence of a "ccenenchyma" 
 in Ccenites. Dr Lindstrom (Nagra Anteckningar om Anthozoa 
 Tabulata, Ofversigt af Vetensk. Akad. Forhandl., 1873) con- 
 siders that Ccenites may possibly be referable to the Polyzoa ; 
 but, somewhat inexplicably, he regards Alveolites sub orbicular is, 
 Lam., and its allies as belonging to this genus. Mr R. Ethe- 
 ridge, jun., and myself pointed out (Journ. Linn. Soc., vol. xiii. 
 p. 361), from an examination of Ccenites orientalis, Eichw., that 
 probably there existed no true ccenenchyma in Ccenites, and in- 
 dicated that this generic name might need to be suppressed in 
 
i 3 2 TABULATE CORALS. 
 
 favour of Alveolites, Lam. Lastly, Dr Rominger (Foss. Corals 
 of Michigan, p. 43) placed the genus in the Favositidce, in the 
 immediate neighbourhood of Alveolites, from which he regards 
 it as differing only by " more conical stout-walled tubes of less 
 compressed and more rounded form in the central or basal parts 
 of the polyparia." 
 
 The true structure and affinities of Ccenites, Eichw., can be 
 determined with the greatest certainty by means of thin micro- 
 scopic sections ; and these show that the genus is not only not 
 Polyzoan in its relationships, but that it is in all respects pro- 
 perly referable to the Fdvo$itid& t standing upon the whole 
 nearer to Pachypora than to Alveolites. Thus, thin sections 
 show that the tubes are not only tabulate, but that they have 
 the more important feature of being placed in communication 
 with one another by means of a well-developed system of 
 " mural pores," which are precisely similar in all points of im- 
 portance to the pores of Favosites, and which only differ from 
 these in being irregularly distributed. Moreover, there is no 
 " c&nenchyma " present in the corals of this genus, as has been 
 generally supposed. On the contrary, the corallites (PI. VI., 
 fig. 5 a) are in close contact throughout their entire length, and 
 their walls are also everywhere quite distinct. In the centre 
 of the corallum the tubes have quite thin walls, and present 
 no feature by which they could be distinguished from the coral- 
 lites of a ramose Favosites. Just before reaching the surface, 
 however, each tube bends abruptly, often dividing at the same 
 time, and the wall for the rest of its course is immensely thick- 
 ened by a dense secondary deposit of sclerenchyma. In this 
 constriction of the visceral chamber near its mouth, the species 
 of Ccenites agree with those of Pachypora, Lindst. ; but in the 
 former the thickening is rigidly confined to a narrow external 
 band, and does not affect the internal parts of the corallum at 
 all ; whereas in Pachypora the thickening affects the tubes 
 throughout their entire length, and merely attains its maximum 
 as the mouth is approached. Furthermore, the corallites in 
 Pachypora are not markedly compressed or oblique, and are 
 
GENERA OF FAVOSITID^E. 133 
 
 equally thickened all round, so as to have their calices sur- 
 rounded by tumid margins of equal thickness, and mostly 
 rounded or subpolygonal in form. On the other hand, in Coenites 
 the thickening affects principally the upper aspects of the tubes ; 
 and hence the calices assume the form of long narrow slits or 
 fissures, the length of which greatly exceeds the width (PI. VI., 
 fig. 5). Lastly, in Pachypora there are usually numerous short 
 radiating septa, in the form of tubercles or spines. No struc- 
 tures, however, can be recognised in Coenites as representing 
 the septa in the actual visceral chamber itself below the thick- 
 ened portions of the tubes ; and the only traces of these organs 
 are to be found in the tooth-like projections of the margins of 
 the calices. These projections are generally three in number 
 two on one margin, and a single unpaired tooth opposite the 
 notch between these on the opposite margin ; but there may be 
 five of these teeth three on one margin, and two on the other. 
 The tabulae present no specially noticeable features, being well 
 developed and complete, though not very numerous, through- 
 out the central unthickened portion of the tubes. The differ- 
 ent species of Coenites will require careful revision, by the light 
 of microscopic sections, before they can be regarded as fully 
 established. 
 
 In its geological range, the genus is principally Upper 
 Silurian ; but species supposed to belong to it have been also 
 described from the Devonian formation. In the Upper Silurian 
 rocks the genus is found in Britain, Europe, and North America. 
 The species which I have selected as illustrative of the genus 
 are Coenites juniper inus, Eichw., and a form which I believe to 
 be the Coenites linearis of Edwards and Haime. 
 
134 TABULATE CORALS, 
 
 Coenites juniperinus, Eichwald. 
 (PL VI, figs. 5, 5 V). 
 
 C&nites juniperinus, Eichwald, Zool. Spec., vol. i. p. 179, 1829. 
 
 Limaria clathrata, Lonsdale, in Murchison's Sil. Syst., p. 692, PI. XVI., bis, 
 
 figs. 7, 7 a, 1839. 
 Coenites juniperinus, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 
 p. 301, 1851 ; and Brit. Foss. Corals, p. 276, PL LXV., figs. 4 and 4 a. 
 (Compare Limaria ramulosa, Hall, Pal. N.Y., vol. ii. p. 142, PL XXXIX., 
 
 fig. 4, 1852.) 
 
 Spec. Char. Corallum dendroid, of cylindrical dichotomous- 
 ly-dividing branches, the diameter of which is generally about 
 two lines. Corallites nearly vertical in the centre of the 
 branches, with thin walls, and about one-sixth of a line in 
 diameter ; gradually diverging in their upward course till they 
 reach a point from one quarter to half a line from the surface, 
 when they suddenly bend outwards, their walls being now 
 greatly thickened, and the visceral chamber reduced to a mere 
 slit. Calices fissure-like and elongated in the direction of the 
 transverse diameter of the branches, their long diameter about 
 one-third of a line ; the lower margin adorned with two pro- 
 minent teeth, while the upper margin carries a single tooth cor- 
 responding in position to the notch between the lower teeth. 
 Tabulae not very numerous, but well developed and complete. 
 Mural pores moderately numerous, circular, not excessively 
 large, irregularly distributed. 
 
 Obs. This well-known Upper Silurian form is readily dis- 
 tinguished by the external characters of the cylindrical branches, 
 and the long, transversely-disposed toothed calices (PI. VI., 
 fig. 5), which are not elevated above the general surface. The 
 fissure-like calices are generally separated from one another, in 
 a vertical direction, by interspaces varying from about one-fifth 
 to one-third of a line ; and they thus appear as if sunk in a 
 compact smooth ccenenchyma. In longitudinal sections (PI. 
 VI., fig. 5 a) this apparent coenenchyma is shown to be due to 
 a deposit of sclerenchyma within the tube of each corallite in 
 
GENERA OF FAVOSITID^E. 135 
 
 the neighbourhood of its mouth, this portion of the corallite 
 being in reality rather dilated than narrowed. The deposit of 
 secondary sclerenchyma seems, further, to be laid down almost 
 entirely on the upper aspect of each corallite in its interior, so 
 that the visceral chamber is reduced to a mere slit occupying 
 the lower side of the corallite. In the interior portions of the 
 branches the corallites are not thickened, but possess patulous 
 tube-cavities (PI. VI., fig. 5 a), which are intersected by remote 
 and complete tabulae, and are placed in communication by dis- 
 tinct mural pores. Transverse sections (PI. VI., fig. 5 b) not 
 only show the absence of secondary thickening in the walls 
 of the corallites in the interior of the corallum, but likewise 
 the compressed and subpolygonal form of the tubes in this 
 region. 
 
 Formation and Locality. Abundant in the Wenlock Lime- 
 stone of Dormington Quarry, Stoke-Edith. 
 
 Ccenites linearis, Edwards and Haime. 
 (PL VII., figs, i- 1 <?.) 
 
 Ccenites linearis, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 302, 
 1851 ; and Brit. Foss. Cor., p. 277, PI. LXV., fig. 3, 1854. 
 
 Spec. Char. Corallum usually in the form of a lamellar ex- 
 pansion, sometimes sublobate, rarely massive. Corallites from 
 a fifth to a fourth of a line in diameter, compressed, and pos- 
 sessing thin walls throughout the interior of the corallum. On 
 approaching the surface they bend more or less abruptly out- 
 wards, their upper walls being now greatly thickened by an 
 adventitious deposit of sclerenchyma, and their tube-cavities 
 reduced to a mere fissure. Calices in the form of long linear 
 slits, sometimes nearly straight, sometimes arcuate, which have 
 a length of about half a line, or rather less, with a width of not 
 more than about one-twelfth of a line. Tabulse remote, hori- 
 zontal, complete. Mural pores circular, of tolerably large size, 
 moderately numerous, irregularly distributed. Septa repre- 
 
I3 6 TABULATE CORALS. 
 
 sented by from three to five longitudinal ridges, which appear 
 to be confined to the thickened outer portions of the tubes, and 
 which form a corresponding number of teeth projecting into the 
 calice. Ordinarily there are two of these teeth on one lip of 
 the calice, and one on the other ; but there may be three teeth 
 on one lip and two on the other, or even more of these projec- 
 tions may be present. 
 
 Obs. I have some doubt as to the propriety of identifying 
 my specimens with Ccenites linearis, E. and H., which is de- 
 fined as follows (Brit. Foss. Cor., p. 277) : 
 
 " Corallum massive, convex, or subgibbose, and composed of 
 thin superposed layers. Calices closely set, not prominent, or 
 but very slightly so, linear, with their margin very obscurely 
 denticulated, about half a line broad, and one-twelfth in the 
 contrary direction." 
 
 My specimens agree with the above description in the linear 
 form of the calices, and in the dimensions of these apertures ; 
 but the calicine teeth are very well marked (in well-preserved 
 examples), and the corallum, though sometimes sublobate, 
 could certainly not be properly said to be " massive." The 
 great majority of the specimens which I refer here have the 
 form of thin lamellar or palmate expansions (PI. VII., fig. i), 
 two inches or more in width, with a thickness of a line and a 
 half to two lines. The corallites in the centre of the frond are 
 nearly or quite parallel with the flat surfaces of the latter, and 
 they diverge outwards to open either on one surface only, or 
 apparently more generally upon both surfaces. Sometimes, by 
 the superposition of several laminae, the corallum may attain a 
 thickness of four or five lines ; and the same dimensions are 
 sometimes reached when the corallum has the form of a broad 
 flattened or palmate stem. I have never seen any truly mas- 
 sive example. Upon the whole, however, considering the points 
 of likeness between the two, I think it safest to refer my 
 specimens to C. linearis ; E. and H., and to regard the speci- 
 men described by Edwards and Haime as probably excep- 
 
GENERA OF FA VOSITID^E, 137 
 
 tional, or as owing its apparently massive form merely to the 
 coalescence of a succession of crusts. 
 
 The calices of C linearis, E. and H., are very characteristic. 
 They appear as long linear slits (PL VII., figs, i-i 6), which 
 may be nearly straight, but are more commonly strongly curved, 
 and which have their margins toothed by a variable number of 
 septa (most generally two on one margin, and one on the other), 
 while they have the appearance of being embedded in a dense 
 compact ccenenchyma. The form of the calices accurately 
 expresses the form of the visceral chamber to a certain depth 
 (half a line to nearly one line) below the surface, and tangential 
 sections taken within this depth (PI. VII., fig. i c) show that 
 the tubes are still curved linear fissures, with denticulate mar- 
 gins, and surrounded by dense calcareous tissue. In the in- 
 terior of the corallum, on the other hand, the corallites appear 
 as thin-walled, subpolygonal, compressed tubes, with freely 
 open cavities. The internal structure, in fact, is precisely the 
 same as that already described as characterising C. juniperinus y 
 Eichw. Thus, sections taken at right angles to the flat surfaces 
 of the frond (PI. VII., fig. i d] show that the gently-diverging 
 and thin-walled tubes of the central area, on approaching a 
 point situated a line or less below the actual surface, suddenly 
 bend outwards, nearly at right angles to their former course. 
 They now dilate, but their central cavity, instead of under- 
 going a corresponding expansion, becomes now still further 
 restricted, and is reduced to a narrow linear chamber, which 
 occupies one side of the corallite, the whole of the remaining 
 space within the walls of the latter being occupied by a dense 
 secondary deposit of sclerenchyma. There is, however, no 
 true " ccenenchyma ; " and the appearance of such a structure 
 is only due to the deposition of this sclerenchyma in the 
 interior of the tubes, and its coalescence in contiguous coral- 
 lites, to the more or less complete obliteration of the walls of 
 the latter as recognisable structures. Lastly, sections taken 
 through the median plane of the frond, and parallel with its 
 
I3 8 TABULATE CORALS. 
 
 flat surfaces (PI. VII., fig. i e], show the visceral chambers of 
 the (here) thin-walled tubes to be crossed by remote and com- 
 plete tabulae, and to be connected by a well-developed system 
 of circular mural pores. 
 
 Formation and Locality. Not uncommon in the Wenlock 
 Limestone of Benthall Edge, Longhope, Dudley, and Stoke- 
 Edith. 
 
'39 
 
 CHAPTER V. 
 
 GENERA OF FAVOSITID^; (continued). 
 
 Genus MICHELINIA, De Koninck, 1842. 
 (An. foss. des terr. Garb, de le Belgique, p. 29.) 
 
 Gen. Char. Corallum forming hemispherical, depressed, or 
 pyriform masses, often of considerable size, composed of pris- 
 matic or subcylindrical corallites, in close contact throughout 
 their entire length. Walls not thickened to any unusual extent, 
 perforated by numerous mural pores, which are often multi- 
 serial, and have no definite arrangement. Calices polygonal or 
 subcylindrical, not surrounded by thickened margins. Tabulae 
 numerous, generally more or less curved with their convexities 
 upwards ; usually anastomosing with one another to a greater 
 or less extent, so as to give rise to a loose and open vesicular 
 tissue; and often carrying numerous vertically-directed spin- 
 ules. Septa represented by numerous radiately - arranged 
 longitudinal striae, ridges, or vertical rows of tubercles, varying 
 in number from twenty-five to forty. Under surface covered 
 by a concentrically-striated epitheca, which may or may not be 
 provided with hollow radiciform prolongations. 
 
 Obs. This well - known genus comprises a number of 
 Devonian and Carboniferous corals, which present a close 
 general resemblance to the larger forms of Favosites. The 
 corallum (fig. 21) is massive, usually more or less hemispheri- 
 
140 
 
 TABULATE CORALS. 
 
 Fig. 21. Michelinia convexa, D'Orb., viewed from above, 
 of the natural size, from the Corniferous Limestone of 
 Ontario. (After Billings.) 
 
 cal, or in the form of a flattened expansion, the under surface 
 of which is covered with a wrinkled epitheca. The corallum is 
 attached to some foreign body by the centre of its base, and 
 
 in some instances 
 the epitheca gives 
 off root - like pro- 
 longations in addi- 
 tion. In all the typi- 
 cal forms the coral- 
 lites are polygonal, 
 of larger size than 
 in the ordinary spe- 
 cies of Favosites, 
 and in close contact 
 throughout their en- 
 tire length; and they 
 radiate from the cen- 
 tre of the base, those 
 
 occupying the circumference of the mass being so highly in- 
 clined as to be nearly parallel with the epitheca, while those 
 in the middle are more or less nearly vertical. The visceral 
 chamber, like the corallite itself, is usually polygonal ; but in 
 some cases (e.g., M. cylindrica, E. and H.), the tube-cavity 
 is constricted at intervals by ring-like ridges, which give it 
 a cylindrical appearance. The walls, though moderately stout, 
 have none of the secondary thickening of the interior so 
 characteristic of Pachypora, Lindst, and its allies. The mu- 
 ral pores are numerous, circular, of variable size, and quite 
 irregular in their distribution. The chief noticeable feature 
 about the tabulae is their marked curvature, their convexities 
 being directed upwards. Moreover, the tabulae seldom extend 
 quite across the visceral tube, but in approaching the margin, 
 they usually unite with other smaller tabulae, so as to give rise 
 to the formation of numerous large-sized lenticular vesicles, 
 which are most abundantly developed near the sides of the 
 tubes. The extent, also, to which the tabulae thus become 
 
GENERA OF FAVOSITID^E. 141 
 
 vesicular varies in different species of the genus ; and the con- 
 dition of these structures is in any case very different to that 
 which obtains in Favosites (Emmonsid) hemispherica, Yand. and 
 Shum., where the tabulae are mostly actually " incomplete," and 
 do not become united with contiguous plates. The tabulae 
 often carry on their upper surface vertically-directed spinules, 
 which may be regarded as a continuation towards the centre of 
 the marginal septa. These latter are in the form of vertical 
 striae, or ridges, or rows of tubercles ; and their number varies 
 from twenty-five to fifty. 
 
 It will be evident from the above description that Michelinia 
 is a true Favositoid coral, very nearly allied to Favosites itself, 
 near which it has been almost uniformly placed by palaeontolo- 
 gists. It does not, in fact, differ fro pi Favosites proper in any 
 characters except that the tabulae usually subdivide and become 
 more or less united among themselves, while the septa are 
 more numerous, and are not spiniform, and the mural pores 
 are irregularly distributed. Of these peculiarities the subvesi- 
 cular character of the tabulae is the only one of generic import- 
 ance, and even this is not equally noticeable in all the species. 
 The occasional presence (as in M.favosa, Goldf.) of radiciform 
 prolongations from the lower surface apart from the fact of 
 the total absence of these structures in most of the species 
 cannot, in my opinion, be regarded as sufficient to overbalance 
 the many and weighty resemblances between this genus and 
 Favosites. I am therefore altogether unable to agree with my 
 friend Dr Lindstrom in thinking that Michelinia should be 
 removed from the FavositicUs and placed in the family of the 
 Cystiphyllidcz (On the Affinities of the Anthozoa Tabulata, 
 Ann. and Mag. Nat. Hist, ser. 4, vol. xviii. p. 12). 
 
 I shall in the meanwhile, for reasons to be stated imme- 
 diately, retain Pleurodictyum, Goldf., and C/wnostegites, E. 
 and H. ( = Haimeophyllum, Bill.), as generically distinct from 
 Michelinia, though I think that the first of these, at any rate, 
 will ultimately have to be united with the present genus. If 
 this course be followed, then the genus Michelinia is only 
 
1 42 TABULATE CORALS. 
 
 known with certainty from the Devonian and Carboniferous 
 rocks ; since the forms which have been noted as occurring in 
 the Upper Silurian deposits of North America appear to be 
 small discoid examples of the type of Pleurodictyum. My own 
 collection includes excellently-preserved specimens of M. con- 
 vexa, D'Orb., M. favosoidea, Bill., and M. (Emmonsid) cylin- 
 drica, E. and H. ; but as these are not only silicified, but have 
 their tubes entirely empty, they do not admit of being satisfac- 
 torily sectioned for the microscope. Through the kindness of 
 Mr Etheridge, I have also had the opportunity of examining 
 specimens of M. megastoma, Phill., M. tenuisepta, Phill., and 
 M. favosa, Goldf., from the Museum of Practical Geology. 
 As, however, I am not in the position of being able to give any 
 details as to the microscopic structure of any of the above, it 
 will be unnecessary to select any species for description. 
 
 Genus PLEURODICTYUM, Goldfuss, 1829. 
 (Petref. Germ., t. i. p. 113.) 
 
 Gen. Char. Corallum discoidal, with a slightly convex 
 upper surface, attached to foreign bodies by the centre of its 
 base, and having its lower surface covered by a well-developed, 
 concentrically-striated epitheca. Corallites diverging from the 
 centre of the base, those on the circumference being nearly 
 horizontal, while the median ones are more or less nearly per- 
 pendicular; their general shape polygonal or subcylindrical. 
 Walls of considerable thickness, pierced from side to side by 
 mural pores, which have no regular arrangement. Tabulae not 
 very numerous, nor markedly arched ; often inosculating to 
 some extent, but not giving rise to a vesicular or subvesicular 
 tissue. Septa rudimentary, in the form of marginal ridges or 
 rows of vertically-disposed spines. 
 
 Obs. This genus was founded for the reception of the 
 curious P. problematicum of the Devonian deposits, which is 
 still only known by means of casts of the tubes in sandstone. 
 
GENERA OF FA VOSITID^E. 143 
 
 The structure of these casts was well described by Edwards 
 and Haime (Pol. Foss. des Terr. Pal., p. 209), and the true 
 significance of the most singular of the features presented by 
 the genus was fully recognised by them. They placed the 
 genus, however, in the Perforate Zoantharia, in the immediate 
 neighbourhood of Protarcea and Litharcea, and thus failed to 
 appreciate its relationships with the Favositida. Dr Rominger 
 was, I believe, the first to point out (Amer. Journ. Sci. and 
 Arts, vol. xxxv. p. 82, 1863) that Pleurodictyum was really 
 founded upon casts of a coral allied to Favosites or Mickelinia ; 
 and he has recently united it with the latter genus (Foss. Corals 
 of Michigan, p. 72, 1876). At present, we are acquainted with 
 the actual corallum itself in more than one species of Pleuro- 
 dictyum ; and I shall defer any further remarks upon the genus 
 till I have described the only one of these which I have had 
 the opportunity of examining with proper fulness. 
 
 Pleurodictyum stylophorum, Eaton. 
 (Fig. 22, and PI. VIII., figs, i - i b.) 
 
 Astraa stylophora, Eaton (?), Geological Text-Book, 1832. 
 
 Pleurodictyum Americanum, Ferd. Roemer, Lethaea Palseozoica, PI. XXIII , 
 
 figs. 2 a and 2 b, 1876. 
 Michdinia trochiscus, Rominger, Fossil Corals of Michigan, p. 75, 1876. 
 
 Spec. Char. Corallum discoidal, with a slightly convex 
 upper surface, generally from an inch to an inch and a half in 
 diameter, and about half an inch or rather more in height ; 
 attached by the centre of the base to some foreign body such 
 as the stem of a Crinoid. Lower surface covered by a well- 
 developed epitheca, with strong concentric wrinkles, and also 
 with finer radiating strise. Corallites subpolygonal, very un- 
 equal in size, the larger ones from nearly two lines to about 
 three lines in diameter. Walls thick, perforated by irregularly- 
 placed mural pores. Septa in the form of from twenty-five to 
 thirty-five or more marginal ridges or vertical rows of blunt 
 spines. Tabulae few in number, slightly convex or horizontal, 
 
144 TABULATE CORALS. 
 
 sometimes uniting with one another, but not subvesicular in 
 character. The " vermiform body " of Pleurodictyum pro- 
 blematicum, Goldf., is sometimes (always ?) present in the 
 interior of the corallum. 
 
 Obs. This pretty little species seems to have been first 
 named Astrcea stylophora by Eaton, I presume in his ' Geolo- 
 gical Text- Book ' (published in 1832); though I am unable to 
 consult this work, and cannot speak positively upon this point. 
 Dr Rominger (loc. cit.\ in describing his Michelinia trochiscus, 
 gives the above as its synonym ; and assuming the correctness 
 of this, it would seem that Eaton's specific name has the clear 
 right to be retained, as no other species of Michelinia or Pleuro- 
 dictyum has been similarly entitled. Should it be found neces- 
 sary, for any reason, to abandon Eaton's name, then it would 
 be a question whether the present species should not stand as 
 Pleurodictyum Americanum, under which name it was well 
 figured and briefly described by Professor Ferd. Roemer in 
 1876 (Leth. Pal., PL XXIII., figs. 2 a, 2 6). Through the kind- 
 ness of my friend Mr George Jennings Hinde, I possess a few 
 specimens of this remarkable form, which is of special interest 
 as presenting us with the actual corallum of a form unques- 
 tionably congeneric with Pleurodictyum problematicum, Goldf, 
 though apparently specifically distinct. These I have sub- 
 mitted to a careful examination by means of thin sections, 
 and I shall now give the principal results of this, along with 
 some remarks upon the genus Pleurodictyum, and upon P. 
 problematicum, Goldf. 
 
 As before remarked, P. problematiciim is only known by 
 casts in sandstone, which are of not very rare occurrence in the 
 Devonian deposits of Europe and of Devonshire. Precisely 
 similar casts though probably specifically distinct occur in 
 the Onondaga sandstones of North America, and have been 
 well described and figured by Meek and Worthen, with a 
 somewhat doubtful reference of them to the European species 
 (Geol. of Illinois, vol. iii. p. 405, PI. IX., figs, i a-\ c, 1868). 
 In both these cases the fossil (fig. 22, A and B) consists of a 
 
GENERA OF FA VOSITID&. 145 
 
 series of prismatic or subcylindrical columns radiating from a 
 common base, in such a manner that those nearest the peri- 
 phery are horizontal or even reclined, and those in the centre 
 are vertical, while intermediate columns have correspondingly 
 intermediate grades of inclination. These columns are some- 
 times markedly striated with longitudinal ridges, as well as 
 marked with small rounded elevations (fig. 22, B) ; while each is 
 
 Fig. 22. A, Lower surface of the cast of Pleurodictyum problematicum, Goldf., from the Lower 
 Devonian of Germany, of the natural size (after Roemer), showing the vermiform body in 
 the centre ; B, A few of the separate casts of the tubes of Pleurodictyum problematicum, 
 Goldf. , from the Devonian of the Eifel, showing the casts of the mural pores and inter- 
 septal grooves, enlarged (after Milne-Edwards and Haime) ; c, Upper surface of the coral- 
 lum of Pleurodictyum stylophorum, Eaton, from the Hamilton group of North America, of 
 the natural size, showing the form of the calices (original) ; D, Lower surface of another 
 example of the same, of the natural size, showing the striated epitheca, and the point 
 where the corallum was attached to the stem of a Crinoid (original). 
 
 connected with its neighbours by a number ot cylindrical rods. 
 The above appearances are now readily intelligible, as, indeed, 
 they were to all intents and purposes even to the authors of the 
 ' Polypiers fossiles,' though these distinguished observers had 
 never seen any actual coral capable of giving rise to a similar 
 cast. The prismatic columns of P. problematicum are, then, 
 casts of the polygonal corallites of a Favositoid corallum, of a 
 
 K 
 
i 4 6 TABULATE CORALS. 
 
 discoidal form ; the rounded tubercles which they carry upon 
 their surface, as well as the rods which connect contiguous 
 columns, are casts of the 'mural pores, left by the solution of the 
 thick walls ; and the vertical ridges (not always present) are 
 casts of the grooves between the septal ridges or striae. More- 
 over, perfect examples of P. problematicum show that the cor- 
 allum was concavo-convex, its under surface being concave 
 (probably a character of specific value), and covered by a con- 
 centrically-striated epithecal membrane. So far there is no 
 difficulty in interpreting the peculiarities of the P. problemati- 
 cum of the European Devonian by the light afforded by the 
 well-preserved coralla of allied forms in the corresponding forma- 
 tion in North America ; but there remain two points of difficult 
 interpretation. One of these points consists in the occasional 
 existence of numerous small pits much more numerous than 
 the corallites themselves on the upper surface of the cast of 
 the epitheca (see Pol. Foss. des Terr. Pal., PI. XVIII., figs. 4 
 and 4 a). Messrs Meek and Worthen have not only noticed 
 the same phenomenon in the American specimens, which they 
 provisionally refer to P. problematicum, Goldf. ; but they notice, 
 in addition, that the corallites which rest directly upon the 
 epitheca are connected with the latter by rods precisely similar 
 to those which unite the different corallites with one another. 
 They suggest that this indicates the occurrence of "pores" 
 passing through the base ; but it may be offered as a probable 
 explanation that these really indicate the existence in this 
 particular species of numerous radiciform and hollow pro- 
 longations of the lower surface of the epitheca, such as 
 are known to occur in Michelinia favosa, Goldf, and which, 
 after all, are essentially of the same nature as the "mural 
 pores." 
 
 The other point of difficulty consists in the presence in many 
 (but apparently not in all) specimens of P. problematicum, 
 Goldf., of the curious structure known as the " vermiform 
 body." This body (fig. 22, A) has the form of a cylindrical, 
 crooked, often S-shaped rod, occupying the centre of the base 
 
GENERA OF FAVOSITID^E. 147 
 
 of the corallum, and having the corallites radiating from it on 
 all sides. None of the American examples referred to this 
 species by Meek and Worthen (loc\ cit.) show any traces of 
 this structure. The nature of this curious body has been much 
 disputed, but it has generally been regarded as being one of 
 two things viz., either the cast of the burrow of some boring 
 Annelide which mined the coral after the latter had attained 
 its full growth, or else the calcareous tube of some Annelidous 
 genus like the existing Serpula, to which the coral attached 
 itself when young, and which it subsequently enveloped in the 
 process of development. This latter view, which would make 
 the phenomenon an instance of " commensalism," is the one 
 which was adopted by Edwards and Haime, and in which they 
 have been followed by most subsequent writers. It is a note- 
 worthy fact, however, that a tube of precisely the same nature 
 has been found by me to exist in the only specimens of P. sty- 
 lophorum, Eaton, which I have been able to section for the 
 microscope ; and though I do not pretend to offer any satis- 
 factory explanation as to its true significance, I have been able 
 to satisfy myself of the following points, which have a consider- 
 able bearing upon any view which may be framed upon this 
 subject : 
 
 1 . The mere fact of the occurrence of this peculiar structure 
 in two different species of the same genus, in regions as widely 
 remote as Europe and North America, is primd facie, though 
 by no means conclusive, evidence against the view that the 
 " vermiform body " is merely the work of a parasite, or is the 
 tube of an Annelide upon which the corallum grew. 
 
 2. The " vermiform body " in P. stylophorum, Eaton, either 
 existed before the coral, or grew simultaneously with it. This 
 is shown incontrovertibly by the fact that, in sections, the coral- 
 lites are seen to accommodate their shape to that of the tube, and 
 to be fixed to it in places by their bases. In no instance ob- 
 served by me does the tube cut across the corallites (see 
 PI. VIII., figs, i - i b, where the tube is shown in section). 
 This observation is sufficient to conclusively negative the view 
 
148 TABULATE CORALS. 
 
 that the tube can be the work of some parasitic animal which 
 bored into the coral after the latter was formed. 
 
 3. The tube was by no means confined to the mere base of 
 the coral, nor did it lie like the letter S in a single plane. On 
 the contrary, it traversed the corallum in a loose and open 
 spiral, so that both vertical and horizontal sections cut it at 
 various points (see PL VIII., figs, i-i b). 
 
 4. The tube (in adult specimens, at any rate) was completely 
 concealed within the corallum, and was, to all appearance, alto- 
 gether superior to the epitheca. Whether or not it had any 
 opening upon the upper surface of the corallum, I cannot say. 1 
 
 5. The walls .of the tube are extremely thin, calcareous, and 
 apparently destitute of any definite structure. The interior is 
 usually filled with transparent calcite, but occasionally there are 
 seen inside it numerous spheroidal or ovoid opaque bodies, as 
 to the nature of which I can offer no opinion whatever (PI. 
 VIII., fig. i a). It will be seen from the above that this 
 peculiar structure is one well worthy of further examination 
 by those who may have calcareous specimens suitable for the 
 preparation of microscopic sections. My own observations are 
 much too limited to enable me to come to any definite conclu- 
 sions as to its true nature ; but they are at the same time suffi- 
 cient to make me dubious as to the received explanations upon 
 this subject. 
 
 Returning now to P. stylophorum, Eaton, I may give a brief 
 account of its structure, as shown by microscopic sections, it 
 being the only species of Pleurodictyum which, to my know- 
 ledge, has ever been examined by this method. The general 
 form of the corallum, as seen in fig. 22, c and D, is that of a 
 small discoid expansion, the upper surface of which carries the 
 calices, and is more or less convex ; while the lower surface is 
 generally flat or slightly convex, and is covered by a strong 
 
 1 Dr Rominger (Amer. Journ. Sci. and Arts, vol. xxxv. p. 82), however, states 
 that he has observed specimens in which the vermiform tube opens upon the upper 
 surface of the corallum by a round mouth. His further statement that the tube 
 traverses the substance of the corallum irrespective of the direction of the corallites 
 through which it seems to cut, is not borne out by my specimens. 
 
GENERA OF FA VOSITID^E. 
 
 149 
 
 epitheca, marked with concentric and radiating striae. All my 
 specimens show a distinct cicatrix of attachment, the foreign 
 body upon which the coral grew being in one instance unques- 
 tionably the column of a Crinoid (fig. 22, D). I can also detect 
 no traces of perforations nor of radiciform prolongations of the 
 epitheca. The upper surface (fig. 22, c) shows the apertures 
 of the polygonal, irregularly-sized corallites. Tangential sec- 
 tions, taken just below the upper surface (PI. VIII., fig. i a), 
 cut across the corallites at right angles, and show that the 
 polygonal tubes are surrounded by thick walls, those of con- 
 tiguous corallites remaining so far distinct as to be always 
 separated from one another by a marked and definite line of 
 demarcation. The same feature is shown by sections which 
 cut the corallites longitudinally (PI. VIII., figs, i and i b}. 
 Both these kinds of sec- 
 tions exhibit, further, the 
 well -developed but irreg- 
 ularly-distributed " mural 
 pores," together with cer- 
 tain other openings of a 
 seemingly different nature, 
 the structure of which I 
 shall endeavour to eluci- 
 date by the help of the an- 
 nexed diagram. Remem- 
 bering that the mural pores 
 are apertures which pass 
 through the walls of the 
 corallites from side to side, 
 it is easy to see how and 
 under what forms they may 
 present themselves in thin 
 sections of the corallum of 
 any of the Favositida. In 
 
 transverse sections (fig. 23, A and c) the pores are usually 
 not to be detected, or only here and there, and they present 
 
 Fig. 23. Semi-diagrammatic representations of 
 sections of the corallum of Favosites and Pleura- 
 dictyum, showing "mural pores" and "intra- 
 mural canals," the former shaded black, the 
 latter left unshaded. A and B, Transverse and 
 vertical sections of Favosites, showing mural 
 pores only; c and D, Transverse and vertical 
 sections of Pleurodictyum, showing mural pores 
 and intramural canals. 
 
1 5 o TABULATE CORALS. 
 
 themselves as canals which run right across the walls of 
 two contiguous corallites, and place their visceral chambers 
 in direct communication. In vertical sections (fig. 23, B and D), 
 on the other hand, the mural pores may present themselves 
 under one or other of two forms, or under both of these. 
 Thus they may appear either as canals running directly across 
 the wall between two contiguous tubes, or (if the section hap- 
 pen to coincide more or less nearly with the plane of one of 
 the walls) as scattered circular pores situated within the space 
 bounded by the lateral walls of the corallites. All the Favosi- 
 tidcz may show the phenomena just described ; but in Pleuro- 
 dictyum and some other types thin sections show the existence 
 of another set of canals, which appear to run entirely within the 
 substance of the walls, and to have a course parallel with the 
 flat surfaces of the latter. The canals in question are best 
 seen in transverse sections (fig. 23, c), where they are shown 
 as distinctly circumscribed circular openings, placed at the 
 point of union of the walls of two contiguous corallites, or 
 situated within the actual substance of the wall. Similar open- 
 ings are seen in long sections (fig. 23, D), but the evidence is 
 here not so satisfactory as in the preceding case, since we 
 might be dealing with mural pores passing through the angles 
 of the prismatic corallites. What these canals are, it is difficult 
 to say, but they are certainly distinct from the " mural pores ; " 
 and as it is convenient to have a distinct name for them, I shall 
 call them the " intramural canals." Possibly they may only 
 be due to imperfect calcification or coalescence of the walls of 
 the corallites ; but that they are distinct from the mural pores 
 is shown by the fact of their occurrence in forms like Lyopora, 
 Nich. and Eth. jun., in which these latter openings are not 
 known to occur. In Pleurodictyum the " intramural canals," 
 as just defined, are neither numerous nor very conspicuous. 
 They are, however, present in a marked form in Columnopora, 
 Nich., and in Lyopora, Nich. and Eth. jun., in both of which 
 they appear to have been regarded as " coenenchymal tubules ; " 
 though their sparse and scattered arrangement, and their total 
 
GENERA OF FAVOSITID&. 15 1 
 
 absence in parts of the corallum, together with the fact that 
 they traverse the walls in different directions, would entirely 
 negative this view. 
 
 The only remaining points in the anatomy of Pleurodictyum 
 stylophorum which need notice, concern the condition of the 
 septa and tabulae. Returning again to transverse or tangential 
 sections of this species (PL VIII., fig. i a), we find the septa 
 represented by short spines arranged in vertical rows, quite 
 resembling the same structures in various species of Favosites. 
 The tabulae are seen in long sections (PI. VIII., figs, i and i b} 
 to be always well developed, and to have the form of strong 
 horizontal flexuous plates, which are not strongly convex, and 
 which do not give rise to anything that could be appropriately 
 called " vesicular tissue," though they not uncommonly unite 
 with one another to a limited extent. Owing to the shortness 
 of the corallites, there are usually not more than four or five 
 tabulae in a single tube. 
 
 Upon the whole, it will be seen by the preceding description 
 that there is a close relationship between Pleurodictyum, Goldf., 
 and Michelinia, De Kon., and it is a matter of question if the 
 two genera can be kept apart. Should it be found necessary to 
 merge these two genera, it is Michelinia which will have to 
 give way to the older Pleurodictyum, and not, as some writers 
 assume, the latter to the former. In the meanwhile, however, 
 I think it safest to keep the two distinct until, at any rate, the 
 structure of Pleurodictyum has been fully worked out. If this 
 course be followed, Pleurodictyum, Goldf., will contain corals 
 in most respects quite similar to Mickelinia, De Kon., but dis- 
 tinguished by their small size and discoid form, and by the fact 
 that the tabulae are not markedly convex, and do not subdivide 
 or inosculate to any notable degree. It is possible (though not 
 likely) that the " intramural canals " which I have described 
 as occurring in Pleurodictyum may be found to distinguish the 
 genus further from Michelinia. I need only add that it is 
 certain that Dr Ferd. Roemer must have been misled by 
 appearances when he asserts (Leth. Pal., Explanation of PI. 
 
i 5 2 TABULATE CORALS. 
 
 XXIII., 1876) that there are no tabulae in Pleurodictyiim, these 
 structures being quite as well developed as could be expected 
 in such short tubes. 
 
 Formation and Locality. Hamilton group (Devonian), 
 Hamburg, State of New York, Coll. George J. Hinde. (Judg- 
 ing from the figures, it would seem not improbable that the 
 coral described by Prof. Ferd. Roemer in the ' Silurian Fauna 
 of West Tennessee/ p. 19, 1860, under the name of Calamopora 
 Forbesi, var. discoidea, may be really a species of Pleurodictyum 
 allied to P. stylophorum, Eaton. It is probable, also, that the 
 nummiform species of Michelinia alluded to by Dr Rominger 
 in the ' Foss. Corals of Michigan/ p. 72, as occurring in the 
 Upper Silurian strata of North America, are referable to 
 Pleurodictyum, if the latter genus is to be kept distinct.) 
 
 Genus CHONOSTEGITES, Edwards and Haime, 1851. 
 
 (Pol. Foss. des Terr. Pal., p. 299.) 
 Haimeophyllum, Billings, Canad. Journ., new sen, vol. iv. p. 139, 1859. 
 
 Gen. Char. Corallum forming large subhemispherical, sub- 
 fasciculate masses, composed of cylindrical corallites, which grow 
 side by side, and are annulated by numerous close-set, hollow, 
 periodic expansions, which alternate with as many circular con- 
 strictions. For the most part the corallites are separate, except 
 that they are united by the periodic expansions above spoken 
 of, which thus form a succession of concentric floors, connecting 
 the tubes with one another. In the parts between these periodic 
 floors the corallites are enclosed each by a distinct epitheca, and 
 the walls are imperforate. There are, however, often parts of 
 the corallum in which the walls of contiguous corallites are in 
 close contact, and then numerous " mural pores " are developed. 
 Tabulae numerous, arched, often uniting with one another in 
 such a way as to give rise to a loose and open subvesicular 
 tissue, which is continued into the hollow periodic expansions 
 of the corallites. Septa in the form of short spines in the in- 
 
GENERA OF FA VOSITIDJ5.. 153 
 
 terior of the tubes. New corallites produced by gemmation 
 from the hollow periodic expansions in the intervals between 
 the old cups. 
 
 Obs. It is perhaps impossible for any one who has not 
 access to the original examples of Chonostegites Clappi, E. and 
 H., and Michelinia intermittens, Bill, to entirely and finally 
 unravel the confusion in which the present genus is enveloped. 
 I shall, however, briefly state the conclusions at which I have 
 arrived upon this subject, and some of which I regard as quite 
 certain. 
 
 The genus Chonostegites was founded by Milne-Edwards and 
 Haime for the reception of a coral unquestionably possessing 
 the general characters given in the above generic diagnosis, 
 which is based upon specimens of the coral described by Billings 
 under the name of Haimeophyllum inordinatum. They state 
 that their specimens are of Devonian age, and that they were 
 found in the drift of Dayton in Ohio. Under these circum- 
 stances it cannot be doubted but that the original specimens of 
 Chonostegites Clappi, E. and H., were derived from the Corni- 
 ferous Limestone, the silicified corals of this formation being 
 abundantly distributed in the drift of various parts of the 
 Northern United States. 
 
 At a later date, in 1859, Mr Billings described two corals 
 from the Corniferous Limestone of Canada, under the names of 
 Michelinia intermittens and Haimeophyllum inordinatum, the 
 latter being made the type of a new genus. With regard to 
 Michelinia intermittens, Mr Billings himself expresses a doubt 
 if it be truly separable from Chonostegites Clappi, E. and H., 
 adding that in this case the species should stand as Michelinia 
 Clappi. This opinion on the part of Mr Billings was based 
 upon the observation that in those portions of the corallum of 
 M. intermittens in which the corallites are in contact they are 
 prismatic in shape, and that they possess mural pores. On the 
 other hand, Haimeophyllum is founded for a coral which is said 
 to differ from Michelinia only in the fact that the corallites are 
 not in close contact, are subparallel, and are united by the coal- 
 
154 TABULATE CORALS. 
 
 escence of periodic expansions of the margins of the calices, 
 while mural pores are alleged to be absent. 
 
 At a still later date, in 1876, Dr Rominger (Foss. Cor. of 
 Michigan) placed Chonostegites Clappi, E. and H., \n. Michelinia, 
 and referred Michelinia intermittens, Bill., in part to the same 
 species ; while he considered M. intermittens as also in part 
 synonymous with M. (Emmonsia) cylindrica, E. and H. 
 
 Having carefully examined an excellently-preserved series of 
 specimens of Haimeophyllum inordinatum, Bill., I have failed 
 to discover any character by which it could be specifically 
 separated from Chonostegites Clappi, E. and H. Mr Billings 
 was undoubtedly in error in supposing that " mural pores " are 
 absent in Haimeophyllum, these openings being present in all 
 parts of the corallum where the tubes come into actual contact. 
 I regard Haimeophyllum, Bill., therefore, as a synonym of 
 Chonostegites, E. and H., and shall discuss the relations of the 
 latter to Michelinia, De Kon., later on. 
 
 In the second place, I think Michelinia intermittens, Bill., to 
 be merely a variety of Haimeophyllum ordinatum, Bill., with 
 the tubes more extensively in contact than is usual in this 
 variable species. As the latter species is in my opinion the 
 same as Chonostegites Clappi, E. and H., it follows that M. in- 
 termittens, Bill., is a synonym of C. Clappi, as it is in part made 
 to be by Dr Rominger. I need only add that there cannot be 
 the slightest hesitation in rejecting Dr Rominger's further view 
 thatJ^f. intermittens, Bill., is in part identical vi\\h.M. cylindrica, 
 E. and H., since Billings expressly states that his species was 
 founded upon a single specimen ; and it cannot, therefore, pos- 
 sibly be partly referable to one species and partly to another. 
 
 Before discussing the relations between Chonostegites and 
 Michelinia, and the possible propriety of uniting them with one 
 another, it will be well to briefly describe the structure of C. 
 Clappi, the type and the only satisfactorily differentiated species 
 of the former genus. 
 
GENERA OF FAVOSITID^E. 155 
 
 Chonostegites Clappi, Edwards and Haime. 
 (PL VIII., figs. 2-2 c.) 
 
 Chonostegites Clappi, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 
 p. 299, 1851. 
 
 Michelinia intermittens, Billings, Canad. Journ., new ser., vol. iv. p. 113, 1859. 
 Haimeophyllum inordinatum, Billings, Canad. Journ., new ser., vol. iv. p. 
 
 139, fig. 29, 1859. 
 Michelinia Clappi, Rominger, Foss. Cor. of Michigan, p. 75, PL XXVIIL, 
 
 figs. 3 and 4, 1876. 
 
 Spec. Char. Corallum often of considerable size, composed 
 of subparallel, essentially circular, tubular corallites, which are 
 for the most part free, though sometimes partially in contact, 
 in which latter case they become more or less polygonal by 
 mutual pressure. In parts where they are in contact the walls 
 of the corallites are perforated by numerous irregularly-distri- 
 buted mural pores, which place the visceral chambers of con- 
 tiguous tubes in direct communication. When they are not in 
 contact, the corallites are individually enclosed in a distinct 
 epitheca, which is not perforated, and which is marked with 
 numerous fine encircling strise. Where not in contact, also, 
 the corallites are annulated by numerous alternate constrictions 
 and dilatations, giving to each the appearance of a succession 
 of funnels vertically superimposed upon one another. The 
 dilatations of contiguous tubes are placed more or less at the 
 same levels, and unite with one another, so as to form a succes- 
 sion of concentrically superposed floors, which can be shown to 
 be hollow, and thus to place the visceral chambers of neigh- 
 bouring tubes in actual communication. Viewed from above, 
 the calices are seen to be circular, and to be surrounded at a 
 little distance by faintly-marked polygons inscribed on the 
 upper surface of the connecting-floors. Tabulae numerous, 
 arched, inosculating to a greater or less extent, and forming 
 large lenticular cells, which are continued into the hollow hori- 
 zontal connecting-floors. Septa in the form of short spines 
 arranged in vertical rows. The upper surfaces of the tabulae 
 
156 TABULATE CORALS. 
 
 are also often serrated with erect spinules, which appear to 
 represent continuations of the septa towards the axis of the 
 visceral chamber. New corallites budded forth between the 
 old calices from the hollow connecting-floors. 
 
 The dimensions of the corallites, the degree to which they 
 are in contact, and the closeness of the periodical expansions, 
 vary in different examples. In the most typical forms, the 
 tubes themselves are about two lines in diameter, but the 
 diameters of the polygons inscribed round these upon the upper 
 surfaces of the horizontal floors (where recognisable) are three 
 lines or more. In other examples the tubes themselves may 
 reach three lines or over in diameter. The periodical expan- 
 sions which give rise to the horizontal floors by their union are 
 mostly from one line to a line and a half distant from one 
 another, but they may be two or even three lines apart. The 
 corallites are often only from half a line to a line apart in their 
 constricted portions, but they may be distant two, three, four, 
 or even five lines, and, on the other hand, they generally ap- 
 proach one another in parts of a large colony, so as to become 
 closely contiguous or coalescent. 
 
 Obs. It is not necessary to add anything to the above de- 
 scription of the general characters of this singular species (PI. 
 VIII., figs. 2-2c). I may, however, shortly describe the ap- 
 pearances presented by thin sections, by which alone the internal 
 anatomy can be satisfactorily studied. The most instructive 
 sections are vertical ones (PI. VIII., fig. 2 c), which admirably 
 exhibit the alternately and rapidly constricted and dilated tubes 
 of the corallites, each of which looks like a series of wide and 
 shallow funnels arranged in vertical order. These sections also 
 show the important fact that the periodic expansions of the 
 tubes are really hollow prolongations of the visceral cavities of 
 the corallites, so that by the union of these to form the hori- 
 zontal connecting-floors all the polypes of the colony are placed 
 in actual organic connection. The tubes are traversed by well- 
 developed, arched, flexuous, or nearly horizontal tabulae, the 
 upper surfaces of which commonly carry short erect spines, 
 
GENERA OF FAVOSITID^E. 157 
 
 and which more or less extensively anastomose with one an- 
 other, precisely as in the genus Michelinia, De Kon. The 
 tabulae are continued into the hollow horizontal expansions of 
 the tubes, where they continue to present the same characters 
 of irregular anastomosis as in the cavities of the corallites 
 themselves. Transverse sections (PI. VIII., fig. 2 b) exhibit 
 the corallites themselves, cut across at right angles to their 
 long axis, together with irregular moieties of the hollow con- 
 necting-floors, which come into view in consequence of their 
 not lying in a single horizontal plane. The only special fea- 
 tures exhibited by sections of this nature are that the corallites 
 are provided with distinct and separate walls, and that the 
 septa are represented by radially-disposed spinules. 
 
 From the preceding description it will be clear that we have 
 to deal in Chonostegites Clappi, E. and H., with a coral in many 
 respects closely allied to Michelinia. If we take typical ex- 
 amples of this species, in which the corallites stand wide apart, 
 each enclosed in its own epitheca, and united with its fellows 
 by hollow horizontal expansions derived from the visceral cham- 
 ber, then, it is true, we should feel no hesitation in separating 
 Chonostegites from Michelinia as a distinct genus. Even in such 
 examples, however, the hollow periodic expansions of the tubes 
 may be properly regarded as homologous with the "mural pores" 
 of Michelinia. If, on the other hand, we examine a portion of 
 the colony of Chonostegites Clappi, in which the corallites are in 
 actual contact and have their walls perforated by numerous 
 mural pores, then we feel at a loss to produce a single charac- 
 ter by which the species could be generically separated from 
 Michelinia. Moreover, the curious M. (Emmonsia) cylindrica 
 of Edwards and Haime is a distinct connecting-link between 
 the present species and the typical forms of Michelinia, since it 
 exhibits slight periodic constrictions of its tubes, and the mural 
 pores are generally confined to the dilated portions of the 
 corallites. 
 
 Upon the whole, however, I prefer keeping Chonostegites dis- 
 tinct from Michelinia, in the meanwhile at any rate. It maybe 
 
158 TABULATE CORALS. 
 
 added that the reference of the genus by Milne-Edwards and 
 Haime to the Halysitida t in the vicinity of Syringopora, is based 
 upon a solid foundation of structural likeness, since the connect- 
 ing-floors of Chonostegites are the homologues of the hollow 
 connecting-tubes in Syringopora, and the genus thus forms a 
 true link between Michelinia and Syringopora. 
 
 Formation and Locality. Not uncommon in the Corniferous 
 Limestone of Walpole, Ontario. 
 
159 
 
 CHAPTER VI. 
 
 GENERA OF FAVOSiTiD/E (continued). 
 
 Genus COLUMNOPORA, Nicholson, 1874. 
 
 (Geol. Mag., new sen, vol. i. p. 253, fig. i.) 
 Houghtonia, Rominger, Foss. Cor. of Michigan, p. 17, 1876. 
 
 Gen. Char. Corallum massive, forming subhemispherical or 
 pyriform masses, often of considerable size, composed of sub- 
 polygonal or subcircular corallites, which radiate from the base, 
 and are for the most part in contact and firmly united by their 
 walls. Septa in the form of marginal ridges, generally about 
 twenty in each corallite. Walls thick, perforated by numerous 
 large, close-set, oval mural pores, arranged in rows between the 
 septal ridges. Tabulae numerous, generally more or less flexu- 
 ous, often uniting with one another, complete. No columella 
 and no true ccenenchyma. 
 
 Obs. The corallum in this genus is massive, and in general 
 aspect very similar to that of any of the larger species of 
 Favosites y though distinguished from the latter even by a very 
 cursory examination. The corallites are in reality subpolygonal, 
 but the angles of the tubes are more or less rounded off", 
 and they thus become subcircular in form (PI. VII., fig. 2). 
 The real structure of the corallum can be best investigated by 
 means of transparent sections, though many of its most import- 
 ant features can be studied in the actual specimens. The coral- 
 
160 TABULATE CORALS. 
 
 lites are essentially in contact with one another if not invari- 
 ably, certainly as a general rule throughout their entire length; 
 though occasionally limited tubular spaces are left at the point 
 of junction of three or four of the corallites. 1 Moreover, thin 
 transverse sections (PI. VII., fig. 2 a) prove incontrovertibly 
 that the walls of the corallites are firmly amalgamated with one 
 another, the junction between contiguous tubes being marked 
 by a wavy dark line. Occasionally, as just remarked, the sec- 
 tions show a tubular space at the angles of junction of the 
 corallites, and these spaces are definitely circular or oval, and 
 are accompanied by smaller rounded and definite vacuities (PI. 
 VII., fig. 2 b) y which are situated in the substance of the walls 
 themselves. These spaces I regard as being cross-sections of 
 tubes which pass through the thick walls longitudinally, and as 
 being, therefore, of the same nature as the canals which I have 
 described in Pleurodictyum under the name of " intramural 
 canals." Similar tubes occur in the walls of Lyopora, Nich. 
 and Eth. jun. ; and though I am uncertain as to their true 
 nature, they are clearly endothecal, and cannot be of the nature 
 of " ccenenchymal tubes." They are, further, very minute, and 
 only the largest of them would be recognised by the use of a 
 hand-lens upon actual specimens. Vertical sections (PI. VII., 
 fig. 2 c] entirely confirm the evidence derivable from transverse 
 slices as to the absence of anything which could properly be 
 called coenenchymal. The walls, as before, are firmly united, 
 and the boundary between contiguous tubes is marked by a 
 sinuous dark line, occasionally interrupted by an irregular or 
 oval space. The septa are best studied in transverse sections 
 (PL VII., figs. 2 a and 2 b), though excellently seen in the actual 
 
 1 Occasional and partial absence of complete contact between the tubes is by no 
 means an unusual phenomenon in genera in which the corallites are normally and 
 regularly polygonal and accurately contiguous. Thus, in Columnaria (Favistelld) 
 alveolata, Goldf., it is not uncommon for the tubes close to their mouths to become, 
 in parts of the corallum, slightly separate, in which case they are also subcircular, 
 though the corallites are ordinarily prismatic and in close contact. In Columnaria 
 (Favistella) calicina, Nich., again, some of the corallites are always more or less 
 disjunct and subcircular, while others are always polygonal and firmly united by 
 their walls. 
 
GENERA OF FAVOSITID^E. j6i 
 
 specimens themselves. They have the form of from fifteen to 
 twenty or more longitudinal ridges, which have broad bases, 
 and extend only a very limited distance inwards towards the 
 centre of the visceral chamber. The tabulae are seen in verti- 
 cal sections (PI. VII., fig. 2 c] to be complete and numerous, 
 more or less flexuous, and often uniting to a limited extent with 
 one another. They do not, however, carry this process of 
 anastomosis so far as to give rise to anything like the " sub- 
 vesicular " tabular tissue of Mickelinia. Lastly, the mural pores 
 are seen both in transverse and longitudinal sections, though 
 best in the latter. In transverse sections (PI. VII., fig. 2 a) 
 they appear as transverse channels crossing the walls, and allow- 
 ing contiguous tube-cavities to communicate. In vertical sec- 
 tions they are only seen where the plane of the section may 
 happen to coincide with that of one of the walls of the tubes, 
 and then they are seen to have the form and arrangement ob- 
 servable by the ordinary methods of examination in the actual 
 specimens. They appear, namely (PI. VII., figs. 2 c and 2 d), 
 in the form of numerous longitudinally-placed oval pores of 
 large size, which occupy the interseptal spaces, and place the 
 visceral cavities in direct and free communication. The num- 
 ber of these pores in a given space is not absolutely uniform 
 in all parts of a given specimen ; but they are usually placed 
 at much less than their own diameter apart, measured both 
 vertically and laterally, so that the walls become completely 
 cribriform. 
 
 In his excellent work upon the Fossil Corals of Michigan, Dr 
 Rominger, in 1876, founded the new genus Houghtonia, to in- 
 clude certain corals from the Cincinnati group of North Amer- 
 ica, which I cannot doubt to be really congeneric with the 
 previously described Columnopora. Indeed, Dr Rominger has 
 himself admitted this identity in a note appended to a later 
 edition of the same work (1877). In his description of the 
 genus Houghtonia> as originally published, and in the note just 
 alluded to, in which he admits that this name must be abandoned 
 in favour of Columnopora, Dr Rominger states that the coral- 
 
 L 
 
1 62 TABULATE CORALS. 
 
 lites are often separated from one another by an irregular 
 cellular coenenchyma, and that the walls of the tubes when 
 contiguous are not perforated by mural pores, though he gives 
 no drawings of the structure of the corallum which would sup- 
 port either of these statements. I cannot, of course, offer any 
 opinion as to the phenomena presented by Dr Rominger's speci- 
 mens, as I have not had any opportunity of examining them, 
 and I should not wish to dogmatise as to examples which have 
 not come under my direct observation. It must be borne in 
 mind, however, that the specimens in my possession are the 
 ones upon which the genus was founded, and that they are there- 
 fore the types of the genus. These specimens have been sub- 
 jected to a careful macroscopic and microscopic examination, 
 and I can confidently affirm that they possess walls of an exag- 
 geratedly perforate type (as compared with Favosites) ; that 
 their corallites are for the most part indubitably in contact, with 
 their walls absolutely fused with one another; and that any 
 interspaces which may here and there exist between the coral- 
 lites admit of being explained upon a different supposition than 
 that they are of the nature of " ccenenchymal tubes." The 
 drawings which I have given, being taken by the camera lucida 
 from microscopic slides, will sufficiently prove the accuracy of 
 these statements. 
 
 A more difficult point to settle concerns the relations of 
 Columnopora to Calapcecia, Billings ; and as I have no speci- 
 mens of the latter, I shall here say the little that is necessary 
 concerning the curious types included by the eminent Canadian 
 palaeontologist under the above name : 
 
 The genus Calapcecia was defined by Mr Billings in the 
 'Canadian Naturalist' (2d sen, vol. ii. p. 425, 1857) as 
 follows : 
 
 " Corallum composite, forming hemispherical or subspherical 
 colonies. Corallites slender, tubular, perforated as in Favosites, 
 and with their outside striated by imperfectly-developed costae. 
 Radiating septa (in the species at present known) about twenty- 
 four. Tabulae thin, and apparently in some instances not com- 
 
GENERA OF FAVOSITID^E. 163 
 
 plete. When the corallites are not in contact, the space be- 
 tween them is filled with a variously-formed vesicular tissue. 
 This genus resembles Heliolites, but differs therefrom in having 
 double the number of septa and the walls perforated." 
 
 Two species were described by Mr Billings as belonging to 
 this genus viz., C. Canadensis, from the Black River Lime- 
 stone, and C. Huronensis, from the Hudson River formation. 
 The former is stated to have corallites about one line in dia- 
 meter, and generally in contact, although still remaining cir- 
 cular ; while the mural pores are arranged in horizontal rows 
 running all round the tube, one row between each pair of tabulae. 
 The latter was separated specifically from C. Canadensis, prin- 
 cipally upon the ground of the greater slenderness of its tubes. 
 Neither of these forms was figured. From the above descrip- 
 tion it would appear that Calapcecia Canadensis and C. Huron- 
 ensis are corals nearly allied to the form which I have de- 
 scribed as Columnopora cribriformis ; but such a conclusion has 
 been rendered very hazardous by the publication by Mr Bil- 
 lings, at a later date, of a third species of Calapcecia, which was 
 both described and figured (Cat. Sil. Foss. of Anticosti, p. 32, 
 fig. 15, 1866). The species in question (viz., C. Anticostiensis] 
 is stated to have a hemispheric corallum, the corallites some- 
 times in contact, but usually distant from one another by a 
 quarter or half a line. The shape of the corallites is circular, 
 and they are surrounded on the exterior by a fringe of well- 
 developed costce, while the spaces between them are subdivided 
 by horizontal and close-set exothecal plates. The septa have 
 the form of longitudinal striae, and tabulae were only obscurely 
 seen. In a note Mr Billings adds that this species would seem 
 to be congeneric with Syringophyllum organum. 
 
 Whether or not Mr Billings be correct in the suggestion just 
 alluded to, the above description and the figures which accom- 
 pany it leave no doubt whatever as to the entire distinctness 
 of Calapcecia Anticostiensis, Bill., and Cohtmnopora cribriformis, 
 Nich. If, therefore, the originally-described species viz., Cala- 
 pcecia Canadensis and C. Huronensis are to be regarded as 
 
164 TABULATE CORALS. 
 
 congeneric with C. Anticostiensis, then it is clear that the genus 
 Columnopora has no relationships with Calapcecia. This, at 
 any rate, seems to be the only conclusion that can safely be 
 arrived at, until the original specimens of Calapcecia shall have 
 been more fully examined and described. 
 
 The geological range of Colnmnopora, so far as known, is a 
 very limited one, the type-species being confined to the Lower 
 Silurian (Cincinnati group) of North America. The type of 
 the genus is C. cribriformis, Nich., of which I append the fol- 
 lowing brief description. Judging from the figures given, I 
 should imagine C. (Houghtonia) Huronica, Rom., to be at 
 most a variety of C. cribriformis; but as the corallites are 
 apparently to a considerable extent disjunct, it may prove to 
 be a separate species when it shall have been examined by 
 means of thin sections. 
 
 Columnopora cribriformis, Nicholson. 
 (PI. VII., figs. 2 - 2 d.) 
 
 Columnopora cribriformis, Nicholson, Geol. Mag., new sen, vol. i. p. 253, fig. i, 
 1874; Pal. Ohio, vol. ii. p. 186, PL II., figs. 8-8 b, 1875; Second Rep. 
 Pal. Ont, p. 25, 1875. 
 
 Spec, Char. Corallum forming hemispheric or pyriform 
 masses, which vary in diameter from ten lines to half a foot 
 or more, and in height from eight lines to three or more inches. 
 Corallites spreading from the base of attachment, essentially 
 polygonal, and for the most part in close contact, their walls 
 thick and fused together; occasionally becoming subcircular, 
 and partially separated by narrow interspaces as their mouths 
 are approached. Calices rounded or distinctly polygonal, aver- 
 aging one line and a half in diameter, smaller ones being often 
 intercalated here and there among those of ordinary dimen- 
 sions, their margins thick and crenulated by the septa. Septa 
 about twenty in number, more or less, in the form of strong 
 longitudinal ridges, which pass but a short distance inwards to- 
 
GENERA OF FAVOSITID&. 165 
 
 wards the axis of the visceral chamber. Mural pores large, 
 oval, arranged in longitudinal rows between the septa, and 
 separated by intervals as a rule much less than their own 
 diameter. Tabulae numerous, complete, flexuous, often uniting 
 with one another, generally about eight in the space of two 
 lines. 
 
 Obs. The above description is based upon specimens from 
 the Cincinnati group of Ohio, as regards its essential features ; 
 though, as regards one or two characters, I have had in view 
 examples from the corresponding formation in Canada, which 
 I believe to belong to the same species. Thus, in the Canadian 
 examples, the tubes are more liable to show a circular form, 
 and to be at times partially separated near their mouths, than 
 is the case with those from Ohio. On the other hand, the 
 latter usually show polygonal and closely-contiguous tubes. 
 Having fully discussed the structure of this species in dealing 
 with the genus, I need only add that it would seem probable 
 that the Columnopora (Houghtonia) Httronica of Rominger 
 (Foss. Cor. of Michigan, p. 17, PL III., figs. 3 and 4) is really 
 identical with Columnopora cribriformis, Nich. As, however, 
 Dr Rominger's description differs in some important respects 
 from that of the type-species as here given, and as I have not 
 had the opportunity of examining the specimens upon which 
 his account is based, I shall in the meanwhile consider it as a 
 separate species. 
 
 Formation and Locality. In the Cincinnati formation, South- 
 western Ohio. Rare in the corresponding formation (Hudson 
 River group) of the Credit River, Ontario. 
 
 Genus AR^EOPORA, Nich. and Eth. jun., 1879. 
 (Fig. 24.) 
 
 Gen. Char. Corallum massive, Favositiform, of polygonal 
 corallites, which radiate outwards from an imaginary axis to 
 open upon the free surface of the colony. Under surface 
 
1 66 TABULATE CORALS. 
 
 covered by an epitheca (?). The corallites are firmly united 
 by their walls, which are extensively perforated by apertures 
 which place the visceral chambers of contiguous tubes in direct 
 communication. Septa trabecular, often irregularly divided, or 
 anastomosing at their free ends. Tabulae rudimentary, repre- 
 sented only by occasional horizontal trabeculse. No columella, 
 nor ccenenchyma. 
 
 Obs. This genus is founded upon a remarkable specimen 
 belonging to the " Daintree Collection " of corals, from the 
 Devonian or Carboniferous deposits of Queensland, descrip- 
 tions of which will shortly be published by Mr R. Etheridge, 
 jun., and myself. Pending the publication of our joint memoir, 
 I shall simply avail myself here of the permission of my col- 
 league to briefly discuss the characters and affinities of the 
 genus Arceopora, as deduced from the only species with which 
 we are as yet acquainted, and which we propose to name 
 A. Aiistralis. 
 
 The corallum in our specimen of Arczopora Australis might 
 at first sight be taken for that of any of the larger and more 
 massive species of Favosites (such as F. hemispherica, Yand. 
 and Shum.) ; though even to the naked eye the absence of dis- 
 tinct tabulae and the cribriform or porous condition of the walls 
 are striking features. The height of the specimen (which is 
 an imperfect one, and is not only silicified, but is likewise thor- 
 oughly infiltrated with silica) is rather more than three inches,, 
 and its greatest width something over four inches. Its form 
 is pyriform, the narrow base having evidently been attached 
 to some foreign body, while the under surface was almost cer- 
 tainly covered with an epitheca, of which no traces now remain. 
 The calices must have opened over the whole of the convex 
 upper surface, but none of them are preserved in the example 
 before us. The corallites radiate with a graduated divergence 
 from the imaginary axis of the colony, and their form is reg- 
 ularly prismatic or polygonal, as in Favosites. This character 
 is much more perceptible to the eye, or when the surface is 
 examined with a lens, than it is when thin sections are inves- 
 
GENERA OF FA VOSITID^E. 
 
 167 
 
 tigated under the microscope, as it is to some extent masked in 
 the latter case by the broken and cribriform character of the 
 walls. The average diameter of the corallites is about two- 
 thirds or three-fourths of a line. The tubes are completely in 
 contact, and the walls of contiguous corallites are undistinguish- 
 ably amalgamated (fig. 24, A and B). Thin sections, whether 
 
 Fig. 24. A, Part of a transverse section of Araopora Australis, Nich. and Eth. jun. , en- 
 larged eight times, showing the trabecular septa and porous walls ; B, Part of a vertical 
 section of the same similarly enlarged, showing the cribriform character of the walls, the 
 septa, and the rudimentary tabulse. Devonian (?), Queensland. (Daintree Collection). 
 In these figures the matrix, which is really transparent, is represented as if opaque. 
 
 transverse or vertical, show that the walls of the tubes are 
 extensively porous and cribriform (fig. 24, A and B), being 
 pierced by numerous apertures, which place the visceral cham- 
 bers in direct communication. Transverse sections, further, 
 serve admirably to show the character of the irregular trabec- 
 ular septa, some of which are short and spiniform, while others 
 divide at their ends, or even unite with their neighbours. Ver- 
 tical sections show that the septa are upon the whole placed in 
 longitudinal rows, and they exhibit in addition occasional hori- 
 zontal trabeculse (fig. 24, B), which may be regarded as of the 
 nature of rudimentary tabulae. 
 
 From a consideration of the above characters, it cannot be 
 doubted that we have to deal in Ar&opora with a genuine 
 
1 68 TABULATE CORALS. 
 
 " Perforate " coral, which, however, is closely allied to the 
 Favositidce, and may be best placed in this family rather than 
 in any of the more regular groups of the Perforata. By the 
 characters of its walls and septa the genus presents certain 
 alliances with the Poritidce, but its general form and aspect are 
 those of a Favosites, and the presence of rudimentary tabulae 
 would still further confirm the view here taken. Among the 
 genera of the Favositidce, Arceopora finds its nearest ally in the 
 Lower Silurian genus Cohimnopora, Nich., which it nearly re- 
 sembles in form and habit. It is distinguished from the latter, 
 however, by the less regularly perforate character of its walls, 
 by the rudimentary condition of its tabulae, and by the irregu- 
 larly-dividing and trabecular septa. I am unable to institute 
 any comparison between Arceopora and the Cretaceous Kon- 
 inckia, E. and H., but the septa of the latter seem to be 
 merely spiniform (six in number), and the tabulae are said to 
 be well developed and complete. 
 
 The geological horizon of Arceopora Australis, Nich. and 
 Eth. jun., is not quite certain, but it occurs in deposits of 
 Devonian or Carboniferous age (the former most probably) 
 in Queensland. 
 
 Genus STENOPORA, Lonsdale, 1844. 
 
 (Appendix to Darwin's Volcanic Islands, p. 161, 1844, and in Strzelecki's 
 Phys. Hist, of New South Wales, p. 262, PL VIII., 1845.) 
 
 Tubulididia, Lonsdale, in Murchison's Geol. of Russia, p. 601 (note), 1845. 
 (Non Stenopora, M'Coy, Brit. Pal. Foss. p. 24, 1851.) 
 
 Gen. Char. Corallum ramose, or sublobate, rooted below, and 
 composed of tubular corallites, which are nearly vertical in the 
 centre of the branches, and radiate outwards from an imaginary 
 axis to open on all points of the free surface. Corallites in 
 the centre of the branches, polygonal, thin-walled, and more or 
 less completely in contact; but in the outer curved portion 
 of their course, more or less cylindrical, and annulated by 
 
GENERA OF FAVOSITID^E. 169 
 
 periodical ring-shaped thickenings, which are placed at cor- 
 responding levels in contiguous tubes, in such a manner as 
 to leave vacant spaces between the intervening unthickened 
 portions. Visceral chamber in the outer portion of the tubes 
 alternately contracted and dilated in correspondence with the 
 periodical thickening of the walls of the corallites just spoken 
 of; but open and subpolygonal in the axial portion of the cor- 
 allum. Septa obsolete. Tabulae remote, usually placed at cor- 
 responding levels in contiguous tubes. Mural pores of small 
 size, not numerous, and irregularly distributed. 
 
 History. The genus Stenopora, Lonsdale, was first described 
 by its author in a note in Darwin's ' Volcanic Islands/ but was 
 more fully defined in Strzelecki's ' Physical History of New 
 South Wales ' as follows : " A ramose spherical or amorphous 
 tubular polypidom ; tubes polygonal or cylindrical, radiated 
 from a centre or an imaginary axis, contracted at irregular 
 distances, but in planes parallel to the surface of the speci- 
 men ; tubular mouths closed at final (?) period of growth ; 
 ridges bounding the mouths granulated or tuberculated ; addi- 
 tional tubes interpolated." 
 
 It is quite clear, as properly pointed out by Dana (U.S. 
 Expl. Exped. Zoophytes, p. 537, 1848), that the above generic 
 diagnosis is insufficiently characterised i 1 and to this must be 
 ascribed the great confusion in which the genus has subse- 
 quently become involved. Professor Dana, in the work just 
 quoted, defines the genus as follows : 
 
 " Internal structure of corallum fine prismatic; cells of sur- 
 face minute, subangular, contiguous ; zoophytes glomerate or 
 ramose ; surface often small-verrucose." 
 
 This definition, also, really adds nothing to our knowledge of 
 the actual structure of the genus ; and it is therefore no matter 
 
 1 In the original description of Stenopora in Darwin's 'Volcanic Islands,' Mr 
 Lonsdale does give a character of generic value viz., the gradual closure of the 
 mouths of the tubes by the deposition of calcareous matter on the interior of the 
 wall, giving rise to what he regarded as periodical " constrictions " of the tubes ; 
 though these are really periodical " thickenings " of the wall, it being only the 
 visceral chamber that is " constricted." 
 
170 TABULATE CORALS. 
 
 of surprise to find that Milne-Edwards and Haime at first 
 accept the genus in part (Brit. Foss. Cor. Intr., p. Ixi, 1850), 
 with the clearly insufficient definition that the corallum is 
 " very similar to Chatetes" but has " small styliform pro- 
 cesses at the angles of the calices ; " and then immediately 
 afterwards (Pol. Foss. des Terr. Pal., p. 261, 1851) merge 
 the genus with Chcetetes, Fischer. 
 
 Mr Lonsdale's definition of Stenopora was founded (as also 
 Professor Dana's) upon specimens derived from Australia and 
 Van Diemen's Land ; and, so far as known, all the examples 
 in the hands of these observers were of Devonian or Carboni- 
 ferous age. At this point, however, the history of the genus 
 which need not here be followed out in detail became compli- 
 cated by the reference to it by Professor M'Coy of a number 
 of Silurian Corals (Brit. Pal. Foss., p. 24, 1851). The defini- 
 tion of Stenopora given by M'Coy is as follows : 
 
 " Polypidom polymorphous, composed of round or polygonal 
 tubes radiating from an imaginary axis to the surface, where 
 the bounding ridges are tuberculated ; young tubes interpolated 
 by lateral budding between the old ; tubes constricted at irreg- 
 ular distances in planes parallel with the surface, and partially 
 closed at the orifice by a concave diaphragm perforated in the 
 centre ; no connecting tubuli, nor foramina." 
 
 The only species unhesitatingly referred to the genus by 
 M'Coy is one which he identifies specifically with the Calamo- 
 pora fibrosa of Goldfuss (Petref. Germ., PI. XXVIII., figs. 3 a, 
 3 b, 1829). The examples upon which Goldfuss founded this 
 species were derived from North America ; and as I have not 
 had the opportunity of examining the originals, I can only 
 say that the figures of the German palaeontologist would pass 
 very well as figures of such a species of Stenopora as S. ovata, 
 Lonsd. Calamopora fibrosa, Goldf., was, however, subsequently 
 referred by Milne-Edwards and Haime to Favosites, under the 
 name of F. fibrosa (Pol. Foss. des Terr. Pal., p. 244), and the 
 species was stated to occur in the Lower and Upper Silurian, 
 and also in the Devonian, in Britain, Europe, and North 
 
GENERA OF FAVOSITID&. 171 
 
 America. I have never myself been so fortunate as to meet 
 with any specimens which I could refer without doubt to 
 Favosites fibrosa, Goldf. sp., as denned by the eminent French 
 authors above referred to ; and I am therefore quite unable 
 to express any opinion as to its affinities. It seems, however, 
 quite certain that the corals described by Professor M'Coy 
 under the name of Stenopora fibrosa, Goldf. sp., have in reality 
 no relations whatever with the true Stenopora of Lonsdale. On 
 the contrary, it is almost certain that they belong to the genus 
 Chcetetes, Fischer, or to Monticulipora, D'Orb., as ordinarily 
 understood ; and the same may be pretty confidently asserted 
 of all the examples of Stenopora which have subsequently been 
 quoted by various writers as occurring in the Silurian deposits 
 of various parts of the world. At the same time, though I 
 think that we have at present no actual evidence of the exist- 
 ence of any species of Stenopora in the Silurian rocks, it is 
 quite possible that a more extended investigation may yet 
 show some of the so-called Monticuliporce of the Silurian to be 
 really referable to the former genus. We shall subsequently 
 see, indeed, that there are certain of the Silurian Monticuli- 
 porce which, except in the apparent absence of " mural pores," 
 make a very close approach in structure to Stenopora. 
 
 It is quite clear, further, that with the available information 
 as to the structure of the genus Stenopora, Lonsd., it was im- 
 possible to establish any satisfactory generic distinction between 
 this type and Chcetetes or Monticulipora ; and this view was the 
 one finally adopted by Milne-Edwards and Haime, and subse- 
 quently followed by myself (Quart. Journ. Geol. Soc., vol. xxx. 
 p. 499, 1874). To this opinion I should have been still in- 
 clined to adhere; but Professor De Koninck has shown that 
 one of the species described by Lonsdale (viz., S. ovata) pos- 
 sesses perforated walls, and is therefore fundamentally separ- 
 ated from the entire family of the Ck&ttfidcB, Indeed he refers 
 the species just mentioned to the genus Favosites itself. I have, 
 moreover, recently had the opportunity of examining a tolerably 
 extensive series of examples of Stenopora, mostly collected by 
 
1 72 TABULATE CORALS. 
 
 Mr R. L. Jack, F.G.S., in Queensland ; and having made a 
 careful microscopical examination of the genus by means of 
 thin sections, I am able not only to confirm De Koninck's 
 reference of the genus to the a&Qsitid& % but to show further 
 that its characters are entirely peculiar, and such as to separate 
 it generically from all the other members of the family. The 
 specimens in question formed part of a collection of Australian 
 corals which will shortly be described by Mr Robert Etheridge, 
 jun., and myself; and it is to the kindness of my colleague that 
 I owe the permission to use here the previously given generic 
 diagnosis, as well as the following observations upon the struc- 
 ture of Stenopora. Pending the publication of our joint memoir, 
 however, I shall not add in this place any descriptions of the 
 species, merely remarking that the forms which we have ex- 
 amined appear to be referable to three species, one of which 
 is identical with 5. ovata, Lonsd., while a second seems to be 
 new (S. Jackiiy Nich. and Eth, jun.), and the third is not in a 
 condition to admit of definite specific identification. 
 , Obs. Taking 6 1 . ovata, Lonsd., as the basis of the following re- 
 marks, the corallum in Stenopora is usually more or less branched ; 
 but the branches may be so thick, and may so extensively coal- 
 esce, that its general form becomes that of a lobate mass. The 
 corallites (fig. 25, A) radiate in all directions from an imagin- 
 ary axis, and present very different appearances in the central 
 and circumferential portions of the corallum respectively. In 
 the axial portion of the branches the tubes are nearly vertical, 
 have thin walls, are essentially polygonal or prismatic in shape, 
 and are nearly or quite in contact with one another throughout. 
 As they pass upwards, the tubes gradually diverge, coming at 
 last to be nearly horizontal, and continuing in this direction for 
 some distance, till they at last open upon the surface. There 
 is thus an outer zone of the corallum in which the corallites are 
 nearly transverse to the axis of the branches, and within this 
 zone they present all their peculiar features. In this region, 
 namely, the corallites (fig. 25, B) assume a generally cylindrical 
 appearance, owing to the fact that their walls are thickened at 
 
GENERA OF FAVOSITID^E. 
 
 '73 
 
 very short intervals by annular accretions of growth, the por- 
 tions of the tube between these retaining their normal diameter. 
 As these thickened portions of the corallites are placed at cor- 
 
 Fig. 25. A, Portion of a branch of Stenopora Jackii, Nich. and Eth. jun., split open, of the 
 natural size ; B, Portion of the same enlarged, showing the annulations of the tubes in their 
 outer portions ; c, A few of the tubes of the same still further enlarged, showing the 
 
 > mural pores. Permo-Carboniferous formation, Queensland. 
 
 responding levels in all the corallites, it follows that the tubes 
 are actually in contact with one another at these points only, 
 and that they are separated by ring-like spaces corresponding 
 to all the unthickened segments of the tubes. 
 
 Thin sections of the corallum bring to light the peculiarities 
 just mentioned, along with others, the true significance of which 
 cannot at present be ascertained. Thus, if we take a trans- 
 verse section of a branch, and examine its central portion, 
 where the nearly vertical tubes are cut across approximately at 
 right angles to their course, we find that the corallites (fig. 26, B) 
 differ in no essential respect from those of Favosites as re- 
 gards their general structure. Each possesses its own wall, 
 which is not excessively or abnormally thickened, and the 
 boundary between contiguous tubes is clearly marked by a 
 dark line. The tubes in this portion of the corallum are, more- 
 over, regularly polygonal, and are, as a rule certainly, in close 
 contact. If, on the other hand, we take a section tangential to 
 the branch, and just below its surface, we have the corallites cut 
 transversely across in the horizontal and annulated portion of 
 their course, and the appearances presented are very different 
 to the above. The tubes still appear to be in close contact and 
 to be polygonal, each being bounded externally by a well- 
 
174 
 
 TABULATE CORALS. 
 
 defined dark line ; but the appearances of the area within this 
 .boundary-line vary according as the section cuts the tubes at 
 the level of their thickened portions, or at that of the unthick- 
 
 Fig. 26. A, Two tubes of Stenofora ovata, Lonsd., cut transversely across their thickened 
 portions, and showing the contraction of the visceral chamber by an annular deposit of 
 sclerenchyma, which is not in contact with the wall on one side ; B, Two tubes of the 
 same from the axis of a branch, cut transversely, showing their thin walls and polygonal 
 form ; c, Portion of a tube of the same cut longitudinally, showing the thickening of 
 the wall, the tabulae, and one of the mural pores. Enlarged twenty-five times. Permo- 
 Carboniferous, Queensland. 
 
 ened intervals between the latter. In the former case, the 
 visceral chamber (fig. 26, A, and PI. IX., fig. i a) is seen to be 
 greatly contracted, and to be reduced to a comparatively small 
 rounded or subpolygonal central tube, which is in turn sur- 
 rounded by a thickened ring of sclerenchyma, which usually 
 shows distinct traces of its being composed of successively- 
 deposited concentric laminae. In the latter case there is still a 
 ring of sclerenchyma within the dark outer polygonal boundary, 
 but this ring is of small thickness comparatively, and the cen- 
 tral tube is wide and open the general appearances being on 
 the whole like those presented by cross-sections of the tubes in 
 the axial portion of the corallum. In both the above cases, 
 however, whether the section cut the corallites across their 
 thickened or their unthickened portions, there are two pheno- 
 mena observable which I am at present quite unable to explain. 
 One of these consists in the fact that the ring of sclerenchyma 
 within the corallites is never in contact with the outer polygonal 
 
GENERA OF FAVOSITID^E. 175 
 
 wall for more than one half or two-thirds of its circumference, 
 being separated from the latter throughout the remaining part 
 of the tube by a distinct and conspicuous interspace, which is 
 filled in the fossil with transparent calcite. Not only is this 
 partial interspace between the inner ring and the outer wall 
 (PI. IX., fig. i a, and fig. 26, A) apparently always present, but 
 it seems to be always situated upon the same side of all the 
 corallites in any particular section. The other point that is 
 difficult to understand is how the outer dark walls of the coral- 
 lites should appear in tangential sections to be always in close 
 contact, seeing that an examination of the exterior of the tubes 
 with a lens shows that they are only in contact along the thick- 
 ened planes in which rings are developed, and are separated by 
 distinct intervals in the spaces between these. Moreover, in 
 many parts of tangential sections the corallites exhibit few 
 features that would satisfactorily separate them from similar 
 sections of the tubes of certain Monticulipora, though they 
 usually have exceptionally thick walls, and also often exhibit a 
 thin dark ring a little within the true wall, and concentric with 
 the latter. There are also some other phenomena occasionally 
 observable which it is extremely difficult to explain ; and it 
 seems clear that the precise structure of this curious type must 
 remain to some extent unelucidated until a large series of speci- 
 mens can be microscopically investigated. 
 
 Longitudinal sections of the tubes (fig. 26, c, and PI. VIII., 
 fig. i) show the periodical annular thickenings of the tubes 
 in a very instructive manner, and show that these are really 
 thickenings of the wall, projecting both externally and internally, 
 and that it is therefore incorrect to regard the tubes as being 
 " periodically constricted " this phrase applying only to the 
 visceral chamber. In fact, the longitudinal section of the wall 
 has a regularly moniliform appearance, due to its successively 
 traversing thickened and unthickened segments of the tube. 
 Sections of this kind also show that there exist remote and 
 complete tabulae, which are usually placed at approximately 
 corresponding levels in all the corallites of a single colony. 
 
176 TABULATE CORALS. 
 
 Lastly, these sections occasionally show mural pores, though 
 these structures can be best made out by a microscopic exami- 
 nation of the exterior of the tubes, when they are found to be 
 present in the form of small, circular, irregularly-distributed 
 apertures. It may be added that long sections show the same 
 curiously puzzling feature as do tangential slices namely, that 
 the corallites are apparently in contact throughout their length, 
 whereas macroscopic examination shows them to be clearly free 
 over the unthickened segments of the tube. 1 
 
 So far as can be at present ascertained, the species properly 
 belonging to Stenopora, Lonsd., as now worked out, are all 
 confined to the Carboniferous or Permo-Carboniferous periods, 
 there being some uncertainty as to the precise horizon of some 
 of the deposits which have yielded specimens of this type. So 
 far as known, also, the species of the genus are confined to 
 Australia and Van Diemen's Land. It cannot be said that any 
 species of the genus has been certainly identified in the Silurian 
 rocks, and all the Silurian corals which have been at various 
 times referred here must in the meanwhile be placed under 
 Monticulipora or Chcetetes pending their complete examination 
 by microscopic methods. The internal structure of Stenopora, as 
 I have here described it, is such as to fundamentally separate 
 the genus from either Ch&tetes or Monticulipora', but I am 
 unable to say how far a mere examination of the surface with 
 a lens would enable an observer to separate a specimen of the 
 first from one belonging properly to either of the latter genera. 
 None of my examples, in fact, show the surface-characters in 
 a satisfactory manner ; but so far as I can judge, the general 
 
 1 Since the foregoing has been written, examples of Stenopora Tasmaniensis, 
 Lonsd., S. crinita, Lonsd., and of a third form apparently referable to S. informis, 
 Lonsd., have been carefully examined by Mr R. Etheridge, jun., and myself. The 
 phenomena which these present v/ill be elsewhere recorded by us, and it will be 
 sufficient here to say that all the above species are true Stenoportz, though the two 
 last are massive, and in many respects widely unlike S. ovata in general appear- 
 ance. All of them, however, possess the peculiar fibrous thickenings of the walls of 
 the tubes in parts, and must therefore be regarded as congeneric with S. ovata. 
 They show, nevertheless, many very singular features, the two last in particular not 
 only differing considerably from S. ovata, but also differing in important characters 
 from one another. 
 
GENERA OF FAVOSITID^E. 177 
 
 aspect of the calices is very similar to that of some Monti- 
 ciUiporce, and I should therefore doubt if simple inspection of 
 the exterior would enable one to identify a specimen of Steno- 
 pora. Certainly the presence of spines or tubercles on the lips 
 of the calices even if a constant character cannot be sup- 
 posed to have anything beyond a mere specific significance. 
 I shall, however, have occasion to show hereafter that the 
 spines and calicine tubercles of certain Stenoporce and Monti- 
 culiporce are not mere surface-ornaments, but that they in 
 reality are produced by the metamorphosis of a peculiar and 
 special series of corallites. 
 
 Genus RCEMERIA, Milne-Edwards and Haime, 1851. 
 (Pol. Foss. des Terr. Pal., p. 253.) 
 
 The genus Rcemeria was founded by Milne-Edwards and 
 Haime for the reception of the single species R. infundibuli- 
 fera, the Calamopora infimdibulifera of Goldfuss (Petref. Germ., 
 t. i. p. 78, PL XXVII., fig. i, 1826). I reproduce here the 
 description given by these authorities both of the genus and 
 species : 
 
 Genus RCEMERIA. " Gorallum forming a rounded mass, the 
 corallites united by their walls, the tabulae infundibuliform." 
 
 Species, Roemeria infundibulifera, Goldf. " Corallum massive, 
 sublobate ; the corallites unequal, intimately united by their 
 walls at certain places, although free near their summits ; calices 
 in general polygonal, of a diameter of two or three millimetres. 
 There are traces of thin and equal-sized rudimentary septa. A 
 vertical section shows that there are tolerably regular and 
 numerous tabulae, in the form of funnels let one into the other. 
 We do not know if mural pores are actually present." 
 
 The brevity of the above diagnosis is sufficient to show that 
 Milne-Edwards and Haime possessed but a partial knowledge 
 of the structure of the above species and of the genus which 
 they founded upon it ; nor is any additional light to be derived 
 
 M 
 
178 TABULATE CORALS. 
 
 from an examination of the figure given by Goldfuss, except that 
 this indicates a coral in many respects very unlike the normal 
 forms of Favosites. I am unable personally to give any fresh 
 information as to the structure or affinities of this coral ; but Mr 
 George J. Hinde, who has lately examined the original speci- 
 men in the Bonn Museum, permits me to say that in his opinion 
 the relationships of this peculiar type, so far as they can be 
 determined without actual sections, are rather with Syringopora 
 than with Favosites. The walls of the corallites are very thick, 
 and the tubes (as noted by Milne-Edwards and Haime) are 
 actually not in contact near their mouths, while there is no 
 positive evidence as to the existence of mural pores. The 
 tabulae also are simply invaginated, without being so bent down- 
 wards in the centre as to give rise to a median tube ; so 
 that, on the whole, the corallum may " be compared with that 
 of a Syringopora, in which the connecting-processes are absent 
 and the corallites are in close contact." On the other hand, 
 my friend Mr Hinde has had the great kindness to allow me 
 access to his specimens of a most remarkable Favositiform 
 coral, which he has collected in the Niagara Limestone of 
 Canada, and which in some respects agrees with the published 
 description of Rcemeria, E. and H.; and I am further indebted 
 to him for the permission to make use here of the following 
 condensation of its characters, drawn from the MS. of a paper 
 which he is about to publish on the subject. 
 
 Genus SYRINGOLITES, Hinde, 1879. 
 (Fig. 27.) 
 
 Gen. Char. Corallum composite, forming flattened expan- 
 sions, with a basal epitheca, in general appearance resembling 
 Favosites Gotklandica, Lam. Corallites in close contact through- 
 out, prismatic, thin-walled, with one or more vertical rows of 
 mural pores on each prismatic face. Tabulae annular, curved 
 so as to be concave upwards, and depressed centrally so as to 
 give rise to a vertical median tube, which may be continuous 
 
GENERA OF FA VOSITID^E. 
 
 179 
 
 or may be crossed by an occasional partition, and which runs 
 down the centre of the visceral chamber of each corallite, and 
 possesses non-perforate walls. Septa represented by crenula- 
 tions of the walls of the corallite, which are continued over the 
 upper surfaces of the tabulae in the form of a series of short 
 spines or tubercles, arranged in radiating rows, till they ulti- 
 mately disappear in the depths of the central tube (fig. 27). 
 
 This extraordinary genus is only known by a number of 
 silicified specimens, in a state of beautiful preservation, col- 
 lected by Mr George J. Hinde in the Niagara Limestone of 
 Manitoulin Island, Canada, and about to be fully described by 
 him under the name of Syringolites Huronensis^ Under these 
 
 Fig. 27. A, A fragment of a colony of Syringolites Huronensis, Hinde, of the natural size ; B, 
 A single calice of the same, enlarged eight times, showing the central tube, and radiating 
 lines of septal tubercles ; C, Part of a corallite of the same, split open, and enlarged six 
 times, showing the composition of the central tube out of invaginated tabulae ; D, Part of 
 a corallite of the same, viewed from the exterior and enlarged six times, showing the 
 mural pores. Niagara Limestone, Manitoulin Island, Ontario. Coll. George J. Hinde. 
 
 circumstances, it would not be proper for me to do more than 
 to say that, after a careful examination of the specimens col- 
 lected by this indefatigable observer, I am able to entirely 
 corroborate his views as to the structure of the genus, while I 
 may justifiably add a few general remarks bearing upon the 
 connection between this new type and those which have been 
 previously considered. 
 
 In the first place, then, it is clear that in Syringolites, Hinde, 
 we are presented with a coral closely allied to Favosites proper, 
 as shown by its general form, its prismatic corallites, intimately 
 
 1 Since the above was written, Mr Hinde has published his description of S. 
 Huronensis (see Geol. Mag., Dec. ii., vol. vi. p. 244, June 1879). 
 
i8o TABULATE CORALS. 
 
 united by their walls, and its possession of rudimentary spini- 
 form septa, of tabulae, and of mural pores. In the second place, 
 we have here a coral which really fulfils Goldfuss's ideal of 
 Calamopora " diaphragmatibus transversis, e siphone proli- 
 fero ; " if it were at all possible to revive this name with justice 
 or advantage. It is, however, quite certain that not one of the 
 forms included by Goldfuss under the name of Calamopora 
 not even his Calamopora (Rcemeria) infundibulifera really 
 possesses a central siphonal tube, formed by the junction of a 
 vertical series of funnel-shaped depressions of the tabulae in 
 the middle line. Mr Hinde's specimens, however, place it 
 beyond a doubt that, in his Syringolites Huronensis, we have 
 precisely such a form ; and we are thus presented with a true 
 member of the FavositicUe^ which, in one of the most striking 
 points of its organisation, offers a distinct approximation to 
 certain of the forms included under the genus Syringopora. It 
 need only be added here that the present form is generically 
 distinguished from all those ordinarily ranged under Syringo- 
 pora, not only by the close union of the polygonal corallites 
 and the total absence of connecting-processes, but also by the 
 possession of mural pores in all respects resembling those 
 found in the type-species of the genus Favosites. 
 
 Genus LACERIPORA, Eichwald, 1860. 
 (Lethsea Rossica, p. 490.) 
 
 Gen. Char. " Corallum thick, elongated, curved, ramose, of 
 almost cylindrical branches ; the calices angular, unequally- 
 sized, united with one another [by their walls], and provided 
 with two, three, or more rudimentary vertical lamellae. The 
 corallites radiate regularly from a cellular or porous central 
 axis, and are intersected by thick tabulae, which are placed at 
 the same level in different tubes, so as to form a succession of 
 superimposed layers. The margins of the calices are crenu- 
 lated or uneven ; they may or may not be provided with rudi- 
 
GENERA OF FAVOSITID&. 181 
 
 mentary vertical lamellae. The corallites differ from one an- 
 other in size and shape, and are so amalgamated by their walls 
 that no distinct lines of demarcation can be distinguished be- 
 tween them " [" elles se soudent ensemble et forment des murs 
 confluents, de sorte qu'on ne peut pas les distinguer les unes 
 des autres "]. 
 
 Obs. I am not acquainted with any example of this genus, 
 and can do nothing more than give the above translation of 
 M. Eichwald's description of it. For the clearer understanding 
 of its characters I have likewise reproduced Eichwald's figures 
 (PI. VII., figs. 3 - 3 b], which, if reliable, would seem to indi- 
 cate a distinct generic type. These figures present us with a 
 ramose corallum, with a general resemblance to the dendroid 
 forms of Pachypora or Favosites ; with very thick-walled coral- 
 lites, which are furnished with a small number of strong mar- 
 ginal septa (PI. VII., fig. 3 a). The drawing given on PL 
 VII., fig. 3 b, is said by Eichwald to be the " coupe transver- 
 sale," and it doubtless is the transverse section ; but it repre- 
 sents the outermost portion of such a section, where the tubes, 
 as they diverge outwards, become nearly horizontal, so that 
 we really see the corallites cut longitudinally. In this section 
 we see that the tubes in accordance with the description given 
 by Eichwald are intersected by thick tabulae, placed at cor- 
 responding levels in contiguous tubes. 
 
 There is nothing in Eichwald's description or figures which 
 would lead to any safe conclusion as to the systematic position 
 of Laceripora ; and no allusion whatever is made to the exist- 
 ence of mural pores. I have therefore provisionally included 
 the genus in the Favositidce, simply in deference to the opin- 
 ion of Dr Lindstrom, who is probably acquainted with actual 
 examples of the genus, and who states that it is " nothing more 
 than a highly-perforated Favosites " (Ann. Nat. Hist., ser. 4, 
 vol. xviii. p. 12, 1876). 
 
 The only known species of the genus is the Laceripora crib- 
 rosa of Eichwald, which is stated to occur in the "grauwacke" 
 (Upper Silurian), and also in the Carboniferous formation. 
 
1 82 TABULATE CORALS. 
 
 Genus NYCTOPORA, Nicholson. 
 
 Gen. Char. Corallum composite, massive, of polygonal 
 corallites, which radiate from the base of the spheroidal coral- 
 lum, to open on its upper surface, and are in complete contact 
 throughout their entire extent. Walls of the corallites thin, 
 and so completely amalgamated that no trace whatever of the 
 original lines of division between the tubes can be detected. 
 Mural pores numerous, small, in more than one series, occupy- 
 ing the sulci between the septa. Septa in the form of marg- 
 inal vertical ridges, which extend along the whole length of 
 the tubes, from ten to fifteen in number in each corallite, 
 not divisible into an alternating series of longer and shorter 
 lamellae. Tabulae numerous, complete, horizontal. 
 
 Obs. I have been obliged to establish this genus for the 
 reception of a coral from the Trenton Limestone of Canada, 
 which I have previously regarded as probably identical with 
 Cohimnaria Goldfussi, Bill. In its general form and aspect 
 this coral, in fact, is entirely similar to Columnaria Halli, mihi 
 (C. alveolata, Bill.) ; and it does not differ in any superficially 
 obvious character from the typical species of Columnaria (C. 
 alveolata, Goldf., and C. calicina, Nich.), except in the marginal 
 and comparatively rudimentary condition of the septa. Thin 
 sections, however, place it beyond a doubt that the walls of the 
 present form are perforated by mural pores, and that the coral 
 in question must be placed in the Favositidce. Whether or not 
 the walls of Columnaria (?) Halli are likewise perforate is a point 
 which at present I cannot determine, though I am inclined to 
 think that in this form also mural pores are present. If this 
 conjecture should be ultimately established, then this well- 
 known form (the Columnaria alveolata of American palaeon- 
 tologists) will also have to be removed to the genus now 
 under consideration. 
 
 The corallum in the only certainly ascertained species of 
 Nyctopora is in the form of spheroidal or pyriform masses, 
 
I GENERA OF FA VOSITID^E. 183 
 
 composed of polygonal and closely -contiguous corallites, the 
 walls of which are not only in contact, but are undistinguish- 
 ably amalgamated with one another (PI. IX., figs. 3-3 c], 
 The corallites radiate from the base of attachment, the lower 
 surface being probably covered with an epitheca, and the 
 calices opening upon the convex upper surface (PL IX., 
 fig. 3). The calices are polygonal, with moderately thick 
 margins, which are crenulated by the rudimentary septa (PI. 
 IX., fig. 3 c). Transverse sections (PI. IX., fig. 3 a) show 
 that the walls of contiguous corallites are completely fused 
 with one another, no trace whatever of the original line of 
 demarcation between neighbouring tubes being recognisable 
 under the microscope. Sections of this kind also show the 
 short marginal septa, to the number of from eight to twelve 
 or more in each tube ; while occasionally a mural pore is 
 laid open, connecting the cavities of contiguous corallites 
 directly with one another. Vertical sections (PI. IX., fig. 
 3 b) show that there are numerous thin, horizontal, and 
 complete tabulae ; and in parts where the section more 
 or less nearly coincides with the plane of the walls of any 
 of the tubes, we observe numerous unmistakable mural 
 pores. These apertures differ in no respect from the mural 
 pores of Favosites> except that they are perhaps proportion- 
 ately smaller, and do not seem to obey any regular law of 
 distribution. 
 
 So far as known, this genus is confined to the Trenton Lime- 
 stone in North America, and it affords a very interesting link 
 between the Favositidce and the Columnariadce. It differs 
 from Favosites in the lamellar condition of the septa, which, 
 though rudimentary, are never spiniform ; and in the more 
 minute size and apparently irregular distribution of the mural 
 pores. On the other hand, though agreeing with Columnaria, 
 Goldf., in its general structure and appearance, and especially 
 in the character of its septal apparatus, it is fundamentally 
 distinguished from the latter (as our present knowledge stands) 
 by the perforated condition of its walls. 
 
1 84 TABULATE CORALS. 
 
 Nyctopora Billingsii, Nicholson. 
 
 (PL IX., figs. 3 - 3 c.) 
 Columnaria GoMfussi, Nicholson, Sec. Rep. Pal. Ont., p. 9, 1875. 
 
 Spec. Char. Corallum forming small spheroidal or pyriform 
 masses, varying from seven lines in diameter and four lines in 
 height, to rather more than an inch and a half in diameter and 
 an inch in height. Corallites prismatic or polygonal, subequal, 
 about three-quarters of a line or rather less in diameter, their 
 walls everywhere contiguous and closely amalgamated. Septa 
 in the form of from eight to twelve or more strong marginal 
 ridges, which run the entire length of the tubes, and project to 
 a very limited extent into the interior of the visceral chamber. 
 Mural pores numerous, minute, circular, apparently not arranged 
 in any definite order. Tabulae horizontal, complete, about six 
 in the space of two lines. 
 
 Obs. As I have discussed the structure of this coral in 
 dealing with the genus Nyctopora, of which it is the only known 
 representative, I have little to add here. The specimens in 
 my possession are all from the Trenton Limestone of Canada, 
 and they were identified by me, from an external examination 
 only (Sec. Rep. Pal. Ont, p. 9), as young examples of Colum- 
 naria Goldfussi, Bill. They agree, indeed, with the descrip- 
 tion of this species (Geol. Surv. Can. Report of Progress for 
 1857, p. 1 66, 1858) in most respects, but the latter is said to 
 form " large amorphous or subglobose masses," with from four 
 to six tabulae in the space of one line, the septa " rudimentary, 
 but distinctly striating the interior walls ; " whereas the present 
 form is always quite small, its tabulae are wider apart, and its 
 septa, though rudimentary, have the form of strong vertical 
 ridges. As it is not known whether or not mural pores are 
 present in Columnaria Goldftissi, Bill., no stress can be laid 
 upon this character ; but their undoubted presence in Nyctopora 
 Billingsii, taken along with the differences above noted, and 
 
GENERA OF FA VOSITID^E. 185 
 
 the fact that Columnaria Goldfussi is believed to belong to the 
 Hudson River formation, would seem to point to the at least 
 specific distinctness of the present coral. If a further examina- 
 tion of C. Goldfussi, Bill., should show it to be possessed of 
 mural pores, then it also must be removed to the genus Nycto- 
 pora. Lastly, there is a close general resemblance between 
 the present form and Columnaria (?) Halli, mihi (the Colum- 
 naria alveolata of American writers), and it is not at all impos- 
 sible that the latter may be shown to have perforate walls, and 
 thus to truly belong to the present genus. 
 
 Formation and Locality. Not uncommon in the Trenton 
 Limestone of Peterboro', Ontario. 
 
 Genus BILLINGSIA, De Koninck, 1876. 
 (Rech. sur les Foss. Pal. de la Nouv. Galles du Sud., p. 75, PI. II., fig. 4.) 
 
 Gen. Char. " Corallum composed of compressed corallites, 
 united by their walls, and communicating freely with one 
 another by means of lateral openings. Calices small, ovate, 
 and furnished with a few septal striae. Tabulae apparently 
 absent." 
 
 Obs. This genus was founded by Professor De Koninck 
 (loc. cit.} for a single species of coral (B. alveolaris], from strata 
 of Devonian age, near Zass, on the Murrumbidgee River, in 
 Australia. Not having seen any examples of the form in 
 question, I can simply reproduce the above generic diagnosis 
 and one of the figures (PI. IX., fig. 4) given by De Koninck. 
 Assuming the correctness of the description given as to which 
 the great experience of this distinguished observer leaves little 
 room to doubt we have to deal in Billingsia with a perforate 
 coral, belonging to the Favositida, but distinguished from the 
 other members of this family by the suppression of the tabulae. 
 The mural pores are apparently numerous and of large size, 
 but they do not seem to have any serial arrangement. Profes- 
 sor De Koninck expresses the opinion that the genus is in- 
 
1 86 TABULATE CORALS. 
 
 termediate between Aulopora and Syringopora \ but it seems 
 hardly possible, with our present knowledge, to arrive at any 
 certain conclusions as to its true systematic position. 
 
 Genus NODULIPORA, Lindstrom, 1873. 
 (Ofversigt af Kongl. Vetensk. Akad. Forhandl., No. 4, p. 14, note, 1873.) 
 
 Gen. Char. " Polyparium turbinatum, totum e nodulis 
 minimis contextum, ceterum et forma et septis Favositarum. 
 Epitheca tenuis, longitudinaliter rugosa. Superficies calycigera 
 lata, plana. Calyces insequales, saepe in radios crescentes, 
 obovati, angusti vel circulares, polygonii et curvi. Muri incom- 
 pleti, perforati. Noduli corpore rotundo, processibus tenuibus 
 inter se conjuncti. Partes inferiores vel primariae polyparii 
 materia calcarea consolidatse. Superficies calycigera processus 
 radiciformes emittit." " Species unica N. acuminata, m. in 
 Dalhem, Gotlandia, reperta." 
 
 Obs. I am not aware that Dr Lindstrom has ever published 
 any further description or any figures of this remarkable form ; 
 and as I am altogether unacquainted with actual specimens, I 
 can add nothing to the above generic diagnosis. Judging from 
 this alone, Nodulipora, Lindst, must be regarded as an 
 aberrant member of the Favositidce, with no marked affinities 
 to any other member of this varied family. 
 
r8 7 
 
 CHAPTER VII. 
 
 COLUMNARIAD.E (LYOPORA AND COLUMNARIA). 
 
 Genus LYOPORA, Nich. and Eth. jun., 1878. 
 (Mon. Sil. Foss. of Girvan, Fasc. i. p. 25.) 
 
 Gen. Char. Corallum composite, massive, forming irregu- 
 larly spherical or pyriform masses, composed of tubular, sub- 
 cylindrical, or subpolygonal corallites, which are more or less 
 completely fused with one another. Walls of the corallites 
 extraordinarily thick and dense, apparently destitute of mural 
 pores. Septa rudimentary, marginal, few in number, having 
 the form of irregular obtuse ridges on the interior of the wall. 
 Tabulae strong and complete. No columella nor ccenenchyma. 
 Obs. The corallum in this genus is chiefly remarkable for 
 the great density of the walls of the corallites, contiguous tubes 
 being separated by partitions which may equal half or more of 
 diameter of the former (PI. IX., figs. 2 and 2 a). Moreover, 
 the walls of neighbouring tubes are completely amalgamated 
 with one another, so that the original boundaries of the coral- 
 lites are either quite irrecognisable, or can only be made out 
 more or less obscurely. Rough fractures, also, invariably 
 expose the interior of the tubes. The corallites are subpoly- 
 gonal or subcircular in shape, and are essentially in contact 
 throughout their entire length. The dense intertubular scler- 
 
1 88 TABULATE CORALS. 
 
 enchyma, however, exhibits very commonly small irregularly- 
 distributed and irregularly-shaped vacuities, which vary much 
 in number in different specimens, or even in different parts of 
 the same specimen. Sometimes they are almost wholly 
 absent, sometimes they are so far abundant that one may 
 count five or six in the wall surrounding one corallite ; while 
 they may be circular, oval, crescentic, or quite irregular in out- 
 line. They are seen both in transverse and vertical sections 
 (PI. IX., figs. 2 and 2 a), and they can often be detected 
 on the surface in the form of pits in the thick margins of 
 the calices. It would appear to have been the above structures 
 which induced M'Coy to place Lyopora favosa in the genus 
 Heliolites (Palceopora) ; but microscopic sections prove, beyond 
 the shadow of a doubt, that they are certainly not " ccenen- 
 chymal " in their nature. They are either placed at the angles 
 of junction of the original corallites (when these can be detected 
 at all), or they run in the substance of the wall itself. It is 
 clear, therefore, that they cannot be " ccenenchymal tubules ; " 
 but it is at the same time difficult to say precisely what they 
 are. Probably they are (as suggested by Mr R. Etheridge, 
 jun., and myself, loc. cit., p. 28) mere vacuities due to imperfect 
 deposition of sclerenchyma ; but the more regularly-shaped 
 ones are possibly of the nature of the " intramural canals" of 
 Columnopora, whatever these may be. 
 
 As regards the other features in the anatomy of Lyopora, I 
 have failed to find any evidence of the existence of " mural 
 pores," after a careful examination of a large number of speci- 
 mens and of microscopic sections. I am not, however, prepared 
 to assert that mural pores may not ultimately be proved to 
 be present. The septa are entirely rudimentary, and have the 
 form of broad, obtuse, and somewhat irregular marginal ridges, 
 which project to an extremely limited extent into the visceral 
 chamber (PI. IX., fig. 2). The tabulae are strong and complete, 
 and, in the only species known, are usually remote and hori- 
 zontal (PI. IX., fig. 2 a). 
 
COL UMNARIAD^E. 1 89 
 
 The apparent absence of mural pores renders it impossible to 
 refer Lyopora to the Favositida ; and the undoubted absence 
 of " ccenenchymal tubules " entirely precludes any comparison 
 between it and the Helioporida. Under these circumstances 
 it is very difficult to state anything definite as to the systematic 
 place which the genus ought to occupy. Its general characters 
 are in many respects such as to approximate it to Columnaria, 
 Goldfuss, which will be discussed immediately ; but this can 
 hardly be said to make matters any clearer, for the precise 
 zoological relationships of the latter are still very uncertain. 
 Moreover, a close comparison of specimens and thin sections of 
 these two genera has convinced me that the points of resem- 
 blance between them are largely counterbalanced by points of 
 structural dissimilarity. Thus the typical forms of Columnaria 
 not only want the extraordinarily thickened walls of Lyopora, 
 but possess a septal system, which, even in its most rudimentary 
 condition, is a marked advance upon that of the latter ; while 
 the amalgamation of the walls of the corallites is never carried 
 to the extent of in any way obliterating or obscuring the line of 
 demarcation between contiguous tubes. The typical species of 
 Columnaria, indeed, present many features which would induce 
 us to place them among the Rugose Corals, whereas Lyopora 
 exhibits no characters save such as were supposed to be dis- 
 tinctive of the old group of the " Tabulata." Upon the whole, 
 therefore, I must at present leave the position and zoological 
 relationships of Lyopora entirely open questions. 
 
 So far as known, the geological range of the genus Lyo- 
 pora is an extremely limited one, the only recorded species 
 being the L.favosa, M'Coy, sp., of the Lower Silurian rocks of 
 Ayrshire. I subjoin a brief diagnosis of this singular species, 
 extracted from the ' Monograph on the Silurian Fossils of 
 Girvan,' by Mr R. Etheridge, jun., and myself. 
 
1 90 TABULATE CORALS. 
 
 Lyopora favosa, M'Coy, sp. 
 (PI. VIII., figs. 3, 3 a, and PL IX., figs. 2, 2 a.) 
 
 Palaopora (?) favosa, M'Coy, Ann. and Mag. Nat. Hist, ser. 2, vol. vi. p. 
 
 285, 1850. 
 
 ,, favosa, M'Coy, Brit. Pal. Foss., p. 15, PL I. c, fig. B, 1851. 
 Heliolites (Palaopora) favosus, Salter, Quart. Journ. Geol. Soc., vol. vii. p. 
 
 170, 1851. 
 Lyopora favosa, Nicholson and R. Etheridge, jun., Mon. Sil. Foss. Girvan, p. 
 
 26, PL II., figs, i-ie, 1878. 
 
 Spec. Char. Corallum composite, massive, spheroidal, hemi- 
 spherical, pyriform, or irregular in shape ; the corallites sub- 
 cylindrical, elliptical, hexagonal, or irregular in outline, firmly 
 united with one another. Calices usually circular or hexagonal, 
 averaging a line and a half in diameter, the lip coarsely granu- 
 lar. Walls imperforate, extraordinarily thick, the interspaces 
 between any two contiguous tubes being occupied by dense 
 calcareous tissue, of from three-quarters of a line to more 
 than a line in thickness, sometimes with minute and irregu- 
 lar vacuities. Septa rudimentary, often wanting in individual 
 calices, 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. Having discussed the characters of the genus Lyopora, 
 of which this is the only recorded species, at some length, it is 
 unnecessary to dilate upon the above specific diagnosis. The 
 reference of this curious form by Milne-Edwards and Jules 
 Haime to Heliolites inter stinctus, Wahl. (Brit. Foss. Corals, p. 
 250), has been shown by Mr R. Etheridge, jun., and myself 
 (loc. cit. supra), to have been caused by the erroneous figures 
 given by M'Coy of its internal structure. The form of the 
 corallum is very variable, but it was rooted at its base to some 
 foreign body, and the diverging corallites seem to have opened 
 over the whole of the free surface, no traces of an epitheca 
 
COL UMNARIAD^E. 1 9 1 
 
 having come under my observation. The size of ordinary 
 specimens varies from an inch or less in height and breadth up 
 to half a foot or more. 
 
 Formation and Locality. Abundant in the Lower Silurian 
 Limestone of Craighead, Girvan, Ayrshire. 
 
 Genus. COLUMNARIA, Goldfuss, 1826. 
 (Petref. Germ., t. i. p. 72.) 
 
 Columnaria (pars), Goldfuss, Petref. Germ., t. i. p. 72, 1826. 
 Favistella?- Hall, Pal. N.Y., vol. i. p. 275, 1847. 
 Favistella, Nicholson, Sec. Rep. Pal. Ont., p. 21, 1875. 
 
 Gen. Char. Corallum composite, massive, composed of poly- 
 gonal, closely-compacted and contiguous corallites, which are 
 united by their walls, but do not possess mural pores. Walls 
 of the corallites not excessively thickened. Septa well devel- 
 oped, typically extending nearly to the centre of the visceral 
 chamber, and alternately large and small. Tabulae extremely 
 well developed, complete, and horizontal. No columella or 
 ccenenchyma. 
 
 Obs. This genus was founded by Goldfuss to include certain 
 massive aggregate corals, which closely resemble Favosites in 
 general appearance, but differ in having lamellar septa and im- 
 perforate walls. Of the three forms included by Goldfuss under 
 this name, two appear to be compound Rugose corals, as shown 
 by Milne-Edwards and Haime (Pol. Foss. des Terr. Pal., p. 
 308, 1851); and the title Columnaria can therefore only be 
 retained for the third of these viz., C. alveolata, which occupies 
 the first place in the original description, and must therefore 
 be strictly regarded as the type-species. Nor can any doubt be 
 
 1 The name of Favistella was proposed in 1846 (U.S. Expl. Exped. Zooph., p. 
 538) by Dana for "a part of the true Favosites, in which the cells are stellate with 
 twelve distinct rays." There is, however, no sufficient evidence that Dana had in 
 view the true Columnarice, rather than the similar-looking forms of Favosites with 
 well-developed septa ; and it is quite clear that Hall introduced the name Favistella 
 quite independently. 
 
1 92 TABULATE CORALS. 
 
 entertained as to the identity of the coral which Goldfuss de- 
 scribed and figured under the name of C. alveolata, with that of 
 the coral subsequently described and figured by Hall under the 
 designation of Favistella stellata (Pal. N.Y., vol. i. p. 275, PI. 
 LXXV., fig. i). Indeed, the original specimens described by 
 Goldfuss were derived from North America. 
 
 It is certain, then, that the genus Columnaria, if kept at all, 
 can only be retained for corals having the characters of C. alveo- 
 lata, Goldf. ( = Favistella stellata, Hall); and there is also no 
 doubt that the strict law of priority demands that this course 
 should be followed, and that the ill-characterised genus of Gold- 
 fuss should take precedence over the properly-defined Favistella 
 of Hall. I have elsewhere pointed out (Sec. Rep. Pal. Ont, p. 
 21) that this course is attended with grave inconvenience, in 
 consequence of the fact that the name of Columnaria alveolata 
 has been used generally, as by Hall, Billings, and others, for 
 an entirely different species to that so designated by Goldfuss. 
 In deference, however, to the opinion of authorities whom 
 I respect, I shall consider Favistella, Hall, as a synonym of 
 Columnaria, and I shall subsequently discuss the characters of 
 the coral which has been generally, but erroneously, described 
 as Columnaria alveolata, Goldf. 
 
 Taking, then, the true C. alveolata of Goldfuss (the Favistella 
 stellata of American palaeontologists) as the type of the genus 
 Columnaria, we find that the genus includes massive corals, 
 of a hemispheric, pyriform, or irregularly spheroidal shape, and 
 often of large size, composed of prismatic or polygonal coral- 
 lites, which radiate outwards from the base of attachment. The 
 walls of the corallites are not excessively thickened, and con- 
 tiguous tubes are usually in contact throughout their entire 
 length. An occasional and partial separation of the corallites 
 close to their mouths can, however, be sometimes observed ; 
 and in an allied species (C. calicina, Nich.) the tubes become 
 to a large extent disjunct, though never wholly so, in the upper 
 portion of the corallum. The boundary-lines between contigu- 
 ous corallites are never completely obliterated (PI. X., figs, i 
 
COL UMNARIAD^E. 1 93 
 
 and 2), and weathered or roughly-fractured surfaces sometimes 
 exhibit the exterior of the tubes. No evidence has been ob- 
 tained by thin sections, or otherwise, as to the existence of 
 "mural pores," and it must therefore be presumed that the 
 walls are imperforate. 
 
 The septa (PI. X., figs, i and 2) are well developed and 
 lamellar, extending from the top to the bottom of the visceral 
 chamber, and reaching more or less nearly to the centre of the 
 tube, which they do not quite reach. There is sometimes a 
 curious irregularity of the septa, one or more being predomi- 
 nantly developed, and there are also two distinct sets of these 
 structures, a long and a short series, alternating regularly with 
 one another. Lastly, the tabulae are very numerous and well 
 developed, being complete and more or less horizontal, and not 
 placed at corresponding levels in contiguous tubes. 
 
 The affinities of the genus Columnaria are still very obscure. 
 If a more extended examination of specimens by means of thin 
 sections, with special reference to this point, should show the 
 walls to be really imperforate, as we must at present conclude 
 them to be, and as they probably really are, then we cannot 
 place the genus in the Favositidce. Nor is there any other 
 group among the old "Tabulate Corals" of Milne-Edwards 
 and Haime to which they could be referred with any greater 
 propriety. The genus, indeed, is much more like one of the 
 Rugosa than one of the " Tabulata." It possesses well- 
 developed and lamellar septa (in its type-forms at any rate), 
 and its tabulae are hardly better developed than in several 
 undoubted Rugose corals (such as Amplexus, Diphyphyllum, 
 &c.) In fact, it might be at once, and without any violence, 
 placed in the Stauridce, close to Stauria, except that there is no 
 predominant development of four of the septa. On the other 
 hand, the genus has many points of likeness with Lyopora, 
 which has no Rugose affinities to speak of. Upon the whole, 
 therefore, it seems impossible at present to assign any definite 
 systematic place to Columnaria, and we must regard it as the 
 
 N 
 
194 TABULATE CORALS. 
 
 type of a special family, to which the name of Columnariadce 
 may be applied. 
 
 Professor Verrill (Amer. Journ. Sci. and Arts, ser. 3, vol. iii. 
 p. 191, 1872) has drawn attention to the resemblance between 
 Columnaria and certain of the Astraeans (such as Ccelastrced), 
 and he has expressed the opinion that the genus, " if not actu- 
 ally a member of the Astrceidce, should at least be referred to 
 a family very near that group." There is much to be said for 
 this view, but considering the less regular development of the 
 septal apparatus in Columnaria, and its apparent want of any 
 endothecal dissepiments (apart from the " tabulae," if these 
 structures are regarded as dissepimental), I think it safer in 
 the meanwhile to leave the position of the genus an open 
 question. 
 
 The typical species of the genus Columnaria are C. alveolata, 
 Gold, (non M'Coy and Hall), C. Gothlandica, E. and H., and 
 C. calicina, Nich., all of which are Silurian in their distribution. 
 The first and last of these are principally Lower Silurian, and 
 the Upper Silurian C. Gothlandica, E. and H. (Pol. Foss. des 
 Terr. Pal., p. 309, PI. XIV., figs. 2 and 2 a), would appear to 
 be hardly separable specifically from C. alveolata, Goldf. 
 
 There remains the Silurian coral which has been described 
 by Hall, M'Coy, and other observers under the name of Colum- 
 naria alveolata, Goldf., with which we may possibly associate 
 certain other forms (e.g., C. erratica, Billings). This form I 
 shall briefly consider under the name of Columnaria (?) Halli, 
 mihi, though I very greatly doubt if it be really referable to the 
 genus Columnaria of Goldfuss. As to the other forms which 
 have been included by various writers under the genus Colum- 
 naria, I can say nothing, as I have not had the opportunity of 
 examining actual specimens. 
 
COL UMNARIAD^E. ! 95 
 
 Columnaria alveolata, Goldfuss. 
 (PI. X, figs, i, i a.) 
 
 Columnaria alveolata, Goldfuss, Petref. Germ., t. i. p. 72, PI. XXIV., fig. 7, 
 
 1826. 
 multiradiata, Castelnau, Sil. Syst. de 1'Ame'r. sept., p. 44, PI. 
 
 XIX., fig. i, 1843. 
 Favistella stellata, Hall, Pal. N.Y., vol. i. p. 275, PL LXXV., fig. i, 1847. 
 
 (Non Columnaria alveolata. Hall, ibid., p. 47.) 
 Columnaria alveolata (pars), Milne-Edwards and Haime, Pol. Foss. des Terr. 
 
 Pal., p. 309, 1851. 
 ,, GotMandica, Milne-Edwards and Haime, ibid., p. 309, PI. XIV., 
 
 figs. 2, 2 a, 1851. 
 Favistella stellata, Nicholson, Sec. Rep. Pal. Ont., p. 23, 1875, and P^- Ohio, 
 
 vol. ii. p. 185, 1875. 
 Columnaria stellata, Rominger, Foss. Cor. of Michigan, p. 90, PI. XXXIV., 
 
 fig. 3, and PI. XXVIII., fig. i, 1876. (Non Columnaria 
 
 alveolata, M'Coy, Hall, Billings, Rominger, &c.) 
 
 Spec. Char. Corallum massive, subhemispheric, or pyriform, 
 often attaining a very considerable size. Corallites prismatic, 
 hexagonal or pentagonal, but often more or less drawn out 
 along one axis, the larger ones being from rather less than two 
 to over three lines in their long diameter, and having numerous 
 much smaller tubes interspersed amongst them. Walls of the 
 corallites more or less amalgamated, the line of division between 
 contiguous tubes still remaining quite distinct. Mural pores 
 apparently wanting. Septa unequally developed, alternately 
 large and small, the latter quite rudimentary, and the former 
 extending usually across two-thirds of the distance between the 
 wall and the axis of the visceral chamber, or even reaching the 
 last-mentioned point. The septa are thin and flexuous but 
 completely lamellar, and the number of each series varies from 
 about twelve to fifteen or more. Tabulae complete, horizontal, or 
 somewhat flexuous, about six in the space of two lines. Calices 
 polygonal, unequally- sized, moderately deep, with thin margins, 
 usually closely contiguous, but sometimes separated by slight 
 interspaces ; the floor formed by the uppermost tabula, the 
 surface of which is striated by the radiating septa. 
 
196 TABULATE CORALS. 
 
 Obs. Having given an account of this species in describing 
 the structure of the genus Columnaria, I have little to add to 
 the above specific diagnosis. I entertain no doubt at all that 
 the specimens described and figured by Goldfuss (Petref. Germ., 
 PI. XXIV., fig. 7) are really the present form so well known 
 to American palaeontologists under the name of Favistella stel- 
 lata, Hall and that they are quite different to the species 
 described by Hall, M'Coy, and others under the name of C, 
 alveolata. Not only do Goldfuss's figures show the extension 
 of the septa to near the axis of the visceral chamber in the 
 clearest possible manner, but his examples were actually col- 
 lected on the shores of Seneca Lake, in the State of New 
 York, where the Lower Silurian Rocks do not occur in place, 
 so that they were doubtless derived from a travelled boulder 
 originally belonging to the Hudson River formation. 
 
 I should be inclined to think that a re-examination of the 
 specimens upon which Mr Billings founded his Columnaria 
 rigida (Geol. Surv. of Canada, Rep. of Prog, for 1857, p. 167, 
 1858) would show that these are really the same as C. alveola fa. 
 Mr Billings himself states that the principal distinction between 
 the two is, that in C. rigida the septa do not quite reach the 
 centre of the visceral chamber, whereas in C. alveolata (which 
 he calls Favistella stellata, Hall) the septa not only reach the 
 centre, but are often " so strongly developed there as to pro- 
 duce by their junction the appearance of a pseudo-columella." 
 This last-mentioned appearance is one that I have never seen, 
 while it is quite common for the septa of C. alveolata to fall 
 short of the centre of the visceral chamber, as indeed the 
 most of them almost always do ; so that I hardly think C. 
 rigida, Bill., can be retained as a distinct species. 
 
 Formation and Locality. Abundant in the Cincinnati group 
 (Hudson River Group) of Canada and the United States. Dr 
 Rominger (Foss. Cor. of Michigan, p. 90) quotes it also from 
 the Niagara Group (Upper Silurian). 
 
COL UMNARIAD^E. 197 
 
 Columnaria calicina, Nicholson. 
 (PI. X., figs. 2, 2 a.) 
 
 Favistella calicina, Nicholson, Rep. Brit. Ass., 1874, and Second Rep. Pal. 
 
 Out., p. 24, fig. 9, 1875. 
 Columnaria Hertzeri, Rominger, Foss. Cor. of Michigan, p. 90, 1876. 
 
 Spec. Char. Corallum subhemispheric or pyriform, of 
 moderate but not very large dimensions. Corallites partially 
 in contact and partially more or less completely separate from 
 one another, averaging about two lines in diameter, but vary- 
 ing from less than a line up to three lines. Where the coral- 
 lites are more or less uniformly contiguous (as always towards 
 the base of the colony), they are prismatic or polygonal. In 
 diverging from the base, however, the tubes separate from one 
 another to a greater or less extent, so as to leave more or less 
 conspicuous intervals between them. In these portions of their 
 course each corallite is surrounded by a distinct and separate 
 wall, which is marked exteriorly by strong vertical ridges and 
 intervening grooves, about five of which occupy the space of 
 one line, together with fine encircling striae. Septa alternately 
 large and small, twenty-eight in number altogether, the prim- 
 ary ones being continued over the upper surfaces of the tabulae 
 to near the centre of the corallites, whilst the secondary ones 
 are marginal and rudimentary. Tabulae well developed and 
 complete, about three in the space of one line. Increase by 
 calicular gemmation, combined with parietal budding. 
 
 Obs. This pretty little species is very distinct from C. alveo- 
 lata, Goldf., from which it may be readily separated by the 
 following characters : i. It is much more diminutive in aver- 
 age size than C. alveolata, its colonies rarely exceeding three 
 inches in diameter and two inches in height, and being often 
 much smaller than this. 2. The corallites are comparatively 
 lax and discrete in their mode of growth. Rarely they may 
 be more or less contiguous and prismatic in form throughout 
 the greater part of their course. More usually, they are cylin- 
 
TABULATE CORALS. 
 
 drical or subcylindrical, and as they radiate from the base, 
 become more or less widely separated towards their termina- 
 tions. Hence the surface of a mass of C. calicina (fig. 28) 
 
 Fig. 28. I a, A colony of Columnaria calicina, Nich., from the Hudson River Group of 
 Canada, of the natural size ; I l>, A single calice of the same enlarged ; 2, A calice of 
 Columnaria (?) ffalli, Nich., (C. alveolata, auctt. non Goldf.), enlarged. 
 
 often presents an appearance similar to the convolutions of 
 the human cerebrum or to a colony of Fascicularia. 3. It is 
 only where the corallites are in actual contact that their walls 
 are united, and in the remaining portions of their course each 
 is enclosed in a distinct and separate wall, marked with con- 
 spicuous vertical ridges and fine encircling striae. 4. The 
 increase of the corallum is effected by calicular gemmation, 
 and apparently also to some extent by lateral budding, the 
 former mode of growth not seeming to occur in C. alveolata. 
 When we come to consider the internal structure of C. 
 calicina, we find that the differences which separate it from 
 C. alveolata, Goldf., depend principally upon the peculiar 
 mode of growth of the former, the anatomical characters of 
 the two species being very much the same. Transverse 
 sections (PI. X., fig. 2 d) show that though the tubes in the 
 contiguous portions of their course are practically amalgamated 
 by their walls, the real duplicity of their walls is never lost, the 
 actual line of division between neighbouring corallites being 
 still conspicuously recognisable under the microscope. In this 
 respect, therefore, C. calicina entirely agrees with C. alveolata. 
 These sections, further, show a highly " Rugose " condition of 
 
COL UMNARIAD^E. x 99 
 
 the septa, these structures being divisible into a double series 
 of alternately long and short septa, of which the latter are quite 
 rudimentary and marginal, while the former vary greatly in their 
 development. Sometimes they fall short of the centre by a con- 
 siderable interval as is also usually the case in C. alveolata 
 but in other tubes they nearly or quite reach the axis of 
 the visceral chamber. Moreover, the phenomena which the 
 septa exhibit are precisely such as every student of the Rugose 
 corals is familiar with. The longer septa, namely, are not of 
 uniform length, but exhibit clear differences in their develop- 
 ment, almost amounting to that produced by the existence of 
 regular " cycles." Some of them quite reach the centre, others 
 fall a little short of it ; and there is even a tendency to the pro- 
 duction of a single predominant septum, or of two such, towards 
 the sides of which the remaining septa bend. Lastly, it is quite 
 common for the longer septa to be more or less united with one 
 another by their inner ends in a series of fascicles, though at 
 other times each may be quite free. 
 
 Vertical sections of the corallum show no features of special 
 structural importance (PI. X., fig. 2 a). When they pass accu- 
 rately through the centre of the visceral chamber, the princi- 
 pal or only structures observable are the tabulae, which are com- 
 plete, essentially horizontal, though flexuous, and about six in 
 number in the space of two lines. On the other hand, when 
 the section passes at all out of the central line of the tubes, the 
 tabulae are cancellated by vertical lines representing the cut 
 edges of the septa. No mural pores have been detected. 
 
 Formation and Locality. Abundant in the Cincinnati Group 
 (Hudson River formation) of the Credit River, Ontario. Dr 
 Rominger quotes the same species (under the name of C. 
 Hcrtzeri, Rom.) from the Cincinnati Formation of Kentucky. 
 
200 TABULATE CORALS. 
 
 Columnaria (?) Halli, Nicholson. 
 (PL X., figs. 3, 3 a.) 
 
 Columnaria alveolata, Hall, Pal. N.Y., vol. i. p. 47, PL XII., figs, i a - c. 
 
 alveolata, Billings, Geol. Can., fig. 70, p. 139, 1863. 
 
 alveolata, Nicholson, Sec. Rep. Pal. Ont., p. 8, 1875. 
 
 alveolata, Rominger, Foss. Cor. of Michigan, p. 89, PL XXXIV., 
 
 figs, i, 2, and 4, 1876. 
 (Non Columnaria alveolata, Goldfuss.) 
 
 Spec. Char. Corallum forming large massive colonies, which 
 vary from a few inches to several feet in diameter, and which 
 are composed of variously- sized polygonal corallites, in close 
 contact with one another throughout their entire length. The 
 walls of the corallites are not excessively thickened, and they 
 are so completely amalgamated in contiguous tubes that even 
 under the microscope the original line of demarcation between 
 the tubes can be made out with difficulty or not at all. The 
 large tubes are usually from two to three lines in diameter, 
 though occasionally considerably more than this ; and the 
 smaller corallites are of all sizes. Septa marginal, in the 
 form of obtuse longitudinal ridges, which vary in number 
 from twenty to forty, do not extend to any distance into 
 the visceral chamber, and are not divisible into an alternat- 
 ing longer and shorter series. Tabulae strong, horizontal, 
 and complete, about half a line apart or sometimes closer. 
 Mural pores not recognised with certainty. 
 
 Obs. I have come to the conclusion, after full consideration, 
 that the best course to adopt with regard to this species is to 
 give it a distinct specific name, though it has so long been 
 known to palaeontologists as C. alveolata, Goldf., that this 
 course is attended with much inconvenience, and I have 
 myself elsewhere opposed it (Sec. Rep. Pal. Ont, p. 8). 
 Dr Rominger has evaded the difficulty, as I tried to do, 
 by reserving the name of C. alveolata for the form now 
 under consideration, and by retaining Hall's Favistella stel- 
 lata. It is, however, quite certain that the latter is really 
 
COL UMNARIAD^E. 2 o i 
 
 the Columnaria alveolata of Goldfuss, and it is therefore best 
 to give the present species a distinct title rather than to per- 
 petuate a source of endless confusion. I am the more inclined 
 to take this course, as I am disposed to doubt very strongly if 
 the present form can be referred to Columnaria at all, and 
 whether it is not truly a perforate coral, congeneric with 
 Nyctopora, Nich. The material in my hands is, however, 
 not sufficient to settle this point finally. All that I can 
 affirm is that Columnaria (?) Halli agrees with Nyctopora 
 Billingsii, Nich., precisely in its general form and aspect, in 
 the complete amalgamation of the walls of the corallites, and 
 in the fact that the septa have the form of blunt marginal 
 ridges, not divisible into a double series. In all these points 
 C. (?) Halli differs from the true C. alveolata, Goldf., and from 
 the allied C. calicina, Nich. I am disposed also to think that 
 I can detect in thin vertical sections of C. (?) Halli small 
 mural pores, such as are so abundant in Nyctopora Billingsii, 
 On the existence, however, of this crucial character, I must at 
 present speak with much reserve, for the state of preservation 
 of my specimens is such that I have not succeeded in obtaining 
 from them any microscopic sections that could be confidently 
 relied upon as deciding a point of such delicacy and importance. 
 Leaving the existence of mural pores an open question, I 
 have little to add to the 
 above specific diagnosis 
 of C (?) Halli. The gen- 
 eral form of the corallum 
 (fig. 29) is very similar to 
 that of C. alveolata, Goldf., 
 though the colonies most- 
 ly tend to assume a flat- 
 tened and laterally ex- 
 panded form. The COral- Fig. 29. A small colony of Columnaria (?) Halli , 
 .. , , , Nich. . from the Trenton Limestone of Canada, 
 
 llteS are always polygonal O f the natural size. (After Billings.) 
 
 and prismatic, of very un- 
 equal sizes, but invariably in close contact throughout, and with 
 
202 TABULATE CORALS. 
 
 walls of no more than average thickness. Transverse sections 
 (PI. X., fig. 3) show that the walls are so entirely amalgamated 
 in contiguous corallites that it is difficult to detect the original 
 boundaries of the tubes. The same sections show that the 
 septa are in the form of strong vertical ridges, which vary 
 in number in tubes of different dimensions, but are invariably 
 marginal, and never extend beyond a very limited distance into 
 the interior of the visceral chamber. There is also no trace of 
 that division of the septa into an alternately-disposed long and 
 short series, such as has been seen to be so characteristic of 
 C. alveolata, Goldf., and C. calicina^ Nich. 
 
 Vertical sections (PL X., fig. 3 a) exhibit principally the 
 strong, remote, and complete tabulse ; but when the plane of 
 the section comes to coincide more or less closely with the 
 plane of one of the walls of the tube, we observe also a 
 series of vertical ridges or bands, which represent the broad 
 edges of the septa as seen in section. In such parts of vertical 
 sections, I think I can detect, as before said, small mural pores, 
 but I cannot affirm this positively. 
 
 Formation and Locality. Abundant in the Trenton Lime- 
 stone of Canada and the United States. Professor Hall's 
 specimens seem to be exclusively from the Black River 
 Limestone, which forms an inferior division of the Trenton 
 Limestone in the State of New York. It has not hitherto 
 been detected in the Cincinnati formation (Hudson River 
 Group) ; and this of itself is to some extent evidence of its 
 distinctness, considering that Columnaria alveolata, Goldf. 
 (Favistella stellata. Hall), is such a common coral in the 
 latter formation. 
 
203 
 
 CHAPTER VIII. 
 
 SYRINGOPORIDyE. 
 
 IN the family of the SyringoporicUe, as typified by Syringopora 
 itself, there is a fasciculate corallum, commencing in the form of 
 a reticulated tubular expansion, which sends up at intervals 
 vertical, more or less cylindrical corallites, enclosed in strong 
 compact walls. The corallites are either completely free, as 
 regards absolute contact, or only touch each other occasionally 
 at limited points, and their visceral chambers communicate 
 directly by means of hollow connecting-processes, into which 
 the tabulae are prolonged. Delicate spiniform septa are usually 
 present. The tabulae are well developed, more or less funnel- 
 shaped, and often forming an axial tube in the median line of 
 the visceral chamber. 
 
 The type of this family is Syringopora^ Goldf, which was 
 placed by Milne- Edwards and Haime (Brit. Foss. Cor. Intr., p. 
 Ixii, 1850) with Haly sites and Thecostegites in the tribe Haly- 
 sitince of the family ChceteticUe. Subsequently, the same authors, 
 while retaining Syringopora in the same systematic position, 
 associated with it the additional genera Fletcheria, E. and H., 
 and Chonostegites, E. and H. (Pol. Foss. des Terr. Pal., p. 280, 
 1851). The only other genera that subsequent authors have 
 : shown a disposition to associate with Syringopora are Canna- 
 pora, Hall, and Aulopora, Goldf. 
 
 Of the above genera, Halysites, Fischer, is shown conclu- 
 sively, by its minute structure, to have no genuine affinities 
 with Syringopora, and must therefore be retained in the mean- 
 
204 TABULATE CORALS. 
 
 while as the single representative of the family of the Haly- 
 sitidce, while Syringopora must be considered as the type of a 
 new family, for which the name of Syringoporidcz may be ap- 
 propriately chosen. The only other form which can, in the 
 meanwhile, be at all definitely placed in the Syringoporida is 
 Cannapora, Hall. The few specimens which I possess of this 
 singular genus which, so far as is known, is confined to the 
 Upper Silurian deposits of North America are so poorly pre- 
 served that I have been unable to make microscopic sections of 
 them, and can give no details as to their minute internal struc- 
 ture. Dr Rominger (Foss. Cor. of Michigan, p. 85, 1876) has, 
 however, examined good specimens of Cannapora jnnciformis, 
 Hall, the type-species of the genus, and the following generic 
 diagnosis is given by him : 
 
 " Colonies of closely-approximated erect tubules, with stout 
 walls, sprouting from an incrusting basal expansion, formed of 
 prostrate tubules, growing and multiplying in the same manner 
 as an Aulopora. The erect ends of the tubules are annulated 
 by wrinkles of growth and by sharp-edged periodical offsets 
 marking an interruption and renewed growth from the inner 
 circumference of the old orifices. The sides of the tubes are 
 partly connected by horizontal expansions of the walls, partly 
 in direct contiguity, in which latter case the otherwise circular 
 tubes are pressed into a polygonal shape, and connect in the 
 contiguous parts by lateral pores. The orifices are slightly 
 dilated at the margins, radiated by twelve spinulose projections, 
 rows of which extend through the whole length of the tubes. 
 Diaphragms are not often developed, direct, transverse, and not 
 funnel-shaped as in Syringopora" 
 
 From the above description it will be evident that Cannapora 
 supplies us with a very interesting link between Syringopora 
 and Favosites, though upon the whole most closely allied to the 
 former. Cannapora closely resembles Syringopora in its habit 
 and general form, and the periodically-produced horizontal 
 expansions which connect contiguous corallites have been shown 
 by Rominger to be sometimes developed in Syringopora tabii- 
 
SYRINGOPORID^E. 205 
 
 lafa, Van Cleve. The chief distinction between Cannapora and 
 Syringopora would, in fact, seem to consist in the possession 
 by the former of horizontal instead of infundibuliform tabulae. 
 On the other hand, Cannapora, Hall, approaches Favosites in 
 the possession of "mural pores " in those parts of the corallum in 
 which the corallites are in actual contact; and it maybe directly 
 compared with such members of the Favositides as Vermipora, 
 Hall, in which a partially disjunct condition of the tubes exists. 
 
 Chonostegites, E. and H., has been shown (see supra) to be a 
 true member of the Favositidce closely allied to Michelinia, De 
 Kon., and it cannot, therefore, be associated with Syringopora. 
 
 Thecostegites, E. and H., again, is defined as having an in- 
 crusting submassive corallum, composed of short cylindrical 
 corallites, which are united by strong mural expansions in the 
 form of more or less distinct horizontal platforms. The walls 
 of the corallites are well developed, and are only free in the 
 intervals between the periodic expansions just spoken of. The 
 calices are circular ; imperfect septa to the number of twelve 
 are present ; and the tabulse are distinctly horizontal (Pol. Foss. 
 des Terr. Pal., p. 297). The type of this genus is T. Bouchardi, 
 Mich., from the Devonian of Ferques in France; and Milne- 
 Edwards and Haime mention that they have seen specimens 
 from the Falls of the Ohio, and possibly from the Eifel. They 
 further point out that the genus has a decided affinity to Syrin- 
 gopora, and that it has special relations with 5\ tabulata, Van 
 Cleve. They give a short and very insufficient description of 
 a second species (T. auloporoides) from the Devonian of Spain. 
 Recently Dr Rominger (Foss. Cor. of Michigan, p. 83) has 
 made out a strong case in favour of the view that Thecostegites 
 Bouchardi is really nothing more than a peculiar condition of 
 growth of Syringopora tabulata, Van Cleve. Dr Rominger, 
 however, seems to consider that the original specimens of T. 
 Bouchardi were derived from the Falls of the Ohio, which is cer- 
 tainly not the case ; and until these specimens are re-examined, 
 it cannot be said that absolutely final evidence has been brought 
 forward in favour of the complete suppression of Thecostegites. 
 
206 TABULATE CORALS. 
 
 It need only be added that if Thecostegites should prove finally 
 to be nothing more than a mode of growth of Syringopora, 
 then the curious little coral from the Lower Silurian of Ayr- 
 shire described by Mr R. Etheridge, jun., and myself (Mon. 
 Sil. Foss. Girvan, p. 50, 1878), under the name of T. (?) Scoti- 
 cus, will have to be removed from the genus Thecostegites, with 
 which it will have no affinity. The coral in question, however, 
 though resembling the figures given of T. Bouchardi, E. and H., 
 in general appearance, is only known from limited material, and 
 it throws no light on the validity or the reverse of the genus 
 Thecostegites. 
 
 The genus Fletcheria was founded by Milne-Edwards and 
 Haime (Pol. Foss. des Terr. Pal, p. 300) for the single species 
 F. tubifera, of the Upper Silurian of Sweden. The genus is 
 defined as having a corallum composed of cylindrical corallites, 
 which increase by calicular gemmation, and are not united 
 laterally either by transverse connecting-processes or by hori- 
 zontal mural expansions. The walls are strong, with a com- 
 plete epitheca ; the septa are rudimentary ; and the tabulae are 
 highly developed and horizontal. As in the case of Thecoste- 
 gites, it seems impossible to determine finally the true position 
 of Fletcheria without a re-examination of the original specimens, 
 upon which Milne-Edwards and Haime founded the genus. 
 Dr Lindstrom (Ann. and Mag. Nat. Hist, ser. 4, vol. xviii. p. 
 13) says that Fletcheria tubifera, E. and H., "seems to be a 
 Cystiphylloid of very variable characters ; " but I do not know 
 the evidence in support of this view. Dr Rominger is disposed 
 to think that Fletcheria, E. and H., and Cannapora, Hall, may 
 be identical and closely allied ; but there seems little decided 
 ground for accepting this view, or indeed for in any way 
 associating Fletcheria with Syringopora or Cannapora. As 
 just remarked, it appears hopeless to try and settle the affin- 
 ities of the genus without access to the type-specimens ; but 
 judging merely from the description and figures of Fletcheria 
 tubifera given by Milne-Edwards and Haime (loc. citl), I 
 should be rather disposed to think that Fletcheria will be found 
 
SYRINGOPORID^E. 207 
 
 to be a member of the Favositid<z> and that Vermipora, Hall, 
 if not an actual synonym, is most nearly allied to it. The 
 calicinal gemmation of F. tubifera is, however, an almost 
 unique feature. 
 
 Lastly, the genus Aulopora, Goldf., has been by various 
 palaeontologists associated with Syringopora^ or even merged 
 with the latter. This view, for reasons which have been pre- 
 viously stated in brief, and which I shall subsequently discuss 
 at greater length, appears to me to be untenable ; and Aulopora 
 must, with our present knowledge, be regarded as the type of 
 a special group. 
 
 From the above remarks it will be seen that no other forms 
 can in the meanwhile, with any definiteness, be placed in the 
 Syringoporidce, except only Syringopora and Cannapora. It is 
 only in the case of the former of these that I have had the 
 opportunity of making myself thoroughly acquainted with the 
 minute characters of the corallum, and I shall therefore not 
 only take this genus as the type of the group, but I shall defer 
 any remarks as to the affinities of the family till I have given a 
 brief description of the peculiarities in its structure. Both the 
 above genera are strictly Palaeozoic, Cannapora being exclu- 
 sively an Upper Silurian form, and Syringopora being confined 
 to the Upper Silurian, Devonian, and Carboniferous periods. 
 
 Genus SYRINGOPORA, Goldfuss. 
 
 (Petref. Germ., t. i. p. 75, 1826.) 
 Harmodites, Fischer, Notice sur les Tubipores fossiies, p. 19, 1828. 
 
 Gen. Char. Corallum commencing as a prostrate network of 
 tubes, which in process of growth sends up numerous vertical 
 corallites. The corallites are cylindrical, arranged with varying 
 degrees of closeness, and each enclosed in a distinct wall. The 
 visceral cavities of contiguous polypes communicate directly 
 by means of a greater or smaller number of hollow horizontal 
 connecting-processes, which in some cases may be nearly or 
 
208 TABULATE CORALS. 
 
 quite obsolete. Tabulae well developed, usually more or less 
 regularly funnel-shaped, and often giving rise to a more or less 
 continuous tube occupying the axis of the visceral chamber. 
 Septa usually slightly developed, spiniform, never lamellar. 
 
 Obs. Few genera of Palaeozoic corals are more clearly 
 marked out than Syringopora by the general form and mode 
 of growth of the corallum. The corallum commences as a 
 stoloniferous prostrate network of anastomosing tubes, which 
 closely resemble an Aulopora in general appearance, and have 
 given rise to the opinion that Aidopora is founded simply upon 
 young colonies of Syringopora. The chief grounds for rejecting 
 this view will be briefly discussed hereafter, but there is one 
 consideration to which attention may here be drawn. The 
 prostrate network which forms the base of a colony of Syringo- 
 pora can be admirably studied in forms like S. fascicularis , 
 Linn., of the Upper Silurian ; and in these cases we find that 
 there is presented to our observation the under surface of the 
 basal reticulation, as figured by Edwards and Haime in the 
 British Fossil Corals, PI. LXV., fig. i c. Now this under 
 surface of the network would, if the coral were an Aulopora, 
 be cemented firmly to some foreign object throughout the 
 whole of its extent, and it would not therefore be exposed to 
 view at all. On the other hand, there is the clearest possible 
 evidence that the basal reticulation of Syringopora was not 
 parasitic at all, and that its under surface was quite free as a 
 general rule, except at one or more circumscribed points 'of 
 attachment. Whether or not the upper surface of the basal 
 reticulation of a Syringopora, prior to the formation of the 
 ascending corallines, has ever been so much as actually observed, 
 is a matter quite open to question. Cases in which the upper 
 surface of such a reticulation have been described or figured 
 (e.g., by Edwards and Haime, Brit. Foss. Cor., PI. LXV., fig. i) 
 may admit of the explanation that the observer was in reality 
 dealing with the colony of a true Aulopora. It seems, indeed, 
 in the highest degree probable that the formation of the ver- 
 tically ascending corallites is commenced in the very earliest 
 
SYRINGOPORID^E, 209 
 
 stages of the formation of the basal network, in which case 
 there is little likelihood of our ever seeing the upper surface of 
 the latter. Even if this were not the case, and if the basal 
 reticulation were really formed as a whole before the ascending 
 tubes began to be thrown up (as seems to have been generally 
 assumed), it may be stated with confidence that nothing short 
 of a microscopic examination of the internal structure would 
 suffice to show whether any given specimen were a young 
 Syringopora or an adult Aulopora, seeing that the macroscopic 
 characters would in either case be precisely the same. Upon 
 the whole, therefore, I cannot regard it as established that 
 Aulopora is founded upon the early stages of Syringopora ; 
 nor can I accept the view propounded by Dr Lindstrom (Ann. 
 Nat. Hist, ser. 4, vol. xviii. p. 14), that the connecting-tubes 
 which unite the neighbouring corallites of Syringopora are 
 " morphologically nothing but the stolons, no longer creeping 
 or attached, but suspended freely between the corallites." 
 
 In its fully-grown condition, the great bulk of the corallum of 
 Syringopora is composed of essentially cylindrical erect coral- 
 lites, which are placed at variable but slight intervals, and 
 usually diverge more or less markedly as the surface is ap- 
 proached, owing to the intercalation of new tubes. The new 
 corallites are produced either by budding from the sides of the 
 old tubes or as offshoots from the transverse connecting-pro- 
 cesses. The walls of the corallites are thick and compact, 
 surrounded superficially by a delicately-wrinkled epitheca, and 
 sometimes strengthened internally by a secondary deposit of 
 finely-laminated sclerenchyma (often in S. geniculata, Phill.) 
 Whether the corallites are near or comparatively remote from 
 one another, their visceral chambers are placed in direct com- 
 munication by means of hollow, usually cylindrical, horizontal 
 connecting-processes. These connecting-processes (fig. 30, A) 
 are tubular, and the anastomosing lamellse of the tabulae from 
 the visceral cavity are prolonged into them. They are there- 
 fore to be regarded as direct outward prolongations of the vis- 
 ceral chambers of the polypes, and they correspond precisely 
 
 o 
 
2 io TABULATE CORALS. 
 
 with the hollow transverse floors which connect the corallites 
 in Chonostegites Clappi, and into which the subvesicular tabulae 
 are similarly extended. The number of the connecting-pro- 
 cesses in the different species of Syringopora is very variable. 
 Usually they are placed at tolerably distant and to some extent 
 regular intervals ; sometimes they are arranged in whorls (S. 
 verticillata, Goldf.) ; sometimes they are greatly reduced in 
 number (S. serpens, Linn.) ; and sometimes they are given off 
 in verticils at corresponding levels, and coalesce so as to form 
 almost uninterrupted horizontal floors (S. tabulata, Van Cleve). 
 In 5*. nobilis, Bill., and 5. intermedia, Nich., both from the 
 Devonian of North America, the erect tubes throw out lateral 
 buds at short intervals, but the corallites are very rarely con- 
 nected by horizontal processes ; and it is possibly the case that 
 these forms should be regarded as a distinct subgeneric type. 
 Lastly, in the singular 5". laxata, Billings, also from the 
 Devonian of North America, the connecting - processes are 
 totally wanting, and the corallites are for the most part quite 
 free. In places, however, the flexuous and closely-set tubes 
 come into partial contact, and at these points they become 
 coalescent by their walls. That their visceral chambers com- 
 municate directly at these points of partial coalescence, I think 
 hardly doubtful, though the preservation of my specimens will 
 not allow me to verify this conjecture. 
 
 How far the arrangement and form of the connecting-tubes, 
 and the distances by which the various corallites in a colony 
 are separated from one another, can be employed as characters 
 of specific value, remains for future consideration. All- that can 
 safely be said at present is, that too much stress has probably 
 been laid by the older observers upon these characters, and 
 that they must in reality be admitted to enjoy a considerable 
 variability within the limits of the same species, though they 
 exhibit at the same time a certain average condition, which is 
 by no means without its value, in each specific type. 
 
 As regards the internal structure of the corallites of Syringo- 
 pora, we have only to notice the condition of the tabulae and 
 the septa. The tabulae (fig. 30) are typically, if not always, 
 
S YRING OPORID^E. 
 
 211 
 
 more or less conspicuously infundibuliform, and they become 
 connected with one an- 
 other in such a manner as 
 to give rise to a central 
 cylindrical tube, occupy- 
 ing the axis of the vis- 
 ceral chamber. Whether 
 or not this tube is present 
 in all the species of the 
 genus is a point for future 
 determination; but its ex- 
 istence is clearly recog- 
 nised by Goldfuss (Petref. 
 Germ., PI. XXV., figs. 
 6 b, 7 b), and I have re- 
 cognised its existence in 
 all the forms which I have 
 . as yet examined micro- 
 scopically. In its general 
 form and structure it is 
 precisely similar to the 
 axial tube which is form- 
 ed by the tabulae in the 
 corallites of Syringolites, 
 Hinde ; and the continu- 
 ity of its internal cavity 
 seems to be interrupted 
 (as in Syringolites] by the 
 occasional extension of a 
 tabula across it. Some 
 forms of Syringopora are 
 stated to possess horizon- 
 tal tabulae, but the true 
 structure and position of these will require to be more fully 
 worked out before this can be finally admitted. 1 
 
 1 Ludwig (Pal. des Urals, p. 10, 1862) has endeavoured to revive the genus 
 Harmodites, Fisch., as distinct from Syringopora, Goldf., upon the ground that 
 
 Fig. 30. A, Part of a longitudinal section of Sy- 
 ringopora reticulata, Goldf., from the Carbonifer- 
 ous Limestone of Kendal, Westmorland, enlarged 
 five times, showing the spiniform septa and the 
 funnel-shaped tabulae with their central tube. 
 Owing to the flexures of the corallites, the section _ 
 cuts the tubes in different parts, sometimes passing 
 close to the wall and showing the cut ends of the 
 spiniform septa, sometimes passing through the 
 axis of the visceral chamber and bisecting the 
 axial tube, and sometimes cutting the axial tube 
 and its enveloping tabulae in an oblique manner. 
 B, Part of a transverse section of the same speci- 
 men, enlarged five times, showing the spiniform 
 septa, and the cut edges of the tabulae surrounding 
 the central tube. 
 
212 TABULATE CORALS. 
 
 The septa in Syringopora are usually, if not always, detected 
 without difficulty in thin sections, whether vertical or trans- 
 verse ; and their most striking feature is, that they are 
 thoroughly " Favositoid " in character, having the form of 
 slender spinules arranged in vertical rows (fig. 30). They 
 never extend more than a limited distance into the interior 
 of the visceral cavity, and they vary much in length. Not 
 uncommonly, also, the descending tabulae carry on their inner 
 faces slender spines (as in the Favositoid genus Chonostegites, 
 E. and H.), which seem to represent inward prolongations of 
 the septa. They are also variable in number, not unfrequently 
 exceeding twenty in a single cycle. Lastly, they are composed 
 of a sclerenchyma which is conspicuously lighter in tint than 
 that of the walls of the corallites (see PI. X., fig. 5). As the 
 result of this, long sections in parts where they happen to 
 coincide with the wall of a corallite (fig. 30, A) exhibit vertical 
 rows of rounded spaces of lighter colour than the surrounding 
 tissues, these being really the cut ends of the spiniform septa 
 divided near their bases, though they might at first sight be 
 readily mistaken for mural pores. 
 
 With regard to the affinities and zoological position of 
 Syringopora, a consideration of the foregoing account of its 
 minute structure will, I think, render it clear that the genus 
 cannot be referred to the Halysitida, to the Tiibiporidce, or to 
 the Rugosa, one or other of these courses having been gener- 
 ally followed by palaeontologists. From Halysites, the genus 
 Syringopora is fundamentally separated by the general form of 
 the corallum, the entirely different construction of the tabulae, 
 the total absence of a set of small zooids coexisting with one 
 of larger dimensions, and the presence of hollow connecting- 
 processes placing the visceral chambers of contiguous corallites 
 
 some forms from the Carboniferous Limestone of Russia appear to have the funnel- 
 shaped tabulae open inferiorly, whereas they are closed in Syringopora. So far as I 
 understand the ambiguous language which he uses on this point, the differences 
 alluded to by Ludwig are of no moment whatever ; and at any rate, the forms which 
 he describes as Harmodites are shown by his figures to be typical species of 
 Syringopora. 
 
SYRINGOPORID^E. 213 
 
 in direct communication. As to the recent genus Tubipora, it 
 seems unnecessary to enter into any detailed discussion, as the 
 known facts as to the internal structure of Syringopora render 
 any direct affinity between the two genera wholly out of the 
 question. More, on the other hand, may be said for the view 
 so ably advanced by Dr Lindstrom (Ann. and Mag. Nat. Hist, 
 ser. 4, vol. xviii. p. 13), that Syringopora is truly a Rugose 
 Coral, allied to Lithostrotion and Diphyphyllum. Even here, 
 however, I think that the distinguished Scandinavian palaeon- 
 tologist has allowed himself to be misled by resemblances which 
 are truly analogical and not fundamental. I am not prepared 
 to allow that there is any true relation of homology between 
 the hollow connecting -tubes of Syringopora and the also 
 hollow radicular processes or connecting-processes of many 
 Rugose Corals. Dr Lindstrom's argument on this point, if 
 carried to a logical conclusion, would necessitate the removal of 
 unquestionable Favositoid and Perforate Corals (such as Mich- 
 elinia, Nodulipora, &c.) to the Rugosa, since these also pos- 
 sess hollow radiciform prolongations. On the other hand, the 
 totally different nature of the tabulae and septa in Syringopora, 
 as compared with these structures in Lithostrotion and Diphy- 
 phyllum to say nothing of the connecting-tubes of the former 
 entirely forbids, in my opinion, any taxonomic union of forms 
 so diverse. 
 
 For my own part, after a careful study of the minute struc- 
 ture of both groups, I am satisfied that the Syringoporida are 
 properly to be regarded as an aberrant group of the Perforata, 
 having genuine relationships with the Favositidte> though dis- 
 tinct from these. Upon this view, the hollow connecting-tubes 
 of Syringopora are homologically nothing more than " mural 
 pores," as existing in corallites which are not in absolute con- 
 tact. In support of this view, I would simply draw attention 
 to the absolute identity in the internal structure of the connect- 
 ing-tubes of Syringopora and the hollow connecting - floors of 
 Chonostegites. Yet Chonostegites is a true Favositoid, with the 
 closest possible relations to Michelinia, De Kon. ; and wher- 
 
2i 4 TABULATE CORALS. 
 
 ever we find its corallites actually in contact, there we find true 
 " mural pores " developed, of the precise type of these structures 
 in Favosites itself. Nor have I much doubt that at any points 
 in the corallum of a Syringopora at which the corallites come 
 into actual contact, openings in the wall placing the body-cavi- 
 ties of the polypes in direct communication will be found to 
 exist, though I have as yet had no opportunity of verifying this 
 conjecture. Indeed, Rominger states that such a condition of 
 parts actually does exist in Cannapora, Hall, which seems to 
 be a close ally of Syringopora. Lastly, as supporting the 
 relationship between the present genus and the Favositidce, it 
 may be pointed out that the singular funnel-shaped tabulae and 
 axial tube of Syringopora are found to exist in an almost pre- 
 cisely similar form in Syringolites, Hinde, a " Favositoid " 
 genus which possesses prismatic contiguous corallites and seri- 
 ally-placed " mural pores " of a form exactly similar to those of 
 Favosites. 
 
 So far as is known, the genus Syringopora ranges from the 
 Silurian to the Carboniferous inclusive, but it attains its max- 
 imum in Devonian and Carboniferous strata. The species 
 which I have at present been able to examine by means of a 
 proper series of microscopic sections are S. reticulata, Goldf., 
 5". geniculata, Phill., 61 intermedia, Nich., 6". laxata, Bill., 6". 
 fascicularis, Linn., and iS 1 . bifurcata, Lonsd. ; but as I have 
 given a tolerably detailed account of the genus, it will be suffi- 
 cient to add merely very brief descriptions of the specific char- 
 acters and minute structure of the first two of these. 
 
SYRINGOPORID^. 2 1 5 
 
 Syringopora reticulata, Goldfuss. 
 (Fig. 30, and PI. X., fig. 5.) 
 
 Syringopora reticulata, Goldfuss, Petref. Germ., vol. i. p. 76, PI. XXV., fig. 8, 
 
 1826. 
 
 reticulata, Phillips, Geol. of Yorkshire, vol. ii. p. 201, 1836. 
 
 reticulata, Edwards and Haime, Pol. Foss. des Terr. Pal., p. 290, 
 
 1851 ; and Brit. Foss. Corals, p. 162, PL XLVL, figs, i, i a, 
 
 1852. 
 
 reticulata, M'Coy, Pal. Foss., p. 84, 1851. 
 
 reticulata, De Koninck, Nouv. Rech. sur les An. Foss., Part I., 
 
 p. 123, PI. XL, figs. 7-7 b, 1872. 
 
 Spec. Char. Corallum fasciculate, of long cylindrical coral- 
 lites, the usual diameter of which is about one line. The dis- 
 tance at which the corallites stand apart varies very much in 
 different colonies, and even in different parts of the same cor- 
 allum, some tubes being in partial contact, while others may be 
 separated by intervals of two lines or more. Ordinarily they 
 are from half a line to a line apart. The tubes are slightly 
 flexuous, but not abruptly geniculated ; and the irregularly- 
 distributed connecting -tubes are about two lines apart, or 
 rather less than this. Well -developed spiniform septa are 
 present, the wall is not thickened by secondary deposit, and 
 the tabulae are infundibuliform, and give rise to the formation 
 of an axial tube. 
 
 Obs. This is one of the most characteristic of the species of 
 Syringopora in the Carboniferous Limestone of Britain, and 
 the above diagnosis embodies its most noticeable structural 
 features. As regards its internal structure, cross-sections (fig. 
 30, B, and PI. X., fig. 5) show that the walls of the corallites, 
 though of tolerable thickness, have no secondary deposit of 
 sclerenchyma in their interior ; while the spiniform septa are 
 well developed, and are arranged in about twenty or twenty- 
 four rows. The cut edges of the infundibuliform tabulae are 
 exhibited in sections of this kind as so many concentrically- 
 disposed or spirally-arranged lines surrounding the transverse- 
 
216 TABULATE CORALS. 
 
 ly-divided axial tube. In long sections (fig. 30, A) the septa 
 present different appearances in different parts of the slide 
 (precisely as in Favosites), according to the inclination of the 
 plane of the section as regards the axial plane of the corallite. 
 Where the section cuts through the axis of the visceral cham- 
 ber, the septa are only seen as lateral spines directed inwards 
 from the bounding walls of the tube ; where the section is to 
 any extent excentric, the cut ends of the spiniform septa come 
 into view as rows of circular spots ; and where the section 
 coincides with the wall of the corallite, the cut bases of the 
 septa look like rows of light spots in the darker-tinted scleren- 
 chyma which surrounds them (see fig. 30, A). The most strik- 
 ing feature in long sections, however, is that of the infundibuli- 
 form tabulae arranged in a succession of invaginating cones, 
 which give rise centrally to a distinct axial tube. This axial 
 tube seems to be intersected by occasional prolongations of 
 the tabulae inwards ; and owing to the flexuous condition of the 
 tubes, it is never laid open continuously for any distance. On 
 the contrary, any long section, as a rule, cuts the axial tube 
 over and over again with varying degrees of inclination, so 
 that we are presented with repetitions of the obliquely-divided 
 tube, surrounded by the cut edges of the concentrically-dis- 
 posed ensheathing tabulae. Lastly, both long and cross sec- 
 tions show that the connecting-processes afford a direct com- 
 munication between the visceral chambers of contiguous tubes, 
 and that the progressive walling off of the visceral cavities of 
 the polypes by the production of tabulae is accompanied by an 
 extension of these structures into the connecting-processes, as 
 these are successively rendered useless. It only remains to 
 add that Milne-Edwards and Haime speak of this species as 
 being remarkable (Brit. Foss. Cor., p. 163) "for the existence 
 of a delicate transverse lamina which passes through the con- 
 centric infundibula, and is shown by a transverse section of the 
 corallum ; " but I can find no traces of such a structure, and 
 do not feel sure if I rightly understand what structure they 
 refer to. 
 
SYRING OPORID^E. 2 1 7 
 
 Formation and Locality. Abundant in the Carboniferous 
 Limestone of Kendal, Shap, Cross-Fell, Red- Hills, and other 
 localities in Westmorland and Cumberland. 
 
 Syringopora geniculata, Phillips. 
 (PL X., figs. 4- 
 
 Syringopora geniculata, Phillips, Geol. of Yorkshire, vol. ii. p. 201, PL II., 
 
 fig. i, 1836. 
 geniculata, M'Coy, Syn. Carb. Foss. of Ireland, p. 190, 1844; 
 
 and Brit. Pal. Foss., p. 83, 1851. 
 geniculata, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., 
 
 p. 291, 1851 ; and Brit. Foss. Cor., p. 163, PL XLVL, figs. 2, 
 
 2 a, and 4, 1852. 
 geniculata^ De Koninck, Nouv. Rech. sur les An. Foss., PL XI., 
 
 fig. 8, and XII., fig. 2, 1872. 
 
 Spec. Char. Corallum fasciculate, of long, diverging, close- 
 set, cylindrical, thick-walled tubes, which are enclosed in a 
 thick wrinkled epitheca, and are usually rather less than one 
 line in diameter. Connecting-tubes numerous, having no reg- 
 ular distribution, and usually placed at distances apart of one 
 line or less, though sometimes more remote. Wall often 
 thickened by a dense laminated secondary deposit of scler- 
 enchyma. Septa short and spiniform. Tabulae numerous, 
 infundibuliform, and giving rise to an axial tube. Distance 
 between the corallites variable, but mostly half a line or less. 
 
 Obs. This species is commonly associated with the preced- 
 ing in the Carboniferous Limestone, and is usually easily to be 
 distinguished from it by the more marked divergence of the 
 corallites from the base of the colony, their closer approxima- 
 tion to one another, their more conspicuously round tubes, their 
 thicker walls, and the greater abundance of the connecting- 
 processes, together with the rather smaller diameter of the 
 corallites. The specific name would indicate that the tubes 
 were markedly geniculate ; but this is by no means the case, 
 and the corallites resemble those of S. reticulata, Goldf., in 
 being simply flexuous. In all the principal features of its 
 
2 j8 TABULATE CORALS. 
 
 internal structure, S. geniculata, Phill., agrees entirely with 
 S. reticulata, and it is unnecessary to dwell upon the pheno- 
 mena exhibited by thin sections. There is, however, one 
 curious character, of very common though apparently not uni- 
 versal occurrence, in which S. geniculata is quite peculiar. One 
 of the most striking features, namely, in S. geniculata, is the 
 apparent thickness of the walls of the tubes ; and thin trans- 
 verse sections show that this is really due to the fact that the 
 proper wall is liable to become lined by a dense, finely-lamin- 
 ated secondary deposit of sclerenchyma (see PI. X., figs. 4 a 
 and 4 b). This secondary deposit is of a markedly darker 
 colour than the true wall, which, along with the short spini- 
 form septa, can be thus easily recognised. In this peculiarity, 
 S. geniculata, Phill., bears to the ordinary forms of Syringopora 
 the same relation that Pachypora and its allies bear to Favosites. 
 This same thickening can often be recognised in long sections 
 (PI. X., fig. 4), but I have not been able invariably to recognise 
 its existence, and I am disposed to think that it is probably 
 present only in certain parts of the tubes (as is the case in 
 Pachypora and in some related forms), or that it depends 
 upon age. 
 
 Formation and Locality. Common in the Carboniferous 
 Limestone of Shap, Kendal, Asby, Ravenstonedale, and other 
 localities in Westmorland. 
 
219 
 
 CHAPTER IX. 
 
 AULOPORID^:. 
 
 THIS family can only be treated very briefly, partly because the 
 materials at present in my possession are insufficient for its 
 complete elucidation, partly because these materials have not 
 yet been fully examined, and partly because the small size and 
 parasitic habit of the type-forms give rise to special difficulties 
 in the way of their satisfactory examination by means of thin 
 sections. The genus Aulopora, Goldfuss, with its ally Clado- 
 cJionus, M'Coy (= Pyrgia, E. and H.), was originally referred 
 by Edwards and Haime to a special division of Zoantharia, to 
 which the name of Z. Tubulosa was given. This division was 
 stated to be characterised (Pol. Foss. des Terr. Pal., p. 310, 
 1851) by the fact that the corallites are pyriform and destitute 
 of " tabulae," and the septa are represented only by vertical 
 striae, while the walls of the thecae are wholly imperforate ; but 
 the undoubted presence of tabulae in typical forms of Aulopora 
 removes the only ground for the retention of the Tubulosa as 
 a distinct division of Zoantharia. The corallum in Aulopora 
 (fig. 31, D) has the form of a creeping, branched or reticulate, 
 system of tubes, attached by the whole of the lower surface 
 to the exterior of a shell, coral, or other foreign body. The 
 basal and prostrate stolons send up tubular or trumpet-shaped 
 corallites at longer or shorter intervals ; but though the ter- 
 minal portions of these are free, the length of the tubes is al- 
 ways very limited, and the reclined corallites never grow up 
 into a fasciculate mass. The walls of the corallites are quite 
 
22O 
 
 TABULATE CORALS. 
 
 compact, and the tubes are for the most part not in contact 
 with one another in any part of their extent. In cases, how- 
 ever, where the tubes come into contact to any extent, it may 
 
 Fig. 21. A, Two examples of Cladochonus Michelini, E. and H., from the Lower Carbonif- 
 erous of Dunbar, of the natural size ; B, A small example of the same, enlarged five times ; 
 C, A longitudinal section of the same species, enlarged five times ; D, Portion of a colony 
 of Aulopora, sp., from the Devonian (Hamilton Group) of Ontario, of the natural size ; 
 E, Longitudinal section of part of the same, enlarged five times ; F, Cross-section of a 
 corallite of the same, enlarged five times, showing the tabulse ; G, Portion of a colony of 
 Aulopora repens, E. and H., from the Devonian of the Eifel, of the natural size; H, 
 Longitudinal section of part of the same, enlarged seven times, showing curved tabulse. 
 
 not impossibly be found that " mural pores " exist at the points 
 of union. The septa are always quite rudimentary, in the form 
 of marginal striae or vertical rows of tubercles. Lastly, the 
 continuity of the visceral chamber is interfered with (in certain 
 species at any rate) by complete transverse tabulae (fig. 31, E, F, 
 and H), which are usually more or less curved, or even funnel- 
 shaped, but which do not appear to give rise to anything 
 resembling the axial tube of Syringopora. 
 
 The resemblance between the colonies of Aulopora and the 
 basal portions of a Syringopora, as regards general aspect, has 
 been already pointed out ; but there is, nevertheless, no suffi- 
 cient reason, in my opinion, for uniting the two. The reasons 
 for this belief have been already given, but may be briefly sum- 
 
AULOPORID^E. 221 
 
 marised as follows: i. The colonies of Aulopora are parasi- 
 tic, the whole of their lower surface being attached to foreign 
 bodies ; whereas the similar-looking basal reticulation of Sy- 
 ringopora was clearly attached only at one or two limited 
 points, the greater part of its under surface being free. 2. 
 The curved and reclined corallites of Aulopora are free only at 
 their terminations, and they do not give origin to erect branches ; 
 whereas the basal network of Syringopora throws up numerous 
 erect corallites from its upper surface, and it has not been shown 
 that the network has any existence apart from the erect tubes 
 to which it gives origin. 3. The connecting - tubes of Sy- 
 ringopora are not known to be represented by any correspond- 
 ing structures in Aulopora. 4. The tabulae of Aulopora are 
 simply curved, or, if infundibuliform, do not appear to give rise 
 to any structure comparable with the axial tube of Syringopora. 
 5. Species of Syringopora abound in formations where the 
 genus Aulopora is hardly or not at all represented, while 
 colonies of the latter are common in deposits in which 
 Syringopora are nearly or quite unknown. 
 
 For the above reasons, I am at present unable to accept the 
 union of Aulopora with Syringopora^ as advocated by some high 
 authorities. At the same time, there are one or two species 
 now referred to Syringopora (such as S. serfiens, Linn., of the 
 Upper Silurian) which have marked " Auloporoid" characters, 
 and which may prove on minute examination to be really 
 referable to the Auloporidcz. 
 
 To Romingeria, Nich. ( = Quenstedtia, Rom.), the present 
 genus bears considerable external resemblance ; and if Rom- 
 inger is right in regarding Aulopora cornuta, Bill., as only the 
 young of Romingeria, this resemblance would seem to be based 
 upon real affinity. As far as our present knowledge goes, how- 
 ever, we are constrained to separate Romingeria from the 
 Auloporidce, as it possesses "mural pores" in parts, while it 
 further differs from Aulopora proper in having an erect 
 
 corallum. 
 
 'x. 
 
 As regards its geological range, the genus Aulopora seems 
 
222 TABULATE CORALS. 
 
 to appear for the first time in the Lower Silurian period, and 
 is well represented in the Upper Silurian. In the Devonian 
 period it attains its maximum of development, and a few Car- 
 boniferous species are known ; but the latter are rare and local 
 in their distribution, and the genus is not known to have sur- 
 vived into the Permian period. 
 
 The genus Cladockonus, M'Coy, was proposed in 1847 (Ann. 
 and Mag. Nat. Hist., ser. i, vol. xx. p. 227) for some Aus- 
 tralian Palaeozoic corals, having " some relations to Aulopora" 
 but differing " in their curious erect habit, regular angular mode 
 of branching, slender, equal, stemlike tubes, and abruptly-dilated 
 terminal cups bent in nearly opposite directions." He further 
 states that the curious little Carboniferous corals which he had 
 formerly referred to Lamoroux's genus Jania (Syn. Carb. Foss. 
 of Ireland, 1844) are really to be placed in the genus Clado- 
 ckonus. There seems, further, to be no reasonable doubt that 
 the genus Pyrgia, Edwards and Haime (Pol. Foss. des Terr. 
 Pal., p. 310, 1851), is really founded upon forms of Cladockonus, 
 M'Coy, and that it must therefore be withdrawn in favour of 
 the latter. My friend Mr R. Etheridge, jun., and myself have 
 prepared a paper 1 dealing with the structure and relations of 
 some of the forms of Cladockonus, and we find that besides 
 species which may be retained in Cladockonus, the genus con- 
 tains at least one very peculiar type (viz., C. crassus, M'Coy), 
 which must be considered as generically distinct, and to which 
 we have given the name of Monilopora crassa, M'Coy, sp. In 
 a typical species of Cladockonus, such as the Carboniferous C. 
 (Pyrgia) Michelini, E. and H., the corallum has the form of a 
 slender erect branching colony, composed of long conical coral- 
 lites (fig. 31, A and B), which are produced from one another by 
 lateral budding, the entire growth being fixed basally to some 
 foreign object by one or more isolated points of attachment. 
 An excellent description of this singular coral is given by De 
 Koninck (Nouv. Rech. sur les An. Foss., p. 153, PI. XV., fig. 
 
 1 Since the above was written this paper has been published (see Geol. Mag., 
 Dec. ii. vol. vi., July 1879). 
 
AULOPORID^E. 223 
 
 6, 1872), and this accurate observer states that the visceral 
 chambers of the corallites are entirely hollow, and that they 
 communicate freely with one another by their bases. This 
 latter point is doubtless correct ; but Mr R. Etheridge, jun., 
 and myself have made thin sections of specimens from the 
 Carboniferous of Scotland which we are unable to distinguish 
 
 o 
 
 from C. Michelini, E. and H., and we find that in these the 
 visceral cavities of the corallites are intersected by a few 
 remote, delicate, complete tabular, which are either straight or 
 slightly curved (fig. 31, c). It would appear, then, that so far 
 as at present known there is nothing in the internal structure 
 of Cladockonus, M'Coy (^ Pyrgia^ Edw. and H.), which would 
 separate it from Aulopora, Goldf., and the generic distinctness 
 of the two can only rest upon the feature that the corallum of 
 the former is erect, whereas in the latter it is creeping and 
 parasitic. So far as known, the species of Cladochonus appear 
 to be exclusively Carboniferous. 
 
 Lastly, it remains to say a few words upon the singular 
 genus Monilopora, Nich. and Eth. jun., which includes only 
 the curious M. (Cladochonus] crassa, M'Coy, sp., of the Carbon- 
 iferous rocks. In this singular form the corallum (fig. 32, A) is 
 decidedly "Auloporoid" in its general appearance, consisting of 
 a creeping tubular basis, which at intervals throws up curved 
 conical corallites, which are of much larger size than is usual in 
 Aulopora, and are free throughout the whole or the greater part 
 of their height. As a rule, the corallum commences in the form 
 of a ring of such corallites, with their connecting basal stolons, 
 encircling the column of a Crinoid like a necklace ; and by the 
 continued growth of the latter the colony often becomes entirely 
 buried within the stem of the Crinoid, only the calices appear- 
 ing on the surface. Adult examples, again, often lose a good 
 deal of this ring-like arrangement, and present themselves as a 
 confused aggregation of corallites quite resembling a magni- 
 fied Aulopora. The minute structure of Monilopora, as eluci- 
 dated by means of thin sections, has been shown by Mr 
 Rofe (Geol. Mag., vol. vi. p. 352, 1869), and subsequently 
 
224 
 
 TABULATE CORALS. 
 
 more fully by Mr R. Etheridge, jun., and myself, to be of a 
 most remarkable character. The entire visceral cavity of each 
 polype is open from top to bottom, and we have been unable to 
 
 Fig. 32. A, A full-grown colony of Monilopora crassa, M'Coy, sp., growing upon the stem of 
 a Crinoid, of the natural size. B, A younger colony of the same, encircling a Crinoidal 
 column, viewed from above, of the natural size. C, A detached fragment of the corallum 
 of the same, of the natural size. D, Transverse section of a young colony of the same 
 growing upon a Crinoidal column, enlarged two and a half diameters. (The visceral 
 chambers of the corallites are largely filled with matrix, and the peculiar reticulated tissue 
 of the skeleton is here and there visible in the wall, while the whole has been finally en- 
 veloped by the growth of the stem of the Crinoid.) E, Longitudinal section of a single 
 corallite of the same, enlarged five diameters, showing the open visceral chamber, the 
 fibrous wall, and the reticulated structure of the wall of the calice. F, A portion of the 
 reticulated tissue still further enlarged. Carboniferous Limestone of Lancashire (British 
 Museum.) 
 
 detect any traces of tabulae (fig. 32, D and E). The wall of the 
 theca is exceedingly thick, and throughout the greater part of 
 its extent it seems to consist wholly of delicate concentric layers 
 of sclerenchyma firmly united with one another. In parts of 
 the corallite, however, and especially as the calice is approached, 
 the concentric lamellae of the wall become separated from one 
 another, so as to include a series of distinct interspaces or 
 cavities, which are approximately parallel to the axis of the 
 visceral chamber, diverging slightly outwards, and which are 
 
AULOPORID^. 225 
 
 crossed at right angles by numerous delicate cross-bars or tra- 
 beculae of sclerenchyma (fig. 32, E and F). This extraordinary 
 reticulate tissue is present in the calicine wall of all specimens 
 of Monilopora crassa which have hitherto been examined, but 
 no similar structure is known to occur in any other coral, nor 
 does it seem possible to offer any probable suggestion as to its 
 functions or homologies. Apart from this unprecedented fea- 
 ture, Monilopora can only be separated from Aulopora by the 
 total absence of tabulae, such as exist in, at any rate, some of 
 the latter, if not in all. 
 
 As to the affinities of the Auloporidce, it appears hazardous 
 at present to give any definite opinion. If I am right in refer- 
 ring Syringopora to the Perforate Corals, then it would not 
 appear that the present group can have any real alliance with 
 the Syringoporidce ; and its relationship with any other division 
 of " Tabulate Corals " would seem to be even more remote. 
 Perhaps the most probable conjecture is that which would look 
 upon the Auloporidcz as a peculiar group of the Alcyonaria. 
 
226 
 
 CHAPTER X. 
 
 HALYSITID^E AND TETRADIID^E. 
 HALYSITID^E. 
 
 THE group of the Halysitida constituted, in the system of 
 Milne- Ed wards and Haime, a sub-family (Halysitince) of the 
 family Chatetidce, and it contained the five genera Halysites, 
 Syringopora, Thecostegites, Chonostegites, and Fletcheria. The 
 last four of these have been already treated of; and there re- 
 mains, therefore, only the genus Halysites itself as the type and 
 sole representative of the family, which may be defined as com- 
 prising coralla composed of long cylindroidal tabulate corallites, 
 which are always more or less extensively united with one 
 another, but have imperforate walls, and exhibit neither mural 
 pores nor connecting-tubes. Spiniform septa may or may not 
 be present, and there may or may not be two diverse sets of 
 corallites. As the family comprises only the single genus 
 Halysites, any remarks as to its systematic position will be best 
 deferred until the characters of the genus have been discussed. 
 
 Genus HALYSITES, Fischer, 1813. 
 
 (Zoognosia, 3d ed, t. i. p. 387.) 
 Catenipora, Lamarck, Hist, des An. sans Vert., t. ii. p. 206, 1816. 
 
 Gen. Char. Corallum fasciculate and reticulate, composed of 
 long tubular cylindroidal corallites, which are placed side by side 
 in intersecting and anastomosing laminae or lines, any given cor- 
 
HALYSITIDJ& AND TETRADIID&. 227 
 
 allite being united along its whole length with its neighbours to 
 the right and left, and each lamina of the corallum consisting 
 of no more than a single linear series of tubes. Each tube is 
 enclosed in a strong imperforate wall surrounded on its free 
 sides by a thick epitheca, and there is usually a distinct divi- 
 sion of the corallites into two series of different sizes, in which 
 case a single small tube is placed between each pair of the 
 larger tubes. Septa may be obsolete, and, when present, have 
 the form of vertically-disposed rows of spines in cycles of 
 twelve. The tabulae are well developed, complete, not in- 
 fundibuliform nor vesicular, the smaller tubes (when present) 
 being more closely tabulate than the larger ones. 
 
 Obs. The general form of the corallum in Haly sites is con- 
 stant in all the known species of the genus, and is too well 
 known to need special description. Every corallite in the 
 corallum, except those which form the actual circumference, is 
 united along its whole length, along opposite sides, to two other 
 corallites, those which form the centre of three of the constitu- 
 ent laminse of the mass being similarly united to three of their 
 neighbours. This union is, moreover, not one of mere contact, 
 but is absolute, the epitheca and wall of any given tube being 
 directly continuous with the corresponding structures in the 
 tubes which stand to the right and left of it (PI. XI., fig. i). 
 The most extraordinary feature in the organisation of Haly- 
 sites, however, concerns the mode by which the lateral union of 
 the ordinary corallites of Haly sites is effected. If we make a 
 thin transverse section of the form usually known as H. eschar- 
 oides, Lam. (PI. X., fig. 6), we find, as just remarked, that the 
 epitheca and walls of neighbouring tubes are absolutely con- 
 tinuous ; but we observe, further, that the epitheca does not take 
 any part in the formation of the partition which actually divides 
 any tube from its neighbour on either side. On the contrary, 
 the partition in question is formed solely by the coalescent walls 
 of the two contiguous corallites, and it is always of a lighter 
 colour and apparently less compact texture than the rest of the 
 tube. We have, therefore, here the singular fact that each tube 
 
228 TABULATE CORALS. 
 
 is enclosed by the epitheca only on its two free sides. In the 
 form known as H. escharoides, Lam., all the tubes are of ap- 
 proximately equal size ; but if, on the other hand, we make a 
 thin transverse section of an example of the typical H. catenu- 
 laria, Linn., we shall find a still more interesting and curious 
 condition of parts (PI. X., fig. 7, and PI. XI., fig. i). In these 
 cases the epitheca and proper walls of the corallites are directly 
 continuous (as in H. escharoides), but there is now the additional 
 feature that between each pair of the normal corallites there is 
 intercalated a much smaller sub-quadrate tube, which forms the 
 medium of union between the former. This interstitial tube, 
 moreover, does not seem to be bounded laterally by an inward 
 prolongation of the walls of the large tubes (as one would 
 expect it to be), but it appears to be enclosed by a proper 
 and peculiar wall of its own on the two sides where the large 
 tubes on either side come against it ; and this proper wall is 
 at once distinguished under the microscope from the wall of 
 the large tubes by its much darker colour and seemingly differ- 
 ent texture (see PI. XI., fig. i). There are thus shown to 
 exist two distinct sets of corallites in H. catenularia, Linn., 
 which occupy fixed and invariable relations to one another, 
 and can be proved by long sections to possess a marked differ- 
 ence in internal structure. Thus the large or normal corallites 
 of this species (PI. X., fig. 8, and PL XI., i a) have curved 
 or nearly straight complete tabulae, regularly and comparatively 
 remotely disposed. On the other hand, the small interstitial 
 tubes are intersected by much more numerous and more closely- 
 set tabulae, which are sometimes straight and sometimes sub- 
 vesicular, the condition of parts thus closely resembling what 
 is observed in the large and small corallites of Heliolites and its 
 allies. 1 In Haly sites escharoides ; as we have seen, the small 
 
 1 So far as I know, Hall first noticed the occurrence of the small closely tabulate 
 tubes between the larger ones, as he says, in his description of H. agglomerata, that 
 the " spaces between the tubes" are " cellular" (Pal. N.Y., vol. ii. p. 129, 1852), and 
 he clearly figures the closely tabulate intermediate tubes. The first clear and at all 
 complete account of this subject appears to have been given by Fischer-Benzon in a 
 paper, " Ueber Halysites," to which I have unfortunately been unable to obtain 
 
HALYSITID^E AND TETRADIID^E. 229 
 
 interstitial tubes so far as my observations go seem to be 
 wanting ; but I have never failed to recognise their existence 
 in H. catenularia, Linn. ; and they are especially well developed 
 in all specimens of H. agglomerata, Hall, which I have ex- 
 amined. 
 
 With regard to the septa of Haly sites, the condition of parts 
 varies greatly in different forms of the group. In those forms, 
 namely, which are usually referred to H. catenularia, Linn., I 
 have never succeeded in recognising in microscopic sections 
 any traces whatever of septa, except that the lateral walls of 
 the intermediate or small corallites often carry small projec- 
 tions apparently of a septal nature (PI. XI., fig. i). On the 
 other hand, in the forms which are usually known as H. 
 escharoides, Lam., there are always well -developed spiniform 
 septa, of exactly the same type as in the Favositidce and 
 Syringoporidce. These septa are arranged in vertical rows, 
 the number of which seems to be constantly twelve in each 
 corallite. 
 
 I do not intend here to give any description of any of the 
 species of Halysites, especially as I am unable to make up my 
 mind as to the true relations of H. catenularia and H. eschar- 
 oides to one another. Till now I have ventured to differ from 
 such distinguished authorities as Milne-Edwards and Haime, 
 and have always considered these as mere varietal forms, since 
 I have looked upon the sole alleged differential characters 
 viz., the size of the tubes and the dimensions of the meshes of 
 the corallum as purely varietal characters. By means of micro- 
 scopic sections, I have satisfied myself so far as my material 
 goes that the form known as H. escharoides, Lam., is distin- 
 guished from the typical H. catenularia, Linn., not only by 
 the superficial characters just mentioned, but also by the con- 
 stant possession of spiniform septa, and the apparently constant 
 absence of small tubes between the larger one. As these dif- 
 
 access, but this observer does not seem to have recognised the true nature of the 
 interstitial tubes. To Dr Lindstrom, therefore, is due the credit of having pointed 
 out that the corallum si Halysites, as of Heliolites, consists of two distinct sets of 
 zooids (Ofversigt af Kongl. Vetenskaps Akad. Forhandl., 1873). 
 
2 3 o TABULATE CORALS. 
 
 ferential characters are fundamental ones, it may seem ridicu- 
 lous to doubt any longer the specific distinctness of H. eschar- 
 oides and H. catenularia. The two forms, however, are so re- 
 markably similar in most respects, are so variable in external 
 characters, and are so constantly associated together, that I am 
 still almost disposed to conjecture that they are the different 
 conditions of a dimorphic species, and that their differences 
 are due to something else than specific distinctness. 
 
 As regards the affinities and zoological position of Halysites, 
 the above account of its structure leaves little doubt that the 
 genus is more nearly allied to the Heliolitidcz than to any 
 other. Halysites agrees with Heliolites and the recent Helio- 
 pora in possessing (usually) two distinct sets of corallites, large 
 and small, the two being distinguished further by the arrange- 
 ment of their tabulae ; and there can be no reasonable doubt 
 that this indicates that each colony of the typical H. catenularia, 
 Linn., consisted of two structurally and functionally distinct sets 
 of zooids. On the other hand, I cannot accept the view of Dr 
 Lindstrom (Ann. Nat. Hist., ser. iv., vol. xviii. p. 13), who 
 actually places Halysites among the Heliolitid<z. It appears 
 to me, on the contrary, to form a quite special group, distin- 
 guished from Heliolites and its allies, not only by the unique 
 form of the corallum, but also by the great reduction, or, it 
 may be, total absence, of the smaller zooids, by the frequent 
 absence of septa, and by the fact that the septa (when present) 
 are spiniform, and present no resemblance to the "pseudo-septa" 
 of the Helioporidce. If the view that Halysites is nearly allied 
 to the Helioporidce be accepted, then it follows that the family 
 of the Halysitidcz will have to be considered as a distinct and 
 ancient group of the Alcyonaria ; but it will still remain certain 
 that no true relationships have been shown to exist between 
 Halysites and the Tubiporidce, with which family the genus has 
 often been associated. 
 
 The geological range of Halysites, so far as known, is an 
 extremely limited one, the first representatives of the genus 
 appearing in the later portion of the Lower Silurian period, 
 
HALYSITID^. AND TETRADIID^E. 231 
 
 while the maximum development of the genus is attained in 
 the Upper Silurian, and no Devonian species has been as yet 
 detected. 
 
 TETRADIID^E. 
 
 This group includes only the Silurian genus Tetradium, 
 Dana, and its probable systematic place will be best discussed 
 after some description of the genus has been given. The 
 fullest account of the genus which has yet been published is 
 one which was given by Mr R. Etheridge, jun., and myself 
 (Ann. and Mag. Nat. Hist, sen iv., vol. xx. p. 162, 1877) ; and 
 the following brief analysis of the chief characters of Tetradium 
 is for the most part extracted from the memoir just referred to. 
 
 Genus TETRADIUM, Dana, 1846. 
 (Wilkes's Expl. Exped. Zoophytes, p. 701.) 
 
 Gen. Char. Corallum massive, composed of long prismatic 
 and closely contiguous corallites, the walls of which are not 
 pierced by mural pores or other foramina. The septa are 
 distinct, few in number, most typically four, short, not reach- 
 ing the centre of the visceral chamber, and seeming as if 
 formed by inflections of the wall. Calices generally petaloid, 
 as are the corallites in transverse section. Tabulae numerous, 
 complete. Increase apparently by fission of the old tubes. 
 
 ' Obs. The genus Tetradium was founded by Professor Dana 
 for the reception of a fossil of uncertain locality in the collection 
 of Yale College, New Haven ; and the following characters were 
 ascribed to it : " Coralla massive, consisting of four-sided tubes 
 and cells, with very thin septa or parietes ; cells stellate, with 
 four narrow laminae." 
 
 At a subsequent date, Professor J. M. Safford described four 
 species of corals from the Lower Silurian Rocks, which he re- 
 ferred to this genus (Amer. Journ. Sci. and Arts, ser. 2, vol. 
 xxii. p. 236) ; and he supplemented Dana's description with 
 
2 3 2 TABULATE CORALS. 
 
 the following remarks : " The tubes in the different species 
 vary from one quarter of a line to nearly one line in breadth ; 
 they are very long, and are most frequently united throughout 
 laterally, forming massive coralla, resembling more or less those 
 of Favosites and Ch&tetes ; sometimes, however, they are united 
 in single intersecting series, as in Haly sites catenulata, Linn. ; 
 not unfrequently, too, the tubes are isolated, or only united at 
 irregular intervals, thus forming loose fasciculated coralla, re- 
 sembling certain forms of Syringopora" 
 
 Professor Safford further states that the isolated tubes are 
 nearly quadrangular, with more or less rounded angles, and 
 with a slight external longitudinal depression opposite to each 
 of the four septa ; the walls are more or less rugose ; and in- 
 crease is by fission of the old tubes. Only one specimen was 
 seen in which tabulae could be detected ; and in this they were 
 confined to one end of the mass, and were distant from one 
 another about twice the width of the tubes. 
 
 The genus Tetradium is regarded by Safford as intermediate 
 between the Favositidcz and the Rugosa, the quadripartite char- 
 acter of the corallites placing it in the latter group. 
 
 Taking such a well-known species as the T. minus, Saff., of 
 the Cincinnati Group, as the type of the genus Tetradium, we 
 find that the corallum (fig. 33, A) is massive, hemispherical, 
 or irregular in shape, and composed of closely amalgamated, 
 slender, prismatic corallites, which diverge from the base or 
 from an imaginary axis, and are not arranged in superimposed 
 layers. No general epitheca seems to be present. The coral- 
 lites are in close contact throughout their length, and their walls 
 appear to be entirely imperforate. Some doubt, however, must 
 in the meanwhile remain upon this point, owing to the fact that 
 all the microscopic sections I have made (of specimens derived 
 partly from Ohio and partly from Canada) show the walls to have 
 undergone a very peculiar change. The walls of the corallites, 
 namely though the specimens appear otherwise to be quite 
 unaltered have the normal granular carbonate of lime which 
 composes the Ccelenterate skeleton replaced by crystalline cal- 
 
HALYSITIDsE AND TETRAD1ID.E. 
 
 233 
 
 cite. Hence we could hardly hope to detect mural pores, even 
 if such structures had at one time existed. For the same reason 
 it must remain doubtful whether or not the walls of contiguous 
 corallites are actually amalgamated with one another. Mr 
 Etheridge and myself arrived at the conclusion that the walls 
 were really double (as in Favorites) ; but we based this opinion 
 chiefly upon the apparent exposure of the exterior of the 
 tubes in some fractured specimens, and I have subsequently 
 seen reason to think that the appearances in question are not 
 constant. I still think that the walls are really double ; but as 
 the microscopic evidence is not conclusive, I can only leave the 
 point an open one. 
 
 The most characteristic feature in the corallum of Tetradium, 
 which separates it, even to superficial inspection, from that of 
 a massive Chcetetes, is the conspicuously cruciform or petaloid 
 form of the calices or of transverse sections of the corallites 
 (fig. 33, B). This petaloid form is due to the presence of four 
 delicate lamellar septa, which look as if formed by inward fold- 
 
 Fig. 33. A, Fragment of a large corallum of Tetradiwn minus, Safford, from the Cincinnati 
 Group of North America, of the natural size ; B, Transverse section of the same, enlarged 
 ten times, showing the petaloid form of the tubes and the short septa ; c, Vertical section 
 of the same similarly enlarged, showing the tabulae. 
 
 ings of the wall, and which extend for a short distance only 
 towards the centre of the visceral chamber. Normally, and 
 most generally, four of these septal laminae are present, but 
 their number is not constant, and varies from one to five. 
 The only other special point brought out by sections is, that 
 
234 TABULATE CORALS. 
 
 the visceral cavities of the polypes are intersected by numer- 
 ous complete tabulae, which are straight and horizontal, and 
 entirely independent of each other (fig. 33, c). 
 
 As regards the systematic position of Tetradium, the known 
 peculiarities in its structure seem to render three conclusions 
 more or less certain : (i) That SafFord's conjecture as to the 
 Rugose affinities of the genus is entirely untenable ; (2) that the 
 genus has no strong points of relationship with Chatetes* which 
 it most nearly resembles in general form and habit; and (3) that 
 its true alliances are with Halysites and Heliolites. As regards 
 HalysiteSy the chief points of likeness are to be found in the 
 fact that both genera possess remarkably long tubular imper- 
 forate corallites, and in the fact that both Safford and Billings 
 have indicated that specimens of Tetradium sometimes assume 
 the otherwise unique habit of Halysites, the corallites being 
 united by their lateral margins in single intersecting series. I 
 have never myself been so fortunate as to meet with any speci- 
 mens exhibiting the peculiar mode of growth just alluded to, 
 but it is evident that whatever may be the relationship between 
 Tetradium and Halysites and I do not doubt that there is a 
 relationship the former genus is widely separated by its lamel- 
 lar, not spiniform septa, by the cruciform arrangement of these 
 structures, and by the total absence of any set of small zooids 
 coexisting with those of normal size. On the other hand, 
 Tetradium presents a very striking resemblance to Heliolites 
 in the form of the delicate lamellar septa, which have every 
 appearance of being "pseudo-septa" produced by inflection of 
 the wall. The absence, however, of small zooids, would of 
 itself be quite sufficient to prevent any actual reference of 
 Tetradium to the Helioporida* even if other differences (such 
 as in the number of the septa) did not exist as well. Upon the 
 whole, therefore, it seems best to regard Tetradium, Dana, as 
 the type of a special group of the Alcyonaria, allied to the 
 Halysitidce and the Helioporidce, and yet distinct from both of 
 these. 
 
235 
 
 CHAPTER XI. 
 
 AND HELIOPORID/E. 
 
 THECID^E. 
 
 THE group of the Thecidce, E. and H., comprises only the 
 anomalous Silurian genus Thecia, E. and H., the type of which 
 is the Thecia Swindernana of Goldfuss. It is important to 
 bear this fact in mind, as I shall found the following descrip- 
 tion of the group entirely upon a most careful macroscopic and 
 microscopic investigation into the structure of the type-species 
 of the genus, of which I possess a large number of authen- 
 tic examples, derived from the Wenlock Limestone of both 
 Britain and Sweden. I mention this the more particularly 
 here, because it is needless to say that the diagnosis of a genus 
 must in all cases be ultimately decided by the structural char- 
 acters of the original type of that genus, and cannot be based 
 upon forms which any given observer may believe, - perhaps 
 upon insufficient grounds, to be congeneric with that type. 
 The genus now under consideration illustrates this point in 
 an especial manner, for the last, and in all respects the most 
 circumstantial, account of the genus Thecia, E. and H., which 
 has yet been published (Foss. Cor. of Michigan, p. 65, 1876), 
 ascribes to the genus characters such as do not exist in the 
 type-species, and ignores other fundamental features which are 
 really present in the latter ; and I do not think that so accom- 
 plished an observer as Dr Rominger could have arrived at 
 
236 TABULATE CORALS. 
 
 some of his conclusions, unless it were that some of the forms 
 which he refers to Thecia are really of a different nature. 
 
 The affinities of the family of the Thecida will be best con- 
 sidered after I have given a short account of the structural 
 characters of the genus Thecia; and the group may be in the 
 meanwhile defined as including coralla formed of tubular 
 corallites of two distinct sizes, the larger disposed with con- 
 siderable regularity among the smaller ones. The large coral- 
 lites are tabulate, with indistinctly differentiated walls, provided 
 with obtusely triangular and irregular septa, and having their 
 visceral cavities more or less freely connected with one another 
 by lateral horizontal channels, which penetrate the interstitial 
 tubular tissue. The smaller interstitial tubes are doubtfully 
 tabulate, and their cavities are liable to be largely filled up by 
 a secondary deposit of sclerenchyma. 
 
 Genus THECIA, Edwards and Haime, 1849. 
 Comptes Rend, t. xxix. p. 263. 
 
 Gen. Char. Corallum rarely ramose, usually in the form of a 
 laminar expansion, covered below by a concentrically wrinkled 
 epitheca, and having the calices placed upon its upper surface. 
 Corallites in the main erect and perpendicular to the horizontal 
 axis of the corallum (sometimes slightly curved inferiorly), of 
 two sizes, large and small. The large corallites are placed at 
 regular intervals, and though their visceral chambers are clearly 
 circumscribed, they cannot be said to be bounded by distinctly 
 differentiated walls ; but they are, on the contrary, embedded 
 in a dense tissue composed of the smaller tubular corallites, 
 which may open on the surface by means of irregular, often 
 stelliform apertures, or may be to a large extent closed by a 
 secondary deposit of sclerenchyma. The smaller corallites are 
 primitively bounded by distinct polygonal walls, and it is not 
 certain if they are tabulate. On the other hand, the large 
 corallites are distinctly tabulate, are provided with irregular 
 
THECID& AND HELIOPORID^. 237 
 
 and obtuse lamellar septa, and communicate directly with one 
 another by means of tortuous horizontal channels passing from 
 one to another. No columella is present. 
 
 Obs. Owing to the great density of its tissues, the diffi- 
 culties in the way of making a thorough examination of the 
 structure of Thecia by means of the microscope l are unusually 
 great, and it has been only by means of a large series of thin 
 sections that I have been enabled to come to any satisfactory 
 conclusions as to its minute anatomy, while there still remain 
 some points of importance which I have found it impossible to 
 clear up. The corallum in the type-species, T. Swindernana, 
 Goldf. sp., has the form of a laminar, usually discoid expansion, 
 attached by the centre of its base to some foreign body, and 
 having the whole of the lower surface covered by a concentri- 
 cally striated and wrinkled epitheca. The upper surface carries 
 the calices, and when examined macroscopically, even by means 
 of a lens, usually shows nothing but the stellate apertures of 
 the larger corallites, which are from a third of a line to half a 
 line in diameter, and are separated by what appears to be an 
 equal width of dense interstitial tissue. This interstitial tissue 
 is marked superficially by numerous minute, radiating, often 
 vermicular grooves, which extend from each calice to the neigh- 
 bouring ones (PL XI., fig. 2), and it was regarded by Milne- 
 Edwards and Haime as being of the nature of a " spurious 
 ccenenchyma, resulting from the intimate union of the costse " 
 (Brit. Foss. Corals, p. 278). As there are no costse in Thecia, 
 Milne-Edwards and Haime were, of course, in error in suppos- 
 ing this interstitial tissue to be formed by the coalescence of 
 structures of this nature ; but in the sense in which they used 
 the term " coenenchyma," they were undoubtedly right in 
 supposing that they were dealing here with a " coenenchymal " 
 tissue. In other words, there can be no doubt as to the identity 
 of the interstitial tissue of Thecia with the so-called " ccenen- 
 
 1 Though in the habit of preparing all my own sections for the microscope, I was 
 compelled in this instance to have resort to the skill of Mr F. G. Cuttell; and I have 
 therefore had the advantage of probably the most beautiful sections of this difficult 
 form which could be prepared at the present day. 
 
238 TABULATE CORALS. 
 
 chymal tubuli " of Heliolites and its allies, which we only know 
 by the quite recent researches of Moseley to be not truly of a 
 ccenenchymal nature. When, in fact, we examine exceedingly 
 thin sections of Thecia, whether these be either transverse or 
 longitudinal, we find that the apparently dense and compact 
 tissue which seems to separate the large corallites is in truth 
 composed of vertical tubules, which we must now regard 
 from what we know of the Helioporidce as being properly 
 small corallites, tenanted by a special set of zooids. So far, 
 then, the structure of Thecia is essentially identical with that 
 of Heliolites, but there are some very important differences to 
 be observed in these types respectively. In Heliolites and its 
 relatives, both the larger and the smaller corallites are enclosed 
 by thin but perfectly distinct walls, the former having well- 
 developed septa and remote tabulae, the latter having no septa 
 and crowded tabulae ; while there is no sufficient evidence of 
 any lateral communication between the visceral cavities of the 
 larger corallites. In Thecia, on the other hand, the large coral- 
 lites cannot be proved, even in the thinnest sections, to possess 
 any proper wall, their boundaries not being clearly separable 
 from the dense tubes of the interstitial tissue ; the septa which 
 they possess are not at all similar to the thin inflections of the 
 wall which constitute the " pseudo-septa " of Heliolites and its 
 allies, but are thick and irregular ridges ; while the interstitial 
 tubuli so far as can be certainly ascertained are destitute of 
 tabulae. There is, moreover, the curious feature that the larger 
 corallites are placed in direct communication by means of dis- 
 tinct, often tortuous, horizontal channels, which traverse the 
 interstitial tubuli. 
 
 If we examine a thin transverse section of Thecia Swinder- 
 nana under the microscope (PI. XL, figs. 2 a, 2 <), we observe 
 that the visceral chambers of the large corallites are quite dis- 
 tinctly marked out, though nothing of the nature of a differen- 
 tiated bounding- wall can be detected. Here and there the 
 visceral cavities of two contiguous polypes may be seen to be 
 directly connected by a horizontal canal, which happens to have 
 
THECID^E AND HELIOPORID^E. 239 
 
 been placed in the plane traversed by the section. The septa 
 appear simply as blunt, triangular, irregular lateral ridges, with 
 ill-defined margins, having deep sulci at their bases, but always 
 leaving a considerable central area into which they do not pene- 
 trate. The interstitial tissue presents different appearances in 
 different parts, or under different conditions of preservation. 
 Sometimes though by no means always the interstitial tissue 
 can be recognised as divided into a number of small polygonal 
 areas by a network of dark lines, which represent the primitive 
 walls of the interstitial tubuli. Often these walls can only be 
 recognised by the slightly thickened nodes at their angles of 
 junction, or they may not be capable of detection at all. In the 
 same way, the minute central cavities of the interstitial tubuli 
 may appear in cross-sections as so many minute, irregular, 
 sometimes stelliform apertures, or they may be filled with 
 granular sclerenchyma, when the interstitial tissue appears 
 to be wholly solid. 
 
 In longitudinal sections (PL XI., figs. 2 c, 2 </), the visceral 
 cavities of the larger corallites are distinctly marked out, as 
 before, without any clearly-defined wall, and are seen to be 
 intersected by well - developed complete tabulae, which are 
 slightly flexuous, and sometimes anastomose to some extent 
 with each other; while occasionally the section exhibits a 
 portion or the whole of one of the horizontal canals placing 
 contiguous tubes in communication. In sections of this nature, 
 the composition of the apparently dense interstitial tissue out 
 of numerous closely-approximated vertical tubuli can always 
 be recognised without the slightest difficulty. Moreover, these 
 tubuli, in sections of sufficient thinness, can always be recog- 
 nised as being bounded by perfectly distinct, apparently double 
 walls ; but their cavities appear to be more or less extensively 
 obliterated by a deposit of granular, not laminated sclerenchyma, 
 which seems, however, to be very irregularly distributed. No 
 tabulae can be detected, though it is possible that such struc- 
 tures really existed. 
 
 From a consideration of the above characters, it will be 
 
2 40 TABULATE CORALS. 
 
 evident that Dr Lindstrom had much ground for his suggestion 
 (Ann. Nat. Hist, ser. 4, vol. xviii. p. 13) that Thecia is closely 
 allied to the Heliolitida. As has been already pointed out, 
 however, there exist certain very important differences between 
 Thecia and Heliolites, which are of too fundamental a nature to 
 permit of our associating these genera in a single family. Of 
 these differences, the most important is the presence in the 
 former genus of distinct and well-developed horizontal canals, 
 which traverse the interstitial tissue, and place the visceral 
 cavities of neighbouring polypes in direct communication This 
 feature is one in which the genus approaches the Perforate 
 corals in general, and the Favositidce in particular ; but the 
 latter are fundamentally distinguished by the total absence of 
 anything analogous to the interstitial tubuli of Thecia. Upon 
 the whole, therefore, the best course to follow is to place Thecia 
 in a distinct family Thecid<z, E. and H. which will occupy a 
 position in the Alcyonaria close to the Helioporidce ; and in so 
 doing we may remember that though the horizontal canals 
 above spoken of recall to our minds the " mural pores " of 
 the Favositidce and the hollow " connecting-processes " of the 
 Syringoporidcz, the existence of a direct connection between 
 the visceral cavities of neighbouring polypes is a common 
 feature in the Alcyonarian Zoophytes. Before leaving the 
 subject of the affinities of the genus Thecia, a few words may 
 be said as to the views which Dr Rominger has expressed upon 
 the same point (Foss. Cor. of Michigan, p. 65). According to 
 this observer, Thecia has "the general structure of Favosites ; " 
 the walls of the corallites are thick, and are bounded by " de- 
 fined polygonal outlines," but occasionally " the walls do not 
 exceed in thickness those of an ordinary Favosites ;" the septa 
 are spiniform, and extend nearly to the centre of the visceral 
 chamber ; and " large and abundant " lateral pores (i.e., mural 
 pores) are present. The figures given by Dr Rominger, beauti- 
 ful as they are, being heliotypes, present the specimens of the 
 natural size, and give one no clue as to their real internal struc- 
 ture. Not having seen Dr Rominger's specimens, it would be 
 
THECID^E AND HELIOPORID^E. 241 
 
 useless to criticise his diagnosis of the genus in detail. I can 
 only say, therefore, that the structure of the type-species, T. 
 Swindernana, Goldf. sp., as above described, is such as to render 
 it apparently impossible that the forms ascribed to Thecia by 
 Dr Rominger can really be congeneric with it. In fact, Thecia 
 Swindernana does not agree in any important respect with 
 Thecia as defined by Dr Rominger, and especially differs in the 
 characters which I have above enumerated. If Dr Rominger, 
 therefore, has not been misled by the examination of specimens 
 greatly altered by fossilisation, it is clear that the species de- 
 scribed by him under the name of Thecia must belong to some 
 other generic type. Lastly, Dr Rominger asserts that Prot- 
 arcza, E. and H., possesses corallites which have mural pores, 
 and are provided with convex tabulae, and that it is a near ally 
 of Thecia. On this point, I can only say that I have failed to 
 discover any traces of tabulae in Protarcea, either in actual 
 specimens or in thin vertical sections ; that though the walls 
 are porous, there are no " mural pores," properly so called, in 
 any examples I have seen ; and that I am unable, therefore, to 
 accept the view that any alliance exists between this genus and 
 Thecia. 
 
 So far as at present known, the gen-us Thecia is confined in 
 its geological range to the Upper Silurian rocks, the type- 
 species, T. Swindernana, Goldf., being an abundant and charac- 
 teristic fossil of the Wenlock Limestone of Britain and Sweden. 
 
 HELIOPORID^E (Moseley). 
 
 This well-defined and distinctly circumscribed group of corals 
 is characterised by the possession of a corallum composed of 
 two distinct sets of corallites, tenanted in life by two distinct 
 sets of zooids. The larger tubes are uniformly distributed 
 among a very much larger number of much smaller ones, and 
 are provided with delicate lamellar septa (" pseudo-septa"), 
 which are formed by infoldings of the wall, are typically twelve 
 in number, and are occasionally rudimentary or even obsolete. 
 
 Q 
 
242 TABULATE CORALS. 
 
 The visceral cavities of the polypes are also crossed by com- 
 plete, more or less horizontal tabulae. The smaller corallites 
 are typically provided with distinct walls, which may, however, 
 be rudimentary ; and they have their internal cavities intersected 
 by horizontal or strongly convex tabulae, while septa are en- 
 tirely wanting. No lateral channels exist in any of the fossil 
 forms (so far as known), by which the visceral cavities of the 
 larger corallites are placed in communication with one another, 
 or with the cavities of the smaller corallites. 
 
 From the researches of Mr Moseley (Phil. Trans., vol. 
 clxvi p. 92, 1876), we know that Heliolites and its allies are 
 essentially similar as regards the structure of the corallum to 
 the living Heliopora, and we have therefore the right to con- 
 clude that this resemblance extended to the soft parts as well. 
 We have therefore every right to conclude that Heliolites and 
 its relations were Alcyonarian Zoophytes, with polypes of two 
 different kinds, the fully-developed zooids inhabiting the larger 
 tubes of the skeleton, and having eight mesenteries and eight 
 pinnately-fringed tentacles ; while the septa do not correspond 
 in number with the mesenteries, and are consequently to be 
 regarded as " pseudo-septa." The only important point in 
 which Heliolites and the forms related to it appear to differ 
 from Heliopora is that the cavities of the small sexless zooids 
 of the latter genus are stated by Mr Moseley to communicate 
 directly with the body-cavities of the larger corallites ; but we 
 have in the meanwhile no evidence of the existence in the 
 extinct genera of any apertures in the walls of the larger 
 corallites by which such a communication could be effected. 
 This difference, if ultimately established, will be one of great 
 importance ; but a further examination of the fossil forms will 
 be required to prove conclusively that the large zooids pos- 
 sessed no direct communication with the smaller ones. 
 
 The genera included in this family are the Palaeozoic 1 Helio- 
 
 1 The Devonian genus Battersbyia, E. and H. (Pol. Foss. des Terr. Pal., p. 227), 
 originally placed by its founders in the neighbourhood of Heliolites, has been shown 
 by Professor Martin Duncan (Phil. Trans., vol. clvii., 1867) to be a member of the 
 special family of the Palastrceacz, an extinct group of the Zoantharia Aporosa. 
 
THECID^E AND HELIOPORID^E. 243 
 
 lites, Dana, Plasmopora, E. and H., Propora, E. and H., Pinaco- 
 pora, Nich. and Eth. jun., and Z/y//z'tf , E. and H., the Cretaceous 
 PolytremaciS) D'Orb., and the recent Heliopora, De Blainv., of 
 which only the first five concern us here. Fistulipora, M'Coy, 
 which has often been included among the Heliolitidce, appears 
 to me, for reasons which will subsequently be given, to belong 
 rather to the Ch&tetida (or to the Monticuliporidce> if such a 
 family be ultimately established), and I shall consider it in 
 association with Constellaria and Monticulipora. The ^Palaeozoic 
 genera of the Helioporidce are exclusively Silurian and De- 
 vonian, and there is such a close similarity in their general 
 structure that they require but comparatively brief notice. 
 
 Genus HELIOLITES, Dana, 1846. 
 
 (Wilkes's Expl. Exped. Zooph., p. 541.) 
 
 (PL XII., figs. 2-2 a.) 
 
 Gen. Char. Corallum spheroidal, pyriform, hemispherical, 
 or rarely ramose, composed of numerous closely contiguous 
 corallites, which are divisible into two distinct series. The 
 larger corallites are cylindrical, comparatively few in number, 
 and furnished with twelve lamellar infoldings of the wall, of 
 the nature of pseudo-septa, which fall short of the axis of the 
 visceral chamber. Small corallites completely investing the 
 larger ones, more or less regularly polygonal in form, provided 
 with distinct walls, which are completely amalgamated with one 
 another and with the walls of the larger tubes, and which are 
 not known to be provided with any apertures allowing lateral 
 communication. The small tubes have no septa, but have 
 numerous straight and complete tabular, similar but somewhat 
 less numerous structures existing in the large tubes. No 
 columella. 
 
 Obs. The corallum in Heliolites is usually more or less 
 hemispherical or spheroidal in shape, the under surface covered 
 with a concentrically-striated epitheca, and having the calices 
 
244 TABULATE CORALS. 
 
 opening over the whole upper surface. In other cases (e.g., H. 
 Grayi, E. and H.) the corallum is ramose or lobate, fixed by 
 its base, and having the calices covering the whole of the free 
 surface. The internal structure of the corallum can be readily 
 studied in actual specimens or in polished sections, and little 
 fresh information is afforded by thin slices. The most impor- 
 tant points to notice, as differentiating the genus from its im- 
 mediate allies, or as otherwise of interest, are the following : 
 
 The corallites are universally and throughout in complete 
 contact, their walls being so entirely amalgamated that no 
 traces of their originally duplex constitution can be detected. 
 No apertures of the nature of "mural pores" are known to 
 exist in the walls. 
 
 The walls of the larger corallites are folded so as to give rise 
 to twelve septal ridges, which are continuous from the top to 
 the bottom of the visceral chamber, and are not spiniform. In 
 some cases (e.g., H. megastoma, M'Coy) the septa are marginal 
 and rudimentary (PI. XII., fig. 2) ; in other cases they extend 
 inwards for a considerable distance ; but in no case do they 
 actually meet in the centre of the visceral chamber. No septa 
 exist in the smaller corallites. 
 
 The number of the smaller corallites varies much in different 
 species, but there is always enough of them to completely 
 isolate the larger tubes. Usually there are several layers of 
 small tubes between any given pair of the larger tubes, but 
 there are only from two to five rows in H. megastoma, M'Coy ; 
 and there are usually no more than two rows, or only a single 
 one, separating the larger corallites in H. dubia, Fr. Schmidt, 
 and in H. plasmopor aides, Nich. and Eth., jun. 
 
 The smaller corallites of Heliolites are principally distin- 
 guished from the corresponding tubes in Propora and Plasmo- 
 pora by their regularly polygonal shape, and by the fact that 
 their walls are never obsolete, but are completely developed 
 (PI. XII., fig. 2 a). In long sections, therefore, no difficulty 
 is experienced in recognising the walls of the smaller tubes. 
 
 The tabulae are well developed in both the larger and 
 
THECID^E AND HELIOPORID^E. 245 
 
 smaller corallites (PI. XII., fig. 2 a), and in thin sections appear 
 to be of a much darker colour than the actual walls of the 
 tubes. In the small corallites the tabulae are numerous, com- 
 plete, more or less horizontal, and often placed at corresponding 
 levels in contiguous tubes. In the larger corallites the tabular 
 are also complete, and essentially horizontal, but they are 
 placed at somewhat greater distances apart, and they occasion- 
 ally unite with one another. 
 
 I have made an examination by means of thin sections of 
 H. interstincta, Linn., H. Murchisoni, E. and H., H. megastoma, 
 M'Coy, H. porosa, E. and H., and H. Grayi, E. and H. ; 
 but none of these depart in any noticeable feature from the 
 normal type of the genus, or exhibit peculiarities of such 
 importance as to justify special description. The most aber- 
 rant species of the genus which I have examined is a form from 
 the Devonian of Australia, which will be subsequently de- 
 scribed by Mr R. Etheridge, jun., and myself under the name 
 of H. plasmoporoides, and which nearly approaches the genus 
 Plasmopora by its comparatively irregular and comparatively 
 few interstitial tubes. It shows itself, however, to be a true 
 Heliolites by the complete walls of the smaller corallites, and 
 by the fact that the tabulae of these tubes are not curved or 
 vesicular. Another curious type is the Upper Silurian H. 
 dubia, Fr. Schmidt, but I have had no opportunity of investi- 
 gating this species microscopically. 
 
 So far as at present known, all the species of Heliolites are 
 confined to the Lower and Upper Silurian rocks, and to the 
 Devonian. 
 
 Genus PLASMOPORA, Edwards and Haime, 1849. 
 
 (Compt. Rend., t. xxix. p. 262.) 
 (PI. XL, fig. 5, and PI. XII., fig. i.) 
 
 Gen. Char. Corallum discoidal when young, but becoming 
 hemispherical or spheroidal when adult, its lower surface covered 
 
246 TABULATE CORALS. 
 
 by a concentrically-striated epitheca, while the upper surface 
 carries the calices. Corallites in complete contact throughout, 
 divisible into two distinct series. The larger tubes are com- 
 paratively few in number, and possess twelve lamellar septa, 
 formed by infoldings of the wall, and extending but a short 
 distance into the visceral chamber ; while they are crossed by 
 horizontal, complete, and comparatively remote tabulae. The 
 smaller tubes are devoid of septa, are comparatively irregular 
 in form, and only possess distinctly differentiated walls when 
 young. In their adult state their walls become amalgamated 
 with the convex and anastomosing tabulse by which their 
 cavities are intersected, in such a manner that they can no 
 longer be recognised as distinct structures, and the interspaces 
 between the larger corallites become filled up with a loose 
 tissue composed of irregular lenticular vesicles. 
 
 Obs. In almost all the essential features of its anatomy, 
 Plasmopora entirely resembles Heliolites, and it is only neces- 
 sary here to make a few remarks on the sole character by which 
 the two genera can be separated namely, the peculiar struc- 
 ture of the smaller tubes. In Heliolites, as we have seen, the 
 smaller corallites are polygonal in shape, have perfectly distinct 
 walls, and are crossed by essentially horizontal tabulae, which, 
 though often placed at the same level in neighbouring tubes, 
 do not actually coalesce with one another laterally. In very 
 young specimens of Plasmopora petaliformis, E. and H., the 
 only species of the genus that I have examined by means of 
 thin sections the condition of parts is so far like that of 
 Heliolites that the walls of the smaller corallites are perfectly 
 recognisable (PI. XII., fig. i) in long sections ; but there is this 
 difference, that the tabulae are now very highly convex, and are 
 either continued into one another, or are joined with the walls 
 of the tubes in such a manner as to give rise to an apparently 
 continuous vesicular tissue, which fills all the spaces between 
 the larger corallites. In older coralla this amalgamation of the 
 curved and inosculating tabulae with the walls of the tubes has 
 gone so far, that the latter almost or quite disappear. Hence, 
 
THECID^E AND HELIOPORID^E. 247 
 
 when we examine tangential sections of the corallum (PI. XI., 
 fig- S)> we fi n d that the polygonal and comparatively regular 
 tubes of Heliolites are replaced by quite irregular spaces, of 
 very variable size, surrounded for the most part by curved 
 boundaries, which represent the cut edges of the component 
 vesicles of the interstitial tissue. 
 
 With the exception of the imperfectly characterised Plasmo- 
 pora micropora (Goldfuss), E. and H., which is believed to be 
 from the Devonian of the Eifel, all the species of this genus 
 are Silurian in their range. 
 
 Genus PROPORA, Edwards and Haime, 1849. 
 
 (Compt. Rend., t. xxix. p. 262.) 
 
 (PL XI, figs. 3-3 A) 
 
 Gen. Char. Corallum discoidal, hemispherical, or irregularly 
 spheroidal, the lower surface covered with a concentrically- 
 striated epitheca. Corallites of two sizes : the larger ones with 
 distinct walls, which are infolded so as to form twelve short 
 septal ridges, the visceral chamber being intersected by com- 
 paratively remote, complete, approximately horizontal tabulae. 
 Smaller corallites with altogether obsolete walls, these struc- 
 tures being undistinguishably amalgamated with the convex 
 tabulae, so that the narrow interspaces between the larger tubes 
 become filled up with a vesicular tissue formed of lenticular 
 cells. Calices slightly exsert. 
 
 Obs. I am quite disposed to agree with Dr Lindstrom 
 (Ann. Nat Hist, ser. 4, vol. xviii. p. 16) in thinking that 
 Propora can hardly be kept generically distinct from Plas- 
 mopora. The mere fact that the larger corallites are slightly 
 exsert can hardly be regarded as of generic importance ; and 
 an examination of thin sections of Propora tubulata, E. and 
 H., has led me to take a different view of the condition of the 
 septa to that propounded by Edwards and Haime. These 
 high authorities believed that the twelve short septa of the 
 
248 TABULATE CORALS. 
 
 larger corallites were prolonged exteriorly into " costse " (Pol. 
 Foss. des Terr. Pal., p. 223); but I do not think that any 
 structures to which this name could be properly applied are 
 really present. On the contrary, I believe that the apparent 
 " costse " are in reality as also in Plasmopora nothing more 
 than the imperfectly-developed walls of the smaller interstitial 
 corallites. In the structure of the large corallites, Propora 
 differs in no respect from either Heliolites or Plasmopora; 
 and as regards the smaller corallites, the condition of parts 
 is very similar to that which we have seen to exist in the 
 latter genus. I have not had the opportunity of examining 
 very young specimens of Propora tubulata-, but if we look 
 at a thin longitudinal section of an adult example (PI. XI., 
 % 3 ^) we see that the interspaces between the larger coral- 
 lites are occupied by a vesicular tissue, composed of lenticular 
 vesicles of different sizes, closely resembling the vesicular tissue 
 of a Cystiphyllum in general aspect. This tissue resembles that 
 of Plasmopora, except that the vesicles are more regular in form ; 
 and I entertain no doubt but that it is similarly formed by the 
 lateral anastomosis and confluence of the convex tabulae of the 
 interstitial tubes or small corallites, with the resulting oblitera- 
 tion of their walls. The walls of the small corallites, in fact, 
 can occasionally be very partially detected, though more usually 
 they have entirely disappeared as distinct structures. Similarly, 
 when we come to examine thin tangential sections of Propora 
 (PI. XI., figs. 3 and 3 a), we see that the narrow interspaces 
 between the comparatively close-set large corallites are occu- 
 pied by rows of irregular spaces, bounded by dark lines. 
 These lines, however, are not " costae," but are the cut edges 
 of the lenticular vesicles formed by the coalescence of the 
 curved tabulae with the walls of the small corallites. Ordin- 
 arily there is but a single row of small corallites between each 
 pair of large ones, though sometimes two rows are present. 
 (In long sections, as in PI. XI., fig. 3 b, there commonly 
 appears to be quite a wide tract of vesicular tissue between 
 two contiguous large tubes ; but this, of course, is only due 
 
THECID^E AND HELIOPORIDJE. 249 
 
 to the fact that the section has happened here to traverse 
 a line lying between several of the larger corallites.) 
 
 Accepting the above views as to the true structure of the 
 corallum of Propora, it seems clear that the genus agrees in 
 substantial characters with Plasmopora, with which therefore 
 it should be united. The species which have been referred 
 here are Upper Silurian in their range. (The supposed Car- 
 boniferous species is a Palaacis.) 
 
 Genus LYELLIA, Edwards and Haime, 1851. 
 
 (Pol. Foss. des Terr. Pal., p. 226.) 
 
 (PL XL, figs. 4, 4 a.) 
 
 Gen. Char. " Corallum massive ; corallites cylindrical, with 
 thick and costulated walls, free towards their terminations, and 
 united throughout the remainder of their length by a very 
 abundant vesicular ccenenchyma ; visceral chambers traversed 
 by somewhat irregular tabulae ; septa twelve in number, well 
 developed " (Edwards and Haime, loc. cit.) 
 
 Obs. The genus Lyellia was founded by Edwards and 
 Haime to include two species of corals (L. Americana and 
 L. glabra) from the Upper Silurian of North America. Other 
 species of the genus have been described by Dr Rominger 
 (Foss. Cor. of Michigan, p. 14), from deposits of the same 
 age ; and it is probable that some of the forms of Heliolites 
 (e.g., H. affinis and H. speciosus] described by Mr Billings 
 from the Lower and Upper Silurian deposits of Anticosti, 
 are really referable to Lyellia (Cat. Sil. Foss. of Anticosti, 
 pp. 5 and 30). I have not myself been so fortunate as to 
 meet with any examples of this genus, and am therefore 
 able to say nothing as to its minute internal structure. 
 Judging from the descriptions and figures of the above- 
 mentioned authors, Lyellia would seem to be nearly allied 
 to Plasmopora, and especially to those forms of the genus 
 which have been usually separated under the name of Pro- 
 
250 TABULATE CORALS. 
 
 pora. The conversion of the smaller corallites into a mass 
 of lenticular vesicles, and the round form of the larger coral- 
 lites (PI. XI., fig. 4 #), render this resemblance especially 
 noticeable. The large corallites, however, appear to be more 
 markedly free towards their upper ends, and the openings 
 of the smaller tubes upon the surface do not appear to be 
 conspicuous or even recognisable (PI. XL, fig. 4). 
 
 Dr Rominger, in his diagnosis of the genus, adds the 
 further character that the septa are composed of " vertical 
 rows of spinules." This of itself would go far to separate 
 the genus from Plasmopora and Heliolites, in which the septa 
 appear to be always lamellar. 
 
 Genus PINACOPORA, Nich. and Eth., jun., 1878. 
 
 (Mon. Sil. Foss. of Girvan, Fasc. i., p. 52.) 
 
 (PL XII., figs. 3 - 3 ft) 
 
 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 (' ccenenchymal 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 circular or oval in shape ; 
 small tubes irregular in shape. No mural pores. No colu- 
 mella." 
 
 Obs. The above generic diagnosis is taken from the Mono^- 
 
THECID^E AND HELIOPORID^E. 251 
 
 graph of the Silurian Fossils of Girvan (Fasc. I.), by Mr R. 
 Etheridge, jun., and myself, in which the only known species of 
 the genus viz., P. Grayi, of the Upper Silurian rocks of Ayr- 
 shire is fully described. As I have no further material of this 
 species in my hands, I shall content myself on the present occa- 
 sion with the following brief remarks, most of which are taken 
 from the work just alluded to. 
 
 The corallum in Pinacopora is free, and has the form of a 
 thin circular expansion, the under surface of which is covered 
 with a concentrically-striated epitheca (PI. XII., fig. 3). The 
 epitheca is always symmetrically concave, and its upper convex 
 surface (PI. XII., fig. 3 a) carries the corallites, which are re- 
 markable for their extreme shortness, when we take into 
 account 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 divided into two groups, the 
 relations of which to each other are remarkably uniform. The 
 larger corallites are arranged upon the upper surface of the 
 epitheca with great regularity in obliquely intersecting rows, 
 each individual tube being isolated and separated from its 
 fellows by a zone of the smaller tubes (PI. XII., fig. 3 b). 
 Usually but one single row of the small corallites intervenes 
 between any given pair of the larger tubes, but occasionally 
 and here and there a few extra interstitial tubes may be 
 developed. The large corallites, except in their extreme 
 shortness, are constructed upon the type of the correspond- 
 ing tubes in Heliolites and its allies, the resemblance between 
 the two being especially manifest in the presence in each of 
 twelve short septa (PI. XII., fig. 3 d). As in Heliolites, the 
 smaller corallites are wholly destitute of septa. Considering 
 the very limited vertical development of the corallites, the 
 tabulae may be said to be well developed, and they differ 
 in their arrangement in the large and small tubes respec- 
 tively. In the former, the tabulae (PI. XII., figs. 3 c and 
 3 e) are confined to the bottom of the visceral chamber, 
 
252 TABULATE CORALS. 
 
 and there is generally but one of these structures present, 
 though two or three may be developed, in which case they 
 are very closely approximated. In the smaller corallites the 
 tabulse are more numerous (PI. XII., fig. 3 e), and they extend 
 to close upon the summit of the tubes. No traces, lastly, of 
 mural pores, or of any other apertures, in the well-developed 
 walls of either the larger or smaller corallites have hitherto 
 been detected. 
 
 As regards the systematic position of Pinacopora, there can 
 be no doubt that it belongs to the family of the Helioporidcz, 
 and that its nearest relationships are with Heliolites itself. It 
 agrees with Heliolites in the essential structure of the large 
 corallites, and also in the more important features exhibited by 
 the small tubes. The latter, it is true, in their comparatively 
 limited development, remind us of Plasmopora (Propora) tubu- 
 lata, E. and H., the regular distribution of the large corallites 
 being another feature of resemblance between the type just 
 mentioned and the present form. On the other hand, there is 
 the fundamental difference that the walls of the small corallites 
 in Pinacopora are completely differentiated, while their tabulae 
 do not become vesicular. In these features, Pinacopora agrees 
 with Heliolites, from which it differs in the fact that the cor- 
 allum constitutes a thin, concavo-convex, leaf-like plate, not 
 attached to foreign bodies ; in the extraordinary shortness of 
 the corallites ; in the comparatively rudimentary condition of 
 the septa ; in the very regular arrangement of the large coral- 
 lites ; and in the peculiar arrangement of the tabulse in the 
 large and small tubes respectively. As before remarked, the 
 only described species of this genus is found in deposits of the 
 age of the Upper Silurian, in Ayrshire. 
 
253 
 
 CHAPTER XII. 
 
 AND MONTICULIPORID.E. 
 
 USING the n'ame Chcetetidce in the wide and general sense in 
 which it has been usually employed, and temporarily including 
 under this title the genus Monticulipora and its allies, we 
 find that the group now under discussion comprises massive, 
 ramose, laminar, or encrusting corals composed of contiguous 
 tubular corallites, which are intersected by complete tabulae, 
 and are destitute of mural pores. There are either no struc- 
 tures of the nature of septa, or, at most, mere rudiments of 
 such. All the corallites may be like one another, or the 
 corallum may be composed of two distinct and differing sets 
 of tubes. 
 
 The Chcetetidce were regarded by Milne -Edwards and 
 Haime as a " tribe " of the Favositidce, and the genera Chcetetes, 
 Fischer, Dania, E. and H., Stencpora, Lonsd., and Constellaria, 
 Dana, were regarded as constituting this division (Brit. Foss. 
 Cor. Introduction, p. Ixi, 1850). Monticulipora, D'Orb., was 
 originally included by Edwards and Haime under Chcetetes, 
 but they subsequently admitted its generic distinctness (Brit. 
 Foss. Cor., p. 264, Note, 1854). The genus Fistulipora, 
 M'Coy, on the other hand, was placed by the French observers 
 in the family of the Milleporidce, in the immediate neighbour- 
 hood of Heliolites. In their great work, the ' Polypiers 
 Fossiles des Terrains Palaeozoiques,' Milne - Edwards and 
 Haime established the three additional genera Beaumontia, 
 Dekayia, and Labechia, which they placed in the Chcetetince i 
 
254 TABULATE CORALS. 
 
 and in his last important work upon the corals (Hist. Nat des 
 Cor., 1860), M. Milne-Edwards adhered substantially to the 
 above arrangement, except that Stenopora, Lonsd., is now not 
 regarded as a well-characterised type. 
 
 In the sense in which it is here employed, the family 
 Chcetetidce corresponds in the main with the " tribe " Cluetetince 
 of Edwards and Haime. Stenopora, Lonsd., is, however, now 
 placed among the Favositida; Labechia, E. and H., is regarded 
 as the type of a special group ; and Fistulipora, M'Coy, and 
 Prasopora, Nich. and Eth., jun., are temporarily added to the 
 family, to take their proper place beside Monticulipora. Thus 
 constituted, it must be at once admitted that the family is an 
 artificial and unnatural assemblage, the retention of which, as a 
 single group, can only be defended upon the ground of our at 
 present imperfect knowledge of the structure and real relations 
 of many of the forms included in it. It is clear, indeed, that 
 the forms here provisionally associated under the family 
 Chatetida agree with one another only in the general fact that 
 they possess coralla composed of closely contiguous corallites, 
 which are without septa, are traversed by tabulae, and have 
 imperforate walls. This last character, however, cannot be 
 regarded as sufficiently established for all the forms now under 
 consideration. Some of them almost certainly possess noth- 
 ing of the nature of the " mural pores " of the Favositida, and 
 none of them have been actually proved to possess openings 
 of a similar nature to the above. It is not impossible, how- 
 ever, that some of the genera at present placed in the Chatetidce 
 may yet be demonstrated to possess " mural pores ; " and I 
 have myself examined a coral from the Wenlock Limestone of 
 Dudley, which is closely similar to Monticulipora, D'Orb., in 
 form and general appearance, but in which the walls are in- 
 dubitably porous. Moreover, an examination of the minute 
 structure of the forms here included under the Chcetetida 
 renders it clear that they admit of separation into two groups, 
 of very different size, and perhaps of a very different nature. 
 In the one group which we may speak of as the 
 
 \\ 
 
 -*. , 
 \ 
 
CHMTETID& AND MONTICULIPORID^E. 255 
 
 proper we have only the forms which properly constitute the 
 genus CJuztetes, Fischer (as typified by C. radians, Fisch., and 
 exclusive of the Monticuliporce). These forms possess corallites 
 of one kind only, which are completely amalgamated by their 
 walls, and which possess comparatively few and remote tabulae. 
 In the other group we have all the forms included under the 
 genera Monticulipora, D'Orb., Fistiilipora, M'Coy, Dekayia, 
 E. and H., Const ellaria, Dana, and Prasopora, Nich. and Eth., 
 jun., in all of which the walls of the corallites are not fused 
 with one another, and there is mostly the important feature 
 that the corallum is composed of two distinct classes of coral- 
 lites, indicating the existence during life of two distinct kinds 
 of zooids. The corals of this latter group I shall speak of 
 collectively as the Monticuliporida, though I do not at present 
 feel justified in finally removing them from the vicinity of the 
 Chcztetidce proper, as there are a few forms generally referred 
 to Monticulipora in which the corallites are homomorphic, and 
 in which the corallum only differs from that of Chcetetes^ in its 
 most restricted sense, in the fact that the corallites are not 
 united by their walls. 
 
 As regards the affinities of the Chcetetidce and Monticuli- 
 poridce anything that can be said at the present moment can 
 be regarded as, at best, little more than conjecture. So far as 
 Ch&tetes proper is concerned, I do not at present see that we 
 have any sufficient ground for supposing that we have to deal 
 in it with anything but a group of genuine -Actinozoa. The 
 association of Chcetetes with the true Favositida, as proposed by 
 Milne- Ed wards and Haime, must certainly be rejected, as there 
 is no evidence to hand of the existence of perforations in the 
 walls of the former, and there are other important differences as 
 well. At the same time, the general structure of Chcetetes is 
 entirely that of the Corals rather than of the Polyzoa, and there 
 is a very close resemblance to such forms as Tetradium, Saff,, 
 the only essential difference between these two types being the 
 possession by the latter of definite septa. When, however, 
 we come to ask more particularly as to the precise place of 
 
256 TABULATE CORALS. 
 
 Chcztetes among the Actinozoa, it becomes abundantly clear 
 that we have no sufficient data upon which to found a final 
 conclusion. All that can be said is that the genus seems to 
 have nearer relationships with the Halysitidce and Tetradiida 
 among the Palaeozoic " Tabulata " than with any others, and 
 that we may therefore suppose, with some probability, that it is 
 really an ancient type of the Alcyonaria. 
 
 Still greater difficulties surround the attempt to definitely 
 fix the place of the Monticuliporidce in the zoological system. 
 Within late years there has been a strong tendency among 
 palaeontologists to relegate the fossils in question to the Polyzoa, 
 and a good deal of evidence some of which will be referred to 
 subsequently has been brought forward in support of this 
 view (see especially the admirable paper by Dr Lindstrom on 
 the affinities of the Anthozoa Tabulata in the ' Annals of 
 Natural History,' 1876). The chief ground for the proposal 
 to refer Monticulipora and its allies to the Polyzoa is found in 
 the resemblance between the ramose Monticulipora and the 
 Polyzoan genus Heteropora, De Blainv., and it must be ad- 
 mitted that the mere general likeness between these two types 
 is extremely close. External similarity, however, is an unsafe 
 guide in dealing with questions of zoological affinity, and such 
 evidence as I have at present in my hands leads me to believe 
 that there is in reality no relationship beween Monticulipora 
 and Heteropora. The latter of these types is best known as 
 occurring in the Tertiary deposits as a fossil, but I possess a 
 large and well-marked recent form from New Zealand, nearly 
 allied to H. pustulosa, Busk, and H. tortilis, Lonsd., which I 
 have submitted to Mr Busk, and which this eminent authority 
 has pronounced to be new. In this interesting species, as in 
 the extinct forms of the genus, the polyzoary is ramose and 
 calcareous (fig. 34), and consists of long, tubular, thin-walled 
 cells, which radiate from the imaginary axis of the branches to 
 open on the surface by round apertures. The walls of the cells 
 appear to be imperforate, though in some forms of the genus 
 (H. l&vigata, D'Orb.) they are pierced by minute foramina ; 
 
CHsETETID.l AND MONTICULIPOlUDsE. 257 
 
 nor are any traces of transverse partitions or " tabulae " to be 
 detected. Between the true cells, and more or less completely 
 separating them from one another, are numerous smaller " in- 
 
 Fig. 34. A, Fragment of an undescribed living species of Heteropora, from New Zealand, of 
 the natural size ; and B, Surface of the same, enlarged (original) ; c, Surface of a branch 
 of Heteropora snbreticulata, from the Tertiary, enlarged (after Reuss). 
 
 terstitial tubes," which in this particular form appear to have 
 their mouths unrestricted by any partial diaphragm, and which 
 nearly equal the true cells in point of size. It is the presence 
 of these interstitial tubes which gives to Heteropora its very 
 close superficial resemblance to the ramose species of Monti- 
 culipora and Fistulipora. Not only is the nature of these 
 tubuli still obscure, but they present the curious feature that 
 they exhibit (in some cases at any rate) structures which, to 
 say the least of it, admit of comparison with the " tabulae " of 
 Monticulipora. Many or all, namely, of the mouths of the 
 " interstitial tubes " of some species of Heteropora are closed 
 by a delicate transverse partition or lid, which is perforated in 
 its centre by a small aperture, and is placed a little below the 
 lip of the opening. Sometimes these " hymen-like lids," as 
 shown by Prof. Busk, are periodically produced at successive 
 stages of growth, and thus come to simulate " tabulae." In 
 Heteropora clavata, Goldf., the same distinguished observer has 
 also shown that the mouths of the interstitial tubes commonly 
 exhibit a stellate appearance, owing to the projection into their 
 interior of delicate vertical lamellae, which simulate the " septa " 
 of the true corals. 
 
 R 
 
258 TABULATE CORALS. 
 
 When we consider the structural characters of Heteropora, 
 as above briefly indicated, it cannot be denied that there is a 
 general resemblance between this type and the ancient Monti- 
 culipora and Fistulipora. Dr Lindstrom, in the memoir already 
 referred to, has further brought forward a considerable body of 
 evidence, which I shall more fully allude to hereafter, to prove 
 that the developmental history of Monticulipora shows it to be 
 a Polyzoon. In the meanwhile, however, I am unable to admit 
 that we have sufficient evidence for the removal of Monticuli- 
 pora and its allies from the Actinozoa, and their transference 
 to the Polysoa. So far as Heteropora is concerned, the genus 
 seems to be sufficiently separated from Monticulipora by its 
 total absence of genuine tabulae in the cells themselves and its 
 (occasionally) perforated walls, together with the occurrence in 
 some forms of radiating septa in the interstitial tubes. On 
 the other hand, Monticulipora presents the closest possible 
 resemblance in most of its structural features to the ramose 
 Favositidtz, from which it can only be separated by the general 
 possession of two sets of corallites and the apparent absence 
 of mural pores. That the latter are true Actinozoa does not, 
 in my opinion, admit of doubt, and I think we must in the 
 meanwhile come to the same conclusion as regards Monticuli- 
 pora itself and the closely-allied Fistulipora, Constellaria, and 
 Prasopora. The three last of these types, and the great 
 majority of the forms usually included under the first name, 
 possess a corallum which is composed of two distinct sets of 
 corallites, a feature which at once reminds us of the Helio- 
 porida, and would lead us to suppose that the MonticuliporicUz 
 are to be regarded as an ancient group of Alcyonaria. More- 
 over, the different sets of corallites in these forms are not only 
 unlike in point of size, but the smaller tubes are almost in- 
 variably more closely tabulate than the larger tubes, this being 
 another feature in which they unmistakably approach the 
 Helioporidce. In no known forms of Polyzoa, not even in 
 Heteropora, can a similar condition of parts be shown to exist, 
 and I am therefore of opinion that we are not justified, with 
 
CH^TETIDJE. AND MONTICULIPORID^E. 259 
 
 the evidence now before us, in removing the MonticuliporidfZ 
 from the Actinozoa, and that we may provisionally regard them 
 as a special group of Alcyonaria. It should also be borne 
 in mind in this connection that we are at present quite un- 
 acquainted with the animal of Heteropora, and that it is just 
 possible that an examination of the soft parts of this type 
 admittedly a very aberrant form of the Polyzoa might 
 show it to be a Ccelenterate. At the same time, I do not at all 
 mean to deny but that some of the fossils which have been 
 described by various palaeontologists under the names of Mon- 
 ticulipora, Fistulipora, or Callopora, are probably really Polyzoa. 
 Erroneous determinations of this kind, especially where micro- 
 scopic examination has not been resorted to, are almost inevit- 
 able ; but they do not affect the systematic position of the 
 forms which are recognised as the types of Monticulipora and 
 of the genera related to this. 
 
CHAPTER XIII. 
 
 GENERA OF CH/ETETID^ AND MONTICULIPORID^E. 
 
 Genus CH.ETETES, Fischer, 1837.. 
 (Oryct. de Gouv. de Moscou, p. 159.) 
 
 Gen. Char. Corallum massive, composed of long irregu- 
 larly prismatic erect corallites, which are closely contiguous, and 
 are completely amalgamated by means of their walls. Coral- 
 lites of one kind only, opening upon the surface by means of 
 irregularly polygonal, non-oblique calices, and destitute of true 
 septa. Walls imperforate. Tabulse complete, comparatively 
 remote, often placed at corresponding levels in contiguous 
 tubes. Visceral chamber often partially divided by an imper- 
 fect longitudinal septum (or by two such septa) resulting from 
 the uncompleted fission of the tube into two young corallites. 
 
 Obs. It is not necessary to enter here into a detailed ac- 
 count of the genus Chcetetes, except in so far as concerns its 
 relations with the genera Stenopora, Lonsd., and Monticulipora, 
 D'Orb., and even on this point little need be said. The type 
 of the genus Chcztetes is unquestionably the great C. radians, 
 Fischer, of the Carboniferous Limestone of Russia, and the 
 characters of the genus must, therefore, necessarily be based 
 upon this species. This form was for the first time adequately 
 
GENERA OF CH^ETETIDM AND MONTICULIPORID^E. 261 
 
 described by Mr Lonsdale (Geol. of Russ., vol. i. p. 595, 1845), 
 who drew special attention to the fact that the walls of the 
 corallites are inseparably united, so that fractures expose the 
 interior of the tubes, this structure depending upon the fissi- 
 parous mode of increase of the coral. M'Coy (Brit. Pal. Foss., 
 p. 82, 1851) may be considered as entirely accepting Mr Lons- 
 dale's views as to the characters of the genus Chcetetes. Milne- 
 Edwards and Haime (Brit. Foss. Cor. Intr., p. 61, 1850), while 
 accepting the genus, ignore the feature just alluded to as so 
 strongly emphasised by Mr Lonsdale, and add no character 
 which could be accepted as in any way of generic value. In 
 the " Polypiers Fossiles" (p. 261, 1851) the same authors give 
 a fuller account of Chcztetes, and they now unite with it the 
 genus Stenopora, Lonsd., and also the ill-characterised type 
 which D'Orbigny had named Monticulipora (Prodr. de Pal^ont, 
 t. i. p. 25, 1850). At a still later period (Brit. Foss. Cor., p. 
 264, 1854), the two distinguished French observers so far 
 altered their views that they accepted Monticulipora, D'Orb., 
 as distinct from Chcetetes, Fischer, the ground of distinction 
 being that in the former the corallum increases by gemmation, 
 whereas in the latter the mode of growth is by fission. Most 
 subsequent writers have followed the course ultimately adopted 
 by Milne-Edwards and Haime, so far as concerns the generic 
 distinctness of Chatetes and Monticulipora, and the grounds 
 of this distinction. In a paper, however, upon the species of 
 Ch<ztetes in the Lower Silurian rocks of North America 
 (Quart. Journ. Geol. Soc., vol. xxx. p. 499, 1874), I formerly 
 expressed the opinion that the genera Ch&tetes and Monticuli- 
 pora were not sufficiently differentiated, and that the mere 
 mode of growth, even if admitted to be of generic value, was a 
 character so difficult, in many instances, of determination, that 
 it should not be regarded as of itself sufficient to separate two 
 types otherwise closely allied. At the same time I stated that 
 I thought Stenopora, Lonsdale, to be insufficiently character- 
 ised, and pointed out that different observers had defined this 
 genus by means of very different and in some cases compara- 
 
262 TABULATE CORALS. 
 
 tively trivial features. To the opinions expressed in the paper 
 just referred to I still adhere in the sense, that is, that I still 
 think the conclusion which I had then reached the only one 
 justified by the information at that time published. Since that 
 time, however, I have had the opportunity of making a careful 
 microscopic examination of authentic Russian specimens of C. 
 radians ; Fischer, the type of its genus, and I am now quite 
 satisfied as to its generic distinctness ; while a similarly minute 
 investigation of Monticulipora and its allies has convinced me 
 that here also we have to deal with a distinct generic type. 
 Lastly, as has been previously shown, I have had now the op- 
 portunity, in association with my friend Mr R. Etheridge, jun., 
 of examining authentic Australian specimens of Stenopora, 
 Lonsd., and have thus been able to show that this genus is one 
 quite distinct from either Chcetetes or Monticulipora^ and, in 
 reality, referable to the Perforate group of the Favositidce. 
 
 The type, then, of the genus Chcetetes, as here restricted, is 
 the C. radians, Fischer, of the Carboniferous of Russia, and the 
 generic diagnosis previously given is founded upon an exami- 
 nation of the structural characters of this form. It has, how- 
 ever, been pointed out by Mr R. Etheridge, jun., and myself 
 (Journ. Linn. Soc., vol. xiii. p. 365, 1877) that the corals known 
 as Alveolites septosa, Flem., and A. depressa, Flem., are generi- 
 cally inseparable from Chcetetes radians, Fischer ; and we have 
 further described another species (Chcetetes hyperboreus), from 
 the Carboniferous rocks of Scotland, as possessing similar 
 generic characters. All the forms just mentioned are of Car- 
 boniferous age, and there are no published species of corals from 
 either older or younger deposits which can, in the meanwhile, 
 be certainly asserted to belong to the same genus. I may say, 
 however, that I have collected in the Devonian Limestone of 
 Gerolstein, in the Eifel, specimens of a coral which would ap- 
 pear to be congeneric with C. radians, Fischer. 
 
 If we take the corals just mentioned as the only satisfactorily 
 identified species of Chcetetes, we find that the corallum is mas- 
 sive and usually irregularly hemispherical or pyriform in shape, 
 
GENERA OF CH^ETETID.E AND MONTICULIPORIDsE. 263 
 
 rarely (C. hyperboreus, Nich. and Eth., jun.) forming thin flat- 
 tened expansions, with a concentrically-striated epitheca below. 
 The corallites are irregularly polygonal, and are in complete 
 contact throughout their entire length. Rough fractures (gen- 
 erally, but not always) expose the interior of the tubes ; and 
 thin sections, whether transverse or longitudinal (PI. XII., figs. 
 4, 4 a, 4 d}, show that the walls of contiguous corallites are 
 entirely and undistinguishably amalgamated or fused with one 
 another, the originally duplex character of the partition between 
 neighbouring corallites being in no case recognisable. Though 
 somewhat variable in shape and size, the corallites are indubi- 
 tably of one kind only, and there is no reason for believing that 
 the corallum consisted of two distinct sets of zooids. The 
 corallites, further, are not reclined, as in the typical species of 
 Alveolites, Lam., but are erect, in precisely the sense that this 
 term is employed in speaking of the massive coralla of species 
 of Favosites, such as F. Gothlandica, Lam., and its allies. The 
 calices, therefore, though wanting the regularly polygonal form 
 of those of Favosites, are never oblique or semilunar, with one 
 lip more prominent than the other, as is so characteristically 
 the case in Alveolites and its allies. The walls of the corallites 
 seem to be wholly imperforate, and as this conclusion is based 
 upon a minute examination of thin sections as well as of actual 
 specimens, its correctness may be accepted as tolerably certain. 
 This character, therefore, alone is sufficient to separate Chcetetes 
 from all the externally similar genera of the Favositidce. No 
 traces whatever either of lamellar or of spiniform septa can be 
 detected in thin sections or in the specimens themselves (except 
 some obscure longitudinal striae in C. septosus], and these struc- 
 tures must therefore be considered as wholly wanting. There 
 exists, however, in a certain number of the corallites a curious in- 
 ward projection of the wall (PI. XII., figs. 4, 4.6), which is seen 
 both in typical specimens of C. radians, Fischer, and also in C. 
 hyperboreus, Nich. and Eth., jun., C. (Alveolites] septosus, Flem., 
 and C. (Alveolites] depressus, Flem. In the two last-mentioned 
 species this inward process was noticed and figured by Edwards 
 
264 TABULATE CORALS. 
 
 and Haime, and they regarded it as being a " septal tooth," 
 similar to the unpaired septal ridge of certain species of Alveo- 
 lites. As pointed out by Mr R. Etheridge, jun., and myself, 
 however (Journ. Linn. Soc., vol. xiii. p. 366), this supposed 
 septal tooth was more correctly interpreted by Mr Lonsdale 
 (Geol. Russ. and Ural, vol. i. p. 95), who regarded it as being 
 an inflection of the wall of the corallite, due to its undergoing 
 the process of division by fission into two tubes. That this 
 view is the correct one is shown by the fact that this inwardly- 
 projecting ridge is of variable length and of equally variable 
 occurrence. It is never present in more than a quite limited 
 number of the tubes, and it varies in size from a hardly per- 
 ceptible protuberance up to a vertical lamina extending half- 
 way or more across the tube, while it is not uncommonly faced 
 by a corresponding ridge upon the opposite side of the vis- 
 ceral chamber. Lastly, the tab^llce in Chatetes are always well 
 developed, and are invariably complete and horizontal. Mr 
 Lonsdale considered that the tabulae of Chcetetes were placed 
 at corresponding and remote levels, and separated by zones 
 in which no tabulae were developed, but Milne-Edwards and 
 Haime explicitly deny this (Pol. Foss. des Terr. Pal., p. 261). 
 So far as Ch&tetes radians, Fischer, is concerned, the truth 
 seems to lie between these two extremes, for the tabulae are 
 certainly developed throughout the entire course of the coral- 
 lites at comparatively remote intervals (PI. XII., fig. 4 a) ; but 
 they are, at the same time, periodically developed at corre- 
 sponding levels at certain horizons, so that the corallum as a 
 whole readily splits into a series of concentric layers. In the 
 other species here included in the genus the tabulae appear to 
 be developed more irregularly, though they are always present. 
 As regards the zoological affinities of Chcztetes> it is not pos- 
 sible at present to reach any final conclusion. In spite of the 
 resemblance of the corallum of Ch&tetes to that of some forms 
 of Favosites (such as F. Bowerbanki, E. and H., sp.), it is quite 
 clear that there is no direct relationship between these two 
 types, if we admit that the former possesses imperforate walls, 
 
GENERA OF CH^ETETID^E AND MONTICULIPORIDsE. 265 
 
 as seems all but absolutely certain. At the same time, I see 
 no reason whatever for accepting the view, advocated at the 
 present day by high authorities, that Chcetetes is not truly a 
 Ccelenterate. I am quite unable to recognise in the structure 
 of the fossils referred to this genus anything which would 
 justify us in referring them to the Polyzoa (as advocated by 
 Lindstrom and others), and I think the general details of their 
 structure to be such as are only compatible with their being 
 members of the Coslenterata. The precise position which they 
 should occupy among the Actinozoa is a point upon which it 
 is far more difficult to arrive at any positive conviction. Upon 
 this point, while confessing the absence of positive evidence, I 
 can only say that I am disposed to agree with Professor Martin 
 Duncan (Third Rep. on Brit. Foss. Cor. ; Brit. Ass. Reports, 
 1871, p. 128) in thinking that Chcetetes is probably an Alcy- 
 onarian. 
 
 As to the relations of Chcetetes to allied genera, it can only 
 be said at present that there is nothing save close external 
 resemblance to unite the genus with any other, and especially 
 with the group of which Monticulipora is the central type. 
 For reasons previously given, I have not thought myself 
 justified in definitely separating the species of the latter from 
 Chcetetes, with which they often agree in general form and habit, 
 as well as in the imperforate walls of their corallites ; but I 
 entertain at the same time a strong conviction that there 
 is little or no true affinity between the two. Most of the 
 so-called Monticulipora^ apart from other peculiarities, have 
 heteromorphic coralla, composed of two distinct sets of 
 zooids, and in all of them the walls of the corallites are 
 not amalgamated with one another. These distinctions alone 
 are quite sufficient to fundamentally separate the typical forms 
 of Monticulipora from Chcetetes. The type with which Chcztetes 
 shows the strongest affinity is the Silurian Tetradiumi but in 
 this genus we have well -developed and definitely-disposed 
 lamellar septa, and we can therefore hardly suppose that 
 the two genera are closely related. 
 
266 TABULATE CORALS. 
 
 The species of Chcetetes, as here defined, are not known to 
 occur out of the Carboniferous (and possibly the Devonian) 
 rocks ; and I shall give a brief description of the type- 
 species, C. radians, Fischer, founded upon an examination 
 of specimens derived from the Carboniferous Limestone of 
 Russia and the north of England. 
 
 Chsetetes radians, Fischer. 
 (PI. XIL, figs. 4, 4 d.) 
 
 Chcetetes radians, Fischer, Oryct. de Moscou, p. 160, PI. XXXVI., fig. 3, 1830. 
 radians, Lonsdale, Russ. and Ural, vol. i. p. 595, PI. A, fig. 9, 1845. 
 radians, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 263, 
 
 PI. XX., figs. 4, 4 a, 1851. 
 radians, Milne-Edwards and Haime, Brit. Foss. Cor., p. 158, 1852. 
 
 Spec. Char. Corallum massive, of large size, composed of 
 long basaltiform, closely contiguous corallites, which are inti- 
 mately united by their walls. Calices irregularly polygonal, 
 often elongated, being in the former case about a fourth of a 
 line in diameter on an average, whereas in the latter case they 
 are about one-fifth of a line or less in their short diameter, and 
 one-third of a line in their long diameter. Walls imperforate. 
 Septa wanting. Visceral chamber commonly partially divided 
 by an imperfect longitudinal partition on one side, which ap- 
 pears in the calice as a tooth-like process, and which is some- 
 times confronted by a similar process proceeding from the 
 opposite wall of the tube. The tabulae are complete, well 
 developed, variable in number, sometimes about a quarter of 
 a line apart, sometimes much more remote, and often specially 
 developed along planes concentric with the surface, so that the 
 corallum splits into a succession of concentric layers or zones. 
 
 Obs. The Russian examples of this species which I have 
 had the opportunity of examining form large masses of a 
 pyriform shape, six inches or more in height, and composed 
 of long basaltiform tubes which are in complete contact 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 267 
 
 throughout, and which, though somewhat unequal in point 
 of size, are not divisible into a series of larger and smaller 
 corallites. Transverse and longitudinal microscopic sections 
 (PI. XII., figs. 4 and 4 a) show that the walls of contiguous 
 corallites are absolutely and uniformly amalgamated, so that 
 no traces whatever can be detected of the original divisional 
 lines between them. The walls are thick, and the most care- 
 ful examination both of actual specimens and of thin sections 
 has failed to produce any evidence of the existence of mural 
 pores ; so that we must accept the view held by all the older 
 observers of this species as to the imperforate condition of the 
 walls of the corallites. The calices, like the corallites, are un- 
 equal in point of size, though in no uniform manner, and com- 
 monly exhibit an inward tooth-like projection (PI. XII., fig. 4 b] 
 on one side, sometimes with a similar but smaller correspond- 
 ing process on the opposite side of the tube. These tooth- 
 like projections are never present in more than a quite limited 
 number of the tubes, and they vary much in length ; while 
 transverse sections (PI. XII., fig. 4) show them to be pro- 
 duced by the existence of a vertical lamella or longitudinal 
 inflection of the wall of the corallite. Their true nature was 
 pointed out by Lonsdale (loc. cit.}, who maintained that they 
 were due to the uncompleted fission of the old tubes, the fissi- 
 parous mode of development being characteristic of the species. 
 The correctness of the views of Mr Lonsdale upon this point 
 has subsequently been upheld by Mr R. Etheridge, jun., and 
 myself (Journ. Linn. Soc., vol. xiii. p. 366). The tabular 
 (PI. XII., fig. 4 a) are always numerous, and are invariably 
 complete and horizontal ; and Milne-Edwards and Haime are 
 perfectly right in asserting (in their description of the genus 
 Chcetetes} that they are not uniformly placed at corresponding 
 levels in contiguous tubes. At the same time Mr Lonsdale is 
 correct in his assertion that the species possesses " diaphragms 
 in parallel bands ; " for the tabulae are specially developed peri- 
 odically, at the same level in all the tubes, so that the corallum 
 is conspicuously composed of a succession of concentrically dis- 
 
2 68 TABULATE CORALS. 
 
 posed strata, which generally have a thickness of from half an 
 inch to three-quarters of an inch. 
 
 In addition to specimens from the Carboniferous Limestone 
 of Moscow, I have examined a number of examples which I 
 have collected from the Carboniferous Limestone of the north 
 of England a formation from which C. radians is quoted by 
 Milne-Edwards and Haime. The British specimens entirely 
 resemble the Russian ones in their shape and general configu- 
 ration, in their long basaltiform corallites, and in the composi- 
 tion of the corallum out of concentrically disposed strata formed 
 by a periodic development of tabulse at corresponding levels. 
 At the same time there are some differences between the two 
 sets of specimens. The English examples (PI. XII., figs. 4 c 
 and 4 d] have rather smaller tubes, which are more regularly 
 polygonal, and more uniform in shape, and which are slightly 
 more thin-walled than is the case in Russian specimens. The 
 tabulae also are not nearly so numerous, and few of these struc- 
 tures are developed between the concentric zones of these 
 diaphragms, by which the whole colony is divided into super- 
 imposed strata. At the same time, there is the same total 
 amalgamation of the walls of the corallites, and in certain of 
 the tubes we always see the same tooth-like projection indicat- 
 ing the approaching division of the corallite into two. Upon 
 the whole, therefore, in spite of the differences just noted, I am 
 not disposed to regard the British specimens as more than a 
 mere variety of the typical C. radians of Russia. 
 
 As has been already pointed out, C. radians, Fischer, is 
 closely allied to C. (Alveolites) septosits, Flem., C. (Alveolites] 
 depressus, Flem., and C. hyperboreus, Nich. and Eth., jun., with 
 which it forms a most natural group ; and all of these forms 
 are characteristic of the Carboniferous Limestone. The last 
 mentioned of these species is easily separated from C. radians 
 by the lamellar and expanded form of the corallum, as well as 
 by other characters, and C. depressus, Flem., is similarly separ- 
 able by the very small size of its tubes. On the other hand, 
 C. (Alveolites] septosns, Flem., so nearly approaches C. radians 
 
GENERA OF CH^ETETID^ AND MONTICULIPORIDAL. 269 
 
 in its leading characters, that the specific distinctness of the 
 two may well be called in question, but I am unable to offer 
 any definite opinion upon this subject till I may have been able 
 to examine the original specimens of the former species. All 
 that I can say now is, that such specimens as I have seen of 
 the British Carboniferous coral ordinarily called by the name 
 of C. septosus, or Alveolites septosa, seem to be very similar in 
 appearance and structure to C. radians, Fischer, though a 
 microscopic examination may yet show that they are distinct. 
 
 Formation and Locality. Carboniferous Limestone of Mos- 
 cow, Russia. Not uncommon in the Carboniferous Limestone 
 (" Orton Scar Limestone ") of Hardendale Nab, near Shap, 
 Westmorland, and in the same limestone at Penruddock, 
 Cumberland. (Quoted by Milne-Edward and Haime from the 
 same horizon at Kendal, Westmorland.) 
 
 MONTICULIPORIM:. 
 
 Genus MONTICULIPORA, D'Orbigny, 1850. 
 (Prodr. de Paleont, t. i. p. 25.) 
 
 Nebulipora, M'Coy, Ann. Nat. Hist, ser. 2, vol. vi. p. 282, 1850. 
 Orbitulites, Eichwald, Zool. Spec., t. i. p. 180, 1829. 
 Orbipora, Eichwald, Leth. Rossica, t. i. p. 484, 1860. 
 Stenopora, M'Coy ? (non Lonsdale), Brit. Pal. Foss., p. 24, 1851. 
 
 Gen. Char. Corallum very variable in shape, massive, 
 ramose, laminar, frondescent, or encrusting, composed of nu- 
 merous tubular closely-approximated corallites, the walls of 
 which are not amalgamated with one another. Walls imper- 
 forate (so far as certainly known, though one or two forms 
 otherwise undistinguishable from the genus unquestionably 
 possess " mural pores "). Septa entirely wanting. Tabulae 
 always well developed, complete. Corallites usually distinctly 
 divisible into two series, one of large and the other of small 
 tubes, the latter usually more closely tabulate than the larger 
 ones, or otherwise differing from these in structure. Surface 
 
270 TABULATE CORALS. 
 
 commonly exhibiting at regular intervals definite areas occu- 
 pied by corallites which are larger or smaller than the average. 
 These areas are commonly elevated above the general surface, 
 and are then known as " monticules." 
 
 Obs. The corals which are usually known by the name of 
 Monticulipora, together with the forms allied to this, constitute 
 perhaps the most intricate and difficult assemblage of Palaeozoic 
 fossils with which the zoophytologist is called upon to deal. I 
 had originally intended to devote considerable space to this 
 group ; but I find that the limits of this work will not allow of 
 my carrying out this intention, and I have decided rather to 
 publish an entirely separate memoir upon the Monticuliporidce . 
 Here, therefore, I shall merely give a brief outline of the 
 general results of the investigations which I have been carrying 
 out as to the internal structure of the corals usually referred to 
 Monticulipora and allied types. 
 
 [It may not be out of place if I add a few remarks here as to the proper 
 method of making thin sections of the Montiatliporidce ; for the results which I 
 have obtained will certainly not be reached by other investigators, unless they 
 follow the plan of procedure which I have adopted. In any massive or ramose 
 Monticulipora (and, I may add, in any coral similarly composed of tubular 
 corallites radiating from an imaginary axis), the true structure can only be under- 
 stood by making three distinct sections. Two of these sections are perfectly 
 obvious and natural ones one being transverse, or at right angles to the long 
 axis of the corallum, while the other is vertical, and is taken in the median plane 
 of the corallum and parallel with its long axis. I used myself to consider these 
 two sections sufficient, and probably others have entertained a similar opinion. 
 Owing, however, to the fact that the diverging corallites often very materially 
 alter their character just before they open on the surface, and owing also to the 
 generally very limited inward extension of the interstitial small corallites (the 
 so-called " coenenchymal tubules "), as also of the curious intertubular spines 
 which are commonly present, it is absolutely necessary to make a third series 
 of sections which should run just below the calices of the corallites and at right 
 angles to the long axis of the latter. The direction in which it will be necessary 
 to cut any given coral to obtain sections of this nature will always vary with 
 the form of the corallum ; but these sections may be termed tangential, as they 
 must in all cases be taken in a direction tangential to the calicular surface and 
 just below that surface. Sections of this kind are most instructive and im- 
 portant ; and from my ignorance of their value and consequent neglect to pre- 
 pare them, I have fallen into grave errors, or failed to seize the true structure, 
 in the case of certain forms of this group, of which I have on former occasions 
 described the minute characters.] 
 
GENERA OF CH&TETIDJB, AND MONTICULIPORID^E. 271 
 
 The genus Monticulipora was founded by D'Orbigny in 
 1850 (Prodr. de Pal., t. i. p. 25, where the date of the genus is 
 given as 1847); the only definition being: "cellules serrees, 
 poriformes a la surface, d'un ensemble rameux ou encroutant 
 couvert de petites saillies coniques." The first species given 
 under this definition is the well - known M. mammulata, 
 D'Orbigny, of the Lower Silurian of the United States, which 
 must, therefore, be accepted as the type of the group. It will 
 be quite obvious that the only character in the above definition 
 which has the very remotest generic value, is the existence of 
 conical elevations or " monticules " upon the surface, and even 
 the nature of these elevations is left wholly undefined. The 
 genus Nebulipora, M'Coy (Ann. Nat. Hist, ser. 2, vol. vi. 
 p. 282, Oct. 1850) was founded in the same year as Monticuli- 
 pora, and includes forms unquestionably congeneric with the 
 latter, though I am unable from his figures and descriptions to 
 be sure as to the precise species upon which M'Coy founded 
 his genus. This point, indeed, could only be set at rest by an 
 examination of the original specimens in the Woodwardian 
 Museum, which I have unfortunately had no opportunity of 
 inspecting. It is, however, a matter which, I think, will still 
 admit of discussion, as to whether or not M 'Coy's Nebulipora 
 should not be adopted as the title for the fossils now under 
 consideration, rather than the Monticulipora of D'Orbigny. I 
 am not able to decide this point, and I will only remark, further, 
 that M'Coy, in his generic diagnosis, states that the walls of 
 Nebulipora are " apparently perforated by rows of small fora- 
 mina," though he does not allude to this character again, and 
 seems to have been doubtful as to its actual existence. The 
 typical Monticuliporce seem to be undoubtedly devoid of mural 
 pores ; but I have examined (through the kindness of my 
 friend Mr R. Etheridge, jun.) a specimen from the Wenlock 
 Limestone of Dudley in the collection of the British Museum, 
 which has all the external and general characters of such a Mon- 
 ticulipora as M. petropolitana, Pand., but in which the walls of 
 the corallites are unquestionably minutely porous. It is not 
 
272 TABULATE CORALS. 
 
 impossible, therefore, that it is upon some such specimen as 
 the preceding that M'Coy founded the statement that I have 
 referred to. 
 
 As regards the later history of Monticulipora, it is sufficient 
 to add here that Milne-Edwards and Haime at first placed all 
 the forms referred to this genus under C/uztetes (Pol. Foss. des 
 Terr. Pal., p. -261, 1851), but that they subsequently accepted 
 the genus as distinct (Brit. Foss. Cor., p. 264, 1854). In this 
 course whatever differences of opinion as to the affinities of 
 the genus may have been expressed Milne- Ed wards and 
 Haime have been followed by almost all palaeontologists. For 
 my own part, as previously mentioned in speaking of Chcetetes, 
 I have been disposed to consider that no sufficient characters 
 had been indicated whereby Monticulipora, D'Orb., could be 
 separated generically from Chcetetes, Fischer; and I have de- 
 scribed a number of species of the former genus under the 
 latter title. Having now, however, had the opportunity of 
 examining authentic specimens of the type-species of Chcetetcs 
 (the C. radians, Fischer, of Russia), I am quite satisfied as to 
 the complete distinctness of this genus, and, consequently, as 
 to the necessity for retaining the genus Monticulipora, 
 
 The genus Monticulipora using this term in the meanwhile 
 in a wide general sense includes Palaeozoic coralla of the most 
 variable form. In many cases the corallum is massive, con- 
 sisting of a variably-shaped aggregation of diverging corallites 
 based upon an inferior epitheca, and having the calices placed 
 exclusively upon the upper surface. In other cases, including, 
 perhaps, the majority of species, the corallum is ramose, or 
 dendroid, fixed by its base, and having the calices opening over 
 the whole of the free surface. In another group the corallum 
 is fixed by its base, but has the form of a flattened, palmate, 
 and variously-divided frond, the corallites diverging from the 
 imaginary median plane of the expansion and opening on the 
 two flat surfaces. In still another group, the corallum forms 
 a thin crust, growing parasitically upon foreign bodies ; but 
 though some undoubted species of the genus have this habit, it 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 273 
 
 is probable that a considerable number of the so-called en- 
 crusting Monticulipora will prove, upon adequate examination, 
 to be truly of a Polyzoan nature. Be this as it may, it is quite 
 certain that the mere form of the corallum, though affording a 
 useful guide to the collector, is usually of no value whatever in 
 determining the structure and affinities of a given specimen of 
 Monticulipora. As an illustration of this fact, -I may mention 
 that among the corals which, from their general form and 
 superficial characters, would unhesitatingly be placed under the 
 well-known species M. petropolitana, Pand., I find at least 
 three well-marked types to be included, which differ so widely 
 from one another in minute structure, that they might well be 
 regarded as at least distinct sub-genera. At the same time, 
 certain species, and especially those which have a laminar or 
 frondescent corallum, are very constant in their mode of 
 growth, so that in these cases the form of the corallum really is 
 of value in the determination of species ; while" the ramose 
 species, however variable, never appear to form crusts on 
 foreign bodies, as some of the massive species occasionally do. 
 The corallites in Monticulipora may be distinctly prismatic or 
 polygonal, or they may be rounded and nearly cylindrical, but 
 in either case they are always in close contact, and they never 
 really exhibit the condition of parts characteristic of Chcetetes 
 proper, in which, as has been shown, the walls of contiguous 
 corallites are so completely amalgamated that the original lines 
 of demarcation between neighbouring tubes cannot be in any 
 way detected. In some cases (e.g., in the typical M. petropoli- 
 tana, Pand.) the walls are so thin that the partitions between 
 the visceral chambers of contiguous corallites appear to be 
 absolutely indivisible, and present themselves in thin sections 
 merely as delicate dark lines (fig. 35, A). This is, however, a 
 state of parts very different to what occurs in Chcetetes proper 
 (fig- 35 D ) an d i s much more nearly comparable to what we 
 observe in many species of Favosites. In other cases, the 
 condition of things is very like that observable in Favositis 
 generally, in which the walls of contiguous tubes are distinct, 
 
 s 
 
274 
 
 TABULATE CORALS. 
 
 and the line of demarcation between them remains clearly 
 marked out in cross-sections of the corallites (fig. 35, c). This 
 occurs, for example, in typical specimens of M. pulchella, E. 
 
 Fig. 35. A, Tangential section of a few corallites of the typical Monticulipora pctropolitana, 
 Pand., from the Lower Silurian of Sweden; B, Tangential section of a corallite of a typi- 
 cal example of Monticulipora ramosa, E. and H. , from the Cincinnati group of Ohio ; C, 
 Tangential section of a corallite of Monticulipora pulchella, E. and H., a typical example 
 from the Wenlock Limestone of Dudley; D, Tangential section of a corallite of the typi- 
 cal Chatties radians, Pand., of the Carboniferous rocks of Russia. All the sections are 
 taken just below the calices ; A, B, and c are enlarged fifty times ; D enlarged twenty- 
 five times. 
 
 and H., from the Wenlock Limestone of England. In still 
 another group of cases, embracing many typical species of the 
 genus (e.g., M. mammulata, D'Orb.), there is no dark line 
 running in the centre of the partition between contiguous tubes, 
 and tKe walls thus at first sight appear to be amalgamated, as 
 they actually are in Chatctes proper. In these cases, however 
 (fig. 35, B), the state of matters really differs widely from that 
 which exists in Ch&tetes proper, since each visceral chamber is 
 enclosed by a distinct dark line, usually circular or oval in out- 
 line, marking the original boundary of the tube, and the inter- 
 spaces between these dark lines are filled in by sclerenchyma of 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 275 
 
 a different texture and much lighter colour. In these cases, 
 therefore, it would appear that the corallites are not only primi- 
 tively distinct, but that in approaching the surface they do not 
 touch each other at all to begin with, or only to a very limited 
 extent, the ultimate union of the corallites being effected by 
 means of a secondary deposit of calcareous matter. In such 
 forms as these, therefore, the corallites in the deeper parts of 
 the corallum are thin-walled, closely contiguous, and more or 
 less polygonal; whereas they become much thickened and 
 more conspicuously circular or oval in shape as their mouths 
 are approached. The structure of the wall is, in fact, very 
 similar in these cases to what is observable in Stenopora, 
 Lonsd., except that the thickening of the tubes is uniform, and 
 is not confined to the production of periodic rings. 
 
 Apart from the evidence of microscopic sections, into which 
 I cannot fully enter here, the permanent non-amalgamation of 
 the walls of the corallites in Monticulipora is shown by the fact 
 that fractured surfaces invariably exhibit the exterior of the 
 tubes. This was long ago noticed by Lonsdale, and was set 
 down by him to the fact that the corallum of Monticulipora 
 increased by gemmation, whereas that of Chatetes produced 
 new tubes by a process of fission. In the latter, therefore, 
 rough fractures exhibit the interior of the corallites. Of the 
 correctness of Lonsdale's observations on this point as obser- 
 vations I can entertain no doubt; but I am not clear that the 
 phenomena are really due to the cause which he assigns. That 
 Chcetetes increases fissiparously is certain ; but I am not sure 
 that gemmation is the regular or exclusive mode of growth 
 amongst the Monticulipora. I have formerly expressed the 
 opinion (Ann. Nat. Hist, ser. 4, vol. xviii. p. 86) that certain 
 species of Monticulipora exhibited fissiparous growth ; and 
 though further observations have shown me that I relied upon 
 evidence which admitted of misconstruction, and that gem- 
 mation is the common mode of increase in the Monticuliporte, 
 I am still inclined to think that the phenomena manifested by 
 thin sections show that fission of the old tubes occurs at times 
 
 
276 TABULATE CORALS. 
 
 as well. At any rate, I feel sure that the difficulty of deter- 
 mining this point in the case of the smaller species is so great 
 that I am right in the formerly expressed opinion that this 
 character alone should not be accepted as an adequate generic 
 distinction between Chcetetes and Monticulipora (Quart. Journ. 
 Geol. Soc., vol. xxx. p. 500). 
 
 There is at present no evidence as to the existence of 
 " mural pores " in Monticulipora or its allies. Considering the 
 minute size of the tubes, and the great difficulties which com- 
 monly attend the detection of these apertures in microscopic 
 sections, the non-recognition of pores does not absolutely imply 
 their non-existence. We know that pores are present in the 
 similar-looking Stenopora, Lonsd.; I have previously shown that 
 similar apertures exist in the Favosites Bowerbanki, E. and H. 
 sp. of the Upper Silurian, which has hitherto been regarded as 
 a Monticulipora; and, as before remarked, I have recently 
 examined a specimen from the Upper Silurian of Dudley, in 
 which the general characters of Monticulipora are present, but 
 the walls are minutely porous. Moreover, the microscopic ex- 
 amination of weathered or fractured surfaces often brings to 
 light deficiencies in the walls of the tubes, though whether these 
 are accidental, or are really of the nature of " mural pores," is a 
 point upon which I have hitherto been unable to satisfy myself. 
 In the want of direct and positive evidence, we must at present 
 assume the walls in Monticulipora and its allies to be imper- 
 forate. At the same time I should not be surprised if future 
 and more extended investigations should show that mural pores 
 really exist ; though it may be safely assumed that any struc- 
 tures of this kind that may be detected will prove to be pro- 
 portionately more minute, and more irregular in their size and 
 distribution, than is the case with these openings in the typical 
 Favositidce. 
 
 Whatever may be the condition of the walls in Monticulipora, 
 microscopic examination brings out very clearly the important 
 fact that in the vast majority of cases, and probably invariably, 
 the corallum is truly dimorphic, and consists of two different 
 
GENERA OF CH&TJ&TWM AND MONTICULIPORID^,. 277 
 
 sets of corallites, which must, during life, have been inhabited 
 by different sets of zooids. The existence of minute tubes, 
 either scattered among the larger ones, or aggregated in 
 special groups, has, of course, been long known to palaeontolo- 
 gists ; but these have, for the most part, been regarded either 
 as merely young corallites or as " coenenchymal tubuli." 
 Similarly, palaeontologists have long known that certain species 
 of Monticulipora (e.g., M. pulchella, E. and H.) exhibit groups 
 of large tubes distributed at intervals among those of average 
 size ; but the true import of these appearances hardly admitted 
 of recognition save by the light of Mr Moseley's researches 
 upon the living Heliopora. I have, however, now thoroughly 
 satisfied myself that the corallum in Monticulipora is truly 
 dimorphic, quite as genuinely as in Heliopora or Heliolites. 
 One set of corallites may be much reduced in number, or may 
 undergo much modification, but I believe that the existence of 
 two different kinds of tubes can almost always be demon- 
 strated ; and the importance of this fact, from a theoretical 
 point of view, can hardly be over-estimated. The relations of 
 the two sets of tubes to one another vary extremely in different 
 forms of Monticulipora, and I shall employ these variations as 
 the basis of a provisional classification of the multitudinous 
 forms included under this head. I shall, therefore, postpone a 
 further consideration of this subject till I come to speak of the 
 different groups which may be comprehended under the general 
 name of Monticulipora. 
 
 I must, however, briefly notice here certain peculiar super- 
 ficial features in different species of Monticulipora, which are 
 in reality due to the dimorphic condition of the corallum just 
 spoken of. The appearances presented by the calices vary 
 according as we have to deal with a form in which the walls of 
 the corallites remain permanently more or less thin throughout 
 their entire extent, or with one in which the tubes undergo a 
 marked thickening before reaching the surface. In the former 
 of these cases the calices are polygonal and sharp-edged, and 
 thus resemble the calices in a Favosites of the normal type. In 
 
278 TABULATE CORALS. 
 
 the second case, the calices are rounded, oval, or subpolygonal, 
 and exhibit thick and rounded margins reminding us, so far 
 as this particular character goes, of the calices of a Pachypora 
 or a Stenopora. Monticulipora petropolitana, Pand., and its 
 allies may be taken as exemplifying the former condition ; 
 while M. ramosa, D'Orb., M. mammulata, D'Orb., M. frondosa, 
 D'Orb., M. Jamesi, Nich., M. tumida, Phill., and many others, 
 are examples of the latter state of parts. Those forms, more- 
 over, in which the walls are thickened towards the surface are 
 particularly liable to exhibit a feature, sometimes seen in the 
 thin-walled species, and common to most or all of the species 
 of Stenopora, Lonsd., which demands a little consideration here, 
 though its true significance is still somewhat dubious. I allude 
 to the occurrence of peculiar blunt spine-like structures, which 
 are placed, in greater or less numbers, round the calices, usually 
 at the angles of union of the corallites. Various Monticuli- 
 poroid Palaeozoic corals have been noticed by various observers 
 to possess these calicine spines ; and Milne-Edwards and 
 Haime at one time (Brit. Foss. Cor. Intr., p. Ixi) regarded the 
 existence of these structures as diagnostic of the genus Steno- 
 pora as defined by them. Structures of this nature are, how- 
 ever, possessed by a large number of true Monticuliporce, and, 
 notably, by M. frondosa, D'Orb., M. tumida, Phill., M. Jamesi, 
 Nich., M. moniliformis, Nich. (figs. 36, 37), M. gracilis, James, 
 and other forms. As viewed from the surface, these spines 
 present themselves simply as so many blunt projections, which 
 do not seem, so far as I have been able to observe, to be per- 
 forated by any apical apertures. When examined by means of 
 thin sections, however, these spines are found to be in no way 
 of the nature of mere superficial ornaments, but they extend 
 into the substance of the corallum, between the ordinary coral- 
 lites, to a depth equal to that reached by the smaller tubes of 
 the colony. Tangential sections taken a little below the sur- 
 face (fig. 37) show that these apparent spines are composed of 
 concentrically laminated sclerenchyma, exhibiting in their centre 
 a dark circular spot or a clear circular space. There cannot, 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 279 
 
 therefore, be any doubt but that these structures are primitively 
 hollow, though their central cavities often appear to become 
 filled up by a secondary deposit of sclerenchyma, as growth 
 
 Fig- 36. a, Fragment of Monticitli- Fig. 37. Portion of a tangential section of Monti- 
 
 para moniliformis, Nich., from 
 the Hamilton Group of Ontario, 
 enlarged ; b, Portion of surface of 
 same enlarged further ; <r, Portion 
 of surface of M. Barrandi, Nich., 
 enlarged. 
 
 cttlipora moniliformis, Nich., taken just below 
 the surface, showing the intracalicine spines, 
 enlarged fifty times. From the Hamilton 
 Group of Ontario. 
 
 proceeds. In this primordial hollo wness of the spines is to be 
 found, I believe, the real clue to their nature ; and I can hardly 
 doubt that instead of being merely appendages of the corallum, 
 they are truly of the nature of peculiarly modified zooids or coral- 
 lites. The correctness of this view is most readily recognised 
 when we come to examine thin sections of those forms which have 
 usually been separated from Monticulipora under the generic 
 title of Dekayia, E. and H. In these cases (PI. XV., figs, i b, 
 i c} the supposed spines are very much reduced in number, but 
 they are quite exceptionally developed, and they constitute the 
 well-known surface-projections, which are characteristic of the 
 genus. These surface-projections certainly seem to be imper- 
 forate at their apices, but thin sections demonstrate conclusively 
 that they are hollow internally, and that they only differ from 
 the ordinary corallites in the greater thickness and density of 
 their walls and the apparent absence of tabulae. I do not myself 
 entertain any doubt as to these being a peculiar form of coral- 
 lites doubtless tenanted in life by peculiar zooids the mouths 
 
2 8o TABULATE CORALS. 
 
 of which became closed by secondary deposit as the corallum 
 assumed its final characters. Nor have I any doubt that the 
 spines of forms like M. moniliformis, Nich. (figs. 36, 37), M. 
 Jamesi, Nich., M. tumida, Phill., M. gracilis, James, and others, 
 are similarly peculiarly modified corallites, the mouths of which 
 become finally closed. A further evidence of this is to be 
 found in such species as M. frondosa, D'Orb., in which the 
 spines do not appear as spines upon the surface, though thin 
 sections exhibit appearances precisely similar to what has been 
 indicated as occurring in the forms alluded to above. On the 
 contrary, the spines remain permanently open, and appear on 
 the surface as minute thickened apertures between the ordinary 
 calices, so that they have been both recognised and figured as 
 a special group of corallites (Ann. and Mag. Nat. Hist, ser. 4, 
 vol. xviii. p. 92, PI. V., fig. 1 1). Lastly, if we admit the prob- 
 able correctness of the views here advanced, we have a very 
 interesting analogy established between certain forms of Monti- 
 culipora and some of the species of Stenopora, Lonsd., in which 
 structures of a precisely similar nature occur. Thus, if we 
 examine a tangential section of Stenopora Tasmaniensis, Lonsd., 
 taken just below the surface (fig. 38), we see that the surface- 
 spines are continued inwards precisely as they are in Monti- 
 culipora moniliformis and allied types, while they are similarly 
 composed of concentrically-disposed lamellae of dense scleren- 
 chyma. The central cavities of the spines seem, however, to 
 be more or less completely obliterated with age ; and the coral- 
 lites in the outer portion of their course (fig. 38, A) exhibit the 
 annular thickenings of their walls which are so characteristic of 
 the genus Stenopora. In spite of these differences, the resem- 
 blance between the spines of the Monticuliporcs above alluded 
 to and the similar structures in certain species of Stenopora is 
 so striking that one can hardly resist the conviction that there 
 must subsist between the two a relationship of real affinity. 
 
 More conspicuous, more generally familiar, and more uni- 
 formly present than the spines, are those structures in the 
 Monticulipora, which are known as " monticules " and " macu- 
 
GENERA OF CH^ETETID^E AND MONTICULIPORIDsE. 281 
 
 lae." The "monticules" or "mamelons" are circumscribed 
 areas on the surface of the corallum, which are, typically, ele- 
 vated so as to form a series of rounded, oval, or elongated 
 
 Fig. 38. A, Vertical section of a few of the corallites of Stenopora Tasmaniensis, Lonsd., in 
 the final portion of their course, enlarged twenty times, showing the annular thickenings 
 of the tubes and the remote tabulae ; B, Tangential section of the same, taken just below 
 the surface, similarly enlarged, showing the transversely divided spiniform corallites be- 
 tween the ordinary tubes. Carboniferous, Australia. 
 
 projections, but which may be nearly or quite level with the 
 general surface. Sometimes the " monticules " are composed 
 of corallites which differ in no conspicuous feature from those 
 which form the rest of the coral (e.g., in M. ramosa, D'Orb.) ; 
 in other cases (e.g., M. pulchella, E. and H.) the corallites 
 which form the " monticules " are of a markedly larger size 
 than the average; while in still other forms (e.g., M.frondosa, 
 D'Orb.) the "monticules" in this case flat are occupied by 
 corallites much more minute in their size than those which 
 form the bulk of the colony. The so-called " maculae " are 
 simply " monticules," in which the mouths of the tubes have 
 become closed by a calcareous membrane. 
 
 The only other point as regards the structure of the Monti- 
 culiporce which need specially be noticed here concerns the dis- 
 position of the tabulcz. These structures are invariably present 
 in the typical Monticuliporcz , and are almost invariably " com- 
 
282 TABULATE CORALS. 
 
 plete." The only exception to the latter part of this statement 
 with which I am acquainted is the curious M. frondosa, D'Orb., 
 in which the tabulae seem to have the form of crescentic dia- 
 phragms, with an excentric aperture or perforation on one side. 
 As a rule, the tabulae are very sparsely developed in the axial 
 and deeper portions of the corallum, and become much more 
 numerous as the tubes approach the surface. As a rule, also, 
 the tabulae are conspicuously more numerous and more closely 
 set in the smaller corallites of the two sets of tubes of which the 
 corallum is normally composed. In a few forms, lastly, the 
 tabulae may become curved, so as to assume a subvesicular or 
 vesicular aspect ; but this is quite an exceptional feature. 
 
 With regard to " septa " in the Monticulipor& t it need only 
 be said that no traces of these structures have hitherto been 
 detected in any Monticuliporoid. Occasionally one may see 
 in thin transverse or tangential sections a single azygous septum 
 projecting for some distance into the interior of a tube, but this 
 seems to be really the result of fission of a corallite, as we have 
 seen to be the case in Chcetetes. 
 
 As regards the development of the Monticuliporce I have little 
 to say from actual observation, and that little will be best said 
 after I have given some account of the views held upon this 
 subject by Dr Gustav Lindstrom (Ann. Nat. Hist., sen 4, vol. 
 xviii. p. 5 et seg.} As I find myself in this matter unable to 
 accept the conclusions of the distinguished Swedish palaeon- 
 tologist, it is only just that I should quote his account of the 
 development of Monticulipora at length. Upon this point he 
 remarks : 
 
 "If numerous specimens of the common M. petropolitana, 
 Pand., be closely scrutinised, it will be seen that its semi-globose 
 colony, so closely resembling a Favosites in its initial develop- 
 ment, has an origin that could hardly be suspected. It begins, 
 indeed, as a Bryozoon, as a Discoporella> as what Hall has 
 termed Ceramopora imbricata (Pal. N.Y., vol. ii. p. 169, PI. 40 
 E, figs, i a-i t). There can be no doubt that this is closely 
 allied to the recent Discoporella (see Fr. Smitt, Ofv. Vet. Akad. 
 
GENERA OF CH^TETID^E AND MONTICULIPORIDJE. 283 
 
 Forhand. 1866, p. 476, PI. XI., fig. 4). The basal surface of 
 a Monticulipora, when the epitheca is very thin, clearly shows 
 that it is in its first origin a Ceramopora. The smallest Ceramo- 
 porce which I have hitherto seen consist of a thin circular disc 
 with elevated edges. From the smooth centre of the superior 
 surface four or five wedge-shaped zocecia radiate outwards, each 
 of a length of i-5th millim., their mouths being oblique, with 
 the inferior lip somewhat protracted. On both sides of the 
 mouth there is a short, pointed spine. In its interior such a 
 zocecium is transversely divided by some irregular tabulse. The 
 interstitial tubes which are so characteristic of the Discoporel- 
 lidce are also distinctly seen between the zocecia of Ceramopora. 
 New zocecia are budded forth in quincunx from the corner of 
 the old zocecia, and in the periphery of the colony they become 
 more crowded, having the mouth oval and erected. In the 
 interstices is seen what might be taken for a ccenenchyma ; but 
 this in reality is composed of nothing but smaller irregular 
 zocecia. When the colony has spread out laterally, there are 
 seen at the sides of the first smooth centrum several others 
 regularly distributed on the surface, from which zocecia radiate 
 just as if the disc were composed of an aggregation of coales- 
 cent initial buds. When the colony has thus gained the expanse 
 of an inch or more, the zocecia grow vertically upwards, and the 
 colony by-and-by assumes a semi-globular shape, and is con- 
 verted into a Monticulipora. All the zocecia are then tubular, 
 their mouths quite circular, and armed with a pair of very short 
 spines, their size varying in different cases. The larger zocecia 
 have around them either an empty space, or, as above stated, 
 a cellular tissue resembling a ccenenchyma, and consisting of 
 smaller circular or polygonal tubes. The walls of the zocecia 
 are solid, without any perforations, and interiorly quite smooth 
 and destitute of projecting ridges or septa. The tabulae are 
 very irregular in the large tubes, being oblique or deeply sunk 
 in the wall ; in the narrower tubes they are dense and regular. 
 The large zocecia are clustered in groups at tolerably regular 
 intervals, each group of six or eight members. In Upper 
 
284 TABULATE CORALS. 
 
 Silurian specimens they very seldom project above the surface, 
 and do not form the strange monticules which are so common 
 on the surface of the Russian Lower Silurian specimens. I 
 suppose that these clusters are continuations from the original 
 and larger zocecia, which were budded out round the smooth 
 centra when the colony was in its Ceramopora stage. In some 
 there is seen a sort of ' reversion/ the zocecia on the surface of 
 the Monticulipora having again assumed the unmistakable 
 characters of Bryozoon, becoming oblique and radiating as 
 in a Ceramopora. Longitudinal sections, however, demon- 
 strate that there is a direct continuation from the tubes of the 
 Monticulipora into those of the Ceramopora, or that the former 
 again have changed into the latter." 
 
 Having thus described what he believes to be the mode of 
 development in Monticulipora petropolitana, Pand., Dr Lind- 
 strom proceeds to give an account of the development of a 
 Silurian fossil which he terms Monticulipora ostiolata, and which 
 he identifies with the Trematopora ostiolata of Hall (Pal. N.Y., 
 vol. ii. p. 152, PI. XL., fig. 5), with the Nebulipora papillata of 
 M'Coy (M. papillata, E. and H., Brit. Foss. Cor., p. 266, PI. 
 LXIL, fig. 4), and with Thecostegites hemisphericus of Ferd. 
 Roemer (Sil. Faun, of Tennessee, p. 25, PI. II., figs. 3, 3 a}. 
 This form is stated by Dr Lindstrom to commence its existence 
 as a Discoporella, and then to pass into what may be called the 
 " Fistulipora stage," each cell being now " surrounded by a 
 mass of small vertical, circular, or polygonal tubes having the 
 appearance of a ccenenchyma," and all the tubes, both large 
 and small, being " traversed by tabulae of the same incomplete 
 type as those which characterise Monticulipora!' * From this 
 "Fistulipora stage" the colony is stated to pass next into what 
 Dr Lindstrom calls the " Tkecostegites stage," in which the 
 interstitial tubes become covered with "a thin smooth calcare- 
 ous membrane," leaving the larger tubes open, and causing 
 
 1 I do not understand precisely what Dr Lindstrom may mean by " incomplete" 
 tabulse; but the tabulae of almost all the Monticulipora that I have examined, 
 except M.frondosa, D'Orb., are just as "complete " as they are in the typical mem- 
 bers of the Favositida. 
 
GENERA OF CH^ETETID^. AND MONTICULIPORIDM. 285 
 
 their mouths to assume a circular or oval shape, and to project 
 above the general surface. Lastly, the fossil is said to change 
 into a Monticulipora by the development of regular " monti- 
 cules," which are " arranged in quincunx, and formed at the 
 points where seven or eight large cells are clustered." 
 
 In the preceding I have endeavoured to give a faithful 
 account of the views which Dr Lindstrom has published as 
 to the development of the Monticuliporce, and upon which 
 he, in large part, bases his view that the fossils of this genus 
 are really Polyzoa. Not having had the opportunity of per- 
 sonally examining the specimens upon which his views are 
 based, it would be presumption on my part were I to impugn 
 the accuracy of the description which he has given of the 
 phenomena which he has observed the more so as his justly 
 deserved reputation is a guarantee that he has not arrived 
 at the conclusions in question without sufficient consideration. 
 At the same time, I regret to find myself in the meanwhile 
 unable to accept these conclusions ; and though I cannot 
 here enter into the subject at length, I may just briefly 
 indicate the principal reasons which lead me to dissent from 
 the views of such a high authority upon this and kindred 
 questions. In the first place, then, it is clear that the study 
 of the development of a fossil organism is attended with 
 difficulties much more serious than those which are incidental 
 to a similar investigation in the case of a living animal ; since 
 in the latter it is generally possible to trace the actual tran- 
 sition from one stage of growth to another. This, by the 
 nature of the case, is rarely one might almost say never pos- 
 sible in the case of a fossil. It is true that in the passage of 
 what he has termed the " Fistulipora, stage" to the " Thecoste- 
 gites stage," Dr Lindstrom states that he has actually seen the 
 same specimen exhibiting the characters of both stages in dif- 
 ferent parts of its skeleton. Still the passage between the two 
 stages just referred to is a comparatively small step to make, 
 and it does not affect the fact that Dr Lindstrom has not 
 observed so far as I am able to understand his very clear 
 
2 86 TABULATE CORALS. 
 
 account the actual transition between an undoubted encrust- 
 ing Ceramopora and an undoubted free and discoidal specimen 
 of Monticulipora petropolitana, Pand. He has examined cer- 
 tain specimens which show characters linking the one on to 
 the other ; but I do not understand him to assert that he has 
 examined specimens which in one portion show the unmistak- 
 able characters of Ceramopora, and which in another, demon- 
 strably older, portion exhibit the features proper to Monticuli- 
 pora. I cannot, however, accept any specimens except such 
 as exhibit as individuals the characters of two types, as being 
 proof that either of the types in question has been developed 
 out of the other. In the second place, apart from this general 
 argument, which may easily be pushed too far, there are very 
 strong grounds for regarding Ceramopora as an independent 
 organism quite distinct from all the forms of Monticulipora. 
 Thus Ceramopora is most abundant in Upper Silurian and 
 Devonian strata, in which Monticulipora are comparatively 
 rare fossils, while the genus is very poorly represented in 
 Lower Silurian strata (such as the Cincinnati formation in 
 North America), in which Monticulipora are excessively abun- 
 dant. An additional proof of the distinctness of Ceramopora 
 is found in the fact that it grows to a large size, preserving 
 unchanged its normal and proper characters, while the general 
 structure and form of its tubes are markedly unlike those of 
 the corallites of the Monticuliporce, being reclined, with oblique 
 and crescentic mouths, and, so far as I have observed, wholly 
 devoid of tabulae. (Dr Lindstrom states that tabulae exist in 
 Ceramopora, but I have been unable to detect these structures 
 in thin sections ; though I have found tabulae in some specimens 
 of a Monticulipora from the Wenlock Limestone of Dudley, 
 which may perhaps be the M. papillata of M'Coy, and which 
 certainly has more of the look of a Polyzoon than is usual in 
 species of Monticulipora^ Moreover, the colonies of Cera- 
 mopora are usually (always ?) fixed, being attached parasiti- 
 cally by a portion or the whole of the lower surface to some 
 foreign body ; whereas the corallum in the discoid species of 
 
GENERA OF CHsETETID^ AND MONTICULIPORID&. 287 
 
 Monticulipora> supposed to be developed out of the former, 
 is usually and normally free ; but it is very difficult to explain 
 this fact if there be any genetic relationship between the 
 two. Thirdly, as regards matters of actual observation, I have 
 never been able to detect anything of the nature of a " Cera- 
 mopora stage" in young Monticuliporce. This is a point 
 which is most easily observed in young examples of the dis- 
 coidal species of Monticulipora, such as M. petropolitana> and 
 the various forms allied to this ; and I can only say that the 
 most minute examples of these forms which have come under 
 my notice differ in no respect whatever, that I can detect, ex- 
 cept size, as regards their external and internal characters, from 
 fully-grown specimens. Fourthly, if it were the case that dis- 
 coidal species of Monticulipora, such as M. petropolitana, Pand., 
 grew out of the thin parasitic crusts to which Hall applied the 
 name of Ceramopora, we ought to be able to detect the primi- 
 tive " Ceramoporoid " portion of the colony at the base of thin 
 vertical sections of colonies of the former. I have, however, 
 examined a large number of such sections, and I have been 
 unable to detect any difference in the structure of the lowest 
 portion of the tubes, resting directly upon the basal epitheca, 
 as compared with that of the fully-grown portion of the coral- 
 lites. Dr Lindstrom states that the basal surface of a Monti- 
 c^ll^pora, when its epitheca is very thin, " clearly shows that it 
 is a Ceramopora" but I am unable to concur in this statement. 
 If the specimen be undoubtedly one of Monticulipora, then I 
 have never seen anything in its epithecal surface which could 
 be compared with the structure of Ceramopora. All that can 
 be said, in my opinion, on this point is that we meet in the 
 Palaeozoic rocks with specimens of the thin discoidal epithecse 
 of certain fossils (the Lichenalia of Hall), which look like the 
 under surface of the epithecal plate of Monticulipora petro- 
 politana, Pand., but which might be really referable to quite 
 different forms, and which mostly cannot, without the prepara- 
 tion of thin sections, be definitely referred either to the Ccelen- 
 terata or the Polyzoa. Lastly, as regards the assertion that 
 
288 TABULATE CORALS. 
 
 certain Monticulipora pass through a " Fistulipora stage," and 
 the apparent conclusion therefrom that Fistulipora, M'Coy, is 
 only a temporary condition of Monticulipora, I think it may be 
 said that the point at issue is narrowed essentially to a ques- 
 tion of words ;. for I hope to show that in one sense the great 
 majority of the Monticulipor<z are truly Fistuliporce. That is 
 to say, I think it can be shown that the forms which M'Coy 
 included under the name Fistulipora, and which Hall has 
 subsequently termed Callopora^ are, at most, mere subgeneric 
 forms of Monticulipora. I shall show, namely, that the pos- 
 session of a dimorphic corallum is a common feature in all the 
 Monticidiporte properly so called, and that the Fistuliporce are 
 only peculiar in the fact that they exhibit a special develop- 
 ment of the smaller tubes of the corallum. If this be admitted, 
 it is clear that the passage of a given species of Monticidipora 
 through a " Fistulipora stage " is a matter of comparatively 
 small importance from a theoretical point of view. At the 
 same time, I shall endeavour to show that the forms .included 
 under the names of Fistulipora, M'Coy, and Callopora, Hall, 
 have a real existence, in so far that the characters which dis- 
 tinguish these types are not of a merely temporary and tran- 
 sient nature, but that they' exist in unquestionably adult 
 examples. 
 
 As regards the zoological position of the Monticuliporid<z, 
 there has been of late, as is well known, a strong tendency on 
 the part of palaeontologists to remove them from the Coelenter- 
 ata, and to relegate them to the Polyzoa. Some of the grounds 
 upon which this step has been proposed merely concern the 
 general resemblance in external characters between the Mon- 
 ticuliporoids and certain of the Polyzoa (such as Heteropord) ; 
 and I have already expressed my opinion of the value of this 
 resemblance in speaking of the systematic position of Chcztetes, 
 Fischer. The only positive and direct evidence in favour of 
 the removal of the Monticuliporce to the Polyzoa is to be found 
 in the account of the development of the former as given by 
 Lindstrom, and I have given the reasons which prevent me 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^. 289 
 
 from accepting that account. Without, then, going into this 
 question in detail, I may simply say that I see at present no 
 sufficient ground for removing the Monticuliporoids to the 
 Polyzoa. I do not think any weight can be attached to external 
 appearance in a matter of this kind. Thus, we find the com- 
 mon Favosites Canadensis, Billings sp., of the Devonian of 
 Canada, to be so entirely similar in the form and appearance 
 of its colonies to examples of Fistulipora, M'Coy, that it was 
 unhesitatingly referred to this genus (which Dr Lindstrom re- 
 gards as clearly Polyzoan) by Mr Billings and myself. Dr 
 Rominger, however, showed that it has " mural pores " of the 
 regular Favositoid type a discovery which I have myself 
 verified so that in place of being a Fistulipora, and, there- 
 fore, according to Dr Lindstrom, a Polyzoon, it is a true Per- 
 forate Coral. A position among the Favositidce has similarly 
 been now established as the right one for Stenopora, Lonsd., 
 which includes forms so like Chcstetes and Monticulipora in 
 general aspect as to have been commonly included under one 
 or other of the latter heads. Apart from mere superficial 
 appearances which in this case speak at least as strongly for 
 a Ccelenterate as a Polyzoan alliance there is nothing in the 
 actual structure of Monticulipora which would not entirely 
 agree with its being a coral. The only point which could be 
 mentioned which would in any fundamental manner distinguish 
 the internal structure of a Monticulipora from that of, say, 
 Tetradium or Heliolites, is the absence in the former of septa. 
 I do not, however, attach any weight to this, partly because 
 some undoubted corals are equally without septa, partly because 
 the septa in Heliolites and its allies are now known by the 
 researches of Moseley to be only " pseudo-septa," and partly 
 because I do not think that any important change in classifica- 
 tion should be based upon a merely negative character. On 
 the other hand, there are strong resemblances between Mon- 
 ticulipora and its allies and various undoubted corals prin- 
 cipally, perhaps, the Helioporidcz. Thus the " tabulae " of the 
 Monticuliporoids are in all respects similar to those of such 
 
2 9 o TABULATE CORALS. 
 
 undoubted corals as Favosites among the Zoantharia, and 
 Heliolites among the Alcyonaria. Again, there is the import- 
 ant character that the corallum of the Monticuliporoids can be 
 shown to be almost always (I expect, always) dimorphic, con- 
 sisting of two distinct sets of corallites, of different sizes, and 
 mostly with a different internal structure. This last character 
 reminds us so strongly of the Helioporidce to which there 
 are other mentionable points of likeness that I am at present 
 disposed to regard the Monticuliporidce as an ancient group 
 of the Alcyonaria. 
 
 As for the relations of Monticulipora to other types of the 
 so-called " Tabulate Corals," the genus is separated from all 
 the Favositidce, including the similar-looking Stenopora, Lonsd., 
 by the possession of imperforate walls to the corallites. 1 Ad- 
 mitting the absence of mural pores, in the want of direct evi- 
 dence to the contrary, we have only to compare Monticulipora 
 with a very limited number of types, of which the most im- 
 portant is Chcetetes of Fischer. From this latter the present 
 genus is sufficiently distinguished by the non-amalgamation of 
 the walls of contiguous corallites, by the want of the curious 
 vertical ridge which is found in the interior of many of the 
 corallites of Ch&tetes, and by the possession of two sets of 
 corallites in the corallum, one set of tubes being commonly 
 disposed in special groups. From Tetradium, Dana, Monti- 
 culipora is sufficiently distinguished by its total want of septa 
 and by the dimorphic structure of the corallum. To Heliolites 
 and its allies the various types included under the general 
 name of Monticulipora present a considerable alliance, especi- 
 ally if we compare the structure of such a form as Fistulipora 
 (Callopora) incrassata, Nich., with that of a form like Propora 
 tubulata, E. and H. The absence of septa is, however, 
 sufficient to distinguish Monticulipora from the Helioporidce. 
 
 1 As before remarked, it is not impossible that "mural pores" may yet be demon- 
 strated to exist in Monticiilipora. This is the more likely, if we remember that 
 these openings have as yet been absolutely demonstrated in only two species of 
 Stenopora ; so that some exceptionally well preserved specimen, or some lucky sec- 
 tion, may bring them to light in the Monticuliporoids at any time. 
 
GENERA OF CH^TETID^E AND MONTICULIPORID^E. 291 
 
 From Prasopora, Nich. and Eth., jun., Monticulipora is dis- 
 tinguishable only by the very peculiar structure of the tabulae 
 of the former. Lastly, I need not attempt to differentiate from 
 Monticulipora the types known by the names of Dekayia, E. and 
 H., Constellaria> Dana, and Fistulipora, M'Coy ( = Callopora, 
 Hall), as I shall include all these under the former genus, re- 
 taining their titles as of subgeneric value, and shall, therefore, 
 speak of them at greater length hereafter. 
 
 The number of forms included under the comprehensive 
 title of Monticulipora, D'Orb., is so large, and the variations 
 in the minute structure of these are so important, that the 
 genus must of necessity be split up into sections, which may 
 be distinguished by separate names. It is impossible here for 
 me to give anything like a full account of my researches into 
 this subject, and I shall, therefore, content myself with simply 
 giving a brief summary of the general conclusions at which I 
 have arrived, together with short descriptions of some illustra- 
 tive species of the genus. Taking the intimate structure of 
 the corallum as the sole reliable basis for the subdivision of the 
 genus, I propose to include under the general name of Monti- 
 culipora^ D'Orb., the following six subgeneric groups, which 
 will be best designated by special titles, and some of which 
 have been previously described as distinct genera. 
 
 I. HETEROTRYPA, Nich. Corallites of two or sometimes of 
 three kinds ; the larger ones subpolygonal, partially separated 
 by the development of numerous smaller circular or irregularly- 
 shaped tubes, of which there is no more than a single row. 
 Walls thickened towards the mouths of the tubes. Tabulae 
 conspicuously more numerous in the smaller tubes than in the 
 larger ones. Type of the group the Monticulipora mammulata, 
 D'Orb. (which is also the type of the whole genus). 
 
 II. DEKAYIA, Edwards and Haime. Corallites of two kinds, 
 the larger tubes with thin walls, polygonal in shape, and pro- 
 vided with well-developed tabulae. The smaller tubes isolated 
 by the larger corallites, apparently destitute of tabulae, their 
 walls greatly thickened, and appearing on the surface as so 
 
292 TABULATE CORALS. 
 
 many detached spiniform processes placed at the angles of 
 junction of the larger tubes. Type of the group, Dekayia 
 aspera, E. and H. 
 
 III. CONSTELLARIA, Dana. Corallites of two kinds, the 
 larger ones circular or oval, with well-developed walls, which 
 become somewhat thickened as the calices are approached, the 
 tabulse being few in number and developed chiefly in the 
 outer portions of the corallum. Small corallites developed at 
 the angles of junction of the larger tubes, and more especi- 
 ally in the depressed centres of closely-disposed stellate areas, 
 which project above the general surface as conspicuous star- 
 shaped elevations. Walls of the small corallites imperfectly 
 developed, their shape being angular, or subangular, and their 
 tabulae being numerous and sometimes subvesicular. Type of 
 the group, Constellaria antheloidea, Hall. 
 
 IV. FISTULIPORA, M'Coy (= CALLOPORA, Hall). Corallites 
 of two kinds, the larger ones circular or oval, with few and 
 remote tabulae, but with well-developed walls, which are not 
 thickened towards the mouths. Small corallites completely 
 isolating the larger tubes, round which they are developed in 
 one or more rows, with numerous tabulae, which sometimes 
 become vesicular by imperfection of the walls of neighbouring 
 corallites. The shape of the smaller tubes is markedly angular 
 (sometimes round ?) ; and though they may be specially de- 
 veloped in star-like areas, these areas never project as stellate 
 elevations above the general surface. Type of the group, 
 Fistulipora minor ; M'Coy. 
 
 V. DIPLOTRYPA, Nich. Corallites of two kinds, the larger 
 ones thin - walled throughout, conspicuously polygonal, with 
 comparatively few and remote tabulae, which occasionally are 
 developed in a peculiar bilateral manner, so that the two halves 
 of the tube are provided with tabulae of a different kind and 
 form. The large corallites are usually or always aggregated 
 at special points into conspicuous clusters (" monticules "), but 
 they are at the same time scattered indiscriminately through 
 the entire colony, and except where forming the groups just 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^.. 293 
 
 alluded to, they are partially separated by the intervention of 
 the smaller corallites, which are always angular in shape, have 
 thin walls, are never so far developed as to completely isolate 
 all the larger tubes, and are always provided with more nu- 
 merous and more closely set tabulse than is the case in the 
 latter. Type of the group, Monticulipora petropolitana, 
 Pander. 
 
 VI. MONOTRYPA, Nich. Corallites of two kinds, which are 
 not conspicuously different from one another. The larger 
 tubes aggregated into clusters or " monticules," and very 
 slightly differing in size from the smaller ones. The smaller 
 tubes occupying all the spaces between the monticules. All 
 the corallites, of both kinds, uniformly thin-walled, regularly 
 polygonal, and similarly tabulate, the tabulse being remote and 
 few in number, and not uncommonly disposed at correspond- 
 ing levels in contiguous tubes. Type of the group, Monticuli- 
 pora (Chcetetes) und^ilata, Nich. 
 
 Sub-genus HETEROTRYPA, Nich., 1879. 
 
 This section includes many of the most typical and most 
 familiar of the species of Monticulipora, comprising among them 
 the M. mammulata, D'Orb., which, as the species first on the 
 list of Monticuliporce given by D'Orbigny (Prodr. de Paleont, 
 p. 25), has the right to be considered as the type of the whole 
 genus. In addition to M. mammulata, D'Orb., we must place 
 here M. ramosa, E. and H. (PI. XIII., figs. 2-2 a), M. rugosa, 
 E. and H., M. frondosa, D'Orb., M. Jamesi, Nich., M. monili- 
 formis, Nich., M. tumida, Phill., M. gracilis, James, and various 
 other more or less certainly established species. In all these 
 forms the corallum is conspicuously dimorphic (sometimes tri- 
 morphic), and consists of two sets of corallites of different sizes. 
 The larger tubes are subpolygonal or sometimes rounded in 
 shape, and are more or less conspicuously thickened towards 
 their mouths, while they usually possess few and remote 
 tabulae, or may be in great part devoid of these structures. 
 
294 TABULATE CORALS. 
 
 They are usually to some extent contiguous ; but they are 
 always partially separated by the corallites of the smaller series, 
 which are also subpolygonal or rounded, and more or less 
 thickened towards their mouths. Sometimes (as in M. fron- 
 dosa, D'Orb., M\ tumida, Phill., &c.) many of the smaller 
 corallites become abnormally thickened, so as to constitute a 
 third series, in which tabulae do not appear to be developed, 
 and which present themselves on the surface as a series of 
 blunt spines. In other cases whether or not spiniform coral- 
 lites are present the small corallites are more closely tabulate 
 than the larger ones, and are thus easily recognised in longi- 
 tudinal sections (PI. XIII., figs, i b and 2 a). The general 
 characters of the Monticuliporcz of this section will be best 
 understood from the following very brief descriptions of M. 
 mammulata, D'Orb., and M. ramosa, D'Orb. 
 
 Monticulipora (Heterotrypa) mammulata, D'Orb. 
 (PI. XIII. , figs, i - 1 b.) 
 
 Monticulipora mammulata, D'Orbigny, Prodr. de Paldont., t. i. p. 25, 1850. 
 Cfuztetes mammulatus, Edwards and Haime, Pol. Foss. des Terr. Pal., p. 267, 
 
 PI. XIX., fig. i, 1851. 
 Monticulipora mammulata, Edwards and Haime, Brit. Foss. Cor., p. 265, 
 
 1854- 
 Chcetetes mammulatus, Nicholson, Quart. Journ. Geol. Soc., vol. xxx. p. 508, 
 
 PL XXX., figs. 3 - 3 a, 1874 ; and Pal. of Ohio, vol. ii. p. 207, 1875. 
 
 Spec. Char. Corallum in the form of thin undulated expan- 
 sions, from two to four lines in thickness, consisting of two 
 layers of corallites, which diverge from an imaginary central 
 plane, to open on both sides of the frond. Surface covered 
 with well-marked " mamelons " placed at intervals of from half 
 a line to a line, and composed of corallites, which may be 
 slightly larger than the average, and which sometimes have 
 their calices closed by a calcareous membrane. Large or 
 average corallites polygonal, their walls but slightly thickened 
 towards their mouths, from eight to ten occupying the space of 
 one line. Small tubes not very numerous, wedged in among 
 
GENERA OF CH^TETID^E AND MONTICULIPORID&. 295 
 
 the larger corallites, and generally subpolygonal or angular in 
 shape. Large corallites with few and remote tabular ; small 
 corallites closely tabulate. 
 
 Obs. This species is so well known that I need only make 
 a few remarks upon its minute structure, as elucidated by thin 
 sections. Both tangential and vertical sections (the latter taken 
 at right angles to the plane of the frond) show that the coral- 
 lum is really dimorphic ; though the mere examination of the 
 surface with a lens, except in occasional specimens, would lead 
 one to conclude that small tubes are almost wanting. Tangen- 
 tial sections (PI. XIII., figs, i and i a) show, however, that 
 there exists really a fair number of small tubes scattered among 
 the larger corallites in an indiscriminate manner ; and vertical 
 sections (PI. XIII., fig. i d) prove that these are really special 
 corallites, as they are much more closely tabulate than the 
 ordinary corallites. There seems also generally to exist a very 
 small number of thickened spiniform tubes, easily recognised 
 in tangential sections by their circular outline and thick dark 
 margins ; though I have not been able to detect spines on the 
 surface. The corallites which occupy the " mamelons " cer- 
 tainly look a little larger, as a rule, than the average ; but as 
 they cannot be recognised in thin sections, I suspect this is an 
 illusory appearance, due to their greater nearness to the eye of 
 the observer. Their calices may be open, or may be closed by 
 a thin calcareous membrane, and they often have minute tubes 
 intercalated among them. The walls of the corallites, both 
 large and small, are slightly but unmistakably thickened by 
 a deposit of light-coloured sclerenchyma, which increases in 
 amount as the calices are approached (PI. XIII., fig. i a) ; but 
 in the limited extent of thickening, as well as in the compara- 
 tively small number of the smaller corallites, M. mammulata 
 shows itself to be not nearly such a characteristic member of 
 the section Heterotrypa as M. ramosa, D'Orb., M. frondosa, 
 D'Orb., M. Jamesi, Nich., or M. tumida, Phill. 
 
 Formation and Locality. Abundant in the Cincinnati group, 
 Cincinnati, Ohio. 
 
296 TABULATE CORALS. 
 
 Monticulipora (Heterotrypa) ramosa, Edwards and Haime. 
 (PI. XIII., figs. 2, 2 a.) 
 
 Monticulipora ramosa, D'Orbigny, Prodr. de Paleont., t. i. p. 25, 1850. 
 Chcetetes ramosus, Edwards and Haime, Pol. Foss. des Terr. Pal., p. 266, 
 
 PI. XIX., figS. 2, 2 a, 1851. 
 
 Monticulipora ramosa, Edwards and Haime, Brit. Foss. Cor., p. 265, 1854. 
 Chcetetes Dalei, Nicholson, Quart. Journ. Geol. Soc., vol. xxx. p. 501, PL 
 
 XXIX., figs, i, i a, 1874; Pal. of Ohio, vol. ii. p. 192, PI. XXI., figs. 
 
 i, i a, 1875. 
 Chatetes ramosus, Nicholson, Ann. Nat. Hist, ser. 4, vol. xviii. p. 88, 1876. 
 
 Spec. Char. Corallum dendroid, of cylindrical or elliptical 
 branches which divide dichotomously, and vary from one to 
 three or four lines in diameter. Corallites markedly divided into 
 two series, the larger ones being rounded or elliptical, about a 
 seventh or an eighth of a line in their long diameter, and open- 
 ing on the surface by subpolygonal calices, which have some- 
 what thickened margins. The small corallites are excessively 
 numerous, surrounding the larger tubes in a single row, and 
 often completely isolating them, their shape and size being very 
 variable. In internal structure, both sets of corallites are 
 traversed by complete horizontal tabular, which are much more 
 numerous in the small tubes than in the large ones. Walls 
 thickened towards the mouth. Surface covered with conical or 
 somewhat elongated " mamelons," placed at intervals of from 
 half a line to a line, and not occupied by corallites of specially 
 large or small dimensions. 
 
 Obs. The external characters of this species are too well 
 known to require further remark here ; but we may note the 
 following features in the intimate structure of the corallum, as 
 shown in thin sections. In thin tangential sections (PI. XIII., 
 fig. 2) the most striking appearance is the conspicuous division 
 of the corallites into two sets of tubes, large and small, and the 
 great development of the latter. The large tubes are very 
 uniform in size, generally oval or circular in shape, and mode- 
 rately thick-walled ; the thickening of the wall, however, never 
 
GENERA OF CH^ETETID^E AND MONTICULIPORIDsE. 297 
 
 proceeding to the extent that obtains in forms such as M. 
 (Heterotrypd) Jamesi, Nich., M. (Heterotrypa) tumida, Phill., 
 and allied types. The small corallites are very variable in 
 size and form, and are principally developed at the angles of 
 junction of the large tubes ; but they are commonly so numer- 
 ous as to form a complete zone round the large corallites, 
 though such a zone never consists of more than a single row. 
 Vertical sections (PI. XIII., fig. 2 a) show that the internal 
 structure of the large and small tubes is conspicuously different ; 
 both sets of corallites being traversed by complete horizontal 
 tabulae, which are greatly more numerous in the small tubes 
 than in the large ones. The " monticules " do not appear, as a 
 rule, to differ in structure from the general mass of the corallum, 
 but they seem sometimes to comprise a larger proportion of 
 small tubes than is usually the case in the intervening parts 
 of the skeleton. The internal structure of M. (Heterotrypa) 
 rugosa, E. and H., as I have elsewhere pointed out (Ann. Nat. 
 Hist, ser. 4, vol. xviii. p. 88), appears to be essentially the 
 same as that of M. ramosa, D'Orb. ; and the two are probably 
 but varietal forms of a single species. The only difference 
 between the two, in fact, is to be found in the marked trans- 
 verse elongation of the " monticules " of the former. 
 
 Formation and Locality. Common in the Cincinnati group, 
 Cincinnati, Ohio. 
 
 Sub-genus DEKAYIA, Edwards and Haime, 1851. 
 (Pol. Foss. des Terr. Pal., p. 277.) 
 
 This section of the genus Monticulipora includes only one 
 or two types, which were separated by Edwards and Haime as 
 a distinct genus under the name of Dekayia, but which I regard 
 as forming a group of no more than sub-generic value. In the 
 general nature and structure of the corallum the species of De- 
 kayia entirely resemble the dendroid forms of Monticulipora^ 
 and the only feature that would strike the observer is that the 
 
298 TABULATE CORALS, 
 
 surface of the former is studded with little quadrangular spines 
 or columns, interspersed in great numbers among the ordinary 
 tubes of the corallum. The structure of these columns was 
 first investigated by me by means of thin sections (Ann. Nat. 
 Hist., ser. 4, vol. xviii. p. 93, PI. V., figs. 12 and 12 a) ; but it 
 is only through more recent and more complete investigations 
 that I have been able to arrive at any definite conception as to 
 their real nature. I am, however, now satisfied that the coral- 
 lum in Dekayia is truly dimorphic, that the surface-columns are 
 the homologues of the spines which are so abundantly de- 
 veloped in M. (Heterotrypd) tumida, Phill., M. (Heterotrypa) 
 moniliformis, Nich., and other forms of Monticulipora, and 
 that these structures are properly to be regarded as a pecu- 
 liarly modified series of corallites. Taking this view of the 
 subject, the species of Dekayia are principally separable from 
 the spiniferous species of Monticulipora (Heterolrypd) by the 
 fact that in the former the spines are much reduced in number 
 and increased in size, while they are always isolated by the 
 large tubes, these latter being of one kind only. The more 
 minute characters of the sub-genus will appear from the follow- 
 ing very brief description of Dekayia attrita, Nich., the only 
 species with which I am acquainted, and which is very prob- 
 ably identical with the type-species D. aspera, E. and H. 
 
 Dekayia attrita, Nich. 
 (PI. XV., figs, i - i c.) 
 
 Chtztetes attritus, Nicholson, Quart. Journ. Geol. Soc., vol. xxx. p. 503, PI. 
 XXIX., figs. 4, 4 a, 1874; Pal. of Ohio, vol. ii. p. 194, PI. XXI., fig. 4, 
 
 1875- 
 
 Dekayia attrita, Nicholson, Ann. Nat. Hist, ser. 4, vol. xviii. p. 93, figs. 12, 
 12 a, 1876. 
 
 Spec. Char. Corallum dendroid, of subcylindrical branches, 
 varying from four to seven lines in diameter, and dividing at 
 short intervals. Corallites for the most part polygonal, thin- 
 walled, and sub-equal, from eight to ten in the space of one 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 299 
 
 line. Interspersed between the large corallites, generally at 
 the junction of four or six of the latter, are conical or sub- 
 quadrangular eminences or tubercles (PI. XV., fig. i a), 
 placed at intervals of from a fifth of a line to half a line. 
 These eminences are the upper ends of curved and thick- 
 walled tubes, which appear to be closed above, and which are 
 not traversed by tabulae, but which are to be regarded as 
 specially modified corallites. The normal corallites are crossed 
 by horizontal, complete, and remote tabulae. 
 
 Obs. This species seems to be distinct from D. aspera, 
 E. and H., its size apparently being less, and its form more 
 strictly dendroid ; but the latter is insufficiently described, and 
 it is quite possible that D. attrita is merely a variety of it. 
 In internal structure, tangential sections of D. attrita (PI. 
 XV., fig. i b) show that the bulk of the corallites are thin- 
 walled, polygonal, and approximately equal in size, while in- 
 terspersed among these and completely isolated by them are 
 the thick-walled tubes, which give rise to the surface-columns. 
 The apices of these columns (PI. XV., fig. i a) certainly seem 
 to be solid and imperforate ; but when divided transversely a 
 little below the surface, they are seen to be composed of dense 
 and dark-coloured sclerenchyma, deposited in successive con- 
 centric lamellae in the interior of the originally angular tube, 
 and almost always exhibiting a small circular central canal. 
 Tangential sections also show occasional small angular coral- 
 lites intercalated among the larger ones, and we may regard 
 these as spiniform corallites in which the walls are still un- 
 thickened. Vertical sections (PI. XV., fig. i c) show that the 
 corallum is mainly made up of the normal corallites, which in 
 the axis of the branches are provided with very delicate and 
 undulated walls, and are free from tabulae. As the corallites 
 curve outwards towards the surface, their walls become slightly 
 thickened, and a few remote and complete tabulae are developed 
 in their interior. The spines only extend inwards from the 
 surface to the point where the corallites bend downwards to 
 the axis of the branch, and they are seen to consist of a central 
 
300 TABULATE CORALS. 
 
 non-tabulate tube, bounded by very thick dense walls. In 
 some cases, also, the central tube of the spines seems to be 
 continued to the actual surface, though I have failed to detect 
 openings in the surface-columns. I have, however, no doubt 
 but that the surface-columns are primitively perforated, and 
 that the spines are, therefore, genuine corallites, though of a 
 peculiar kind. The forms to which Dekayia shows the greatest 
 affinity are those like Monticulipora (Heterotrypa) momliformis, 
 Mich., but in these the spiniform corallites are much more ex- 
 tensively developed. I must, however, defer further considera- 
 tion of this subject till I am able to separately discuss the very 
 remarkable features exhibited by the spines of various of the 
 Monticuliporoids, as well as of certain species of Stenopora. 
 
 Formation and Locality. Rare in the Cincinnati group, 
 Cincinnati, Ohio. 
 
 Sub-genus CONSTELLARIA, Dana, 1846. 
 
 (Zooph., p. 537, 1846.) 
 Stellipora, Hall, Pal. N.Y., vol. i. p. 79, 1847. 
 
 This section includes forms which, in many respects, are 
 very nearly allied to Fistulipora, M'Coy, but which exhibit 
 some very peculiar features. Some of the structural peculiari- 
 ties of the type will require for their elucidation much more 
 extended investigation than I have as yet been able to bestow 
 upon them, and the following must be regarded as little more 
 than a general and provisional statement as to the characters 
 of the sub-genus. The corallum in Constellaria is obviously 
 and conspicuously dimorphic, the most striking of its features 
 being the existence of a series of close-set, star-shaped, de- 
 pressed areas (" maculse"), which are occupied by the smaller 
 tubes, and which are surrounded each by a radiating circle of 
 short elevated ridges carrying large tubes (PI. XIV., fig. 5). 
 The large tubes also occupy, mainly or wholly, the spaces be- 
 tween the star-shaped monticules, and each is oval or circular 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 301 
 
 in shape, and surrounded by a strong and thickened wall, the 
 intervals between them being occupied by the smaller tubes. 
 The large corallites are traversed by a few remote tabulae, 
 and the small tubes are closely tabulate, their tabulae often be- 
 coming subvesicular, while their walls become obsolete. The 
 above characters will be more fully brought out by a brief 
 description of the type-species, the Constellaria antheloidea, 
 Hall, of the Lower Silurian of America. 
 
 Constellaria antheloidea, Hall. 
 (PI. XIV, figs. 5, S J.) 
 
 Stellipora antheloidea, Hall, Pal. N.Y., vol. i. p. 79, PI. XXVI., figs. 10 a, 
 
 10 c, 1847. 
 
 antheloidea, D'Orbigny, Prodr. de Paleont, t. i. p. 22, 1850. 
 
 Constellaria antheloidea, Edwards and Haime, Pol. Foss. des Terr. Pal., 
 
 p. 279, PI. XX., figs. 7 - 7 b, 1851. 
 
 antheloidea, Nicholson, Pal. of Ohio, vol. ii. p. 214, 1875. 
 
 ,, antheloidea, Nicholson, Ann. Nat. Hist., ser. 4, vol. xviii. p. 92, 
 
 PL V., fig. 10, 1876. 
 
 Spec. G&tfr. Corallum in the form of palmate, or sublobate, 
 flattened expansions, two or more inches in height, with a thick- 
 ness of from one and a half to two lines, and .composed of 
 corallites which radiate from an imaginary central plane to 
 open on all unattached parts of the skeleton. Surface (PI. 
 XIV., fig. 5) with numerous stellate areas, a line or less in 
 diameter, and placed about half a line or rather more apart, 
 each consisting of a depressed central space, surrounded by 
 from six to eight prominent and radiately - placed elevated 
 ridges. Corallites of two kinds, large and small. Large coral- 
 lites oval or circular, about one-tenth of a line in diameter, with 
 strong bounding-walls, occupying the general surface of the 
 corallum, and specially aggregated on the elevated ridges of 
 the star-shaped monticules, in the central depressed areas of 
 which they are wanting. Small tubes, apparently really sub- 
 angular, occupying all the interspaces between the larger oval 
 
3 o2 TABULATE CORALS. 
 
 tubes, and especially aggregated in the central depressed areas 
 of the monticules, and in the star-like prolongations which run 
 out from these ; their walls thin and apparently often wanting. 
 Large corallites with few remote tabulae ; small corallites with 
 very numerous close-set tabulae, which often anastomose with 
 those of neighbouring tubes. 
 
 Obs. Passing over the obvious and well - known external 
 features of the corallum in Constellaria antheloidea, I may 
 make a few remarks upon the appearances presented by thin 
 sections. Tangential sections (PI. XIV., fig. 5 a) present some 
 peculiar difficulties of preparation, owing to the irregularity of 
 the surface due to the monticules, but when properly made, 
 they are very instructive. They exhibit both sets of corallites, 
 the larger being conspicuous both by their size and their cir- 
 cular or oval form, and by the fact that each is bounded by a 
 thick and apparently double wall. It is only in the stellate 
 ridges of the monticules that the large corallites are at all ex- 
 tensively in contact ; but in the intervals between the monti- 
 cules they are only partially contiguous, and are separated 
 by more or less extensive interspaces. These interspaces, as 
 well as the central areas of the monticules and the branching 
 diverticula therefrom, are occupied by the smaller corallites. 
 The appearances presented by these vary under different cir- 
 cumstances, and in different parts of the section ; and I am not 
 at present able to explain some of the appearances which they 
 exhibit. They are best studied in the central depressed areas 
 of the monticules, and in their most perfect condition they are 
 seen to be angular in shape, and to be bounded by thin and 
 delicate walls, which, however, are often partially imperfect, 
 thus allowing neighbouring tubes to communicate. In other 
 cases, the divisional walls between the small corallites seem 
 wholly wanting, and the central areas of the monticules exhibit 
 simply minute rounded and remote pores, together with other 
 peculiarities which I must leave for future examination. In 
 the interspaces between the large tubes, also, the smaller tubes 
 only rarely seem to possess complete bounding walls, and here, 
 
GENERA OF CH&TETIDM AND MONTICULIPORID^E. 303 
 
 as in the monticules, there is the curious feature that the cavi- 
 ties of the smaller corallites seem to be very commonly obliter- 
 ated by a secondary deposit of light-coloured sclerenchyma. 
 Vertical sections (PI. XIV., fig. 5 b) render it certain, however, 
 that whether or not their walls are developed in a complete 
 form, the interspaces between the larger tubes and the central 
 areas of the monticules are alike uniformly occupied by the 
 smaller corallites. In sections of this kind, we see that the 
 large corallites exclusively occupy the central part of the cor- 
 allum, in which region they are thin-walled, and possess few or 
 sometimes no tabulae. As they bend outwards, in approaching 
 the surface, their walls become thicker, and the tabulae, though 
 still very few and widely remote, become somewhat more nu- 
 merous. The small corallites are only developed in the inter- 
 spaces between the larger tubes in the outer portion of the 
 course of the latter, so that they occupy only a superficial zone 
 of the corallum ; and they are at once recognised not only by 
 their small size, but also by their very numerous and close-set 
 tabulae. Sections of this kind further demonstrate that the 
 walls of the smaller tubes are really often wanting, though at 
 other times clearly recognisable ; their tabulae, in the former 
 case, becoming laterally coalescent and often more or less ex- 
 tensively vesicular. This latter feature is particularly observe 
 able in the aggregations of the smaller corallites which consti- 
 tute the central depressed areas of the monticules. 
 
 The affinities of Constellaria seem to be clearly with Fis~ 
 tulipora, M'Coy, in which, likewise, the bounding- walls of the 
 smaller tubes may in some forms become so far obsolete as to 
 allow of the tabulae assuming a completely vesicular structure. 
 The sub-genus is, however, sufficiently separated from Fistuli- 
 pora by the much less complete development of the small tubes, 
 which in the latter type always completely encircle and isolate 
 the larger tubes ; while the star-shaped form of the monticules 
 is another well-marked distinguishing character. 
 
 Formation and Locality. Rare in the Cincinnati group, 
 Cincinnati, Ohio. 
 
3 o 4 TABULATE CORALS. 
 
 Sub-genus FISTULIPORA, M'Coy, 1849. 
 
 (Ann. and Mag. Nat. Hist., ser. 2, vol. iii. p. 130.) 
 
 Callopora, Hall. Pal. N.Y., vol. ii. p. 144, 1852. 
 
 The corals of this group were separated by M'Coy to form 
 his genus Fistulipora, with the following generic diagnosis : 
 
 " Corallum encrusting, composed of long, simple, cylindrical, 
 thick-walled tubes, the mouths of which open as simple, equal, 
 circular cells on the surface, and having transverse funnel- 
 shaped diaphragms at variable distances ; interval between 
 the tubes occupied by a cellular network of small vesicular 
 plates." The type of the genus- is the F. minor, M'Coy, of 
 the Carboniferous Limestone of Derbyshire. 
 
 At a later period, Professor Hall proposed the name of 
 Callopora for certain Upper Silurian corals, with the following 
 generic diagnosis : 
 
 " Ramose or encrusting species of corals, having a columnar 
 structure ; cells tubular, with the apertures circular or petaloid, 
 not contiguous, and having the intermediate spaces occupied 
 by angular cell-like openings which are transversely septate ; 
 tubular cells rarely septate." 
 
 The identity of Fistulipora, M'Coy, and Callopora, Hall, 
 has long been more than suspected, the chief difficulty in the 
 way of uniting the two being that M'Coy states that the tabulae 
 in the large corallites of Fistulipora have infundibuliform 
 tabulae, while Hall describes radiating septa as sometimes 
 present in the type-species of Callopora. M 'Coy's statement 
 as to the tabulae is, however, clearly based upon imperfect 
 observation, and this is also almost certainly the case as to the 
 alleged occurrence of septa. At any rate, having carefully 
 examined specimens of F. minor, M'Coy, the type of the genus 
 Fistulipora, and having compared these with typical examples 
 of Hall's genus Callopora from the Silurian and Devonian 
 rocks of North America, I am satisfied that the two are un- 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 305 
 
 questionably congeneric, and that both must be united under 
 the older name of Fistulipora, M'Coy. The intimate structure 
 of the genus is also so nearly allied to that of certain Monti- 
 culiporte, as well as to Constellaria, that I think it is best to 
 regard Fistulipora as only a sub-genus of Monticulipora. 
 
 The species of Fistulipora agree in the possession of a 
 dimorphic coral'lum, composed of two sets of corallites of con- 
 spicuously different sizes, and bearing definite relations to one 
 another. The large corallites are markedly circular or oval, 
 in most forms, and are isolated in position, while their cavities 
 are intersected by few and remote horizontal tabulae, these 
 structures being occasionally partially absent. The smaller 
 corallites are distinctly angular in form, and surround the 
 larger tubes completely, there being sometimes one and some- 
 times two rows between any given pair of the latter. The smaller 
 corallites are furnished with numerous and close-set tabulae, and 
 may or may not be bounded by complete walls. In the former 
 case the tabulae are complete and horizontal, whereas in the 
 latter case they anastomose with one another, and give rise to 
 a tissue of convex lenticular vesicles, the variations observable 
 in this respect being precisely parallel with those which obtain 
 respectively in Heliolites and Propora. The walls of the cor- 
 allites of both sets are thin, and are not conspicuously thickened 
 towards their mouths. It should also be borne in mind that 
 the interstitial and closely-tabulate corallites are sometimes 
 equal in size to the round and remotely-tabulate corallites which 
 they surround ; so that in speaking of the former as the " small " 
 corallites, we only employ this term in a conventional sense, 
 as indicating their homology with the small tubes of the Mon- 
 ticuliporoids generally. The corallum in Fistulipora often 
 exhibits " maculae " or definite areas occupied by the smaller 
 corallites only. These maculae may be stellate in shape ; but 
 they are never elevated above the surface or surrounded by 
 radiating elevated ridges, as is the case in Constellaria. Lastly 
 while the large rounded tubes always open the surface by open 
 calices, the intermediate angular tubes often have their mouths 
 
 u 
 
306 TABULATE CORALS. 
 
 closed in the adult condition by a thin calcareous membrane. 
 In no case are septa present. 
 
 From the Heliolitidcz, Fistulipora is separated mainly by the 
 total absence of septa in the latter ; but, as has been pointed 
 out, there is a striking resemblance in general structure between 
 certain species of Fistulipora, on the one hand, and the species 
 of Propora and Heliolites on the other hand. " Mural pores " 
 have not been detected in any typical form of Fistulipora ; but, 
 as has been previously mentioned, Dr Rominger has shown 
 (Foss. Cor. of Mich., p. 29) that the coral described by Mr 
 Billings from the Devonian of Canada, under the name of 
 Fistulipora Canadensis, is provided with perforate walls, and is 
 therefore a genuine Favositoid type. We thus have a coral 
 which precisely resembles the normal forms of Fistulipora in 
 appearance, but which exhibits mural pores ; and it becomes, 
 therefore, a matter for future research whether or not these 
 structures occur in any other species now referred to Fistulipora. 
 
 The genus Fistulipora ranges from the Silurian to the Car- 
 boniferous, and I shall briefly describe the following three 
 species as illustrating its more characteristic features. 
 
 Fistulipora minor, M'Coy. 
 
 Fistulipora minor, M'Coy, Ann. Nat. Hist, ser. 2, vol. iii. p. 130, 1849; 
 and Brit. Pal. Foss., p. 79, 1851. 
 
 Spec. Char. Corallum in the form of thin, irregular crusts, 
 attached parasitically at one point or over the whole lower sur- 
 face, attaining a thickness of two or three lines. Large corallites 
 oval or circular, about a fifth of a line in their long diameter; 
 separated by interspaces of about their own width, less or 
 more ; and with few or no tabulae, these structures, when pres- 
 ent, being horizontal. Small tubes angular, of variable shape, 
 generally about a tenth of a line in diameter, each of the larger 
 tubes being surrounded by a single circle of the smaller coral- 
 lites, so that there exist two rows of the latter between any 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^. 307 
 
 given pair of the former. The small tubes are closely tabulate, 
 but by the imperfect development of their walls the tabulae 
 coalesce to a larger or smaller extent, and thus give rise to a 
 vesicular tissue, composed of lenticular vesicles, which have their 
 convexities directed upwards. 
 
 Fig. 39. Fistulipora minor, M'Coy. A, Portion of a tangential section, showing the rounded 
 large tubes (a, a) and the angular interstitial tubes (b, b); B, Portion of a vertical section, 
 showing two of the large tubes, almost free from tabulae (a, a), and the interstitial vesicular 
 tissue formed by the tabulae of the smaller tubes (b, b). The sections are enlarged twenty- 
 five times. 
 
 Obs. I am indebted to my friend Dr Ramsay H. Traquair 
 for a specimen from the Carboniferous rocks of Scotland which 
 he had previously, and unquestionably correctly, identified with 
 the Fistulipora minor of M'Coy. The surface of this specimen 
 is poorly preserved, the prominent round mouths of the larger 
 tubes being alone shown ; and I am unable to determine 
 whether or not " maculae " are present, though I see no traces 
 of these in thin sections. The internal structure is fully shown 
 by thin tangential and vertical sections (fig. 39, A and B) ; but I 
 need add nothing further to the description given in the specific 
 diagnosis. 
 
 In its minute characters, F. minor is nearly related to F. 
 incrassata, Nich., from the- Devonian of North America. This 
 
3 o8 TABULATE CORALS. 
 
 is especially shown by the fact that the tabulae of the angular 
 corallites in both species give rise to a series of convex lentic- 
 ular vesicles (compare fig. 39, B, and PI. XV., fig. 3 b). The 
 large round corallites of F. incrassata are, however, nearly 
 twice as large as those of F. minor, and are only separated by 
 a single row of angular tubes, while they are provided with 
 more numerous tabulse, these features alone being sufficient to 
 establish the specific distinctness of the two forms. 
 
 Formation and Locality. In the Lower Carboniferous Lime- 
 stone of Cousland, near Edinburgh. Collected by Dr R. H. 
 Traquair. 
 
 Fistulipora incrassata, Nich. 
 (PI. XV., figs. 3-3*) 
 
 Callopora incrassata, Nicholson, Geol. Mag., Dec. ii. vol. i. p. 13, PI. II., fig. i, 
 1874; Rep. Pal. of Ontario, p. 61, fig. 19, 1875. 
 
 Spec. Char. Corallum sometimes forming thin crusts, at- 
 tached parasitically to foreign bodies, or partially epithecate 
 below, or at other times constituting irregular masses of con- 
 siderable size. Large corallites, oval or pyriform in section, 
 one end being wider than the other, and the junction between 
 the two commonly being marked by two small laminar inflec- 
 tions of the wall of the tube on opposite sides. The large 
 tubes are about a third of a line in their long diameter, and 
 their calices project slightly above the general surface, while 
 they are completely separated from one another by the inter- 
 mediate " small " corallites. These latter are angular in form, 
 and there is never more than a single row of them between any 
 given pair of the large corallites. Their mouths are seldom dis- 
 tinctly shown, and are often closed by a thin calcareous mem- 
 brane. At intervals the surface shows star-shaped depressed 
 "maculae," which are entirely occupied by the angular coral- 
 lites, and which are often covered by a superficial calcareous 
 pellicle. Owing to the variable shape of the angular corallites, 
 
GENERA OF CH^TETID^E AND MONTICULIPORID&. 309 
 
 their size is correspondingly variable ; but they are generally 
 of smaller diameter than the round tubes. The large corallites 
 are intersected by a few, remote, horizontal tabulse ; while the 
 tabulae of the angular interstitial corallites are much more 
 closely set, and become amalgamated in contiguous tubes, so 
 as to give rise to a vesicular tissue, the lenticular vesicles of 
 which have their convexities directed upwards. 
 
 Obs. I have reproduced here the original figures of this 
 species (fig. 40), though they are in some respects incorrect. 
 The real structure of the 
 corallum is, however, shown 
 in PI. XV., figs. 3 - 3 d, from 
 which it will be seen that 
 its minute characters are in 
 the main similar to those of 
 Fistulipora minor, M'Coy. 
 It differs from this form, 
 however, in the larger size 
 of the round corallites, and 
 in the fact that any given 
 two of these are separated 
 by no more than one row 
 of the smaller tubes. Not 
 only are these latter mark- 
 edly angular in shape, but 
 
 xv* 
 
 Fig. 40. Fistulipora incrassata, Nich. a, A 
 fragment, of the natural size ; b, A portion of 
 the surface enlarged, showing the mouths of 
 the two sets of corallites ; c, A portion of the 
 surface less highly magnified, showing one of 
 the star-shaped "maculae;" d, Vertical sec- 
 tion enlarged. 
 
 they, thus, necessarily abut 
 
 on their opposite sides against the larger corallites. The large 
 tubes are not only oval, but they are wider at one end than the 
 other, and they usually exhibit the peculiar feature that there 
 exist two small inward inflections of the wall of the tube, which 
 are placed, one on each side, at a point situated about one-third 
 of the long diameter of the tube from its pointed end (PI. XV., 
 fig. 3 a}. Thin vertical sections (PI. XV., fig. 3 b) show that 
 the large corallites are intersected by a few complete horizontal 
 tabulse ; while the walls of the smaller tubes are imperfectly 
 developed, and their tabulae coalesce to constitute a series of 
 
3IO TABULATE CORALS. 
 
 strongly convex vesicles. From the nearly allied F. proporoides, 
 Nich., the present species is distinguished by its generally more 
 massive form, the inflections of the walls of the large corallites 
 above spoken of, and the fact that the tabulae of the smaller 
 tubes coalesce to form a vesicular tissue. 
 
 Formation and Locality. Common in the Hamilton Group 
 of Arkona, Ontario. I originally included under the name of 
 Callopora incrassata certain large and massive specimens from 
 the Corniferous Limestone of Ontario. Not having had, how- 
 ever, the opportunity of examining these microscopically, I do 
 not feel sure they are specifically identical with the Hamilton 
 examples, upon the characters of which the foregoing descrip- 
 tion is based. 
 
 Fistulipora proporoides, Nich. 
 (Fig. 41, and PI. XV., figs. 2, 2 a.) 
 
 Spec. Char. Corallum in the form of thin and extended, 
 often much contorted expansions, which have an average thick- 
 ness of about one line, and have the under surface covered by 
 a concentrically -striated epitheca, the corallites being nearly 
 vertical, and opening upon the upper surface. The large coral- 
 lites are oval or nearly circular, about one-fifth or one-sixth of 
 a line in diameter, and separated by interspaces of about the 
 same width. The " small " corallites are markedly angular, 
 only one row ever existing between contiguous round tubes, 
 and their size being often equal to, or even larger than, that of 
 the latter. On the surface the calices of the round tubes 
 appear as marked projecting apertures, while the calices of the 
 angular tubes appear to be usually closed in the adult condition 
 by a thin calcareous membrane. Maculae present or absent. 
 In internal structure the round tubes have very few or no 
 tabulae, and, when present, these structures are always com- 
 plete and horizontal. The " small " tubes are always bounded 
 by complete walls, and are intersected by comparatively 
 numerous horizontal, not vesicular tabulae. 
 
GENERA OF CH^TETID^. AND MONTICULIPORID^E. 311 
 
 Obs. This beautiful species, in the essential features of its 
 organisation, is clearly nearly allied to the two forms previously 
 described, and especially to F. incrassata. It agrees more 
 particularly with this last in the comparatively large size and 
 markedly angular form of the interstitial corallites, and in the 
 fact that there is but one single series of these separating the 
 round tubes. In both species also the surface exhibits, alone 
 or principally, the projecting apertures of the round corallites 
 (PI. XV., figs. 2 and 2 a), the mouths of the angular intersti- 
 tial tubes seeming to be often closed by a thin calcareous mem- 
 brane. The form of the corallum, however, is in the present 
 species always that of a thin, often contorted expansion, the 
 under surface of which is clothed by a striated and plicated 
 
 Fig. 41. Fistulipora proporoides, Nich. A, Part of a vertical section, enlarged twenty times, 
 showing the different tabulation of the two sets of corallites. B, Part of a tangential 
 section, showing the round and the angular corallites, enlarged twenty times : a, a, Round 
 or "large" corallites ; b, b, Angular or " small " corallites. 
 
 epitheca ; the round corallites are strictly round or oval, and 
 are not contracted at one point ; the " maculae " are sometimes 
 obsolete ; and there is the striking internal difference that the 
 angular interstitial corallites are always limited by complete 
 walls, and are intersected by numerous horizontal tabulae, which 
 never assume a vesicular character (Fig. 41, A). This last- 
 mentioned feature, among other points of distinction, sufficiently 
 
3 i2 TABULATE CORALS. 
 
 separates the species from F. minor, M'Coy, this latter like- 
 wise having a much greater development of the interstitial 
 corallites. 
 
 Formation and Locality. Common in the Hamilton Group, 
 Canandaigua, State of New York. 
 
 Sub-genus DIPLOTRYPA, Nich., 1879. 
 
 I propose this name as a subgeneric designation for a group 
 of Monticulipora, of which M. petropolitana, Pand., is the 
 type. The corallum in the forms in question is like that of 
 the sub-genus Heterotrypa in being conspicuously dimorphic ; 
 but all the corallites are markedly angular or prismatic, while 
 their walls are remarkably thin and delicate, and their general 
 appearance resembles that of the corallites of Favosites. The 
 large corallites have few and remote tabulae, and are usually or 
 always aggregated at special points into clusters or " monti- 
 cules ; " but they are also scattered throughout the entire 
 colony, the bulk of which they compose. In the "monticules" 
 the large tubes are usually alone present, but in the other parts 
 of the corallum the larger corallites are partially separated by 
 the development of a larger or smaller number of small coral- 
 lites, which agree with the large ones in being angular in shape, 
 but differ in being provided with much more numerous and 
 close-set tabulae. The characters of the group will be best 
 elucidated by a brief consideration of the internal structure of 
 M. (Diplotrypa) petropolitana, Pand. 
 
GENERA OF CH&TETTD& AND MONTICULIPORID^. 313 
 
 Monticulipora (Diplotrypa) petropolitana, Pander. 
 (PL XIII., figs. 3- 3 r.) 
 
 Favosites petropolitanus, Pander, Russ. Reiche, p. 105, PI. I., figs. 6, 7, 10, n, 
 1830. 
 
 (Non Chatetes petropolitanus, Nicholson, Quart. Journ. Geol. Soc., vol. xxx. 
 p. 510, PI. XXX., figs. 5-8, 1874; Geol. Mag. Dec. ii., vol. ii. p. 175, 
 1875; Pal. Ohio, vol. ii. p. 204, PI. XXI., figs. 14-14 &, 1 %T5 '> Ann - 
 Nat. Hist., ser. 4, vol. xviii. p. 88, PI. V., figs. 6 - 6 a.) x 
 
 Spec. Char. Corallum discoid when young, but spheroidal, 
 or hemispherical when fully grown, the base being circular, 
 more or less deeply concave, and covered with a concentrically 
 striated epitheca, while the calices cover the whole of the upper 
 surface. The corallites are of two sizes, large and small, these 
 being uniformly interspersed with one another throughout the 
 entire colony, while the former also constitute small clusters or 
 monticules. The large corallites are about one-quarter of a 
 line in diameter, provided with uniformly thin and delicate 
 walls, not thickened towards the surface, and for the most part 
 very regularly hexagonal in shape. The small corallites are 
 wedged in at the angles of junction of the large tubes, which 
 they sometimes to a large extent separate from one another, 
 their diameter varying from a twelfth to an eighth of a line or 
 more. They resemble the large corallites in being uniformly 
 thin-walled and strictly angular, their shape being very variable, 
 but mostly oblong, square, or sub-triangular. Both sets of 
 tubes are provided with complete horizontal tabulse, which 
 increase in number towards the surface ; and the tabulae in the 
 smaller tubes are more numerous than in the larger ones, 
 though this disproportion is not so marked as is usually the 
 case in the species of Monticulipora. 
 
 Obs. A great number of corals have been described or 
 quoted by different authors from the Lower Silurian deposits of 
 
 1 Beyond pointing out that the forms which I have previously considered and 
 described as M. petropolitana, Pand., are really distinct from the original Russian 
 type of the species, I have not thought it for reasons to be subsequently given of 
 any use to attempt to give a synonymy of this form. 
 
3 i4 - TABULATE CORALS. 
 
 different parts of the world under the name of Monticulipora 
 petropolitana or Chcetetes petropolitanus, Pand. In most cases, 
 however, the determination of particular specimens as belong- 
 ing to this species has been founded upon the well-marked 
 external form of the corallum and the general nature, often 
 with difficulty recognisable, of its surface characters. That 
 this should be the case was inevitable, seeing that the internal 
 structure of the corallum does not admit of being made out 
 properly save by means of carefully-prepared sections ; and, 
 further, that the minute characters of the genuine Russian types 
 of the species have never been, so far as I am aware, either 
 described or figured. Even now it can hardly be said that the 
 position of our knowledge is absolutely satisfactory, seeing that 
 Pander's type-specimens have not been subjected to minute 
 examination. I am, however, indebted to the kindness of my 
 friend Dr Lindstrom for specimens from the Lower Silurian 
 of Sweden, the identity of which with the original Favosites 
 petropolitanus of Pander hardly admits of doubt, seeing that 
 they are derived from a corresponding geological horizon and 
 from a neighbouring geographical area. These specimens I 
 have subjected to a careful microscopic examination, and the 
 characters which they afford I regard as those specifically 
 diagnostic of M. petropolitana, Pand. Starting with this basis, 
 it is at once clear .that the mere external form and surface- 
 characters of the corallum are of no use at all in the deter- 
 mination of this species. Thus all, or almost all, of the corals 
 which I have myself examined and described from the Lower 
 Silurian rocks of North America, and which I have identified 
 with M. petropolitana on account of their general form and 
 appearance, turn out to be widely different from the similar- 
 looking Russian species in their internal structure. I shall 
 also describe specimens from the Devonian which on merely 
 external examination would unhesitatingly be referred to M. 
 petropolitana , but which, tested by the facts of their minute 
 structure, are specifically or even sub - generically different. 
 Considering, therefore, that almost all the determinations of 
 
GENERA OF CH&TETID& AND MONTICULIPORID^. 315 
 
 M. petropolitana, in different deposits and in different countries, 
 have been based solely upon macroscopic investigation, and 
 that this is clearly insufficient for specific diagnosis, it has ap- 
 peared to me to be quite useless to give any synonymy of the 
 species. With our present knowledge, in fact, such a synonymy 
 would simply give us the information that certain authors had 
 identified from certain regions and formations corals which are 
 doubtless referable to Monticulipora, in its wide sense, and 
 which resemble M. petropolitana in form and habit. 
 
 In the Swedish specimens of M. petropolitana, Pand., which 
 I shall take as the type of the species, the corallum has the 
 well-known hemispherical or sub-globular form, its circular and 
 concave base being covered with a thin concentrically striated 
 epitheca (PI. XIII., figs. 3, 3 a). In thin sections (PI. XIII., 
 figs. 3 b and 3 c) no feature is more striking than the ex- 
 treme delicacy and tenuity of the walls of all the coral- 
 lites. The walls are so thin that they appear as mere simple 
 and undivided dark lines, the originally duplex character of 
 the boundaries between contiguous corallites being entirely 
 lost. Nor, again, do the walls become in any way thickened 
 as the surface is approached. In this respect, therefore, there 
 is a marked and important difference in the structure of this 
 form as compared with the more normal types of Monticuli- 
 pora (Heterotrypa). In tangential sections (PI. XIII., fig. 3 6) 
 another marked peculiarity is the strictly angular form of all 
 the tubes, and the very regularly hexagonal or pentagonal 
 outline of the larger corallites. Each of the larger tubes is 
 usually in contact with a tube of the same series on one or 
 two sides, but the other faces usually abut against corallites of 
 the smaller series, these being generally oblong or quadrate 
 in shape. In vertical sections (PI. XIII., fig. 3 c) the two 
 sets of corallites are chiefly recognisable by the difference in 
 their respective sizes, their tabulation being more uniform 
 than is usual in the genus. The small corallites are, however, 
 always to some extent more closely tabulate than is the case 
 with the large tubes. 
 
316 TABULATE CORALS. 
 
 The nearest ally of M. (Diplotrypa) petropolitana with which 
 I am acquainted is one of the forms which I previously de- 
 scribed as Chcetetes petropolitanus, from the Lower Silurian 
 rocks of North America. Now, however, that I know the 
 internal structure of the Russian species, I find that the 
 American specimens are specifically distinct, and I shall de- 
 scribe them under the name of M, (Diplotrypa) Whiteavesii. 
 They are distinguished from M. petropolitana, Pand., by the 
 much closer tabulation of the small corallites, the peculiar 
 double tabulation of many of the large corallites, and the 
 form and size of the latter tubes. From the forms which I 
 shall here describe under the names of M. (Monotrypa) un- 
 dulata, and M. (Monotrypa) Winteri, the present species is 
 easily distinguished on minute examination ; for both the 
 former types are destitute of a series of small corallites 
 interspersed among the ordinary tubes of the colony, while 
 all the corallites are similarly and uniformly tabulate. 
 
 Formation and Locality. Lower Silurian (Chasmops Lime- 
 stone), Ostragothia, Sweden. Collected by Dr Lindstrom. 
 
 Monticulipora (Diplotrypa) Whiteavesii, Nich. 
 (PI. XIIL, figs. 4-4 b, and PL XIV., fig. i.) 
 
 Chatetes petropolitanus, Nicholson, Quart. Journ. Geol Soc., vol. xxx. p. 510, 
 
 PI. XXX., figs. 5 - 8, 1875. 
 petropolitanus (pars), Nicholson, Pal. of Ohio, vol. ii. p. 204, PI. XXI., 
 
 figs. 14, 14 b, 1875. 
 petropolitanus, Nicholson, Ann. Nat. Hist., ser. 4, vol. xviii. p. 88, PI. 
 
 V., figs. 6, 6 a, 1876. 
 petropolitanus (pars), Nicholson, Geol. Mag. Dec. ii., vol. ii. p. 175, 
 
 1875. 
 petropolitanus, Nicholson, Rep. Pal. of Ontario, p. 10, PI. IV., figs. 3 
 
 and 4, 1875. 
 
 Spec. Char. Corallum discoid when young, hemispheric 
 when adult, often with the lateral margins widely extended, 
 the base being usually deeply concave, sometimes flattened, 
 and being covered by a concentrically striated epithecal plate. 
 
GENERA OF CH^ETETID^E AND MONTICULIPORIDsE. 317 
 
 Corallites directed upwards nearly at right angles to the entire 
 basal plate, and opening upon the upper aspect of the colony. 
 Surface with scattered and very slightly raised " monticules " 
 composed of corallites slightly above the average in size. 
 Corallites of two kinds, large and small, the tubes of both 
 series intermingled throughout the entire corallum. Large 
 tubes, mostly from a sixth to a fifth of a line in diameter, 
 more or less thin-walled, angular, often hexagonal, in shape, 
 and sometimes arranged in small groups or rosettes of four 
 or five tubes each. Small corallites very numerous and very 
 variable in size and form, but always thin-walled and angular, 
 and wedged into all the interspaces left between the large 
 tubes. In internal structure the large tubes may be simply 
 crossed by remote, delicate, complete tabulae ; but many of 
 them are divided by a vertical flexuous partition into two 
 compartments, the tabulae on the one side of this partition 
 being strongly curved, with their convexities directed up- 
 wards, while on the other side they are simply horizontal. 
 In the small tubes the tabulae are always very numerous, 
 close-set, and horizontal. 
 
 (9fo. In general form, the corallum of the present species 
 (fig. 42, and PI. XIII., figs. 4, 4 a) is generally quite like that 
 
 Fig. 42. Monticulipora (Diplotrypa) Whiteavesii. A, Side view of the corallum, of the natural 
 size ; B, Transverse section of the corallum near its base, showing the thin-walled hex- 
 agonal corallites, enlarged. (This section cuts across the axial corallites close above their 
 origin, showing none of the small tubes, the appearances presented being thus quite unlike 
 those exhibited by a tangential section taken just below the surface, as in PI. XIII.. fig. 
 4 b) ; c, Part of a vertical section, greatly enlarged. 
 
 of the typical M. petropolitana, Pand., with which it has gener- 
 ally been confounded by myself and others. When young it is 
 a concavo-convex disc ; but it usually becomes elevated and 
 
3i8 TABULATE CORALS. 
 
 hemispherical when fully grown. The lateral margins of the 
 corallum are, however, very often extended and comparatively 
 thin, the chief elevation of the corallum being central, and there 
 is often a curious funnel-shaped depression at the summit of the 
 colony, the nature of which I do not understand. Adult coralla 
 reach a diameter of from one and a half to three inches, with a 
 height of three-quarters of an inch to an inch. The characters 
 of the surface are very like those of the typical M. petropolitana, 
 Pand., especially in the presence of low elevations or monticules, 
 composed of corallites which seem to be slightly larger than the 
 average. Thin sections show that the corallum also, as in M. 
 petropolitana, is composed of very thin -walled corallites, the 
 walls of which are undistinguishably united, and are not thick- 
 ened towards the surface ; while two distinct sets of tubes, of 
 different sizes, form by their intermixture the entire colony. 
 Tangential sections (PI. XIII., fig. 4 b) clearly exhibit both 
 groups of corallites, both being angular in shape, and the 
 small tubes being situated at all the angles left between the 
 larger ones. The latter are seldom completely surrounded 
 by small tubes, though this does sometimes occur. Very 
 characteristically the large tubes are arranged in stellate 
 groups or rosettes, consisting of four or five tubes ; and 
 the central point where these meet is marked by a thick- 
 ened rounded or quadrate body, which exhibits commonly a 
 median tube. Similar structures are often developed at the 
 points where the small corallites abut against the larger ones, 
 and their appearance is precisely similar to that of the 
 " columns " of Dekayia, or the spines of certain of the Monti- 
 culiporcz as seen in transverse section. I cannot say, however, 
 that I have ever detected spines on the surface in this species, 
 though I cannot doubt that the structures to which I have just 
 referred are peculiarly modified corallites. Vertical sections 
 (PL XIV., fig. i) show that the corallites, instead of being 
 reclined towards the margin of the colony, are everywhere 
 nearly perpendicular to the epithecal plate ; and they further 
 show very striking differences in the structure of the large 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 319 
 
 and small tubes. The former are not uniformly similar in 
 structure. In some cases they are simply crossed by a few 
 remote tabulae, as is usual among the Monticulipora. In 
 other cases, and more commonly, however, they exhibit 
 throughout or in part of their course a very singular double 
 arrangement of the tabulse, the explanation of the phenomena 
 in question being still unknown to me. In these cases the visc- 
 eral chamber of the corallite may be considered as divided into 
 two lateral halves or compartments. In one half of the tube 
 the tabulae are not only remote, but are strongly convex, with 
 their convexities directed upwards, or towards the centre of 
 the visceral chamber, thus forming a series of large lenticular 
 vesicles, the internal margins of which unite so as to form an 
 apparent median septum to the tube. In the other half of the 
 corallite the tabulae are simply remote, complete, and horizontal, 
 extending from the lateral wall of the corallite on the one hand 
 to the inner margin of the lenticular vesicles just mentioned on 
 the other hand. Lastly, the smaller corallites are uniformly 
 provided with very numerous crowded and complete horizontal 
 tabulae. 
 
 The features which separate M. (Diplotrypci) Whiteavesii, 
 Nich., from the typical M. petropolitana, Pand., have been 
 alluded to in speaking of the latter, and need not be further 
 insisted on here. The internal structure of the corallum, and 
 especially the remarkable form of tabulation displayed by the 
 greater number of the large corallites, will serve to differen- 
 tiate the species from all other types which resemble it in 
 general shape and aspect. 
 
 I have named the species after my friend Mr Whiteaves, 
 the accomplished palaeontologist of the Canadian Geological 
 Survey. 
 
 Formation and Locality.- Abundant in the Trenton Lime- 
 stone of Peterboro', and of other localities in Ontario. 
 Specimens of a rounded form attached by a broad base to 
 foreign bodies occur also in the Cincinnati group of Waynes- 
 ville, Ohio. 
 
3 2o TABULATE CORALS, 
 
 Sub-genus MONOTRYPA, Nicholson, 1879. 
 
 I propose the name of Monotrypa for a few forms of Monti- 
 culipora which agree with those that I have called Diplotrypa 
 in the fact that the corallites are thin-walled throughout their 
 entire extent, and are so amalgamated in contiguous tubes that 
 their originally double structure is not recognisable. On the 
 other hand, they differ from Diplotrypa in the fact that the 
 closely-tabulate small corallites of the latter are now totally 
 absent, the colony consisting of subequal tubes which are uni- 
 formly and throughout provided with remote and complete 
 tabulae. The only sign of dimorphism, in fact, which can be 
 detected in the corallum of Monotrypa is the constant existence 
 of special clusters (" monticules ") of corallites, which are de- 
 cidedly larger than the average tubes, though quite like these 
 in internal structure. 
 
 There are several respects in which this section of the genus 
 Monticulipora must be considered as not wholly satisfactory, at 
 the same time that the composition of the corallum out of tubes 
 which are identical in internal structure, and which differ very 
 little in point of size, precludes our associating the forms in 
 question with any of those we have been previously considering. 
 In some points Monotrypa makes an approach to Chcetetes 
 proper, but the much greater thinness of the walls of the coral- 
 lites, and the constant presence of clusters of large tubes, suffi- 
 ciently distinguish the species of the former from those of the 
 latter. The only two forms which I at present know as com- 
 bining all the features here ascribed to Monotrypa are those 
 which I shall describe immediately under the name of M. un- 
 dulata and M. Winteri. Typical examples of the M. pulchella, 
 E. and H., from the Upper Silurian of Britain, show, however, 
 all the general characters of Monotrypa (see PI. XIV., figs. 
 6, 6 a), except that the walls of the corallites become decidedly 
 thickened in approaching the surface, and the boundary-lines 
 between contiguous tubes are usually clearly marked. (I have 
 
GENERA OF CHsETETID^ AND MONTICULIPORID^E. 321 
 
 not yet submitted to microscopic examination the forms from 
 the Lower Silurian rocks of North America which have usually 
 been known to American palaeontologists as M. pulchella or 
 Ch&tetes pulchellus ; but I suspect they will prove to be distinct 
 from the British Upper Silurian examples, which are the true 
 type of the species). 
 
 Monticulipora (Monotrypa) undulata, Nich. 
 (PI. XIV., figs. 3 - 3 , and 4 - 4 a.} 
 
 Chcetetes undulatus, Nicholson, Geol. Mag., Dec. ii. vol. ii. p. 176, 1875. 
 undulatus, Nicholson, Rep. on the Pal. of Ontario, 1875, PP- I0 > 33? 
 PL IV., fig. i. 
 
 Spec. Char, Corallum forming large lobed or laterally in- 
 dented masses, or occurring as smaller hemispherical or spher- 
 oidal masses, of from half an inch to more than an inch in 
 diameter. Corallites uniformly thin - walled, angular, and 
 prismatic in shape, sub-equal in size, varying from one-fifth or 
 one-sixth of a line up to a quarter of a line or rather more. 
 The bulk of the corallum is made up of corallites of the smaller 
 of the above dimensions, while the slightly larger tubes form 
 clusters of six or more, which appear on the surface as patches 
 or " monticules," which are but faintly or not at all elevated 
 above the general level. Tabulae horizontal, complete, remote, 
 equally distributed through all the tubes of the colony, and 
 often placed at corresponding levels in contiguous tubes, so 
 that the corallum breaks up into a series of concentric strata. 
 
 Obs. The type of this species is a large and massive coral, 
 which occurs in the Trenton Limestone of Canada. With this 
 I formerly associated certain large and lobate Monticuliportz 
 from the Cincinnati group of Ohio and the Hudson River for- 
 mation of Canada, similar in form to some of those included by 
 Hall under the name of Chcztetes lycoperdon, Say (Geol. Mag., 
 Dec. ii. vol. ii. p. 177). I have not yet had the opportunity of 
 examining these latter forms microscopically, but I imagine 
 that I shall find I was in error in associating these with the 
 
322 TABULATE CORALS. 
 
 Trenton Limestone species. On the other hand, a minute 
 examination of the corals of the Hudson River group of 
 Canada, which have commonly been spoken of as " puff-ball 
 varieties of Stenopora fibrosa" and which I used to regard (op. 
 jam cit. p. 176) as a mere variety of M. petropolitana, Pand., 
 has shown me that these are in reality entirely identical in 
 internal structure with the M. undulatd of the Trenton Lime- 
 stone, from which they only differ in their smaller size and 
 hemispherical or spheroidal shape (PI. XIV., fig. 3). I have 
 figured thin sections of both for comparison. 
 
 Tangential sections of both the Trenton Limestone and 
 Hudson River group examples of M. undulata (PI. XIV., fig. 
 4 and fig. 3 a) show the corallites to be strikingly thin-walled, 
 and markedly angular, while, except for the occasional presence 
 of a cluster of somewhat extra-sized tubes, their dimensions are 
 very uniform. Here and there, of course, small corallites will 
 occur, but these are simply young tubes, such as would be seen 
 in any tangential section of a Favosites, and they do not form 
 part of a regular series of special corallites. That this view is 
 correct is shown by their very occasional occurrence, but is still 
 more conclusively proved by vertical sections (PI. XIV., figs. 
 3 b and 4 a). These show that all the corallites those forming 
 the clusters as well as those composing the mass of the colony 
 are precisely similar in their structure, and are not divisible 
 into a series with remote and one with crowded tabulae. All 
 alike have thin, flexuous, often closely undulated walls, and in 
 all alike the tabulae are delicate horizontal plates, situated at 
 distances of from a quarter of a line to nearly a line. In all 
 the specimens I have examined there is, also, an evident 
 periodicity of growth, tabulae being periodically developed at 
 corresponding levels in all the tubes, so that the entire corallum 
 breaks up into concentric layers. 
 
 Formation and Locality. Rare in the Trenton Limestone of 
 Peterboro', Ontario. Common (the " puff-ball variety ") in the 
 Hudson River group of Toronto, Weston, and other localities 
 in Ontario. 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 323 
 
 Monticulipora (Monotrypa) Winter!, Nich. 
 (PI. XIIL, figs. 5; 5 a; PI. XIV., figs. 2, 2 a.) 
 
 Spec. Char. Corallum when young, discoid and concavo- 
 convex ; when adult, hemispherical or subglobular. Young 
 examples may be three or four lines in diameter, and less than 
 two lines in greatest height ; while fully-grown specimens may 
 be more than an inch and a half in diameter, and more than an 
 inch in height. The base is free, or attached to some foreign 
 body at one point, and it is either flat or concave, and is 
 covered by a concentrically-striated epithecal membrane. The 
 corallites radiate from the base and open upon the upper sur- 
 face by thin -walled polygonal calices. The surface shows 
 clusters of slightly extra-sized corallites, which are only occa- 
 sionally elevated to form low " monticules." The corallites 
 are all uniformly thin-walled, strictly angular or prismatic in 
 form, and subequal in size, averaging a quarter of a line in 
 diameter. In internal structure they are all alike, all being 
 provided with delicate, remote, complete, and horizontal 
 tabulae. 
 
 Obs. Examples of this species are of common occurrence in 
 the Devonian Limestone of Gerolstein, and are so entirely 
 similar in form (PI. XIIL, figs. 5, 5 a) to the Lower Silurian 
 M. petropolitana, Pand., that a merely macroscopic examina- 
 tion would almost certainly have led to their being identified 
 with the latter form. A microscopic examination, however, 
 shows that their structure is that of Monotrypa, and not that 
 of Diplotrypa, all the tubes alike being essentially similar in 
 their internal characters. Tangential sections (PI. XIV., fig. 2) 
 show that the tubes are essentially uniform in size, a few 
 slightly larger ones forming scattered clusters, while such in- 
 tercalated small ones as are present are obviously merely young 
 corallites. All the tubes also are bounded by very delicate 
 walls, and are regular, angular, and prismatic. Vertical sec- 
 tions (PI. XIV., fig. 2 a] show a complete identity in structure 
 
3 24 TABULATE CORALS. 
 
 in all the corallites, the tabulae being complete and remote, 
 and sometimes placed at corresponding levels in many of the 
 tubes. 
 
 From M. undulata the present species is distinguished by 
 its concavo-convex or regularly hemispherical form, by the 
 more rapid intercalation of the new tubes, and by the greater 
 abundance of the tabulae, while it never attains the dimensions 
 or assumes the lobate habit of the former. 
 
 I have named the species in honour of Herr Winter of 
 Gerolstein, from whom I received much friendly assistance 
 while collecting in the Eifel. 
 
 Formation and Locality. Not uncommon in the Devonian 
 of Gees, near Gerolstein, Eifel. 
 
 Genus PRASOPORA, Nich. and R. Eth., jun., 1877. 
 (Ann. Nat. Hist, ser. 4, vol. xx. p. 38.) 
 
 Gen. Char. Corallum compound, concavo-convex or hemi- 
 spheric in form, composed of numerous prismatic corallites 
 radiating from a wrinkled basal epitheca. Corallites of two 
 kinds, large and small, 1 regularly and uniformly intermingled 
 throughout the entire colony. No " monticules " or clusters of 
 large tubes. All the corallites thin-walled, and prismatic or 
 angular in shape ; the large tubes furnished with an exterior 
 zone of vesicular tabulae surrounding a vacant central tube, 
 which may be crossed by an occasional tabula. Small corallites 
 arranged in a zone (rarely or never quite complete) round the 
 large tubes, and crossed by numerous close-set, complete, and 
 horizontal tabulae. 
 
 1 In our original description of Prasopora (loc. tit.}, as well as in our " Mono- 
 graph of the Silurian Fossils of Girvan," Fasc. I., p. 44, Mr Etheridge and I em- 
 ployed the term of " coenenchymal tubuli " for the small corallites. We did so, 
 however, simply in conformity with the nomenclature employed by Milne-Edwards 
 and Haime, and we expressed the opinion that the small tubes are " really of the 
 nature of rudimentary corallites, which contained in the living state a series of 
 small and specially modified zooids." 
 
GENERA OF CH^ETETID^E AND MONTICULIPORID^E. 325 
 
 Obs. This singular genus was founded by Mr R. Etheridge, 
 jun., and myself for the reception of a small coral from the 
 Lower Silurian deposits of Girvan, Ayrshire, to which we gave 
 
 Fig. 43. Prasopora Graytz, Nich. and Eth., jun. A, Under side of a small example, showing 
 the epitheca, of the natural size. B, Side view of a larger specimen, of the natural size. 
 C, Tangential section enlarged twenty times. D, Vertical section similarly enlarged : 
 a, One of the large corallites ; b, One of the small corallites. The dark shading in the 
 microscopic sections indicates the presence of the matrix. 
 
 the name of Prasopora Grayce. The characters of the genus 
 and species have been so fully treated of by us (loc. cit. and 
 Monograph of the Sil. Foss. of Girvan, Fasc. I., pp. 44-48), 
 that it is unnecessary for me to do more than briefly allude to 
 the most striking features of the structure of the corallum. 
 
 In general form and size the corallum of Prasopora Grayce 
 (fig. 43, A and B) precisely resembles that of moderately young 
 examples of Monticulipora petropolitana, Pand., with which a 
 merely external examination would almost certainly lead the 
 observer to place it. This, therefore, affords another example 
 of the uselessness of attempting to decide the true structure 
 and position of any Monticuliporoid by an appeal to its form 
 and general aspect. The corallum is conspicuously and very 
 remarkably dimorphic, the large and small corallites being uni- 
 formerly distributed throughout the entire colony, and being 
 singularly different in internal structure. The structure of the 
 large corallites is most easily recognised in longitudinal sections 
 (fig. 43, D, a), in which each is seen to possess a central tube, 
 occupying the axis of the visceral chamber, and entirely sur- 
 
326 TABULATE CORALS. 
 
 rounded by a circumferential zone of peculiarly modified tabulae. 
 The central tube may be open throughout, but it is usually 
 intersected, at remote intervals, by delicate horizontal tabulae. 
 Surrounding the central tube on all sides, and forming its walls, 
 is 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 next tabulae 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 the section does not pass accu- 
 rately through the median plane of the corallites (as it very 
 commonly does not), then it comes to intersect the exterior 
 tabulate zone, and the cut edges of the vesicular tabulae appear 
 as transverse lines and simulate ordinary tabulae ; so that in 
 most sections parts of the tubes exhibit one set of appearances, 
 and parts show the other. When examined in tangential sec- 
 tions (fig. 43, c, a), the large corallites are seen to be hexa- 
 gonal, prismatic, or subpolygonal, and in the centre of each is a 
 rounded or oval opening representing the transverse section of 
 the central tube of the corallite. This opening is surrounded 
 by a variable number of curved lines, which are tangents to 
 the margin of the median aperture, or are concentric with it, or 
 intersect one another. These lines are the cut edges of the 
 vesicular tabulae which form the exterior zone of the corallite ; 
 and when thus exhibited they closely resemble the similar 
 lines produced by the transverse section of the central tube 
 and the infundibuliform tabulae in Syringopora. 
 
 The smaller corallites of the colony are seen in tangential 
 sections (fig. 43, c) to be wedged in among the large tubes, 
 round which they are disposed in a single row. The circle 
 thus formed is, however, rarely or never quite complete, and 
 each of the large tubes usually comes into contact at different 
 points with one, two, three, or even four of its neighbours. 
 The small corallites are angular in shape, mostly oblong or 
 trapezoidal, and are very variable in size, being always very 
 much inferior in size to the larger corallites. Vertical sec- 
 
GENERA OF CH&TETID& AND MONTICULIPORIDJ2, 327 
 
 tions (fig. 43, D, b) show also that their internal structure dif- 
 fers entirely from that of the large tubes, and resembles that 
 of the smaller corallites among the Monticuliporidtz generally, 
 the visceral chamber being simply crossed by crowded, com- 
 plete, and horizontal tabulae. 
 
 As regards its affinities, there cannot be any doubt but that 
 Prasopora is a genuine Monticuliporoid, and that it is most 
 nearly allied to that section of Monticulipora which I have 
 named Diplotrypa, and of which M. petropolitana, Pander, is 
 the type. There is, indeed, a distant approach to the peculiar 
 structure of the large corallites of Prasopora in the large vesi- 
 cular tabulae which are commonly found on one side of the 
 visceral chamber in the corresponding corallites of M. (Diplo- 
 trypa) Whiteavesii, Nich. (see PI. XIV., fig. i). The existence, 
 however, of a complete peripheral zone of vesicular tabulae, 
 enclosing a central tube, is a feature of an entirely unique 
 nature, and fully entitles Prasopora to take rank as a distinct 
 genus. 
 
 The only known species of Prasopora occurs commonly in 
 the " Craighead Limestone " (Lower Silurian) of Craighead, 
 near Girvan, Ayrshire, whence it was collected by Mrs Robert 
 Gray. 
 
 Genus DANIA, Milne-Edwards and Haime, 1849. 
 (Comptes Rend., t. xxix. p. 261.) 
 
 The genus Dania was proposed by Milne- Edwards and 
 Haime for the reception of a single species (D. Huronica) 
 from the Upper Silurian of Drummond Island, Lake Huron ; 
 and they give the following as the characters of the genus (Pol. 
 Foss. des Terr. Pal., p. 275) : 
 
 " Corallum massive, composed of prismatic corallites, which 
 are intimately united by their well-developed walls. Tabulae 
 completely horizontal, and continued across contiguous cor- 
 rallites in such a manner as to give rise to continuous lamellae, 
 
328 TABULATE CORALS. 
 
 which divide the entire mass into a series of superposed strata. 
 Calices subpolygonal. No traces of septa." 
 
 Not having seen the original specimens upon which Milne- 
 Edwards and Haime founded the genus Dania, I am unable to 
 give any final opinion as to the validity or the reverse of the 
 genus. It is clear from their description, and still more from 
 their figures, that Dania Huronica is a Chaetetoid or Monti- 
 culiporoid Coral ; and it is also clear that the single character 
 emphasised by Milne-Edwards and Haime namely, the pres- 
 ence of tabulae placed at corresponding levels in contiguous 
 tubes is not of itself sufficient for generic characterisation. 
 This is amply proved by the fact that a like periodic production 
 of tabulse, giving rise to a similar division of the corallum into 
 superimposed concentric layers, occurs in such different forms 
 as Stenopora crinita, Lonsd., from the Carboniferous, and 
 Monticulipora undulata, Nich., from the Lower Silurian, as 
 well as in the familiar Chcetetes radians, Fischer, of the Car- 
 boniferous. Professor Martin Duncan (Third Rep. on the 
 Brit. Foss. Cor.; Rep. Brit. Ass. 1871, p. 128) is of opinion 
 that Dania, E. and H., is inseparable from Chcetetes, Fischer, 
 and in this view he is very probably correct, though I do not 
 know what positive evidence exists upon the point. 
 
 The only other coral that I am acquainted with as having 
 been referred to the genus Dania is the Thecia multiseptosa, 
 A. Romer (Beitrage III., p. 2, PI. 2, f. i, 1855), from the 
 Lower Devonian of Germany- This form was doubtfully 
 referred by Romer to Thecia, but Giebel assigned it to Dania 
 (Sil. Fauna Unterharz, p. 59, PI. 6, f. 3 and 4, 1858), and this 
 view is also taken by Kayser (Fauna d. Alt. Devon. Ablager. 
 des Harzes, p. 223, 1878). Judging from the figures given by 
 Kayser, the close-set tabulae are certainly placed at correspond- 
 ing levels in contiguous corallites ; but there is nothing definite 
 brought forward except this character to justify its being placed 
 in Dania. It appears to be either a member of the genus Chce- 
 tetes or Favosites. 
 
GENERA OF CH&TET1DM AND MONTICULTPORID^E. 329 
 
 Genus BEAUMONTIA, Milne-Edwards and Haime, 1851. 
 (Pol. Foss. des Terr. Pal., p. 276.) 
 
 The genus Beaumontia was founded by Milne-Edwards and 
 Haime (loc. cit. supra] for the reception of certain Carbonifer- 
 ous and Devonian Corals, to which they ascribed the following 
 common characters : 
 
 " Corallum generally massive ; the corallites usually prismatic 
 and amalgamated by their walls, but occasionally partially free. 
 The walls thin, provided with an epitheca. The tabulae vesi- 
 cular, or, at any rate, irregular, occasionally exhibiting upon 
 their surface septal striae." 
 
 The distinguished French observers just quoted regard 
 Beaumontia as corresponding in the series of the Chcetetidce 
 to Michelinia, De Kon., in the series of the Favositidce ; and 
 they assert that the walls of the corallites are destitute of 
 mural pores. If this last character be certainly established, 
 then the genus may be regarded as undoubtedly distinct ; but 
 the general resemblance of the corallum in the species of Beau- 
 montia to Michelinia would rather lead one to suspect that 
 mural pores may really exist, and that the genus is truly refer- 
 able to the Favositidce. Not, however, having had any oppor- 
 tunity of examining specimens of Beaumontia, I am necessarily 
 unable to pronounce any opinion on this point. I may add, 
 however, that Dr Lindstrom (Ann. Nat. Hist., ser. 4, vol. 
 xviii. p. 1 6) refers Beaumontia to the Favositidce i while Prof. 
 Martin Duncan (Third Rep. on the Brit. Foss. Corals ; Rep. 
 Brit. Ass., 1871, p. 135) regards the genus as being properly 
 referable to the Halysitidcz. I am not aware, however, of any 
 published evidence which would positively decide between 
 these opposing views. 
 
330 
 
 CHAPTER XIV. 
 
 LABECHID^:. 
 
 THE extraordinary Upper Silurian genus Labechia, E. and H., 
 alone constitutes this group, and its characters are so abnormal 
 that we must in the meanwhile regard it as the type of a special 
 family, to which the name of Labechida may be applied. As 
 we have, however, to deal in this family with only a single 
 genus, comprising only a single species, the characters of the 
 group will be sufficiently elucidated by a consideration of the 
 structure of the genus. As a definition of the group it will be 
 sufficient to say that it comprises calcareous corals (?), composed 
 of laminar or submassive expansions, which are fixed by the 
 centre of the base, and have the rest of the lower surface 
 covered with an epitheca ; the skeleton being composed of a 
 series of calcareous, primitively tubular, but finally more or 
 less completely solid columns, which project above the surface 
 as so many rounded or elongated imperforate tubercles ; the 
 spaces between the columns filled with a cellular tissue of len- 
 ticular vesicles, and the intervals between the surface-tubercles 
 covered by a continuous and imperforate calcareous membrane. 
 
 Genus LABECHIA, Edwards and Haime, 1851. 
 (Pol. Foss. des Terr. Pal., p. 279.) 
 
 Gen. Char. Corallum usually having the form of a larger 
 or smaller laminar expansion, which is attached by a portion of 
 its base to some foreign object, the remainder of the lower 
 
LABECHID&. 
 
 33* 
 
 surface being covered by a concentrically - striated epitheca. 
 Upper surface covered with rounded or elongated, sometimes 
 partially confluent, tubercles, which are quite solid, and are 
 separated by an imperforate calcareous membrane. In internal 
 structure, the corallum consists of a great number of cylindrical 
 calcareous columns, which are directed vertically upwards from 
 the basal epitheca, and the upper ends of which constitute the 
 surface-tubercles above mentioned. The columns sometimes 
 appear to be solid throughout ; sometimes they exhibit more or 
 less distinct traces of a minute central tube ; so far as certainly 
 observed, they are apparently solid at their upper ends. The 
 interspaces between the columns are occupied by a series of 
 lenticular vesicles, the convexities of which are directed up- 
 wards, and the uppermost layer of which gives rise to the 
 seemingly imperforate membrane which forms the whole of the 
 upper surface between the tubercles. 
 
 Obs. The genus Labechia was originally founded by Milne- 
 Edwards and Haime for the reception of the singular L. con- 
 
 Fig. 44. Labechia conferta, E. and H. A, A small specimen from the Upper Silurian ol 
 Gotland, of the natural size. B, Portion of the upper surface of the same enlarged, show- 
 ing the surface-tubercles, c, Part of a vertical section of the same, enlarged : <z, the cal- 
 careous columns represented as opaque ; b, the lenticular vesicles, filled with calcite. 
 
 ferta of the Upper Silurian rocks, which is still the only de- 
 scribed species of the genus. As to the structure and affinities 
 of Labechia, the French authors regarded it as referable to the 
 ChcetetintB) and they describe it as having a corallum with con- 
 fluent and not distinct calices, the " visceral chambers filled up 
 
332 TABULATE CORALS. 
 
 with complete, horizontal, closely-set tabulae, and presenting 
 quite rudimentary septa ; " while they regard the surface-tuber- 
 cles as processes springing from the edge of the walls (Brit. 
 Foss. Cor., p. 269). Professor Martin Duncan (Third Rep. on 
 Brit. Foss. Corals; Rep. Brit. Ass., 1871, p. 128) appears to 
 take nearly the same view of the affinities of Labechia as that 
 put forward by Edwards and Haime ; but he considers that it 
 should be regarded as simply a sub-genus of Monticulipora. 
 No evidence, however, in support of this view is actually ad- 
 duced, so that I can merely mention the opinion held by this 
 distinguished authority. On the other hand, Dr Lindstrom 
 (Ann. Nat. Hist, ser. 4, vol. xviii. p. 4) correctly pointed out 
 that there is not in Labechia " the least trace of any wall cir- 
 cumscribing any calicle, or of any septa ; " and he adopts the 
 view which will be more fully noticed at a later period that 
 the genus is not Actinozoan at all, but truly Hydrozoan in its 
 affinities. Lastly, the internal structure of Labechia, as eluci- 
 dated by means of microscopic sections, was, so far as I am 
 aware, first pointed out by Dr Murie and myself in a memoir 
 upon the Stromatoporoids (Journ. Linn. Soc., vol. xiv. p. 232). 
 The skeleton of Labechia is calcareous, and entirely resem- 
 bles that of many of the composite Corals in its general form 
 (fig. 44, A), constituting, as it does, a laminar expansion, attached 
 by a basal peduncle, and having its lower surface covered by 
 a concentrically -striated epitheca. On looking at the upper 
 surface of the colony (fig. 44, B, and PI. XV., fig. 4 a), the 
 most striking feature is the apparent total absence, even in the 
 best-preserved examples, of any of the apertures or " calices " 
 that one would expect to find in any normal compound corallum. 
 On the contrary, the whole of the upper surface is covered 
 by a thin imperforate calcareous membrane, which is studded 
 closely and throughout with blunt, elevated, conical, or elon- 
 gated solid tubercles, which sometimes run into one another 
 and give rise to vermicular ridges. No other features than the 
 above can be recognised by a mere examination of the exterior 
 of the perfect corallum. As regards the internal structure, 
 
LABECHID^E. 333 
 
 thin vertical sections (fig. 44, c) at once show that the surface- 
 tubercles are the summits of a series of vertical columns which 
 spring from the epitheca below, and are separated by intervals, 
 which are in general equal to their own width. As viewed in 
 sections of this kind, the columns appear to be composed of 
 homogeneous granular carbonate of lime, which often shows 
 no differentiation into parts. In many cases, however, a central 
 darker or lighter portion may be distinguished from the mar- 
 gins. In tangential sections (PI. XV., fig. 4), on the other 
 hand, the transversely-divided columns appear as so many oval 
 or rounded bodies, separated by small intervals, and their real 
 structure can now be more satisfactorily studied than in long 
 sections. It was originally believed by Dr Murie and myself 
 that the columns were absolutely and throughout solid and 
 homogeneous, and in many instances they certainly appear 
 to be so, while their upper ends seem to be generally solid. 
 In the examination, however, of a series of thin tangential 
 sections, I find that in many cases the columns really show a 
 distinct differentiation of their tissues. I find, namely, that 
 the columns exhibit in cross-section a more or less distinct 
 composition out of delicate concentric lamellae (PI. XV., fig. 4), 
 the outermost of which are occasionally denser than the others, 
 and form a distinct marginal line ; while there exists centrally 
 a larger or smaller axial area, which may be either darker or 
 lighter than the rest of the column, and may be surrounded by 
 a definite dark marginal ring. This central area appears really 
 to be a central tube, which is sometimes persistent, but in other 
 cases becomes filled up, in process of growth, with dense scler- 
 enchyma-. There is thus reason to believe that the columns 
 of Labechia are primitively tubular, but that the median tube is 
 finally largely or entirely obliterated ; while I have at present 
 no positive evidence which would go to show that the axial 
 canal is ever absolutely continued to the summit of the column, 
 so as to open on the surface by a distinct aperture. As a rule, 
 the surface-tubercles appear to be absolutely solid and imper- 
 forate ; but I have been occasionally able to detect a minute 
 
334 TABULATE CORALS. 
 
 central depression at their apices, which would appear to show 
 that the central tubes of the columns are really sometimes open 
 above. In specimens which have been slightly weathered, 
 also, one may often recognise under the microscope the exist- 
 ence of an unmistakable central tube in the columns, though I 
 certainly cannot affirm that I have ever been able to detect 
 any openings to which the name of " calices" could be applied. 
 
 The interspaces between the columns in the skeleton of 
 Labechia are entirely filled (fig. 44, c) with a cellular tissue 
 formed by curved calcareous lamellae, which have their convex- 
 ities directed upwards, and give rise to a series of lenticular 
 vesicles which extend from the epitheca below to the surface 
 above, and appear to be bounded superiorly and superficially 
 by a delicate calcareous membrane. In tangential sections (PI. 
 XV., fig. 4) the cut edges of the curved lamellae which form 
 the lenticular vesicles appear as irregular curved lines extend- 
 ing between the transversely-divided columns, and subdividing 
 the intervening space into irregular compartments. Both in 
 vertical and in tangential sections, the appearances presented 
 by the interstitial tissue present some curious resemblances to 
 those exhibited by species of Fistulipora (such as F. minor, 
 M'Coy, and F. incrassata, Nich.), in which the tabulae of the 
 small corallites coalesce and give rise to vesicular tissue. 
 
 Having now briefly discussed the intimate structure of La- 
 bechia, it remains to make a few remarks upon its possible affin- 
 ities and systematic position. The most recent and most widely 
 adopted theory upon this subject is that put forward by Dr 
 Lindstrom (Ann. Nat. Hist, ser. 4, vol. xviii. p. 4). Accord- 
 ing to this acute observer, the skeleton of Labechia in its earliest 
 stages of growth consists of "a very thin circular disc, with 
 concentric lines of growth beneath, and having the superior 
 surface studded with blunt spines, which radiate from the cen- 
 tre, and also coalesce and form continuous ridges. In this state 
 it reminds one of nothing more than the sclerobasis of the 
 Hydrozoan genus Hy dr actinia ; and the only difference seems 
 to be that Labechia is entirely calcareous, whilst Hydractinia 
 
LABECHID^E. 335 
 
 is corneous. During the course of growth the primitive disc 
 of Labechia is increased in thickness by the addition of suc- 
 cessive thin strata, which closely conform to the subjacent 
 fundamental crust, being elevated where the spines are situ- 
 ated. As these successive layers leave a small space between 
 them, and are in themselves very thin, they give rise to a false 
 appearance of tabulae." 
 
 Apart from the fact that our present knowledge of the minute 
 structure of Labechia will not allow us to accept the above 
 account of the development of the skeleton as entirely correct, 
 there are certain general considerations which preclude an 
 unhesitating acceptance of the Hydractinian affinities of the 
 genus. The most important of these considerations are, in 
 the first place, that the skeleton of Hydractinia is encrusting, 
 whereas that of Labechia is entirely like that of many corals, 
 and is provided with a basal " epitheca ; " while, secondly, 
 the columns of Labechia are not certainly known to be per- 
 forated at their summits, and there is at present no evidence of 
 the existence of any superficial cells or openings which may be 
 supposed to have given exit to the zooids. 
 
 As we have previously seen, the genus Labechia was referred 
 by Milne-Edwards and Haime to the Chatetina, and has been 
 more recently regarded by Professor Martin Duncan as a 
 sub-genus of Monticulipora. It is, indeed, quite clear that if 
 Labechia be a coral at all, then it will find its nearest ally in 
 the Monticuliporidcz, and especially in Fistulipora, M'Coy. 
 From this point of view, it is worth while to glance for a 
 moment at the resemblances presented by Labechia confer ta, 
 E. and H., and Fistulipora incrassata, Nich., as regards their 
 internal structure. Thus, if we compare the vertical section 
 of these two types (see fig. 44 c, and PI. XV., 3 b] we see 
 that in both the basis or general tissue of the skeleton is made 
 up of a series of lenticular vesicles, traversed at regular inter- 
 vals by the vertical columns in Labechia, and by the tabulate 
 tubes of the large corallites in the Fistulipora. Similarly in 
 tangential sections (PL XV., 4, and PL XV., fig. 3 a), we have 
 
336 TABULATE CORALS. 
 
 the transversely -divided columns of Labechia connected by 
 irregular lines representing the cut edges of the lenticular 
 vesicles ; while in the Fistulipora we have the cut sections of 
 the large tubes united by lines, which are also the cut edges of 
 the lenticular vesicles, but which in this case are regular in form 
 and mark off the boundaries of the small corallites. When we 
 consider the above resemblances, we are very much tempted to 
 conclude that Labechia is a coral similar to Fistulipora (or to 
 Propora in the series of the Helioporidce), but having the vis- 
 ceral chambers of the large corallites largely or totally obliter- 
 ated in process of growth. The conversion of some of the 
 corallites into spines or columns is a phenomenon which we 
 have seen to occur in some of the Monticuliporidce (e.g., in 
 Dekayid), and would not, therefore, be an absolutely unex- 
 ampled occurrence. If, however, we were to accept this view, 
 we should have to believe that in Labechia it is the large coral- 
 lites of the colony which have their cavities obliterated, and thus 
 become columnar, no such thing having been noticed among 
 other types of corals. Moreover, in the case of corals like 
 Fistulipora and Propora, we know exactly what is the nature 
 of the interstitial vesicular tissue. We know, namely, that this 
 tissue is -formed simply by the coalescence and anastomosis 
 of the tabulae of a series of small interstitial corallites, the 
 walls of which are imperfectly developed ; and we know that 
 the calices of these small corallites can often be detected on 
 the surface in the intervals between the large tubes. (In this 
 connection it should be remembered that the mouths of the 
 small corallites of Fistulipora are commonly closed by a cal- 
 careous membrane, so that only the calices of the large tubes 
 can be recognised at the surface). On the other hand, there 
 is no distinct evidence that the vesicular tissue of Labechia 
 is formed in a manner similar to the above, by the conflu- 
 ence of the tabulae of a series of small corallites ; and, upon 
 any view, we are confronted with the inexplicable circum- 
 stance that no apertures or " calices " have ever been cer- 
 tainly detected on the surface of the skeleton. Till open- 
 
LABECHIDJE. 337 
 
 ings of some kind have been detected, or till some sort of 
 explanation can be given as to their absence, it appears 
 impossible to come to any definite conclusion as to the affi- 
 nities and zoological position of Labechia^ since surface-open- 
 ings are as essential to our conception of a coralligenous 
 Hydrozoon as to that of an Actinozoon. At the same time, 
 the resemblances which I have pointed out between Labechia 
 and certain of the Fistuliporce should not be lost sight of, and, 
 pending more complete investigations, I am disposed at pres- 
 ent to consider that we have in these points of likeness the 
 real clue to the true relationships of the former. 
 
 As to its geological range, the only described species of 
 Labechia is the L. conferta, E. and H., of the Upper Silu- 
 rian, which is a familiar fossil in the Wenlock Limestone 
 of Britain and the Continent of Europe. I have never seen 
 any example of the genus in the corresponding formation 
 (Niagara Limestone) in North America ; but I possess a 
 specimen of Labechia from the Cincinnati group of Ohio, 
 thus extending the range of the genus to the Lower Silu- 
 rian ; though I have not yet determined whether or not 
 this ancient form is specifically identical with the L. conferta 
 of Europe. 
 
INDEX. 
 
 The names of genera and species which are actually described in this work are distinguished by 
 means of an asterisk. Names of genera and species that are regarded as synonyms are 
 printed in italics. 
 
 Acropora, Oken, 105. 
 
 * Alveolites, Lam., 117. 
 Alveolites celleporatus, D'Orb., 82. 
 Alveolites cervicornis, De Blainv., 82. 
 Alveolites escharoides, Lam., 126. 
 Alveolites Fischeri, Bill., 91. 
 Alveolites Fischeri, Nich., 91. 
 Alveolites frondosa, Nich., 94. 
 Alveolites Grayi, Edw. and H., 128. 
 
 * Alveolites Labechei, Edw. and H., 128. 
 Alveolites reticulata,'D& Blainv., 82. 
 Alveolites spongites, D'Orb., 82. 
 
 * Alveolites suborbicularis, Lam., 126. 
 *Arasopora, Nich. and Eth., jun., 165. 
 
 Arasopora australis, Nich. and Eth., 
 
 jun., 166, 167. 
 
 Astrcea stylophora, Eaton, 143. 
 Astrocerium, Hall, 37, 40, 54. 
 *Aulopora, 208, 219, 220, 221. 
 Aulopora cornuta, Bill., 117. 
 Aulopora repens, Edw. and H., 220. 
 Aulopora spicata, Goldf., 112. 
 Aulopora umbellifera, Bill., 116. 
 Auloporidas, Nich., 20, 219. 
 Axopora, Edw. and H., 14. 
 
 Battersbyia, Edw. and H., 242. 
 
 * Beaumontia, Edw. and H., 329. 
 
 * Billingsia, De Kon., 185. 
 
 Calamopora, Goldf., 37, 42. 
 Calamopora basaltica, Goldf. (pars), 
 56. 
 
 Calamopora Gothlandica, Goldf., 46. 
 Calamopora polymorpha, Goldf., 84. 
 Calamopora polymorpha, var. ramoso- 
 
 divaricata, Goldf., 82. 
 Calamopora polymorpha, var. gracilis, 
 
 Goldf., 85. 
 Calamopora spongites, var. ramosa, 
 
 Goldf., 82. 
 Calamopora spongites, var. tuberosa, 
 
 Goldf., 126. 
 Calapcecia, Bill., 162. 
 Calapcecia Anticostiensis, Bill., 163. 
 Calapcecia Canadensis, Bill., 163. 
 Calapcecia Huronensis, Bill., 163. 
 Callopora, Hall, 304. 
 Callopora incrassata, Nich., 308. 
 
 * Cannapora, Hall, 204. 
 Ceramopora, supposed relations of to 
 
 Monticulipora, 282, 286. 
 
 * Chastetes, Fischer, 260. 
 Chcetetes attritus, Nich., 298. 
 Chcetetes(f) Bowerbanki, Edw. and H., 
 
 72. 
 
 Chcetetes Dalei, Nich., 296. 
 Chcetetes mammulatus, Edw. and H., 
 
 294. 
 Chcetetes petropolitanus, Nich., 316. 
 
 * Chastetes radians, Fischer, 266. 
 Chcetetes ramosus, Edw. and H., 296. 
 Chatetes ramosus, Nich., 296. 
 Chcetetes undulatus, Nich., 321. 
 
 * Chastetidas, 27, 253. 
 
 * Chonostegites, Edw. and H., 152. 
 
340 
 
 INDEX. 
 
 * Chonostegites Clappi, Edw. and H., 
 
 153, 154, 155- 
 
 Cladochonus, 217, 222, 223. 
 Cladochonus crassus, M'Coy, 222, 223, 
 
 224. 
 Cladochonus Michelini, Edw. and H., 
 
 220, 222, 223. 
 Cladopora, Hall, 79, 80. 
 Cladopora Canadensis, Rom., 94. 
 Cladopora Fischeri, Rom., 91. 
 
 * Ccenites, Eichw., 130. 
 
 * Coenites juniperinus, Eichw., 134. 
 
 * Ccenites linearis, Edw. and H., 135. 
 
 * Columnaria, Goldf., 191. 
 
 * Columnaria alveolata, Goldf., 195. 
 Columnaria alveolata, Hall, 200. 
 Columnaria alveolata, Bill., 200. 
 Columnaria alveolata, Nich., 200. 
 Columnaria alveolata, Rom.. 200. 
 
 * Columnaria calicina, Nich., 197. 
 Columnaria Goldf ussi, Nich., 184. 
 Columnaria Gothlandica, Edw. and 
 
 H, 195. 
 
 * Columnaria (?) Halli, Nich., 200. 
 Columnaria Hertzeri, Rom., 197. 
 Columnaria multiradiata, Castelnau, 
 
 195. 
 
 Columnaria rigida, Bill., 196. 
 Columnaria stellata, Rom., 195. 
 Columnariadas, Nich., 17, 18, 186. 
 
 * Columnopora, Nich., 159. 
 
 * Columnopora cribriformis, Nich., 164. 
 
 * Constellaria, Dana, 292, 300. 
 
 * Constellaria antheloidea, Hall, 301. 
 Cyathophora loivensis, Dale Owen, 97. 
 
 * Dania, Edw. and H., 327. 
 
 * Dekayia, Edw. and H., 291, 297. 
 
 * Dekayia attrita, Nich., 298. 
 Dendropora, Michelin, 102, 103, 105, 
 
 1 06. 
 Dendropora explicita, Michelin, 105, 
 
 1 06. 
 
 Dendropora ornata, Rom., 106. 
 Dendropora elegantula, Rom., 108. 
 
 * Diplotrypa, Nich., 292, 312. 
 
 Emmonsia, Edw. and H., 37, 41, 68. 
 Emmonsia hemispherica, Edw. and 
 H., 67. 
 
 Favistella, Hall, 191. 
 Favistella, Dana, 191. 
 Favistella calicina, Nich., 197. 
 
 Favistella stellata, Hall, 195. 
 
 * Favosites, Lam., 37. 
 Favosites alveolaris, Hall, 67. 
 Favosites basaltica, Goldf., 52, 56, 57, 
 
 62, 63. 
 Favosites Billingsii, Rom., 46, 55. 
 
 * Favosites Bowerbanki, Edw. and H., 
 
 sp., 72. 
 Favosites (Fistulipora) Canadensis, 
 
 Bill., 44. 
 Favosites cervicornis, Edw. and H., 82. 
 
 * Favosites clausa, Rom., 75. 
 Favosites clausa, Lindstr., 112, 113. 
 Favosites cristata, Edw. and H., 87. 
 Favosites cronigera, D'Orb., 82. 
 Favosites dubia, De Blainv., 84. 
 Favosites dubia, Nich., 82. 
 Favosites Emmonsii, Rom., 67, 68. 
 Favosites favosa, Goldf., 46, 53, 54. 
 
 * Favosites Forbesi, Edw. and H., 56. 
 Favosites Forbesi, var. discoiuea, 
 
 Roemer, 58, 152. 
 
 * Favosites Forbesi, var. Eifelensis, 
 
 Nich., 61. 
 
 * Favosites Forbesi, var. tuberosus, 
 
 Rom., 62. 
 
 * Favosites Forbesi, var. Waldronensis, 
 
 Nich., 60. 
 Favosites Goldfussi, Edw. and H., 46, 
 
 52, 54- 
 
 * Favosites Gothlandica, Lam., 46. 
 
 * Favosites hemispherica, Yand. and 
 
 Shum., 67. 
 
 Favosites limitaris, Rom., 82, 85. 
 Favosites Lonsdalei, D'Orb., 87. 
 Favosites Lonsdalei, Lindstr., 87. 
 Favosites Niagarensis, Hall, 46, 55. 
 Favosites petropolitanus, Pand., 313. 
 Favosites placenta, Rom., 44. 
 Favosites polymorpha, Bill., 82. 
 Favosites polymorpha, Lonsd., 87. 
 Favosites polymorpha, Goldf., 84. 
 Favosites reticulata, Edw. and H., 82, 
 
 83, 85. 
 
 Favosites reticulata, Nich., 82. 
 Favosites spongites, Lonsd., 72, 128. 
 Favosites spongites, Phill., 126. 
 Favosites Troosti, Edw. and H., 51. 
 Favosites tuberosus, Rom., 57, 62. 
 Favosites turbinata, Bill., 38, 39, 68, 
 
 69. 
 
 Favosites Winchelli, Rom., 46, 55. 
 Favositidae, 16, 17, 30-36. 
 Favositipora, Sav. Kent, 34, 35, 36, 45. 
 
INDEX. 
 
 34' 
 
 * Fistulipora, M'Coy, 292, 304. 
 
 * Fistulipora minor, M'Coy, 306. 
 
 * Fistulipora incrassata, Nich., 308. 
 
 * Fistulipora proporoides, Nich., 310. 
 
 * Fletcheria, 203, 206. 
 Fletcheria clausa, Lindstrom, 113. 
 
 Haimeophyllum, Bill., 152. 
 Haimeophyllum ordinatum, Bill., 153, 
 
 154, 155- 
 
 "-" Halysites, Fischer, 226. 
 Halysites agglomerata, Hall, 228, 229. 
 Halysites catenularia, Linn., 228, 229. 
 Halysites escharoides, Lam., 227, 228, 
 
 229, 230. 
 
 Halysitidae, 21, 22, 226. 
 Harmodites, Fischer, 207, 211. 
 
 * Heliolites, Dana, 243. 
 Heliolites favosus, Salt., 190. 
 Heliopora, De Blainv., 7, 25, 26. 
 Helioporidae, 25, 241. 
 Heteropora, 256. 
 
 * Heterotrypa, Nich., 291, 293. 
 Houghtonia, Rom., 159, 161. 
 Houghtonia Huronica, Rom., 164, 165. 
 Hydrocorallinas, 8, 13, 14. 
 
 Koninckia, Edw.and H., 9, 34, 35, 36, 45. 
 
 * Labechia, Ecl\v. and H., 330. 
 
 * Labechia conferta, Edw. and H., 331. 
 
 * Labechidas, 29, 330. 
 
 * Laceripora, Eichw., 180. 
 Laceripora cribrosa, Eichw., 181. 
 Limaria Steininger, 130. 
 Limaria clathrata, Lonsd., 134. 
 Limaria ramulosa, Hall, 134. 
 
 * Lyellia, Edw. and H., 249. 
 
 * Lyopora, Nich. and Eth.,jun., 187. 
 
 * Lyopora favosa, M'Coy, sp., 190. 
 
 Madreporites cr is tat us, Blum., 87. 
 
 * Michelinia, De Kon., 139. 
 Michelinia Clappi, Rom., 155. 
 Michelinia cylindrica, Edw. and H., 
 
 IS4. 157- 
 Michelinia intcrmittens, Bill"., 153, 154, 
 
 155- 
 
 Michelinia trochiscus, Rom., 143. 
 Millepora, Lam., 2, 3, 5, 6, 7, 8, 9, n, 
 
 13. H. 
 Milleporidas, 12-14. 
 
 * Monilopora, Nich. and Eth., jun., 223. 
 Monilopora crassa, M 'Coy, sp., 223, 224. 
 
 * Monotrypa, Nich., 293, 320. 
 
 * Monticulipora, D'Orb., 269. 
 
 * Monticulipora (Heterotrypa) mammu- 
 
 lata, D'Orb., 294. 
 
 * Monticulipora (Diplotrypa) petropoli- 
 
 tana, Pand., 313. 
 
 * Monticulipora (Heterotrypa) ramosa. 
 
 D'Orb., 296. 
 
 * Monticulipora (Monotrypa) undulata, 
 
 Nich., 321. 
 
 * Monticulipora (Diplotrypa) White- 
 
 avesii, Nich., 316. 
 
 * Monticulipora (Monotrypa) Winteri, 
 
 Nich., 323. 
 Monticuliporidae, 28, 255, 269. 
 
 Nebulipora, M'Coy, 269. 
 
 * Nodulipora, Lindstr., 186. 
 *Nyctopora, Nich., 182. 
 *Nyctopora Billingsi, Nich., 184. 
 
 Orbipora, Eichw., 269. 
 Orbitulites, Eichw., 269. 
 
 * Pachypora, Lindstr., 77. 
 
 * Pachypora cervicornis, De Blainv., sp., 
 
 82. 
 
 * Pachypora cristata, Blum., sp., 87. 
 
 * Pachypora Fischeri, Bill., sp., 91. 
 
 * Pachypora frondosa, Nich., 94. 
 
 * Pachypora lamellicornis, Lindstr., 80, 
 
 Si. 
 Pal&opora (?) favosa, M'Coy, 190. 
 
 * Pinacopora, Nich. and Eth., jun., 250. 
 
 * Plasmopora, Edw. and H., 245. 
 
 * Pleurodictyum, Goldf., 142. 
 Pleurodictyum Americanum, Roemer, 
 
 I43> 144- 
 
 Pleurodictyum problematicum, Goldf., 
 142, 144, 145, 146. 
 
 * Pleurodictyum stylophorum, Eaton, 
 
 sp., 143- 
 
 Pocillopora, Lam., 2, 3, 4, 9, 14, 15, 16. 
 Pocilloporidae, 14-16. 
 Porosphaera, Steinm., 14. 
 
 * Prasopora, Nich. and Eth., jun., 324. 
 Prasopora Grayae, Nich. and Eth., jun., 
 
 325- 
 
 * Propora, Edw. and H., 247. 
 Pyrgia, Edw. and H., 219, 222. 
 Pyrgia Michelini, Edw. and H., 222. 
 
 Quenstedtia, Rom., 114. 
 Quenstedtia umbellifera, Rom., 116. 
 
342 
 
 INDEX. 
 
 Rhabdopora, Echv. and H., 102, 105, 106. 
 
 * Roemeria, Edw. and H., 177. 
 Roemeria infundibulifera, Goldf., 177. 
 
 * Romingeria, Nich., 114. 
 
 * Romingeria umbellifera, Bill., sp., 116. 
 
 Seriatopora, Lam., 15, 16, 104, 105. 
 
 Seriatoporidae, 16. 
 
 Stellipora, Hall, 300. 
 
 Stellipora antheloidea, Hall, 301. 
 
 * Stenopora, Lonsd., 168. 
 Stenopora, M'Coy, 269. 
 
 Stenopora Jackii, Nich. and Eth.Jun., 
 
 173- 
 
 Stenopora ovata, Lonsd., 172, 174. 
 Stenopora Tasmaniensis, Lonsd., 281. 
 
 * Striatopora, Hall, 97. 
 
 * Striatopora Linneana, Bill., 100. 
 
 * Syringolites, Hinde, 178. 
 Syringolites Huronensis, Hinde, 179. 
 
 * Syringopora, Goldf., 207. 
 
 * Syringopora geniculata, Phill., 217. 
 "* Syringopora reticulata, Goldf., 215. 
 
 Syringoporidae, 18, 19, 203. 
 
 Tabular, nature of, 9, 11. . 
 
 Tabulata, characters of, i ; history of, 
 
 2-9 ; groups of, 12-29. 
 Tetradiidse, 23, 231. 
 
 * Tetradium, Dana, 231. 
 Tetradium minus, Saff., 232, 233. 
 
 * Thecia, Edw. and H., 236. 
 *Thecia Swindernana, Goldf., 235, 237. 
 
 Thecidae, 24, 235, 236. 
 Thecostegites, Edw. and H., 203, 205. 
 
 * Trachypora, Edw. and H., 102. 
 
 * Trachypora Davidsoni, Edw. and H., 
 
 102, 103, 104, no. 
 
 * Trachypora elegantula, Bill., 108. 
 
 * Trachypora ornata, Rom., 106, 108. 
 Tubuliclidia, Lonsd., 168. 
 
 *Verrhipora, Hall, m. 
 
 * Vermipora clausa, Lindstr., sp., 113. 
 
 Zoantharia Tabulata (see Tabulata). 
 Zoantharia Tubulosa, 20, 219. 
 
 THE END. 
 
 PRINTED BY WILLIAM BLAOKWOOD AND SONS. 
 
'Jo 
 
 'to 
 
 ; >'(} li/o! 
 ft ,.frk,vi 
 
PLATE I. 
 
 Fig. i. Transverse section of a typical example of Favosites Gothlandica, Lam., 
 from the Wenlock Limestone of Gotland, showing the regular, polygonal, 
 thin-walled corallites, enlarged five times. 
 
 Fig. i a. A vertical section of the same, similarly enlarged. A mural pore is 
 seen here and there. 
 
 Fig. 2. Transverse section of a specimen of Favosites Gothlandica, v&r.favosa, 
 Gold., from the Hamilton Group (Devonian) of Erie Co., New York, en- 
 larged five times. Some of the corallites show the marginal foldings of 
 the tabulae as so many dark spaces. 
 
 Fig. 3. Upper and under surfaces of an exceedingly young specimen of Favo- 
 sites Gothlandica, Lam., from the Wenlock Limestone of Dudley, of the 
 natural size. 
 
 Fig. 4. Outline of part of the upper surface of the corallum of a specimen of 
 F. Gothlandica, var. favosa, Gold., from the Niagara Limestone of Mani- 
 toulin Island, of the natural size; and a single corallite enlarged four 
 times to show the marginal depressions or plications of the tabulae. 
 
 Fig. 5. A few corallites of a specimen of F. Gothlandica, from the Niagara 
 Group of Manitoulin Island, with well - developed septal spines (Astro- 
 cerium of Hall), of the natural size, and one corallite enlarged four times. 
 
 Fig. 6. Transverse section of Favosites Gothlandica, var. Billingsii, Rom., from 
 the Hamilton Group of Arkona, Ontario, enlarged five times. 
 
 Fig. 7. Transverse section of an adult example of Favosites Forbesi, E. and H., 
 from the Wenlock Limestone of Stoke-Edith. enlarged five times. 
 
H.Alleyne Nicholson del. 
 
 Plate. 1. 
 
 C.P.erjefLulith. 
 
 Mintern Bros imp. 
 
PLATE II. 
 
 Fig. T. A young and nearly globular specimen of Favosites Forbesi, E. and H., 
 
 from the Wenlock Limestone of Dudley, of the natural size. 
 Fig. i a. Upper portion of the vertical section of a similar specimen of the 
 
 same species, from the Wenlock Limestone of Benthall Edge, enlarged 
 
 five times. 
 Fig. i b. Transverse section of another young example of the same species, 
 
 from the Wenlock Limestone of Dudley, enlarged five times. 
 Fig. 2. A young specimen of Favosites Forbesi, E. and H., var. Waldronensis, 
 
 Nich., from the Niagara Group of Waldron, Indiana, of the natural size. 
 Fig. 2 a. Part of a tangential section of another young example of the same, 
 
 from the same locality, enlarged five times. 
 
 Fig. 2 b. Vertical section of the same species, enlarged five times. 
 Fig. 3. Transverse section of Favosites Forbesi, E. and H., var. Eifelensis, 
 
 Nich., enlarged five times, showing the well-developed septa. 
 
H.Alleyne Nicholson del. 
 
 Plate. 11. 
 
 C. Berieau lith. 
 
 MinternBros imp.' 
 
PLATE III. 
 
 Fig. i. An example of Favosites Forbesi, E. and H., var. Eifelensis, Nich., from 
 
 the Devonian of Gerolstein in the Eifel, of the natural size. 
 Fig. i a. Portion of the surface of the same, enlarged twice. 
 Fig. i b. Vertical section of the same, enlarged five times, showing the septal 
 
 spines, seen laterally and in cross-section, as well as the tabulae. 
 Fig. 2. A very young example of Favosites Forbesi, E. and H., var. tuberosa, 
 
 Rom., from the Corniferous Limestone of Port Colborne, Ontario, of the 
 
 natural size. The calices in the lower part of the corallum are closed by 
 
 an epitheca 1 ! or opercular growth. 
 Fig. 2 a. Portion of the surface of a large and fully-grown example of the same, 
 
 from the same locality, of the natural size. The lower calices have 
 
 undergone closure by the epitheca. 
 Fig. 2 b. Portion of the surface of a large specimen of the same, from the 
 
 Hamilton formation of Arkona, Ontario, of the natural size. 
 Fig. 2 c. Transverse section of a specimen of the same, from the Hamilton 
 
 formation of Arkona, Ontario, enlarged five times. 
 Fig. 2 d. Part of a vertical section of the same specimen as the last, enlarged 
 
 five times. Besides the tabulae proper, the section shows some of the 
 
 peculiar transverse squamae, or incomplete tabulae, characteristic of this 
 
 peculiar form. 
 Fig. 2 e. Portion of two corallites of a silicified example of the same, from the 
 
 Corniferous Limestone of Port Colborne, Ontario, enlarged three times. 
 
 The interior of the tubes exhibits the peculiar transverse squamae above 
 
 alluded to, and the mural pores are also seen. 
 Fig. 3. Transverse section of Favosiles (Emmonsia) hemisphcerica, Yand. and 
 
 Shumard., enlarged five times, from the Corniferous Limestone of Port 
 
 Colborne, Ontario. 
 Fig. 3 a. Portion of one of the tubes of the same specimen, similarly enlarged, 
 
 showing the close-set biserial mural pores. 
 Fig. 3 b. Portion of a vertical section of the same specimen, in which the 
 
 tubes are quite empty, enlarged five times, showing the incomplete and 
 
 flexuous tabulae. 
 Fig. 4. Portion of a transverse section of Favosites Bowerbanki, E. and H., 
 
 from the Wenlock Limestone of Benthall Edge, enlarged five times. 
 
 Several of the corallites show an incomplete division of their tubes by 
 
 means of laminae directed inwards. 
 
 Fig. 4 a. Transverse section of a single corallite of the same specimen, show- 
 ing incompleted fission, enlarged ten times. 
 Fig. 4 b. Part of a vertical section of the same species, from the Wenlock 
 
 Limestone of Gotland, enlarged five times, showing the tabulae and mural 
 
 pores. 
 
H. Alleyne. Nicholson, del. 
 
 Plate. III. 
 
 C.Berjeau.lith. 
 
 Mntern Bros 
 
 amp. 
 
PLATE IV. 
 
 Fig. i. Portion of the corallum of Favosites clansus, Rom., from the Hamilton 
 
 formation (Devonian) of Arkona, Ontario, of the natural size. In the upper 
 
 portion of the specimen the calices are open. 
 Fig. i a. A few of the calices of the same, closed with an operculum, enlarged 
 
 five times. 
 
 Fig. i b. Tangential section of the same, enlarged five times. 
 Fig. i c. Vertical section of the same, enlarged five times. 
 Fig. 2. Pachypora lamellicornis, Lindst, from the Upper Silurian of Gotland, of 
 
 the natural size. 
 Fig. 2 a. Portion of a tangential section of the same, showing the dense 
 
 secondary deposit of sclerenchyma in the interior of the tubes, enlarged 
 
 seven times, with a single corallite enlarged still further, to show the 
 
 rudimentary septa. 
 Fig. 2 b. Portion of a longitudinal section of the same, similarly enlarged, 
 
 showing the thick walls, remote tabulae, and mural pores. 
 Fig. 2 c. Portion of the surface of the same, enlarged five times. 
 Fig. 3. Portion of the corallum of Pachypora (Favosites) cervicornis, De Blainv., 
 
 from the Devonian of Gerolstein in the Eifel, of the natural size. The 
 
 calices are omitted over the greater portion of the surface. 
 Fig. 3 a. Portion of the surface of the same, enlarged about six times. 
 Fig. 3 b. Portion of a tangential section of a specimen of the same, in which 
 
 the cavities of the fossil are filled with oxide of iron, enlarged seven times. 
 
 The thickening of the walls of the corallites is shown, as well as the lateral 
 
 communication of the visceral chambers of some of the corallites. 
 Fig. 3 c. Portion of a transverse section of the same, taken in the axis of a 
 
 branch, similarly enlarged, showing how greatly the tubes are narrowed by 
 
 secondary deposits of sclerenchyma, the original walls still remaining 
 
 quite distinct. 
 Fig. 3 d. Portion of a longitudinal section of the same, enlarged seven times, 
 
 showing the great and irregular thickening of the corallites near their 
 
 mouths, together with remote tabulae, and large- sized mural pores. The 
 
 specimen is partially infiltrated with oxide of iron. 
 Fig. 4. Small and imperfect specimen of Pachypora (Favosites} cristata, E. and 
 
 H., from the Wenlock Limestone of Dormington, near Stoke-Edith, of the 
 
 natural size. 
 
 Fig. 4 a. Portion of the surface of the same, enlarged five times. 
 Fig. 4 b. Portion of the surface of a specimen of Pachypora (Favosites) cristala, 
 
 var. major, E. and H., from the same locality, similarly enlarged. 
 
H.Alleyne. Nicholson del. 
 
 Plate. IV. 
 
 C . Berjeau. lith . 
 
 Mntern Bros imp. 
 
PLATE V. 
 
 Fig. i. Transverse section of Pachypora (Favosites) cristata, E. and H., enlarged 
 
 seven times, showing the thickening of the tubes by a secondary deposit 
 
 of sclerenchyma. From the Wenlock Limestone of Dormington, near 
 
 Stoke-Edith. 
 Fig. i a. Vertical section of the same, showing the thickened walls, tabulae, 
 
 and mural pores, enlarged seven times. 
 Fig. i b. Vertical section of another specimen of the same, from Benthall 
 
 Edge, showing the tabulae, together with numerous septal spines ; enlarged 
 
 seven times. 
 
 Fig. 2. Fragment of Striatopora Linneana, Billings, from the Hamilton forma- 
 tion of Ontario, of the natural size. 
 
 Fig. 2 a. A small portion of the surface of the same, enlarged five times. 
 Fig. 2 b. Transverse section of a branch of the same, enlarged seven times. 
 Fig. 2 c. Portion of a tangential section of the same, enlarged seven times, 
 
 showing the thickened walls, and spine-like septa. 
 Fig. 2 d. Part of a vertical section of the same, enlarged seven times, showing 
 
 the thickened walls, the occasional tabulae, and the mural pores. 
 Fig. 3. Fragment of Trachypora ornata, Rom., from the Hamilton formation 
 
 of Erie County, New York, of the natural size. 
 Fig. 3 a. Small portion of the surface of the same, enlarged five times, showing 
 
 the ornamentation. 
 Fig. 3 b. Vertical section of the same, enlarged seven times, showing the 
 
 thickened walls, the occasional tabulae, the numerous spiniform septa, and 
 
 the few mural pores. 
 Fig. 3 c. Tangential section of the same, enlarged seven times, showing the 
 
 thickening of the walls by concentric lamellae of sclerenchyma and the 
 
 rudimentary septa. 
 Fig. 4. Fragment of Trachypora elegantula, Bill., from the Hamilton Group of 
 
 Arkona, Ontario, of the natural size. 
 Fig. 4 a. Small portion of the surface of the same, enlarged five times, showing 
 
 the peculiar ornamentation. 
 
 Fig. 4 b. Transverse section of a branch of the same, enlarged five times. 
 Fig. 4 c. Vertical section of a branch of the same, enlarged seven times, show- 
 ing the immense thickening of the corallites by the deposition in their 
 
 interior of successive laminae of sclerenchyma. 
 
H.Alleyne Nicholson del. 
 
 Plate. V. 
 
 r: 
 
 C.Berjeau.lith. 
 
 MinternBros imp. 
 
"io 
 
PLATE VI. 
 
 Fig. T. A colony of Vermipora clausa, Lindst, from the Upper Silurian of 
 Gotland, enlarged twice. 
 
 Fig. i a. Transverse section of the same, enlarged seven times, showing spini- 
 form septa. 
 
 Fig. i b. Vertical section of the same, enlarged seven times, showing tabula? 
 and mural pores. 
 
 Fig. 2. Portion of the surface of the corallum of Alveolites suborbicularis, Lam., 
 from the Eifel, enlarged seven times, showing no apparent traces of the 
 single septal ridge. 
 
 Fig. 2 a. Portion of a tangential section of the same, also from the Eifel, show- 
 ing the form of the corallites. A few of the tubes show a single septal 
 tooth. Enlarged twelve times. 
 
 Fig. 2 b. Vertical section of the same, enlarged twelve times, showing tabulae. 
 The section cuts the tubes at right angles to their long diameters. 
 
 Fig. 3. Tangential section of Alveolites Labechei, E. and H., from the Upper 
 Silurian of Benthall Edge, enlarged twelve times, showing the compressed 
 tubes and well-developed spiniform septa. 
 
 Fig. 3 a. Vertical section of the same, enlarged twelve times, showing the 
 spiniform septa, and the tabulag. The section cuts the corallites parallel 
 with their short diameters. 
 
 Fig. 4. Portion of a tangential section of Alveolites Goldfusst, Bill., from the 
 Hamilton Group (Devonian) of Canada, enlarged twelve times, showing 
 the thin-walled compressed tubes, and the absence of septal spines or 
 ridges. 
 
 Fig. 5. A fragment of Cxnites juniperimis, Eichw., of the natural size, and en- 
 larged five times. From the Wenlock Limestone of Stoke-Edith. 
 
 Fig. 5 a. Part of a vertical section of the same, enlarged twelve times, show- 
 ing the thickening of the tubes close to the mouths, the tabulae, and the 
 mural pores. 
 
 Fig. 5 b. Portion of a transverse section of a branch of the same, enlarged 
 twelve times, showing the compressed corallites in the axis of the stem, 
 with unthickened walls. 
 
H.Alleyne Nicholson del. 
 
 Plate VI. 
 
 C . Berieau lith . 
 
 Mntern Bros imp . 
 
PLATE VII. 
 
 Fig. i. Fragment of a laminar specimen of Cxnites linearis, E. and H., of the 
 natural size, from the Wenlock Limestone of Benthall Edge. 
 
 Figs, i a and i b. Different forms of the calices of the same, enlarged eight 
 times. 
 
 Fig. i c. Tangential section of the same, enlarged twelve times. 
 
 Fig. i d. Portion of a section of the same, taken at right angles to the flat 
 surfaces of the expansion, enlarged twelve times, showing the great thick- 
 ening of the tubes as they bend outwards to the surface. 
 
 Fig. i e. Portion of a longitudinal section of the same, taken through the 
 median plane of the corallum, enlarged twelve times, showing tabulae and 
 mural pores. 
 
 Fig. 2. A small specimen of Columnopora cribriformis, Nich., from the Cincin- 
 nati Group of Ohio, of the natural size, viewed from above. 
 
 Fig. 2 a. Portion of a tangential section of a specimen of the same, from the 
 Cincinnati Group of Ohio, enlarged five times, showing the rudimentary 
 septa, the mural pores, and the "intramural canals." The visceral cavities 
 are rilled with the matrix. 
 
 Fig. 2 b. Cross-section of a single corallite of the same, enlarged ten times, 
 showing the " intramural canals." 
 
 Fig. 2 c. Part of a vertical section of another specimen of the same, from the 
 Cincinnati Group (Hudson River Group) of the Credit River, Ontario, en- 
 larged five times. In parts the section cuts through the centre of the 
 tubes, and shows the inosculating tabulae ; but in other parts it more or 
 less nearly coincides with the plane of the walls of the corallites, and shows 
 the large and numerous mural pores. 
 
 Fig. 2 d. Part of the preceding section, enlarged ten times, showing the cribri- 
 form wall. 
 
 Fig. 3. Fragment of Laceripora cribrosa, Eichw., of the natural size. (After 
 Eichwald. ) 
 
 Fig. 3 a. Surface of the same, enlarged. (After Eichwald.) 
 
 Fig. 3 b. Longitudinal section of the tubes of the same, enlarged. (After 
 Eichwald.) 
 
H.Alleyne Nichols on del. 
 
 Plate VII. 
 
 C.Berjeau lith. 
 
 Mintern Bros imp. 
 
PLATE VIII. 
 
 Fig. i. Section of the corallum of Plcurodictyum stylophornm, Eaton., taken 
 parallel with and just above the flat base, enlarged two and a half times, 
 showing the tabulae, pores, and rudimentary septa. The sections of the 
 "vermiform body" are left white, for clearness' sake. From the Hamilton 
 Group (Devonian) of the State of New York. 
 
 Fig. i a. Part of a tangential section of the same, similarly enlarged. A few 
 mural pores are seen in section ; and the sections of the " vermiform 
 body" are, as before, left white, except in one place where some dark 
 ovoid bodies occur within its cavity. 
 
 Fig. i b. Vertical section of a specimen of the same, similarly enlarged, show- 
 ing the inosculating tabula? and mural pores. The visceral chambers of 
 all the corallites, except one, are filled with the matrix, and the sections of 
 the " vermiform body " are, as before, left unshaded. 
 
 Fig. 2. Portion of the corallum of Chonostcgites Clappi, E. and H. ( = Haimeo- 
 phyllum ordinatum, Bill.), of the natural size, viewed laterally. Corniferous 
 Limestone (Devonian), Walpole, Ontario. 
 
 Fig. 2 a. Portion of the upper surface of a broken corallum of the same, of 
 the natural size, showing the convex tabulae, and the upper surfaces of the 
 lateral connecting-floors. 
 
 Fig. 2 b. Part of a transverse section of the same, enlarged twice. The actual 
 corallites are cut across transversely, but the lateral connecting-floors are 
 only seen where their undulations happen to bring them into the plane of 
 the section. 
 
 Fig. 2 c. Part of a vertical section of the same, enlarged twice, showing the 
 form and mode of increase of the corallites, their hollow and vesicular 
 lateral connecting -floors, and the inosculating and subvesicular tabulae, 
 the upper surfaces of which are serrated with spiniform projections. Both 
 this and the preceding drawing (fig. 2 b} are taken from sections of a 
 specimen in which the tubes are exceptionally wide apart. 
 
 Fig. 3. Small specimen of Lyopora favosa, M'Coy, sp., from the Lower Silurian 
 of Craighead, Girvan, of the natural size. (After Nicholson and R. Et he- 
 ridge, jun.) 
 
 Fig. 3 a. A few calices of the same enlarged. 
 
H.Alleyne Nicholson dd. 
 
 Plate V1IL 
 
 C . Berjeau lith. 
 
 Mintern Bros imp. 
 
mworfa 
 
 
PLATE IX. 
 
 Fig. i. Part of a vertical section of Stenopora ovata t Lonsd., from the Carbon- 
 iferous rocks of Queensland, enlarged about twenty-five times, showing the 
 periodical annular thickenings of the corallites, the remote tabulae, placed 
 at corresponding levels in contiguous tubes, and the mural pores. 
 
 Fig. i a. Part of a tangential section of the same specimen, taken just below 
 the surface, and similarly enlarged, showing the hexagonal form of the 
 tubes and the peculiar appearances which they present when the section 
 cuts them across their unthickened or thickened portions. 
 
 Fig. 2. Part of a tangential section of Lyopora favosa, M'Coy, sp., from the 
 Lower Silurian of Craighead, Girvan, enlarged eight times, showing the 
 rudimentary septa, and the thickened walls, in which a few small vacuities 
 are visible. 
 
 Fig. 2 a. Part of a vertical section of another specimen of the same, similarly 
 enlarged, showing the thick walls and the remote complete tabulae. As 
 in the preceding section, a few minute irregular vacuities are seen here 
 and there in- the substance of the wall. 
 
 Fig. 3. A specimen of Nyctopora JSillingsii, Nich., from the Trenton Limestone 
 of Canada, of the natural size ; viewed from above. 
 
 Fig. 3 a. Part of a transverse section of the same, enlarged eight times, show- 
 ing the complete fusion of the walls of the corallites, and the marginal 
 septa, together with an occasional mural pore. 
 
 Fig. 3 b. Part of a vertical section of the same, enlarged eight times, showing 
 the tabulae and mural pores. Where the section cuts through the centre of 
 the tubes, the tabulae are alone seen; where the section passes nearly along 
 the plane of the wall of a tube, the marginal septa and mural pores are 
 brought into view. 
 
 Fig. 3 c. Small part of the surface of the same, enlarged ten times, showing the 
 calices. 
 
 Fig. 4. A small specimen of Billingsia alvcolaris, De Koninck, from the De- 
 vonian of New South Wales, of the natural size (after De Koninck). The 
 corallum is split, and shows the large mural pores connecting contiguous 
 tubes. 
 
 / 
 
H.Alleyne Nicholson, del 
 
 Plate 
 
 3c 
 
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PLATE X. 
 
 Fig. i. Part of a transverse section of Columnaria alveolata, Goldf. ( - Favistella 
 stellata, Hall), enlarged five times, showing the characters of the septa. 
 From the Cincinnati Group of Ohio. 
 
 Fig. i a. Longitudinal section of a single tube of the same, similarly enlarged. 
 Owing to the curvature of the tube, the cut edges of the septa appear in 
 parts of the section. 
 
 Fig. 2. Part of a transverse section of Columnaria calicina, Nich., from the 
 Hudson River Group of Canada, enlarged five times, showing the structure 
 of the wall and the characters of the septa. 
 
 Fig. 2 a. A single tube of the same, in longitudinal section, similarly enlarged, 
 showing tabulae, and part of the cut edges of the septa. 
 
 Fig. 3. Part of a transverse section of Columnaria (?) Haiti, Nich. ( - Colum- 
 naria alveolata, of Hall, Billings, &c.), enlarged five times, showing the 
 amalgamation of the walls of the corallites and the marginal septa. 
 
 Fig. 3 a. Part of a vertical section of the same, similarly enlarged, showing the 
 tabulae. In part of the section the cut edges of the septa are seen. 
 
 Fig. 4. Part of a vertical section of Syringopora geniculata, Phill., enlarged five 
 times. From the Carboniferous Limestone of Shap, Westmorland. 
 
 Fig. 4 a. Part of a transverse section of the same specimen, enlarged five times, 
 showing the thickened tubes. 
 
 Fig. 4 b. Transverse section of a corallite of the same, enlarged about twenty- 
 five times, showing the contraction of the visceral chamber by a secondary 
 deposit of sclerenchyma within the true wall. 
 
 Fig. 5. Transverse section of a single corallite of Syringopora reticulata, Goldf., 
 from the Carboniferous Limestone of Kendal, Westmorland, enlarged about 
 fifteen times, showing the spiniform septa, and the cut edges of the tabulae. 
 
 Fig. 6. Transverse section of a few of the tubes of Halysites cscharoides, Lam., 
 from the Upper Silurian of Gotland, enlarged ten times, showing the spini- 
 form septa, and the apparent absence of any small zooids. 
 
 Fig. 7. Transverse section of a few of the tubes of Halysites catemilaria, Linn., 
 from the Wenlock Limestone of Dudley, enlarged five times, showing the 
 presence of small zooids and the absence of septa. 
 
 Fig. 7 a. Vertical section of another specimen of the same, enlarged five times, 
 showing the tabulae of the larger and smaller zooids. 
 
K. Alley ne Nicholson, del. 
 
 Plate X. 
 
 bo. 
 
 Water st on, Sons t Stewart.Iith 15 Edin 1 
 
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PLATE XI. 
 
 Fig. i. Transverse section of a few of the tubes of Haly sites catenularia, Linn., 
 from the Wenlock Limestone of Dormington, Stoke-Edith, enlarged ten 
 times, showing the absence of septa in the large tubes, and the structure 
 of the intermediate tubes. The epitheca is left unshaded. 
 
 Fig. i a. Part of a vertical section of another specimen of the same, from the 
 same locality, enlarged five times. The specimen is one in which the 
 tubes are of unusually large size, and the tabulae of the intermediate tubes 
 are subvesicular. 
 
 Fig. 2. Portion of the surface of Thecia Swindernana, Goldf., enlarged about 
 ten times. Wenlock Limestone, Dormington Quarry, Stoke Edith. 
 
 Fig. 2 a. Part of a transverse section of the same, enlarged ten times, showing 
 the obtuse septal ridges, the communication of the cavities of the polypes 
 by horizontal channels, and the filled-up tubuli of the interstitial tissue. 
 
 Fig. 2 b. A small part of the same transverse section, enlarged twenty times, 
 showing the filled-up interstitial tubuli. 
 
 Fig. 2 c. Part of a vertical section of the same, enlarged ten times, showing the 
 tabulate larger corallites, the horizontal canals uniting the visceral cham- 
 bers of these, and the small tubules of the interstitial tissue. 
 
 Fig. 2 d. Small portion of the same section, enlarged twenty times, showing the 
 interstitial tubuli. 
 
 Fig. 3. Part of a transverse section of Propora tubtdata, E. and H., enlarged 
 five times, from the Wenlock Limestone of Dudley. The specimen is one 
 in which the septa are unusually small and short. 
 
 Fig. 3 a. Part of the same section, enlarged ten times. 
 
 Fig. 3 b. Part of a vertical section of the same specimen, enlarged ten times. 
 
 Fig. 4. Portion of the surface of an altered specimen of Lyellia glabra, E. and 
 H., from the Upper Silurian of Iowa, of the natural size (copied from 
 Edwards and Haime). 
 
 Fig. 4 a. Portion of a specimen of Lyellia glabra, E. and H., seen from one 
 side, enlarged (copied from Edwards and Haime). 
 
 Fig. 5. Part of a tangential section of Plasmopora petaliformis, E. and H., from 
 the Wenlock Limestone of Gotland, enlarged five times. 
 
H. Alley ne Nicliolson, del. 
 
 Plate XI. 
 
 C.Berjeau,litt. 
 
 Wateiston.Sons k. Stewart, Lrth IS ESm r 
 
PLATE XII. 
 
 Fig. i. Part of a vertical section of a young specimen of Plasmopora petaliformis, 
 E. and H., from the Wenlock Limestone of Dudley, enlarged five times, 
 showing the faintly-marked walls of the smaller corallites, and their convex 
 tabulae. 
 
 Pig"." ^ Portion of a tangential section of Hdiolites megastoma, M'Coy, from the 
 Wehlpck Limestone of Dudley, enlarged five times. 
 
 Fig. 2 a. Part of a vertical section of the same specimen, enlarged five times, 
 showing the comparatively well-marked walls of the smaller corallites and 
 their strong horizontal tabulae. 
 
 Fig. 3. Under surface of a small specimen of Pinacopora Grayi, Nich. and 
 Eth. jun., from the Lower Silurian of Girvan, Ayrshire, of the natural size, 
 showing the concave base, with its concentrically-striated epitheca. 
 
 Fig. 3 a. Upper surface of another specimen of the same, from which all the 
 short corallites except a few on one margin have been denuded, leaving the 
 superior aspect of the epithecal plate to view, of the natural size. 
 
 Fig. 3 b. Portion of the corallum of the same, as naturally split along a hori- 
 zontal plane, showing the large and small corallites, with their visceral 
 chambers filled with dark matrix, enlarged five times. 
 
 Fig. 3 c. Part of a vertical section of the corallum of the same, embedded in 
 an opaque matrix, enlarged five times. 
 
 Fig. 3 d. Tangential section of another specimen of the same, infiltrated with 
 calcite, showing the large and small corallites (/, p and /, t), enlarged 
 twenty times. 
 
 Fig. 3 e. Vertical section of another example of the same, enlarged twenty 
 times, showing the large corallites (/, /), and the smaller and more closely 
 tabulate tubes (/, /). [Figs. 3-3 e are copied from the " Monograph of the 
 Silurian Fossils of Girvan," by R. Etheridge, jun., and the author.] 
 
 Fig. 4. Tangential section of a specimen of Chcetdes radians, Fischer, from the 
 Carboniferous Limestone of Russia, showing the thick and completely 
 confluent walls of the corallites, with an occasional inward projection in- 
 dicative of commencing fission, enlarged ten times. 
 
 Fig. 4 a. Vertical section of the same, enlarged ten times, showing the remote 
 and regularly placed tabulae. 
 
 Fig. 4 b. Portion of surface of the same, enlarged ten times, showing the form 
 of the calices. 
 
 Fig. 4 c. Portion of a tangential section of a specimen of the same, from the 
 Carboniferous Limestone of Shap, Westmorland, enlarged ten times. 
 
 Fig. 4 d. A small portion of the same section as the last, enlarged twenty 
 times, showing the complete amalgamation of the walls of the tubes, and 
 the presence in some of the tubes of the inward projections produced in 
 the process of fission of the old corallites. 
 
H.Alleyne Nicholson, del. 
 
 Plate All. 
 
 C. Berjeau, litt. 
 
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PLATE XIII. 
 
 Fig. i. Part of a tangential section of Monticulipora (Heterotrypa} mammulata, 
 D'Qrb., from the Cincinnati Group of Cincinnati, Ohio, enlarged twenty 
 times, showing the two sets of corallites. 
 
 Fig. i a. Small portion of the preceding section, enlarged fifty times, showing 
 the structure of the walls, and the occasional presence of spines (modified 
 corallites). 
 
 Fig. i b. Part of a vertical section of the same species, enlarged twenty times, 
 showing the different disposition of the tabulae in the two sets of corallites 
 respectively. 
 
 Fig. 2. Part of a tangential section of Monticulipora (Heterotrypa) ramosa, F. 
 and H., from the Cincinnati Group of Cincinnati, Ohio, enlarged twenty 
 times, showing' the two sets of corallites. 
 
 Fig. 2 a. Part of a vertical section of the same species, enlarged twenty times, 
 showing the different disposition of the tabulae in the two sets of tubes. 
 
 Fig. 3. Under surface of a specimen of Monticulipora (Diplotrypa) petropolitana, 
 Pand., from the Lower Silurian rocks of Sweden, of the natural size, show- 
 ing the epithecal plate. 
 
 Fig. 3 a. The same specimen, viewed in profile, of the natural size. 
 
 Fig. 3 b. Part of a tangential section of the same, enlarged twenty times, show- 
 ing the uniformly thin walls of the corallites, and the small angular tubes 
 wedged in at the angles of junction of the larger ones. 
 
 Fig. 3 c. Part of a vertical section of the same, showing the two sets of tubes, 
 and the increase in the number of the tabula? as the exterior is approached, 
 enlarged twenty times. 
 
 Fig. 4. Under surface of Monticulipora (Diplotrypa) Whiteavesii, Nich., of the 
 natural size, showing the concave base and epithecal plate. From the 
 Trenton Limestone of Peterboro', Ontario. 
 
 Fig. 4 a. The same specimen viewed in profile. 
 
 Fig. 4 b. Part of a tangential section of the same, enlarged twenty times, show- 
 ing the different groups of corallites. 
 
 Fig. 5. Side view of a specimen of Monticulipora (Monotrypa) Winteri, Nich., 
 of the natural size, from the Devonian Limestone of Gerolstein in the 
 Eifel. 
 
 Fig. 5 a. Under surface of the same, of the natural size, showing the epithecal 
 plate partially removed by weathering. 
 
Plate XIII. 
 
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PLATE XIV. 
 
 Fig. i. Portion of a vertical section of Monticulipora (Diplotrypa) Whiteavesii, 
 Nich., from the Trenton Limestone of Peterboro', Ontario, enlarged twenty 
 times, showing the closely-tabulate small corallites, and the twofold con- 
 stitution of the tabulae of the large corallites. 
 
 Fig. 2. Part of a tangential section of Monticulipora (Monotrypa} Winteri, 
 Nich., from the Devonian Limestone of Gerolstein in the Eifel, enlarged 
 twenty times, showing the thin-walled polygonal corallites, with an occa- 
 sional young tube intercalated. 
 Fig. 2 a. Part of a vertical section of the same, showing the thin walls, and the 
 
 uniform development of the tabulae of all the corallites. 
 
 Fig. 3. A medium -sized specimen of Monticulipora (Monotrypa} undulata, 
 Nich., from the Hudson River Group of Toronto, Ontario, of the natural 
 size. The specimen is broken on one side. 
 
 Fig. 3 a. Part of a tangential section of the same, enlarged twenty times, show- 
 ing the thin-walled, and nearly equal- sized corallites. 
 
 Fig. 3 b. Part of a vertical section of the same, enlarged twenty times, show- 
 ing the thin and undulated walls, and the uniform development of the 
 remote tabulae. 
 
 Fig. 4. Part of a tangential section of Monticulipora (Monotrypa) undulata, 
 Nich., from the Trenton Limestone of Peterboro', Ontario, enlarged 
 twenty times. 
 
 Fig. 4 a. Part of a vertical section of the same, enlarged twenty times, showing 
 the thin undulated walls, and the remote tabulae placed at corresponding 
 levels. 
 Fig. 5. One of the star-like elevations of the surface of Constellaria anthdoidea, 
 
 Hall, from the Cincinnati Group of Ohio, enlarged. 
 
 Fig. 5 a. Part of a tangential section of the same, taken just below the surface, 
 enlarged twenty times. The upper part of the portion figured traverses 
 one of the stellate areas or " maculae," while the lower part cuts across a 
 portion of the general surface. 
 
 Fig. 5 b. Part of a vertical section of the same, showing the two sets of coral- 
 lites, enlarged twenty times. 
 
 Fig. 6. Part of a tangential section of a typical example of Monticulipora pul- 
 chella, E. and H., from the Wenlock Limestone of Dudley, enlarged 
 twenty times. The section cuts across one of the clusters of large 
 corallites. 
 
 Fig. 6 a. Small portion of a longitudinal section of the same specimen, show- 
 ing the characters of the corallites just before they open on the surface, 
 enlarged twenty times. 
 
H.AlleyTie Nicholson, del. 
 
 Plate XIV. 
 
 C. Berjeau, lifh 
 
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PLATE XV. 
 
 Fig. i. Fragment of Dekayia attrita, Nich., from the Cincinnati Group of Ohio, 
 of the natural size. 
 
 Fig. i a. Portion of the surface of the same, enlarged. 
 
 Fig. i b. Tangential section of the same, enlarged twenty times, showing the 
 spiniform corallites scattered among the ordinary tubes. 
 
 Fig. i c. Vertical section of the same, enlarged twenty times, showing the 
 characters of the two sets of corallites just before they open on the 
 surface. 
 
 Fig. 2. A small specimen of Fistulipora (Callopora) proporoides, Nich., from 
 the Hamilton Group of Cariandaigua, State of New York, of the natural 
 size. 
 
 Fig. 2 a. Part of the surface of the same, enlarged. The large circular tubes 
 have projecting and open calices, but the mouths of the interstitial angular 
 tubes are mostly closed by a calcareous membrane, and the lines of divi- 
 sion between them are only faintly indicated. 
 
 Fig. 3. Part of the surface of Fistulipora (Callopora) incrassata, Nich., from the 
 Hamilton Group of Arkona, Ontario, enlarged. The mouths of the in- 
 terstitial corallites are seen in the specimen figured ; but they are often 
 concealed from view by a calcareous membrane. 
 
 Fig. 3 a. Part of a tangential section of the same, enlarged twenty times, 
 showing the oval corallites with a slight constriction on one side, sur- 
 rounded by a series of angular corallites. 
 
 Fig. 3 b. Part of a vertical section of the same, enlarged twenty times, showing 
 the remotely-tabulate oval tubes, and the vesicular tabulae of the angular 
 corallites. 
 
 Fig. 4. Part of a tangential section of Labechia conferta, E. and H., from the 
 Wenlock Limestone of Benthall Edge, enlarged ten times, showing the 
 primitively tubular condition of the pillars, and the transversely-divided 
 edges of some of the vesicular tabulae. 
 
 Fig. 4 a. Part of the upper surface of another specimen of the same, from the 
 same locality, enlarged. The surface-tubercles in the specimen figured 
 are more extensively confluent than is usually the case. 
 
A.H.Nicholson, del. 
 
 Plate XV. 
 
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