1. Millepora alcicornis, Forsk., 2. The animal of Millepora nodosa. (After Moseley), 3. Pocillopora aspera, var. lata, Verrill. (After Dana), 4. Favosites favosa, Goldf.; and F. Gothlandica, Lam., 5. Syringopora retiformis, Bill. (After Billings), 8. Aulopora tubaformis, Goldf.; and Cladochonus (Pyrgia) Michelini, Edw. and H. (After Goldfuss, and Edwards and Haime), 9. Halysites catenularia, Linn.; and H. agglomerata, Hall. (Original), 10. Tetradium minus, Safford. (Original), 11. Heliolites megastoma, M'Coy. (Original), . 12. Labechia conferta, Edw. and H. (Original), 13. Alveopora spongiosa, Dana. (After Dana), 14. Forms of Favosites Gothlandica, Lam. (Original), 15. Favosites hemispherica, Yand. and Shum. (After Billings), 16. Pachypora Fischeri, Bill. (Original), 20. Calices of Alveolites suborbicularis, Lam. (After Goldfuss), 21. Michelinia convexa, D'Orb. (After Billings), 22. Pleurodictyum problematicum, Goldf. (After Roemer, and Edwards and Haime); and P. stylophorum, Eaton. (Original), . 23. Diagrams of Sections of Favosites and Pleurodictyum. (Original), . PAGE 30. Sections of Syringopora reticulata, Goldf. (Original), 211 31. Cladochonus Michelini, Edw. and H.; and species of Aulopora. (Original), 220 32. Monilopora crassa, M'Coy, sp. (Original), 224 33. Tetradium minus, Safford. (Original), 233 34. Heteropora Neozelanica, Busk (Original); and H. subreticulata. (After Reuss), . 35. Sections of Monticulipora and Chatetes. (Original), 36. Monticulipora moniliformis, Nich. (Original), 37. Section of Monticulipora moniliformis, Nich. (Original), . 41. Sections of Fistulipora proporoides, Nich. (Original), 42. Monticulipora (Diplotrypa) Whiteavesii, Nich. (Original), 257 274 279 279 . PLATE S. I. Favosites Gothlandica, Lam.; and F. Forbesi, Edw. and H. IV. Forbesi, Edw. and H.; and its varieties. Forbesi, Edw. and H.; F. hemispherica, Yand. and Shum.; and F. Bowerbanki, Edw. and H. clausus, Rom.; and species of Pachypora. V. Species of Pachypora, Striatopora, and Trachypora. Vermipora, Alveolites, and Cœnites. Canites, Columnopora, and Laceripora. Pleurodictyum, Chonostegites, and Lyopora. Halysites, Thecia, Propora, Lyellia, and Plasmopora. Monticulipora (Heterotrypa, Diplotrypa, and Monotrypa). PALEOZOIC TABULATE CORALS. CHAPTER I. THE CLASSIFICATION AND AFFINITIES OF THE "TABULATE CORALS." THE "Tabulata," 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, Introduction, 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 welldeveloped "walls," by the separation of the visceral cavities of the corallites into distinct chambers by transverse partitions or "tabulæ," 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 Astraida by not being dependent on the septa, and forming as many complete horizontal divisions extending from side to side of the general, A 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 : Fam. I. MILLEPORIDÆ.-Corallum principally composed of a very abundant cœnenchyma, distinct from the walls of the corallites, and of a tubular or cellular structure. Septa not numerous; tabulæ numerous and well formed. Genera-Millepora, Lam.; Heliopora, De Blainv.; Heliolites, Dana; Fistulipora, M'Coy; Plasmopora, Edw. and H.; Fropora, Edw. and H.; Axopora, Edw. and H.; Lobopora, Edw. and H. Fam. II. FAVOSITIDE.-Corallum essentially formed by lamellar walls, with little or no cœnenchyma. Visceral chambers divided by numerous and well-developed complete tabulæ. Tribe 1. Favositina.-Corallum massive. Walls perforated. Septa rudimentary. No coenenchyma. Genera-Favosites, Lam.; Michelinia, De Kon.; Koninckia, Edw. and H.; Alveolites, Lam. Tribe 2. Chatetina.-Corallum massive. Walls not perforated. Neither septa nor cœnenchyma. Genera-Chatetes, Fischer; Dania, Edw. and H; Stenopora, Lonsd.; and Constellaria, Dana. Tribe 3. Halysitinæ.-Corallum composed of corallites constituting vertical laminæ 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 Syringopora, Goldf.), and Thecostegites, Edw. and H. Tribe 4. Pocilloporinæ.—Corallum massive, gibbous, or subdendroid, with thick imperforated walls, forming towards the surface an abundant compact cœnenchyma. Septa quite rudimentary. GenusPocillopora, Lam. Fam. III. SERIATOPORIDE.—Corallum arborescent or bushy, with an abundant compact cœnenchyma. Visceral chambers filling up by the growth of the columella and the walls, and showing but few traces of tabulæ. Genera-Seriatopora, Lam.; Dendropora, Michelin; Rhabdopora, Edw. and H. Fam. IV. THECIDE.-Corallum massive, with an abundant, compact, spurious cœnenchyma, produced by the septa becoming cemented together laterally. Tabulæ numerous. Genus-Thecia, Edw. and H. Various additions, modifications, and improvements in the above classification of the "Tabulata" were made by Milne 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 Stylophyllinæ, to include the curious Cretaceous genus Stylophyllum, Reuss, was inserted in the family of the Favositide. 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). 66 The first serious attack upon the classification of Milne-Edwards and Haime, and upon the position of the “ Tabulata," was made by Professor Louis Agassiz, who in 1857 examined the living animal of Millepora, 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 subsequently referred to; but Professor Agassiz based upon his discovery a further conclusion which certainly was not warranted 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 Oculinida (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. cit.), powerfully supported the view that the Favositida are not only true Actinozoa, but that they are really referable to the Zoantharia. In the year 1872 the same high authority published an important memoir upon "The Affinities of the Pala |