There are large numbers of fossil Madreporaria known. The existing fauna appears to be but sparingly represented in Palaeozoic times during which flourished a series of extinct and peculiar forms (infra). Some of the existing groups were, however, formerly more numerously represented than at present, e. g. Turbinolidae in the Chalk and Eocene.
1The Astraea of Kowalewsky appears to be the same coral as Astroides.
2There is considerable uncertainty as to the time, mode, etc. of appearance of the tentacles and mesenteries. O. and R. Hertwig have revised (J. Z. xiii. p. 539) de Lacaze Duthiers' conclusions with reference to Actinians, as stated in the text. For a summary of observations, see Balfour, Comp. Embryology, i. pp. 139-143.
The sub-class Zoantharia is divisible into the Actiniaria, Antipatharia, and Madreporaria, the characters of which, as well as of the tribes of Actiniaria, have been already given.
The classification of the Madreporaria presents great difficulties. The anatomy of their soft parts has been little investigated, and the characters of the skeleton alone are not sufficient basis for any sound classification. Moreover, these characters are not trustworthy in all respects j see p. 739. A principal division into Perforata with a skeleton or coenenchyma, perforated throughout by cavities which lodge, so far as is known, coenosarcal tubes, and Aporosa in which the corallum is not so perforated, has been universally recognized. The most recent re-arrangement of the sub-groups of these two main divisions is by Martin Duncan, J. L. S. xviii. 1885.
The Palaeozoic Corals are for the most part classified as Rugosa s. Tetracora/la, but the assemblage is probably artificial. The corallum is simple or colonial, but there is no coenenchyma; it is free or fixed. The septa are arranged in four systems, which are either disposed in a bilaterally symmetrical manner and for the most part feathering from a primary chief septum and two lateral septa, or else are regularly radiate. One or all of the four primary septa (if such are distinguishable) are marked out by size and strength, or by a slight development, in which case they lie in a septal furrow. The septa usually alternate, a large one of the first order and a short incomplete one of the second order. The calycle is usually provided with tabulae and vesicular endotheca, i. e. secondary calcareous deposit. Reproduction was sexual, or asexual, by calycular, or by parietal gemmation. The most interesting forms are the Operculate corals, with one or four moveable opercula marked internally by septa: the horn-shaped Cyathaxonia, simple with well-marked radial septa and median columella, to which the living Duncania is perhaps allied: Stauria, which forms Astraea-like masses with four principal septa in the calycle arranged like a cross, from which the remaining septa tend to radiate, multiplying by septal gemmation (p. 741): Zaphrentis and Menophyllum, simple forms with a deep furrow or fossula lodging the principal septum, and the other septa radiating towards it: Cystiphyllum with a series of calycles one above the other, filled with layers of vesicular endotheca, the vesicles arranged radiately to the axis of the corallum.
See general literature, p. 732.
Actiniaria, see pp. 244-5. Add the following: Cereanthus, O. and R. Hert-wig, Die Actinien, J. Z. xiii. p. 565; apertures in tentacles of, von Koch, M. J. vi.
1880, p. 355. Edwardsia, O. and R. Hertwig, op. cit. p. 582. Zoanthidae, Erd-mann, J. Z. xix. 1886.
Antipatharia. Gephyra, von Koch, M. J. iv. 1887, p. 78 of Appendix dedicated to von Siebold; Gerardia, de Lacaze Duthiers, A. Sc. N. (5), ii. 1864; Antipathes (chiefly A. sub-pennatd), Id. ibid. iv. 1865; A. /arix, von Koch, op. cit.
Madreporaria. Deep-sea forms (with lit.), Moseley, Challenger Reports, ii.
1881. Stylophora, von Koch, J. Z. xi. 1877. Cladocora, von Heider, S.B. Akad. Wien, lxxxiv. Abth. 1, 1881. Flabellum and Rhodopsammia, Fowler, Q. J. M. xxv. 1885; Madrepora, Id. ibid, xxvii. 1887. Stephanotrochus, W. L. Sclater, P. Z. S. 1886, pt. 1. Fungia, G. C. Bourne, Q. J. M. xxvii. 1887. Seriatopora and Pocillopora, Moseley, Q. J. M. xxii. 1882. Reef-building Corals, Quelch, Challenger Reports, xvi. 1886. Classification, Martin Duncan, J. L. S. xviii. 1885 (for technical terms, see pp. 200-2); also Quelch, op. cit. p. 38.
Skeleton, Fowler, supra; von Koch, M. J. v. 1879; development in Astroides, von Koch, Mitth. Zool. Stat. Naples, iii. 1882; increase in number of septa, and on the theca, Id. M. J. viii. 1882; relation of soft parts to skeleton, Id. M. J. xii. 1886.
Asexual reproduction, Semper, Generationswechsel, etc, Z. W. Z. xxii. 1872; on Fungia, see also Moseley, Notes by a Naturalist on the Challenger, 1879, p. 524; cf. general papers, supra, and re?narks in Dana, Coral Islands, pp. 28-38; in Palaeozoic Corals, etc, von Koch, Palaeontographica, xxix. 1882-83
Coral Reefs, Geikie, Nature, xxix. 1883-84 (summary of recent views with lit.)) Guppy, On the recent Calcareous Formations of the Solomon Group, Trans. Roy. Soc. Edinburgh, xxxii. pt. 3, Session 1884-85. Coral Reefs, Darwin (ed. 2), 1874; Corals and Coral Islands, Dana (ed. 2), 1875.
Fossil Corals, Zittel, Palaeontologie, Abth. 1, i. 1876-80; cf. Moseley on Heliopora, Hickson on Tubipora, Nicholson on Corallium, cited note p. 731; Operculate Corals (by Lindstrom), Moseley, Nature, xxviii. 1883.