98 COELENTERATA ANTHOZOA SUB-BRANCH n 



Arabia and the AVest Indies ; while outside the Alps in Europe and in America 

 their distribution is mostly sporadic. In the Miocene and Pliocene the true 

 coral-reefs retreat more and more towards the equator (Red Sea, Java, Japan), 

 while the Hexacwalla which persist in formations of the temperate zone 

 (Vienna Basin, Italy, Touraine) constitute but an insignificant feature of the 

 general fauna. 



Appendix to the Hexacoralla. 



Sub-Order C. TABULATA. 1 Milne-Edwards and Haime. 



Invariably composite corolla composed of tuUform or prismatic corallites. Walls 

 thick, independently calcified, compact, or perforated by connecting mural pores. Septa 

 but slightly developed (usually six or twelve), sometimes represented merely by vertical 

 ridges or rows of spines, and sometimes entirely absent. Visceral chamber partitioned 

 off into successive storeys by tabulae. Synapticulae and dissepiments wanting. 



To the Tabulata were originally assigned by Milne-Edwards and Haime all 

 corals having numerous tabulae and rudimentary septa. Later researches have 

 shown, however, that some of these forms (e.g. Pocilloporidae) belong to the 

 Aporosa, others (Heliopoiidae) to the Octocoralla, and still others (Millepora) to 

 the Hydrozoa ; while the affinities of a few (Chaetitidae, Monticuliporidae) are of 

 such doubtful nature as to be referred by some authors to the Corals, and by 

 others to the Bryozoans. The majority of the typical Tabulata (Favositidae, 

 Syringoporidae, Halysitidae) exhibit close relationships to the Hexacoralla; but 

 since they are for the most part now extinct and are largely confined to the 

 Palaeozoic rocks, the positive determination of their systematic position seems 

 almost hopeless. The ontogeny of the corallites in the Tabulata shows that the 

 development of mural pores is homologous with the process of gemmation. 

 Reproduction sometimes takes place by fission, but generally by means of buds 

 from the edges of the calices at various stages during the growth of the parent 

 corallites. Buds are given oft' early in Aulepora, producing basal corallites only ; 

 periodically in Romingeria, producing verticils of corallites ; periodically and on 

 one side in Halysites, producing linear series of adjacent corallites ; and very 

 frequently in Favosites, etc., producing compact coralla with numerous mural 

 pores representing aborted buds. 



Family 1. Favositidae. Milne-Edwards and Haime. 



Massive w branching coralla. Corallites uniformly piismatic, tall, and united by 

 their walls, which are perforated by large -sized pores. Septa very short, usually 

 represented by but faintly projecting ridges or rows of spines, but seldom completely 

 absent. Tabulae numerous, situated at regular intervals, complete and horizontal, 

 more rarely oblique or irregularly vesicular ("cystoid"). 



The Favositidae are distinguished from the Poritidae, with which Verrill 

 associates them, by their thick, solid walls, which are punctured by round, 



1 Lindstrom, G., Affinities of the Anthozoa Tabulata (Ann. Mag. Nat. Hist. Ser. 4, XVIII.), 1876. 

 /ti/ftuwski, W., Die Chaetitiden der ostbaltischen Silurformation (Verb, der k. russ. min. Gesi-llscli. 

 St. Petersburg), 1877. Nicholson, H. A., On the Structure and Affinities of the Tabulate Corals of 1 lit- 

 Palaeozoic Period. London, 1879. On the Structure and Affinities of the genus Monticulipora. 

 London, 1881. Roemer, F., Lethaea Palaeozoica, I., 1883, p. 416. Waagen, IF., and Wentzd, 11'.. 

 The Salt Range Fossils. Palaeontol. Indica, 1887. Naug, E., Ueber sogeuannte Chaetetes ;ms 

 mesozoischen Ablagerungen (Neues Jahrb. fur Mineral.), 1883, I., p. 171. Beecher, C. E., The 

 Development of a Palaeozoic Poriferous Coral. Symmetrical Cell Development in the Favositidae. 

 (Trans. Conn. Acad. vol. VIII.), 1891. 



