suBCLAss III TABULATA— FAVOSITIDAE 113 



hut slighüy developed (usualli/ six or twelve), sometimes 7'epresented merely hy vertical 

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

 ojf into successive storys by tabulae. Synapiiculae 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 (Focilloporidae) belong to the 

 Aporosa, others (Ilelioporidae) to the Alcyonaria, and still others (MiUepora) to 

 the Hydrozoa. 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 Paleozoic rocks, 

 the determination of their systematic position is a matter of much difficulty. 

 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 ofF early in Aulopora, 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 or branching coralla. Corallites uniformly prismatic, toll 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 regulär 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 perforated by round, 

 sometimes tubiform mural pores. The corallites are usually polygonal in 

 contour, and their walls exhibit in transverse sections a dark, or sometimes 

 light-coloured median line, with thickenings of stereoplasma on either side 

 (Fig. 176, C). The family is exclusively Paleozoic, and plays an important 

 part in the formation of Silurian, Devonian and Carboniferous coralline 

 limestones. 



Favosites Lam. {Calamopora Goldf.) (Fig. 176). Corallum massive, more 

 rarely branching. Corallites prismatic, polygonal, generally hexagonal. 

 Mural pores distributed at considerable intervals. Septa very faintly 

 developed, represented by longitudinal ridges or rows of spines, or occasion- 

 ally obsolete. Tabulae numerous. Ordovician to Carboniferous ; very 

 abundant in Silurian and Devonian. 



W., and Wentzel, J., The Salt Range Fossils. Palaeontol. Indica, 18S7.—Beecker, C. U., The 

 Development of a Palaeozoic Poriferous Coral. — Symiiietrical Cell Development in the Favositidae. 

 Trans. Conn. Acad., 1891, vol. viii. — Wentzel, J., Zur K(3untniss der Zoantharia tabulata. 

 Denkschr. Akad. "Wien, 1895, vol. \xü.—Sardeso7i, F. W., Über die Beziehungen der fossilen 

 Tabulaten zu den Alcyonarien. Neues Jahrb. Mineral., 1896, Supplem. vol. x. — Weissermel, W., 

 Sind die Tabulaten Vorläufer der Alcyonarien? Zeitschr. deutsch, geol. Ges., 1898, vol. 1. — 

 Vinassa de Regny, P. E., Trias-Tabulaten, etc. Res. d. wisseusch. Erforsch, des Balaton-Sees, 

 vol. i. pt. 1, Badapesth, 1901. 



VOL. I I 



