SUBCLASS II 



HEXACORALLA 



101 



Cryptocoenia E. and H. Jurassic and Cretaceous. 

 Massive colonies, with corallites united by costae. 

 centre : colnmella absent. Visceral Chamber 



Astrocoenia deeaphylla B. and H. Upper Cretaceous ; Gosau 

 Valley, Austria. «, Corallum, natural size ; b, Caiices enlarged. 



Placocoenia d'Orb. 



Cyathopliora Mich 

 Septa short, not reaching the 

 partitioned off by horizontal 

 tabulae. Jurassic . and Cre- 

 taceous. 



Coccophyllnm Reuss. Massive 

 colonies, with corallites united 

 directly by their walls. Caiices 

 polygonal, septa numerous. Col- 

 umella absent ; visceral Cham- 

 ber tabulated. Alpine Trias. 



Pinacophyllum Frech. Tri- 

 assic. 



Holocystis Lonsd. Massive colonies, with corallites united by costae. Four 

 of the septa larger or stouter than the rest. Tabulae in visceral Chamber. 

 Cretaceous. 



Astrocoenia E. and H. (Fig. 155). Massive colonies. Corallites polygonal, 

 united by their walls ; septa numerous, long. Columella styliform ; only 

 dissepiments present in visceral Chamber. Trias to Tertiary. 



Stephanocoenia E. and H. Like the preceding, but with columella 

 surrounded by cycle of pali. Trias to Recent. 



Phyllocoenia E. and H. {Confusastrea d'Orb. ; Adelastrea Reuss). Massive 

 colonies. Corallites round or oval, imperfectly united by costae. Septa 

 strongly developed, thickened in the middle between theca and the centre. 

 Columella rudimentary. Trias to Tertiary. 



Convexastrea d'Orb. Trias to Cre- 

 ^Tliaa^ taceous. Columnastrea, Stylocoenia E. 



and H., etc. Cretaceous and Tertiary. 



y. Coralla multiplying by fission. 



Haplosmilia d'Orb. Bushy colonies. 

 Corallites usually with dichotomously 

 dividing crests. Caiices circular or 

 elongated ; columella styliform ; theca 

 with ridge-like costae. Jurassic. 



Plocophyllia Reuss (Fig. 156). 



Branching, foliaceous, or massive 



colonies. Corallites either becoming 



free or grouped into detached rows. 



Columella absent. Tertiary. 



Barysmilia E. and H. Corallum massive, forming a thick stem, the apex 



of which is covered with short buds. Caiices oval, sometimes disposed in 



series ; columella rudimentary. Cretaceous. 



Stenosmilia From. Like the preceding, but with lamellar columella. 

 Cretaceous. 



Pachygyra E. and H. Corallites arranged in winding rows, and united by 

 a broad mass of costal coenenchyma. Columella lamellar. Jurassic and 

 Cretaceous. 



Fig. 156. 



Plocophyllia calyculata Reuss. Oligocene ; Monte 

 Carlotta, near Vicenza. Natural size. 



