FAMILIES AIS^D GENERA OE THE MADREPORARTA. 



101 



are free only for a small space. Wall naked, and covered with 

 granular costse. The trunk grows by the superposition of layers 

 derived from the costse of the corallites. Columella none. Septa 

 slightly exsert, and regularly dentate. 



Distribution. — Fossil. Jurassic and Cretaceous : Europe. 



This genus corresponds to Barysmilia, but has dentate 

 septa. 



G-enus Spinellia, d'Achiardi, " Gorall. foss. delV alpi Veneti,^^ 

 Mem. della Soc. Italia di sci. nat. torn. iv. no. 1, pt. 2, p. 16 

 (Milan, 1868). 



Colony in the form of a pedunculate lamina, attached, upper 

 surface slightly convex. Corallites in long or short series, some- 

 times flexuous, not united by their walls above. Columella 

 absent. Calicular centres distinct. Epitheca well developed. 

 Intercorallite coenenchyma developed and uniting the corallites. 



Distribution. — Fossil. Eocene : Europe. 



G-enus Phtllastr^a {non Dana), F. de Fromentel, Pal. Fran(^., 

 Terr. cret. p. 488 (1879). 



Colony tall, in the form of dendroid tufts. Corallites united 

 together by a well-developed exotheca. Calicos oval, often 

 deformed by fissiparity. Columella lamellar and short. Septa 

 large, in six cycles, and continued beyond the calicos as short 

 costse, which lose themselves in a granular coenenchyma, which 

 fills the intercalicinal spaces. 

 , Distribution. — Fossil. Cretaceous : Europe. 



G-enus D'Achiardia, Duncan, Fossil Corals and Alcyonaria of 

 Bind, Pal. Ind. ser. xiv. p. 92 (1880). 



Colony large, massive, cylindrical or lobate. Corallites sepa- 

 rated by a dense coenenchyma, which is granulate or semilamellar 

 at the surface. Calicos separate, circular or deformed, rising 

 slightly above the coenenchyma, shallow. Columella flat, variable 

 in development, papillary or not. Septa alternately large and 

 small, barely exsert, dentated. Pali small and before the large 

 septa. Costse rudimentary on the calicos, not found over the 

 coenenchyma, but occasionally existing on the flanks of the colony. 

 Coenenchyma cellular, dense. Endotheca exists. Increase by 

 extracalicular gemmation and sometimes by fissiparity. 



Distribution. — Fossil, Miocene : Sind, Asia. 



