SÜBCLASS II 



HEXACORALLA 



107 



Porites Link (Fig. 170). Massive or branching coralla. Calices shallow, 

 polygonal ; septa irregularly reticulated, usually twelve in number ; columella 



Litharaea ivehsterl (Bowerb.). Eocene ; Bracklesliam 

 Bay, England, a, Coralluin, natiiral size ; h, Four calices 

 enlarged. 



Fig. 170. 



Porites incrustans Reuss. Miocene ; Mo- 

 ravia. a, Tranverse section ; b, Longi- 

 tiidinal section. Both tigures highly magni- 

 fied. 



papillous, surrounded by a single cycle of pali, the latter five or six in 

 number, and not very distinct from the septal ends. Endotheca exists 

 sparingly, and may be dissepimental or tabulate, or may be mere stereoplasm. 

 Cretaceous to Recent. Thegenus b c 



Porites is one of the most im- a ^^^ . 



portant of existing reef-builders. -^^^f^s^^ ^ 



Subfamily C. 

 Alveoporinae Verrill. 



Septa composed of detached 

 traheculae, spines, or reticulated 

 lamellae, Theca perforate. Vis- 

 ceral Chamber with perforate tabulae. 



Alveopora Quoy and Gaim. 

 (Fig. 171). Massive coralla. 

 Calices small, polygonal. Septa 

 represented by detached spinous processes. 

 remotely situated. Tertiary and Recent. 



KonincUa E. and H. Cretaceous ; Europe. 



Fig. 171. 

 a,Alveoporaspongiosa'Dm\&. Recent ; Fiji Islands. Longi- 

 tudinal section of corallite showing perforate vvalls and tabulae; 

 h, Alveopora rudis Reuss. Nummulitic liniestone ; Oberburg, 

 Styria, Vi ; c, Calices, greatly enlarged. (Fig. a, after Dana ; 

 h, after Reuss.) 



Tabulae sparsely developed, 



Family 4. Acroporidae Verrill. 



Cor)iposite, branching, lobate, foliaceous, or massive coralla with corallites embedded 

 in a canaliculated and reticulated coenenchyma. Septa (6-24) compact, sometimes 

 imperfectly developed. Two long septa often projected from opposite sides and meeting 

 in the centre. 



The genus Äcropova Oken (Madrepora auct., non Madrepora Linn., 1758) 

 (Fig. 172), is an important agent in the construction of existing coral reefs, 

 and builds colonies sometimes of considerable size. It occurs sparsely in the 

 fossil State in Tertiary strata of various regions. 



Actmacis d'Orb. (Fig. 168). Massive or branching coralla. Coenenchyma 

 abundant, granulated ; septa stout, of nearly uniform proportions, columella 

 papillous ; pali in front of all the septa. Cretaceous and Tertiary. 



