MADREPORARIA APOROSA. 



265 



boniferous, may be looked upon as early types of the Turbiiiolidaz, 

 as, perhaps, Petraia and Polycoslia may also be. Professor Duncan 

 further regards the Devonian genus Batter sbyia and the Carboniferous 

 Heterophyllia as representing a special group of Aporosa allied to the 

 Astrceidcz. In the Secondary and Tertiary deposits the Aporose 



Fig. 140. — Caryophyllia (Cyathina) Bowerbanki, from the Gault (Cretaceous). The left-hand 

 figure represents a specimen imperfect above, and enlarged, showing the tuberculated costse. 

 The right-hand figure is a magnified cross-section, showing the septa and pali. (After Milne- 

 Edwards and Haime.) 



Madreporarians are represented by a vast number of types, which 

 do not essentially differ in plan of structure from existing forms. 



The Madreporaria Aporosa are divided into the following 

 families : — 



Family 1. Turbinolidce. — In this family the corallum is generally 

 simple, or when compound is destitute of a ccenenchyma. The wall 

 is solid and imperforate, and the septa are in the form of lamellae, 

 often granulated on their sides. The inter septal loadi are open from 

 top to bottom, no endothecal structures in the form of dissepiments 

 or synapticulae being developed. A few Palaeozoic Corals (such as 

 Du?icanella and Cyathaxonid) may be referred here, but the family 

 is mainly Secondary and Tertiary. 



The number of forms included in the TiwbinolidcB is so large, that only 

 a few of the leading types of the family can be here referred to in the 



