132 



FOSSIL ASTBROIDEA. 



Gentrale. — The most central ossicle on the abactinal surface of the disc. 

 This ossicle, together with five ossicles situated inter-radially and called the 

 " Primary Inter-radialia," are especially prominent in the young form, in which 

 they often occupy almost the whole of the aljactinal surface. Generally speaking 



/ r)e of ti)e five 

 ^^ (.primary I i-jter radialia 



„-Centra.Le 



"RadlaCiLOL 



QclraaicLU< 



S uperomarairja-Lia 



Text-hq. 'il. — Abactiniil view of a specimen of Stauramhrasli^r liilhiferus, natural size, slightly restored from 

 the specmien from Charlton, Kent, registered E. 4314 in the British Museum (Nat. Hist.). 



they can be distinguished in the adult form by their larger size, and occasionally 

 they are especially prominent, as in species of Stauranderaster (Text-fig. 34) and 

 of the recent genus Pentaceron. 



Marginalia. — In adult forms of the order " Phauerozonia," which includes 



