132 



FOSSIL ASTEROIDEA. 



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 abactinal surface. Generally speaking 



/ Qe of tfje five 

 /\ primary interraciialia 



x \ ** J * 



QdraciicLlLCL 



Superoma.raina.ua 



TEXT-FIG. 34. Abactinal view of a specimen of Stauranderaster bulbiferus, natural size, slightly restored from 

 the specimen from Charlton, Kent, registered E. 4344 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 Pentaceros. 



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



