224 



ECHINODERMATA ECHINOIDEA 



SUB-BRANCH III 



(a) Cidaris, s. str. I A mb coronal plates five to eight. Amb more or less undulating ; pairs 

 of pores rather close, separated by a nodule or ridge. Primary tubercles perforated and 

 crenulated. 



(b) Rliabdocidaris, Desor (Fig. 359). Test large and swollen. Poriferous zones wider than 



FIG. 356. 



Cidaris coronata, Goldf. Upper Jura (y) ; Hossingen, Wurtemberg. A, Dorsal aspect of test with perfectly 

 preserved apical system. B, Profile. C, Portion of Amb, magnified. D, Partially restored view with spines 

 attached. 



ill Cidaris, the two pores of a pair being distant and conjugated. Amb in general straight. 

 Tubercles large, strongly crenulated, and more numerous than in Cidaris. Spines very stout, 



Fro. 357. 



Cidaris tribuloiiles, Lnm. Recent. Enlarged view of peristome 

 showing plated covering. 



FIG. 358. 



Cidarid spines. A, 

 C. alata, Ag. B, C, 

 dorsata, Braun. Trias ; 

 St. Cassian, Tyrol. C, 

 C. florigemma, Phill. 

 Coral Rag ; Wiltshire. 



some cylindrical or prismatic, often spiniferous. Chiefly Jura and Cretaceous ; less common in 

 Tertiary and Recent. 



