230 



ECHINODERMATA ECHINOIDEA 



SUB-BRANCH III 



extended into the depressed posterior lAmb. Pairs of basal plates separated 

 by the antero-lateral radials, the fifth basal absent. Cretaceous. H. libycum, 

 Cotteau. 



Codiopsis,' Ag. (Fig. 369). Primary tubercles of both areas small, smooth, 

 nearly equal in size, and only occurring actinally and for a short distance 

 toward the ambitus. Pairs of pores uniserial. Cretaceous. 



Cottaldia, Desor. Cretaceous and (?) Recent. Pleurodiadema, de Loriol. 

 Jura. Magnosia, Michelin. Jura and Cretaceous. 



Sub-Family B. DIPLOPODIINAE. 



Ambulacral plates compound ; pairs of pores biserial. 



Diplopodia, M'Coy. Amb narrow, with two vertical rows of perforate and 

 crenulate primary tubercles. Pairs of pores in double vertical series near the 

 poles, uniserial at the ambitus. Jura and Cretaceous. 



Pedinopsis, Cotteau. Cretaceous. Phymechinus, Desor. Jura. 



Sub-Family C. PEDININAE. 



Ambulacral plates compound; pairs of pores triserial. 



Pedina, Ag. Amb narrow, poriferous zones wide. Both areas with two 

 vertical rows of small, perforate, primary tubercles. Upper Jura. 



Una, Cott. Like the preceding, but with larger primary 



FIG. 370. 



Stomechinus lineatus, Goldf. sp. Coral Rag ; Sontheim, Wurtemberg. A, Side-view of test, 

 of actinal surface. 



B, Portion 



Upper 



tubercles, which are present in the Amb near the ambitus only. 

 Jura. 



Micropedina, Cott. Amb with several, and lAmb with numerous vertical 

 rows of very small primary tubercles. Cretaceous. 



Stomechinus, Desor (Fig. 370). Distinguished from Pedina by its wider 

 Amb, and imperforate, non - crenulate, primary tubercules. Secondary 

 tubercles and granules often present. Jura and Cretaceous. 



Codechinus, Desor. Tubercles very small, plain, Irregularly distributed. 

 Cretaceous. 



Polycyphus, Ag. Jura. Astropyga, Gray. Recent. 



