290 



ECHINODERMATA—ECHINOZOA 



PHYLUM IV 



üuhgenus Bochmostoma Duncsin {Trematopygus d'Orb.). Like the preceding, but with 

 oblique peristome. Cretaceous ; Europe and Nortli America. 



Botriopygus d'Orb. Cretaceous. Ilariona Dames. Eocene. 



Family 2. Cassidulidae Agassiz. 



Test variable in shape. Ämhulacra petaloid, sub-petaloid or apetalous dorsally, 

 and with crowded doubling of the pairs of pores dose to the peristomal margin, 

 forming with the single, swollen and ornamented interamhulacral peristomal plates a 

 floscelle. Jura to Recent. 



Test small, oblong, depressed, convex 

 dorsally, flat actinally. Amh narrow, 

 sub-petaloid, not closing ; pores con- 

 tinued from the middle part to the 

 well-developed floscelle. Peristome 

 eccentric in front ; periproct supra- 

 marginal, longitudinally elongated. 

 Cretaceous and Eocene. 



Subgenus Rhyncopygus d'Orb. Periproct 

 transversely eloiigate, with overhanging 

 rostrum. Cretaceous to Recent. 



Subgenus Pygorhynchus Ag. Test con- 

 cave actinally, with long petals. Peris- 

 tome and periproct longest transversely. 

 Cretaceous to Miocene. 



Cassididus Lam. (Fig. 409). 



Fig. 409. 



Cassidulus lapis-cancri Lam. A, Test in three positions. 

 B, Floscelle, enlarged. 



Stigmatopygus d'Orb. Cretaceous. Eurhodia d'Arch. and Haime. Eocene. 

 Paralampas and Neocatopygus Duncan and Sladen. Eocene. Catopygus Ag. 

 Cretaceous. Studeria Duncan. Tertiary and Recent. Phyllohrissus Cotteau. 

 Jura and Cretaceous. 



Clypeus Agassiz. Test large, low, nearly flat actinally. Amb wide, 

 petaloid, not closing dorsally, narrow at the ambitus and actinally. Pore- 



Pygurus royerianus Cotteau. Klinmeridgian ; Tönnjesberg, near Hanover. A, B, Dorsal and ventral views 

 of test, 3/4 natural size. C, Apical System, enlarged. D, Ambulacral plates, magnified. 



pairs in the petaloid parts with the inner pore small and circular, the outer 



