PLATE XXX. 



Genus — Callista, Morch. 



Figs. 



1 — 6. G. plana (Sow.). Upper Greensand, Blackdown. Sedgwick Museum, 

 Cambridge. (P. 192.) 



1 (/, right valve; b, ornamentation on the postero-ventral part X 0. 



2. Hinge of right valve. The part anterior to the middle of the anterior pit is 



drawn from another specimen. 

 3 — 6. Left valves. 3 b, interior of 3a; 3c, dorsal view of 3a; 4b, anterior view 



of 4 a. 



Genus — Protocardia, Beyrich . 



7. /'. antjlica, Woods. Lower Greenland (Crackers), Atlierfield. Sedgwick 

 Museum, a, left valve X f ; h, dorsal view X 1. (P. 194.) 



