381 



sloping somewhat concavely and obliquely downward in front of the 

 beaks, and rather convexly as well as obliquely behind them ; ventral 

 margin very slightly convex, nearly straight in the middle ; umbo and 

 beak nearly median ; posterior side not much longer than the anterior. 



Surface concentrically and rather coarsely striated. 

 Hinge dentition and muscular impressions unknown. 



Fig. 25. — Cyprina Denmnncnsis. Outline of the only specimen collected, about 

 five sixths of the natural size. 



West side of Denman Island, Dr. C. F. Newcombe, 1896 : the large right 

 valve figured, which, unfortunately, has the umbo and lateral margins con- 

 siderably eroded. The specimen, however, seems to indicate a species of 

 Cyprina that differs alike from C. occidentalis of the Cretaceous rocks of 

 the Queen Charlotte Islands, from C. Dalit, White, of the Cretaceous 

 rocks of Alaska, and from the C. ovata, var. alta, of the Pierre-Fox Hills 

 or Montana formation of Assiniboia and Alberta, in its much larger size, 

 more nearly median beaks, and much straighter ventral margin. 



