120 PALEONTOLOGY OF NEW JERSEY. 



The specimen from which the above description is taken is an internal 

 cast of both valves, which appears to be the original specimen figured by 

 Mr. Gabb, as above cited. I found it in the collection of Princeton College 

 labeled in Mr. Gabb's handwriting but without locality, but as Mr. Gabb 

 gives Monmouth and Freehold as the two localities from which he had ob- 

 tained it, it may safely be considered as from the Lower Marls. 



There appeai-s to be but very little difference between this species, as 

 repiesented in the individual used in obtaining the above characters, and 

 which I suppose to be the specimen used in the original description and for 

 the figure given by Mr. Gabb, and that figured on the same plate (Fig. 20) 

 as C. Delawarensis. This specimen is only an internal cast, while the other 

 specimen retains the shell, but it is proportionally longer and differs in 

 having a second ridge above the umbonal ridge. 



Formation and locality. — In the Lower Green Marls of the Cretaceous 

 at Monmouth, New Jersey. 



Crassatella prora. 



Plate XVII, Figs. 10 and 11. 



Crasstitella jirora Conrad. Am. Jour. Conch., Vol. V, p. 43, PI. I, Fig. 8. 

 Etea prora Conrad. P. A. N. Sci., Phil., 1876, p. 275. 



Shell below a medium size, transversely subelliptical when considered 

 exclusive of the projection of the beaks, but transversely broad triangular 

 if they are considered. Valves rather ventricose for the genus; beaks 

 very large, nearly central or a little nearest the anterior end, strongly pro- 

 jecting, and in the cast, the only condition in which it is known, nearljr erect 

 and moderately distant. Posterior cardinal margin regularly sloping from 

 the beaks to the narrowly rounded posterior extremity; anterior side of the 

 beaks excavated and the anterior end more broadly rounded than the op- 

 posite end; basal line broadly curved. Umbonal ridge scarcely angular. 

 Surface, as shown on the casts, marked by comparatively strong, regular, 

 concentric ridges, and marked just anterior to the umbonal angle by a pi-o- 

 portionally broad sulcation passing from near the beaks to the base. Mus- 

 cular scars distinct. 



