MOLLUSCA. 561 



it seems impracticable to recognize two distinct species of these 

 shells, and they have all been thrown together in one species,. 

 C. littoralis. Conrad originally described this species as coming 

 from the Eocene beds at Shark River, but this was doubtless an 

 error, and was one which might easily have been committed 

 considering the close stratigraphic and lithologic relations of the 

 Shark River and Manasquan formations. There is no known 

 Shark River shell which could be easily mistaken for the shell 

 under discussion, while the common casts and occasional shells 

 in the Manasquan agree quite closely with the form which 

 Conrad described. Another species which should be considered 

 in this place is C. rhombea Whitf., which occurs in the same 

 fauna, but which is considerably larger than the typical form of 

 C. littoralis; the casts of this species, except in their larger size, 

 are not very essentially different from the smaller ones, neither 

 are the surface markings of the shell inconsistent with C. littoralis. 

 It therefore seems quite possible, indeed not improbable, that C. 

 rhombea may also be considered as a synonym of C. littoralis, 

 this name having been applied merely to the exceptionally large 

 individuals. For the present, however, this species will be con- 

 sidered as distinct. 



Formation and locality. Manasquan marl, near Farmingdale 

 (138), near New Egypt (155), Shark River, Squankum (Whit- 

 field). 



Geographic distribution. New Jersey. 



Crassatellites rhombea (Whitfield). 

 Plate LXL, Fig. 8. 



1886. Crassatella rhombea Whitf., Pal. N. J., vol. I (Monog. 

 U. S. G. S., vol. 9), p. 213, pi. 27, figs. 16-19. 



Description. The dimensions of a large internal cast are: 

 length, 52 mm.; height, 43.5 mm.; thickness, 29 mm. Shell 

 subrhomboidal in outline or, exclusive of the projection of the 

 beaks, subovate, widest posteriorly; beaks large, prominent and 

 rather distant, considerably produced above the hinge-line, situ- 



36 PAI, 



