CRETACEOtTR rOSSII.S. lf,9 



jecling- above the hinge-margin, very nearly or exactly central, and almost 

 entirely without obliquity. Surface apparently smooth, or only showing 

 very fine, obscure, concentric striae. (Hinge and interior unknown.) 



Length, 1.22 inches; height, 0.90 inch; convexity of left valve, only 

 about 0.12 inch. 



Although I have seen only casts of this species, giving no satisfactory 

 knowledge of its hinge and internal characters, from its very close similarity to 

 Cyprimeria depressa of Conrad, described from the North Carolina and Missis- 

 sippi Cretaceous rocks, I can scarcely doubt its generic identity with that 

 shell. It is quite unlike Mr. Conrad's t}q^)e-species of Cyprimeria (C. excavata), 

 so much so, indeed, that I should not have suspected it to belong to the 

 same genus. Its very close specific relations, however, as stated above, to 

 C. depressa, which has the characteristic hinge of Cyprimeria, leaves little 

 reason for doubts on this point. On comparison with good specimens of 

 C. depressa, sent to me by Mr. Conrad, I find our shell only differs (in 

 external characters at least) in having its beaks a Httle less flattened and 

 placed slightly farther forward, while its posterior dorsal outline is some- 

 what less straightened, and its anterior outline a little less narrowly rounded. 

 These, however, are not greater differences than we often see between dif- 

 ferent individuals of the same sjoecies among such shells. 



LocaUfy and position. — Whitish Cretaceous sandstone, at East Canon, 

 "Wasatch Range, Utah. 



GASTEROJ'ODA. 



NATICID^. 



Genus GYRODES, Conrad. 

 Gyhodes depressa, Meek. 



Plate 15. fif;a. 1, 1 a. 



Shell depressed so as to be about twice as, wide as high; volutions three 

 to three and a half, increasing rapidly in size ; last one widest below the 

 middle, narrowly rounded, but not angular on the under side, at least in 

 casts; spire much depressed; suture channeled in such a manner as to be 

 flattened within, owing to the presence of a revolving furrow just above it; 

 umbilicus wide and depressed-conical in form, without showing any revolv- 



