214 PALAEONTOLOGY OF CALIFORNIA. 



abrupt truncation. Surface ornamented by fine, numerous, regu 

 lar, concentric lines. Lunule bordered by a fine impressed line. 



Figure, magnified to nearly twice natural size. 



Locality: A single specimen was found by Mr. Mathewson, in Division A., 

 west of Martinez. 



This shell resembles very closely Orassatella Uvasana, Con., in general outline. 

 It is very much thinner, however, is more produced posteriorly, the anterior end 

 is not so deeply excavated under the beaks, is more compressed, and the surface 

 ornaments and lunule are entirely different. 



I have not succeeded in uncovering the whole of the hinge of the specimen 

 described; but, from what I can see, it seems to resemble more nearly that of 

 Chione than any other genus. I have, therefore, referred it so provisionally. 



TAPES, Megerle. 



? T. CEETACEA, n. 8. 

 PL 32, Fig. 283. 



SHELL large, robust, quadrate; cardinal and basal margins 

 nearly parallel ; beaks small, approximate, anterior ; anterior end 

 broadly rounded ; posterior convexly subtruncated. Surface con 

 vex above, flattened towards the base, marked only by lines of 

 growth. 



Figure, natural size. 



Locality : North of Corral Hollow, Alameda County. 



CRASSATELLA, Lam. 



C. UVASANA, Con. 



PL 32, Fig. 284. 

 (C. Uvasana, Con. Pacific E. R. Rep., vol. 5, p. 320, pi. 2, fig. 5.) 



SHELL thick, robust, triangular, convex; beaks broad, promi 

 nent, and strongly incurved; cardinal margin sloping a little con 

 vexly to the posterior end, which is subangular; anterior end 

 broadly rounded below, deeply excavated above; lunule large, 



