214 PALEONTOLOGY 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 Crassatella 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 sj>ecimen 

 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. CRETACEA, n. 8. 

 PI. 32, Fig. 283. 



SnELL 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 tbe base, marked only by lines of 

 growtb. 



Figure, natural size. 



Locality : North of Corral Hollow, Ahuneda County. 



CRASSATELLA, Lam. 

 C. Uvasana, Con. 



PI. 32, Fig. 284. 

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



Shell tbick, robust, triangular, convex; beaks broad, promi- 

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

 vexly to tbe posterior end, wbicb is subangular; anterior end 

 broadly rounded below, deeply excavated above; lunule large, 



