140 PALAEONTOLOGY OF CALIFORNIA. 



small, regular, rounded ribs, with sometimes finer ones interpo 

 lated. 



Figure, slightly magnified. 



Locality : Northeast of MartiSez; San Diego (Div. B.); and Curry's, south of 

 Mount Diablo (Div. A.). 



EMARGINULA, Lam. 



E. RADIATA, 11. S. 

 PI. 21, Fig. 102, and 102 a. 



SHELL subelliptical, moderately elevated ; apex a little in ad 

 vance of the middle, slightly curved. Surface marked by about 

 eighteen rather large radiating ribs, with occasional small inter 

 mediate ones; these are crossed by a few irregular, concentric 

 lines. Emargination narrow and rather deep; the corresponding 

 ridge sharply defined and nearly square. 



Length, .3 inch; width, .18 inch; height, .12 inch. 



Locality : Texas Flat, Placer County. 



I have seen hut a single specimen of this rare and beautiful little shell. It is 

 in the collection of the California Academy of Natural Sciences. 



PATELLA, Linn. 

 P. TRASKII, n. s. 



PL 21, Fig. 103. 



SHELL depressed, subelliptical; apex subcentral; height vari 

 able. Surface marked by from twelve to fourteen radiating ribs 

 with intermediate lines, from one to three in number ; these 

 are crossed by irregular lines of growth. Margin gently undu 

 lated, the ends of the ribs being more prominent than the inter 

 spaces. Muscular impression horseshoe-shaped; ends connected 

 by a sharp impressed line. 



Figures, natural size. 



Locality: Texas Flat, Placer County (Division A.). 



