24 PALAEONTOLOGY OF CALIFORNIA. 



concentric ribs, abrupt on the upper side, sloping towards the 

 base. 



Figure, natural size. 



Locality and position: A single specimen collected by Prof. Whitney, near Mar 

 tinez. Appears to be from the Miocene formation, from the character of the 

 matrix. 



Related to C. foveolata, Sby. ; but differs in not being so produced behind, and in 

 being more regularly striate. 



CALLISTA, Poli. 

 C. VOYI, n. s. 



PL 6, Fig. 41. 



SHELL broad, inequilateral ; beaks in advance of the middle : 

 cardinal margin nearly straight and sloping; anterior end very 

 much produced, rounded and narrow ; posterior end obliquely 

 truncated; base broadly and regularly rounded. Surface marked 

 by numerous irregular and rather strong lines of growth. 



Figure, natural size. 



Locality and position: From the Miocene or Pliocene near Humboldt Bay, he- 

 low Bear River, Humboldt County ; collected by Mr. Voy. 



This fine shell belongs to the type of C. gigantea, and is the only species of this 

 group yet found in California. From gigantea it is easily distinguished by its 

 broader posterior end, by the anterior end being shorter, more sloping above and 

 narrower. The character of the surface is also different. 



DOSINIA, Scopoli. 

 D. STALEYI, n. s. 



PL 7, Fig. 42. 



SHELL subcircular, thick, very inequilateral; beaks large, 

 prominent, anterior. Lunule faint, rather large, slightly sunken. 

 Surface smooth, marked by a few lines of growth near the base. 

 Hinge robust. 



