196 CALIFORNIA ACADEMY OF SCIENCES [Proc. 30 Ser. 



This shell is related to Chiofie pertemtis Gabb, but has not 

 the triangular outline of that species, is more produced pos- 

 teriorily, and less produced before. The hinge is fairly well 

 exposed showing its generic features unmistakably. 



Occurrence. — This species occurs with C. per tennis in the 

 Lower Miocene beds three miles east of La Panza Springs, 

 San Luis Obispo County. 



Venus (Chione) temblorensis n. sp. 



Plate XIV, Figs. 36-38. 



Shell moderate in size, 2% inches in larger diameter, i>^ inches thick; 

 sub-triangular in outline; beaks slightly anterior; incurved; lower margin 

 rounded, crenulated within, produced to an angle posteriorly; hinge margin 

 straight; surface ornamented with concentric ridges and radiating ribs. The 

 concentric ridges rise in gently fluted and ruffled folds. The radiating ribs 

 occur singly from beak to margin. 



This species is undoubtedly related to C. guidia Brod. & 

 Sow. but is ornamented with single instead of double ribs or 

 riblets, less prominent concentric folds, and generally differ- 

 ent outline. It is perhaps ancestral to the latter species. 



Occurrence. — Lower Miocene beds of Kern River and 

 Temblor. 



Cylherea (Callista) diabloensis n. sp. 

 Plate XVII, Figs. 83-85. 



Shell large, thick, obliquely cordate in outline; beaks prominent, anterior, 

 incurved; margin broadly rounded below, produced in front; cardinal 

 region widely excavated; lunule large, impressed; surface ornamented by 

 smooth concentric ridges, more or less interrupted as in C. callosa Conrad; 

 inner margins not crenulated. 



This species resembles specimens of C. callosa from the 

 California coast, but is shorter and has a greater lateral 

 thickness. Moreover it does not show the internal thicken- 

 ing of the valves as in C. callosa. 



Occurrence. — This species is not uncommon in the Coalinga 

 Beds west of Coalinga, Fresno County. 



