1855.] 267 



Miocene Species. 

 ANOMJA, Lin. 



A. subcostata. Obtusely ovate from base to back; lower valve thick, with 

 interrupted somewhat tubercular radii ; upper valve thin, radii obsolete or 

 wanting. Height l in. 



Locality. Colorado Desert. Dr. Heermann. Shell silicified. 



OSTREA, Lin. 



O. Heermanni. Very irregular in form, thick, ovate and subfalcate, often 

 dilated; lower valve shallow, the exterior very irregular, with large distant 

 angular radiating ribs, and with pits or cavities ; cartilage pit broad and oblique ; 

 upper valve flat or concave, with a profoundly irregular surface. Height 6 

 inches. 



Locality. Colorado Desert. Dr. Heermann. Shell silicified. 



MERC EN ARIA, Schum. 



M. perlaminosa. Obliquely-cordate, very inequilateral, with numerous, pro- 

 minent, recurved, lamelliform, concentric ribs; lunule cordate, not deeply 

 impressed; posterior margin truncated, direct ; within purple from the pallial 

 impression to the base; margin finely crenulated. 



Locality. California. Dr. Heermann. 



Allied to M. Ducatellii, Con., of the New Jersey ?*Iioeene. 



PECTEN, Lin. 



P. Heermanni. Suborbicular, thin, compressed; ribs about 21, square, 

 smooth; ears moderate in size. 



Locality. California. Dr. Heermann. 



Allied to P. eboreus of the Virginia Miocene, but very distinct. Only two 

 inferior valves were obtained. They are slightly convex. 



DIADORA ; Gray. CEMORTA, Leach. 



C crucibuliformis. Oval; height about two-thirds of the length; apex, 

 central, curved towards the anterior margin; ribs 20 or 21, distant, narrow, 

 prominent ,* interstices with each a fine line. 



Locality. California. Dr. Heermann. 



Many authors adopt Leach's name for this genus, but I suppose it was unpub- 

 lished at the time Gray's appeared. 



PANDORA. 



P. bilirata. Oblong, very inequilateral, contracted anteriorly, convex me- 

 dially ; posterior side with two distant carinated lines towards the hinge margin 

 which is straight and not oblique; posterior extremity truncated. 



Locality. Occurs w.th the preceding. 



CARDITA. 



C. occidentalis. Subtriangular, equilateral? ventricose; ribs 15, rounded, 

 wider than the interstices, and regularly granulated by transverse lines. 



Locality. Occurs with the preceding. 



Allied to C. , of the San Pedro recent formation, but proportionally 



more elevated and having more prominent granules. 



ASTARTE, Sow. 



A. Thomasii. Triangular, not ventricose, inequilateral; ribs concentric, 

 robust, recurved ; concentric lines more or less marked, minute; towards the 

 posterior end the ribs suddenly become obsolete; extremity truncated, nearly 



