296 Panama Shells. 



COEBULIl>-fi. 



Hahitat. — Panama ; C. B. A. ! 



1 specimen was obtained about 2 J miles east of Panama. 



600. PoLiinomya inflata. Nor.sp. 



Shell ovate, ventricose, inequilateral, moderately inequivalve ; 

 posterior margin subtruncated between the extremities of two 

 umbonial angles, of which the upper one is indistinct ; ventral 

 margin moderately excurved; anterior margin abruptly and 

 regularly rounded: white beneath a pale brown epidermis: 

 with unequal striae of growth: beaks small: umbones vety 

 prominent, somewhat compressed : teeth small ; tooth of the 

 left valve with a medial, ridge. 



Length .7 inch ; height .57 inch ; breadth .5 inch. 



lA. less ventricose variety has the following dimensions : 



■Length .6 inch ; height .46 inch ; breadth .33 inch. 



Station. — With P. cequalis, q. v. 



Habitat. — Panama ; C. B. A.'l 



8 specimens were obtained with P. (xgudlis. 



501. Potamomya trig^onalis. Nov. sp. 



Shell solid, triangular, moderately inequivalve, subequi- 

 lateral ; upper posterior margin moderately excurved, forming 

 an angle with the:slightly excurved ventral margin j anteriorly 

 with the dorsal margin abruptly 'and regularly rounded int& 

 the ventral margin: white beneath a pale brown epidermis': 

 with fine strise of growth ; with a sharp umbonial angle defining 

 a posterior area: beaks large and prominent: Umbones promi- 

 nent, somewhat compressed : teeth large and robust; tooth of 

 the left valve with a medial ridge. 



Length .95 inch ; height .Sinch; breadth M inch. 



Station. — "With P. cequalis, q. v. 



Habitat. — ^^Panama ; C. B. A. I 



2 specimens were obtained. 



