POTAMOMYA. Panama Sheik. 295 



Length 1.98 inch ; height 1.35 inch ; breadth .7 inch. 



Station. — Unknown. 



Habitat. — Panama ; C. B. A. i 

 1 valve only was found. 



498. Pandora corniita. Nov. Bp. 



Shell elongate, ovate, very inequilateral, the posterior part 

 being much longer and higher ; dorsal margin nearly straight, 

 posteriorly sharply rostriform ; posterior margin much exca- 

 vated next beneath the rostriform projection; ventral margin 

 well rounded : pearl-white : with some unequal strisB of growth ; 

 right valve with a prominent angle extending from the beak to 

 the middle of the sinus of the posterior margin ; left valve with 

 a corresponding depressed angle : beaks indistinct : umbones 

 slightly and almost equally convex. 



Length .7 inch ; height .42 inch ; breadth .11 inch. 



We adopt the appropriate name suggested by Dr. Gould, 



Station. — Unknown. 



Habitat. — Panama ; 0. B. A. ! 



Only 1 specimen was found. 



499. Potamomya sequalis. Nov. sp. *^i:^^"-i'- f~^] 



Shell subovate, nearly equilateral, slightly inequivalve ; with 

 the margin subangulated posteriorly, otherwise well rounded : 

 white beneath a pale brown epidermis : with unequal striae of 

 growth; posteriorly with an umbonial angle not very promi- 

 nent : beaks small : right umbo very prominent, both somewhat 

 compressed : tooth rather small ; teeth of the left valve with a 

 medial ridge. 



Length .78 inch ; height .66 inch ; breadth .42 inch. 



Station. — In soft impalpable mud, under a mangrove thicket, 

 near high water mark, and near the outlet of a small stream, 

 with Area tuberculosa. 



