260 Panama Shells. ARCID^E. 



Area mutaUlis Orb. Voy. Amer. Merid. Moll. p. 638. 1846. 



Station. Under stones ; Cuming ! Sowerby : also Reeve. 

 Our specimens were found under stones and in the crevices 

 of rocks, near low water mark. 



Habitat. I. of Plata; Cuming! Sowerby: also Eeeve : also 



Orbigny. 



"West Columbia ; Hanley. 

 I. of Plata ; Jay. 

 Panama and Taboga ; C. B. A. ! 



70 specimens were collected ; among them are some remark- 

 able varieties of form. 



419. Area (Bysoarca) pholadiformis. Nov. sp. 



Shell extremely elongated, subcylindrical, contracted ante- 

 riorly, very inequilateral : inferior margin a little irregular, 

 somewhat excurved, scarcely gaping for the passage of the bys- 

 sus : posterior margin very oblique, moderately excurved : ante- 

 rior margin well rounded : dingy white : surface very finely and 

 closely fimbriated, with the concentric ridges larger except above 

 the posterior angle of the umbo, on which the concentric ridges 

 are lamellar : with the intersections nodular and deeply marked 

 beneath with the arcuate striae of growth : umbones flattened, 

 with a very prominent and very oblique posterior angle, from 

 which the radiating ribs divaricate: beaks small: area of 

 ligament linear, nearly concealed : margins of the interior finely 

 crenulate ; teeth obsolete at the middle of the series, at the 

 ends divaricate. The sculpture is like that of A. divaricata 

 Reeve. 



Length 1.25 inch; height .53 inch ; breadth .48 inch. 



Station. In soft stones, near low water mark. 



Habitat. Taboga ; C. B. A. ! 



2 specimens of thi? extraordinary shell were obtained. 



