105 



wrinkled concentrically, compressed, fragile, rounded at each end ; 

 hinge central, teeth two in the left valv§ and one in the right ; 

 epidermis pale yellowish-brown ; a broad, obsoletely elevated line 

 within passes from the hinge towards the base, and terminates 

 beyond the middle. 



Length half and inch. Breadth one inch and three-tenths. 

 Inhabits the southern shores. Cabinet of the Academy and 

 Philadelphia Museum. 



Somewhat rare. It has very much the appearace, at first sight, 

 of the young of S. carabseus, but it cannot be mistaken for it, as 

 the teeth of the hinge are invariably central, whilst those of that 

 species are anterior to the centre, and the interior of the shell of 

 that species has never the slightest appearance of a costa. 



SoLEN viRiDis. — Shell fragile, elongated, compressed, a little 

 narrowed before, slightly wrinkled concentrically, the wrinkles 

 regularly rounded towards the extremity; hinge margin nearly 

 rectilinear ; basal margin a little arquated ; anterior tip rounded , 

 posterior tip obliquely truncated, a little reflected, and rounded 

 near the base ; hinge terminal ; teeth one in each valve, each 

 having a flattened vertical surface, which turns upon that of the 

 opposite tooth ; epidermis pale green. 



Length nine-twentieths of an inch. Breadth two and three- 

 twentieths of an inch. Inhabits the southern coast. Cabinet of 

 the Academy and Philadelphia Museum. 



A common shell. The hinge is formed upon the same plan 

 with that of the ;S'. vagina and tnmcatus, but it differs from 

 those species, in being much more rounded at each extremity, 

 and in being narrowed at the anterior tip. I think it probable, 

 however, that this species has been regarded as a variety of &'■ 

 truncatus. 



SoLEMYA VELUM. — Shell remarkably thin and fragile, trans- 

 versely-oblong, rather longer at the posterior end ; hinge edentulous, 

 placed near the anterior end, with a slightly prominent cartilage, 

 and an interior elevated callus, which is fornicated beneath ; valves 

 radiated with about fifteen double lines, which are sparse towards 

 the middle of the valves ; epidermis pale yellowish-brown, extend- 

 ing much beyond the basal and lateral edges of the valves, and at 

 the hinge margin, connecting them together nearly the whole 



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