wrinkled concentrically, compressed, fragile, rounded at eacli end ~ 
hinge central, teeth two in the left valve 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 carabdeus, 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 truncatus^ 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 
