100 
iially striated with nnmeroiis, equal, parallel, regular impressed 
lines, not visible to tlie unassisted eye, and obsolete on the poste- 
rior margin 3 basal edge within crenate 3 color pale-livid, with two 
longitudinal whitish rays before the middle, both within and with- 
out,. 
Yar. a. Whitish. Var. h. Yellowish. Breadth from half an 
inch to three-fifths. Inhabits the coasts of New Jersey and Mary- 
land. Cabinet of the Academy and Philadelphia Museum. 
Y ery numerous under the surface of the sand, which is exposed 
at the recess of the tide. A wave, by removing the surface of the 
sand, exposes a great many individuals to view, at its refluence 3 
these immediately penetrate the sand, and before the recurrence of 
the surge they are concealed. 
They are preyed upon by several shore birds and fish 3 the drum 
(^Scisdna chromii) and sheep’s-head (^JSpurus oviceplialus) are 
sometimes caught in the surf in considerable numbers, whilst in 
pursuit of them. 
xImphidesma ORBictiLATA. — Shell orbicular, somewhat com- 
pressed 3 beak nearly central, and a little prominent 3 posterior 
slope a little concave near the beak 3 lunule small 3 valves slightly 
wrinkled transversely 3 anterior submargin with an obsolete very 
obtuse undulation, and with a few longitudinal obsolete lines 3 
color dirty white 3 hinge with two lamellar teeth, the posterior one 
placed near to the primary tooth, and shorter than the anterior 
one 3 interior ligament cavity profound, fusiform, parallel with the 
anterior slope, originating at the extreme tip of the beak, and ter- 
minating nearly opposite to the middle of the anterior lamellar 
tooth. 
Length one inch and one-tenth. Breadth one inch and one- 
tenth. Inhabits the coast of Georgia. Cabinet of the Academy 
and Philadelphia Museum. 
Appears to be a rare species 3 the largest I have seen is one inch 
and two-fifths in breadth. 
Amphidesma jsqualis. — 'Shell orbicular, slightly oblique, 
polished, white, with very minute and numerous concentric 
wrinkles near the margin, which are obsolete on the disk and 
umbo 3 lateral teeth none 3 primary teeth two in the left valve and 
one in the other 3 interior ligament cavity subfusiforni, as long as 
the exterior ligament. 
