FAMILY VENERIDZ — VENUS. 219 
This beautiful little shell, which has been dredged from the East river near Blackwell’s 
island, was for a long time considered as the young of the common round clam. Col. Totten 
first detected its specific identity. It occurs abundantly on all the sandy shores of Massachu- 
setts, but its extreme northern and southern limits are not yet known. 
VENUS PRASOPARCA. 
(STATE COLLECTION.) 
Venus preparca. Say, Journ. Acad. Nat. Sciences, Vol. 2, p. 271. 
v. notata, var.?’ GouLD, Invertebrata of Mass. p. 87. 
Description. Shell ovate, with numerous elevated subacute parallel concentric lines, which 
subside into mere wrinkles near the suture of the ligament-slope ; interstitial spaces plain : 
ligament-slope flattened, margined by an acute line. Anterior margin with an obsolete longi- 
tudinal very obtuse undulation, which gives the tip of this margin a slightly truncated appear- 
ance ; areola cordate, elevated at the suture: lower and posterior margins crenulated, the 
crenule extending along the edge of the areola to the beak. In advance of the anterior ter- 
mination of the ligament-groove of the left valve, is another distinct groove, which receives 
the edge of the corresponding margin of the other valve. 
Color, white, immaculate ; within, white or yellowish white. 
Vertical axis, 1'0 — 1°5; transverse ditto, 1°5 — 2°2. 
This shell occurs frequently along our beaches, and is usually taken for the young of the 
V. mercerania. Dr. Gould states that it seems to be same as V. notata, in which merely the 
zigzag lines are wanting. It seems to me more widely transverse than either. 
(EXTRA-LIMITAL.) 
V. inequalis, Say. Shell subcordate, longitudinally sulcated: lines numerous, obsolete on the anterior 
margin; behind the middle, bifid, and alternating with smaller single ones: concentric distant 
lamellar bands but little more elevated than the longitudinal lines. Anterior margin subangulated ; 
within, the margin crenate; crene obsolete on the anterior margin and rear. Hinge on the poste- 
rior margin. Length, 1-0; width, 1-2. Coast of New-Jersey and Maryland. 
V. elevata. (Ip. Ib. p. 272.) Shell subcordate, longitudinally sulcate: sulci equal, numerous, dense ; 
on the anterior submargin sparse: concentric elevated remote lamellar bands. Anterior margin 
subangulated at the tip; within, margin crenate; crene obsolete on the anterior margin, and near 
the hinge on the posterior margin. Length, 0°8; breadth, 0+9. Southern coast. 
V. mortoni. (Conran, Ib. Vol. 7, p. 251.) Shell very large, cordate, inflated, thick and ponderous, 
with prominent recurved concentric lamine, more elevated on the anterior and posterior margins ; 
ligament-margin arcuate. Umbones prominent; lunule large, cordate, defined by a deep groove; 
28* 
