174 NEW-YORK FAUNA — MOLLUSCA, 
on both sides near the hinge. Surface with numerous imbricated strie radiating from the 
beaks, with a few distant concentric strie, which, in old age, become deep sinuous furrows, 
the radiating striae becoming obsolete. Beaks small, distinct, contiguous. Hinge-margin 
straight : ligament inserted into a sublinear pit, black, greyish on the sides nearest the base 
of the pit; within smooth, polished. Muscular impression distinct. 
Color. Convex valve pale reddish (on the beaks reddish brown), with pale radiating lines 
and deeper red concentric circles; lower valve yellowish or tinged with reddish ; - within 
polished white. 
Length, 4°0-5°0. Width, 4°5 —5°5. 
The plate represents the upper valve of a moderate sized shell : the old shells are frequently 
eroded and pierced by other marine animals. Specimens have been taken by dredging in 
deep water off Sandyhook, where it appears to be not uncommon, as many were taken at 
the same time. I have also obtained them in fifteen fathom water, on the south coast of 
Long island : the convex valves were all more or less deeply sculptured and eroded by marine 
parasites. They are represented to be palatable as food. 
(EXTRA-LIMITAL.) 
P. purpuratus, Lam. (P. dislocatus, Say, Ac. Sc. Vol. 2, p. 260; Am. Conch. pl. 56, fig. 2. Con- 
rap, Am. Mar. Conch. p. 10, pl. 2, fig. 2.) Shell suborbicular, with 20 — 22 elevated rounded 
ribs and numerous concentric wrinkles: no longitudinal stria; ears subequal; hinge margin 
straight in each valve. Color, whitish tinged with yellow or reddish, with a few narrow transverse 
interrupted and dislocated reddish undulated lines, and 5 — 6 obscure spots on the margin at the base 
of the ears. Length, 15-20; width, 1°6-—2°2. Southern coast. 
P. ornatus, Lam. (Conrap, Mar. Conch. pl. 2, fig. 3.) Shell small, somewhat longer than broad, 
subequivalve, compressed: ribs 30 — 36, alternately smaller and subscabrous; one of the ears very 
small. Color, pale yellowish, with red angular spots. Length, 1*5: width, 1*3. Florida. 
P. nodosus, Lam. (Conran, ib. pl. 2, fig. 2.) Shell with nine thick rounded ribs, and strong 
radiating strie; ribs with large hollow vesicles. Color, reddish brown, orange or white. 
Length and breadth, 2-0 -5:°0. Florida. 
P. varius. (Turron, Conch. Ins. Brit. p. 214.) Shell oblong, nearly equivalve, with from twenty- 
five to thirty compressed ribs more or less clothed with concave spines. Color, exceedingly variable, 
Length, 2-0. Found by Mr. Lesueur on the northern coast. 
Genus Pricatuna, Lam. Animal unknown. Shell inequivalve, without ears, attenuated at the base; 
upper margin plaited, rounded; beaks unequal, and without external facet. Hinge with two 
strong striated teeth on each valve; a pit between the two teeth for the ligament, which is 
entirely interior. 
P. ramosa. (Lam. An. sans vert. Vol. 3, p. 6.) Shell oblong-triangular, very stout and solid, with 
numerous large ramified folds, Color, white, spotted with ferruginous marks. Length, 35 — 40 
millimetres. 
