248 NEW-YORK FAUNA — MOLLUSCA. 
PHOLAS TRUNCATA. 
PLATE XXXIV. FIG. 223.4. 3. 
(STATE COLLECTION.) 
Pholas truncata. Say, Jour. Ac. Nat. Sciences. Vol. 2, p 321. 
Pca. WueEat ey, Catalogue of Shells United States, p. 4. 
Description. Shell subpentangular ; anterior obtusely rostrated, wedge-shaped in the middle ; 
posterior margin broadly truncated at the tip. Valves transversely wrinkled, crossed by 
strie, muricated (particularly on the anterior side) with small erect scales which are not 
arched beneath ; posterior margin without strie, and mutic, Hinge-callus without cells: a 
small tooth on the inner margin, projecting backwards ; the dentiform process curved, promi- 
nent, flat, slender. 
Vertical axis, 0°'7; transverse ditto, 1°7. 
This appears to be a common shell on the southern coast, but is rare with us. It has been 
found imbedded in peat bogs at Sachem’s head (Connecticut), at Throg’s neck (Westchester 
county), at Glasshouse point above the city, and at Staten island, (Richmond county). 
(EXTRA-LIMITAL.) 
P. costata, Lin. (Dxrsuayrs, Conch. pl. 3, fig. 10. Gown, l.e. p. 27.) Shell very large, thin, 
inflated, with strong crenulate radiating ribs about half an inch apart on the basal margin, becom- 
ing abruptly closer, armed with small vaulted scales formed by transverse striz passing over them. 
Color, white. Vertical axis, 2+0; transverse, 7-0. Common on the shores of the Southern 
States. An extensive bed of dead shells has been found at New-Bedford, Mass. 
P. cuneiformis. (Say, Ac. Sc. Vol. 2, p. 322.) Wedge-shaped; anterior margin nearly closed, 
transversely truncated from the hinge; posterior margin with a rounded lip; a deep furrow from 
the beak to the middle of the basal margin, impressed within. _ Surface with transverse undulating 
strie, with elevated minutely crenate lines. Hinge-callus forming a cavity before, and without 
cells; dentiform process filiform, incurved; hinge-plate ovate-triangular, with a short projecting 
angle on the anterior middle, and subacute behind. Color, white. Vertical axis, 0+45; transverse, 
0:8. Occurring frequently in old wood. Southern Coast, 
P. oblongata. (Say, Ib. Vol. 2, p. 320.) Shell thin, transversely much elongated: basal and hinge 
margins nearly parallel; ends rounded. Valves transversely and longitudinally striated; the strise 
muricate, and elevated into cost on the anterior side, which are more prominently and densely 
muricated. Hinge-callus minutely striated transversely and longitudinally, and with about twelve 
cells, anterior to which is a recurved margin of the shell, forming a cavity; dentiform process 
dilated, incurved, spoon-shaped, emarginate behind, and irregularly truncate at the tip. Vertical 
axis, 1+2; transverse, 4°4. Carolina, Georgia, and East-Florida. 
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