216 NEW-YORK FAUNA — MOLLUSCA. 
GENUS CYTHEREA. Lamarck. 
Animal as in Venus. Shell inequilateral, rounded. Hinge with four primary teeth in one 
valve, one of whichis remote from the others ; three in the other valve : no lateral teeth. 
CyTHEREA CONVEXA. 
PLATE XXVII. FIG. 279. a. RIGHT VALVE; B. LEFT. 
(STATE COLLECTION.) 
Cytheria convexa. Say, Jour. Acad. Nat. Sciences, Vol. 4, p. 149, pl. 12, fig. 3, 
CG; id. ConrAD, Jour. Ac. Nat. Sc. Vol. 6, p. 261. 
Cc. id. Gov p, Invertebrata of Mass. p. 84, fig. 49. 
Description. Shell moderately solid, ventricose, subcordate ; beaks elevated, directed for- 
wards. Anterior lunule heart-shaped, distinctly marked by a simple line. Surface distinctly 
marked by the stages of growth. In the left valve, the two middle teeth contiguous, divergent ; 
the one behind these, thin, lamellar; the anterior, conical, subacute: in the right valve, the 
posterior bifid. Basal margin smooth within. 
Color. Epidermis dingy white ; beneath which opake white. 
Vertical axis, 1*4; transverse ditto, 1:7. Diameter, 1:0. 
This shell occurs from New-Jersey to Maine, and perhaps farther north. It is usually 
found on muddy bottom, and is popularly known among the fishermen on Long Island as the 
Little He-clam. It was first described as a fossil species from the the tertiary of Maryland, 
by Mr. Say. 
(EXTRA-LIMITAL.) 
C. occulta. (Say, Ac. Sc. Vol. 2, p. 274) Suborbicular, thick, with numerous obtuse transverse and 
longitudinal elevated lines, nearer to each other than their own diameters: the latter not visible to the 
naked eye. Lwunule destitute of the longitudinal lines. Color, yellowish white, with a few large 
brown spots; lunule and ligament slope transversely spotted with reddish brown, Length and 
breadth, 0°5. Rare. Southern States. 
C. concentrica. (Lam. Am. sans vert. Vol. 2, p. 601. Ed. Brux. Conrap, Am. Mar. Conch. pl. 12.) 
Shell orbicular, convex, depressed, subequilateral, with numerouc crowded concentric strie; lunule 
heart-shaped, impressed, smooth; hinge with a large oblong fosset under the beaks; muscular im- 
pressions very large. Color: epidermis brownish yellow, tinged with rusty. Virginia to Florida. 
C. gigantea. (Lam. Am. sans vert. Vol. 2, p. 597.) Shell large, ovate, smooth, slightly angulated 
on the anterior side: posterior depression oblong-ovate, a little impressed on its sides and keeled in 
the middle. Teeth of the hinge compressed. Color, pale livid, with numerous bluish longitu- 
dinal rays, generally interrupted. Length, 3-25; Width, 6-0. Coast of the Southern States. 
