FAMILY VENERID^ VENUS. 217 



GENUS VENUS. Linnaus. 



Animal oval, moderately thick, with the edges of the mantle imdulated, and furnished with 

 a row of tentacular cirri. Tubes rarely separated. Mouth small, with the labial appen- 

 dages small. Foot occasionally semilunar, not furrowed beneath. Shell solid, inequilateral, 

 subovate ; hinge with three diverging cardinal teeth in each valve ; ligament external ; 

 cordiform depressions beneath the beaks : palleal impression with a sinus. 



Venus mercenaria. 



PLATE XXVII. FIG. 276. 



(STATE COLLECTION.) 



Venus mercenaria. LiN. Syst. Nat. 1131. Russel, Ess. Jour. Nat. Hist. Vol. 1, p. 53. 



V, id. L.iM. ubi supra, Vol. 2, p. GIO. Gould, Invertebrata of Mass. p. 85, fig. 67. 



Description. Shell large, solid and jDonderous, inequilateral, subcordate ; beaks incurved, 

 and projecting forwards and inwards. Anterior area heart-shaped, and bounded by an 

 impressed line. Surface, in the old shells, with numerous coarse grooves and ridges ; in the 

 young, with concentric lamellar ridges. Epidermis very slight, and easily detached : ligament 

 stout and prominent ; posterior area obsoletely plicate. Basal margin entire, but crenulated 

 within ; anterior margin rounded ; the posterior more pointed. In the one valve, the anterior 

 tooth is largest and distant from the other two, which are oblique and contiguous ; in the 

 other valve, the two anterior teeth are united, forming a simple bifid tooth : this is most 

 striking in aged individuals. The remainder of the hinge is composed of roughened irregular 

 points, interlocking with those of the opposite valve. Muscular impressions deep, and united 

 by the palleal impression, which has an angular sinus near the posterior impression. 



Color. Externally varying from brownish white to ash-grey, and, in very old specimens, 

 with a rufous tinge, frequently deep blackish brown ; but the color appears to vary with the 

 bottom upon which they live. Within, white, with a deep violet or purple margin. 



Vertical axis, 2*0 -3" 5; transverse ditto, 3"0-4'5. Diameter, 1-8 -2'3. 



This species is the common Round Clam, much prized as an article of food, and so savory 

 in some localities as to be equally valued with the Oyster. Its aboriginal name of Quaho^ 

 has now fallen into disuse. It sells in the markets at prices varying from thirty-seven and a 

 half to sixty-two and a half cents the bushel. It abounds in all our bays, a few inches beneath 

 the bottom, from low-water mark to two or six fathom water. If taken from its bed and placed 

 on its side, it can, in the course of a single tide, bury itself six inches beneath the surface. 



From the internal purple part of the shell, the colored beads of the aborigines were formerly 

 manufactured, constituting the seawan or toampum, the specie currency of the natives. Long 

 island was formerly the great mint for the supply of this article, and hence its Mohe^an 

 Fauna — Part 6. 28 



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