FAMILY CARDIDiE — CARDITA. 205 



A small triangular tooth in the left valve, with a long grooved and oblique one along the 

 margin ; in the other valve, a long oblique tooth, occupying the pit between the teeth of the 

 left valve, and a smaller one near or upon the ligament. 



Color, white, under a thick blackish brown epidermis. 



Vertical axis, 1*0; transverse ditto, 1*1. Diameter, 0'8. 



This occurs along all the shores of Long island, and even extends to the Arctic seas. 



I suspect that Mr. Say had this species before him when he described his Venericardia 

 cribraria, which may be found on the cover of No. 5 of his Conchology, with the following 

 characters : " Longitudinally ovate, orbicular, with twenty slightly elevated ribs, more distant 

 from each other than their width, decussated by concentric almost equally elevated lines. 

 Length, 1*2; breadth, 1 • 1 . New-Jersey." 



(EXTRA-LIMITAL.) 



C. incrassata. (Conrad, loc. cit. p. 39, pi. 8, fig, 2.) Shell oblong, oblique : ribs about eighteen, 

 crenulated anteriorly. Color, light yellow, with fulvous or brown spots. Florida. 



C. tridentata. (Say, Am. Conch, pi. 40, fig. 1-5. Venericardia id. Ac. Sc. Vol. 5, p. 216.) 

 Shell suborbicular, subequilateral, thick and ponderous, with about eighteen convex ribs, cancel late; 

 obsolete on the umbo and anterior side. Inner margin deeply crenate : hinge with two diverging 

 teeth in valve, one separated by a large cavity ; on the other, a large prominent recurved tooth 

 closing into the cavity. Length, 0-25. SouthrCarolina. 



GENUS CARDIUM. Linnaus. 



Shell more or less heart-shaped : beaks prominent ; margin generally toothed or folded with- 

 in ; hinge with two oblique cardinal and two lateral teeth in each valve ; palleal impression 

 without a sinus. 



Cardium pinnatulum. 



PLATE XXII. FIG. 249. 



(STATE COLLECTION.) 



Cardium pinnatulum. Conrad, Jour. Ac. Sciences, Vol. 6, p. 260, pi. 11, fig. 8. 

 C. id. Gould, Invertebrate of Massachusetts, p. 90, fig. 57. 



Description. Shell small, thin and fragile, nearly orbicular. Ribs about twenty-six, flat- 

 tened, but becoming convex towards the base, with a series of equidistant scales almost 

 assuming behind the appearance of spines : beaks slightly elevated, often decorticated, in- 

 clining inwards. 



Color. Dingy white without ; within dull white. 



Length, 0-45. Width, 0*5. Diameter, 0*3. 



A small shell, found, but not common, only along the shores of Long island sound. 



