TRIBE CARDIACEA. 139 



under a yellowish epidermis, white spotted with brown and red ; 

 with thirty-two ribs of which the posterior are biangulated and 

 crenated, the central smooth and biangulated, the anterior rounded 

 smooth and armed with oblique tubercles. 2^\. . 1-iJ. — W. Indies. 



C. Maculatum. C. I. f. 18. — C. Maculosum. Sow. Z. P. 

 1833. Oboval, subventricose, anteriorly somewhat sloping, marbled, 

 with radiating ribs of which the posterior ones are flattened and 

 their edges crenated, the anterior ones rounded : the interstices 

 posteriorly very narrow. 2^- . . 1 t 3 q. — California. 



C. Enode. Sow. Jun. Z. P. 1840.— C. L f. 51. Oval, ven- 

 tricose, anteriorly subexpanded, most strongly toothed ; pale ful- 

 vous with rosy bands ; within white, yellow under the umbones, 

 purple at the margin : with thirty-eight flattened ribs, the posterior 

 slightly crenated, the interstices very narrow. 2J-. . 2-^. — Ceylon 



C. Nuttalii. Conr. Journ. A. N. S. Phil. 7. p. 229. t. 17. 

 f. 3. Ovate triangular, ventricose, thick, with thirty-four regu- 

 larly rounded ribs with prominent arched striae ; umbo narrowed, 

 summit very prominent ; anterior slope much depressed ; anterior 

 margin straight, oblique, simply undulated ; ligamental margin de- 

 clining, ventral edge regularly arcuated ; white with a yellowish 

 brow r n epidermis : lateral teeth thick and prominent, margin pro- 

 foundly serrated. Length 3 J. — N. California. 1 



C. Quadragenarium. Conr. Jour. A, N. S. Phil. 7. p. 

 230. t. 17. f. 5. Cordate, subequilateral, ventricose, thick, with 

 forty to forty-two prominent subangular ribs, which are flattened 

 at the side and armed with a row of small tubercles ; these 

 largest on the posterior side where they are seated on the middle of 

 the ribs, though elsewhere on the anterior angular margin ; umbo 

 broad and prominent ; beaks not oblique, tubercles elevated on the 

 anterior slope : pale yellow with fulvous spots and zones : anterior 

 margin direct, deeply serrated. Length 3. — U. California. 

 Allied to Asiaticum. 



C. Californianum. Conr. Jour. A. N. S. Phil. 7. p. 229. 

 t. 17. f 4. Suborbicular, ventricose, thickish, with thirty-four 

 prominent slightly flattened ribs roughened by prominent arched 

 striae which become obsolete on the back of the ribs in the middle 

 of the valves : summit of the umbo prominent, beaks oblique ; 

 yellowish with pale red spots : margin deeply serrated : anterior 

 margin direct and undulated. Diam. 1 J. — U. California. 



1 Compare the young of Nuttalii, with the C. Arcticum. Sow. 

 Jun. Z. P. 1840. — C. I.f. 26. Oval, compressed, subequilateral ; 

 with twenty-seven angular subcrenulated ribs ; the epidermis thick 

 and olive brown (becoming by age eroded at the umbones) ; ligament 

 elongated : central teeth obsolete, lateral distant. 1| . .14 1 . — 

 Arctic Ocean. 



