244 CARDIUM. 



SPINY-KEELED HEART COCKLE. 

 PL 59./, 1, 2. Mr. Sowerby. 



53. Cardiutn Cardissa. C testa cor data, vahulis compressis, dentato cari- 



natis, natibus approximates. Linn. Syst. Nat. ed. 12. p. 1121. 



Linn. Gmel. p. 3245. 

 Shell heart-shaped; valves compressed, toothed on the keel; beaks close 



together. 

 Testa cordiformi, utrinque compressa, umbonibus carinatis, natibus in- 



curvis, super impositis. Brug. Encyc. Meth. Hist. Nat. 6. p. 208. 

 List. Conch, pi. 318. f. 155. Rumph. Mus. pi. 43. f. E. Gualt. Test. 



pi. 84. f. B. C. D. D'Argenville, pi. 23. f. 1. Favanne Conch. 



pi. 51. f. E. 2. Born. Test. pi. 2. f. 17, 18. Chem. Conch. 6. pi. 14. 



f. 143, 144. Encyclop. Method, pi. 293. f. 6. a. b. 



This is a completely heart-shaped shell, remarkable 

 for its elegant form, and the singular flatness of its 

 valves. It is of a whitish colour, sometimes variegated 

 with milky spots, and sometimes, though more rarely, 

 with pale rose colour. The valves are as thin as paper, 

 and edged with a spiny keel ; the anterior face of the 

 shell is concave below, and convex above, with a small 

 heart-shaped depression, just beneath the summit, con- 

 taining the cardinal ligament. There are about thirteen 

 longitudinal ribs on the anterior side, with their corre- 

 sponding grooves. The posterior face is uniformly 

 convex, except close to the margin, where the valves 

 insensibly flatten; there are twelve ribs on this side, 

 and as many channels, which are flat, finely striated, 

 and armed, except the four exterior, with minute points, 

 which roughen the shell ; there are four teeth in each 

 valve. 



Inhabits the Indian ocean, the coas of Coromandel, 

 and the Persian Gulf. 



