COI^CHYLIX—DITHYRA. 42. 193 



strongly serraie : the longitudinal strine quite invisible, except 

 when examined by a higii magnifying power, when they appear 

 to be equally distributed over the whole surface. 



42. iSOCARDlX— LAMARCK. 



Testa a^quivalcis, cordata, ventricosa ; tunbonibus remotis, 

 coitvolntis, poslice secundis. Cardo deniibus duobus com- 

 pressi's obliquis penetrantibus, tinico sub umbonein subrecurvo : 

 lalerali r^moto, antico. l/igamentum externum. 



Shell equivalve, heart-shaped, very tumid ; with the beaks remote^ 

 convolute, and both pointing to the iiinder side. Hinge with 

 two Hat oblique penetrating teeth, one of them placed under 

 the beak and a little recurved : and a remote lateral tooth on 

 the anterior side. Ligament external. 



JsocARDiA testa globoso-cordatd Iteviusculd. Cor. 



Shell globular heart-shaped, and nearly smooth. 



Tab. nost. 14. 

 Chama Cor. Linn. Syst. Nat. p. 1137. 



Gmelin, Syst. p. 3299. 

 Turton, Linn. Syst. iv. p. 244. 

 Pennant, Brit. Zool. iv. p. 214. 

 Montagu, p. 134, and Suppl. p. 50. 

 2c 



