FAMILY 9. CARDIACEA. 101 



nently characteristic. It is evidently allied to that of the former genus, 

 though placed by Linnaeus amongst his Chama, and forms an accurate 

 transition from the Cardia to the Cardites. 



The shell of Isocardia may be described as being equivalve, cordate 

 and ventricose, with the umbones distant, divaricate, and turned in- 

 wards. There are two compressed cardinal teeth, one of which is re- 

 curved under the umbo, and there is also a single lateral tooth on the 

 anterior side. The muscular impression of the mantle is simple, and the 

 ligament is external. 



Examples. 



PI. LXXVIII. Fig. 1. 



Isocardia cor, Lamarck, Anim. sans vert., new edit., vol. vi. p. 445. 



Enc. Me'th., pi. 232. f. 1, a, b, c, d. 

 Chama cor, Linnaeus. 

 Cardita cor, Bruguiere. 

 Bucardia communis, Schumacher. 



PI. LXXVIII. Fig. 2. 



Isocardia Moltkiana, Lamarck, Anim. sans vert., new edit., vol. vi. 



p. 447. Enc. Me'th., pi. 233. II, a, b, c, d. 

 Chama Moltkiana, Chemnitz. 

 Cardita Moltkiana, Bruguiere. 



PI. LXXVIII. Fig. 3. (fossil.) 



Isocardia Basochiana, Defrance, Diet, des Sciences Naturelles. Sow- 

 erby, Genera of Shells, No. 7. 



CARDITA, Bruguiere. 



Testa aequivalvis, inaequilateralis, suborbicularis vel transversa, costis ab 

 umbonibus ad marginem divergentibus, margine crenulato. Cardo 

 dentibus in valva altera duobus obliquis, altero elongato, crasso, 



