180 CONCHYLIA— />/Tiir«^. 41. 



This genus forms a very natural family, distincjuished by the 

 heart-shaped form, the longitudinal ribs which are in general 

 strongly marked and prominent, and by the four teeth in each 

 valve, two of them close together and a little oblique, and a 

 remote lateral one on each side in each valve, all locking toge- 

 ther. In some of them one of the cardinal teeth in one of the 

 valves is minute and nearly obliterated ; and some have an 

 oblique rib-like denticle in addition to the lateral tooth on the 

 hinder side in the right valve, as if this tooth were doubled. 



They are in general inhabitants of sandy coasts, where they 

 lie imbedded at no great distance from the shores, and are easily 

 rooted up by any violence of surf. 



^ Valvis spinosis aut tuberculatis. 1-6. 

 The ribs armed with spines or tubercles. 



acuieatum. Cardium testd tumidd tenui obliqud, antice suhangiilafu, cos/is 

 21, anticis spinosis posticis papillosis, sulcis transversim 

 striatis. 

 Shell tumid thin and oblique, a little angular on the anterior 

 side, with 21 ribs, the anterior ones of whicii are spinous and 

 the hinder ones warty, the interstices striate transversely. 

 Tab. nost. 13. fig. 6, 7. 

 Cardium acuieatum. Linn. Syst. Nat. p. 1122. 

 Gmelin, Syst. p. 3247 

 Turton, Linn. Syst. iv. p. 201. 

 Pennant, iv. p. 187, tab. 53, fig. 1. 

 l)a Costa, Brit. Conch, p. 175. 

 Donovan, British Shells, i. tab. 6. 



