78 

 CARD1TA. 



CHAMA ANTIQUATA. LlllHCBUS. 



Mawes Linn. pi. \%jig. 4. 

 This genus was included by Linnaeus with the 

 Chamae, from which however it essentially differs, the 

 teeth being of another form, valves always equal, and 

 the shell never affixed by its lower valve to other bo- 

 dies. It is nearly allied to the G. Venericardia, from 

 which some species are with difficulty distinguished 

 without a careful examination of the position of the 

 two teeth: it is a marine shell, and some species are 

 ^said to spiu a byssus by which the animal attaches it- 

 self to marine substances. Shell regular, equivalve, 

 inequilateral ; the greater number of species appear- 

 ing longitudinal, from the great elongation of the 

 anterior side. Hinge with two unequal teeth, one 

 short, straight, and placed beneath the umbo, the 

 other oblique, marginal, and prolonged, inserted into 

 a corresponding fossule: valves more or less strongly 

 ribbed, smooth, or imbricated ; internal margin crena- 

 ted or plaited. 



