C HAP. XIV. 



BIVALVES: 

 CHAM A; Clamp, Clam, or Gaper. 



Q. How am I to distinguish the Chama from 

 Bivalves in general ? 



A. By its coarse shell, and hinge furnished 

 with a gibbous callosity, obliquely inserted in 

 an inclined hollow. Also by observing that this 

 callosity, or tooth, is either simple or crenate 

 (blunt), and that it is occasionally double or 

 triple. 



Q. These characteristics hardly appear suf- 

 ficiently descriptive. 



A. I will notice some other peculiarities, 

 which will enable you easily to distinguish the 

 Chama. Some species of this genus are trun- 

 cate, and gape on the posterior margin ; and 

 though all do not so, they agree in being equi- 

 valve and sub equilateral (the anterior and posterior 

 parts of the shell nearly equal), in having recurved 



