BIVALVES CHAMA. 31 



from one inch to near a foot long. But this dimension 

 appears nothing when compared to the monstrosity of 

 the Chama Gigas or Giant Clam, which, from a quarter 

 of an inch, will advance to the enormous size of four and 

 a half feet in breadth ; and the two valves frequently weigh 

 between five and six hundred pounds. The fish or inha- 

 bitant is, of course, in the same proportion, and has been 

 known to supply more than a hundred men with food. 

 Its strength is prodigious, so much so, that it can (by clos- 

 ing its shell quickly) snap a strong cable asunder. 



Of this species there are many varieties, they are mostly, 

 however, more or less ribbed and foliated, sometimes im- 

 bricate or scaly ; the usual color of the commoner sorts is a 

 dirty white, but the rarest are those which have a fine red- 

 pink, or yellow tinge. Some of them, w hen perfect, are 

 highly prized. 



A grand mark of distinction in this genus is, that the 

 posterior slope is usually open or gaping, not unfrequently 

 having its margin crenulate. The valves are mostly ine- 

 quilateral or unequal-sided, often appearing as if deformed, 

 one protruding beyond the other. The hinge has usually 

 a callous gibbosity, inserted in an oblique hollow. 



The anterior slope is usually closed. There is one spe- 

 cies of the Chama, the Concamerata, which is in itself a 

 curiosity; for, in the interior of each valve, there is placed 

 an additional one of smaller dimensions, w hich gives the 

 shell an appearance of being double. 



The more beautiful species of this genus, are those 

 which are richly foliated or spined, — as the Chama Laza- 

 rus, Gryphoides, and Arcinella; the varieties of which 

 are sometimes highly worthy of admiration. 



It seems a principle with the Chamae, (like the Spon- 



