CONCHIFERA OR BIVALVES. 103 



This genus, which only possesses one species, 

 the Iridina exotica, is found in the rivers of 

 warm climates, the Nile amongst others ; the 

 shell is rather thick, very brilliant inside, and 

 of a red cast. Caillaud says that the natives 

 of Egypt use it in preparing flax, and as spoons 

 in measuring oil, butter, and different kinds of 

 provisions. 



Division IV. — Conchifera ambigua.* 



This division contains but one family, Cha- 

 midce. 



Family 12. — Chamidce.-f 

 The Chamidse form the last family of the 

 Dimyaria : the shells are large, rough, irregular, 

 and attach themselves by one of their valves to 

 rocks, corals, &c, or even to each other in a 

 curious manner. There are three genera. 



63. Diceras. — Shell inequivalve; bosses 

 very much lengthened, distorted, 

 and turned different ways; one large 

 tooth in the largest valve. Animal 

 unknown. — 2 species fossil. 



* Les Conchiferes ambigus, Lamarck. Ambigua, from 

 ambiguus, Lat., doubtful, 

 \ Les Camacees, Lamarck. 



H 4 



