292 



POPULAR CONCHOLOGY. 



form with the mantle a blind canal into which the anal duct 

 opens ; on each side of the mouth are a pair of semicircular, 

 labial feelers; the foot is large, rather thick, long, and 

 oblique. The shell is somewhat like an oyster, irregular, 

 attached, inequivalve, lamellated, slightly iridescent, with 

 small bosses ; the hinge is without teeth, somewhat undu- 

 lating, and bulging, dissimilar in the two valves; the 

 ligament is visible exteriorly, but penetrates into the 

 interior. — Fluviatile. 



Etheria. Lam. — Shell and animal described in the 

 account of the family. — 3 or 4 species. 



Etheria. 



This genus is found in the rivers of Africa and Mada- 

 gascar, and is abundant in the Nile above the . Cataracts, 

 where the inhabitants collect them, for the purposes of 

 ornamenting their tombs with the shells, and feeding upon 

 the animal. They are pearly within, foliaceous on the 

 outside, large, and fix themselves by the under valve often 

 to one another, presenting the most curious distortions of 

 form. The interior of the valves is often of a vivid green 

 colour, and raised in small blisters, which are said to be 

 formed by the accidental introduction of small particles of 

 sand during the formation of the nacrous fluid. 



