70 CONCHOLOGY. 



hinge dissimilar, large, formed by one lamellous, arched, 

 sub-crenulated, post-cardinal tooth, articulating into a furrow 

 of the saine form; exterior, post-apicial, slightly inserted; 

 two large and rather distant muscular impressions. 



Chama Lazarus. Chama florida. 



C. damaecornis. C. limbula. 



C. gryphoides. C. aeruginosa. 



C. crenulata. C. asperella. 



C. unicornis. C, decussata. 



C. arcinella. C. albida. 



C. radians. C. ruderalis, 



C. cristella. C. croceata. 

 C. Japonica. 



C. Lazarus. Lazarus's Chama. PL 12, fig. 2. 



Species of which the summits twist from left to right ; 

 imbricated, dilated, waved foliations ; striated obsoletely ; 

 exterior white, orange, red, or yellow ; interior white. 



C. arcinella. The hedgehog Chama. 

 Species of which the summits twist from right to left; 

 the pink-coloured ones of this species are the most prized. 



3. Etheria. Four species. 



Distinguished from the Chama by the want of teeth in the 

 hinge, and being of a pearly substance. It is a rare shell, 

 only found in deep water, where it is attached to the rocks 

 by the lower valve. Its irregular form is perhaps occasioned 

 by the lower valve adapting itself to the form of the body 

 to which it is affixed. Two species are fluviatile and two 

 marine. 



Shell adhering, irregular, thick, pearly, inequivalve, ine- 

 quilateral ; summits thick, little evident; hinge toothless, 

 callous, thick, irregular; longitudinal, sub-dorsal ligament, 

 partly exterior and partly penetrating into the shell ; two ob- 

 long muscular impressions, one inferior and anterior, the 



