iNET RORpDUC TION. 
Tue term “ Concholozy,” in its legitimate usage, is applied to 
that department of Natural History which has reference to ani- 
mals with testaceous covering or shells. It is not unfrequently 
confounded with Crustaceslogy, but the distinction is obvious 
and radical, lying not more in the composition of the animal’s 
habitation, than in the organization of the animal itself. This 
latter, in the Crustacea, is of a fibrous nature, and has articulated 
limbs ; the shell, strictly adapted to the members, covers the crea- 
ture like a coat of mail, is produced at one elaboration, is cast or 
thrown aside periodically, and, again at one elaboration, renewed ; 
it is moreover composed of the animal matter with phosphate of 
lime. In the Testacea, on the contrary, the inhabitant is of a 
simple and soft texture, without bones, and is attached to its 
domicil by a certain adhesive muscular force; this domicil, too, 
is a permanent one, and is increased, from time to time, by 
gradual additions on the part of the tenant; while the entire 
shell, which is distributed in layers, or strata, is a combination of 
carbonate of lime, with a very small portion of gelatinous matter. 
Such animals, then, with such shells, form, alone, the subject of a 
proper “ Conchology.” 
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