The term “_Conchology_,” in its legitimate usage, is applied to that department of Natural History which has reference to animals with testaceous covering or shells. It is not unfrequently confounded with _Crustaceology_, 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 creature 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.” Writers have not been wanting to decry this study as frivolous or inessential; most unjustly assailing the science itself, on account of the gross abuses which have now and then arisen from its exclusive and extravagant pursuit. They have reasoned much after this fashion:—that Conchology is a folly, because Rumphius was a fool. The _Conus Cedo Nulli_ has been sold for three hundred guineas; and the naturalist just mentioned gave a thousand pounds sterling for one of the first discovered specimens of the _Venus Dione_ (of Linnæus). But there have been men in all ages who have carried to an absurd, and even pernicious extreme, pursuits the most ennobling and praiseworthy. To an upright and well regulated mind, there is no portion of the works of the Creator, coming within its cognizance, which will not afford material for attentive and pleasurable investigation; and, so far from admitting the venerable error even now partially existing to the discredit of Conchology, we should not hesitate to acknowledge, that while few branches of Natural History are of more direct, _very few_ are of more adventitious importance.