CHAP. I. REMARKS ON CONCIIOLOGY. 11 



ment of porcelain on a mantelpiece. Separate the shell 

 from the animal, and much less acquaintance with the 

 natural system is to he derived from their inorganic 

 covering, than Klein obtained of his birds_, by seeing only 

 their beaks and claws." * 



(11.) The above sentiments on the insufficiency of 

 the shell, in all cases, to determine its place in the 

 natural system, we are free to confess, were held by 

 us for many years. But the results of that analysis 

 now given to the public, have materially modified, if 

 not altered, this opinion. It is needless, perhaps, to 

 repeat, that a primary regard must always be had to 

 the nature of the mollusk itself ; and that, without this 

 knowledge, there are certain forms of Testacea, of 

 which neither their natural tribes nor families can be 

 conjectured, and which, for this reason, should always 

 be kept apart. There are others, again, belonging 

 to totally different families, or even orders, which 

 are so alike in their shells, that conchologists place 

 them in juxta-position.f But yet, on the other 

 hand, there are numerous other families, where the 

 modifications in the form of the shell are just as im- 

 portant, and even more so, than those of the animal. 

 The molluscous system of Poll fully establishes this 

 proposition, even though the innumerable proofs in its 

 support, hereafter detailed, were rejected. The truth 

 appears to be, that Nature, on the whole, has diversified 

 the external aspect of these singular animals, — that is, 

 their shells, — much more than she has their soft or more 

 unsightly parts. If, therefore, she has thus bestowed 

 all her beautiful embellishment upon the habitation 

 rather than upon the inhabitant, we may at least con- 

 clude that the one is as essential to develope the plan 

 she has pursued in her own system, as is the other. 

 The diversity she has created on the shelly coverings of 

 the typical Testacea is, beyond all comparison, greater 



* Hor. Entom. p 240—244. 



f Particularly the prototypes of the Planariilar, as Vitrina, Sigarelus,, 

 Chcelinotus, &c. 



