CLASSIFICATION. 9;|_ 



tutc for knowledge, might eclipse tlic claims of tliat 

 great man. But, when analyzed, they are found to be, 

 in their general outlines, essentially the same as the 

 method proposed by him, the new one being merely a 

 new nomenclature, with changes in the arrangement 

 of the subordinate parts, and such new grouping of 

 genera, as more recent anatomical investigations have 

 rendered necessary.^ Some difference there is, also, 

 in the opinions held concerning the comparative rank 

 and value of the different sections, and the limits of 

 the division itself, some authors including among the 

 Mollusks one or more classes of animals which are 

 excluded by others, and elevating to the rank of dis- 

 tinct classes groups which, by others, are placed in the 

 subordinate position of orders and families. AVith these 

 changes and limitations, the primary subdivisions re- 

 main as proposed by M. Cuvier in 1798, the minor 

 parts having been from time to time modified by the 

 labor of himself and other authors who have treated of 

 these animals as a class. 



It is not intended, here, to give a particular account 

 of the classification of the Mollusks as at present re- 

 ceived, but it is essential to the correct understanding 

 of our subject, so far to exhibit it, as to show the 

 position which the animals described in this work 

 hold, the peculiarities which characterize them as a 

 body, and the relations which they bear to each other, 

 and to the other famihes of the same type of organi- 

 zation. No method of classification hitherto published, 



