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Zoological Principles of Classification, and of the Determinor 



tion of Fossils, 



It is evident that the same laws and principles which guide 

 the zoologist in the classification ot* living animals, ought 

 likewise to regulate the labours of the palaeontologist ; but the 

 mode in which beings have been preserved, which the latter 

 has to study, often entails differences in their application, of 

 which it is necessary to say a few words. 



Fossil animals are not commonly preserved in a complete 

 state, and their hard parts are almost always the only ones 

 which have come down to our times ; we are scarcely ac- 

 quainted with the mammifera but by their skeletons, and the 

 molluscs by their shells. Now, the skeletons, and more espe- 

 cially the shells, do not always contain the essential charac- 

 ters ; and the palaeontologist, restricted to such characters as 

 he can find, has to guard against forming irrational classifi- 

 cations. 



In order to avoid this stumbling-block, it is necessary to 

 make a choice among the characters presented by the hard 

 parts ; for they are far from being all equally useful in a good 

 classification, and the least apparent are often those which 

 furnish the most precise and important results. But, in order 

 to regulate ourselves in this choice, a profound study of living 

 animals is the only possible guide. The first care of one who 

 would study and classify fossils, should be to endeavour to 

 discover what are the connections which exist between the 

 forms of the solid parts and those of the most essential organs. 

 He will thus succeed in determining what are the characters 

 of the skeleton and of the shell, which are most certainly 

 connected with the principal modifications of the most im- 

 portant organs, and he will, consequently, know what those 

 are which it is necessary to place in the first rank. He will 

 soon be convinced that, among the characters which have 

 been often made use of in palaeontology, there are many to 

 which an exaggerated importance has been given, because 

 they are easily observed and conveniently employed, while a 



