86 ESSAY ON CLASSIFICATION. 



works. And after all, what docs it matter to science, 

 that thousands of species, more or less, should be de- 

 scribed and entered in our systems, if we know nothing 

 about them ? A very common defect of the works rela- 

 ting to the habits of animals has no doubt contributed to 

 detract from their value, and to turn the attention in 

 other directions : their purely anecdotic character, or the 

 circumstance that they are too frequently made the occa- 

 sion for narrating personal adventures. Nevertheless, the 

 importance of this kind of investigation can hardly be 

 overrated ; and it would be highly desk-able that natu- 

 ralists should turn their attention that way again, now 

 that Comparative Anatomy and Physiology, as well as 

 Embryology, suggest so many new topics of inquiry, 

 and the progress of Physical Geography has laid such a 

 broad foundation for researches of this kind. Then we 

 may learn with more precision, how far the species de- 

 scribed from isolated specimens are founded in nature, or 

 how far they are only a particular stage of growth of 

 other species : then we shall know, what is yet too little 

 noticed, how extensive the range of variation is among 

 animals observed in their wild state, or rather, how much 

 individuality there is in each and all living beings. So 

 marked, indeed, is this individuality in many families, 

 and that of the Turtles affords a striking example of this 

 kind, that correct descriptions of species can hardly be 

 drawn from isolated specimens, as is constantly attempted 

 to be done. I have seen hundreds of specimens of some 

 of our Chelonians, among which there were not two iden- 

 tical. And truly, the limits of this variability constitute 

 one of the most important characters of many species ; 

 and, without precise information upon this point for every 

 genus, it will never be possible to have a solid basis for 



