66 ESSAY ON CLASSIFICATION 



acknowledged as peers by their fellow investigators, the anatomists 

 and physiologists, or the systematic zoologists. And yet, without a 

 thorough knowledge of the habits of animals, it will never be possi- 

 ble to ascertain with any degree of precision the true limits of all 

 those species which descriptive zoologists have of late admitted with 

 so much confidence into their works. And after all, what does it mat- 

 ter 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 relating 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 occasion for nar- 

 rating personal adventures. Nevertheless, the importance of this kind 

 of investigation can hardly be overrated; and it would be highly 

 desirable that naturalists should turn again their attention that way, 

 now that Comparative Anatomy and Physiology, as well as Embry- 

 ology, may suggest so many new topics of inquiry and the progress 

 of Physical Geography has laid such a broad foundation for re- 

 searches of this kind. Then we may learn with more precision how 

 far the species described from isolated specimens are founded in na- 

 ture, or how far they may be only a particular stage of gro^vth of 

 other species; then we shall know what is yet too little noticed, how 

 extensive the range of variations 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 fami- 

 lies, — and that of 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 hun- 

 dreds of specimens of some of our Chelonians, among which there 

 were not two identical. And truly the limits of this variability con- 

 stitutes 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 the distinction of species. 

 Some of the most perplexing questions in Zoology and Palaeontology 

 might long ago have been settled had we had more precise informa- 

 tion upon this point, and were it better known how imequal in this 

 respect different groups of the animal kingdom are when compared 

 with one another. While the individuals of some species seem all 



