PHEFACE. Vll 



" I must beg my European readers to remember that 

 this work is written in America, and more especially for 

 Americans ; and that the community to which it is par- 

 ticularly addressed has very different wants from those 

 of the reading public in Europe. There is not a class of 

 learned men here, distinct from the other cultivated 

 members of the community. On the contrary, so general 

 is the desire for knowledge, that I expect to see my book 

 read by operatives, by fishermen, by farmers, quite as 

 extensively as by the students in our Colleges or by the 

 learned professions, and it is but proper that I should 

 endeavour to make myself understood by all. 



" Of the two volumes now complete of this series, the 

 First Part contains an exposition of the general views I 

 have arrived at, thus far, in my studies of Natural His- 

 tory." (It is this First Part, entitled Essay on Classifi- 

 cation, which is here reprinted). "The Second Part 

 shows how I have attempted to apply these results to the 

 special study of Zoology, taking the order of Testudinata 

 as an example. The Third Part exemplifies the bearing 

 of Embryology upon these general questions, while it 

 contains the fullest illustration of the embryonic growth 

 of the Testudinata. " 



