PREFACE. 



The publication of Cuvier's Animal Kingdom established an 

 epoch in the science of zoology. This eminent scholar brought 

 to his subject the critical and reflective powers of a great intellect, 

 and the varied and profound acquirements of a laborious life. 

 Having possessed himself of the results of antecedent as well as 

 contemporary investigations, and extended his researches with 

 more or less exactness, over the entire animal kingdom, he was 

 enabled to construct, upon the "System of Nature," that remark- 

 able system for the classification of animals, which now forms the 

 basis of zoological science.^ 



This system of classification is founded exclusively upon the 

 anatomical structure of animals, whence comparative anatomy is 

 the source of its materials. It not only rejects the habits and 

 properties of animals as immaterial and transient, but it also 

 leaves out of consideration their mental endowments, which, how- 

 ever important in other respects, were incapable of affording a 

 basis of classification. 



Under its clear and definite discriminations all the species of 

 each of the four great branches of the animal kingdom are seen 

 in intelligible and harmonious relations, notwithstanding their 

 striking diversities of form. Unity of type runs through the 

 structural organization of all the individuals comprised in each 

 of these branches. The grandeur of this fourfold plan of creation 

 is not more impressive than the wonderful adaptation of the sur- 

 rounding elements to the condition and wants of the multitude 

 of animal organisms which God has made. 



It is not, however, the whole of the science of zoology to 



1 Agassiz dates the new period from 1812, "when Cuvier laid before the 

 Academy of Sciences in Paris the results of his investigations * * * which 

 had satisfied him that all animals were constructed upon four different 

 plans." — Natural History United States, i. 193, The " Regne Animal" did 

 not appear, however, until 1816. 



(V) 



