THE CLASSIFICATION OF ANIMALS. 223 
CHAPTER XXI. 
THE CLASSIFICATION OF ANIMALS. 
Tue Kingdom of Nature is a literal Kingdom. Order 
and beauty, law and dependence, are seen everywhere. 
Amidst the great diversity of the forms of life, there is 
unity; and this suggests that there is one general plan, 
but carried ont in a variety of ways. 
Naturalists have ceased to believe that each animal or 
group is a distinct, circumscribed idea. “ Every animal 
has a something in common with all its fellows: much 
with many of them; more with a few; and, usually, so 
much with several, that it differs but little from them.” 
The object of classification is to bring together the like, 
and to separate the unlike. But how shall this be done ? 
To arrange a library in alphabetical order, or according to 
size, binding, date, or language, would be unsatisfactory. 
We must be guided by some internal character. We must 
decide whether a book is poetry or prose: if poetry, wheth- 
er dramatic, epic, lyric, or satiric; if prose, whether his- 
tory, philosophy, theology, philology, science, fiction, or 
essay. The more we subdivide these groups, the more 
difficult the analysis. 
A classification of animals founded on external resem- 
blances, as size, color, or adaptation to similar habits of 
life, would be worthless. It would bring together Fish- 
es and Whales, Birds and Bats, Worms and Eels. Nor 
should it be based on any one character, as the quality 
of the blood, structure of the heart, development of the 
brain, embryo-life, etc.; for no character is of equal value 
in every tribe. A natural classification must rest on those 
