THE FARMER AT HOME. 475 



classes is divided into a greater or less number of orders, distinguished 

 by some important, clear, and remarkable peculiarities of conforma- 

 tion and structure, which are common to *all the animals included 

 under each of them. Orders are subdivided into genera. These 

 comprehend animals that have a general external resemblance to 

 each other, a kind of family likeness. Genera are made up of species. 

 Each distinct kind of animal constitutes a species, and they are known 

 from one another by their size, color, form, and various other circum- 

 stances of external appearance. Each kind of animal, then, consti- 

 tutes a distinct species ; a number of species taken together form a 

 genus ; those genera which have important and well defined points 

 of resemblance in structure and conformation common to all, are 

 placed together in an order ; whilst upon a similar principle, but 

 more extensive in its application, these orders are marshalled into 

 separate classes. 



