SPECIES AND BREEDS. 137 
From a comparison of a number of well-known 
Species belonging to a natural Genus, it is not 
difficult to ascertain what are essentially specific 
characters. There is hardly among Mammalia a 
more natural Genus than that which includes the 
Rabbits and Hares, or that to which the Rats and 
Mice are referred. Let us see. how the different 
Species differ from one another. Though we 
give two names in the vernacular to the Genus 
Hare, both Hares and Rabbits agree in all the 
structural peculiarities constituting a Genus; 
but the different Species are distinguished by 
their absolute size when full-grown, — by the na- 
ture and color of their fur,—by the size and 
form of the ear, —by the relative length of their 
legs and tail, — by the more or less slender build 
of their whole body, —by their habits, some liv- 
ing in open grounds, others among the bushes, 
others in swamps, others burrowing under the 
earth,—by the number of young they bring 
forth, —by their different seasons of breeding, — 
and by still minor differences, such as the perma- 
nent color of the hair throughout the year in 
some, while in others it turns white in winter. 
The Rats and Mice differ in a similar way: there 
being large and small Species, — some gray, some 
brown, others rust-colored,—some with soft, 
others with coarse hair; they differ also in the 
length of the tail, and in having it more or less 
