RODENTS 
late years been made into the subject of many of the 
frightful causes of death to our species. 
The condition of the young at birth and the very re- 
markable difference in the number of them in different 
species of the Rodentia is unequalled in any other class of 
the mammalia; it will be found that the rats, mice, 
rabbits, and some others, produce from five to fourteen or 
fifteen at birth ; on the other hand, the agouti, porcupine, 
guinea-pig, the hare, and others, only one or two at a 
birth. (The hare has been known to produce three, but 
this happens rarely.) 
Some live in water and almost under water, such as 
beavers, water voles, etc. Others, where no water exists, 
of which the jerboas are a good example ; many on the 
surface of the ground, like bares ; while, probably, the 
larger number of species, like rabbits, marmots, por- 
cupines, etc., live in burrows underground. Some live in 
trees, like squirrels. Beavers by swimming and diving ; 
jerboas by hopping and jumping; hares by swiftly 
running ; rabbits, marmots, and porcupines by burrowing; 
squirrels by rapid jumping and flying from branch to 
branch — show a diversity in the modes of escaping from 
their pursuers only equalled by the variety of kinds of 
food upon which they are enabled to exist. 
The beavers, water voles, hares, rabbits, and others, live 
entirely upon vegetable substances, the porcupines and a 
few others upon a mixed diet of animal and vegetable 
products, but none can so completely give up the vege- 
tarian diet as our common rat, who can and does so accom- 
modate his stomach to surrounding circumstances, that 
he can live entirely upon flesh, fat, cheese, horns, hoofs, 
glue, old boots, soap, and, if nothing else can be obtained, 
Holloway’s ointment. 
The class Pvodentia, or gnawing animals, comprises a 
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