CHAPTER IX. 



THE RODENTS, OR GNAWING ANIMALS. 



T 



HE Rodents, or Gnawing Mammals, have all 

 the same general type of teeth, from which 

 the order receives its distinctive name. There 

 are a very large number of families and of genera among 

 the rodents, more than in any other order of mammals. 

 All the rodents possess a pair of long chisel-shaped in- 

 cisor teeth in each jaw. The ends of these teeth are 

 worn into a sharp edge which cuts like a steel tool. In 

 most rodents these are the only teeth in that part of the 

 jaw, a wide gap intervening between them and the other 

 teeth. The hares, rabbits, and calling-hares have a 

 minute pair of teeth set just behind the large pair in 

 the upper jaw. The grinding-teeth are set far back, 

 and are never more than six in number, these being 

 sometimes reduced to four. Rodents generally have 

 five toes on the fore feet ; in the hind feet there are in 

 some cases only four, or even three. None of the 

 species are of great size ; the largest, the CAPYBARA, \ 

 water-living animal of South America, is about the 

 dimensions of a small pig. But the number of species 

 of small rodents is prodigious, and their fecundity so 

 great that they constantly increase in favourable seasons 

 until they become a 

 plague. Voles, lem- 

 m i n g s , field-mice, 



and rabbits are constant sources of loss to agriculture in their 

 seasons of extraordinary increase. Most rodents feed on 

 vegetables, though rats and mice have developed carniv- 

 orous tastes. No rodents have canine teeth. 



THE SQUIRRELS. 



Those of the order of Gnawing Animals which have 

 only two incisors in each jaw, and no rudimentary teeth like 

 those possessed by the hares, are called " Simple-toothed 

 Rodents." Of these the family usually placed first in order 

 is that of the SQUIRRELS and their allies. The True Squirrels 

 and Marmots have five molar teeth on each side of the 

 upper jaw. 



Squirrels are found in nearly every temperate part of 

 the globe, from Norway to Japan, and in very great numbers 

 in India and the tropics. Everywhere they are favourites ; 



146 



Photo by W. P. Dando] 



CAPYBARA 



TAii t the largest of the rodents, is found by the rivers of 

 South America 



By fermission of Professor Bumpus, New T 



FLYING-SQJJIRREL 



One of the small species of the group 



