. Mammals of other lands;. Mammals. CHAPTER IX. THE RODENTS, OR GNAWING 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 ot
. Mammals of other lands;. Mammals. CHAPTER IX. THE RODENTS, OR GNAWING 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, a water-Hving 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 ; 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
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