Rodentia
or RODENTS, an order of mammiferous quadrupeds occupying in many respects an intermediate place between the purely carnivorous and purely herbivorous mammalia, and so forming the connecting link between them. The order embraces rats and mice, hares, rabbits, guinea pigs, and other well-known animals. These animals have two great incisor teeth in each jaw, separated from the molar by by a wide space, with which they could hardly seize a living prey or rend flesh, but could reduce them by gnawing, whence the term rodents, or gnawers, applied to this order. The characteristic of this order is that the lower jaw has no horizontal movement except from behind forward, and vice versa, convenient for the action of gnawing; the molars of the Rodentia, consequently, have flat crowns, the enameled eminences of which are always transversal, so as to be in opposition to the horizontal movements of the jaw, and to be better adapted for trituration. The hinder parts of the body of the rodents in general exceed their anterior.
Some of them enjoy a certain dexterity, using their forefeet for carrying their food to their mouth; while others again (the squirrels) climb trees with facility. Rodents are most abundant in temperate regions. In North America there are 371 species, 19 genera; 81 species, 16 genera in Europe and the N. of Asia; in Africa, 53 species, 16 genera; in India and its islands, 58 species, 10 RODGERS genera; in South America and West India Islands, 89 species, 25 genera.