A peculiar formation of the incisors, or front teeth, groups a number of smaller animals together under the name of Rodentia, from the Latin word _rodens_, which signifies gnawing. These teeth act as files, so that the food on which their owners principally live is reduced by friction to a state which fits it for digestion. As the edges of these teeth become worn by constant use, they incessantly grow from the root. If one be broken, that opposite to it, in the other jaw, being deprived of its habitual wear and tear, grows so fast that it not only annoys its owner, but has caused his destruction by effectually closing the mouth. Their lower jaws can only move backwards and forwards; some exclusively eat vegetables, others eat all things, and others again prefer flesh. Some carry their food to their mouths with their paws, and climb trees; and, in many, the hinder limbs are so much longer than those in front, that they leap instead of walk. They are widely and numerously spread on the surface of the earth, and therefore bear strongly on its history; but it is not among them that we find the high intellectual development with which many other animals are gifted. Squirrels are some of the most beautiful of the Rodentia, and chiefly live in trees. The fur of some of the species is extremely beautiful and valuable; they are very active, elegant little creatures, and easily tamed, when they become very playful and affectionate. A friend of mine was deprived of her only daughter, and the lost one's pet squirrel was of course cherished and loved; the little creature used to run up the lady's arm, and seat itself on her shoulder, caress her with its head, nestle itself into her neck, and drink her tears. As long as it lived, it was never caressed by the mother without first looking in her face for the drops, which it had been accustomed to remove.