Fig. 51.-Shrew Mouse.

guished from it by its long snout, which it uses in grubbing the earth in search of worms and insects. The Water Shrew dives and swims with great ce

lerity, and lives on the grubs of aquatic insects, which it digs out of the mud with its snout.

111. The Hedgehog, Fig. 52, is the only animal in En

Fig. 52.Hedgehog.

gland that has its skin armed with spikes. These are its means of defense. When attacked, it rolls itself up, and such is the arrangement of these spikes

that the tightening of the skin makes them all stand out. A dog or a fox will not touch it then. Its food is insects, snails, frogs, snakes, roots, etc. Dr. Buckland put a hedgehog in a box with a snake. It gave the snake several quick bites in succession, rolling itself up after each bite. When the snake was sufficiently disabled, the hedgehog ate it leisurely as one would eat a radish, beginning at the tail. In winter this animal lies torpid in a hole lined with grass and moss, and if discovered looks like a ball of leaves, these having become fastened to its spikes as it rolled itself among them.

112. The Banxrings differ from the other families of this order in being arboreal in their habits, ascending trees with the agility of Squirrels, which animals they resemble in general appearance, but are easily distinguished from them by their sharp muzzles.

113. The order Rodentia, or Gnawing Quadrupeds, has eight families: 1. Squirrels. 2. Marmots. 3. Rats and

Mice. 4. Beavers. 5. Porcupines. 6. Guinea Pigs. 7. Chinchillas. 8. Hares. This order contains about three hundred species, and is the most generally distributed of all the orders of terrestrial Mammals. Its species are found in all quarters of the world, a few of them even in Australia. The furs of some of them are very valuable, as the Beavers, the Chinchillas, and the Gray Squirrels.

114. The grand peculiarity of this order is in their gnawing teeth. These are in front, two in each jaw, and they are peculiarly constructed. The front covering of the tooth is enamel, and its rear portion, that is, the body of the tooth, is ivory, which is by no means as hard as enamel. Observe the effect of this arrangement. As the upper and lower teeth are brought together in gnawing, the enamel does not wear away as fast as the ivory, because it is harder. The thin enamel, therefore, always presents a sharp chiseling edge above the level of the ivory. No other class of animals has this peculiarity. These teeth are used for different purposes, as, for example, by Squirrels in opening the shells of nuts, and by Rats in making holes in wood. The teeth of other Mammalia have a limit to their growth, but not so with these front teeth of the Rodents. These grow continually, but are kept always of the same length by the wear of the gnawing operation. If, therefore, one of them be lost, the one opposite will attain a great length. In Fig. 53

you see the lower jaw of a rabbit in which the two teeth are very long because the upper teeth were lost. A Rodent in such a plight is essentially disabled, and may die of starv

Fig. 53. Overgrown Teeth ation. of Rabbit.

115. The other teeth in the Rodents are situated far back, as seen in Fig. 54 (p. 70). These back teeth are of different kinds in the different families, according to the nature of their food. Thus in the Squirrels, which live on nuts, these teeth are rounded,

Animal.

116. The bushiness of the tail is the peculiar characteristic of the

Fig. 54.—Skull of Rodent Squirrel family. This, when spread out, is of some assistance in the leaping of these arboreal animals, both guiding and buoying them up. In the Flying Squirrel, Fig. 55, there is an ar

Fig. 55.-Flying Squirrel.

rangement similar to that of the Flying Lemur, § 57.

117. The American Marmot, or Woodchuck, as it is commonly called, is about the size of a rabbit. It has an underground habitation, divided into apartments, and lives on clover and

esculent vegetables. Like some of the Monkeys (§ 52), it has cheek pouches, in which it carries stores of food to its burrow.

118. The Mouse and Rat family is the most numerous of all the families of the Mammalia, and contains the smallest animals. Of the common Mouse, Cuvier says, 'it is known in all times and in all places." Of the Rats there are two principal species, the Black Rat, and the Brown or Brownish-gray. The Black Rat is called the old English Rat, which was introduced into England from France as late as the sixteenth century. This is now nearly exterminated by the Brown Rat, which is a stronger animal. This latter Rat was introduced into this

country at the time of the Revolution in the foreign ships.

119. The Jerboas are singular animals, making an aberrant genus of this family. They have long tails with

tufted ends, and long

hind legs, which en

Fig. 56.-Egyptian Jerboa.

Fig. 57.-Beaver.

able them to make enormous leaps. The Egyptian Jerboa, Fig. 56, is about the size of a large rat.

120. Of the Beaver family, the common Beaver, Fig. 57, so well known in Canada and the northern part of the United States, is the type species. It is distinguished from all the other Rodents by its flat and scaly tail. Its hind feet are webbed, and with these and its tail it is expert in swimming. Its incisor teeth are large and uncommonly hard, and with them it can divide a

common walking-stick at a bite with as clean a cut as that of a hatchet. Like the Seal (§ 101), it can close its ears and nostrils when it dives into the water. Beavers are very celebrated for the skill with which they build their dams and habitations, which they always do in companies.

121. The common Porcupine, Fig. 58 (p. 72), is found

Fig. 58.--Porcupine.

in Africa, India, Persia, Tartary, and in some parts of Europe. It is nearly the largest of the Rodents. The spikes. or quills with which it is covered constitute, like those of the Hedgehog, its means of defense. If it can not escape, it stands still, with its quills all bristling, or even runs back against its adversary. The fact that any quills that are a little loose fall off, or remain sticking to an adversary, has given rise to the mistake that the animal has the power of shooting them from its body.

122. Of the Guinea-pig family, the Capybara, Fig. 59,

Fig. 59.-Capybara.

make it look quite like a pig.

is the largest of all the Rodents. It is a native of South America, where its flesh is much prized. It is a favorite prey of the Jaguar. Its shape, and its thin and straight hair,

123. The Hares differ from the other Rodents in having more than four front sharp teeth. There are about thirty species. The Hare, which in England furnishes