RODENTIA—GNAWING QUADRUPEDS.
THE order of animals to which the well known and widely distributed Rats and Mice belong, is a very large one, including animals that are adapted, according to the genus, either for running, jumping, climbing, flying or swimming. They are armed with sharp claws, enabling them to climb trees or burrow in the earth. But the special characteristic of all the animals of this group, is that they possess only two kinds of teeth—incisors and molars. The incisors, two in number, in front of each jaw, are very remarkable. Their office is to cut, as with shears, roots and branches, and they are wonderfully constructed for this purpose. These teeth are long, stout and curved, and being covered with enamel on their front face only, they wear away more behind than in front; and by rubbing one against the other naturally form a bevelled edge. They therefore keep a hard edge that is always sharp-cutting, ready for sawing through or gnawing tough substances.
Another strange thing about these teeth is that they always keep the same length, notwithstanding their continual wear. The fact is, they have no roots, and grow from the base in the same proportion as they are worn away at the top.
Many of the Gnawing Quadrupeds have their hind limbs much larger than the front ones, so that they leap rather than walk, giving them the appearance of the Kangaroo and others belonging to the Marsupial family. The animals of the Rodent order feed mainly on seeds, fruit, leaves, grasses and occasionally on roots and bark. Some of them, however, such as the Rat, areomnivorous, and will even eat flesh.
A great number of the Rodents have their bodies covered with fine, soft and prettily-colored hair. For instance, the small Grey Squirrel and the Chinchilla both furnish furs of value; and the coats of the Beaver and the Rabbit are used in some of our manufactures.
The Rodents are not usually divided into very distinct families, as their natural characteristics are not clearly marked. In the family of Rats and Mice a large number may be grouped. These form the Mus species, from the Latin, Mus, meaning Mouse or Rat. The most of the members of this family are too well known to require more than mere mention. This family includes besides what are known as the Rats and Mice proper, the Field Rats and Mice, the Dormice, Ondatras, Musquash or Musk Rats, Lemmings, Hamster Rats and Jerboa Rats.
Grouped with the Chinchillas we find the Lagotis, the Viscacha, and the Ctenomys. Then come the Porcupine family, the family of Ground Hogs, Guinea Pigs and the Agoutis. The Beavers and the extensive Squirrel family are then followed by the Marmots and Woodchucks, the Prairie Dogs, and the large family of Hares and Rabbits.
BEAVERS.
BEAVERS.
BEAVERS.
These animals, which are celebrated all over the world for their industrious habits and their intelligence, do not possess a very pleasing appearance. The thick-set shape of the large head, small eyes, cloven upper lip which shows its powerful incisors, the long and wide tail, flattened like a spatula and covered with scales—combine to give the animal an awkwardappearance. The hind feet are larger than the fore, and are fully webbed.
The Common Beaver is an aquatic animal; the structure of its feet and tail enables it to swim with perfect facility. As these animals live principally upon the bark of trees and other hard substances, their front teeth are excessively strong, and by their assistance they are enabled to cut down trees of considerable size, to be used in the construction of the curious edifices for the erection of which they have been long celebrated. Their mode of building, as adopted by the Beaver of America, is described by Hearne with great exactness.
“The situation chosen is various where the Beavers are numerous. They tenant lakes, rivers and creeks, especially the two latter for the sake of the current, of which they avail themselves in the transportation of materials. They also choose such parts as have a depth of water beyond the freezing power to congeal at the bottom. In small rivers or creeks in which the water is liable to be drained off when the back supplies are dried up by the frost, they are led by instinct to makea dam quite across the river, at a convenient distance from their houses, thus artificially procuring a deep body of water in which to build.
“The dam varies in shape; where the current is gentle it is carried out straight, but where rapid it is bowed, presenting a convexity to the current. The materials used are drift wood, green willows, birch and poplar, if they can be secured, and also mud and stones. These are intermixed without order, the only aim being to carry out the work with a regular sweep, and to make the whole of equal strength.
“Old dams by frequent repairing become a solid bank, capable of resisting a great force of water and ice; and as the willows, poplars and birches take root and shoot up, they form by degrees a sort of thick hedgerow, often of considerable height. Of the same materials the houses themselves are built, and in size proportionate to the number of their respective inhabitants, which seldom exceeds four old and six or eight young ones. The houses, however, are ruder in structure than the dam, the only aim being to have a dry place to lie upon, and perhaps feed in.
“When the houses are large it often happens that they are divided by partitions into two or three, or even more compartments, which have in general no communication except by water; such may be called double or treble houses rather than houses divided. Each compartment is inhabited by its ownpossessors, who know their own door, and have no connection with their neighbors, more than a friendly intercourse and joining with them in the necessary labor of building.
“So far are the Beavers from driving stakes, as some have said, into the ground when building, that they lay most of the wood crosswise, and nearly horizontal, without any order than that of leaving a cavity in the middle, and when any unnecessary branches project they cut them off with their chisel-like teeth and throw them in among the rest to prevent the mud from falling in; with this is mixed mud and stones, and the whole compacted together. The bank affords them the mud, or the bottom of the creek, and they carry it, as well as the stones, under their throat, by the aid of their fore-paws; the wood they drag along with their teeth.
“They always work during the night, and have been known during a single night to have accumulated as much mud as amounted to some thousands of their little handfuls. Every fall they cover the outsides of their houses with fresh mud, and as late in the autumn as possible, even when the frost has set in, as by this means it soon becomes frozen as hard as a stone, and prevents their most formidable enemy, the Wolverine, or Glutton, from disturbing them during the winter. In laying on this coat of mud, they do not make use of their broad flat tails, as has been asserted—a mistake which has arisen from their habit of giving a flap with the tail when plunging from the outside of the house into the water, and when they are startled, as well as at other times. The houses, when completed, are dome-shaped, with walls several feet thick.”