Field Mice and Dormice are other kinds of small rodents, differing from the common kind of mouse; but the habits and appearance of these little quadrupeds are well-known.
The Beaver and Musk-rat, or Musquash of America, are usually classed among the rat tribe; but these animals, for many reasons, deserve to stand apart and form a group of themselves. With regard to the shrew-mice and moles, there is less reason for separating them from other mice; and we shall speak of them in this connection.
The Moles are known to be the best burrowers in the world: since they can pass under the surface of the ground as fast as a man can dig after them, or even faster. In England, the common mole is well-known—too well, in fact—for it is the very pest of the farmer; and the damage done by it to the herbage is very considerable indeed—of greater amount than that occasioned by any other wild animal.
In America, where there are several species of moles, their habits are similar; and the common American mole is very like its European congener in every respect. But there are two or three species found in North American countries very different from either; and the most singular of all is that known as the Star-nosed Mole. This creature has the cartilage of the snout extended into five or six branches, that radiate from each other, like spokes of a wheel, or the points of a star—hence the name of star-nosed mole. The use of this singular appendage is not clearly understood; and, indeed, it would appear to be an obstruction to the natural requirements of the animal. No doubt, however, it has its purpose—though that purpose be unknown to us.
The Shrew-Mice are still another kind of small ratlike quadrupeds. They are distinguished by having upon each flank, under the ordinary skin, a little band of stiff and close hairs, from which an odoriferous humour is distilled. They dig holes in the earth, which they seldom come out of until towards evening; and their food consists of insects and worms. A species that inhabits the Pyrenees, and also the mountains of Russia, are called Desmans, and differ somewhat from the ordinary shrew-mice. They are aquatic in their habits; and their burrows always enter the ground below the level of the water. The Russian species are usually termed Musk-rats; but these are not to be confounded with the musk-rats of America—which last should undoubtedly be classed with the beavers.
In India, the shrew-mice attain to the size of ordinary rats, and are there also called musk-rats, from the fact that a strong odour of musk is exhaled by them—so strong as to make the place through which the animal passes exceedingly disagreeable. The same is true of the Russian musk-rats, but for all that their skins are employed in chests containing clothing: since the musky smell is a good preservative against the moths.
In addition to the numerous rat animals above-mentioned, there are still other kinds in different parts of the world—the names of which would alone fill many pages. Hence it is that the study of this section of the mammalia is, perhaps, the most difficult of all; and a true classification of these small quadrupeds has hitherto proved a puzzle to the most expert zoologists.