Photo by A. S. Rudland & Sons.
OCTODONT.
The octodonts, so called because they have four molar teeth on each side of the jaw, are a group of rodents found mainly in South America.
The Water-rat belongs to the vole group. It is one of the most commonly seen of all our English mammals—probably, except the rabbit, the most familiar. Although not entirely nocturnal, it prefers the darkness of twilight; but whenever the visitor to the waterside keeps still, the water-rats will allow him to watch them. The writer has had rather an extensive acquaintance with these cousins of the beavers, and, while watching them, has never ceased to be struck with their close resemblance to those creatures. At Holkham Lake, in Norfolk, he noticed a willow-bush, in which a number of twigs had been gnawed off; and then saw the missing sticks lying neatly peeled, just like "beaver-wood," in the water below. Waiting quietly, he noticed a water-rat climb into the bush, gnaw off a willow twig, descend with it to the edge of the water, and there, sitting on some crossed boughs, peel and eat the bark, just as a beaver does. By the Thames a sound is often heard in the round reeds as of something tearing or biting them; it is made by the water-rats getting their supper. The rat cuts off three or four sedges and makes a rough platform. It then cuts down a piece of one of the large round reeds full of pith, and, holding it in its hands, seizes the bark with its teeth, and shreds it up the stem, peeling it from end to end. This exposes the white pith, which the rat then eats. Water-rats have been seen to swim out and pick up acacia blossoms floating on the water. When swimming under water, each hair is tipped by a little bubble, which makes the rat look like quicksilver. When it comes out, the rat shakes itself with a kind of shiver, throwing all the water off its coat. Though so good a swimmer, its feet are not webbed. It is found from Scotland to the Bering Sea, but not in Ireland.
In the Far North the Lemming takes the place of the voles. It is a very small, short-tailed creature, like a diminutive prairie-dog. Like the voles, lemmings have seasons of immoderate increase. They then migrate in enormous flocks, and are said never to stop till they reach the sea, into which they plunge. It is believed that they are following an inherited instinct, and that where there is now sea there once was land, over which they passed onwards.
Photo by L. Midland, F.Z.S.] [North Finchley.
COYPU.
This is a large aquatic rodent, found on the South American rivers. Its fur, called "nutria," forms a valuable export from Argentina.