In the first place, let us define our animal.

What is a water-rat, and where is its place in zoological systems of the
present day? Its name in science is _Arvícola amphíbius_. This title
tells its own story.

Though popularly called a rat, the animal has no right to the name,
although, like the true rat, it is a rodent, and much resembles the rat
in size and in the length and colour of its fur. The likeness, however,
extends no further.

The rats are long-nosed and sharp-snouted animals, whereas the water-rat
has a short, blunt nose. Then, the ears of the rats are large and stand
out boldly from the head, while those of the water-rat are small, short,
and rounded. Again, the tail of the rat is long and slender, while that
of the water-rat is comparatively short. Place the two animals side by
side, and you will wonder how anyone could mistake the one for the
other.

The teeth, too, are quite different.

Instead of being white, like those of the rat, the incisor teeth are
orange-yellow, like those of the beaver. Indeed, the water-rat possesses
so many beaver-like characteristics, that it was ranked near the beaver
in the systematic lists.

Now, however, the Voles, as these creatures ought rightly to be called,
are thought to be of sufficient importance to be placed by themselves,
and separated from the true beavers.