The muskrat, which is one of the most widely distributed and important of American fur-bearing animals, is really a a sort of big aquatic vole.
Lemmings
Still more mischievous, in Norway and Sweden, are the odd little rodents known as lemmings, which make their appearance from time to time literally in millions. They always seem to come down from the mountains, and when once they have begun their journey nothing will stop them. If they come to a river they swim across it; if to a house, they climb over it; if to a stack of corn or hay, they eat their way through it. Large numbers of wolves, foxes, weasels, stoats, hawks, and owls soon discover the swarm, and kill off the animals in thousands; but still the great army moves steadily on, leaving the country perfectly bare behind it, until it reaches the sea. And then those behind push on those in front, till almost the whole vast host perish in the waves.
These great migrations take place, as a rule, about once in seven years, and no one seems to know quite where the lemmings come from, or why they travel in this singular manner.
These strange little animals do not seem to know what fear is, for if a passer-by happens to meet one of them it will never turn aside, but will sit up and yelp defiantly at him, while if a dog goes up and examines it, the chances are that it will try to bite his nose!
In color the European lemming is blackish brown above and yellowish white below, while its length is about six inches.
Various kinds of rodents known as lemmings are found in North America. The Hudson Bay lemming has a thick, warm fur. Eskimo children use lemming-skins to make clothes for their dolls.
Rats
The brown rat and the black rat, of course, are only too common everywhere. They seem to have come in the first place from Asia, and have spread to almost all parts of the world. For almost every ship that sails the sea is infested with rats, some of which are nearly certain to make their way ashore at every port at which she touches.
Rats are rather formidable animals, for besides being very savage, a number of them will often combine together in order to attack a common foe. We have known a large cat, for example, to be so severely wounded by rats, that after lying in great pain for two or three days it actually died of its injuries. Rats are very bloodthirsty creatures, for if one of their own number is caught in a trap, they will tear it in pieces and devour it. They will enter fowl-houses at night, and kill the birds as they roost upon their perches, while if they can find their way into a rabbit-hutch they will even destroy the rabbits.