It passes the winter in its house, which it then furnishes with a soft bed of leaves, grasses, and sedges, and, according to Audubon, ventilates by covering the middle of the dome only with a layer of similar materials, through which the air can pass. Of the propagation of the Musquash very little seems to be known with certainty. They pair in April and May, and the female produces from three to six young at a birth; but whether this takes place once or several times in the course of the summer is a matter of doubt. They are captured in fall-traps baited with apples, or by traps set at the mouth of their burrows. The Indians sometimes spear them in their houses. [Illustration: MUSQUASH.] The LEMMING (_Myodes lemmus_) is one of the most remarkable of the Muridæ, on account of the great migrations which it performs, apparently with no special object. In Norway, where it is best known, they make their appearance in the cultivated districts in such enormous numbers, and so suddenly, that the peasants have always believed them to fall from the clouds. The Lemming is a Vole-like animal, about six inches long, of which the tail makes up about half an inch. It varies considerably in colour, but is usually brownish-yellow, with dark spots above, and with a yellow streak enclosing the eye on each side of the face; the under surface is yellowish. The ears are very short, scarcely projecting beyond the fur; the eyes are small, black, and bead-like; the soles of the feet are hairy, and the claws of the fore feet much stronger than those on the hinder extremities. The Norwegian Lemmings live and breed among the peat mosses of the mountains. They are lively and active little creatures both by day and night, and feed upon the scanty vegetation of their Alpine home--grasses, lichens, the catkins of the dwarf birch, and roots. They are active even through the winter, when they make passages for themselves under the thick covering of snow which then veils the whole country, and thus are enabled to go in search of their ordinary food. They also make their way up to the surface, upon which they may occasionally be seen running, even in the depth of winter. They breed in their burrows and under stones, and must be very prolific, seeing that every predaceous animal in the country destroys and devours them. The Lemming is, in one sense, an exceedingly timid little creature, the slightest disturbance of its quietude, or even the passing over-head of a cloud, being sufficient to alarm it; but when attacked it displays the most dauntless courage, standing on the defensive against both men and animals, and biting very sharply at anything that comes within its reach. From time to time, from some unexplained cause, the Lemmings start in vast swarms from their mountain fastnesses, and make their way in a straight line in some definite direction. Nothing seems to turn them from their course; they go straight on, over hill and dale, and, although said at other