The Squirrels are pretty little animals, distinguished by their graceful forms and bushy tails. The Common Squirrel lives in tree-tops and feeds upon fruit and nuts. During the fine summer nights the voices of the Squirrels may be heard, as they chase each other in the tops of the trees. They appear to dislike the heat of the sun, and remain during the day in their nests, coming out in the evening to play and to feed. The nest is warm, neat and impervious to rain; it is generally placed in the fork of a tree. They construct it by interlacing twigs with moss, pressing and treading on their work to make it firm and capacious, that their little ones may repose in safety. The only opening to this nest is at the top, just sufficiently wide to allow the Squirrel to pass in and out; above the aperture is a kind of conical roof, which completely shelters it, and allows no rain to enter the nest. At the commencement of winter the coat of the Squirrel is renewed, the hair being redder than that which falls off. They comb and smooth themselves with their paws and teeth, and are very neat. GREY SQUIRRELS. “The Grey Squirrels of North America,” says Audubon, “migrate in prodigious numbers, crossing large rivers by swimming with their tails extended on the water, and traverse immense tracts of country where food is most abundant. During these migrations they are destroyed in vast numbers. Their flesh is very white and delicate, and affords excellent eating when the animal is young.” THE FLYING SQUIRRELS. The Flying Squirrels are so called from having the skin of the sides spread out between the fore and hind legs, so as to constitute a sort of parachute, whereby there are enabled to sail through the air to some distance, and thus take prodigious leaps from tree to tree. The Flying Squirrels are gregarious, traveling from one tree to another in companies of ten or twelve together. They will fly from sixty to eighty yards from one tree to another. They cannot rise in their flight, nor keep in a horizontal line, but descend gradually, so that in proportion to the distance the tree they intend to fly to is from them, so much the higher they mount on the tree they fly from; that they may reach some part of the tree, even the lowest part, rather than fall to the ground, which exposes them to peril. But having once recovered the trunk of a tree, no animal seems nimble enough to take them. Their food is that of other Squirrels, including nuts, acorns, pine-seeds, berries, &c. MARMOTS AND PRAIRIE DOGS. [Illustration: PRAIRIE DOGS.] Between the lively, graceful, well-proportioned Squirrels and the Marmots, with their squat bodies and sluggish movements, there is a great difference. Yet, notwithstanding this, the Marmots are allied to the Squirrel.