The _Squirrels_, properly so called, are not only tree-climbers, but, as every one knows, dwell habitually upon trees, and there make their nests and their home. And perfectly at home they are among the highest branches; for under no circumstances do they ever miss their footing, or are they in the slightest danger of falling. In fact, they can not only run with the greatest agility along the branches, but equally well with their backs downward; and can spring from branch to branch, and also from tree to tree, over wide intervals of many yards. They can also leap down from the tops of the tallest trees to the earth--a feat often witnessed by squirrel-hunters--and do so without the appearance of having received the slightest injury; for, without pausing a moment on the ground, they continue their flight towards some other tree, where they expect to find better shelter from the short gun or rifle of their human enemy. The squirrel builds a nest in the tree, similar to that of some birds; but they have also in the same tree a more secure retreat in case of being pursued. This is a hole in the trunk or one of the larger limbs-- some natural excavation caused by the decaying of a branch--in short, what is termed a "knot hole," which is common in many kinds of timber. In this hole the squirrel usually lays up its store of winter food, consisting of nuts, beech-mast, etcetera; and here it takes refuge when hunted, finding the tree-cave a safe asylum. Unless decoyed out again, or, which often happens, _frightened_ out again, by rubbing the trunk with a piece of stick, the squirrel must escape scot-free nine times out of ten, since no hunter would think of felling a huge tree to procure so insignificant a reward as the carcass of a squirrel; and without felling the tree, and splitting it up, too, the creature could not be reached. Various devices, however, are practised to decoy it forth; and these, unfortunately for the little refugee, too often succeed. The squirrels are the life of the American woods--indeed, a journey through these great forests would often be very monotonous were it not enlivened by the presence and gambols of these beautiful creatures; and in the depth of winter, when the squirrels keep within their dark tree-caves, the solitude of the forest seems redoubled. But even during frost and snow, when the weather is fine and the sun shining brightly, a few will be seen venturing forth, as if to take an airing. A great many species exist in the forests of North America; sometimes only one, and sometimes several, occupy the same district. They are of different colours and sizes--some as small as the common squirrel of England, while several species are three or four times as large. Some are grey, others brown grey, several species of a fox red, and those esteemed the most beautiful are of a uniform jet black. Several new species have lately been found in the forests of Oregon and California.