CASTOR, the beaver, in natural his tory, a genus of Mammalia, of the or der Glires. Generic character : upper fore-teeth truncated, and hollowed in a transverse angle ; lower transverse at the top ; four grinders in each jaw ; tail long, scaly, and depressed ; clavicles per fect. There are two species, of which the most worthy of notice is C. fiber. The colour of the beaver is generally of a deep Chesnut; sometimes it has been seen entirely, white ; less rarely completely black ; it is about three feet long in the body ; its tail is the length of one foot, and by its peculiarity distinguishes this animal from every other quadruped ; it is of an oval form, and flat, with a slight convexity towards the base, desti tute of hair, and completely covered with scaly divisions. The beaver was known to the ancients fur its possession of that sebacious matter called castor, secreted by two large glands near its genitals and anus, and of which each animal has about two ounces ; but they appear to have been unacquainted with its habits and econoniy ; with that mental contrivance and practical dexterity, which, in its na tural state, so strikingly, distinguish it. Beavers are found in the most northern latitudes of Europe and Asia, but are most abundant in North America. In the months of June and July they assemble in large companies, to the number of two hundred, on the banks of some water, and proceed to the formation of their esta blishment. If the water be subject to risings and fillings, they erect a dam, to preserve it at a constant level ; where this level is naturally preserved, this la bour is superseded. The length of this dam is occasionally eight feet. In the preparation of it, they begin with felling some very high, but not extremely thick, tree on the border of the river, which can be made to fall into the water ; and in a short time this is effected, by the united operation of many, with their fore-teeth, the branches being afterwards cleared by the same process. A multitude of smaller trees are found necessary to complete the fabric, and many of these are dragged from some distance by land, and formed into stakes, the fixing of which is a work of extreme difficulty and perseverance, some of the beavers with their teeth rais ing their large ends against the cross beam, while others at the bottom dig with their fore-feet the holes in which the points are to be sunk. A series of
these stakes, in several rows, is establish ed from one bank of the river to the other, in connection with the cross-tree, and the intervals between them are filled up by vast quantities of earth, brought from a distance, and plashed with mate rials adapted to give it tenacity, anti pre vent its being carried off. The bank is formed at the bottom, of about the width of twelve feet, diminishing as it approach es the surface of the water to two or three ; being thus judiciously constructed to resist its weight and efforts by the in clined plane instead of perpendicular op position. These preparations of such hit mense magnitude and toil being complet. ed, they proceed to the construction of their mansions, which are raised on piles near the margin of the stream or lake, and have one opening from the land, and another by which they have instant ac cess to the water. These buildings are usually of an orbicular form, in general about the diameter of ten feet, and com prehending frequently several stories. The foundation walls are nearly two feet' in thickness, resting upon planks or stakes, which constitute also their floors. In the houses of one story only, the walls, which in all cases are plastered with ex treme neatness, both externally and with in, after rising about two feet perpendi cularly, approach each other, so as at length to constitute, in closing, a species of dome. In the application of the mor tar to their habitations, the tails as well as feet of the beavers are of essential ser vice. Stone, wood, and a sandy kind of earth, arc employed in their structures, which by their compactness and strength completely preclude injury from winds and rain. The alder, poplar, and willow, are the principal trees which they employ; and they always begin their operations on the trunk, at nearly two feet above the ground ; nor do they ever desist from the process till its fall is completed. They sit instead of standing at this labour, and while reducing the tree to the ground derive a pleasure at once from the success of their toils, and from the gratification of their palate and appetite by the bark, which is a favourite species of food to them, as well as the young and tender parts of the wood itself.