4:34 BEAVER nearly flat, straight, and covered for the length of 9 or 10 in. with black horny scales, and is at- tached by strong muscles to a posterior projec- Beaver. tion. The common error that the tail is the beaver's trowel is confuted by the fact that the animal always uses mud and soft earth as mor- tar ; but it serves as a pounder to pack mud and earth in constructing lodges and dams, is used in swimming as a scull, elevates or de- presses the head, turns the body, assists in div- ing, and by striking a powerful blow, the re- port of which can be heard at the distance of a half mile, it gives an alarm ; while the strong muscles enable the beaver when standing erect to use the tail as a prop. Beavers are mono- tremes, and dissection is necessary to distin- guish the sex. The female brings forth from 2 to 6 young in May, and weans them in 6 weeks. The period of gestation is from 12 to 16 weeks, and the beaver lives from 12 to 15 years. Water is the natural element of the beaver, and its movements on land are awkward and slow. For commercial purposes, besides its fur, the beaver furnishes castoreum, a secretion used in medicine as an anti-spasmodic, and its flesh is much esteemed as food by trappers and Indians. The beaver is social, pairs and brings up a family to maturity, and sometimes two or more families inhabit the same pond. The common supposition that beavers live in vil- lages or colonies is erroneous. All the inhabi- tants may assist in constructing or repairing the common dam, but each family has its own lodge and burrows, and lays in its own supply of provisions for the winter. As their work is carried on by night, little is actually known of their method except from the examination of what they effect. They only build dams when they have chosen the site of their settlements on running streams which do not afford a sufficient depth of water to be secure against freezing in winter ; and this they do by cutting down trees, invariably up stream of the place selected for their weir, so that the current may bear them down toward the site. The trees which they thus cut down with their fore teeth are often five or six inches in diam- eter. Where the current is gentle, the dam is carried horizontally across ; but where the water runs swiftly, it is built with an angle or convex curve up stream. These materials rest on the bottom, where they are mixed with mud and stones by the beavers, and still more solidly secured by the deposit of soil carried down by the stream, and by the occasional rooting of the small willow, birch, and poplar trees, which they prefer for their work, in the soil at the bottom. Their houses or lodges, seldom made to contain more than four old and six or eight young beavers, are very rudely built ; sticks, stones, mud, and all the materials used in constructing the dam, are piled horizon- tally, with no method beyond that of leaving a cavity in the centre. There is no driving in of piles, wattling of fences, and mud plastering, as described ; and when leaves or grass are in- terwoven, it is done casually, not to bind the mortar, as men apply hair for that purpose. The beaver conveys the materials between his fore paws and chin, arranges them with his Beaver Lodges and Dam. fore feet, and when a portion is placed as he wishes it, he turns about and gives it a slap with his tail. In the breeding season, and in early summer, the beavers do not live in their houses, nor in communities, but only become gregarious in the winter, and when preparing for it. They begin to build ordinarily in the latter part of August, although they sometimes fell their timber earlier in the summer; but their houses are not finished and plastered un- til late in the season, when the freezing of the mud and water as the material is laid on adds much to the security of the beavers against the wolverene or glutton, which, with the excep- tion of man, is their worst enemy. The food of the beaver consists of the bark of the aspen, willow, birch, poplar, and alder, of which it lays up in summer a stock for the winter, on the bank opposite its lodges ; but unless compelled by necessity, it avoids the resinous evergreens, such as the pine and hemlock. The beaver is easily domesticated, and be-
