The general form is stout and heavy, especially in the hinder parts; the tail is of moderate length, broad, flattened, and covered with a scaly skin; the feet are all five-toed, the fore pair considerably smaller than the hinder, but all well furnished with claws, and the hinder pair fully webbed to the extremities of the toes. The wrist has a large ossicle, in addition to those usually composing that part of the body. The eyes are small, have the pupil vertical, and are furnished with a nictitating membrane; the ears are small and short, and their antitragus can be so applied to the head as almost entirely to close the auditory aperture; and the nostrils are also so arranged as to be capable of closing. [Illustration: BEAVER.] The Beaver is usually about two feet and a half long, and is, therefore, one of the largest of the Rodentia, except the Capybara. The tail, which is flattened above and below, and of an elongated oval form, measures about ten inches. The muffle is naked; the ears scaly; the soles of all the feet are naked, and their upper surfaces clothed with hairs; and the second toe of the hind feet is usually furnished with a double claw, the additional one being placed beneath the other. The general colour of the fur is reddish-brown on the upper surface, lighter and greyish below. The colour varies a little in different individuals, and appears to become darker, or even blackish, in northern localities. White or pied individuals are not uncommon. The Beaver appears to increase in size for some years after it has attained maturity. Mr. Allen says that in America “two-year-old Beavers generally weigh about thirty-five to forty pounds, while very old ones occasionally attain a weight of upwards of sixty.” The size of the skull seems to increase throughout life; the thickness and density of the bones also increase, and the ridges for the attachment of the muscles become stronger in old individuals.