The beaver may be said to occupy amongst mammals the place that ants do amongst insects. Wood says of him: “Of the Social Mammalia, he takes the first rank, and is the best possible type of that group. There are other social animals, such as the various marmots and others; but these creatures live independently of each other, and are only drawn together by the attraction of some favourable locality. The beavers, on the other hand, are not only social by dwelling near each other, but by joining in a work which is intended for the benefit of the community.” As everyone knows, the beaver is an aquatic animal, as is sufficiently indicated by his appearance. He has a dense, woolly coat, which, as in the case of the otter and the still more water-loving seals, is protected by an outer covering of long, smooth hairs, which are of a reddish brown colour. The toes of the hind feet are webbed, whilst the tail is broadened out into the shape of a paddle, the blade of which, however, lies flat on the water, so that it is not used by the animal as we would use a scull or a paddle, but with an upward and downward motion. When the beaver moves his tail laterally—that is to say from side to side—as he is very well able to do, it cuts the water, after the manner and with the same effect that a scull does when worked by a seaman at the stem of the boat, instead of in the rowlocks as we use it. [Illustration: OTTER AND SALMON.] This tail of the beaver is a very wonderful organ, and by far the most conspicuous feature about the animal. The late Mr. Morgan, who made a study of beavers and their habitations, says of it: “It is nearly flat, and covered with horny scales of a lustrous black. These scales, which are such in appearance only, cover every portion of the surface, both above and underneath. Its principal uses are to elevate or depress the head, while swimming, to turn the body and vary its direction, and to assist the animal in diving. It is also used to give a signal of alarm to its mates. When alarmed in his pond, particularly at night, he immediately dives, in doing which the posterior part of his body is thrown out of water, and as he descends head foremost, the tail is brought down upon the surface of the water, with a heavy stroke, and deep below it with a plunge. The violence of the blow is shown by the spray, which is thrown up two or three feet high.”