The genus of Beavers (Castor) is apparently represented by a single living species. By some authorities the American form is considered a distinct species and is given the technical name Castor canadensis, while the European form is called Castor fiber. In external characteristics the two resemble each other very closely, and it is in the study of the structure of the skeleton that the differences appear. However, though there is this diversity of opinion, it is sufficient for the reader to look upon the two forms as merely geographical races of the same species, and that the Beaver is a native of the greater part of the northern hemisphere. Though its home covered this extensive area, it has disappeared from the larger number of localities that it once frequented. Speaking of its range as a whole, it may now be considered rare except in certain isolated localities. This extermination is due to the advance of civilization upon its natural haunts, and the commercial zeal that has stimulated the hunter to greater efforts to effect its capture. Within recent years the Beaver was common in some of the Gulf States. In 1876 it was reported as abundant in Virginia. It is evident from an examination of the numerous writings regarding its distribution that the Beaver formerly existed in great numbers not only in the Atlantic States, but also to the westward as far as the Pacific coast.

The Beaver is a member of that large order of gnawing mammals called the Rodentia, from the Latin word meaning to gnaw. In this order are classed all those animals that have those peculiar long incisor teeth which are constantly renewed by growth from the roots and as constantly worn to a chisel edge, at the outer end, by gnawing. Such animals are squirrels, the gophers, the mice, the rats, the muskrats, the porcupines, the hares and the rabbits.

The habits of the Beaver are very interesting. Several years are required before its growth is fully attained, and it will increase in size after the teeth are fully mature. "Two-year-old Beavers generally weigh about thirty-five to forty pounds, while very old ones occasionally attain a weight of upwards of sixty. Morgan records the capture of one which weighed sixty-three pounds. The increase in the size of the skull seems to continue nearly through life; in old age the skull not only acquires larger dimensions, but the weight is relatively greater in consequence of the increased thickness and density of the bones. The ridges for the attachment of muscles also become more strongly developed in old age."

The general color of the back of the Beaver is a reddish brown. The shade varies both with the seasons and with the geographical location. Those found farther to the northward are usually darker. Albinos, either pure white, nearly white or with white blotches, have been observed.

"The fur consists of an exceedingly thick, flaky, woolly coat of silky softness and a thin, long outer coat composed of strong, stiff, shining hair, short on the head and rear part of the back and over two inches long on the rest of the body." The tail, which is rounded at the base, much flattened and very broad, bears horny, dark-colored scales.

The fore legs are short and the feet are unwebbed. The hind legs are much stronger, the feet are fully webbed and they, alone, are used, with the aid of the tail, to propel the Beaver through the water. In the water it is graceful in its motions, but on the land, like nearly all animals that are fitted for a partially aquatic life, it is clumsy and awkward and its motions are neither rapid nor uniform.

Usually it is only in those districts that are remote from the habitations of man that the Beaver lives in colonies, consisting of several families, and builds its "lodges." Nearer civilization it lives in burrows or tunnels. In the building of their homes, as well as in the storing of a supply of food, the female is the most active and is the practical builder, while the male assists.