1268 THE RODENTS 



attaches to beavers which is not vouchsafed to other members of the order to which 

 they belong. As is so frequently the case in analogous instances, the constructive 

 abilities and engineering capacities of these animals marvelous as they undoubt- 

 edly are have, however, been greatly exaggerated in popular estimation, and the 

 creatures have been credited with performing tasks of which they are utterly 

 incapable. 



Beavers, of which there are two species or varieties, one confined to Northern 

 and Eastern Europe and parts of Western and Northern Asia, and the other to 

 North America, are the only existing representatives of the family to which they 

 belong, and constitute the genus Castor. The family is characterized by the 

 massive form of the skull, in which there are no postorbital processes defining the 

 hinder border of the eye sockets, and the angle of the lower jaw is rounded off. 

 There is but one pair of premolars in each jaw, and the cheek-teeth have no roots, 

 a perfectly flat grinding surface, and re-entering folds of enamel. The two series of 

 cheek-teeth converge toward the front of the jaws, and the premolar in each jaw is 

 larger than either of the molars. 



As a genus, beavers are characterized by their stout and heavy bodily con- 

 formation, this being most marked in the hind-quarters. The head is large and 

 rounded, with short ears, and the tail is of moderate length, much flattened, and 

 covered with a naked, scaly skin. The limbs are short, with five sharp-clawed toes 

 on both the fore and hind-feet; * all the toes of the hind-feet being connected by a 

 web extending to the roots of the claws. The portion of the muzzle surrounding 

 the nostrils is naked, as are the soles of the feet, while the ears are scaly. Both the 

 ears and the nostrils are capable of being closed. The fur is peculiarly thick and 

 soft, its general color being reddish brown above, and grayer beneath. There is, 

 however, some amount of individual variation in this respect, individuals from 

 northern regions inclining to be darker in coloration than those from the southern 

 districts of the habitat of these animals. Pied or white beavers are met with 

 occasionally. Each molar tooth has three folds of enamel on one side, and one on 

 the other; the three folds occurring on the outer side in those of the upper jaw, and 

 on the inner side in the lower teeth. In size, the beaver is the largest of all the 

 Old-World Rodents, its total length being about forty inches, of which ten are 

 taken up by the tail. The weight of the adult animal usually varies from about 

 forty-five to fifty pounds, but may reach as much as sixty. 



There has been much discussion as to whether the American beaver 



( C. canadensis} is entitled to rank as a distinct species, or merely as a 

 American r 



Beavers well-marked variety of the European Castor fiber; and there is still a 

 difference of opinion among zoologists on this point. That the two 

 are very closely allied is admitted on all sides; and although the matter is not of 

 very much importance one way or the other, it is, on the whole, convenient to adopt 

 the view of their specific duality. The main difference between the two forms is to 

 be found in the characteristics of the skull; that of the European beaver being 

 relatively narrower in front, with the nasal bones extending somewhat farther back 

 than is the case with its transatlantic cousin. A large series of specimens show, 



* There is an additional claw on the second toe of the hind-foot, probably employed in dressing the fur. 



