96 RODENTS. 
white beavers are met with. 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 40 inches, of 
which 10 are taken up by the tail. The weight of the adult animal usually varies 
from about 45 to 50 lbs., but may reach as much as 60. 
Hav Orean There has been much discussion as to whether the American 
and American beaver (C. canadensis) is entitled to rank as a distinct species, or 
Beavers. merely as a well-marked variety of the Kuropean 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 characters of the skull; that of the European beaver 
being relatively narrower in front, with the nasal bones extending somewhat 

SKELETON AND JAWS OF BEAVER, 
farther back than is the case with its transatlantic cousin. <A large series of 
specimens show, however, that these characteristics are liable to a certain amount 
of variation in the two forms. 
Distcibution ce Owing to incessant persecution for the sake of their valuable 
the European fur, both the European and the American beaver are doomed to 
Beaver. —_ extinction as wild animals at no very distant date; this fate having 
already practically overtaken the European species, which only lingers on here 
and there in small numbers. Formerly, beavers were widely spread over 
Europe; and their abundance in the British Isles is attested not only by the 
numerous remains found in the fens and cavern-deposits of England, but lke- 
wise by the number of places, such as Beaverbourne, Beverage, Beaverege, 
Bevercater, Beverley, Beverstone, and Beversbrook, which derive their names 
from these animals. According to the researches of Mr. J. E. Harting, it does not 
appear that there is any historic evidence of the existence of beavers in England ; 
but in Wales it is on record that they still lingered in Cardiganshire as late as 
the year 1188. That they occurred in the south of Scotland is proved by the 
occurrence of their remains, but there is no definite historic evidence of their 
existence; while in Ireland we have neither the testimony of their remains nor 
of documents. 
