120 The Beaver. 



ARTICLE XY.— On the Beaver.— Castor fiber. 



GENUS CASTOR.— Linn. 



DENTAL FORMULA. 



Incisive | ; Canine ^ — f ; Molar | — | = 20. 



" Incisors very strong. In the upper jaw their anterior surface is 

 flat and their posterior surface angular. The molars differ slightly 

 from each other in size, and have one internal and three external 

 grooves. In the lower jaw the incisors present the same appear- 

 ance as those of the upper ; but are smaller. In the molars there 

 are three grooves on the inner side, with one on the external. 



"Eyes small ; ears short and round ; five toes on each foot. On 

 the fore-feet the toes are short and close ; on the hind-feet long and 

 palmated. Tail, large, flat, and scaly. Mammae, four, pectoral '. 

 a pouch near the root of the tail, in which an unctuous matter is 

 secreted. 



" There is but one well established species known to belong to 

 this genus. 



" The generic name is derived from the Latin word Castor^ a 

 beaver. 



CASTOR FIBER.— LisN, 

 (VAR. AMERICANUS.) 



American Beaver. 



©haracters. 



Larger than the ground-hog^ {Arctomys monax ;) of a reddish- 

 brown colour, with a short downy grayish fur beneath ; tail, fiat^ 

 scaly J and oval, 



description. 



"The shape of the body bears a considerable resemblance to that 

 of the musk-rat ; it is, however, much larger, and the head is pro- 

 portionally thicker and broader. It is thick and clumsy, gradually 

 enlarging from the head to the hips, and then is somewhat abruptly 

 rounded off to the root of the tail. 



