152 MAMMALIA. 



extremities of the upper row, and three at the external ; in the lower 

 ones it is exactly the reverse- 

 Beavers are large animals, whose life is completely aquatic ; their 

 feet and tail aid them equally in swimming. As their chief food is 

 bark, and other hard substances, their incisors are very powerful, 

 and grow as rapidly from the root, as they are worn away at the 

 point. With these teeth they cut trees of every description. 



Large glandular pouches which terminate on the prepuce pro- 

 duce a highly odorous oily substance, employed in medicine under 

 the name of Castor. The organs of generation in both sexes termi- 

 nate in the extremity of the rectum, so that there is but a single 

 external opening. 



C.^ier, Buff. VIII, xxxvi. (The Beaver.) Larger than the 

 Badger, and of all quadrupeds the most industrious in con- 

 structing a dwelling, to effect Avhich these animals act in con- 

 cert. They are found in the most solitary parts of North 

 America. 



Beavers choose water of such a depth as is not likely to be 

 frozen to the bottom, and, as far as possible, running streams, 

 in order that the wood which they cut above, may be carried 

 downwards by the current to the spot where it is to be used. 

 They keep the water at an equal height, by dams composed of 

 branches of trees, mixed with clay and stones, the strength of 

 which is annually increased, and which finally, by the progress 

 of vegetation, becomes converted into a hedge. Each hut 

 serves for two or three families, and consists of two stories ; 

 the upper is dry for the residence of the animals, and the lower 

 under water for their stores of bark, Sec. The latter alone is 

 open, and the entrance is under water, having no communica- 

 tion with the land. The huts are a kind of rude wicker-work, 

 being made of interwoven branches and twigs of trees plastered 

 with mud. There are always several burrows along the bank, 

 in which they seek for shelter when their huts are attacked. 

 They only reside in these habitations during the winter ; in the 

 summer they separate, and live solitarily. The Beaver may be 

 easily tamed, and accustomed to feed on animal matters. It is 

 of a uniform reddish brown colour, and the fur, as is well 

 known, is in great demand for hatters. It is sometimes found 

 flaxen coloured, at others black, or even white. 



Notwithstanding we have carefully compared the Beavers 

 which burrow along the banks of the Rhone, the Danube, and 

 the Weser, with those of North America, we are unable to de- 

 termine whether the former are distinct species, or are pre- 

 vented from building by the vicinity of man. 



