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. fiber, Buff. VII, xxxvi. (The Beaver.) Larger than the 
Badger, and of all quadrupeds the most industrious in con- 
structing a dwelling, to effect which these animals act in con- 
cert. They are found in the most solitary parts of N orth 
America. 
Beavers choose water of such a depth as is not likely to be 
frozen to the bottom, and, as far as possible, running streamsy 
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, &c. 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 5 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. i 
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 ded 
termine whether the former are distinct species, or are preg 
vented from building by the vicinity of man. 
