RODENTIA. 99 



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. 



They have large glandular pouches which produce a highly odorous oily 

 substance, employed in medicine under the name of Castor- 



C. Jiber, Buff. (The Beaver.) Larger than the Badger, and of all quad- 

 rupeds the most industrious in constructing a dwelling, to effect wliich these 

 animals act in concert. 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 can-ied downwards by the cuiTent to tlie 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 tliree 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 communication with the 

 land. The huts are a kind of rude wicker-work, being made of interwoven 

 branches and twigs of trees plastered with inud. 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 sohtary. 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 otliers black, or even white. 



MropoTAMUs, Commer. 

 The Couias resemble the Beaver in size, in their four nearly similarly com- 

 posed molars, in their powerful yellow-tinted incisors, and in their five-toed 

 feet, the hinder ones of which are palmated; but their tail is round and 

 elongated. They are aquatic animals also. One only is known, the 



M. coipus. (The Couia. ) Which lives in burrows along the banks of 

 rivers throughout a great part of South America. 



Hysteix, Lin. 



The Porcupines are known at the first glance by the stiff and sharp spines, 

 or quills (as they are called), with which they are armed, hke the Hedge- 

 hogs among the Carnaria. Their grinders are four throughout, with flat 

 crowns, variously modified by plates of enamel, between which are de- 

 pressed intervals. Their tongue is bristled with spiny scales, and their cla- 

 vicles are too small to rest upon the sternum and scapula, being merely 

 suspended by ligaments. They live in burrows, and have many of the 

 habits of the Rabbits. To their grunting voice, and thick truncated muz- 

 zle, are they indebted for being compared to the Pig, and for their corres- 

 ponding French appellation oi pore-epic. 



