RODENTIA. 
117 
We now pass to larger rodents than those of which we have hitherto spoken, but of which 
several have still well-developed clavicles. 
Of this number are 
The Beavers {Castor, Lin.), — ■ 
Wliieh are distinguished from all other rodents by their horizontally-flattened tail, of a nearly oval 
form, and covered with scales. They have five toes on each foot, the hinder being webbed, and a 
double and oblique nail on the digit next the thumb. Their grinders, four in number above and 
below, with flat crowns, appear as if formed of a doubled bony fillet, exhibiting one deep indentation 
on their internal border, and three on the outer edge above, and the reverse below. 
They are rather large animals, and are aquatic in their mode of life ; their feet and tail assisting 
them in swimming. As they subsist chiefly on bark and other hard substances, their incisive teeth 
are very robust, and grow as rapidly from the root as they wear at the tip. By means of them they 
are enabled to cut down trees of various kinds. 
Large glandular pouches, which terminate on the prepuce, secrete a pommade of very pungent 
odour, which is employed in medicine under the name of Castoreum. In both sexes, the organs of 
generation terminate within the extremity of the rectum, so that they have only one external orifice. 
The Beaver of Canada {C. fiber, Auct.). — Surpasses the Badger in size, and is, of all quadrupeds, the most indus- 
trious in fabricating its dwelling ; to erect which many work in concert, in the most retired districts of North 
America. 
Beavers choose water of such a depth as is not likely to be frozen to the bottom, and, whenever possible, run- 
ning streams, that the wood which they cut above, may be carried downwards by the current to where they 
require it. They maintain the water at an equal height, by dams constructed of branches of trees, mixed with 
clay and stones, and repair them year after year, till a hedge is at length formed by the germination of part of the 
materials. Each hut serves for two or three families, and is divided into two apartments ; the upper dry, for the 
habitation of the animals ; the low'er under water, for the provision of bark. The latter only is open, having its 
entrance under water, without any communication with the land. The huts are formed of interlaced twigs and 
branches,.having their interstices closed up with mud. There are always several burrows along the bank, in which 
these animals seek for refuge when their huts are attacked. They only inhabit them during the winter ; dis- 
persing in summer, at which season they live solitarily. 
The Beaver is easily tamed, and accustomed to feed on animal substances. Those of Canada are of a uniform 
reddish brown ; and their fur, as every one knows, is in much request for hatting. It is sometimes flaxen- 
coloured; at others black, or white. We have been unable to ascertain, on the most scrupulous comparison, 
whether the Beavers which inhabit burrows along the Rhone, the Danube, the Weser, and other rivers of Europe, 
are specifically different from those of America ; and whether the vicinity of man prevents those of the eastern 
continent from building. 
The Coypu {Myopotamus, Commerson) — 
Resembles the Beaver in size, in having four molars almost similarly compressed, in the robustness of 
its yellow-eoloured incisors, and in having five toes to each foot, those of the hinder palmated ; but its 
tail is long and rounded, [and its skull dissimilar]. 
We only know one (Mus coypus, Molina), which lives in burrows beside the rivers of South America. Its 
yellowish-grey fur, mixed with down at the root, is employed by hatters like that of the Beaver, and is conse- 
quently an important article of commerce. Thousands of their skins are sent to Europe. [This species, like the 
Beaver, is easily tamed, and appears to withstand the climate of this country.] 
The Porcupines {Hystrix, Lin.) — 
Are recognized at the first glance by the stiff and pointed quills with which they are armed, somewhat 
as in the Urchins or Hedgehogs, among the Carnaria. Their grinders are four in number above and 
below, with flat crowns differently modified by lines of enamel, between which are depressed intervals. 
Their tongue is roughened by spiny scales. The clavicles are too small to rest on the sternum and 
scapular, being merely suspended by the ligaments. They live in burrows, and have very much the 
habits of Rabbits. From their grunting voice, and thick truncated muzzle, they have been compared 
to Pigs, whence them French name of Porc-epm or Porcupine. 
The Porcupines, properly so called {Hystrix, Cuv.), — 
Have the head more or less convex, on account of the developement of the nasal bones. They have 
four toes before and five behind, furnished with stout claws. 
That of Europe (//. cristata, Lin.) inhabits the South of Italy, Sicily, and Spain. Its quills are very long, and 
