RODENTIA. 117 



We now pass to larger rodents than those of which we have hitherto spoken, hut of whicn 

 several have still well-developed clavicles. 



Of this number are 



The Beavers (Castor, Lin.), — 



Which 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 eacli 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 theirinternal 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 Castoreuin. 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 lower 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- 

 | ig 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 if 

 its yellow-coloured 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 coypxtt, Molina), which lives in burrows beside the rivers of South America. Its 

 yellowish-grey for, mixed with down at the root, is employed by batters like that of the Beaver, and is conse- 

 quently an important article of commerce. Thousands of their skins are sent to Europe. [1 his species, like the 

 Beaver, is easily tamed, and appears to withstand the climate of this country.] 



'I'm: Porcupines {Hystrix, Lin.) — 

 Are recognized at the first glance by the still' am! pointed (pulls 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 bj Lines of enamel, between which are depressed intervals. 

 Their tongue is roughened bj spiny scales. The clavicles are too small to lest on the sternum and 



BCapular, being merely suspended by the ligaments. They live in burrows, and have ver] tUUCb the 



habits of Rabbits. From their grunting voice, and thick truncated muzzle, thej have been compared 

 to I'igs, whence their French name of Porc-eptn or Poraq 



Tin, I'oik 1 cim;>, properly so called (Hi/strix, Cuv.), — 



Have the load more or less convex, on account of the developement of the nasal bones. Thej have 

 four toes before and live behind, furnished with stout claws. 

 That of Eirope ill. ertttata, Lin.) inhabits the South of Italy, Sicily, and Spam. Its quills are verj long, and 



