Order 5. RODENTIA. 105 



We now pass to larger rodents than those of wliich we have hitherto spoken, but of whicli 

 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 binder 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 bard substances, their incisive teeth 

 are very robust, and grow as rapidly from the root as they wear at tlie 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 anunals ; 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 wliich 

 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 tlaxen- 

 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 difterent from those of America ; and whether the vicinity of man prevents those of the ea&tern 

 continent from building. 



The Coypu (Mi/opotatntts, Commerson) — 

 Resembles the Beaver in size, in having four molars almost similarly compressed, in the robustness of 

 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 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, hke 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 stiflT 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 their French name of Porc-epm or Porcupine. 



The Porcupines, properly so called {Hystrix, Cuv.), — 



Have the bead more or less convex, on account of the developement of the nasal bones. They have 

 ^ur toes before and five behind, furnished with stout claws. 

 That of Europe (//. cristala, Lin.) inhabits the South of Italy, Sicily, and Spain. Its quills are very long, and 



