148 VERTEBRATA. MAMMALIA. 



ture, covered with a black, dry skin, raised in the 

 form of scales. There are five toes on each of the 

 feet. 



There is but a single species (C. Fiber) inhabit- 

 ing the rivers of Europe and North America. Swim- 

 ming and diving with great ease, a great part of its 

 existence is passed in the water, on the banks of 

 which, associating in companies, it displays those 

 architectural instincts of which we are about to speak. 

 Choosing a piece of water sufficiently deep to be 

 unfrozen in winter, a running stream if possible, the 

 Beavers fell young trees on the bank above the place, 

 and float them down. They then form a dam com- 

 posed of branches, twigs, stones, and clay, which is in- 

 creased every year, and soon forms a strong and solid 

 wall, and keeps the water at an even height. Above 

 this dam, each family constructs a hut of similar 

 materials, having an aperture under water, in and 

 around which they store up vast quantities of young 

 twigs, and bark of trees, for the winter's sustenance. 

 The stories told of the distribution of labour among 

 them, the superintendence of an overseer, who gives 

 orders with his tail, the driving of huge stakes into 

 the ground, the drawing of materials upon the tail, 

 the using of it as a plastering trowel, and such like, 

 are absurd and fabulous. 



The use which is made of their fine and soft fur, 

 in the manufacture of hats, causes the skins of these 

 animals to be an important item in our North Ame- 

 rican fur trade. From the eagerness with which 

 they have been pursued, they are now become scarce, 



