'38 



Human Physiology. 



chisels, rodent front teeth, with which he cuts down trees, 

 trims off their branches, and fashions stakes for his dam. With 

 his fore-feet (Fig. u), which are as good hands as those of 

 most monkeys, and adapted to more varied uses, he places his 

 timbers, plants his stakes, mixes his mortar, and builds his 

 dam and dwelling. The hind-foot (Fig. 12) is also very flexible 

 and useful, and he is web-footed here as an animal so aquatic 

 in his habits should be. With his broad, heavy, scale-covered 

 tail (Fig. 13) he drives his stakes, beats down his mortar, and 



Fig. ii. 



gives signals to his comrades. The beavers live in commum 

 ties and families. The pond created by the dam, and its 

 wooded banks, are the common domain. Each family has a 

 house of several apartments, proportioned to the number of its 

 members. The site of the dam, and its mode of construction, 

 show high powers of instinctive engineering. But the beaver 

 does not cut down trees, and make dams, and build houses, 



