242 FIRST LESSONS IN ZOOLOGY. 



canals for the transportation of the sticks of wood to their 

 lodges. This, in the opinion of Mr. Morgan, "is the high- 

 est act of intelligence performed by beavers. " When 

 ponds do not reach hard-wood trees or ground in which 

 they can burrow for safety, they build canals with dams, 

 and so excavate them that they will hold the surface 

 drainage. Morgan describes one canal about 161 metres 

 (523 feet) long which " served to bring the occupants of 

 the pond into easy connection, by water, with the trees 

 that supplied them with food, as well as to relieve them 

 from the tedious, and perhaps impossible, task of moving 

 their cuttings five hundred feet over uneven ground, unas- 

 sisted by any descent." Beavers, in swimming, use their 



FIG. 241. Head of common mouse, showing the incisor teeth. 



tail as a scull, and, the hind feet being webbed, the propel- 

 ling power while swimming is very great. They carry 

 small stones and earth with their paws, holding them un- 

 der the throat, and walking on their hind feet. They use 

 the tail in moving stones, working it under so as to "give 

 it a throw forward." Beavers are very social, working to- 

 gether and storing up wood in common. " A beaver family 

 consists of a male and female, and their offspring of the 

 first and second years, or, more properly, under two years 

 old. The females bring forth their young from two to five 

 at a time, in the month of May, and nurse them for a few 

 weeks, after which the latter take to bank." They attain 

 their full growth at two years and six months, and live from 

 twelve to fifteen years. 



The largest of all existing rodents is the capybara of 

 South America, which looks like a pig. This is succeeded 



