584 ZOOLOGY. 



plateaus of Scandinavia down arid into the sea ; the object 

 and origin of which are inexplicable, and are not indicative 

 of much intelligence. From this and their nest- building 

 habits, rodents are, as a rule, not unlike birds ; and Owen, for 

 these reasons, ascribes to them a low degree of intelligence. 

 Granting that this is the case, an exception to this rule is 

 seen in the social beavers, which evince a high, exceptional 

 degree of intelligence. Beavers build a dam in a running 

 stream so as to create an artificial pond as a refuge when at- 

 tacked, as well as a subaquatic entrance to their lodges and to 

 their burrows in the banks of the streams they inhabit. Bea- 

 ver dams are built at first by a single pair or family, and are 

 added to from year to year, and afterwards maintained for 

 centuries by constant repairs. They are built of sticks and 

 mud, usually curve up stream, with a sloping water-face. 

 Beavers lay up stores of wood for winter use in the autumn ; 

 they can gnaw through trees eighteen inches in diameter ; they 

 work mostly at night. They often construct artificial canals 

 for the transportation of the sticks of wood to their lodges. 

 This, in the opinion of Mr. Morgan "is the highest act of 

 intelligence performed by beavers." When ponds do not 

 reach hard-wood trees or ground in which they can burrow 

 for safety, they will 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 con- 

 nection, by water, with the trees that supplied them with 

 food, as well as to relieve them from the tedious, and per- 

 haps impossible, task of moving their cuttings five hundred 

 feet over uneven ground, unassisted by any descent. " Bea- 

 vers, in swimming, use their tail as a scull, and the hind 

 feet being webbed, its propelling power while swimming is 

 very great. They carry small stones and earth with their 

 paws, holding them under 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 together 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, 



