DISTRIBUTION OF ANIMALS 537 



to him. Wonderful indeed is the intelligence of many of 

 the land animals, due in large part to their development 

 amid varied geographical conditions. 



DOUBLE BEAVER DAM AND BEAVER HOUSE 



In the foreground, one of the dams is plainly visible. In the background 

 is a second dam running almost parallel to the first. To the right in 

 the quiet water is the beaver house. To the left are stumps of trees 

 that were felled by the beavers. Picture taken in Estes Park, Colorado, 

 by Frank M. Hallenbeck of Chicago. 







Distribution of Animals. An examination of a globe 

 shows (1) that the land is massed around the north pole, 

 (2) that the three continental masses to the south are 

 separated from one another by wide seas, and (3) that 

 while two of these are connected by narrow strips of land 

 to northern continents, the third is entirely separated from 

 all other land. 



But slight changes in elevation would connect the northern 

 continents with one another. As they are so closely related 



