THE STRUCTURE AND ACTIVITIES OF MAMMALS 415 



and fall migrations. They covered an area of about thirty-six 

 hundred miles from north to south, and two thousand miles from 

 east to west. Similar migrations are made by the caribou in 

 Newfoundland (Fig. 282). 



Fig. 282. 



-The Newfoundland caribou in migration. (From Dugmore.) 



The lemmings of Scandinavia (Fig. 283) are celebrated for 

 their curious migrations. They are small, gnawing animals about 

 three inches in length. " At intervals, averaging about a dozen 

 years apart, lemmings suddenly appear in cultivated districts 

 in central Norway and Sweden, where ordinarily none live, and 

 in a year or two multiply into hordes which go traveling straight 



