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 



