358 



MIGEATION AND DIFFUSION 



[Ch. XXXIX. 



soon as tliej have crossed the river Penginsk^ at the head of 

 the gulf of the same name, they turn southward, and reach 

 the rivers Judoma and Okotsk by the middle of July ; a district 

 more than 800 miles distant from their point of departure. 



The lemings, also^ a small kind of rat, are described as 

 natives of the mountains of Kolen, in Lapland ; and once 

 or twice in a quarter of a century they appear in vast numbers. 



advancing along the ground and 

 thing,' 



devouring 



every green 



Innumerable bands march from the Kolen, through 

 Northland and Finniark, to the Western Ocean, which they 

 immediately enter ; and after swimming about for some time, 



Fig. 133. 





.^^v wJ.^^ 



The Leining or Lapland Marmot {Mus Lemmus, Linn.) 



perish. Other bands take their route 



through 



Swedish 



Lapland, to the Bothnian Gulf, where they are drowned in 

 the same manner. They are followed in their journeys by 

 bears, wolves, and foxes, which prey upon them incessantly. 

 They generally move in lines, which are about three feet from 



each other, and exactly parallel, 



gomo* 



dire c tly forward 



through rivers and lakes ; and when they meet with stacks of 

 hay or corn, gnawing their way through them instead of 



passing round.^ These excursions usually precede a rigorous 

 winter, of which the lemings seem in some way forewarned. 



Vast troops of the wild ass, or onager of the ancients, which 

 inhabit the mountainous deserts of Great Tartary, feed, during 

 the summer, in the tracts east and north of Lake Aral. In 

 the autumn they collect in herds of hundreds, and even 

 thousands, and direct their course towards the north of India, 

 and often to Persia, to enjoy a warm retreat during winter. f 

 Bands of two or three hundred quaggas (a species of wild ass) 

 are sometimes seen to migrate from the tropical plains of 



^ Phil. Trans., vol. ii. p. 872. 



f Wood's Zoograpliy, vol. i. p. 11. 





t 



1 



