FORMING A LIVING PONTOON. 81 



the water, the foremost advance, and swimming across, form 

 a kind of floating, or, to use a military phrase, complete pon- 

 toon-bridge, the head of each supported by the hinder part of 

 that before it. When a communication is thus formed between 

 the shores, the remainder of the army pass rapidly over the 

 backs of the supporters, and gain the opposite strand. Strange 

 as this may seem," he adds, " the contrivances which natu- 

 ralists agree are resorted to both by the marmot and the grey 

 squirrel, for the purpose of crossing rivers, appear as_ extra- 

 ordinary, though well authenticated; and what has thus 

 been mentioned concerning the lemming, will, I doubt not, 

 be received with attention by those, who have made natural 

 history more particularly their study, and can the better 

 judge of the extraordinary instinct and sagacity of the animal 

 creation/' 



Though the swimming powers of the lemming may be 

 considerable, it would not appear that they can hold out for 

 any very great length of time ; and if the water should be 

 broad, a large portion of them must inevitably perish. This 

 was evidenced some years ago in the great lake Siljan, in 

 Eastern Dalecarlia. " All those that were fallen in with near 

 to the northern shore, whence they took their departure," 

 so we are told by an eye-witness, " were strong and vigorous, 

 and exerting themselves to the utmost in contending with 

 the waves. Farther out in the lake they appeared exhausted, 

 and seven miles from the starting-point large numbers were 

 found dead." 



During their migrations, great multitudes of lemmings are 

 drowned, and myriads are destroyed by birds and beasts of 

 prey, that follow in their tracks, more especially by the 



VOL. n. G 



