THE ARCTIC FAUNA. 139 



to the south of France, but Mr. Barrett-Hamilton 

 announced to us a short time since that Dr. Gadow 

 had discovered some skeletons with their skins still 

 preserved in a cave in Northern Portugal. These 

 were found to belong to the Scandinavian Lemming 

 (M. lemmus) y and the author incidentally expressed the 

 opinion that there was some possibility of this species 

 still inhabiting the mountains of Spain. 



The Lemming multiplies with great rapidity under 

 favourable conditions. In speaking of his experiences 

 in Siberia Dr. Brehm says (p. 79): "All the young of 

 the first litter of the various Lemming females thrive, 

 and six weeks later at the most these also multiply. 

 Meanwhile the parents have brought forth a second 

 and a third litter, and these in their turn bring forth 

 young. Within three months the heights and low 

 grounds of the tundra teem with lemmings, just as 

 our fields do with mice under similar circumstances. 

 Whichever way we turn we see the busy little crea- 

 tures, dozens at a single glance, thousands in the course 

 of an hour. But the countless and still increasing 

 numbers prove their own destruction. Soon the lean 

 tundra ceases to afford employment enough for their 

 greedy teeth. Famine threatens, perhaps actually sets 

 in. The anxious animals crowd together and begin 

 their march, hundreds join with hundreds, thousands 

 with other thousands, the troops become swarms, the 

 swarms armies. They travel in a definite direction, 

 at first following old tracks, but soon striking out 

 new ones; in unending files defying all computation 



