158 ME. W. D. CROTCH ON THE LEMMING. 



and that during the autumn, when the Lemmings first reach my 

 neighbourhood, their number is never large ; but after a winter 

 spent beneath the snow, they begin to breed with tbe first days 

 of summer, and thus develop the extraordinary multitude which 

 is, as it well may be, the astonishment and terror of the country. 

 I think, then, that excessive reproduction results from, and does 

 not cause migration. 



The second theory is the mere expression of a popular supersti- 

 tion which has been conclusively falsified during the greater mi- 

 gration of 1876-1877 as well as previously, and may, I think, 

 be entirely omitted from our consideration. 



The third theory, that these migrations follow the natural declivi- 

 ties of the country, will be best met by a reference to the diagrams 

 (PI. XIII.). The chart (fig. 1) shows the general main declivities 

 of the Scandinavian peninsula. Kg. 2 is a plan of the district in 

 which I have observed three migrations in ten years ; in this the 

 diagonal path of the Lemmings swimming across my lake in 

 Heimdalen is very remarkable, and was confirmed by almost 

 daily observation. Fig. 3 exhibits, in section, the foregoing plan. 

 I also give a statement from the ' Verdens Gang,' No. 125, for 

 Oct. 23, 1875, Christiania, for what it may be worth. " The proper 

 home of the Lemaen is the Norsk High-Fjeld, both the Lang- 

 fjelde and Kjolen, whence they migrate to the sea, either to the 

 North Sea, the Atlantic Ocean, or the Grulf of Bothnia." Then 

 follows a list of remarkable migrations : — 



By Throndhjem, west 1580 



„ Nordfjord „ 1648 



„ Tornea, east 1697 



„ Lulea „ 1737 



„ Umea, „ 1747 



„ Throndhjem, west 1757 



„ Kongsberg, south 1770 



. „ Hernosand, east 1823 



„ Lyksele, „ 1831 



„ Bossekop, west 1833 



„ Karrasuanda, east 1839 



Now, assuming these facts to be accurate, which I confess 

 I think, considering the ridiculous and improbable statements 

 which accompany them, to be at least doubtful, there does cer- 

 tainly seem, at first sight, reason in tbe supposition that these 



