MK. H. OOLLETT O^f UYODKB LEMMUS iN JSfuKWAY. 383 



islands of Lofodeu and along the coast of Fiamarken. On the 

 islands the migrations soon cease when the sea is reached ; during 

 fine weather the animals will easily swim over fjords or lakes at 

 least two English miles broad *. 



Amongst the localities in Norway which are furthest distant 

 from the summer dwellings of the Lemmings are Smaalenene 

 (south-west of the Christianiafjord), the lowlands of Jadera (south 

 of Stavanger), and the tracts bordering on the southern part of 

 tlie lake Mjosen and on both sides of the Christianiafjord. But 

 during certain years of migration these parts of tlie country are 

 also covered with their swarms, and, on the whole, there perhaps is 

 no attainable point of the country which has not during one or 

 otheryear been visited by them. Each migration covers butacertain 

 district, but never spreads simultaneously over the whole country. 



The greatest migrations have generally taken place from some 

 of the following great complex systems of fells : — 



No. 1. Erom the plateaux of Langfjeldene and Jotinsfjeldeue, 

 sending swarms to the western portions of Ohristiania Stift, 

 Christiansand Stift, and the adjacent valleys of Bergen Sfcift. 



No. 2. Erom the plateaux of Dovre and the fells of Gudbrands- 

 dalen and Osterdalen to the northern districts of Ohristiania 

 Stift and the adjacent valleys of Trondhjem Stift. 



No. 3. Erom the fells in Trondhjem Stift towards the Swedish 

 frontier to the tracts bordering on the Trondhjemsfjord (and 

 Swedish Nordland). 



No. 4. Erom the fells in Nordland to greater or smaller portions 

 of Nordland (and the neighbouring parts of Swedish Lapland). 



No. 5. Erom the plateaux in the interior of Einmark to diiferent 

 parts of Einmark. 



The smaller migrations, as above stated, may only include the 

 neighbouring valleys which are adjacent to the plateaux. As 

 districts which in later years have been particularly visited by 

 their swarms, may be named (No. 3), for instance, the lowlands of 

 Inderoen and other of the innermost parts of the Trondhjemsfjord, 



* Here I may add a correction to a quotation by Mr. Crotch in one of his 

 papers (p. 32). Mr. Crotch writes that " in November 1868 [quoted by Lillje- 

 jeborg, infra] a ship sailed for fifteen hours through a swarm of Lemmings 

 which extended as far over the Trondhjemsfjord as the eye could reach." The 

 notice I gave Dr. Lilljeborg, and which is quite correctly quoted in his ' Fauna,' 

 i p. 327 (TJpsala, 1874), does not state fifteen hours, but a quart-er of an hour ; 

 and it was not a sailing ship, but a steamer. 



LINN. JOURN. ZOOLOGY. TOL. XHI. ' 28 



