MR. W. D. CROTCH ON THE LEMMINft. 159 



migrations follow the watershed, siace the backbone of mountains 

 in Norway runs nearly north and south. Thus reference to figs. 

 2 & 3, PI. XIII., which gives the course of the Lemmings in 1867- 

 68, 1870-71, and 1875-76, clearly shows that the natural slopes were 

 not followed ; and, again, reference to fig. 1 likewise shows that the 

 main valleys in Norway run nearly north and south ; whilst we 

 find but one so-called southerly migration, that " by Kongsberg in 

 1770," respecting which I should much like to know more. 



At all events, all these migrations end in the sea, and the Lem- 

 mings do not retrace their steps. Again, though four or five gene- 

 rations occur in one summer, tbe richest grass and the quietest 

 quarters do not tempt the wanderers to remain and settle. I know 

 nothing more striking in natural history than to see the holes, tbe 

 well-marked runs, and the refuse of these restless creatures which 

 so strangely appear and vanish, while their congener, the Field- 

 Vole, remains in quiet possession of the quarters from which he 

 was temporarily ousted. Probably this same Field- Vole is the 

 only quadruped which does not wage successful war on the Lem- 

 mings ; and the drawing given in the ' Verdens G-ang ' I. c, only 

 fails from omitting their enemies ; in fact, if they were all depicted, 

 there would be no room for the victims. 



I tbink it must be admitted that, whether instinct be inherited 

 reason or not, its primary object is for the benefit of the species. 

 Here, however, this definition seems to fail just when it need not 

 do so. By staying where they are, or by migrating southwards, 

 most of the emigrants might live in such peace as is allotted to a 

 Lemming ; by migrating westward, or even eastward, they neces- 

 sarily are drowned ; but if in former ages land existed where the 

 sea now rolls, a motive is found for these marvellous migrations, 

 and collaterally a strong proof that what we call instincts are but 

 the blind and, sometimes, even prejudicial inheritance of previously 

 acquired experience. 



The researches of the naturalists of the ' Challenger ' Expedi- 

 tion have disclosed the existence of at least three ridges of sub- 

 merge d land in the Atlantic Ocean, extending some thousands of 

 miles nortb and south of which' the highest summits still remain 

 as islands ; and although the intervening valleys are of enormous 

 depth, it may yet well be that lateral connecting ridges exist 

 between those already discovered. Of course it is most impro- 

 bable that the Lemmings ever journeyed so far south ; probably 



14* 



