THE ARCTIC FAUNA. 159 



thrive in Ireland, which has a particularly mild climate 

 in winter, and be absent from so many continental 

 stations where the temperature more resembles that 

 of its native home? If we suppose that the European 

 Hare migrated to Europe from the east, after the 

 Arctic Hare had become established in Western 

 Europe, and drove the latter into the mountains 

 or northward whenever the two came into contact, 

 we should have, it seems to me, a better ex- 

 planation of the range presented by the two species. 

 I was formerly of opinion that the European Hare 

 had come with the Siberian animals from Siberia, 

 but it appears to me more likely now, that it reached 

 our continent with the Oriental migrants, and only 

 then joined the Siberians in Eastern Europe. 



The evidence in favour of a former land-connection 

 between Scandinavia and Greenland, rests on many 

 other facts besides those already brought forward. 

 That some form of land-connection formerly existed 

 between Europe and Greenland is now indeed almost 

 universally accepted. That it was situated more to 

 the south between Scotland and Greenland is a sup- 

 position which has been actively supported by many 

 leading authorities, but it seems to me that if such a 

 land-bridge existed, it must have been in very early 

 Tertiary times, whilst the northern one, such as I 

 have indicated, may have originated later and per- 

 sisted until a recent geological date. 



The distribution of few groups of animals is now 

 better known than that of the larger butterflies and 



