ii] FEATURES OF ENVIRONMENT 57 



have an arctic ' facies ' or look, mostly cases of con- 

 vergent evolution, and the term arctic, if used for 

 such high-alpine organisms, must not be confounded 

 with boreal or polar. In fact true instances of boreal 

 derelicts on far southern mountains are very rare. 

 The idea was based upon the supposed similarity 

 between Scandinavia and the Alps, the favourite 

 example being the arctic hare. This Lepus varia- 

 bilis turns white in winter ; its present distribution 

 is circumpolar, from Scandinavia through Siberia to 

 Alaska and Greenland and Newfoundland, but also 

 in Scotland, Ireland, in the Pyrenees, Alps, the 

 Caucasus and in Japan. But none of the other 

 typical arctic animals are found in the Alps, neither 

 reindeer, polar fox, glutton or wolverene, lemming, 

 or snowy owl. Nor do any of the creatures, typi- 

 cal of high mountains in temperate countries, like 

 steinbok, rocky mountain goat, bighorn and argali, 

 marmot, chinchilla, extend their range into the polar 

 regions. We agree with those authorities who ex- 

 plain the occurrence of the comparatively few closely 

 related species of animals and plants in Scandinavia 

 and the Alps as due to independent immigration from 

 some common Central Asiatic centre. 



It is always difficult to prove a case of convergent 

 development. It can so easily be ruled out of court 

 in the present instance, because we know that during 

 the height of the glacial epoch the northern ice-sheet 



