1915] 



WILLE FLORA OF NORWAY 105 



along the coast southward and northward to its present 

 limits. 



It also appears, according to L Hagen ('12), that the case 

 is similar with regard to a number of mosses, a direct migra- 

 tion from England to Norway being assumed. Hagen has so 

 little faith, however, in the ability of these plants to migrate 

 by leaps and bounds, that he supposes a post-glacial land con- 

 nection with England, over which migration might gradually 

 take place. 



This land bridge between Norway and England was origin- 

 ally hypothetically constructed for the pre-glacial times by 

 L. Stejneger ('07), who considers it necessary on zoogeo- 

 graphical grounds. At the conclusion of his paper he says: 



"I think I may safely claim to have made it appear probable: 



"1. That if the characteristic and important portion of the 

 animals and plants of west Norway, called the 'Atlantic' biota, in- 

 vaded that country from Scotland, it came by way of a land bridge 

 connecting northern Scotland with western Norway north of 59° 

 north latitude. 



2. That this land bridge existed after the first (Scandinavian) 



a 



great glaciation. 



"3. That part of this biota surely survived the second (Scandin- 

 avian) glaciation along the west coast of Norway, and that possibly 

 the climate was not too severe for all to survive. 



"4. That there is a possibility of a reestablishment of the land 

 bridge during the 'Upper Forestian' stage with its congenial, more 

 continental climate, during which the tenderer species may have 

 immigrated, in case it should be proven that they could not have 

 come with the hardier ones." 



As will appear from the foregoing pages, I have also main- 

 tained ('05) that during the Last Glacial Period there was a 

 stretch of coast in Norway that was free from ice, where some 

 arctic plants, and, of course, also animals, were able to survive 

 that period. 



Since then Gunnar Andersson and Selim Birger ( '12) have 

 endeavored to give to the facts that favor this view the inter- 

 pretation that the entire arctic flora element must have im- 

 migrated through Sweden, and followed the receding margin 

 of ice. I consider their arguments on this point so unconvinc- 



