RECENT EMIGRATION 



179 



even in some cases far beyond the Arctic Circle to the 

 North Cape, their Post-Glacial Emigration having been a 



NORTHERN LIMITS 

 IN WEST EUROPE. 



lat. 66|°. 



lat. 66 J°. 



lat. 67°. 



lat. 71^. 



lat. 66^". 

 South of Baltic. 



lat. 65°. 



lat. 70"', 



lat. 58^ 

 Denmark. 



lat. 70'. 



lat. 66i°. 



lat. 70". 

 Denmark. 



lat. 69". 



lat. 65°. 



lat. 661°. 



lat. 6f. 

 lat. 70°. 

 South of Baltic, 

 lat. 6q\ 

 lat. 66i". 

 lat. 71". 

 lat. 66J°. 

 lat. 64\ 

 lat. 66°. 

 lat. 61°. 

 lat. 57°. 

 lat. 66*°. 



purely continental one to Scandinavia. Of the twenty- 

 one resident species we find that in no less than fifteen 

 cases the birds that are gradually emigrating northwards 

 in our islands did not reach Scandinavia by a Post- 

 Glacial Emigration across our area ; whilst in the six 

 instances of which we have evidence that such a line of 

 Emigration did actually take place, some change of 

 climate or of arboreal conditions has for a time lowered 

 the breeding range in our area by extermination, and the 

 lost ground is now slowly being recovered. With two 



