PAST GEOGRAPHICAL MUTATIOXS 23 



and in the brick earths of England — a fact in itself sug- 

 gestive of a former land connection between Greenland, 

 and Europe. Of the others, Myodcs torquatus may have 

 been introduced by man, and Lcpns glacialis on icebergs 

 None of the land birds, however, especially of South 

 Greenland, show very striking Palaearctic affinities ; and 

 this to a great extent may be due to the present glacial 

 conditions of the country, north of 65 on the east coast^ 

 combined with the wide water areas. The land birds 

 indicate a more remote connection of South Greenland 

 with Europe than with America, inasmuch as all the 

 terrestrial species recorded by Hagerup {Birds of Green- 

 land, 1 891) as breeding in South Greenland are Nearctic 

 forms of Palaearctic species, Palaearctic species that have 

 invaded America from Eastern Asia, or species common 

 to both regions. Iceland, as might be expected, shows 

 more affinity with Europe in its avifauna, only one species 

 belonging otherwise exclusively to the Nearctic region, 

 viz. Clangiila islandica. It also contains a Wren 

 [Troglodytes borcalis) found elsewhere only in the Faroes, 

 and which is most nearly allied to the Norwegian T. bcr- 

 gensis and the St. Kildan T. hirtensis — a fact which 

 strongly indicates a purely Palaearctic emigration. But 

 the most interesting avian proof of a more continuous 

 land area between Greenland and Europe is that fur- 

 nished by the Wheatear {Saxicola ccnanthe^. The Wheat- 

 ears breeding in Iceland and perhaps North Greenland 

 are distinctly larger than the typical European form, and 

 pass the British Islands regularly oh passage during 

 April and May, when the individuals of this species that 

 spend the summer with us are already breeding. We 

 are thus able actually to prove that this route is followed. 



