THE GLACIAL RANGE CONTRACTION, ETC. 113 



Iceland, but does not visit the Orkneys and the Shet- 

 lands for that purpose ; the Pink-footed Goose {Ajiser 

 bracJiyrJiyncJiiis) breeds on Iceland, but is absent from 

 the Faroes, the Orkneys, and the Shetlands ; the Bernacle 

 Goose {Bernida leiicopsis) is only an abnormal migrant 

 to the Faroes and the Shetlands, yet probably breeds 

 on Iceland. There can be little doubt that these species 

 keep well out to sea in performing their annual migra- 

 tions southwards, inasmuch as they are well-known 

 visitors to the coasts of the British mainland. Again, 

 the common occurrence of the Bean Goose {Anser 

 segetuni) and Bewick's Swan {Cygnns bezuicki) off the 

 British coasts in winter, and their absence from Iceland, 

 suggest unknown breeding grounds due north of these 

 areas in North-east Greenland, or in undiscovered land 

 between Emperor William Land and Spitzbergen. 

 Another interesting fact is presented in the migration 

 of the Black-tailed Godwit {Limosa inelaniira) to Iceland 

 and the Faroes. In its north-western migration this 

 species misses the British Islands entirely, and appears 

 to follow a route directly up the North Sea — probably 

 the river valley which once occupied the ancient land 

 between Britain and the continent — a vanished land 

 which was once the breeding ground of this Godvvit, as 

 it slowly emigrated north. Godwits seem to be ex- 

 ceptionally attached to old routes of passage. The Bar- 

 tailed Godwits {Liviosa riifd) passing up our coasts in 

 spring apparently go no further north than Spurn, and 

 then strike out to sea as if following an ancient and sub- 

 merged coast-line, or a continuation eastwards of the 

 Humber valley (see Map, p. 21) ; whilst the eastern 

 form of this Godwit {Liniosa rufa iiropygialis) appears 



