124 THE MIGRATION OF BIRDS. 



caused their present isolation on the various points 

 which still remain above the ocean. But whatever 

 the cause may have been is of little or no import- 

 ance, the facts remain as a convincing proof of 

 emigration on a wide and extensive scale. 



There is also some evidence to suggest that this 

 vast emigration of Ouzels, besides taking a direct 

 northern course over the Pacific, also followed a 

 route nearly due east across that ocean by way of the 

 Low Archipelago and chain of islands that extends 

 along the line of the Tropic of Capricorn to South 

 America, where their descendants live and flourish 

 in considerable numbers. Or we can account for 

 the presence of these Neotropical Ouzels by an 

 emigration from an Antarctic continent ; one stream 

 of emigrants retreating by way of New Zealand and 

 the Pacific Islands ; the other by way of Graham's 

 Land, the South Shetlands, and Patagonia. Various 

 faunal and floral links curiously enough bind New 

 Zealand to South America, and the most obvious 

 direction in which the connection once existed is 

 by the now glaciated Antarctic continent. The fact 

 that the Ouzels are not found in the Nearctic and 

 Ethiopian region is very suggestive of an emigration 

 from Antarctic latitudes, because Africa and North 

 America were by far the most isolated from South 

 Polar land ; although they were undoubtedly the 

 most important regions invaded by North Polar 

 species during the Post-Pliocene Glacial epoch. 

 The present distribution of the Snipes {Scolopax) 

 appears to denote ancient emigrations by routes 



