ARCTIC ZOOGEOGRAPHY 1 63 



very recent land continuity and that it probably long antedates the 

 period when the bears, the deer, and the related fauna migrated from 

 the Old to the New World. 



CiRCUMPOLAR Land Connections and the Taylor- 

 Wegener Hypothesis 



The problem of the circumpolar land connections has of late years 

 entered into a new phase by the appearance of the Taylor-Wegener 

 hypothesis^^ of the lateral migration of the continental land masses 

 and the origin of the Arctic-Atlantic Ocean through a gradual drifting 

 apart of the American and Eurasian continental blocks. It implies 

 within comparatively recent times a practical continuity of north- 

 western Europe and northeastern North America and thus conforms 

 startlingly to the theoretical land connection postulated by Jager in 

 1867. But, contrary to the latter, the Wegener conception would 

 seem to imply an originally much wider gap between the continents 

 in the Bering Strait region, since, with the separation of Greenland 

 from Norway and the gradual widening of the gap between them by 

 the westerly drift of the American continent, an approach of north- 

 western America to northeastern Asia would seem to be a necessary 

 corollary. However, while the assumption of the Norway-Greenland 

 continuity might find favor with some zoogeographers as explaining 

 certain distributional facts, the doing away with the Beringian land 

 bridge, on the other hand, is certain to arouse a greater opposition. 



Need for Correlation and Unification of Observations in 

 Arctic Zoogeography 



It will thus be seen that the very latest aspect of the case brings 

 us back practically where we stood sixty years ago. It is true that the 

 innumerable polar exploration expeditions have vastly increased our 

 knowledge of the structure, distribution, and habits of the animals 

 peculiar to the Arctic Regions ; the nesting places and eggs of nearly 

 all the polar species of birds unknown sixty years ago have been found 

 and described ; and many equally curious and interesting observations 

 have been made in the interval. A list of all the literature on these 

 and related subjects would fill a good-sized volume. Hundreds and 

 thousands of specimens collected during these years fill the shelves of 

 many museums. But, unfortunately, all this mass of information 

 remains scattered and uncorrelated. Moreover, it should be emphasized 

 that the aims and methods of zoogeography have undergone a refine- 

 ment during recent years which makes the earlier accumulations of 



" F. B. Taylor: Bearing of the Tertiary Mountain Belt in the Origin of the Earth's Plan, Bull. 

 Geol. Soc.of Amer., Vol. 21, 1910, pp. 179-226; Alfred Wegener: Die Entstehung der Kontinente und 

 Ozeane, 3rd edit., Brunswick, 1922 (first publication in Petermanns Mitt., Vol. 58, Part I, 1912). 



