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CHAPTER III 



large warm-blooded animals. The Arctic Fox {Alopex lagopus L.) has been tracked 

 on the ice at about 85° north (Braestrup, 1941, p. 19), also half-way between Green- 

 land and Iceland (Saemundsson, 1939, p. 3). Proofs of still longer distances 

 covered are available for the Reindeer (Rangifer tarandus L.) since animals with 

 owner's mark on the ears have repeatedly been observed in Spitzbergen (Ingstad, 

 1948, p. 239 a.f.), which they must have reached travelling on the ice from Novaja 

 Zemlja, at least, a distance of about 770 km. With this in mind it seems astounding 

 that a special race of the Reindeer, sbsp. pearyi All., could establish itself on Elles- 

 mere Island (fig. 53), separated from Greenland only by narrow ice-covered sounds. 

 Perhaps this is due to a more complete isolation in earlier periods of the Pleisto- 

 cene, and stragglers may not be accepted in the herds. 



Cold-blooded and, probably, small warm-blooded animals, such as the Lem- 

 mings, cannot traverse the sea-ice actively. They may do so by passive ice-transport 

 carried by currents, as has been suggested for the Waterbeetle Colymhetes dolabra- 

 tus Payk. (from Greenland to Iceland; Lindroth, 193 1, p. 529) and is still more 

 probable for the high-arctic circumpolar Staphylinid Micralymma brevilingue 

 Schie. {dicksoni Makl.), inhabiting the tidal zone. Yet a general application of 

 this kind of dispersal to the soil-bound fauna is made highly dubious by the existing 

 faunal barrier between Greenland and Baffin Island, existing in spite of the fact 

 that surface currents rather favour westward transport across the Davis Strait 

 (Orchymont & Brown, 1940, fig. i). 



(d) Extension of land in the far north may have been more favourable during 

 earlier parts of the Pleistocene, or in Tertiary time. This, to my mind, is the clue 

 to the circumpolar type of distribution, or at least to the frequent occurrence of 

 animals so distributed. 



In a previous paragraph of this chapter (p. 253 a.f.) I have tried to show that Ice- 

 land and Greenland are so firmly linked to Europe, from a zoogeographical point of 

 view, that the assumption of an uninterrupted land-connection (or almost so) with 

 the European mainland seems unavoidable. At the same time, however, it was 

 stressed that a westward prolongation of this "bridge", to Baffin Island, could 

 not be traced on faunal evidence. This will be still more evident if we consider the 

 pattern of subspeciation among circumpolar animals (below). It is a fact beyond 

 any doubt that the circumpolar area of very few animal species, if any, has 

 incorporated America from Eurasia, or vice versa, by way of Greenland-Baffin 

 Island. 



This being admitted, the Bering Strait, or rather the passage now occupied by 

 this strait, is the historical link between the Palaearctic and Nearctic regions. 



The idea is not at all revolutionary. It has been advocated by many skilled bio- 

 geographers (Matthew, 1915; Mayr, 1946; Simpson, 1947; &c.). And the conditions 



