ARCTIC ZOOGEOGRAPHY 159 



at his command (collections of British Museum, etc.) is "totally 

 inadequate" for the purpose of determining the characters of the 

 Eurasian D. torquatus and its exact kinship with the American D. 

 rubricatus, to which it is "undoubtedly very closely related. " On the 

 other hand, he admits that, as G. M. Allen has suggested, D. ru- 

 bricatus richardsoni and D. groenlandicus may intergrade somewhere to 

 the north of Hudson Bay. However, from his treatment of the case 

 and the data submitted it is concluded that the Novaya Zemlya 

 subspecies is descended from the Siberian D. torquatus, and the eastern 

 American D. r. richardsoni from the Alaskan D. rubricatus; and that, 

 further, the Old World D. torquatus and the New World D. rubricatus 

 in their turn are descended one from the other or both from a common 

 ancestor. The plain inference is that it would be illogical to speak of 

 the polar area as a center of distribution of the collared lemmings, 

 especially as fossil remains of at least two species of Dicrostonyx, 

 one apparently more nearly related to D. torquatus, the other to D. 

 hudsonius, are common in Pleistocene deposits of Great Britain, 

 Ireland, France, and Germany. 



Other polar subspecies show similar indications of closer relation- 

 ships toward their congeners occupying adjacent territory to the south 

 than to the corresponding polar forms inhabiting other parts of the 

 Arctic area, but in no case has there been any recent scientific investi- 

 gation like that of the lemmings. It is not the place here to go into 

 the matter further, but an additional reason for giving the above 

 example in such detail was to show how defective our knowledge of the 

 geographical distribution is even when dealing with the larger and 

 better known animals of the Arctic. A large amount of material has 

 been gathered, though by no means enough, but it is scattered among 

 a dozen large museums and there has been no concerted effort to have 

 it brought together in one place and studied by a single mind capable 

 of realizing the ultimate problems involved and at the same time 

 qualified to treat the taxonomic questions according to modern 

 conceptions and requirements. And yet, only in this way will it be 

 possible to unravel within a reasonable time the intricate questions 

 connected with the origin, evolution, and present geographical dis- 

 tribution of the polar fauna. 



Theory of Latitudinal Dispersal in the Arctic 

 Faunae Realm 



The early hypotheses of the north pole as a center of origin or of 

 zoogeographical distribution did not only, or even mainly, have 

 reference to what is now the strictly polar fauna. They were chiefly 

 concerned with the boreal, or perhaps rather arctogean, animals in 

 general and tried to explain how it happened that this category of 



