THE SIBERIAN MIGRATION. 2 19 



at the commencement of the Glacial period the great 

 mammals of Northern Siberia either perished or 

 migrated southward. From there they gradually 

 penetrated into European Russia. He believed that 

 before the Glacial period a connection qxisted 

 between the Aralo-Caspian Sea and the Arctic 

 Ocean, carrying warm water northward. The gradual 

 disappearance of this marine channel caused a 

 decrease of warmth in Northern Asia, so that large 

 accumulations of frozen soil and ice were formed, 

 which still more depressed the temperature. This, 

 he suggested, probably took place at the time when 

 the Glacial period commenced in North-western 

 Europe. 



It has been urged against these views of Tcherski 

 and Brandt, that the bone beds in the Liakov Islands 

 (New Siberian Islands) rest partly upon a solid layer 

 of ice of nearly seventy feet thick. This mass of ice, 

 it was thought, must have accumulated during the 

 Glacial period. As the bones rest upon it, the 

 mammals could only have lived in those islands in 

 more recent times, after the Ice- Age had passed away. 

 Nothing, apparently, can be clearer, and yet in the 

 face of this seeming proof one feels, as I have men- 

 tioned before, that if such an extraordinary revolution 

 of climate as is implied by this admission had taken 

 place, we should be able to perceive the traces 

 throughout the northern hemisphere. In this di- 

 lemma, a suggestion made by Dr. Bunge, who visited 

 the New Siberian Islands recently at the instance of 



