ScHARFF — On the Origin of the European Fauna. 453 



that this migration passed across a hmd-connexion which united Asia 

 Minor and Greece, but that the later Siberian one took a very dif- 

 ferent course, as we shall see presently. 



'Now, several naturalists, who have studied the problem of the 

 former Siberian emigration of Mammals, have felt that if the physical 

 geography of Eastern Europe in later Pliocene times had been what it 

 is at present, we should have some evidence in that region of a migra- 

 tion from Asia. But in the older strata no Siberian Mammals are to 

 b3 met with, and it has been suggested that nothing less than a very 

 formidable barrier could have prevented the Siberian fauna from in- 

 vading the neighbouring continent. 



I think the distinguished llussian zoologist, Prof. Brandt, was the 

 first to draw attention to this circumstance. In referring to the 

 former occurrence of mammoths in I^orthern Siberia, he says (12, 

 ]). 86) : — " The large extension of forests in the north may have taken 

 place at a time when an arm of the sea stretched from the Aralo- 

 Caspian to the Arctic Ocean, and conducted warm water to it from 

 Central Asia. The gradual disappearance of this connexion may have 

 induced a steady decrease of warmth inlTorthern Asia, so that ice and 

 frozen soils formed, which lowered the temperature still more. All 

 this may have happened at the time the Glacial Period commenced in 

 Europe. The large Mammals of Northern Asia migrated southward in 

 •consequence of the deleterious influence of the cold on the vegetation 

 in the north. From there, they were now able to gradually proceed 

 west, as the arm of the sea, which formerly had prevented extension 

 of range in that direction, had disappeared." Prof. Boyd Dawldns 

 •expressed himself in very similar language, a year later (22c), as 

 follows: — "Before the lowering of the temperature in Central Europe 

 the sea had already rolled through the low coiintry of Bussia, from 

 the Caspian to the Wliite Sea and the Baltic, and formed a barrier to 

 western migration to the Arctic Mammals of Asia." 



But the view of Professor Dawkins differs from that of Prof. 

 Brandt, and also from that of Mr. Koppen (53, p. 42), who likewise be- 

 lieved in a connexion between the Caspian and the Arctic Ocean, in one 

 material point, in so far that he places his connexion to the west of 

 the Ural Mountains instead of to the cast. Since Tcherski has shown 

 that Western Siberia is largely covered by freshwater deposits, the 

 iissumption that the Aralo-Caspian had been in direct communication 

 with the Arctic Ocean, as recently as the Pliocene Epoch, can no 

 longer be maintained ; biit, as we shall see presently, there is some 

 •evidence in favour of a European connexion between the two seas. 



