THE SIBERIAN MIGRATION. 209 



and warm in the south, while in the middle zone, 

 comprising France, Germany, and the greater part 

 of Britain, the winters were cold and the summers 

 warm, as in Middle Asia and North America." " In 

 the summer time the southern species would pass 

 northwards, and in the winter time the northern 

 would swing southwards, and thus occupy at different 

 times of the year the same tract of ground, as is now 

 the case with the Elks and Reindeer." Very different 

 are the views of Professor Nehring on this subject. 

 According to him, the climate in Germany must 

 have been extremely cold and damp, resembling 

 that of Greenland, though perhaps not quite so 

 arctic. Professor Nehring does not at all believe 

 that southern and northern species of mammals could 

 have lived in Central or Northern Europe at the 

 same time; though of this we have undoubted geo- 

 logical evidence (pp. 72-75). He thinks that the 

 supposed commingling of southern and northern 

 types, which has actually been shown by Professor 

 Dawkins to occur, is either due to careless observa- 

 tion or to the fact that some of the species need not 

 necessarily have lived where their bones were found 



(P- 133). 



The most reliable conclusions as regards former 



conditions of vegetation and climate can be drawn, 

 according to Professor Nehring, from the smaller 

 burrowing mammals, such as the marmots, sousliks, 

 etc. He is of opinion that a great portion of 

 Northern Europe, where their remains have been 



