THE SIBERIAN MIGRATION. 233 



originated in Siberia, and of which we have some 

 evidence that they crossed Central Europe in their 

 westward course, had now reached the great river 

 just alluded to, which some geologists believe to have 

 been the Rhine. 



I have had occasion to refer to a number of British 

 mammals (p. 202) some of which are now extinct 

 which I believe to have migrated across the plains of 

 continental Europe direct from Siberia. There were 

 twenty-six species of these Siberian mammals; and no 

 less than ten of these occur in the Forest-Bed. None 

 appear in any older British deposit. It is perfectly 

 clear, therefore, that the Forest-Bed must have been 

 laid down after their immigration into Europe. They 

 probably wandered to Western Europe very soon 

 after crossing the eastern boundaries of our conti- 

 nent ; the deposits in which they are found are there- 

 fore contemporaneous. But we have learned above 

 (p. 208), that the beds in Eastern Europe in which the 

 Siberian mammal-remains are found are more recent 

 than the lower boulder-clay. As already stated, the 

 Forest-Bed must also be more recent than the lower 

 continental boulder-clay, and should be included in 

 the pleistocene series. 



That the Forest-Bed is an inter-glacial deposit has 

 been urged long ago by various writers. Professor 

 Geikie regards it as stratigraphically contempor- 

 aneous with the peat and freshwater beds below the 

 lower diluvium of Western and Middle Germany, and 

 as having been laid down during the first Inter-glacial 



