CHAPTER V. 



THE SIBERIAN MIGRATION. 



IN dealing with the British fauna in particular, I 

 have drawn attention to the fact that it is chiefly in 

 the south of England that we find fossil remains 

 of eastern species of mammals in recent geological 

 deposits. We can actually trace the remains of 

 these species and their course of migration across 

 part of the Continent towards Eastern Europe, and 

 as none of their bones have been discovered in the 

 southern or northern parts of our Continent, it must 

 be assumed that their home lay in Siberia, where 

 many still exist to the present day, and where 

 closely allied forms also are found. Some of these 

 Siberian migrants have remained in England and 

 on the Continent to the present day. Many have 

 become extinct. But the animals forming this 

 eastern migration did not all originate in Siberia, 

 though I have sometimes spoken of them collectively 

 as Siberian migrants. There must have been other 

 centres of dispersion of species in Europe. We know 

 that a very active centre of development at any rate 

 for land-mollusca lay in South-eastern Europe, either 

 in the Caucasus or in the Balkan peninsula, or more 



