204 HISTORY OF THE EUROPEAN FAUNA. 



confined to Arctic America and Greenland. The 

 Horse no longer occurs in Europe in the wild state, 

 and the Saiga Antelope (Saiga tartaricd) has retreated 

 to the Steppes of Eastern Europe and Western 

 Siberia. 



As we proceed more and more eastward across 

 Central Europe, we find that a larger and larger 

 percentage of the Siberian migrants have adopted 

 the new country as their permanent home, though in 

 France and Germany, as well as in Austria, we have 

 evidence that a great number of Siberian species, which 

 formerly lived there, have either become entirely 

 extinct, or have retreated towards the land of their 

 origin. There is a prevalent belief that these migrants 

 have taken refuge on the higher European mountain 

 ranges, but this idea is altogether erroneous, as will 

 be shown in the chapter dealing with the origin of the 

 Alpine fauna. 



One of the Jerboas (Alactaga jaculus) occurs fossil 

 as far west as Western Germany, but it is now con- 

 fined to Russia and Western Siberia. The Bobak 

 marmot (A rctoniys bobak\ which has a similar range 

 now, probably inhabited France in former times. 

 A Siberian species which has retreated but little is 

 the Hamster (Cricetus vulgaris). Its fossil remains 

 have been found in Central France, but it does not 

 now occur west of the Vosges Mountains. 



It appears, therefore, as if a wave of migration had 

 swept over Central Europe from east to west, that 

 those species which were able to adapt themselves to 



