266 HISTORY OF THE EUROPEAN FAUNA. 



has spread some species to the Himalayas, and 

 a few to Europe and North America. But these 

 migrations are not of very recent date. Parnassius 

 no doubt arrived accompanied by a large number 

 of other Central Asiatic mountain insects and 

 plants. I shall refer to the latter again when 

 dealing with the origin of the Alpine fauna, but 

 meanwhile it might be mentioned that the famous 

 Swiss "Edelweiss" (Leontopodium alpinuni), which 

 we are accustomed to regard as a typical Alpine 

 plant, is certainly of Asiatic origin. In some parts 

 of Southern Siberia it is one of the common meadow- 

 flowers, and ranges from there south into Kashmere, 

 but not northward. Like the Apollo, it does not 

 occur in Scandinavia or Northern Siberia. Both 

 plant and insect evidently migrated from Central 

 Asia, directly westward along the southern border of 

 the sea, which extended from that region as far as 

 the European Alps in early Tertiary times. At that 

 time the Caucasus was possibly still connected with 

 the Balkan Mountains, across what is now the Black 

 Sea, and that may have been the highway on which 

 they travelled west. 



Some of the Clouded-Yellows butterflies apper- 

 taining to the genus Colias formed part of the 

 Oriental migration. The genus is undoubtedly of 

 Asiatic origin, and while many of the species have 

 turned northward, ranging across Siberia and North 

 America, others have taken a southern and westward 

 turn and thus reached Europe. We have two 



