326 HISTORY OF THE EUROPEAN FAUNA. 



About sixty species of Erebia are known to 

 science, half of which are found in Europe, the 

 remainder in Siberia, the Himalayas, Arctic America, 

 Chili, Patagonia, South Africa, and Madagascar. 

 Though a few do range into these outlying regions 

 of the earth, Central Asia seems to lie near the centre 

 of distribution of the genus, and the probability is 

 that it also was its original home. Most of the 

 European species are high Alpine forms E. glacialis 

 being met with at a height of 10,000 feet and 

 these are generally quite peculiar to the Alps, 

 showing that their ancestors came from Asia at an 

 early date, probably by way of Asia Minor and 

 Greece. A few, as for instance E. lappona^ range 

 right across to the Altai' Mountains from the Alps, 

 and at least one E. melas is found in Greece. 

 Erebia migrations seem therefore to have taken 

 place by the Southern or Oriental route at different 

 geological periods. But some of the European 

 species which are more or less confined to the plain, 

 and are either absent from Switzerland or do not 

 reach the higher elevations, appear to me to have 

 come by the more direct northern or Siberian high- 

 way, at a still more recent period. These are Erebia 

 cethiops, medusa, ligea, and ambla. 



Only one species of the well-known Polar genus 

 (Eneis, viz. (E. aello, occurs in the Alps. It has 

 always been taken at very high elevations near the 

 verge of the snow-line on the most lofty parts 

 of the Simplon Pass, and other similar situations. 



