ALPINE RHOPALOCERA FAUNAS. 161 



dilleras crossing the Equator, and in the hxtter by the assist- 

 ance of the mountain ranges in Abyssinia and their continuance 

 southward through Zanzibar. Whatever differences these butter- 

 flies possess at the present day in order to enable them to be 

 placed in distinct genera from that of Erehia may be owing to 

 the change effected in post-glacial times by reason of the differ- 

 ences experienced in the organic environment. The only other 

 contingency I can discern is that these southern genera repre- 

 sent pre-glacial forms which existed in a cosmopolite condition, 

 both geographically and vertically, in both hemispheres, as I 

 have reason to suppose was the case with the genus (Enis 

 or its immediate stirps in pre-glacial times (see Entora. xxix. 

 345-349). 



Asia north of the Himalayas is probably the original homo 

 from whence the present alpine Khopalocera fauna of both 

 Europe and North America were indirectly or originally derived. 

 In the former continent, during Miocene times, a very different 

 fauna and flora existed to that which is the case at the present 

 day. This fauna and flora, which was exceedingly rich according 

 to the palreontological evidence, and partook of a subtropical 

 nature, was, during the succeeding Pliocene period, gradually 

 extirpated, and gave place to one which made its way from the 

 east, more in harmony with the less genial climatal conditions 

 which subsequently prevailed. 



It was during this epoch, or the early part of the Pleistocene 

 period which followed, that the present alpine Ehopalocera fauna 

 of Europe or their immediate stirps was primarily derived. 

 During the glacial period, as I have endeavoured to prove, the 

 greater part of them survived in the more hospitable regions in 

 the neighbourhood of the Mediterranean, the lowland forms 

 only seeking a shelter further south still, namely, in Asia Minor 

 and in Africa north of the Sahara Desert. It will therefore 

 appear that Hofmann is incorrect in supposing that the whole 

 of the post-glacial European Pihopalocera fauna have been 

 directly derived from regions situated outside its pale. Not 

 only am I supported in this contention from the fact of the 

 extensive paucity of the alpine Rhopalocera in the South of 

 Europe compared with the exceeding richness of that existing in 

 the Alps and the Pyrenees, but also from the researches of Sir 

 Joseph Hooker, who has proved the small amount of lateral 

 connection also between the different mountain ranges as regards 

 the derivation of their respective alpine floras. 



Birmingham, March 17th, 1897. 



