DISTRIBUTION OF THE BRITISH BUTTERFLIES. 277 



3. Lucina, Cratcegi, Rhamni, Polychloros, C-album, Betulce, 

 Pruni, W-album, Sibylla, Argiolus, Quercus, his, almost all feeding 

 on plants of a shrubby or arboreal nature, many of them requiring 

 cross-fertilisation. The insects, too, are partial to woodlands, 

 and possibly did not come in till the forest period. 



In conclusion, the facts or theories briefly alluded to in the 

 foregoing pages may be thus summarised : — 



1. Britain derived its butterfly fauna from continental Europe 

 in post-glacial times. 



2. The absence of certain English species from Scotland and 

 Ireland is not due to latitude, but possibl}' because the climate is 

 too " insular." 



3. The absence from Scotland of certain English and Irish 

 species is possibly due to temperature. 



4. The absence from Ireland of some English and Scottish 

 species appears not to be due to climate, but to the separation of 

 Ireland before these species could reach it. 



5. The most widely-distributed species are probably the most 

 ancient. 



6. The occurrence of species of butterflies in the outlying 

 islands does not of itself afford sufficient evidence for or against 

 their having reached the islands before the land connection was 

 severed. 



7. Though part of the fauna of Ireland reached it by way of 

 Scotland, some of the butterflies probably entered it by the 

 south. 



8. Arctic and alpine species probably colonised Britain before 

 species which are neither arctic nor alpine. 



9. Species whose larvse feed on low growing self- or wind- 

 fertilised plants would find their food-plants established before 

 those which feed on cross-fertilised or shrubby plants, and hence 

 be able to establish themselves sooner. 



10. Species combining the advantages of 8 and U were most 

 probably the first colonists. 



Aimat Lodge, Pertli, November, 1881. 



