Ivi European B utter fltes and Moths. 



real affinity, but which possess some special means of protection, in the advantage of which 

 the imitating species are supposed to share ; and the distribution of the various families and 

 genera over the earth, are all questions which, though only beginning to be investigated, 

 already throw great light on the laws by which a constant equilibrium is maintained among 

 the various competing forms of life on the earth, while it likewise serves to illustrate, to 

 some extent, its past history. 



Unfortunately, fossil butterflies are very rare, and their affinities are frequently doubtful ; 

 but they serve to confirm the results arrived at by the study of other groups, the remains 

 of which are better known, as to the affinity of the early European Fauna and Flora with 

 the present productions of tropical countries. 



This deficiency in fossil remains is compensated for, to a certain extent, by the study of 

 the distribution of existing species. It is now believed that the north of the Old World was the 

 spot where most of the principal forms of animal and vegetable life originated, and that those 

 which were not exterminated at the time of the Glacial Epoch were driven southwards. Some of 

 these returned to their old localities slowly after the retreat of the cold, while others, finding their 

 return prevented by insurmountable barriers, or by permanent changes of climate, only survive 

 at the present day in tropical countries, to which they were formerly strangers. Many Arctic 

 plants and insects are found at the summits of the Alps, and other high mountain ranges ; 

 and it is thought that they retreated up the mountains and towards the poles at the end of 

 the Glacial Period, and became isolated in these localities. 



The colours of larvse are also very interesting. Bright-coloured and conspicuous larvc-e 

 are rarely attacked by birds, and frequently feed on poisonous plants, and are therefore, 

 doubtless, themselves unwholesome ; but all larvae which are specially protected by their brown 

 or green colour, or by their resemblance to twigs, are greedily eaten by birds. Similar 

 observations may be made by almost any one ; and there are, no doubt, innumerable other 

 interesting and important discoveries to be made relative to Lepidopicra, which are at present 

 wholly unsuspected, but which may serve to throw a clearer light on many of the perplexing 

 scientific problems which we desire to unravel. 



