MELANISM IN LEPIDOPTERA. 151 



tenlrionale,' and Edwards' ' Butterflies of North America,' — 

 a fine illustrated book now in progress. A large amount of 

 information relating to North American Lepidoptera appears 

 every year in the publications of the nmnerous entomological 

 and other scientific societies now existing in the United 

 States and Canada. 



Zoological Department, Eoyal Dublin Society, 

 May, 1877. 



MELANISM IN LEPIDOPTERA 

 By Nicholas Cooke. 



Being a man of peace, it is out of my way even to have a 

 battle of words with Dr. Buchanan White on this subject ; 

 and I was much pleased on reading his able communication 

 in this month's ' Entomologist,' to find that he has rendered 

 it quite unnecessary. I agree with every word he has written 

 except, in spite of his positive assertion, that natural selection 

 is not sexual selection. 1 believe — and 1 think every person 

 of common sense believes — sexual selection is a most 

 natural selection. I also think he is wrong in saying that 

 " the occurrence of pale forms on chalk and other light- 

 coloured formations is brought about by natural selection, 

 not by the geological formation." If natural selection 

 exercises such a potent influence over the colours of Ze/?i- 

 doptera, we should have no dark species at all on the 

 chalk. Since my paper appeared I have bred two dark 

 varieties of a light-coloured species from the chalk. I 

 regret that I am not at liberty to mention the name of the 

 species ; the larvae were sent to me when young by a kind 

 friend, and I fed them on an oak tree in my garden in a leno 

 sleeve. I never saw or heard of a dark specimen of the 

 species before last year, and it puzzles me to account for 

 them, as other dark specimens have been procured from the 

 same wood on the chalk. Had it not been so, I should have 

 concluded that the soot on my tree was the cause of the 

 aberration ; but it is not so, for ii is evident there is a dark 

 race of this particular species existing on the chalk a long 

 distance from any manufacturing district. 



I have also lately become acquainted with the fact that 

 Tephrosia hiundularin oi the dark form, for which Dr. 



