MELANISM AND VARIAIloN IN LKPIDOPTERA. 129 



this direction have chiefly been amongst the European 

 Rhopalocera,* and seem to show that the specific differences 

 in the genital armature are much greater in some genera than 

 in others. When in very closely-allied species the structure is 

 found to be identical, it seems to be questionable whether the 

 species are really distinct. The value of the character in the 

 genus or family must, however, be taken into consideration 

 in forming a conclusion on that point. 

 Perth, April 4, 1877. 



ON MELANISM AND VARIATION IN LEPIDOPTERA. 



By W. Prest. 



Having for some years taken great interest in melanism 

 and variation in Lepidoptera, I should like to write a few 

 lines on the subject. I am of opinion that we shall have to 

 look still further than Mr. Nicholas Cooke seems to think for 

 the true cause of melanism and variation, for 1 have no doubt 

 that whatever the influence is which causes the one also 

 aff'ects the other. I do not think that either chemical fumes 

 or coal smoke can have any influence in this district of 

 Yorkshire, which is purely agricultural : we have very few tall 

 chimneys and no coal pits nor chemical works ; and yet we 

 meet with many cases of variation, and some of melanism, 

 in Lepidoptera. Take for instance the genus Acronycta : in 

 A. ligustri the form we usually find is suffused with dark 

 olive-green ; we very rarely see the white-crested form. I 

 took thirteen specimens of this species at sugar one season 

 some years ago, and of these, ten were this olive-green type, 

 with no white markings. Again, about Liverpool, the ento- 

 mologists take or breed A. menyanthidis of a very pale form ; 

 those we take near York are nearly black, and the light form 

 is very rare. A. rumicis also occurs nearly black at times 

 with us. 1 have taken A. leporina for nearly twenty years, 

 but never yet took the pale form near here ; ours are all the 

 variety Bradyporina. Chemical fumes and coal smoke 

 cannot, in these cases, be the influencing cause. How is it 

 that in the New Forest the female of Argynnis Paphia is 



* If Mr. Cooke cares to see the result of nay investigation, he will find it in 

 a forthcoming part of the Linnean Transactions. The paper is at present, I 

 believe, in the printer's hands. — F. B. W. 



