187S.] 219 



If we do not consider tliis species an exception to the rule stated 

 by Mr. Darwin, then, according to this rule, as I understand it, half 

 the females and all the males in this species depart from the type. 

 Upon this point, Mr. Scudder remarks:* "If, on Darwin's theory, 

 " sometimes one-half, and sometimes three-quarters of a species has 

 " diverged from the type ; why does it never happen that only one- 

 " fourth of the species diverges ? This seems to be a very pertinent 

 "and damaging enquiry." 



It will be observed from my description of these two forms of 

 Erehla Medea, that the differences between them lie altogether on the 

 under-side of the wings, and chiefly on the hind wings. This is un- 

 usual and exceptional, according to Mr, Scudder, who states that : 

 " Whenever antigeny, colorational or structural, manifests itself in the 

 " wings of butterflies, the difference between the sexes almost invari- 

 " ably occurs upon the upper surface and generally upon the front 

 " wings only." 



As I have before stated, all the specimens of Erehia Medea with 

 which I am acquainted have been obtained from the same district. 

 I should therefore be glad to hear from those who have taken this 

 species in other localities in Great Britain, especially in Scotland, 

 whether, in their experience, the two forms of the females to which I 

 have called attention occur elsewhere, and if so, whether they are re- 

 presented in the same relative proportions. 



I have communicated these notes, not because I consider them 



of any intrinsic value, but in the hope that they may have the effect 



of directing increased attention, on the part of lepidopterists, to those 



colorational and structural peculiarities in various forms, the study of 



which cannot fail to throw some light on the question of the origin of 



species. 



Surbiton ITill, Surrey : 



6th February, 1878. 



NATURAL HISTORY OF BOARMIA ABIETARIA. 

 BY W. BUCKLER. 



I figured the larva of this species as long ago as 1SG3, but not the 

 less do I feel indebted to the llev. Bernard Smith for kindly sending 

 me eggs in July, 1.S7G, and thus giving me the opportunity to become 

 more thoroughly acquainted with all its changes. 



The food which is generally given for the larva is fir ; the examples 

 I had in 1863 chose birch in preference to fir ; Mr. Dorville, I remem- 

 ber, found a larva once on whortleberry, which he reared to maturity 



* Proc. Amer. Acad , ante cit, p. 153. 



