the prototype of V. UrticcB ? 7 



something more nearly allied to Y, C-alhion ; and some of the 

 species allied to the latter are very dark indeed. 



*' Lastly, as about half the species in the genua have the 

 wings far more deeply dentated and subcaudate than the 

 other half, whilst many gradations between the extremes of 

 these two types exist, it seems most natural to look for the 

 progenitor in a species which exhibits variation of form 

 in accordance with the season, so that one may account for 

 the prevalence of one type in one climate and of the other in 

 another ; and to regard two species of the same type as 

 descended one from the other, especially when these two 

 co-exist throughout Europe (or nearly so), seems to me to be 

 a su^Dposition in the highest degree improbable."] 



