XLIV 



Now as regards the Satyridae, on proceeding to a general consideration of 

 this family, two of the subjects, already referred to when treating of the Danaidae, 

 come to the front, in respect of which clearer ideas are required than usually 

 obtain in order to understand the phenomena which present themselves so 

 prominently in the butterflies of this family. First, that of colour evolution 

 which in this family plays so important a role and frequently produces colour 

 phenomena which, without a knowledge of this process, are inexplicable. Secondly, 

 the mistaken notion, already referred to, concerning the alleged seasonal varieties 

 which, in judging the differences existing between butterflies of the same species 

 in this family, has attained a truly fearful extent. 



We will first consider colour evolution. There are surely few things which 

 to every lepidopterologist, who is concerned with the study of the Indo- 

 Australian fauna, appear equally striking as the great variation in colour and 

 marking of the wings of Cyllo Leda L., especially on their under side. This 

 is not, indeed, confined to this species, since in Kallima paralecta Horsf, 

 for instance, the colour of the underside of the wings also offers much variety, 

 but in the former it is much more pronounced and on account of the common 

 occurrence of this butterfly this rivets the attention more. No other phenom- 

 enon which presents itself in connection with the subject, I venture to say, 

 hcis been less capable of interpretation. Of course there has been no lack of 

 phrases concerning the influence of the environment etc. in this connection but, 

 although it is not impossible that this may exercise some influence, it is by 

 no means certain that this is so ; in any case this assumption does not really 

 help us to an understanding and the theory of mimicry enables us least of all 

 to explain the origin of so many differences. The fact that such resemblance 

 in colour with its environment may sometimes afford a butterfly some protection 

 against its enemies, in so far as these pursue them by sight only, may be 

 taken for granted but it does not explain in what manner this arises. With 

 the aid of the theory of colour evolution, however, this truly very intricate 

 phenomenon may be elucidated, and, at least at present, exclusively by means 

 of it, which consequently constitutes a very powerful argument for the correctness 

 of this theor}'. The value of a theory can, indeed, be gauged only by what 

 it enables us to elucidate. 



When treating of this species in its proper place I will fully explain my 

 meaning in this connection, but since this has a general bearing on the value 

 of the theory in question I have thought it useful to refer to it here. 



An explanation of many other phenomena, which are particularly conspic- 

 uous in the Satyridae, must also be looked for in the theory alluded to. 

 Midway between the dark-coloured species of a genus so typical of this family. 



