THE CLOUDED YELLOW BUTTERFLY. 118 



are two forms of females, the difference between them 

 being much greater than that between Edusa and 

 Helwe. One possesses two tail-like appendages on 

 the hind wings, of which neither the male nor the 

 other female possesses the slightest vestige. The 

 colours too are different. The tailed variety how- 

 ever closely resembles the normal female of an allied 

 species, P. Coon, so that we have here a case of 

 mimicry. In the north of India P. Coon is replaced 

 by another species P. Doubledayi, and P. Memnon is 

 replaced by an allied species P. Androgeus. And 

 here curiously enough there are two female forms of 

 the latter, one of which mimics the female of P. 

 Donbledayi. Mr. Wallace offers the following in ex- 

 planation : " The butterflies imitated belong to a 

 section which from some cause or other are not 

 attacked by birds ; and by so closely resembling these 

 in form and colour the female of Memnon and its 

 ally also escape persecution." If so, then I should 

 imagine that the tailed variety will prove permanent, 

 while the other will die out. All three forms of the 

 male and the two females are produced from eggs of 

 either female. Mr. Wallace's explanation serves to 

 show theoretically how one form may replace another. 

 Well now, in the case of Edusa, have we here an ex- 

 ample before our eyes of a transmutation of species 

 or of form gradually going on ? Will this change 

 some day extend to the males, and will there be by 

 and by a totally distinct species having a white 

 ground colour ? or will the change be confined to the 

 females, the old form of which will die out ? In 

 connection with this again, does the white colour of 

 Helice afford it any protection against enemies ? 



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