vn] THE CASE OF PAPILIO POLYTES 83 



heavy and lumbering up-and-down flight. One gets 

 the impression that all the wing surface is being used 

 instead of principally the fore wings as appears in 

 P. hector and P. aristolocMae. The difference is difficult 

 to put mto words, but owing to these pecuharities ^f 

 flight the eye has no difficulty in distinguishing betj?§,en 

 model and mimic even at a distance of 40 to 5Q, yards. 

 Moreover, colour ngedllot enter into th^jnatter-at-all. 

 It is even easier to distinguish model from mimic when 

 flying against a bright background, as for instance when 

 the insect is between the observer" and a" sunlit sky, 

 than it is to do so'by Teflected light; I have myself 

 spent many days in doing little else but chasing polytes 

 at Trincomalee where it was flying in company with 

 P. hector, but I was never once Imred into chasing the 

 model in mistake for the mimic. _^y experience was 

 that whether at rest or flying the species are perfectly 

 distinct, anffTTfiSii it difficult to imagine that a bird 

 whose living depended in part upon its ability to dis- 

 criminate~15eiwien the different forin^woi^ be likely 

 -to^be misled. '<^6ftainly it would not be if its pow^s 

 of discrimination were equal to those of an ordinary 

 civilised man. If the bird were unable to distinguish 

 between say the A form of female and P. aristolocMae 

 I think that it would be still less likely to distingmsh 

 between the same A form and the male or the M form 

 of female. For my experience^sras^ th^ jLt_jJittle 

 distanceone 3ail4^ easily'' £onf use J^ A form of 

 ^oZ^es with the male. Except when one was quite 

 ^Jose^theTfed on tEe A form was apt to be lost, the 



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