No. 591] 



NOTES AND LITERATURE 



189 



stable equilibrium between the mimetic and non-mimetic varie- 

 ties. Scanty historical data tend to show that the mimics were 

 as common fifty years ago, and probably a century and a half, as 

 to-day, so the author concludes "that in respect of mimetic re- 

 semblances natural selection does not exist for P. polytes in 

 Ceylon," or at least there is "no effect appreciable to the neces- 

 sarily rough method of estimation employed." 



The author next considers the evidence that the enemies of 

 butterflies could have played the part assigned to them by the 

 advocates of the mimicry theory. Predaceous insects evidently 

 pay no attention to warning colors ; certain lizards devour butter- 

 flies freely, but do not exercise any discrimination in the species 

 which they attack. Hence neither insects nor lizards can be sup- 

 posed to play any part in establishing a mimetic resemblance. 

 Birds destroy butterflies in considerable numbers, but 



Some of the most destructive appear to exercise no choice in the 

 species of butterfly attacked. They simply take what comes first and is 

 easiest to catch. 



Monkeys and baboons often eat butterflies. They show strong 

 likes or dislikes for certain species. The monkey may be re- 

 garded as "the ideal enemy for which advocates of the mimicry 

 theory have been searching — if only it could fly." The con- 

 clusion is reached that 



even a slight persecution directed with adequate discrimination will in 

 time bring about a marked result where the mimetic likeness is already 

 in existence. It is not impossible therefore that the establishing of such 

 a likeness may often be due more to the discrimination of the monkey 

 than to the mobility of the bird. 



In the final chapter on "Mimicry and Variation" the author 

 describes Carpenter's observations on the polymorphic mimic 

 Pseudacrcea eurytus, the four forms of which show an extraordi- 

 nary resemblance to acraeine "models" of the genus Planema. 

 These butterflies inhabit the shores of Victoria Nyanza in Cen- 

 tral Africa where the models are very abundant, the polymorphic 

 mimics less common but still numerous, and intermediates be- 

 tween the different types of mimic rare, but not unknown. On 

 Bugalla Island in the lake, on the contrary, the mimetic Pseuda- 

 craeas are very abundant, and their respective Planema models 

 relatively rare. Here intermediates between the varieties of 

 the polymorphic mimic occur in proportionately larger numbers 

 than on the mainland, owing as Dr. Carpenter believes to the 



