v] SOME CRITICISMS 53 



come into contact with each other. Where one is 

 plentiful the other is not found. It has been suggested 

 that migratory birds may have come into play in 

 such cases. The bird learns in the low country that 

 D. plexippus is unpleasant, and when it pays a visit 

 to the hills it takes this experience with it and avoids 

 those females of the Fritillary which recall the un- 

 pleasant Danaine. 



Migratory birds have also been appealed to in 

 another case where the resembling species are even 

 further removed from one another than in the last 

 case. Hypolimnas misippus is common and widely 

 spread over Africa and Indo-Malaya, and the male 

 (PI. IV, fig. 8) bears a simple and conspicuous 

 pattern — a large white spot bordered with purple 

 on each of the very dark fore and hind wings. The 

 same pattern occurs in the males of two other Nym- 

 phalines allied to H. misippus, viz. Athyma punctata 

 and Limenitis albomaculata. The two species, however, 

 have a distribution quite distinct from that of H. 

 misippus, being found in China. It has nevertheless 

 been suggested by Professor Poulton 1 that the case 

 may yet be one of mimicry. According to his explana- 

 tion, H. misippus is unpalatable, the well-known 

 association of its female with Danais chrysippus being 

 an instance of Mullerian mimicry. Migratory birds 

 did the rest. Having had experience of H. misippus 

 in the south, on their arrival in China they spared 

 such specimens of Athyma punctata and Limenitis 



1 Essays on Evolution, 1908, p. 381. 



