KHOPALOCERA. 39 



Lake Tsana in Abyssinia also lias the sexes nearly alike. The inference 

 is obvious that the females in Madagascar and Abyssinia for some reason 

 do not stand in need of the protective disguises so elaborately worked 

 out for them in Southern and Western Africa. Probably some active 

 persecutors of this large pale type of Papilio are absent in those 

 countries, or may there have found some easier or more attractive 

 insect prey. In South Africa the handsome fly-catcher Tcldtrca cria- 

 tata has been seen by Mr. Mansel Weale to capture the male P. Cenea, 

 and he had reason to suspect a bird of an allied family and quite 

 similar habits, Dicnirus miisicus, to be another of this butterfly's 

 enemies. Insectivorous birds of both these genei'a are found in 

 Abyssinia — the very same species of Dicrurus is, I believe, a native of 

 that country — and also in Madagascar, but it is possible that circum- 

 stances may have led to their leaving Papilio Meropc and P. Meriones 

 unmolested. 



In considering these cases of mimicry, a difiiculty naturally 

 arises in perceiving how the initial stages of them could have been 

 of service to the mimickers. Taking, for instance, this very case 

 of Papilio Cenea and its allies, it may be asked of what possible 

 advantage to a large pale-yellow female such as the present P. 

 Meriones would be the merest beginning of darker colouring or of 

 shorter tails on the hind-wings, seeing that no enemy could for a 

 moment be led to mistake a specimen so very little modified for the 

 unpalatable Danais or Amauris ? Mr. Darwin has undoubtedly eluci- 

 dated this point by remarking {Descent of Man, i. p. 412) that " this 

 process " — the development of mimicry — " probably has never com- 

 menced with forms widely dissimilar in colour. But with two species 

 moderately like each other, the closest resemblance, if beneficial to either 

 form, could readily be thus gained ; and if the imitated form was 

 subsequently and gradually modified through sexual selection or any 

 other means, the imitating form would be led along by the same track, 

 and thus be modified to almost any extent, so that it might ultimately, 

 assume an appearance or colouring wholly unlike that of the other 

 members of the group to which it belonged." And Mr. Wallace has 

 further argued with much reason (Tropical Nature, &c., 1878, p. 190), 

 that there is no ground for supposing that, when the first steps towards 

 mimicry occurred, the Danaince were what they are now ; on the con- 

 trary, the considerable proportion still among them of species of what 

 may be termed ordinary butterfly colouring seems to indicate that, at 

 the period when they began to acquire those distasteful secretions 

 which protect them, their appearance and flight may not have been 

 nearly so peculiar as at present, but may have much more resembled 

 those of the unprotected families. At the same time, as they became 

 more unpalatable to enemies, it cannot be doubted that any peculiarity 

 about them would be preserved and emphasised by those enemies 

 avoiding the most distinguishable of them, and it is probably thus that 



