EHOPALOCERA. 
39 
Lake Tsana in Abyssinia also has 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 Tcliitrca cris- 
tata has been seen by Mr. Mansel Weale to capture the male F. Cenea, 
and he had reason to suspect a bird of an allied family and quite 
similar habits, Dicrurus mtosicus, to be another of this butterfly's 
enemies. Insectivorous birds of both these genera 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 Iferope and P. Meriones 
unmolested. 
In considering these cases of mimicry, a difficulty 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 Cenca 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. 4 1 2) 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 
