Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

152 THE MALAYAN PAPILIONID2E AS
by the discovery in the island of Batchian of a new
species allied to P. Ormenus, all the females of which,
either seen or captured by me, were of one form, and
much more closely resembling the abnormal lightcoloured females of P. Ormenus and P. Pandion than
the ordinary specimens of that sex. Every naturalist
will, I think, agree that this is strongly confirmative
of the supposition that both forms of female are of
one species; and when we consider, further, that in
four separate islands, in each of which I resided for
several months, the two forms of female were obtained
and only one form of male ever seen, and that about
the same time, M. Montrouzier in Woodlark Island,
at the other extremity of New Guinea (where he
resided several years, and must have obtained all the
large Lepidoptera of the island), obtained females
closely resembling mine, which, in despair at finding
no appropriate partners for them, he mates with a
widely different species-it becomes, I think, sufficiently evident this is another case of polymorphism
of the same nature as those already pointed out in
P. Pammon and P. Memnon. This species, however,
is not only dimorphic, but trimorphic; for, in the
island of Waigiou, I obtained a third female quite
distinct from either of the others, and in some degree
intermediate between the ordinary female and the
male. The specimen is particularly interesting to
those who believe, with Mr. Darwin, that extreme
difference of the sexes has been gradually produced
by what he terms sexual selection, since it may be