152 THE MALAYAN PAPILIONIDJE 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 light- 

 coloured 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, suffi- 

 ciently 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 



