OF THE MALAYAN REGION. 57 
is a male insect known which can be mated with it, except those of the Ormenus-form 
(which always occur in the same places), may, in conjunction with the observation already 
given of the companionship: of the two forms, be taken to prove that this is really a case 
of polymorphism. I believe also it will be found that these extreme departures from 
the typical form of a species are connected with mimetic resemblances and the safety of 
the individuals. We have already seen that the extreme forms of P. Memnon 9 and 
P. Pammon 9 respectively resemble other species which from their habits and abun- 
dance seem to have some peculiar immunity from danger. In this case also there is a 
resemblance to quite a different family of butterflies, the Morphidæ. In form, colora- 
tion, and general appearance these pale-coloured Papilios resemble species of the genus 
Drusilla; and the same genus is also imitated by other butterflies—one of these, Mela- 
nitis Agondas 9, having been actually confounded with Drusilla bioculata as the same 
species, so great is the resemblance. This fact of species of several genera imitating 
the Drusillas would indicate that they have some special immunities which make it 
advantageous to other insects to be mistaken for them; and their habits confirm this 
opinion. They have all a very similar style of dress, and fly very slowly, low down in 
damp woods, often settling on the ground or on rotten wood; and they are exceedingly 
abundant in individuals. Now these are the general characteristics of all groups which 
are the subjects of imitation ; and we may therefore presume, when we see forms depart- 
ing widely from the general appearance of their close relations, and resembling closely 
other groups with which they have no affinity, that what we must call accidental vari- 
ations have been accumulated and rendered definite by natural selection for the protec- 
tion and benefit of those forms. 
73. PaPrLIO0 Typeus, Felder. Tab. IV. figs. 3(¢), 2(2). 
P. Tydeus, Feld. Lep. Fragm. p. 52 (d). 
Female.—Upper side dusky brown; fore wings with the central portion below the 
cell nearly white; hind wings with the basal two-thirds white, with an irregular and 
obtusely dentated margin, and edged with ochre-yellow ; the rest black, with a submargi- 
nal row of seven broad yellowish lunules, and above those nearest the anal angle three 
irregular blue patches. 
Under side nearly as above; the white space on the upper wings is more extensive 
and better defined ; the marginal lunules are dilated so as to form a crenellated band, and 
the blue marks are increased to six or seven in number. Head and thorax dusky; 
abdomen yellowish. 
Hab. Batchian, Morty Island (Wall.). 
Remark.—The female, which seems to be of only one form in this species, is especially 
interesting as being allied to the pale-yellow form of P. Ormenus and P. Pandion. 
74. Parro Aprasrus, n. s. Tab. IV.fig.1(2). 
Male.—U pper side, like P. Ormenus d ; but has the band of the hind wings narrower, 
not crossing the cell, and more pointed towards the anal angle. 
VOL. XXY. : 
