found except the equally common
P. Pammon, a species already provided with two wives, and yet to whom we
shall be forced, I believe, to assign a third. On carefully examining P.
Romulus, I find that in all essential characters--the form and texture
of the wings, the length of the antennae, the spotting of the head and
thorax, and even the peculiar tints and shades with which it is
ornamented--it corresponds exactly with the other females of the Pammon
group; and though, from the peculiar marking of the fore wings, it has
at first sight a very different aspect, yet a closer examination shows
that every one of its markings could be produced by slight and almost
imperceptible modifications of the various allied forms. I fully
believe, therefore, that I shall be correct in placing P. Romulus as a
third Indian form of the female P. Pammon, corresponding to P.
Melanides, the third form of the Malayan P. Theseus. I may mention here
that the females of this group have a superficial resemblance to the
Polydorus group of Papilios, as shown by P. Theseus having been
considered to be the female of P. Antiphus, and by P. Romulus being
arranged next to P. Hector. There is no close affinity between these two
groups of Papilio, and I am disposed to believe that we have here a case
of mimicry, brought about by the same causes which Mr. Bates has so well
explained in his account of the Heliconidae, and which has led to the
singular exuberance of polymorphic forms in this and allied groups of
the genus Papilio. I shall have to devote a section of my essay to the
consideration of this subject.

The third example of polymorphism I have to bring forward is Papilio
Ormenus, which is closely allied to the well-known P. Erechtheus, of
Australia. The most common form of the female also resembles that of P.
Erechtheus; but a totally different-looking insect was found by myself
in the Aru Islands, and figured by Mr. Hewitson under the name of P.
Onesimus, which subsequent observation has convinced me is a second form
of the female of P. Ormenus. Comparison of this with Boisduval's
description of P. Amanga, a specimen of which from New Guinea is in the
Paris Museum, shows the latter to be a closely similar form; and two
other specimens were obtained by myself, one in the island of Goram and
the other in Waigiou, all evidently local modifications of the same
form. In each of these localities males and ordinary females of P.
Ormenus were also found.