OF THE MALAYAN REGION. 7 



not only has no male specimen of P. Folytes yet been found, but the female {Polytes) has 

 never yet been found in localities to which the male (Pammon) does not extend. In this 

 case, as in the last, distinct species, local forms, and dimorphic specimens have been con- 

 founded under the common appellation of varieties. 



But, besides the true P. Folytes, there are several allied forms of females to be con- 

 sidered, namely, P. Theseus, Cr., P. Melanides, De Haan, P. Myros, G. R. G., and 

 P. Bomultis, L. The dark female figured by Cramer as P. Theseiis seems to be the com- 

 mon and perhaps the only form in Sumatra, whereas in Java, Borneo, and Timor, along 

 with males quite identical with those of Sumatra, occur females of the Folytes form, 

 although a single specimen of the true P. Theseus, Cr., taken at Lombock would seem to 

 show that the two forms do occur together. In the allied species found in the Philippine 

 Islands (P. Alphenor, Cr., P. Ledebonria, Eschsch., S P. Elyros, G. E. G.) forms corre- 

 sponding to these extremes occur along with a number of intermediate varieties, as shown 

 by a fine series in the British Museum. We have here an indication of how dimorphism 

 may be produced ; for let the extreme Philippine forms be better suited to their condi- 

 tions of existence than the intermediate connecting links, and the latter will gradually 

 die out, leaving two distinct forms of the same insect, each adapted to some special con- 

 ditions. As these conditions are sure to vary in different districts, it will often happen, 

 as in Sumatra and Java, that the one form will predominate in the one island, the other 

 in the adjacent one. In the island of Borneo there seems to be a third form ; for P. Mela- 

 nides, De Haan, evidently belongs to this group, and has aU the chief characteristics of 

 P. Theseus, with a modified coloration of the hind wings. I now come to an insect 

 which, if I am correct, offers one of the most interesting cases of variation yet adduced. 

 FapiUo Bomuliis, L., a butterfly found over a large part of India and Ceylon, and not 

 uncommon in collections, has always been considered a true and independent species, 

 and no suspicions have been expressed regarding it. But a male of this form does not, I 

 believe, exist. I have examined the fine series in the British Museum, in the East India 

 Company's Museum, in the Hope Museum at Oxford, in Mr. Hewitson's and several other 

 private collections, and can find nothing but females ; and for this common butterfly no 

 male partner can be found except the equally common P. Fammon, 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. Bomulus, 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 Fammon 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. Bomulus as a third Indian form of the female P. Fammon, corre- 

 sponding 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 Folydorm 

 group, as sho^vn by P. Theseus having been considered to be the female of P. Antiphus, 

 and by P. Bomulus being arranged next to P. Hector. There is no close affinity between 



