170 Fhenomena of Variation and Geographical Distribution. 



peculiar tints and shades with which it is ornamented — it corresponds 

 exactly with the other females of the Pavimon 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 

 jnarkings could be produced by slight and almost imperceptible mod- 

 ifications 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, as shown by P. 

 Theseus having been considered to be the female of P. Antiphus, and 

 by P. Eomulus being arranged next to P. Hector. There is no close 

 affinity between these two groups of Papilio, and I am disposed to be- 

 lieve 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 Heli- 

 conidse, and which thus led to the singular exuberance of polymorphic 

 forms in this and alHed groups of the genus Papilio. I shall have to 

 devote a section of my paper to the consideration of this subject. 



The third example of polymorphism I have to bring forward is 

 Papilio Ormemis, Guer., which is closely allied to the well known P. 

 Drechtheus, Don., of Australia. The most common form of the female 

 also resembles that of P. Erechthexis ; but a totally different looking in- 

 sect was found by myself in the Aru Islands, and figured by Mr. Hew- 

 itson under the name of P. Onesimus, which subsequent observation 

 has convinced me is a second form of the female of P. OrmenuB. 

 Comparison of this with Boisduval's description of P. Amanga, a speci- 

 men of which from New Guinea is in the Paris Museum, shows the 

 latter to be a closely similar form; and two other specimens were ob- 

 tained 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. 

 So far there is no evidence that these light-colored insects are not 

 females of a distinct species, the males of which have not been discov- 

 ered. But two facts have convinced me that this is not the case. At 

 Dorey. in New Guinea, where males and ordinary females closely allied 

 to P. Ormenus occur (but which seem to me worthy of being separated 

 as a distinct species), I found one of these light-colored females closely 

 followed in her flight by three males, exactly in the same manner as 

 occurs (and, I believe, occurs only) with the sexes of the same species. 

 After watching them a considerable time, I captured the whole of 

 them, and became satisfied that I had discovered the true relations of 

 this anomalous form. The next year I had corroborative proof of the 



