The most conspicuous instance of local modification of form, however, is exhibited in the island of Celebes, which in this respect, as in some others, stands alone and isolated in the whole archipelago. Almost every species of Papilio inhabiting Celebes has the wings of a peculiar shape, which distinguishes them at a glance from the allied species of every other island. This peculiarity consists, first, in the upper wings being generally more elongate and falcate; and secondly, in the costa or anterior margin being much more curved, and in most instances exhibiting near the base an abrupt bend or elbow, which in some species is very conspicuous. This peculiarity is visible, not only when the Celebesian species are compared with their small-sized allies of Java and Borneo, but also, and in an almost equal degree, when the large forms of Amboyna and the Moluccas are the objects of comparison, showing that this is quite a distinct phenomenon from the difference of size which has just been pointed out.
In the following Table I have arranged the chief Papilios of Celebes in the order in which they exhibit this characteristic form most prominently.
| Papilios of Celebes, having the wings falcate or with abruptly curved costa. | Closely allied Papilios of the surrounding islands, with less falcate wings and slightly curved costa. |
| 1. P. Gigon | P. Demolion (Java). |
| 2. P. Pamphylus | P. Jason (Sumatra). |
| 3. P. Milon | P. Sarpedon (Moluccas, Java). |
| 4. P. Agamemnon, var. | P. Agamemnon, var. (Borneo). |
| 5. P. Adamantius | P. Peranthus (Java). |
| 6. P. Ascalaphus | P. Deiphontes (Gilolo). |
| 7. P. Sataspes | P. Helenus (Java). |
| 8. P. Blumei | P. Brama (Sumatra). |
| 9. P. Androcles | P. Antiphates (Borneo). |
| 10. P. Rhesus | P. Aristæus (Moluccas). |
| 11. P. Theseus, var. (male) | P. Thesus (male) (Java). |
| 12. P. Codrus, var. | P. Codrus (Moluccas). |
| 13. P. Encelades | P. Leucothoë (Malacca). |
It thus appears that every species of Papilio exhibits this peculiar form in a greater or less degree, except one, P. Polyphontes, allied to P. Diphilus of India and P. Polydorus of the Moluccas. This fact I shall recur to again, as I think it helps us to understand something of the causes that may have brought about the phenomenon we are considering. Neither do the genera Ornithoptera and Leptocircus exhibit any traces of this peculiar form. In several other families of Butterflies this characteristic form reappears in a few species. In the Pieridæ the following species, all peculiar to Celebes, exhibit it distinctly:—
| 1. Pieris Eperia | compared | with | P. Coronis (Java). |
| 2. Thyca Zebuda | " | " | Thyca Descombesi (India). |
| 3. T. Rosenbergii | " | " | T. Hyparete (Java). |
| 4. Tachyris Hombronii | " | " | T. Lyncida. |
| 5. T. Lycaste | " | " | T. Lyncida. |
| 6. T. Zarinda | " | " | T. Nero (Malacca). |
| 7. T. Ithome | " | " | T. Nephele. |
| 8. Eronia tritæa | " | " | Eronia Valeria (Java). |
| 9. Iphias Glaucippe, var. | " | " | Iphias Glaucippe (Java). |
The species of Terias, one or two Pieris, and the genus Callidryas do not exhibit any perceptible change of form.
In the other families there are but few similar examples. The following are all that I can find in my collection:—
| Cethosia Æole | compared | with | Cethosia Biblis (Java). |
| Eurhinia megalonice | " | " | Eurhinia Polynice (Borneo). |
| Limenitis Limire | " | " | Limenitis Procris (Java). |
| Cynthia Arsinoë, var. | " | " | Cynthia Arsinoë (Java, Sumatra, Borneo) |
All these belong to the family of the Nymphalidæ. Many other genera of this family, as Diadema, Adolias, Charaxes, and Cyrestis, as well as the entire families of the Danaidæ, Satyridæ, Lycænidæ, and Hesperidæ, present no examples of this peculiar form of the upper wing in the Celebesian species.
Local variations of Colour.—In Amboyna and Ceram the female of the large and handsome Ornithoptera Helena has the large patch on the hind wings constantly of a pale dull ochre or buff colour, while in the scarcely distinguishable varieties from the adjacent islands of Bouru and New Guinea, it is of a golden yellow, hardly inferior in brilliancy to its colour in the male sex. The female of Ornithoptera Priamus (inhabiting Amboyna and Ceram exclusively) is of a pale dusky brown tint, while in all the allied species the same sex is nearly black with contrasted white markings. As a third example, the female of Papilio Ulysses has the blue colour obscured by dull and dusky tints, while in the closely allied species from the surrounding islands, the females are of almost as brilliant an azure blue as the males. A parallel case to this is the occurrence, in the small islands of Goram, Matabello, Ké, and Aru, of several distinct species of Euplœa and Diadema, having broad bands or patches of white, which do not exist in any of the allied species from the larger islands. These facts seem to indicate some local influence in modifying colour, as unintelligible and almost as remarkable as that which has resulted in the modifications of form previously described.