The Malay archipelago : the land of the orang-utan ... - Wallace Online

XVIII.] NATURAL HISTORY OF CELEBES. 215These large arid well-known families well represent thegeneral character of the zoology of Celebes ; and they showthat this island is really one of the most isolated joortions ofthe Archipelago, although situated in its very centre.But the insects of Celebes present us with other phenomenamore curious and more difficult to explain than their specificindividuality. The butterflies of that island ai'e in many casescharacterized by a peculiarity of outline, which distinguishesthem at a glance from those of any other part of the world.It is most strongly manifested in the Papilios and the Pierida?,and consists in tlie fore-wings being either strongly curved orabruptly bent near the base, or in the extremity being elongatedand often somewhat hooked. Out of the 14 species of Papilioin Celebes, 13 exhibit this peculiarity in a greater or less degree,when compared with the most nearly allied species of thesurrounding islands. Ten species of Pieridse have the samecharacter, and in four or five of the Nymphalidse it is also verydistinctly marked. In almost every case the species found inCelebes are much larger than those of the islands westward,and at least equal to those of the Moluccas, or even larger.The difierence of form is however the most remarkable feature,as it is altogether a new thing for a whole set of species in onecountry to clifier in exactly the same way from the correspondingsets in all the surrounding countries ; and it is so well marked,that without looking at the details of colouring, most CelebesPajDilios and many Pieridse can be at once distinguished fromthose of other islands by their form alone.The outside figure of each pair here given shows the exactsize and form of the fore-wing in a buttei'fly of Celebes, whilethe inner one represents the most closely allied species fromone of the adjacent islands. Figure 1 shows the stronglycurved margin of the Celebes species, Papilio gigon, comparedwith the much straighter margin of Papilio demolion fromSingapore and Java. Figure 2 shows the abruj^t bend overthe base of the wing in Papilio miletus of Celebes comjDaredwith the slight curvature in the common Papilio sarjoedon,which has almost exactly the same form from India to NewGuinea and Australia. Figure 3 shows the elongated wing ofTachyris zarinda, a native of Celebes, compared with the muchshorter wing of Tachyris nero, a very closely allied species foundin all the western islands. The diSerence of form is in each casesufficiently obvious, but when the insects themselves are comparedit is much more striking than in these partial outlines.From the analogy of birds, we should suppose that the pointedwing gave increased rapidity of flight, since it is a character ofterns, swallows, falcons, and of the swift-flying pigeons. Ashort and rounded wing, on the other hand, always accompaniesa more feeble or more laborious flight, and one much less undercommand. We might suppose, therefore, that the butterflieswhich possess this peculiar form were better able to escape