Travel Reference
In-Depth Information
elongated wing of Tachyris zarinda, a native of Celebes, compared with the much shorter
wing of Tachyris nero, a very closely allied species found in all the western islands. The dif-
ference of form is in each case sufficiently obvious, but when the insects themselves are
compared it is much more striking than in these partial outlines.
From the analogy of birds, we should suppose that the pointed wing gave increased rapid-
ity of flight, since it is a character of terns, swallows, falcons, and of the swift-flying pi-
geons. A short and rounded wing, on the other hand, always accompanies a more feeble or
more laborious flight, and one much less under command. We might suppose, therefore, that
the butterflies which possess this peculiar form were better able to escape pursuit. But there
seems no unusual abundance of insectivorous birds to render this necessary; and as we can-
not believe that such a curious peculiarity is without meaning, it seems probable that it is the
result of a former condition of things, when the island possessed a much richer fauna, the
relics of which we see in the isolated birds and Mammalia now inhabiting it; and when the
abundance of insectivorous creatures, rendered some unusual means of escape a necessity
for the large-winged and showy butterflies. It is some confirmation of this view, that neither
the very small nor the very obscurely coloured groups of butterflies have elongated wings,
nor is any modification perceptible in those strong-winged groups which already possess
great strength and rapidity of flight. These were already sufficiently protected from their en-
emies, and did not require increased power of escaping from them. It is not at all clear, what
effect the peculiar curvature of the wings has, in modifying flight.
