282 NATURAL HISTORY [chap. xvin. 



flight, and one much less under command. We might 

 snppose, therefore, that the butterflies which possess this 

 jjeculiar form were better able to escape pursuit. But 

 there seems no unusual abundance of insectivorons birds to 

 render this necessary ; and as we cannot believe tliat such 

 u curious peculiarity is without meaning, it seems probable 

 that it is tlie 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 ilammalia now 

 inhabiting it; and when the abundance of insectivorous 

 creatures, rendered some unusual means of escape a 

 necessity for tlie 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 gi'eat 

 strength and rapidity of flight. These were already suffi- 

 ciently protectetl from their enemies^ 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. 



Another curious feature in the zoology of Celebes is 

 also worthy of attention. I aUude to the absence of 

 several groups which are found on both sides of it, in the 

 Indo-ikday islands as well as in the Moluccas; and which 

 thus seem to be unable, from some unknown cause, to 

 obtain a footing in the intervening island. In Bii'ds we 

 have the two faniilies of Podargidie and Laniadai, which 

 range over the whole Archipelago and into Australia, and 

 which yet have no representative in Celebes. The genera 

 Ceyx among Kingflshers, Crinigei among Thrushes, lilnpi- 

 dni-a among Flycatchers, Calornis among Starlings, and 

 Iu7thrura among Finches, are all found in the Moluccas 

 as well as in Boi-neo and Java, — but not a single species 

 belonging to any one of them is found in Celebes, Among 

 insects, the large genus of liose-cbafers, Ijomaptera, is found 

 in every country and island between India and New Guinea, 

 except Celebes. This unexpected absence of many groups, 

 from one limited district" in the very centre of their area of 

 distribution, is a phenomenon not altogether unique, but, 

 1 believe, nowhere so well marked as in this case ; and it 



