Of Celebes. 286 



to consider that the dispersion and migration of insects is 

 much more easily affected than that of mammals even of birds. 

 They are much more likely to be carried away by violent 

 winds ; their eggs may be carried on leaves either by storms 

 of wind or by floating trees, and their larvse and pupae, often 

 buried in trunks of trees or inclosed in waterproof cocoons, 

 may be floated for days or weeks uninjured over the ocean. 

 These facilities of distribution tend to assimilate the produc- 

 tions of adjacent lauds in two ways : first, by direct mutual 

 interchange of species; and secondly by repeated immigra- 

 tions of fi-esh individuals of a species common to other isl- 

 ands, which by intercrossing, tend to obliterate the changes 

 of form and color, which difEerences of conditions might other- 

 wise produce. Bearing these facts in mind, we shall find that 

 the individuality of the insects of Celebes is even greater than 

 we have any reason to expect. 



For the purpose of insuring accuracy in comparisons with 

 other islands, I shall confine myself to those groups which are 

 best known, or which I have myself carefully studied. Be- 

 ginning with the Papilionidse, or swallow-tailed butterflies, 

 Celebes possesses 24 species, of which the large number of 18 

 are not found in any other island. If we compare this with 

 Borneo, which out of 29 species has only two not found else- 

 where, the difference is as striking as any thing can be. In 

 the family of the Pierid^e, or white butterflies, the difference 

 is not quite so great, owing perhaps to the more wandering 

 habits of the group ; but it is still very remarkable. Out of 

 30 species inhabiting Celebes, 19 are peculiar, while Java 

 (from which more species are known than from Sumatra or 

 Borneo), out of 37 species has only 13 peculiar. The Dana- 

 idae are large, but weak-flying butterflies, which frequent for- 

 ests and gardens, and are plainly but often very richly color- 

 ed. Of these my own collection contains 16 species from 

 Celebes and 15 from Borneo ; but whereas no less than 14 are 

 confined to the former island, only two are peculiar to the lat- 

 ter. The Nymphalidse are a very extensive group, of gener- 

 ally strong-winged and very bright-colored butterflies, very 

 abundant in the tropics, and represented in our own country 

 by our pritillaries, our Vanessas, and our Purple Emperor. 

 Some months ago I drew up a list of the Eastern species of 



