Another curious feature in the zoology of Celebes is also worthy of attention. I allude to the absence of several groups which are found on both sides of it, in the Indo-Malay 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 Birds we have the two families of Podargidae and Laniadae, which range over the whole Archipelago and into Australia, and which yet have no representative in Celebes. The genera Ceyx among Kingfishers, Criniger among Thrushes, Rhipidura among Flycatchers, Calornis among Starlings, and Erythrura among Finches, are all found in the Moluccas as well as in Borneo and Java--but not a single species belonging to any one of them is found in Celebes. Among insects, the large genus of Rose-chafers, Lomaptera, 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, I believe, nowhere so well marked as in this case; and it certainly adds considerably to the strange character of this remarkable island.
The anomalies and eccentricities in the natural history of Celebes which I have endeavoured to sketch in this chapter, all point to an origin in a remote antiquity. The history of extinct animals teaches us that their distribution in time and in space are strikingly similar. The rule is, that just as the productions of adjacent areas usually resemble each other closely, so do the productions of successive periods in the same area; and as the productions of remote areas generally differ widely, so do the productions of the same area at remote epochs. We are therefore led irresistibly to the conclusion, that change of species, still more of generic and of family form, is a matter of time. But time may have led to a change of species in one country, while in another the forms have been more permanent, or the change may have gone on at an equal rate but in a different manner in both.
In either case, the amount of individuality in the productions of a district will be to some extent a measure of the time that a district has been isolated from those that surround it. Judged by this standard, Celebes must be one of the oldest parts of the Archipelago. It probably dates from a period not only anterior to that when Borneo, Java, and Sumatra were separated from the continent, but from that still more remote epoch when the land that now constitutes these islands had not risen above the ocean.
Such an antiquity is necessary, to account for the number of animal forms it possesses, which show no relation to those of India or Australia, but rather with those of Africa; and we are led to speculate on the possibility of there having once existed a continent in the Indian Ocean which might serve as a bridge to connect these distant countries. Now it is a curious fact, that the existence of such a land has been already thought necessary, to account for the distribution of the curious Quadrumana forming the family of the Lemurs. These have their metropolis in Madagascar, but are found also in Africa, in Ceylon, in the peninsula of India, and in the Malay Archipelago as far as Celebes, which is its furthest eastern limit. Dr. Sclater has proposed for the hypothetical continent connecting these distant points, and whose former existence is indicated by the Mascarene islands and the Maldive coral group, the name of Lemuria. Whether or not we believe in its existence in the exact form here indicated, the student of geographical distribution must see in the extraordinary and isolated productions of Celebes, proof of the former existence of some continent from whence the ancestors of these creatures, and of many other intermediate forms, could have been derived.
In this short sketch of the most striking peculiarities of the Natural History of Celebes, I have been obliged to enter much into details that I fear will have been uninteresting to the general reader, but unless I had done so, my exposition would have lost much of its force and value. It is by these details alone that I have been able to prove the unusual features that Celebes presents to us. Situated in the very midst of an Archipelago, and closely hemmed in on every side by islands teeming with varied forms of life, its productions have yet a surprising amount of individuality. While it is poor in the actual number of its species, it is yet wonderfully rich in peculiar forms, many of which are singular or beautiful, and are in some cases absolutely unique upon the globe. We behold here the curious phenomenon of groups of insects changing their outline in a similar manner when compared with those of surrounding islands, suggesting some common cause which never seems to have acted elsewhere in exactly the same way. Celebes, therefore, presents us with a most striking example of the interest that attaches to the study of the geographical distribution of animals. We can see that their present distribution upon the globe is the result of all the more recent changes the earth's surface has undergone; and, by a careful study of the phenomena, we are sometimes able to deduce approximately what those past changes must have been in order to produce the distribution we find to exist. In the comparatively simple case of the Timor group, we were able to deduce these changes with some approach to certainty. In the much more complicated case of Celebes, we can only indicate their general nature, since we now see the result, not of any single or recent change only, but of a whole series of the later revolutions which have resulted in the present distribution of land in the Eastern Hemisphere.
