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

—XVIII.] NATURAL HISTORY OF CELEBES. 217all clear what effect the peculiar curvature of the wings hasin modifying flight.Another curious feature in the zoology of Celebes is alsoworthy of attention. I allude to the absence of several groupswhich are found on both sides of it, in the Indo-Malay islandsas well as in the Moluccas ; and which tlius seem to be unable,from some unknown cause, to obtain a footing in the interveningisland. In Birds we have the two families of Podargid?e andLaniadfe, which range over the whole Ai'cliipelago and intoAustralia, and which yet have no representative in Celebes.The genera Ceyx among Kingfishers, Criniger among Thrushes,Rhipidura among Flycatchers, 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 foundin Celebes. Among insects, the large genus of Rose-chafers,Lomaptera, is found in every country and island between Indiaand New Guinea, except Celebes. This unexpected absence ofmany groups, from one limited district in the very centre oftheir area of distribution, is a phenomenon not altogetherunique, but, I believe, nowhere so well marked as in this case ;and it certainly adds considerably to the strange character ofthis remarkable island.The anomalies and eccentricities in the natural history ofCelebes which I have endeavoured to sketch in this chapter, allpoint to an origin in a remote antiquity. The history ofextinct animals teaches us that their distribution in time andin space are strikingly similar. The rule is, that just as theproductions of adjacent areas usually resemble each otherclosely, so do the productions of successive periods in the samearea ; and as tlie productions of remote ai^eas generally differwidely, so do the productions of the same area at I'emote epochs.We are therefore led irresistibly to the conclusion, that changeof species, still more of generic and of family form, is a matterof time. But time may have led to a change of species in onecountry, while in another the forms have been more permanent,or the change may have gone on at an equal rate but in adifferent manner in both. In eitlier case the amount of individualityin the productions of a district, will be to some extent ameasure of the time that district has been isolated from thosethat surround it. Judged by this standard, Celebes must beone of tlie oldest parts of the Archipelago. It probably datesfrom a pei'iod not only anterior to that when Borneo, Java, andSumatra were separated from the continent, but from that stillmore remote epocli when tlie land that now constitutes tlicseislands had not risen above the ocean. Such an antiquity isnecessary to account for the number of animal forms itpossesses, which show no relation to those of India or Australia,but rather with those of Africa ; and we are led to speculateon the possibility of there having once existed a continent inthe Indian Ocean which might serve as a bridge to connect