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Show 222 MR. A. H. EVERETT ON THE ZOO-GEOGRAPHICAL [Apr. 16, pines. The significance of such a condition of things in the submarine geography of the area between Borneo and the Philippines is too well understood to render it necessary to enlarge upon it here; and if the settlement of the point at issue depended upon considerations of physical geography alone, it would probably be at once conceded by all that to include the Palawan group as an integral part of the Philippine sub-area is to draw a purely arbitrary line of delimitation somewhere through the Balabac straits and to the westward of Cagayan-Sulu and Sibutu, instead of adopting the natural boundary which soundings demonstrate to exist already in the Mindoro and Sibutu straits. But the geographical evidence for the connexion here advocated, though valuable in so far as it shows that a very slight elevation of the sea-bed would suffice now, and may have sufficed in the past, to join the Palawan group to Borneo, while one of considerable magnitude would be required to effect a junction with the Philippines, is not of convincing weight unless it can be shown that it is confirmed by the characteristic features of the Palawan fauna. For if we were to rely on the argument of physical geography alone, we should be confronted with the fact that Celebes might just as well be regarded as having been directly connected in recent geological time with Borneo, since that island also is apparently linked to the latter by a broad band of submarine bank, on which the soundings are everywhere, so far as is ascertained, less than 100 fathoms. And as this argument might be advanced, and this bank in the Straits of Macassar is a real difficulty, in view of the extreme dissimilarity of the faunas on either side of that strait, I may be permitted to digress for a moment before proceeding to examine the Palawan fauna, and to point out that in consequence of local circumstances, which are absent in the case of Palawan, this apparent evidence of a recent land-connexion between Borneo and Celebes is susceptible of being otherwise interpreted. The interpretation has been suggested by Mr. Wallace, who remarks1: " The southern portion of the Straits of Macassar is full of coral reefs, and a shallow sea of less than 100 fathoms extends from Borneo to within about 40 miles of the western promontory of Celebes; but farther north there is deep water close to the shore, and it seems probable that a deep channel extends quite through the straits, which have no doubt been much shallowed by the deposits from the great Bornean rivers as well as by those of Celebes itself. Southward, again, the chain of volcanic islands from Baly to Timor rise out of a deep ocean, the few soundings we possess showing depths of from 670 to 1300 fathoms almost close to their northern shores. W e seem justified therefore in concluding that Celebes is entirely surrounded by a deep sea, which has, however, become partially filled up by river-deposits, by volcanic upheaval, or by coral reefs. Such shallow seas, where they exist, may therefore be due to antiquity and isolation, instead of being indications of a former union with any of the surrounding islands." The rainfall in Borneo is enormous, and the country is largely made 1 ' Island Life,' p. 423. |