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Show 1889.] RELATIONSHIPS OF PALAWAN ISLAND. 221 indebted for our first acquaintance with the fauna of the islands question, has given formal expression, in a prominent scientific journal1, to the view that Palawan and Balabac should be considered as constituting, zoologically, a part of the Philippine Archipelago. Prof. Steere, having proceeded to divide the Philippine " Province" of the Indo-Malayan Sub-Region into six " Sub-Provinces," of which the sixth or Western Sub-Province "includes Balabac, Palawan, and perhaps the Calamianes," goes on to state that " this Sub-Province has evidently received a large portion of its fauna from North Borneo, through Balabac, at a comparatively recent date, and since its separation on the north from the rest of the Philippines, so that these genera have not flowed over into Mindoro and Luzon. In addition to these apparently late arrivals from Borneo, the Sub-Province possesses a large number of peculiarly Philippine birds and mammals, which show it to be an integral part of the province." So that it would seem from the above extract that, in Prof. Steere's opinion, the fundamental characteristics of the fauna of the Palawan group of islands are Philippine rather than Bornean, although there has been a comparatively more recent and very considerable invasion of Bornean forms; and the group is thus for the first time pronounced to be zoo-geographically, as it is politically, an integral portion of the Philippine sub-area. With this view I do not find myself able to concur, and it seems to me that such evidence as is available on the subject indicates rather that Palawan and the other islands mentioned by Prof. Steere have never been directly connected with any part of the Philippines since the former received their existing population, but that they have been almost certainly so connected with Borneo, or, more correctly perhaps, with a south-eastern extension of continental Asia, of which Borneo formed a part, It appears to me that it was from the Bornean side that these islands received their original fauna, and that the Philippine element is the foreign element and the one of comparatively recent advent. As it is very desirable that the natural relationship of the Palawan group should be placed on an established footing as soon as possible, I propose to offer briefly for consideration the grounds which seem to me to justify the definite inclusion of these islands in the western sub-area of the Indo-Malayan Sub-Region. A glance at the accompanying map of the Palawan group (Plate XXIII.) demonstrates at once that these islands, together with Cagayan-Sulu and Sibutu (which have been also looked upon as zoologically Philippine until recently), are all intimately connected with Northern Borneo by a very shallow submarine bank, the depth of the sea on which is generally less than 50 fathoms, and nowhere exceeds 100 fathoms continuously through the straits intervening between the China and Sulu seas. At the 100-fathom limit the bed of the ocean abruptly plunges down to depths ascending, in the Mindoro and Sibutu straits, 500 fathoms, and in the Sulu sea 1900 fathoms, thereby forming a profound gulf, which completely severs all the islands above mentioned from any connexion with the Philip- 1 'Nature,' Nov. 1888, pp. 37, 38. |