78 THE SULU ISLANDS. [chap. 



and Philippine faunas here commingled. But at whatever point 

 to the south and west tliis junction with the mainland may have 

 occurred, it is most probable that it was of a more or less temporary 

 nature, — insufficient at least to permit the immigration of any but 

 a few species. There is a final hypothesis — perhaps more tenable 

 than either of the preceding — that the absence of Malayan forms 

 is due to subsidence of the islands at a period subsequent to their 

 separation from the continent. Be this as it may, however, the 

 fact remains that the Philippines are markedly insular in their 

 fauna and flora, and have been peopled to a considerable extent 

 from the Austro-Malayan region.^ 



Connecting then, as they do, two countries between which such 

 considerable differences exist, the Sulu Islands offered us most 

 interesting problems for solution. Previous to the ^dsit of the 

 Marchesa little or nothmg was known of the zoology of the 

 archipelago, although a few bu'ds had been brought home by Mr. 

 Burbidge, the well-known botanist. Our own ornithological 

 collection numbered considerably over two hundred specmiens and 

 comprised sixty-four species. This list is of course by no means 

 an exhaustive one, but, as will be seen, it is more than sufficient to 

 show the main source from wliich the bird-life of the archipelago 

 is derived. 



If from these sixty-four species we deduct those — for the most 

 part of wide distribution — which are common alike to Borneo and 

 the Philippines, we have thirty-eight species left. Of these two 

 were entirely new, and one (Carpophaga pickeringi) appears to be 

 confined to Sulu and a few small islands to the north of Borneo. 

 Tln'ee others {Dicrurus piectoralis, Ptilopus formosus, and Artamid.es 

 'pollens) are Celebean and Moluccan birds. Of the thirty-two 

 species remaining two only aie Bornean and /no less than thirty 

 Pliilippine. 



1 Anoa depressicornis — a most peculiar form of wild ox supposed to be confined 

 to Celebes — (see p. 211) is reported to be found also in Mindoro, but this fact has 

 not as yet been proved. 



