The islands may therefore be divided into zoologically distinct groups 

 as follows : 



(1) The Palawan group, consisting of Palawan and the small islands 

 adjacent to it, Balabac, Cagayan Sulu, and the Cuyos and Calamianes 

 Islands. The birds of this group show a very strong Bornean element. 

 The line of demarcation between the Philippines, zoologically speaking, 

 and the Palawan Islands passes between Sibutu and the coast of Borneo 

 and extends thence northward through the Sulu Sea east of the Cuyos 

 group and through Mindoro Strait. 



(2) The central Philippines, comprising the Islands of Negros, Panay, 

 Guimaras, Masbate, and Ticao. They form a well-defined natural group, 

 although in the case of Masbate and Ticao there are indications of 

 immigration from Luzon. 



(3) Mindoro and some of the islands immediately adjacent to it, 

 including Semerara and doubtless also Ylin. 



(4) Luzon, Catanduanes, Marinduque, and Lubang. 



(5) Samar, Leyte, and Bohol. The Loriculus on Bohol proves to be 

 Loriculus worcesteri and not Loriculus apicalis, while the presence of 

 Orthotomus frontalis and Phabotrerom brevirostris among birds and of 

 Galeopithecus phiiippinensis and Tarsius spectrum among mammals 

 points unequivocally to the closest zoological relationship between Bohol 

 and Leyte. 



(6) Mindanao and the islands immediately adjacent to it form a group 

 by themselves. 



(7) Basilan must be separated from Mindanao on account of the fact 

 that it has a number of representative forms of Mindanao species and 

 lacks a number of species characteristic of Mindanao. 



(8) Bongao, Tawi Tawi, Lapac, Siasi, and Sulu form a well-marked 

 natural group, to which Sibutu must probably be added. 



(9) Tablas, Romblon, and Sibuyan show no evidence of having been 

 connected with any of the neighboring larger islands. They have a 

 number of peculiar species of birds, and Tablas and Romblon should 

 probably be classed together. 



(10) Cebu can not be regarded as one of the central Philippine group, 

 but must be classed by itself. 



(11) The Batanes Islands have a strong Formosan element among 

 their birds. It remains to be seen whether the Babuyanes Islands must 

 be grouped with them or must be considered as detached fragments of 

 northern Luzon. 



(12) Siquijor, Cagayancillo, and Cresta de Gallo are islands of recent 

 origin, and their bird faunae have been derived from stragglers from 

 neighboring islands. 



While these several groups are by no means zoologically equivalent, 

 each has its highly characteristic species and forms a fairly natural 

 division. 



