26 The Philippine Journal of Science 1923 



the Philippines, some with and some after (see p. 8) the 

 arrival of numerous other western Malaysian types ; at certain 

 times a limited number of Philippine types of dipterocarps and 

 other groups were enabled to migrate southward into Celebes, 

 Gilolo, the Moluccas, and New Guinea; and at the same time 

 numerous generic types from these regions, together with a 

 rather strong Australian element, were enabled to reach the 

 Philippines. 



The explanation of the fundamental differences in the geologic 

 history of eastern and western Malaysia, so clearly stated by 

 Molengraaff, enables us to give the reasons for the evident dif- 

 ferences between the floras and faunas of these two regions, and 

 to explain why the Philippine flora and fauna show definite 

 relationships with those of both eastern and western Malaysia ; 

 why the Australian element is so much stronger in the Philippine 

 flora than it is in that of western Malaysia ; and why the diptero- 

 carps and numerous other Malaysian types and, in general, the 

 Australian elements failed to reach Formosa, although many of 

 them extend to northern Luzon and some even into the Babuyan 

 and Batan Islands. Formosa is separated from the Philippines 

 by a very deep channel or trough, similar to those discussed by 

 Molengraaff as characteristic of eastern Malaysia. There is no 

 evidence of land connection between Luzon and Formosa since 

 early Tertiary times. 



I have already stated (p. 25) that the zoologists generally 

 derive the Palawan-Calamian fauna from Borneo, some claiming 

 that no connection can have existed between this group and the 

 Philippines proper since Palawan received its present fauna. It 

 is of some interest here to examine the Philippine distribution of 

 our dipterocarps. The larger islands characterized by the pres- 

 ence of numerous species are Luzon, Mindoro, Samar, Leyte, 

 Negros, Panay, Mindanao, and Balabac. But four species are 

 known from the Balabac-Palawan-Calamian group and but one 

 from the Sulu Archipelago. Thirty-nine of our fifty known 

 species, or 78 per cent, are endemic, the remainder occurring in 

 various parts of western Malaysia. Most of our endemic as well 

 as our extra-Philippine forms are of wide distribution within 

 the Archipelago, extending from northern Luzon to Mindanao 

 and Basilan. These are, of course, some local species. 



Of our nonendemic dipterocarps Dipterocarpus gracilis Blume 

 is recorded from Luzon, Mindoro, and Java; D. grandiflorus 

 Blanco, from Luzon to Mindanao, Palawan, Borneo, Bangka, 

 and the Malay Peninsula; D. hasseltii Blume, from Luzon to 



