23, i Merrill: Distribution of Dipterocarpaceae 23 



Passage would also greatly restrict the passage of both plants 

 and animals, and it is safe to assume that such swift currents 

 have existed since the Lombok Passage was formed. 



In connection with the paucity of Dipterocarpaceae known 

 from eastern Malaysia and the possibility that the number may 

 be increased by further exploration, Diels has already expressed 

 his opinion regarding New Guinea. No species is known from 

 Gilolo, where a few at least are to be expected. Only five are 

 known from all of Celebes, and in view of Doctor S. H. Koor- 

 ders's extensive botanical explorations in northern Celebes (Mi- 

 nahassa) we can hardly expect many additional species in this 

 part of Celebes. Doctor Koorders collected in Minahassa pri- 

 marily as a forester for nearly five months, and as a forester 

 he certainly would not have overlooked the economically import- 

 ant dipterocarps ; his entire collection from Minahassa in north- 

 ern Celebes, comprising some 3,500 numbers, presents only a 

 single species of Dipterocarpaceae, Shorea koordersii Brandis. 

 It would seem then that we are not justified in expecting 

 numerous additions to the dipterocarp flora of eastern Malaysia 

 as botanical exploration progresses, in spite of the fact that the 

 flora of the entire region is very imperfectly known, although 

 it is about as well known, comparatively speaking, as is that 

 of Sumatra and Borneo. 



We have seen then that the dipterocarps are very strongly 

 represented in western Malaysia, that is, "Sunda Land," the 

 Malay Peninsula, Sumatra, Java, and Borneo; very poorly rep- 

 resented in eastern Malaysia, Celebes, the Moluccas, Gilolo, and 

 New Guinea; and fairly well represented in the Philippines, by 

 nine genera and fifty species, the great trees of this family being 

 dominant in the primary forests of our Archipelago at low 

 altitudes. Therefore, it will be seen that the Philippines are 

 intermediate between eastern and western Malaysia in dip- 

 terocarp representation. 



What is the case in reference to other families of plants? It 

 has been known for over twenty years that the Philippine flora 

 presents strong Celebesian and Moluccan alliances, and as explo- 

 ration has progressed Papuan, New Caledonian, and Australian 

 elements have become more and more evident. At the same 

 time, there are distinct evidences of definite relationships with 

 western Malaysia or the Sunda Islands, as indicated by the gen- 

 era of Dipterocarpaceae alone. Of the twelve genera of this 

 family found in the Malay Peninsula and the Sunda Islands nine 

 extend to the Philippines, as against four that extend to eastern 



