23, i Merrill: Distribution of Dipterocarpaceae 27 



Mindanao, Java, Sumatra, and the Malay Peninsula ; D. trinervis 

 Blume, from Palawan and Java ; Anisoptera curtisii Dyer, from 

 Luzon to Negros, Borneo, and the Malay Peninsula; Hopea 

 pierrei Hance, from Luzon to Mindanao, Borneo, Malay Penin- 

 sula, and Indo-China; Shorea balangeran Dyer, from Luzon to 

 Mindanao, Borneo, Bangka, and Billiton ; S. eximia Scheff ., from 

 Luzon to Mindanao, Borneo, Sumatra, and the Malay Peninsula ; 

 S. palosapis Merr., from Luzon to Mindanao and Borneo; S. 

 teysmanniana Dyer, from Luzon to Mindanao and Bangka; 

 and Isoptera borneensis Scheff., from the Zamboanga Peninsula 

 of Mindanao, Borneo, Bangka, and the Malay Peninsula. 



Only one dipterocarp, a species of Hopea, is known from the 

 Sulu Archipelago, this occurring on Tawitawi Island. This 

 might be interpreted to mean that our dipterocarps could not 

 have come over the Sulu bridge. There are a few islands in the 

 Sulu Archipelago on which dipterocarps might be expected, 

 notably Jolo and Tawitawi, but on Jolo the primary forest has 

 practically all been destroyed by man. The Sulu Archipelago 

 has moreover been raised and depressed, not once but several 

 times, so that it is only reasonable to suppose that its vegetation 

 has at times been partly or entirely' destroyed by natural causes. 



In Palawan we find but five recorded species of dipterocarps, 

 although future exploration may increase this number. They 

 are Dipterocarpus vernicifluus Blanco, D. grandiflorus Blanco, 

 D. trinervis Blume, Vatica obtusifolia Elm., and V. blancoana 

 Elm. Of these the first two occur throughout the Philippines 

 from northern Luzon to Mindanao, the first being supposedly 

 endemic, although possibly it should be reduced to D. gracilis 

 Blume, of Java ; the second extends to Borneo, Bangka, and the 

 Malay Peninsula. Dipterocarpus trinervis Blume is known only 

 from Palawan and Java ; Vatica blancoana Elm., only from Pala- 

 wan and Mindanao; and V. obtusifolia Elm. is confined to 

 Palawan. In Palawan we know of no representatives of the 

 genera Anisoptera, Balanocarpus, Hopea, Isoptera, Parashorea, 

 Pentacme, and Shorea; yet, all occur in the Philippines, many 

 being dominant, and all occur in western Malaysia. Can, then, 

 our dipterocarps have come in over the Palawan bridge? The 

 question cannot be answered definitely, but it is very clear that 

 most of our forms must have come in over one or both of these 

 Borneo-Philippine bridges, the Sulu to the south and the Palawan 

 to the north, on account of their paucity in the islands to the 

 south of the Philippines and in Java; they could scarcely have 

 come in from Java via Celebes. It is possible, even probable, 



