23,1 Merrill: Distribution of Dipterocarpaceae 6 



tioned above, one species of Vatica that occurs in Africa, and a 

 single species of Vateria that occurs in the Seychelles, the family 

 is confined to India, Ceylon, the Eastern Peninsula (one Shorea 

 in southeastern China and one Vatica in Hainan), the Sunda 

 Islands, the Philippines, the Moluccas, Celebes, and New Guinea. 

 The Sunda Islands taken as a whole, that is, Sumatra, Java, 

 Borneo, and the smaller intervening islands such as Bangka, 

 Billiton, and Lingga, present the most numerous species, total- 

 ing one hundred forty-four in eleven genera. Of this area 

 Borneo is specifically the richest in dipterocarps, presenting 

 eleven genera and one hundred three species. The total number 

 of species known from Sumatra is comparatively small, in all 

 probability due chiefly to the fact that the Sumatran flora is very 

 imperfectly known. The dipterocarp flora of Java is likewise 

 poor but this may be explained by the assumption that some 

 dipterocarps that may have existed in Java have been exter- 

 minated in comparatively recent times, that is, within the past 

 few centuries, through the almost complete destruction of the 

 primary forests throughout Java below an altitude of 1,200 

 meters Everywhere in Malaysia the destruction of the low- 

 altitude, primary forest means the destruction of the diptero- 

 carps The Eastern Peninsula, from Assam through Burma, 

 Siam, Indo-China to the southern part of the Malay Peninsula, 

 presents eleven genera and one hundred thirty-five species. 



The next richest area is the Philippines, with nine genera 

 and fifty species, our dipterocarps being distributed throughout 

 the Archipelago from Tawitawi in the Sulu Archipelago and 

 Palawan through Mindanao and the central part of the Archi- 

 pelago to northern Luzon and the Babuyan Islands. Five spe- 

 cies in five genera occur in the latter group, between Luzon and 

 Formosa. No representative reaches Formosa, and only a 

 single species of Shorea is known from the southwestern part of 

 Kwangtung Province, China, while a single species of Vatica 

 occurs in Hainan. 



India proper presents only thirteen species in six genera, in 

 striking contrast to this, the small island of Ceylon presents no 

 less than forty-seven species in ten genera, approximately the 

 same number of species and genera as occur in the entire Phil- 

 ippine Archipelago. The Ceylon dipterocarp flora is further 

 remarkable for its very definite endemism, the genus Doona with 

 twelve species, the genus Monoporandra with two species, and 

 the genus Stemonoporus with thirteen species being confined to 



