6 The Philippine Journal of Science 1923 



Phyllitis dipterocarpoides from the Pliocene of Java, which is 

 compared to the living Dipterocarpus baudii Korth., KraiiseFs 

 Dipterocarpoxylon tobleri from the Miocene of Sumatra, and 

 also the latter's reference of Grewioxylon swedenborgii Schuster 

 from the East Indies to Dipterocarpoxylon, together with the 

 description of D. javanense Krausel from the Tertiary of Java. 

 He further notes that W oburnia porosa Stopes, from the English 

 Lower Green Sand (Lower Cretaceous) has been compared with 

 the Dipterocarpaceae, thus indicating that the family may have 

 had a long geologic history and a more-extended distribution in 

 the past. 



Fossil Dipterocarpaceae found in the Philippines and apper- 

 taining to the genera Anisoptera and Shorea, like those of the 

 Trinil formation in Java, are absolutely identical with species 

 now living in the Archipelago. The formation at Sagada, 

 Luzon, which has yielded a large number of leaf impressions, is 

 Pliocene. The Dipterocarpaceae represented here are Anisop- 

 tera thurifera Blume, Shorea guiso Blume, and S. polyspermy 

 Merr. Genera of other families, such as Calophyllum, Beil- 

 schmiedia, Diplodiscus, Cinnamomum, and Phoebe, are repre- 

 sented only by existing forms, and all species found are asso- 

 ciates of the dipterocarps in our low-altitude primary forests 

 of to-day. 



We now know enough of the geological history of the Dipter- 

 ocarpaceae to state definitely that this family was developed 

 and widely distributed in India and Malaysia in late Tertiary 

 times, and that it probably developed as a family in southern 

 Asia and in what is now western Malaysia when the Sunda 

 Islands were united with the Asiatic continent. It arose, per- 

 haps, in the early Tertiary or in the late Mesozoic. So far as 

 the Philippines is concerned, our Dipterocarpaceae reached the 

 Archipelago during the Pliocene or earlier, as, judging from the 

 nature of the fossil deposits known in Luzon, representatives 

 of this family were apparently dominant in the primary forests 

 of that time, as they are to-day. 



It is a peculiar biological character of this family that, with 

 almost no exception, the numerous species are essentially con- 

 fined to the primary forests. They do not thrive in the open 

 country and are never components of young secondary forests 

 or of forests that rapidly spring up in deforested areas that are 

 allowed to revert from cultivation where grass fires are not a 



