32 The Philippine Journal of Science 



are known from the Philippines, in contrast to one or, at most, 

 two that occur east of Wallace's Line and live only in Lombok 

 and Sumbawa, again indicating more-pronounced and longer- 

 continued land connections with the islands to the southwest 

 than with those to the south and southeast. 



10. No single line can be drawn, anywhere in Malaysia, that 

 is a true biogeographic boundary. With two stable areas delim- 

 ited by the Asiatic and Australian continental shelves and 

 an intermediate insular unstable region between these two stable 

 areas there must of necessity be an eastern and a western 

 boundary of the unstable area where it impinges on the stable 

 areas to the east and to the west. The western limits of the 

 unstable area are approximately denned by Wallace's Line, and 

 the eastern limits by Weber's Line. These two biogeographic 

 boundaries are primarily due to fundamental geologic conditions. 

 They may have approximately equal values but a much more 

 intensive biologic exploration of the entire region will be re- 

 quired before the essential data necessary to evaluate them 

 become available. Wallace's Line cannot be abandoned in favor 

 of Weber's Line nor vice versa. 



11. In Malaysia as a whole we find apparently two great 

 centers of origin and distribution, Sunda Land to the west and, 

 as Miss Gibbs 29 has already pointed out, New Guinea to the 

 east. To a large degree the fauna and flora of the islands in 

 the intermediate unstable area between Wallace's and Weber's 

 Lines are made up of infiltrations from the regions to the west 

 and to the east. From both regions there have been strong 

 migrations into the Philippines, one through the Sulu and Pala- 

 wan bridges from Sunda Land via Borneo, the other from Papua 

 through the Moluccas and Celebes. 



the phyto- 



