Malaysian Phytogeography and Polynesian Flora 249 



The intermigrations of the early angiosperms in what is now 

 tropical Asia and Malaysia doubtless took place at a time when 

 the continental area extended far to the south, probably in the 

 late Cretaceous and early Tertiary, and this is the period when 

 the more widely dispersed Asiatic types, or the ancestors of cer- 

 tain Asiatic types now found in New Guinea, extended their 

 ranges. There seems to be little or no evidence of direct Asia- 

 New Guinea land connections since the early Tertiary. 



The evidence is that, in later times, there were an eastern and 

 a western route of intermigration as between Asia and Malaysia, 

 the former from southeastern Asia and Formosa south through 

 the Philippines at least as far as Celebes, and the latter from India 

 through Burma and the Malay Peninsula to Java, Sumatra, and 

 Borneo, with apparently a secondary paralleling line through 

 what is now the Andaman Islands to Sumatra and perhaps Java. 

 These routes were doubtless in operation at a relatively early 

 time, probably in the Tertiary, so far as the ancestors of our 

 modern flora were concerned. At a later period, particularly 

 from the Pliocene-Pleistocene into the Recent, there must have 

 been a very active interchange of plants between Asia and west- 

 ern Malaysia, when the Sunda Islands (Java, Sumatra, and Bor- 

 neo) and the Palawan-Calamian group in the Philippines were 

 at times definitely a part of the Asiatic continent. 



The Malay Archipelago lies wholly within the tropics. This 

 great equatorial group of islands extends from the northwest to 

 the southeast, from northern Sumatra to eastern New Guinea, a 

 distance of about 4000 miles. Throughout this vast region the 

 climatic conditions are essentially uniform; for the most part, 

 precipitation is ample and, in certain areas, even extreme, and 

 the average temperatures at equal altitudes are strikingly uni- 

 form. In the Malay Peninsula, Sumatra, Java, Borneo, the larger 



