23,1 Men-ill: Distribution of Dipterocarpaceae 19 



list of species definitely shows that they were, like those of 

 to-day, typical low-altitude tropical forests. I fail to see how 

 the claim can be substantiated that, as a result of the cooling 

 off in Pleistocene times, the vegetation was dislocated an entire 

 height zone (approximately 800 meters). Incidentally, this 

 would involve at most a change in the mean average annual 

 temperature of but about 5° C, if we may judge Pleistocene 

 weather conditions by modern ones in the Philippines and Java 

 (see Table 2). It seems more probable, if there was any ap- 

 preciable change in temperature at low altitudes in Java during 

 Pleistocene times, that it was even less than is here indicated 

 as the modern difference between the first and the second height 

 zones. In temperate regions the difference in average tem- 

 perature required to cause Pleistocene glaciation is estimated 

 at but 6° C, but this difference in tropical regions would be 

 relatively insignificant. 



Table 2.— Mean annual temperatures for various stations in the Nether- 

 lands East Indies, and the Philippines at sea level and at the approxi- 

 mate lower level of the second vegetation zone. 



Altitude Mean annual 

 m. °C. 



Dansalan - ™1 22 8 



Doctor Schuster, like others, disproves the existence of 

 Wallace's Line, basing his refutation upon his interpretation 

 of the paleobotanical evidence. He claims that Wallace's Line 

 existed in Pleistocene times just as little as it does to-day. Schus- 

 ter to the contrary notwithstanding, the botanical evidence, like 

 the zoological, geological, and hydrographic evidence, indicates 

 a definite distinction between eastern and western Malaysia. 

 The principal part of the line of demarcation is the Macassar 

 Strait, geologically the oldest part of Wallace's Line. 



Doctor Schuster postulates successive waves of migration of 

 Asiatic types to the east in Pliocene times, of which he differen- 



