254 ^' ^' ^^^^^^^ 



Calamian group in the Philippines. In its fauna and flora this 

 entire region is essentially Asiatic or, we might say, Malay- 

 Asiatic. Marked by the 200-meter isobath, the eastern boundary 

 of this shelf is, in its southern part, the famous Wallace's Line, so 

 named by Huxley, supposedly demarking the limits of the 

 Asiatic and the Australian faunas and a part of the eastern 

 boundary of the ancient Malay-Asiatic continent, or Sundaland. 



The Australian bank, or Sahul shelf, much smaller than the 

 Asiatic one but having practically the same history, carries upon 

 it the great island of New Guinea. The western boundary of this 

 ancient continent, or Papualand, approximates the position of 

 Weber's Line, proposed by Pelseneer as a substitute for Wallace's. 



The insular area between Wallace's and Weber's Lines, includ- 

 ing the Lesser Sunda Islands, the Moluccas, Gilolo, Celebes, and 

 all the Philippines except the Palawan-Calamian group, has had 

 an entirely different history. All or part of this intermediate 

 region has been insular since the beginning of the Tertiary. 

 There are no large shelf seas; on the contrary, the straits and 

 seas between the various islands are marked by great deeps. This 

 entire region has been subject to several great elevations and 

 depressions. It has been and still is unstable, and, in contrast to 

 the more stable Sundaland to the west and Papualand to the 

 southeast, it is orogenetically active. Its flora and fauna are made 

 up in part of relic species and their descendants, and in part of 

 infiltrations from the west, north, and southeast. East of Sumatra, 

 Java, and Borneo, Asiatic types sharply decrease; many do not 

 extend to this intermediate area, and still more do not reach New 

 Guinea. West of New Guinea, the Australian types decrease and 

 most of them do not reach Sundaland, although a striking series 

 has attained a northward distribution into the more distant 

 Philippines. 



