16 The Philippine Journal of Science 1923 



the Macassar Strait, like its southward extension between Bali 

 and Lombok, has not been of so long-continued and permanent 

 a nature as the Macassar Strait (see Plate 2). 



Weber's Line extends between Timor and Australia, running 

 northwestward between the Kei and Aru Islands, then turns 

 to the northeast and east through the Ceram Sea north of 

 Ceram and Buru, and finally northward through the Molucca 

 Passage and into the Pacific Ocean between Celebes and 

 Halmaheira. Molengraaff 1T states that the trough sea or series 

 of trough seas consisting of the Timor Sea separating Timor 

 from Australia, the Kei trough, the Ceram trough, and the 

 Ceram Sea is a most important geologic boundary, as it sepa- 

 rates totally different structures from each other. He states 

 that the nonvolcanic islands of this arc originated as oceanic 

 ones by anticlinal folding and that, geologically, they stand in 

 close relationship with eastern Asia but have no connection at all 

 with Australia. If we are to accept a geologic boundary between 

 Australia and Asia, then the boundary must be drawn between 

 Timor and Australia and between Ceram and New Guinea. 

 This sharp geologic boundary is also an important dividing 

 line from a zoogeographic standpoint, as Weber has pointed out, 

 for the fresh-water fishes. Molengraaff notes that the boundary 

 is not so sharp a dividing line in other groups of animals as 

 is the case with the fresh-water fishes but, in spite of this, it 

 is important for all groups. It would seem that the significance 

 of Weber's Line, like that of Wallace's Line, as a biological 

 boundary, is due primarily to fundamental geologic conditions. 

 Wallace's Line cannot be abandoned in favor of Weber's Line 

 or vice versa; the former is merely the eastern boundary of the 

 unstable insular area, and the latter is apparently the approxi- 

 mate western boundary of the same terrane and bears much 

 the same relationship to New Guinea and Australia as Wallace's 

 Line bears to Asia or, rather, the former eastern boundary of 

 the Asiatic continent. 



Weber," followed by Van Kampen » has clearly shown that 

 the entire region from Celebes and Lombok to New Guinea is a 



"Geologie in: De zeeen van Nederlandsch Oost-Indie (1921) 272-357, 



"Weber, M., Der Indo-australische Archipel und die Geschichte seiner 

 Tierwelt (1902). 



"Van Kampen, P. N., De Zoogeografie van den Indischen Archipel, Nat 

 Tijdschr. Nederl. Ind. (1909) Bijblad 3, 4; English translation, Am. Nat! 



