3 ANNALS NEW YORK ACADEMY OF SCIENCES 



reentrants into the area of origin, and that the great result of speciation 

 which we see now in the southern headquarters of Hylids and Cystig- 

 nathids shows that this region was peripheral in relation to their area of 

 origin. The steps of reasoning whereby Matthew arrives at these con- 

 clusions are carefully presented in his essay and there is no object in 

 recounting them here. 



It is of the general question of land bridges and of the relation which 

 some islands bear to continents that I have been thinking for some time, 

 and it is only because I have had some field experience and have given 

 thought to these matters that I have the temerity to take issue with Dr. 

 Matthew, knowing full well that many will maintain that his opinion 

 outweighs mine — a possible assertion I am by no means ready to deny. 



I take exception to statements such as this, where in speaking of land 

 bridges (p. 179) Matthew says, "I can see no good reason why the only 

 animals which availed themselves of such continental bridges should be 

 the ones which might be accounted for in other ways, while those which 

 would furnish conclusive proof are invariably absent." (Italics are 

 mine.) I have maintained elsewhere that a waif fauna is easily recog- 

 nized as such, and that the presence of burrowing amphibia, onycho- 

 phores, cyprinodont fishes and many other groups of delicate organisms 

 which are balanced to one particular environment cannot by any stretch 

 of the imagination be distributed by "flotsam and jetsam" methods; and 

 further that the element of the vast extent of geologic time does not in 

 any way affect the probability of such dispersal, since it cannot be sup- 

 posed ever to occur. 



Again, on page 187, we read that Austromalaya is the debatable ground 

 between the Oriental and the very distinct Australian region; but that 

 the consensus of opinion classes it by preference with the Australian. It 

 includes, we are told, Celebes, the Moluccas, Timor and the smaller 

 islands and is separated from the Oriental region by ^Wallace's Line." 

 This is surely a step backward, for "Wallace's Line" marks the limit of 

 but a small fraction of the whole species total of the Indonesian fauna, 

 while the area from the Lesser Sunda Islands and Celebes on the one 

 hand to Papuasia on the other represents a great transition zone, where a 

 dominance of Malayan types may be found in the western part which 

 merges into a predominance of Australian tyj)es in Papua. There is no 

 real boundar}'^ line in the entire area and no reason to expect one. 



Again Dr. Matthew in his "Summary of Evidence" (p. 308) states 

 that "the continental and oceanic areas are now maintained at their dif- 

 ferent levels chiefly through isostatic balance and it is difficult to believe 

 that they could formerly have been reversed in any extensive degree." 



