*96 RECORDS OF THE AUSTRALIAN MUSEUM. 



forms there is no doubt, for four or five species occur in both 

 Papuasia and Australia, while Hyla infrafrenata (H. dolichopsis, 

 Cope, auctornm) is known from Java, Ceram, New Guinea, New 

 Ireland and North Australia. This is, however, easily explained 

 if we take into consideration the existence of a connection in 

 recent Tertiary times, between Cape York and New Guinea, 

 which in all probability also allowed the transmission of 

 Plianerotis nov(e-guinece into Papua and Ratia papua into 

 Australia. Referring again to Gadow's 7 admirable chapters on 

 distribution, he says of the Hylidse, " with this exception of three 

 closely allied species, the Hylidse are either American or Austral- 

 ian. We conclude that their original home was Notogaea, and 

 that they have spread northwards through Central and into 

 North America. The enormous moist and steamy forests of South 

 America naturally suggest themselves as a paradise for tree- 

 frogs, and it is in this country, especially in the Andesian and 

 the adjoining Central American Sub-regions, that the greatest 

 diversity of generic and specific forms has been produced. It is 

 all the more remarkable that similar forest regions, like those of 

 Borneo and other Malay islands, are absolutely devoid of Hylidte 

 ( while there are about a dozen species in Papuasia), whose place has 

 been taken for all practical purposes by correspondingly developed 

 Pallida?, notably the genus Rhacophorus. Lastly, the fact that 

 tropical evergreen forests of Africa and Madagascar possess no 

 Hylidse, but are inhabited by several kinds of tree-climbing 

 Rhacophoms, points with certainty to the conclusion that the 

 origin of this large and flourishing family of Hyliche was not in 

 Arctogaea." 



The absence of Hyliche in the Malay Archipelago, or more 

 strictly speaking Siam, Borneo and Sumatra, is very striking and 

 is in itself fatal to the theory that Papuasia could have been the 

 centre of dispersion of Arctogaean Hyliche. Allowing this to be 

 possible, two questions remain to be explained. First, during 

 the extension westwards of the three Asiatic Hvlas why did they 

 not also populate Siam, Borneo and Sumatra, through which 

 countries they must have passed ; and, allowing a rapid extension 

 southwards to Australia and Tasmania, why did they not extend 

 southwards at their western limit into the highly favourable 

 forests of Africa] Secondly, it is obvious that to allow this mode 

 of precedure we must regard the Arctogaean Hyliche as cases of 

 convergent evolution. As would be expected there is consider- 

 able parallelism in development amongst New World and 



T Gadow— Cainbr. Nat. Hist., Rept. & Amph., 1901, p. 186. 



