192 Ludwig Diets 



This list contains not only isolated monotypic genera (*), but 

 also polymorphous groups. We do not know where to look for 

 their affinities, and this corroborates the opinion that they were 

 separated from other tribes at an early date. Hence it appears that 

 Australia, where they were evolved, was isolated for a consider- 

 able length of time and not connected with southern regions dur- 

 ing this important period of its history. 

 Thus, for the southern element of the Australian flora, I find : 

 (i) That in eastern Australia, several true Antarctic genera 

 and species are found which may date from late immigrations. 



(2) That only a very few other southern threads appear in 

 the tissue of the Autochthonian flora. 



(3) That in the overwhelming majority of this Autochthonian 

 flora, no southern relations are indicated. 



These data are not compatible with the principal assumption 

 of Wegener's theory that Australia had drifted to the north quite 

 recendy, and had approached the continental block of south- 

 eastern Asia only yesterday. 



In order to test further the value of this assumption, it will be 

 useful to examine the Asiatic or Malesian elements in the flora of 

 Australia. 



Such Asiatic features present themselves in the more distant 

 relations of some Autochthonian genera, namely : 



Casuarina Eucalyptus 



Chenopodiaceae § Kochiinae Sterculiaceae § Buettnerieae 



Chenopodiaceae § Atriplicinae Myoporaceae genus Eremophila 



Acacia § Phyllodineae Rutaceae § Boronieae 



In Casuarina and Acacia § Phyllodineae, it is doubtful whether 

 the species indigenous in Malaysia originated in Australia, or, 

 on the contrary, whether the Australian species originally came 

 from the north. In other genera (Rutaceae § Boronieae, Eucalyp- 



