474 THE TERTIARY FLORA OF AUSTRALIA, 



judge by its present distribution, must have originated in the Aus- 

 tralian region, as, with the exception of some endemic species in the 

 neighbouring islands, no species exist which are not Australian 

 and which are not likely to have been transported as seeds by 

 ocean currents. 



The capsular-fruited Myrtacece, although like the groups above- 

 mentioned specially fitted to flourish in South Africa, are never- 

 theless not found there. They probably, therefore, did not 

 exist in what is now Western Australia till after the land con- 

 nection with South Africa had broken up. Perhaps the most 

 likely theory would be that they originated in Northern or 

 North-eastern Australia, arriving at their greatest development 

 afterwards in Western Australia, while the fleshy-fruited section 

 of Myrtacece became differentiated at a later date (probably by 

 natural selection) and spread northwards and westwards into 

 Asia and Europe. In connection with the suggested origin of 

 the Myrtacea? in Northern Australia, it is to be remarked that 

 as one proceeds south to Victoria and Tasmania, although certain 

 species of Eucalypts attain an enormous development and 

 stature, the species become fewer in number, and other genera 

 which flourish further north disappear altogether. 



When we look at the enormous development that has taken 

 place in the zoological series since the beginning of the Tertiary, 

 and still more since the Jurassic Period, when the first Dicoty- 

 ledons made their appearance, it would seem strange if great 

 changes should not have taken place in the highest orders of the 

 Vegetable Kingdom. The great groups of Reptilia and Batrachia, 

 which had their highest development in the Mesozoic Age, have 

 taken up since the beginning of the Tertiary a subordinate 

 position; and the Aves and Mammalia, which were before the 

 latter period set in in the infancy of their development, 

 are now the dominant orders ; and what extraordinaiy 

 evolution between the beginning of the Tertiary and the 

 present time ! Is it not probable that some considerable 

 development has also taken place in the highest orders of 

 plants 1 It ma}'- be quite possible that the great groups, and 



