Cll FLORA OF TASMANIA. [Fossil Plants, 



means of answering. If the identifications of Banksia and other Proteaceous leaves in the Cretaceous 

 and Miocene formations of Europe are -worthy of any confidence, it is possible that the Australian 

 from the northern to the southern hemisphere, as, according to Darwin's types may have migrated 

 speculations, the existing European plants in Australia have. 



Some arguments in favour of the antiquity of the Australian Flora as compared with the Euro- 

 pean may be derived from a consideration of its generic and ordinal peculiarities. If, as I have 

 expressed it, a Genus or Order is rendered peculiar, that is, unlike its allies, by the extinction of the 

 intermediate species, it follows that the greater the peculiarity the greater the number of lapsed forms. 

 Applying this argument to the Australian Elora, we must assume an extraordinary destruction of 

 species that once linked it witli the general Flora of the globe, to account for its many peculiar genera, 

 and these being represented by so many species. But as this destruction of species is primarily due 

 to geological causes, that influence climates and so directly and indirectly lead to the extinction of 

 species, and as geological events are of slow progress, it follows that we must regard the Australian 

 Flora as a very ancient one. Again, Darwin argues that a rich Flora or Fauna, marked by a prepon- 

 derance of highly developed types, must have required a large area for its development : this is 

 because, according to his view, the principle of natural selection favours the high forms, and is 

 unfavourable to the low. Now it could be easily shown that the Australian Flora is of as high 

 a type as any in the globe, but under existing conditions has a very small area for its development, 

 and presents fewer representatives of other Floras to contend with than most ; and we must hence, 

 under these hypotheses, assume not only the antiquity of the Flora, but that it was developed in a 

 much larger area than it now occupies. 



The only other geological speculation, founded upon anything like plausible grounds, that bears 

 upon the origin of any of the plants now inhabiting Australia, is that of Mr. Darwin in reference to 

 the European species, to which I have alluded at p. xvii. It implies of course that the existing Euro- 

 pean types were introduced into the continent long subsequently to the peculiar Australian, and are 

 plants of a later creation. I have already pointed out the difficulties attending its adoption, the 

 chief of which is the admission of such a cold climate in the intertropical latitudes as that not merely 

 a temperate, but a decidedly northern Flora should have migrated across them ; and that this mi- 

 gration, if conceded, must have been extensive and have introduced very many genera and species into 

 the tropics appeal's likely, when we consider the fragmentary character of the assemblage of northern 

 forms still left in Australia, — for even when reduced to its most typical examples, it consists of nearly 

 as many Natural Orders as species. The little colony of south Australian genera found under the 

 Equator, on Kiui Balou, in Borneo, presents another difficulty, except indeed it be regarded as evi- 

 dence of that previous southern migration of Australian forms from Europe to Australia, which I 

 have just mentioned as conceivable. 



There are then the Antarctic types to account for ; were they of more recent introduction than 

 the European or Australian? Darwin has alluded to the possibility of these having been trans- 

 ported by icebergs from higher southern latitudes, during a period of greater cold than now obtains 

 in the southern hemisphere, (as the Scandinavian and Arctic plants are supposed by Forbes to have been 

 transported to Britain, etc., during the Glacial period), and, with the north European plants already in 

 Australia, to have ascended the mountains during the subsequent rise of temperature. This would 

 imply that Australia was, during a cold Tertiary period, simultaneously peopled by all those Antarctic, 

 European, and Australian types which now inhabit it, but that the latter Flora was much less developed 

 in number of species and genera than now ; for I cannot but regard the Antarctic Flora in the same 



