HORN KXPEniTION — SUMMARY. 17") 



In comipction witli tliis it may lie iiotod that tliorc is consideralilo diircronco 

 of opinion with rog;irfl to the existence of a cosmopolitan floi-a in the sense in 

 wliicli the term is used hy Professor Tate wlien speaking of " tliat primitive flora 

 which marks tlie close of the Cretaceous and the early stages of the Tertiary 

 period, as has been made known chiefly hy the i-esearches of Jlaron von 

 Ettingshausen." If such a flora did exist then it is somewhat diflicult (o 

 understand the relationships of the flora of the Autochthonian region. 



The date of the prevalence of this supposed cosmopolitan flora is given by 

 Professor Tate in his general conclusions refeiring to the Lai'apintine flora 

 (Botanical Report, p. ISH), as Supra-Cretaceous and continuing into Paleocene 

 times. That is, it originated subsequently to the time at which the Cretaceous sea., 

 in which the great Rolling Downs formation was deposited, separated the western 

 island off from the eastern coastal area, and during which time the Autochthonian 

 flora which subsequently spread eastwards wa.s being developed. This Autoch- 

 thonian flora, which on this supposition antedated the cosmopolitan flora, alieady 

 contained the now more typical series of Australian forms, the Euronotian 

 having been more modiiied by Oriental and Andean inunigration. If the present 

 typical Australian flora i.s to be regarded as deiived fiom the Autochthonian, then 

 it is somewhat diflicult to see the exact role played l)y a cosmopolitan flora which 

 appeared on the scene after the development of the present typical Austi'alian flora. 



If it be, on the other hand, suggested that this Autochthonian itself is to be 

 regarded as a part of the cosmopolitan flora,* then it is a somewhat curious fact 

 that in the present western flora, which has been to a very large extent (in the 

 restricted area to which Professor Tate has applied the name of Autochthonian 

 region) shut oft' by barriers from an immigration of Oriental and Andean types, 

 we only find, and abundantly so, representatives of typical Australian geneia. and 

 not a trace of such doubtful forms as (.^uercus, Betula, Salix, etc., upon the 

 presence of which in fossil remains the theory of the cosmopolitan floia in Australia 

 really rests. If the Autochthonian was directly derived from the cosmopolitan flora, 

 then we might surely have expected to find some relics of such genera, and the 

 entire absence of them and the presence amongst endemic g(inera of only the 

 typical Australian flora of the pi'esent day seems to be, so far as it goes, strong 

 evidence against the existence of Raroii von Ettingshausen's cosmopolitan flora. 



* 111 this case of course the date of the cosiiio)iolitan flora iiiiist lie assigned to an earlier period than Supra- 

 Cretaceous and I'aleoceiie or e\eii late L'retaceous as the Autochthonian flora, as Professor Tate saj'.s, was 

 " disnieiiibcred in Cntaceous times," in fact, during Upper Cretaceous times it was isolated by the sea in which 

 the Rolling Downs formation was deposited. 



