ON THE INFLUENCE OF PHYSIOGRAPHIC CHANGES. 323 



the endemic species of the Euronotian and Eremian floras belong 

 to a relatively large number of ex era- Australasian genera, but 

 the Euronotian flora contains a few representatives of that 

 primitive flora which marks the close of the Cretaceous and the 

 early stages of the Tertiary Period, the existence of which in 

 Pre-Pliocene times in Australia, has been made known chiefly by 

 the researches of Baron von Ettingshausen. The forms belonging 

 to this type of vegetation, which still linger with us, are Cinnam- 

 omu/n, Ulmus, Fagus, Araucaria, Cassia, Sapindus, Panax, 

 Zitscea, Zizyphus, Callitris, and in an extension to New Guinea, 

 Quercus. 



In association with the fossil representatives of these genera, 

 are progenitors of such genera as Dryandra, Lomaria, Casuarina, 

 Eucalyptus, Dammara and others, which indicate that the early 

 flora of this Continent had then impressed on it those botanical 

 features which make it so conspicuous in living vegetation. These 

 Australian types are mingled with the Old World forms in the 

 Eocene-Cretaceous floras of North America and Europe, as they 

 are in Australia, and renders it diflicult to assign an earlier date 

 to the one in preference to the other. 



Keeping in mind the fact of the absence of primitive types of 

 the Old AVorld flora* in the Autochthonian Region, its highly 

 specialised Australian types, and its long continued isolation from 

 the rest of Australia, which I have endeavoured to establish on 

 physical evidences, may not the Autochthonian floi'a be regarded 

 as of greater antiquity ; and that the modification of the Aus- 

 tralian flora in the Euronotian Region by an equally primitive 

 flora of European ty|3e, was subsequently acquired chiefly by 

 reason of less remoteness of this part of Australia, and for the 

 same reason has it continued into recent times to receive greater 

 accessions of Asiatic races. 



It is to be deplored that we have no knowledge of the Tertiary 

 flora of the Autochthonian Region, but I hope that some efi'ort 

 will be made to eliminate this desideratum, and would call 

 particular attention to the gorge of the Fitzgerald River as 

 aflbrding a field of investigation, the lignitiferous bed at which 

 place is, in the opinion of Mr. S. Dixon, f contemporaneus with 

 the Old Tertiary. 



The history of the Australian floras, viewed chronologically, 

 may be summarized as follows : — 



The Australian flora is of high antiquity. 



The Autochthonian constituent was dismembered in Cretaceous 

 times. 



The Euronotian constituent was modified during very early 

 Tertiary times by a primitive cosmopolitan flora. 



That it was further moditied during the Glacial Epoch of the 

 Southern Hemisphere by an incursion of Andean types. 



* Dryandra has one Eocene species, and Adenanthon has one species Senonien. 

 t Trans. Roy. Soc . South Australia, 1884, Vol. VII ., p. 9. 



