1S2 E. C. Andrews — The Geological History of the 



fossils of the Cretaceous and Tertiary beds to modern genera 

 straight out even when those particular genera no longer exist 

 either in or near the regions considered. The particular cases 

 which come to the mind of the Australian geologists in this 

 connection are the well-known references of Cretaceous and 

 Eocene leaf remains in North America and Europe to the 

 modern genera Eucalyptus, Hakea, Grevillea, Banksia, Dry- 

 andra, Callistemon, and other types now found only in 

 Australia, and of various Tertiary leaf remains in Australia 

 to Quercus, Alnus, Acer, and other genera, not now existent 

 in Australia. 



These determinations, moreover, appear to he opposed to the 

 general evidence available on the subject because : — 



First. — The vitality, vigor and aggressiveness of the genera, 

 such as Eucalyptus, Grevillea, Hakea, Persoonia, BanJcsia, 

 and Dryandra, is very decided. Anyone who has made a close 

 study of Eucalyptus must have observed its adaptation to all 

 varieties of moisture, climate and soil in Australia, exclusive 

 of jungle areas. All round Australia it extends, flourishing on 

 the actual sands immediately behind the sea beaches, swarming 

 up the sides of the mountain gorges, defying the desolating 

 winds of the cold plateaus and the desiccating influence of the 

 arid to subarid climate of the plains and straining at its fet- 

 ters, as it were, as though eager to conquer other areas than 

 Australia. In other words it acts as though it were a genus 

 which has not yet reached its prime. 



On the sandy areas, especially in West Australia, the same 

 remarks are true, although in a measure somewhat slighter, 

 of the vast genera Grevillea and Hakea, and the large genera, 

 Persoonia, Banksia, and Dryandra. Nevertheless, vigorous 

 and aggressive as are all these types to-day in Australia, it is 

 stated that in extra-Australian regions they became so unfitted, 

 one and all, to survive that they were driven out of the last 

 trench even in Africa, a country whose soil and climate is 

 similar in many ways to that of Australia. 



This difficulty is accentuated especially when the apparent 

 saltation of Eucalyptus, in the eastern portion of Aiistralia, is 

 considered, many disputes having arisen as to specific deter- 

 minations by highly-trained Australian botanists of certain 

 forms found in that region. 



Second. — These types, Eucalyptus (300 species), the pliyl- 

 lodineous acacias (420 species), Grevillea (200 species), Hakea 

 (110 species), Persoonia (62 species), BanJcsia and Dryandra, 

 each about 50 species, are all xerophytic. Their ancestors 



