PRESIDENTIAL ADDRESS. 47 



Judging by its wide distribution, and considering that 

 this type of venation is practically identical with that of 

 the genus Angophora, and avoids the cold, the assumption 

 seems warranted that it belongs to the earliest form of 

 Eucalyptus leaf, and also was developed in a warm climate 

 in Northern Australia. 1 



Oblique venation. — A study of the oblique venation, or 

 that which is intermediate between the approximately 

 right angled and parallel venations, and of which E. globulus 

 may be regarded as a type, reveals the fact that the bulk 

 of the Eucalypts fall witbin this class. It is found that 

 they occur in the dry Interior and also well up on the 

 Mountain Region to elevations in a few cases of 5,000 feet. 

 This form is most strongly represented in the Coastal Area, 

 but that is largely because species and individuals are more 

 numerous in that division. It is also the dominant form on 

 the Western Slopes and in the Interior, in fact, except for 

 the two species with transverse venation mentioned as 

 occurring in those divisions, practically all other species 

 there belong to the oblique venation series. It is fairly 

 common in the Mountain Region between the altitudes of 

 2,000 and 4,000 feet, but becomes less plentiful above that 

 elevation, and practically ceases just above 5,000 feet. 



Considering the prevalence of this type of leaf all over 

 Australia, it seems a correct assumption that it is fairly 

 ancient, and was evolved from the transverse venation as 

 a form better suited to make progress amidst the surround- 

 ings in which it was placed. 



Parallel venation. — The type of leaf referred to as having 

 parallel venation, or having the lateral veins arranged at 

 an angle of less than about 25 degrees with the midrib, 

 belongs chiefly to the Mountain Region, and secondly to 



1 "The Tertiary Flora of Australia/' by H. Deane, m.a., Proc. Linn. 

 Soc. N.S. Wales, Vol. xxv, p. 474, (1900). 



