58 R. H. CAMBAGE. 



the parallel venation, and the bulk of those whose leaves 

 yield the greatest quantities of phellandrene oil. 



It is freely conceded that the typical characters referred 

 to are not absolutely the product of any one condition, nor 

 would such a result be expected when the great range and 

 the variation of this large genus are considered, and while 

 the varying geological formations with their diverse 

 amounts of silica and alkalies have been amongst the most 

 important factors in regulating the development of the 

 Eucalypts, the dominating influence which is broadly 

 responsible for the regulation of their distribution over the 

 whole continent is that of climate. 



