BY E. C. ANDREWS. 559 



development of the wax-bloom on the tender parts of the plant, 

 appear also to be provisions against aridity.* 



A group of the new genus appears to have detached itself gradu- 

 ally from the Corymbosse members, and to have pressed its way far 

 to the south. This was made possible by the protection of the ten- 

 der reproductive organs, partly by the operculum during the 

 earlier stages, and partly by reason of the thick capsule generally, 

 for the typical Myrteae have never been enabled to move far from 

 the tropics, owing to the tender nature of their structures. This 

 southward-moving group acclimatised itself to temperate, moist, 

 and sheltered conditions, and there, it tended to revive the old, 

 opposite, cordate, sessile, and horizontal leaves of the tribe, where- 

 as the early, or corymbose, Eucalypts had practically discarded 

 such leaf -types. The thinness and delicacy of the juvenile leaves 

 belonging to some of these southern forms, suggest a development 

 in the absence of strong light. The abundant development of 

 eineol, among these types, also suggests protection from severe 

 climatic conditions. Survivals of these types include E. globulus, 

 E. goniocalyx, and E. Maideni. More modified types are E. Cam- 

 bagei and E. rubida. In this group, the generalised type of anther 

 for the Order is unaltered. 



Another section with opposite juvenile leaves, is represented by 

 types such as E. viminalis, E. amygdalina, and E. radiata. These 

 opposite, sessile leaves, however, in order to adapt themselves to 

 varied conditions, have adopted a thicker leaf-type, the breadth of 

 the leaf is much reduced, and the leaf is held almost vertically. 



At a much later period, namely, after the formation of the great 

 plateaus of Eastern Australia, these Eucalypts gradually worked 

 their way northwards as far as Queensland, and, to-day, along the 

 plateaus, one may see the effect of this wonderful reinvasion by 

 southern Eucalypt-types. 



But prior to this stage, the eastern side of Australia became 

 flooded with basalts ; and heavy, rich clay-soils were formed in the 

 area which had been vacated by the Cretaceous Sea. The Boxes 



* Robert Brown, quoted by Schimper, in Plant-Geography. 



