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THE DEVELOPMENT OF THE NATURAL ORDER 

 MYRTACE.E. 



By E. C. Andrews, B.A., F.G.S. 



Table of Contents. 



Introduction. The peculiar assemblages of Australian plants. 



Acknowledgments. 



Thesis. 



Geography. Climate, land-forms, and soils during Cretaceous, Tertiary, 

 and Post-Tertiary time in Australasia. 



Distribution of Myrtace^. Common throughout the tropics. Greatest 

 number of species in Tropical America, Australia next in importance, 

 but containing less than half the number of species in Tropical America. 



Earlier Forms of Myrtace^e. Allied to Myrteae. 



Home of the Earlier Forms. In the extensive tropical areas of the 

 Cretaceous world. 



Differentiation of Myrtacbjb. Myrtese the earlier types; Eu-Lepto- 

 spermese and Metrosiderea? deployed from Myrtea? in regions near 

 Northern Australia — Eucalyptese descended from ancestors of Metro- 

 siderea;, and Eucalyptus became acclimatised to both arid and cold 

 moist conditions— Chamaelaucieae and Beaufortieae more recent de- 

 scendants from Leptospermea? and Melaleuca respectively. 



Introduction. — The present distribution of two Natural Orders 

 of plants was considered with reference to their probable geographi- 

 cal environment in the past, and the environment, thus suggested, 

 was compared with that succession of Cretaceous and Tertiary geo- 

 graphies, which had been deduced years before by the writer from 

 physical data alone. The Orders Myrtaceae and Leguminosse were 

 the two chosen in this connection, but the former alone is con- 

 sidered in the present paper. 



Such a comparison was suggested by a knowledge of the peculiar 

 assemblage of plants growing on the coarse, acid sandstone of the 

 Sydney and Blue Mountain Districts. Although the sandy soil of 

 this district appeared to be exceedingly sterile, nevertheless it sup- 



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