BY THE REV. DR. WOOLLS. 323 



distribution of the Tertiary Flora, from which the recent one has 

 been developed, also with the changes in the physical geography of 

 the continent which have directed that distribution. Imagine the 

 luxuriant condition of the vegetation, especially upon South-eastern 

 Australia, during the great rainfall period which immediately 

 preceded the recent flora, when the great Eiverina Plains were 

 formed by higher floods than those occurring at the present day ; 

 and when crocodiles sported in swampy jungles along the Darling 

 River in places 15 miles distant from the river, and now dry plains! 

 In that period Lake Torrens and Lake Eyre were probably 

 connected with Spencer's Gulf and stretched northward far into 

 the continent. Then, in the previous Miocene times, Australia 

 stood at a lower level, and the ocean occupied all that low country 

 between Speiicer^s Gulf and Western Australia. Then again in the 

 Cretacean period, about two-thirds of Australia onust have been 

 under the ocean. Under these conditions how did the plants migrate'? 

 And with alteration of the form of sea and land, the ocean currents, 

 with warm or cold water, as the case might have been, varied 

 accordingly and affected the temperature of the climate of the 

 different localities ; for along the coast 7iear Adelaide the rocks 

 are grooved with glacier strise. These changes of temperature, 

 therefore, and of rainfall, must at times have greatly favoured the 

 growth of certain plants, and the diminution or extinction of 

 others until the present distribution resulted." It would be 

 presumptuous in me to pursue this subject any further, but I can 

 easily imagine that, at a period when Eastern and Western Aus- 

 tralia were separated by an intervening sea, the migration of many 

 plants from the west (a migration which had probably commenced) 

 was rendered impossible ; and this may account for the fact that 

 so many forms of vegetation have remained isolated from the rest 

 of Australia, and that the flora of the S.W. is richer than that of 

 the S.E. Anyone by studying the census of plants, as furnished 

 by Baron Mueller, must see how, in some genera truly Australian, 

 the species are all limited to the west, and how, in other genera, 

 a few species only have found their way east. How can such 

 things have happened unless some great physical changes have 



