THE SOUTH TEMPERATE ZONE 361 



southern hemisphere. Migrants from such a common temperate 

 flora, shut off in the at present widely sundered regions, would 

 in course of time show greater or less divergence, depending upon 

 the difference in environment. The cool humid climates of Fuegia, 



Tasmania and southern New Zealand would be more likely to 

 preserve these ancient forms with little change, than the hoi 

 arid climate of most of Australia and South Africa. 



There is sufficient similarity in the floras of South Africa and 

 Australia to warrant the assumption of some former land connec- 

 tions ; but such, if they did exist, were severed at a very remote 

 period. The high degree of endemism in the two regions, points 

 to a long period of isolation; and while, for example, such a pecu- 

 liarly southern family as the Proteaceae, is abundantly represented 

 in both regions, there is not a single genus common to the two. 



The rain-forests of Queensland and New South Wales are prob- 

 ably the remnants of a once much more extensive flora of Malayan 

 type. It is certain that at no very remote period, geologically 

 speaking, northeastern Australia and Papua were united, and this 

 is amply shown by both the floras and faunas of the two regions. 



Western Australia, however, is supposed to be part of a very 

 ancient continent which was at one time completely separated 

 from what is now eastern Australia. In this ancient western con- 

 tinent it has been thought that most of the peculiar autochtho- 

 nous Australian types originated. The typical Australian flora 

 shows a very high degree of endemism, this reaching its maximum 

 in Western Australia. The proportion of both endemic genera 

 and species is very high, but the number of families represented 

 is relatively small. The large number of species in certain genera 

 is notable. Thus the genus Eucalyptus has over 200 species, 

 and of the Leguminosae, the largest family in the Australian 

 flora, over 400 species, or approximately one third of the total 

 number, belong to the single genus Acacia. The Myrtaceae, the 

 second largest Australian family, has over 800 species and the 

 Proteaceae more than 650. 1 Several families, e. g., Candol- 

 leaceae, Goodeniaceae, are almost exclusively Australian, and 

 especially developed in West Australia. 



The typical Australian types are largely adapted to dry condi- 

 tions, and after the union of eastern and western Australia, it may 



1 Maiden, loc. cit., p. LI 



