REGIONS AND AREAS OF DISTRIBUTION, 551 
only one is South-African, although in modern times several 
South-African Composite have shown a great aptitude to colonize 
in Australia. 
The distribution of Composite within the Australian region, 
the non-identity of eastern and western races, the number, diver- 
sity, and distinctness of genera and species in the south-western 
districts, giving them a marked character as a centre of preserva- 
tion of ancient races, the variability and confusion of specific 
forms in the Eastern States almost unexampled, except in New 
Zealand, showing a high state of specific luxuriance, now perhaps 
undergoing a process of differentiation, the evidences of an 
ancient engrafting of Antarctic races in the mountain-regions of 
Victoria and Tasmania, and of a less remote intrusion continued 
in recent times of Asiatic races in the northern and especially 
the north-eastern districts, are all questions of great interest, but 
requiring too much detail to be entered into on the present occa- 
sion. They cannot either be well treated in regard to Composite 
alone without regard to the general vegetation of the region. For: 
the general consideration of this subject we require a complete 
Flora of Australia drawn up on a uniform standard. Although I 
am now far advanced in this work, having now completed Dico- 
tyledons, it will yet take me two or three years to reach the end. 
Should life be so long spared to me, it is to be feared that age would 
then interfere with my working out satisfactorily the necessary 
comprehensive considerations, which, indeed, would be much better 
placed in the hands of those who have acquired a personal know- 
ledge of the country. 
7. Connexions between distant Old- World Regions. 
As in America, these are chiefly between north and south, but 
with rather more complication. The great Old- World continent, 
although nearly double the breadth of America, has no more than 
that continent any two distinct and distant east and west regions 
or endemic centres of Composite ; it has not even any north and 
south chain of mountains to interrupt by a climatological barrier 
the gradual east and west extension or modification of races. On 
the other hand, the independent position of Australia establishes 
a break, unconnected with climate, not observable in America. 
We have therefore to consider, besides the connexions between 
the Mediterranean or Europzo-Asiatic regions on the one hand, 
and the South-African on the other, the separate connexions of Aus- 
tralia with South Africa, with tropical Africa, and with tropical Asia. 
