CHAP. XVI.] 
SUMMARY AND CONCLUSION. 
157 
being due to a radical difference of type, and therefore not 
indicative of climate. The early European flora seems to have 
been a portion of that which now exists only in the tropical and 
sub-tropical lands of the Eastern Hemisphere ; and, as much of 
this flora still survives in Australia, Tasmania, Japan, and the 
Cape of Good Hope, it does not necessarily imply more than a 
warm and equable temperate climate. The early North Ameri- 
can flora, on the other hand, seems to have been essentially the 
same in type as that which now exists there, and which, in the 
Miocene period, was well represented in Europe ; and it is such 
as now flourishes best in the warmer parts of the United States. 
But whatever conclusion we may arrive at on the question of 
climate, there can be no doubt as to the distinctness of the floras 
of the ancient Nearctic and Palaearctic regions ; and the view 
derived from our study of their existing and extinct faunas — 
that these two regions have, in past times, been more clearly 
separated than they are now — receives strong support from the 
unexpected evidence now obtained as to the character and muta- 
tions of their vegetable forms, during so vast an epoch as is 
comprised in the whole duration of the Tertiary period. 
The general phenomena of the distribution of living animals, 
combined with the evidence of extinct forms, lead us to con- 
clude that the False arctic region of early Tertiary times was, 
for the most part, situated beyond the tropics, although it pro- 
bably had a greater southward extension than at the present 
time. It certainly included much of North Africa, and perhaps 
reached far into what is now the Sahara; while a southward 
extension of its central mass may have included the Abyssinian 
highlands, where some truly Pahearctic forms are still found. 
This is rendered probable by the fossils of Perim Island a. little 
further east, which show that the characteristic Miocene fauna 
of South Europe and North India prevailed so far within the 
tropics. There existed, however, at the extreme eastern and 
western limits of the region, two extensive equatorial land-areas, 
our Indo-Malayan and West African sub-regions — both of which 
must have been united for more or less considerable periods 
with the northern continent. They would then have received 
