CHAP, XI.] THE ETHIOPIAN REGION. 291 
tolerable rapidity, or if the elevatory force acted from the north 
towards the south, there would be a new and unoccupied 
territory to be taken possession of by immigrants from the 
north, together with a few from the south and west. The more 
highly-organized types from the great northern continent, how- 
ever, would inevitably prevail; and we should thus have 
explained the curious uniformity in the fauna of so large an 
area, together with the absence from it of those peculiar 
Ethiopian types which so abundantly characterise the other 
three sub-regions. 
We may now perhaps see the reason of the singular absence from 
tropical Africa of deer and bears; for these are both groups 
which live in fertile or well-wooded countries, whereas the line 
of immigration from Europe to Africa was probably always, as 
now, to a great extent a dry and desert tract, suited to antelopes 
and large felines, but almost impassable to deer and bears. We 
find, too, that whereas remains of antelopes and giraffes abound 
in the Miocene deposits of Greece, there were no deer (which 
are perhaps a somewhat later development); neither were there 
any bears, but numerous forms of Felidz, Viverridz, Mustelide, 
and ancestral forms of Hyawna, exactly suited to be the 
progenitors of the most prevalent types of modern African 
Zoology. } 
There appears to have been one other change in the geo- 
graphy of Africa and the Atlantic Ocean that requires notice. 
The rather numerous cases of close similarity in the insect 
forms of tropical Africa and America, seem to indicate some 
better means of transmission, at a not very remote epoch, than 
now exists. The vast depth of the Atlantic, and the absence of 
any corresponding likeness in the vertebrate fauna, entirely 
negative the idea of any union between the two countries ; 
but a moderate extension of their shores towards each other is 
not improbable, and this, with large islands in the place of the 
Cape Verd group, St. Paul’s Rocks, and Fernando Noronha, to 
afford resting places in the Atlantic, would probably suffice to 
explain the amount of similarity that actually exists. 
Our knowledge of the geology and paleontology of Africa 
