The geographical distribution of animals, with a study of the relations ...

chap, xi.] THE ETHIOPIAN REGION. 291tolerable rapidity, or ifthe elevatory force acted from the northtowards the south, there would be a new and unoccupiedterritory to be taken possession of by immigrants from thenorth, together with a few from the south and west. The morehighly -organized types from the great northern continent, however,would inevitably prevail ; and we should thus haveexplained the curious uniformity in the fauna of so large anarea, together with the absence from it of those peculiarEthiopian types which so abundantly characterise the otherthree sub-regions.We may now perhaps see the reason of the singular absence fromtropical Africa of deer and bears ; for these are both groupswhich live in fertile orwell-wooded countries, whereas the lineof immigration from Europe to Africa was probably always, asnow, to a great extent a dry and desert tract, suited to antelopesand large felines, but almost impassable to deer and bears.find, too, that whereas remains of antelopes and giraffesWeaboundin the Miocene deposits of Greece, there were no deer (whichare perhaps a somewhat later development) ; neither were thereany bears, but numerous forms of Eelidse, Viverridge, Mustelidse,and ancestral forms of Hycona, exactly suited to be theprogenitors of the most prevalent types of modern AfricanZoology.There appears to have been one other change in the geographyof Africa and the Atlantic Ocean that requires notice.The rather numerous cases of close similarity in the insectforms of tropical Africa and America, seem to indicate somebetter means of transmission, at a not very remote epoch, thannow exists. The vast depth of the Atlantic, and the absence ofany corresponding likeness in the vertebrate fauna, entirelynegative the idea of any union between the two countries ;but a moderate extension of theirshores towards each other isnot improbable, and this, with large islands in the place of theCape Verd group, St. Paul's Eocks, and Fernando Noronha, toafford resting places in the Atlantic, wrould probably suffice toexplain the amount of similarity that actually exists.Our knowledge of the geology and palaeontology of Africa