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

chap, xi.] THE ETHIOPIAN REGION. 261region, and it suggests some curious speculations as to the formerhistory of that region, a subject which must be deferred to thelatter part of this chapter. In none of the other great tropicalregions does it occur, that the largest portion of their area,although swarming with life, yet possesses hardly any distinctivefeatures except the absence of numerous types characteristic ofthe other sub-regions.Plate IV.— Illustrating the Zoology of East Africa.—Althoughthis sub-region has so little speciality, it is that which aboundsmost in large animals, and is, perhaps, the best representative ofAfrica as regards zoology. Some of the most distinctive of Africananimals range over the whole of it, and as, from recent explorations,many parts of this wide area have been made known to thereading public, we devote one of our plates to illustrate theespecially African forms of life that here abound. The antelopesrepresented are the koodoo (Tragclaphus strepsiceros) one of thehandsomest of the family, which ranges over all the highlandsof Africa from Abyssinia to the southern districts. To the leftis the aardvark, or earth pig, of North Eastern Africa {Orycteropuscethiopicus) which, to the north of the equator in East Africa,represents the allied species of the Cape of Good Hope, TheseEdentata are probably remnants of the ancient fauna of Africa,when it was completely isolated from the northern continentsand few of the higher types had been introduced. The largebird in the foreground is the secretary-bird, or serpent-killer(Serpentarius rcptilivorus), which has affinities both for the birdsof-preyand the waders. It is common over almost all the opencountry of Africa, destroying and feeding on the most venomousserpents. The bird on the wing is the red-billed promerops(Irrisor erythrorhynchus), a handsome bird with glossy plumageand coral-red bill. It is allied to the hoopoes, and feeds oninsects which it hunts for among the branches of trees. Thisspecies also ranges over a large part of east and central Africa tonear the Cape of Good Hope. Other species are found in thewest ; and the genus, which forms a distinct family, Irrisoridm, isone of the best marked Ethiopian types of birds. In the distanceisa rhinoceros, now one of the characteristic features of African