In the enormous tribe of Longicorns, or long-horned beetles, the Ethiopian is not so rich as the other three tropical regions; but this may be, in great part, owing to its more productive districts having never been explored by any competent entomologists. It nevertheless possesses 262 genera, 216 of which are peculiar, the others being mostly groups of very wide range. Out of such a large number it is difficult to select a few as most characteristic, but some of the peculiarities of distribution as regards other regions may be named. Among Prionidæ, Tithoes is a characteristic Ethiopian genus. A few species of the American genera Parandra and Mallodon occur here, while the North Temperate genus Prionus is only found in Madagascar. Among Cerambycidæ, Promeces is the most characteristic. The American genera Oeme and Cyrtomerus occur; while Homalachnus and Philagathes are Malayan, and Leptocera occurs only in Madagascar, Ceylon, Austro-Malaya, and Australia. The Lamiidæ are very fine; Sternotomis, Tragocephala, Ceroplesis, Phryncta, Volumnia, and Nitocris, being very abundant and characteristic. Most of the non-peculiar genera of this family are Oriental, but Spalacopsis and Acanthoderes are American, while Tetraglenes and Schœnionta have been found only in East and South Africa and in Malaya.
Terrestrial Mollusca.—In the extensive family of the Helicidæ or snails, 13 genera are represented, only one of which, Columna, is peculiar. This region is however the metropolis of Achatina, some of the species being the largest land-shells known. Buliminus, Stenogyra, and Pupa are characteristic genera. Bulimus is absent, though one species inhabits St. Helena. The operculated shells are not very well represented, the great family of Cyclostomidæ having here only nine genera, with but one peculiar, Lithidion, found in Madagascar, Socotra, and Arabia. None of the genera appear to be well represented throughout the region, and they are almost or quite absent from West Africa.
According to Woodward's Manual (1868) West Africa has about 200 species of land-shells, South Africa about 100, Madagascar nearly 100, Mauritius about 50. All the islands have their peculiar species; and are, in proportion to their extent, much richer than the continent; as is usually the case.
The Ethiopian Sub-regions.
It has been already explained that these are to some extent provisional; yet it is believed that they represent generally the primary natural divisions of the region, however they may be subdivided when our knowledge of their productions becomes more accurate.
I. The East African Sub-region, or Central and East Africa.
This division includes all the open country of tropical Africa south of the Sahara, as well as an undefined southern margin of that great desert. With the exception of a narrow strip along the east coast and the valleys of the Niger and Nile, it is a vast elevated plateau from 1,000 to 4,000 feet high, hilly rather than mountainous, except the lofty table land of Abyssinia, with mountains rising to 16,000 feet and extending south to the equator, where it terminates in the peaks of Kenia and Kilimandjaro, 18,000 and 20,000 feet high. The northern portion of this sub-region is a belt about 300 miles wide between the Sahara on the north and the great equatorial forest on the south, extending from Cape Verd, the extreme western point of Africa, across the northern bend of the Niger and Lake Tchad to the mountains of Abyssinia. The greater part of this tract has a moderate elevation. The eastern portion reaches from about the second cataract of the Nile, or perhaps from about the parallel of 20° N. Latitude, down to about 20° S. Latitude, and from the east coast to where the great forest region commences, or to Lake Tanganyika and about the meridian of 28° to 30° E. Longitude. The greater part of this tract is a lofty plateau.
The surface of all this sub-region is generally open, covered with a vegetation of high grasses or thorny shrubs, with scattered trees and isolated patches of forest in favourable situations. The only parts where extensive continuous forests occur, are on the eastern and western slopes of the great Abyssinian plateau, and on the Mozambique coast from Zanzibar to Sofala. The whole of this great district has one general zoological character. Many species range from Senegal to Abyssinia, others from Abyssinia to the Zambesi, and a few, as Mungos fasciatus and Phacochœrus æthiopicus, range over the entire sub-region. Fennecus, Ictonyx, and several genera of antelopes, characterise every part of it, as do many genera of birds. Coracias nævia, Corythornis cyanostigma, Tockus nasutus, T. erythrorhynchus, Parus leucopterus, Buphaga africana, Vidua paradisea, are examples of species, which are found in the Gambia, Abyssinia and South East Africa, but not in the West African sub-region; and considering how very little is known of the natural history of the country immediately south of the Sahara, it may well be supposed that these are only a small portion of the species really common to the whole area in question, and which prove its fundamental unity.
Although this sub-region is so extensive and so generally uniform in physical features, it is by far the least peculiar part of Africa. It possesses, of course, all those wide-spread Ethiopian types which inhabit every part of the region, but it has hardly any special features of its own. The few genera which are peculiar to it have generally a limited range, and for the most part belong, either to the isolated mountain-plateau of Abyssinia which is almost as much Palæarctic as Ethiopian, or to the woody districts of Mozambique where the fauna has more of a West or South African character.
Mammalia.—The only forms of Mammalia peculiar to this sub-region are Theropithecus, one of the Cynopithecidæ confined to Abyssinia; Petrodromus and Rhynchocyon, belonging to the insectivorous Macroscelididæ, have only been found in Mozambique; the Antelopine genus Neotragus, from Abyssinia southward; Saccostomus and Pelomys genera of Muridæ inhabiting Mozambique; Heterocephalus from Abyssinia, and Heliophobius from Mozambique, belonging to the Spalacidæ; and Pectinator from Abyssinia, belonging to the Octodontidæ. Cynocephalus, Rhinoceros, Camelopardalis, and antelopes of the genera Oryx, Cervicapra, Kobus, Nanotragus, Cephalophus, Hippotragus, Alcephalus, and Catoblepas, are characteristic; as well as Felis, Hyæna, and numerous civets and ichneumons.