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The following table shows the approximate number of genera of the West African Sub-region in each order and their distribution:
This Sub-region, when extended so as to include the whole country as far north as Angola on the west, and up to the Tana river on the east, is on the whole, after the Malagasy, the most distinct of the four Sub-regions, since it possesses nineteen endemic genera out of a total of ninety
Furthermore, its area exhibits a greater range of temperature and humidity than the other Sub-regions, for, while in Natal and Mozambique tropical forest-conditions prevail, giving the fauna a certain resemblance to that of West Africa, in Cape Colony itself a temperate and fairly dry climate is found. Again, in Namaqua-land, to the north-west of Cape Colony, we meet with an open, dry, hot, desert country, the conditions of which closely approximate to those of the Saharan Sub-region. The distinctness of this Sub-region, apart from the mammals, is strongly marked by a very remarkable Flora, as well as by the exclusive possession of many forms among the other orders and classes of the animal kingdom. Among the Edentata,
besides the Scaly Ant-eater (Manis), of which one species extends as far south-east as the Transvaal, there is also found the Aardvark (Orycteropus), an animal characteristic of South Africa, though also occurring in East Africa as far north as the upper Nile basin. The relationships of this creature are very obscure, but the recent discovery of remains of a closely allied fossil form in beds of lower Pliocene age in the island of Samos, in the Ægean Sea, shows that the Aardvark, like so many other African animals, has migrated southwards from the Palæarctic Region.
The greater number of the genera to which the numerous Antelopes of the Cape Sub-region belong, extend northwards into the Saharan and even into the West African Sub-region, although the species of the Cape Sub-region are in many cases distinct.
Among the distinct species may be mentioned the Hartebeest (Bubalis caama), the Spring-bok (Antidorcas euchore), and the Sable Antelope (Hippotragus niger). The two Gnus (Connochætes) and the Pallah (Æryceros) are confined to this Sub-region. To the portion of this Sub-region south of the Zambesi are restricted two of the African horses, the Quagga (Equus quagga), now said to be extinct, and the Mountain Zebra (Equus zebra), which is fast approaching the same condition. But Burchell's Zebra (Equus burchelli), under various slight modifications, occurs in suitable localities throughout the whole Sub-region.
The White or Square-lipped Rhinoceros (Rhinoceros simus), which now only exists in two small districts of Mashonaland and Zululand, was formerly abundant in the Cape Colony and the Transvaal, but has never been met with north of the Zambesi.
Five out of the eighteen genera of Rodents found in this Sub-region are endemic. Two of these belong to the Mouse-family (Muridæ), and two more to a burrowing family (Spalacidæ); the fifth (Petromys) belongs to the family Octodontidæ, which the Ethiopian shares with the Neotropical Region.
The South African Sub-region, however, is especially remarkable for the large number of peculiar genera of Carnivora. Five of these genera have been formed for the reception of a number of small animals allied to the Indian Mongoose. Another, for which a separate family has been created, contains only the Aard-wolf (Proteles), an animal nearly allied to the hyenas, but with very small and rudimentary teeth, and a heavy mane of long hair. It is nocturnal, and feeds principally on carrion, being too weak to attack other living animals. The Otocyon, or Cape Hunting-dog, which constitutes another peculiar genus, is remarkable for having a greater number of molar teeth than any other mammal. Owing to this, it has been regarded by Professor Huxley as the most primitive of all existing members of its Family. Out of the six genera of Insectivora found in this Sub-region three are endemic. Of these the most interesting is the genus Chrysochloris, which forms a distinct Family, and comprises no less than eight species. These animals are sometimes known as “Golden Moles,” owing to the brilliant metallic lustre of their fur. They are in some respects allied to the Centetidæ, a family mentioned above as confined to Madagascar; but they are modified for a burrowing life, and externally resemble the Moles. Neither of the two remaining Orders, the Bats and the Monkeys, is represented by peculiar genera in the Cape Sub-region. This, however, is quite
what one would expect, as members of these two Orders are essentially forest-loving in their habits, and this Subregion consists chiefly of sparsely wooded and arid districts.
On the whole, therefore, the Cape Sub-region will be found to be characterized, as compared with other parts of Africa, by the exclusive possession of the following forms:
1. Connochætes (the Gnu), Pelea (the Rhébok) and #pyceros (the Pallah) among the Antelopes.
2. Pachyuromys and Mystromys, genera of Muridæ ; Bathyergus and Myoscalops, genera of the burrowing Spalacidæ; Petromys of the Octodontidæ, among the Rodents.
3. Five genera of Mongooses, belonging to the family of Viverridæ; Proteles, the only representative of the family Protelidæ ; Otocyon (the Cape Hunting-dog); and Poecilogale (a small weasel), among the Carnivora.
4. Rhynchocyon, of the Macroscelidæ; Myosorex (a Shrew); and the Chrysochloride (Golden Moles), among the Insectivora.
The following table, showing the distribution of the genera, is constructed on the same plan as that of the other Sub-regions.
SECTION VII.-THE SAHARAN SUB-REGION
The Saharan Sub-region, as its name implies, is essentially a dry and desert district. As here regarded, in addition to the Sahara proper, it includes the southern part of Arabia and Somaliland, both of which are distinctly arid countries. The only part of the Sub-region where there is much rainfall is in the Abyssinian highlands and the country surrounding such isolated mountains as Kenia. In consequence of these facts, and also in accordance with the fact that the Sub-region is conterminous for so long a distance with the Palæarctic Region, the number of endemic genera of the Saharan Sub-region is extremely small, being only seven out of a total of eighty-five-that is, 8 per cent. as compared with 21 per cent. in the Cape, and 15 per cent. in the West African Sub-region.
Of recent years a considerable number of new forms, especially of Antelopes, have been obtained from Somaliland, a country which, up to a few years ago, was quite unknown, and it is quite possible that eventually the “unknown Horn of Africa” will be found to possess a Fauna sufficiently distinct from the rest of the continent to be separated as another Sub-region. But for the present, until our knowledge is widened a little more, it will be best to keep Somaliland in the Saharan Sub-region.
The most characteristic feature of the Sub-region is, perhaps, the large numbers of Antelopes. These, as a rule, are specifically distinct from those of the Cape Subregion. Among them may be mentioned Swayne's Hartebeeste (Bubalis swaynei), Hunter's Bontebok (Damaliscus hunteri), three species of Oryx (0. beisa from Abyssinia