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region, and it suggests some curious speculations as to the former history of that region, a subject which must be deferred to the latter part of this chapter. In none of the other great tropical regions does it occur, that the largest portion of their area, although swarming with life, yet possesses hardly any distinctive features except the absence of numerous types characteristic of the other sub-regions.
Plate IV.--Illustrating the Zoology of East Africa.—Although this sub-region has so little speciality, it is that which abounds most in large animals, and is, perhaps, the best representative of Africa as regards zoology. Some of the most distinctive of African animals range over the whole of it, and as, from recent explorations, many parts of this wide area have been made known to the reading public, we devote one of our plates to illustrate the especially African forms of life that here abound. The antelopes represented are the koodoo (Tragelaphus strepsiceros) one of the handsomest of the family, which ranges over all the highlands of Africa from Abyssinia to the southern districts. To the left is the aardvark, or earth pig, of North Eastern Africa (Orycteropus æthiopicus) which, to the north of the equator in East Africa, represents the allied species of the Cape of Good Hope. These Edentata are probably remnants of the ancient fauna of Africa, when it was completely isolated from the northern continents and few of the higher types had been introduced. The large bird in the foreground is the secretary-bird, or serpent-killer (Serpentarius reptilivorus), which has affinities both for the birdsof-prey and the waders. It is common over almost all the open country of Africa, destroying and feeding on the most venomous serpents. The bird on the wing is the red-billed promerops (Irrisor erythrorhynchus), a handsome bird with glossy plumage and coral-red bill. It is allied to the hoopoes, and feeds on insects which it hunts for among the branches of trees. This species also ranges over a large part of east and central Africa to near the Cape of Good Hope. Other species are found in the west; and the genus, which forms a distinct family, Irrisoridæ, is one of the best marked Ethiopian types of birds. In the distance is a rhinoceros, now one of the characteristic features of African
zoology, though there is reason to believe that it is a comparatively recent intruder into the country.
II. The West-African Sub-region. This may be defined as the equatorial-forest sub-region, since it comprises all that portion of Africa, from the west coast inland, over which the great equatorial forests prevail more or less uninterruptedly. These commence to the south of the Gambia River, and extend eastwards in a line roughly parallel to the southern margin of the great desert, as far as the sources of the upper Nile and the mountains forming the western boundary of the basin of the great lakes; and southward to that high but marshy forest-country in which Livingstone was travelling at the time of his death. Its southern limits are undetermined, but are probably somewhere about the parallel of 11° S. Latitude.
This extensive and luxuriant district has only been explored zoologically in the neighbourhood of the West coast. Much, no doubt, remains to be done in the interior, yet its main features are sufficiently well known, and most of its characteristic types of animal life have, no doubt, been discovered,
Mammalia.-Several very important groups of mammals are peculiar to this sub-region. Most prominent are the great anthropoid apes—the gorilla and the chimpanzee-forming the genus Troglodytes ; and monkeys of the genera Myiopithecus and Cercocebus. Two remarkable forms of lemurs, Perodicticus and Arctocebus, are also peculiar to West Africa. Among the Insectivora is Potamogale, a semi-aquatic animal, forming a distinct family; and three peculiar genera of civets (Viverridæ) have been described. Hyomoschus, a small, deer-like animal, belongs to the Tragulidæ, or chevrotains, a family otherwise
1 Dr. Schweinfurth has accurately determined the limits of the sub-region at the point where he crossed the watershed between the Nile tributaries and those of the Shari, in 44° N. Lat. and 28}° E. Long. He describes a sudden change in the character of the vegetation, which to the southward of this point assumes a West-African character. Here also the chimpanzee and grey parrot first appear, and certain species of plants only known elsewhere in Western Africa.
confined to the Oriental region; and in the squirrel family is a curious genus, Anomalurus, which resembles the flying squirrels of other parts of the world, without being directly allied to them.
Birds. In this class we find a larger proportionate number of peculiar forms. Hypergerus and Alethe, belonging to the Timaliidæ, or babblers, are perhaps allied to Malayan groups; Parinia, a peculiar form of tit, is found only in Prince's Island; I.conotus is an abundant and characteristic form of Pycnonotidæ; Fraseria, Hypodes, Cuphopterus, and Chaunonotus, are peculiar genera of shrikes; Picathartes is one of the many strange forms of the crow family; Cinnyricinclus is a peculiar genus of sunbirds ; Pholidornis is supposed to belong to the Oriental Dicæidæ, or flower-peckers; Waldenia is a recently-described new form of swallow; Ligurnus, a finch, Spermospiga, a weaver bird, and Onychognathus a starling, are also peculiar West African genera. Coming to the Picariæ we have Verreauxia, a peculiar woodpecker ; three peculiar genera of barbets (Megalæmidæ); the typical plantain-eaters (Musophaga); Myioceyx, a peculiar genus of kingfishers; while Berenicornis is a genus of crested hornbills, only found elsewhere in Malaya. The grey parrots, of the genus Psittacus, are confined to this sub-region, as are two peculiar genera of partridges, and three of guineafowl. We have also here a species of Pitta, one of the Oriental family of ground-thrushes; and the Oriental paroquets, Palæornis, are found here as well as in Abyssinia and the Mascarene Islands.
We thus find, both in the Mammalia and birds of West Africa, a special Oriental or even Malayan element not present in the other parts of tropical Africa, although appearing again in Madagascar. In the Mammalia it is represented by the anthropoid apes; by Colobus allied to Semnopithecus, and by Cercocebus allied to Macacus ; and especially by a form of the Malayan family of chevrotains (Tragulidæ). The Malayan genus of otters, Aonyx, is also said to occur in West and South Africa. In birds we have special Oriental and Malayan affinities in Alethe, Pholidornis, Berenicornis, Pitta, and Palæornis; while the Oriental genus Treron has a wide range in Africa. We shall
endeavour to ascertain the meaning of this special relation at a subsequent stage of our inquiries.
Plate V.–River Scene in West Africa, with Characteristic Animals.—Our artist has here well represented the luxuriance and beauty of a tropical forest; and the whole scene is such as might be witnessed on the banks of one of the rivers of equatorial West Africa. On the right we see a red river-hog (Potamochærus penicillatus), one of the handsomest of the swine family, and highly characteristic of the West African sub-region. In a tree overhead is the potto (Perodicticus potto), one of the curious forms of lemur confined to West Africa. On the left is the remarkable Potamogale velox, first discovered by Du Chaillu,-an Insectivorous animal, with the form and habits of an otter. On the other side of the river are seen a pair of gorillas (Troglodytes gorilla), the largest of the anthropoid apes.
The bird on the wing is the Whydah finch (Vidua paradisea), remarkable for the enormous plumes with which the tail of the male bird is decorated during the breeding season. The crested bird overhead is one of the beautiful green touracos (Turacus macrorhynchus), belonging to the Musophagidæ, or plantain-eaters, a family wholly African, and most abundant in the western sub-region.
Reptiles. In this class we find a large number of peculiar forms ; 13 genera of snakes, 3 of lizards, and 2 of tortoises being confined to the sub-region. The snakes are Pariaspis, Elapops, and Prosymna (Calamariidæ), Rhamnophis, Herpetethiops, and Grayia (Colubridæ), Neusterophis and Limnophis (Homalopsidæ), Simocephalus and Holurophis (Lycodontidæ); Pelophilus (Pythonidæ); Elapsoidea (Elapidæ); and Atheris (Viperidæ). The lizards are Dalophia (Lepidosternidæ); Otosaurus (Scincidæ); Psilodactylus (Geckotidæ). The tortoises, Cinyvis (Testudinidæ) and Tetrathyra (Trionichidæ).
Amphibia.–Of Amphibia, there are 2 peculiar genera of treefrogs, Hylambatis and Hemimantis, belonging to the Polypedatidae