Page:EB1911 - Volume 28.djvu/1036

TERRESTRIAL] distinct. The Prosimiae, or lemuroids, include the galagos (Galago) and pottos (Perodictycus), of which the latter are akin to the Oriental loriscs, while the former are quite distinct from the Malagasy lemurs. Among the Carnivora, the aard-wolf (Proteles), the hunting-dog (Lycaon) and the long-eared fox (Otocyon) are peculiar generic types, as are several forms of mungooses (Herpestinae); while the spotted hyaena forms a subgenus by itself. The bear-family (Ursidae), on the other hand, is totally absent. In the great ungulate order the African elephant is widely sundered from its Asiatic cousin, as are the two species of rhinoceros from their representatives in the Oriental region; indeed each group is sub-generically distinct. The hyraxes, forming the suborder Hyracoidea, are, with the exception of a single outlying Syrian species, confined to Ethiopia. Zebras and true wild asses are likewise peculiar to the region. More remarkable is the extraordinary number of peculiar genera of antelopes, a few of which range, however, into North Africa, Syria and Arabia; the African buffaloes are markedly different from those of Asia; and sheep and goats are absent from the region, with the exception of intruding into it to some extent in the mountains of the Sudan and Abyssinia. The giraffe-family (Giraffidae), as represented by giraffes (Griraffa) and the okapi (Ocapia), is absolutely confined to this region, from which the deer-tribe (Cervidae) is completely absent. Chevrotains, or mouse-deer, are represented by the peculiar genus Dorcatherium (or Hyomoschus); in the pigs the wart-hogs (Phacochoerus), forest-hogs (Hylochoerus), and the bush-pigs (subgenus Potamochoerus), with the exception of one Malagasy species, are now unknown elsewhere, as are also hippopotamuses. Rodents include a number of peculiar types, among which may be noticed the scaly-tailed squirrels (Anomaluridae), the jumping-hares (Pedetes), the strand-moles (Bathyergidae), the crested-rats (Lophiomys), and the cane-rats (Thryonomys, or Aulacodus); the last being nearly allied to South American forms. In the Insectivora, moles (Talpidae) are absent, the jumping-shrews (Macroscelididae) are solely African, although ranging north of the Sahara, while the golden moles (Chrysochloridae) and the Potamogalidae are exclusively Ethio pian. Lastly, the ant-bears, or aard-varks (Orycteropodidae), represent a suborder of the Edentata unknown elsewhere; while the African pangolins (Manidae) differ markedly from their Oriental kindred.

The Ethiopian birds are less peculiar. The ostrich (Struthio) ranges, in suitable localities, all over the region, thus entering the Mediterranean transition-region in the north. The guinea-fowls (Numidinae) form a subfamily confined to Ethiopia and Madagascar, where true pheasants are unknown. Other peculiar types are plantain-eaters (Musophagidae), colics (Coliidae), wood-hoopoes (Irrisoridae), barbets (Megalaemidae), ground-hornbills (Bucorvus), secretary-birds (Serpentariidae), glossy starlings (Lamprotornis), ox-peckers (Buphaga), the genera Laniarius and Telephorus, as well as a number of others, all of which are unknown in Madagascar. In addition to true pheasants, wrens (Troglodytidae) and water-ousels (Cinclidae) are unknown in the Ethiopian region.

Apart from the widespread Trionychoidea (of which there are two genera peculiar to the region), the Ethiopian fresh-water tortoises belong to the section Pleurodira; the two genera Pelomedusa and Sternothaerus being common to Africa and Madagascar, and unknown elsewhere. The Amphisbaenidae are common to Neogaea and Ethiopia, to the exclusion of Madagascar; but the Gerrnosauridae and Zonuridae, on the other hand, are restricted to the present region and Madagascar, which also form the headquarters of chameleons. In contrast to the latter community is the absence in Madagascar of Agamidae and Varanidae, which are common in Ethiopia. The absence of slow-worms and their kindred (Anguidae) is a marked negative feature of the present region. As regards batrachians, the region has no salamanders or other tailed forms, but, in common with India, possesses caecilians (Apoda); while it shares the group of tongueless toads (Aglossa) with Neogaea, its peculiar family being the Xenopodidae, in contra-distinction to the South American Pipidae. The Pelobatidae are absent, and true toads are few, but frogs are abundant.

Among fishes, Africa south of the Sahara possesses a number of peculiar types. With Neogaea it shares the possession of the typical lung-fishes (Lepidosirenidae), while it is the habitat of the species of bichir (Polypterus) and Calamoichthys, the sole survivors of the ancient group of fringe-finned ganoids (Crossopterygii). The other families peculiar to Ethiopia are the Mormyridae (proboscis-fishes), Pantodontidae, and Phractolaemidae; the two latter being represented only by a single species each. The Notopteridae, Ophiocephalidae, Anabantidae, Osphromenidae and Mastacembelidae are common to Ethiopia and the Oriental region. In addition to the Lepidosirenidae, the Characinidae are peculiar to this region and Neogaea. The Cichlidae occur in Madagascar, Ethiopia, the Oriental region and Neogaea; and the Osteoglossidae are common to the last three of these regions, as well as Australia, while the Nandidae are Ethiopian, Oriental and Neotropical. On the whole, the affinities of the fish-fauna of Ethiopia are nearest to that of the Oriental region, and, secondly, to that of South America.

Although invertebrates do not come within the scope of the

present article, it may be mentioned that Ethiopia is remarkable for the total absence of fresh-water cray-fishes.

As regards its past history, Ethiopian Africa was in connexion with India during the Triassic and Jurassic periods, the two areas collectively forming "Gondwanaland," which doubtless constituted a portion of the equatorial land-belt referred to as existing during the epochs in question. Gondwanaland was the home of a large section of the anomodont reptiles from which mammals have sprung; and it is quite probable that the evolution of the latter group took place within the present area. Between the Trias and the Eocene little or nothing is known of the vertebrate palaeontology of Ethiopia; and in Egypt there is also a long gap between the lower Miocene and certain Pliocene beds in the Wadi Natrun. The Tertiary deposits of southern Europe and northern India indicate, however, that Ethiopian Africa was in free communication with these countries during the upper Miocene and Pliocene epochs. There occur, for instance, either in south-eastern Asia or southern Europe, or both, during the latter period numerous genera of antelopes now restricted to Ethiopia, as well as giraffes, okapi-like ruminants (Palaeotragus), elephants and rhinoceroses of an African type, probably zebras, hippopotamuses, baboons, chimpanzees and ostriches. Owing to imperfect knowledge of Pliocene Africa, it is impossible to say whether these types were first developed in Ethiopia or to the north-east, and consequently whether or not Professor Huxley was right in his theory that the modern higher mammalian fauna of Ethiopia came from the north. It has, however, been suggested that while the Bovidae are an autochthonous Ethiopian group, the Cervidae originated in either the Holarctic or the Oriental region; a theory which if confirmed will materially aid in explaining the absence of the latter group from Ethiopia. It is supported to some extent by the fact that we are acquainted with primitive ancestral deer in the European Tertiary, while the ancestors of the Bovidae are at present unknown. Whatever be the truth on this point, it is manifest that whether the middle Tertiary Bovidae migrated from Ethiopia to Asia or in the opposite direction, there must have been some cause which barred the entrance by the same route into the latter area of all members of the deer-tribe (as well as bears). It should be added that although the ancestral Proboscidea were Ethiopian, the passage from the mastodons into the true elephants appears to have taken place in Asia; a circumstance which would imply the Asiatic origin of the African elephant.

The evidence in favour of the continuation of the Mesozoic land-bridge between Ethiopia and Neogaea has been discussed under the heading of the latter area. If the arguments in favour of such a connexion are valid, it is to the old mammal fauna of Ethiopia that we must probably look for the progenitors of the Santa Cruz fauna of Patagonia. Very noteworthy is the alleged occurrence of remains of primitive armadillos in the Oligocene beds of southern Europe in association with those of pangolins and aard-varks; since, if these fossils be rightly determined, there at once arises the probability of Africa having been the original home of the entire Edentate order.

In the case of an island lying so close to the African continent as does Madagascar the natural expectation would be that its fauna should be intimately related to that of the former. As a matter of fact—in the case of mammals and birds, at any rate—it is much more distinct from the Ethiopian fauna than is the latter from the fauna of either the Oriental or the Holarctic region. The evidence—from the above-mentioned groups—in favour of recognizing a distinct Malagasy region is in fact positively overwhelming, while it is also supported in some degree by the distribution of groups other than those named. In place of the Ethiopian assemblage of apes, monkeys, baboons, galagos and pottos, Madagascar (together with the Comoro islands) possesses an absolutely unique fauna of lemurs, constituting the family Lemuridae, which, as now understood, is confined to this island, where it is represented by the three subfamily-groups of sifakas (Indrisinae), true lemurs (Lemurinae), and aye-ayes (Chiromyinae). All these animals agree with one another in the characters of the tympanic region of the skull; thereby differing from the African and Oriental Prosimiae, but agreeing with the European Oligocene Adapis, which must apparently be regarded as the ancestral form. This is a striking confirmation of the theory advanced many years ago by Huxley that Madagascar received its lemuroid fauna from Europe at a very early date, since which time, at any rate, it has been isolated from Africa. Some of the Pleistocene Malagasy lemurs were much larger than any of the living forms, rivalling in this respect a chimpanzee. The Carnivora are represented only by a small number of species, mostly referable to peculiar genera, of Viverridae, among which the fossa (Cryptoprocta) is the largest. In the ungulates there are only two extinct species of hippopotamus and a living bush-pig, the ancestors of all three of which probably crossed the Mozambique channel by swimming; and Edentata are equally conspicuous by their absence. Insectivora, on the other hand, are represented by the tenrecs (Centetidae), with numerous generic types, whose nearest relatives