ETHIOPIAN REGION
THE ETHIOPIAN REGION.
This is one of the best defined of the great zoological regions, consisting of tropical and South Africa, to which must be added tropical Arabia, Madagascar, and a few other islands, all popularly known as African. Some naturalists would extend the region northwards to the Atlas Mountains and include the whole of the Sahara; but the animal life of the northern part of that great desert seems more akin to the Palæarctic fauna of North Africa. The Sahara is really a debatable land which has been peopled from both regions; and until we know more of the natural history of the great plateaus which rise like islands in the waste of sand, it will be safer to make the provisional boundary line at or near the tropic, thus giving the northern half to the Palæarctic, the southern to the Ethiopian region. The same line may be continued across Arabia.
With our present imperfect knowledge of the interior of Africa, only three great continental sub-regions can be well defined. The open pasture lands of interior tropical Africa are wonderfully uniform in their productions; a great number of species ranging from Senegal to Abyssinia and thence to the Zambesi, while almost all the commoner African genera extend over the whole of this area. Almost all this extensive tract of country is a moderately elevated plateau, with a hot and dry climate, and characterised by a grassy vegetation interspersed with patches of forest. This forms our first or East African sub-region. The whole of the west coast from the south side of the Gambia River to about 10° or 12° south latitude, is a verydifferent kind of country; being almost wholly dense forests where not cleared by man, and having the hot moist uniform climate, and perennial luxuriance of vegetation, which characterise the great equatorial belt of forest all round the globe. This forest country extends to an unknown distance inland, but it was found, with its features well marked, by Dr. Schweinfurth directly he crossed the south-western watershed of the Nile; and far to the south we find it again unmistakably indicated, in the excessively moist forest country about the head waters of the Congo, where the heroic Livingstone met his death. In this forest district many of the more remarkable African types are alone found, and its productions occasionally present us with curious similarities to those of the far removed South American or Malayan forests. This is our second or West African sub-region.
Extra-tropical South Africa possesses features of its own, quite distinct from those of both the preceding regions (although it has also much in common with the first). Its vegetation is known to be one of the richest, most peculiar, and most remarkable on the globe; and in its zoology it has a speciality, similar in kind but less in degree, which renders it both natural and convenient to separate it as our third, or South African sub-region. Its limits are not very clearly ascertained, but it is probably bounded by the Kalahari desert on the north-west, and by the Limpopo Valley, or the mountain range beyond, on the north-east, although some of its peculiar forms extend to Mozambique. There remains the great Island of Madagascar, one of the most isolated and most interesting on the globe, as regards its animal productions; and to this must be added, the smaller islands of Bourbon, Mauritius and Rodriguez, the Seychelles and the Comoro Islands, forming together the Mascarene Islands,—the whole constituting our fourth sub-region.
Zoological Characteristics of the Ethiopian Region.—We have now to consider briefly, what are the peculiarities and characteristics of the Ethiopian Region as a whole,—those which give it its distinctive features and broadly separate it from the other primary zoological regions.
Mammalia.—This region has 9 peculiar families of mammalia. Chiromyidæ (containing the aye-aye); Potamogalidæ and Chrysochloridæ (Insectivora); Cryptoproctidæ and Protelidae (Carnivora); Hippopotamidæ and Camelopardalidæ (Ungulata); and Orycteropodidæ (Edentata). Besides these it possesses 7 peculiar genera of apes,Troglodytes,Colobus,Myiopithecus,Cercopithecus,Cercocebus,Theropithecus, andCynocephalus; 2 sub-families of lemurs containing 6 genera, confined to Madagascar, with 3 genera of two other sub-families confined to the continent; of Insectivora a family, Centetidæ, with 5 genera, peculiar to Madagascar, and the generaPetrodromusandRhynchocyonbelonging to the Macroscelididæ, or elephant-shrews, restricted to the continent; numerous peculiar genera or sub-genera of civets;LycaonandMegalotis, remarkable genera of Canidæ;Ictonyx, the zorilla, a genus allied to the weasels; 13 peculiar genera of Muridæ;Pectinator, a genus of the South American family Octodontidæ; and 2 genera of the South American Echimyidæ or spiny rats. Of abundant and characteristic groups it possessesMacroscelides,Felis,Hyæna,Hyrax,Rhinoceros, andElephas, as well as several species of zebra and a great variety of antelopes.
The great speciality indicated by these numerous peculiar families and genera, is still farther increased by the absence of certain groups dominant in the Old-World continent, an absence which we can only account for by the persistence, through long epochs, of barriers isolating the greater part of Africa from the rest of the world. These groups are, Ursidæ, the bears; Talpidæ the moles; Camelidæ, the camels; Cervidæ, the deer; Caprinæ, the goats and sheep; and the generaBos(wild ox); andSus(wild boar). Combining these striking deficiencies, with the no less striking peculiarities above enumerated, it seems hardly possible to have a region more sharply divided from the rest of the globe than this is, by its whole assemblage of mammalia.
Birds.—In birds the Ethiopian region is by no means so strikingly peculiar, many of these having been able to pass the ancient barriers which so long limited the range of mammalia.It is, however, sufficiently rich, possessing 54 families of land birds, besides a few genera whose position is not well ascertained, and which may constitute distinct families. Of these 6 are peculiar, Musophagidæ (the plantain eaters); Coliidæ (the colies); Leptosomidæ, allied to the cuckoos; Irrisoridæ, allied to the hoopoes; and Serpentaridæ, allied to the hawks. Only one Passerine family is peculiar—Paictidæ, while most of the other tropical regions possess several; butEurycerosandBuphaga, here classed with the Sturnidæ, ought, perhaps, to form two more. It has, however, many peculiar genera, especially among the fruit-thrushes, Pycnonotidæ; flycatchers, Muscicapidæ; shrikes, Lanidæ; crows, Corvidæ; starlings, Sturnidæ; and weaver-birds, Ploceidæ; the latter family being very characteristic of the region. It is also rich in barbets, Megalæmidæ (7 peculiar genera); cuckoos, Cuculidæ; rollers, Coraciidæ; bee-eaters, Meropidæ; hornbills, Bucerotidæ; and goat-suckers, Caprimulgidæ. It is poor in parrots and rather so in pigeons; but it abounds inPteroclesandFrancolinus, genera of Gallinæ, and possesses 4 genera of the peculiar group of the guinea-fowls, forming part of the pheasant family. It abounds in vultures, eagles, and other birds of prey, among which is the anomalous genusSerpentarius, the secretary-bird, constituting a distinct family. Many of the most remarkable forms are confined to Madagascar and the adjacent islands, and will be noticed in our account of that sub-region.
Reptiles.—Of the reptiles there are 4 peculiar Ethiopian families;—3 of snakes, Rachiodontidæ, Dendraspidæ, and Atractaspidæ and 1 of lizards, Chamæsauridæ.
Psammophidæ (desert snakes) are abundant, as are Lycodontidæ (fanged ground-snakes), and Viperidæ (vipers). The following genera of snakes are peculiar or highly characteristic:—Leptorhynchus,Rhamnophis,HerpetethiopsandGrayia(Colubridæ);HopsidrophisandBucephalus(Dendrophidæ);Langalia(Dryophidæ);Pythonodipsas(Dipsadidæ);Boedon,Lycophidion,Holuropholis,SimocephalusandLamprophis(Lycodontidæ);HortuliaandSanzinia(Pythonidæ);Cyrptophis,ElapsoideaandPœcilophis(Elapidæ); andAtheris(Viperidæ). The following generaof lizards are the most characteristic:—Monotrophis(Lepidosternidæ);Cordylus,Pseudocordylus,Platysaurus,Cordylosaurus,Pleurostichus,SaurophisandZonurus(Zonuridæ);Sphænops,Scelotes,SphænocephalusandSepsina(Sepidæ);Pachydactylus(Geckotidæ);Agama(Agamidæ); andChameleon(Chameleonidæ). Of tortoises,Cynyxis,PyxisandChersina(Testudinidæ), andCycloderma(Trionychidæ) are the most characteristic.
Amphibia.—Of the 9 families of amphibia there is only 1 peculiar, the Dactylethridæ, a group of toads; but the Alytidæ, a family of frogs, are abundant.
Fresh-water Fish.—Of the 14 families of fresh-water fishes 3 are peculiar: Mormyridæ and Gymnarchidæ, small groups not far removed from the pikes; and Polypteridæ, a small group of ganoid fishes allied to the gar-pikes (Lepidosteidæ) of North America.
Summary of Ethiopian Vertebrates.—Combining the results here indicated and set forth in greater detail in the tables of distribution, we find that the Ethiopian region possesses examples of 44 families of mammalia, 72 of birds, 35 of reptiles, 9 of amphibia, and 15 of fresh-water fishes. It has 23 (or perhaps 25) families of Vertebrata altogether peculiar to it out of a total of 175 families, or almost exactly one-eighth of the whole. Out of 142 genera of mammalia found within the region, 90 are peculiar to it; a proportion not much short of two-thirds. Of land birds there are 294 genera, of which 179 are peculiar; giving a proportion of a little less than three-fifths.
Compared with the Oriental region this shows a considerably larger amount of speciality under all the heads; but the superiority is mainly due to the wonderful and isolated fauna of Madagascar, to which the Oriental region has nothing comparable. Without this the regions would be nearly equal.
Insects: Lepidoptera.—11 out of the 16 families of butterflies have representatives in Africa, but none are peculiar. Acræidæ is one of the most characteristic families, and thereare many interesting forms of Nymphalidæ, Lycænidæ, and Papilionidæ. The peculiar or characteristic forms areAmauris(Danaidæ);Gnophodes,Leptoneura,Bicyclus,HeteropsisandCœnyra(Satyridæ);Acræa(Acræidæ);Lachnoptera,Precis,Salamis,Crenis,Godartia,Amphidema,Pseudacræa,Catuna,Euryphene,Romalæosoma,Hamanumida,Aterica,Harma,Meneris,Charaxes, andPhilognoma(Nymphalidæ);Pentila,Liptena,Durbania,Zeritis,Capys,Phytala,Epitola,HewitsoniaandDeloneura(Lycænidæ);Pseudopontia,Idmais,Teracolus,Callosune(Pieridæ);Abantis,CeratrichiaandCaprona(Hesperidæ). The total number of species known is about 750; which is very poor for an extensive tropical region, but this is not to be wondered at when the nature of much of the country is considered. It is also, no doubt, partly due to our comparative ignorance of the great equatorial forest district, which is the only part likely to be very productive in this order of insects.
Coleoptera.—In our first representative family, Cicindelidæ or tiger-beetles, the Ethiopian region is rather rich, having 13 genera, 11 of which are peculiar to it; and among these are such remarkable forms asManticora,MyrmecopteraandDromica; withMegacephala, a genus only found elsewhere in Australia and South America.
In Carabidæ or carnivorous ground beetles, there are about 75 peculiar genera. Among the most characteristic areAnthia,Polyrhina,GraphipterusandPiezia, which are almost all peculiar; whileOrthogonius,Hexagonia,Macrochilus,Thyreopterus,Eudema, andAbacetusare common to this and the Oriental region; andHypolithusto the Neotropical.
Out of 27 genera of Buprestidæ, or metallic beetles, only 6 are peculiar to the region, one of the most remarkable beingPolybothrus, confined to Madagascar.SternoceraandChrysochroaare characteristic of this region and the Oriental; it hasJulodisin common with the Mediterranean sub-region, andBelionotawith the Malayan.
The region is not rich in Lucanidæ, or stag-beetles, possessing only 10 genera, 7 of which are peculiar, but most of themconsist of single species. The other three genera,Cladognathus,Nigidius, andFigulus, are the most characteristic, though all have a tolerably wide range in the Old World.
In the elegant Cetoniidæ, or rose-chafers, this region stands preeminent, possessing 76 genera, 64 of which are peculiar to it. The others are chiefly Oriental, exceptOxythræawhich is European, andStethodesmawhich is Neotropical. Preeminent in size and beauty isGoliathus, comprising perhaps the most bulky of all highly-coloured beetles. Other large and characteristic genera areCeratorhina,Ischnostoma,Anochilia,Diplognatha,Agenius, and many others of less extent.
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,Tithoesis a characteristic Ethiopian genus. A few species of the American generaParandraandMallodonoccur here, while the North Temperate genusPrionusis only found in Madagascar. Among Cerambycidæ,Promecesis the most characteristic. The American generaOemeandCyrtomerusoccur; whileHomalachnusandPhilagathesare Malayan, andLeptoceraoccurs only in Madagascar, Ceylon, Austro-Malaya, and Australia. The Lamiidæ are very fine;Sternotomis,Tragocephala,Ceroplesis,Phryncta,Volumnia, andNitocris, being very abundant and characteristic. Most of the non-peculiar genera of this family are Oriental, butSpalacopsisandAcanthoderesare American, whileTetraglenesandSchœniontahave 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 ofAchatina, some of the species being the largest land-shellsknown.Buliminus,Stenogyra, andPupaare characteristic genera.Bulimusis 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'sManual(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 amoderate 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, asMungos fasciatusandPhacochœrus 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 ofspecies, 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 areTheropithecus, one of the Cynopithecidæ confined to Abyssinia;PetrodromusandRhynchocyon, belonging to the insectivorous Macroscelididæ, have only been found in Mozambique; the Antelopine genusNeotragus, from Abyssinia southward;SaccostomusandPelomysgenera of Muridæ inhabiting Mozambique;Heterocephalusfrom Abyssinia, andHeliophobiusfrom Mozambique, belonging to the Spalacidæ; andPectinatorfrom Abyssinia, belonging to the Octodontidæ.Cynocephalus,Rhinoceros,Camelopardalis, and antelopes of the generaOryx,Cervicapra,Kobus,Nanotragus,Cephalophus,Hippotragus,Alcephalus, andCatoblepas, are characteristic; as well asFelis,Hyæna, and numerous civets and ichneumons.
Birds.—Peculiar forms of birds are hardly to be found here; we only meet with two—Hypocolius, a genus of shrikes in Abyssinia; andBalæniceps, the great boat-billed heron of the Upper Nile. Yet throughout the country birds are abundant, and most of the typical Ethiopian forms are well represented.
Reptiles.—Of reptiles, the only peculiar forms recorded areXenocalamus, a genus of snakes, belonging to the Calamariidæ; andPythonodipsas, one of the Dipsadidæ, both from the Zambesi; and among lizards,Pisturus, one of the Geckotidæ, from Abyssinia.
Amphibia and Fishes.—There are no peculiar forms of amphibia or of fresh-water fishes.
Insects.—Insects are almost equally unproductive of peculiar forms. Among butterflies we haveAbantis, one of the Hesperidæ, from Mozambique; and in Coleoptera, 2 genera of Cicindelidæ, 8 of Carabidæ, 1 or 2 of Cetoniidæ, and about half-a-dozen of Longicorns: a mere nothing, as we shall see, compared with the hosts of peculiar genera that characterise each of the other sub-regions. Neither do land-shells appear to present any peculiar forms.
The fact that so very few special types characterise the extensive area now under consideration is very noteworthy. It justifies us in uniting this large and widespread tract of country as forming essentially but one sub-division of the great Ethiopian 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.
CHARACTERISTIC ANIMALS OF EAST AFRICA.
CHARACTERISTIC ANIMALS OF EAST AFRICA.
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 birds-of-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 Africanzoology, 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.[10]
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 genusTroglodytes; and monkeys of the generaMyiopithecusandCercocebus. Two remarkable forms of lemurs,PerodicticusandArctocebus, are also peculiar to West Africa. Among the Insectivora isPotamogale, 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 otherwiseconfined 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.HypergerusandAlethe, 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;Ixonotusis an abundant and characteristic form of Pycnonotidæ;Fraseria,Hypodes,Cuphopterus, andChaunonotus, are peculiar genera of shrikes;Picathartesis one of the many strange forms of the crow family;Cinnyricinclusis a peculiar genus of sun-birds;Pholidornisis supposed to belong to the Oriental Dicæidæ, or flower-peckers;Waldeniais a recently-described new form of swallow;Ligurnus, a finch,Spermospiga, a weaver bird, andOnychognathusa starling, are also peculiar West African genera. Coming to the Picariæ we haveVerreauxia, a peculiar woodpecker; three peculiar genera of barbets (Megalæmidæ); the typical plantain-eaters (Musophaga);Myioceyx, a peculiar genus of kingfishers; whileBerenicornisis a genus of crested hornbills, only found elsewhere in Malaya. The grey parrots, of the genusPsittacus, are confined to this sub-region, as are two peculiar genera of partridges, and three of guinea-fowl. We have also here a species ofPitta, 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; byColobusallied toSemnopithecus, and byCercocebusallied toMacacus; 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 inAlethe,Pholidornis,Berenicornis,Pitta, andPalæornis;while the Oriental genusTreronhas a wide range in Africa. We shallendeavour 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 (Potamochœrus 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 remarkablePotamogale 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 arePariaspis,Elapops, andProsymna(Calamariidæ),Rhamnophis,Herpetethiops, andGrayia(Colubridæ),NeusterophisandLimnophis(Homalopsidæ),SimocephalusandHolurophis(Lycodontidæ);Pelophilus(Pythonidæ);Elapsoidea(Elapidæ); andAtheris(Viperidæ). The lizards areDalophia(Lepidosternidæ);Otosaurus(Scincidæ);Psilodactylus(Geckotidæ). The tortoises,Cinyxis(Testudinidæ) andTetrathyra(Trionichidæ).
Amphibia.—Of Amphibia, there are 2 peculiar genera of tree-frogs,HylambatisandHemimantis, belonging to the Polypedatidæ.
Plate V.
SCENE IN WEST AFRICA, WITH CHARACTERISTIC ANIMALS.
SCENE IN WEST AFRICA, WITH CHARACTERISTIC ANIMALS.
Here, too, we find some interesting relations with the Oriental region on the one side, and the Neotropical on the other. The snakes of the family Homalopsidæ have a wide range, in America, Europe, and all over the Oriental region, but are confined to West Africa in the Ethiopian region.Dryiophis(Dryiophidæ) andDipsadoboa(Dipsadidæ) on the other hand, are genera of tropical America which occur also in West Africa. The family of lizards, Acontiadæ, are found in West and South Africa, Ceylon, and the Moluccas. The family of toads, Engystomidæ, in West and South Africa and the whole Oriental region; while the Phryniscidæ inhabit tropical Africa and Java.
Insects.—We have here a large number of peculiar genera. There are 10 of butterflies,Lachnoptera,Amphidema, andCatunabelonging to the Nymphalidæ, while four others are Lycænidæ. The genusEuxantheis common to West Africa and Madagascar.
Of Coleoptera there are 53 peculiar genera; 20 are Carabidæ, 2 Lucanidæ, 12 Cetoniidæ, 3 Prionidæ, 16 Cerambycidæ, and 34 Lamiidæ. Besides these there are 4 or 5 genera confined to West Africa and Madagascar.
Land Shells.—West Africa is very rich in land shells, but it does not appear to possess any well-marked genera, although several of the smaller groups or sub-genera are confined to it. Helicidæ of the generaNanina,BuliminusandAchatinaare abundant and characteristic.
Islands of the West African Sub-region.—The islands in the Gulf of Guinea are, Fernando Po, very near the main land, with Prince's Island and St. Thomas, considerably further away to the south-west. Fernando Po was once thought to be a remarkable instance of an island possessing a very peculiar fauna, although close to the main land and not divided from it by a deep sea. This, however, was due to our having obtained considerable collections from Fernando Po, while the opposite coast was almost unknown. One after another the species supposed to be peculiar have been found on the continent, till it becomes probable, that, as in the case of other islands similarly situated, it contains no peculiar species whatever. The presence of numerous mammalia, among which are baboons, lemurs,Hyrax, andAnomalurus, shows that this island has probably once been united to the continent.
Prince's Island, situated about 100 miles from the coast, has no mammals, but between 30 and 40 species of birds. Of these 7 are peculiar species, viz.,Zosterops ficedulina,Cuphopterus dohrni(a peculiar genus of Sylviidæ),Symplectes princeps,Crithagra rufilata,Columba chlorophæa,Peristera principalis, andStrix thomensis.
In the Island of St. Thomas, situated on the equator about 150 miles from the coast, there are 6 peculiar species out of 30 known birds, viz.,Scops leucopsis,Zosterops lugubris,Turdus olivaceofuscus,Oriolus crassirostris,Symplectes sancti-thomæandAplopelia simplex; alsoStrix thomensisin common with Prince's Island. The remainder are all found on the adjacent coasts. It is remarkable that in Prince's Island there are no birds of prey, any that appear being driven off by the parrots (Psittacus erithacus) that abound there; whereas in St. Thomas and Fernando Po they are plentiful.
III. South-African Sub-region.
This is the most peculiar and interesting part of Africa, but owing to the absence of existing barriers its limits cannot be well defined. The typical portion of it hardly contains more than the narrow strip of territory limited by the mountain range which forms the boundary of the Cape Colony and Natal, while in a wider sense it may be extended to include Mozambique. It may perhaps be best characterised as bounded by the Kalahari desert and the Limpopo river. It is in the more limited district of the extreme south, that the wonderful Cape flora alone exists. Here are more genera and species, and more peculiar types of plants congregated together, than in any other part of the globe of equal extent. There are indications of a somewhat similar richness and specialization in the zoology of this country; but animals are so much less closely dependent on soil and climate, that much of the original peculiarity has been obliterated, by long continued interchange of species with so vast an area asthat of Africa south of the equator. The extreme peculiarity and isolation of the flora must not, however, be lost sight of, if we would correctly interpret the phenomena afforded by the distribution of animal life on the African continent.
Mammalia.—A much larger number of peculiar forms of mammals are found here than in any of the other sub-regions, although it is far less in extent than either of the three divisions of the continent. Among Insectivora we have the Chrysochloridæ, or golden moles, consisting of two genera confined to South Africa; while the Macroscelididæ, or elephant shrews, are also characteristically South African, although ranging as far as Mozambique and the Zambezi, with one outlying species in North Africa. The Viverridæ are represented by three peculiar genera,Ariela,Cynictis, andSuricata. The Carnivora present some remarkable forms:Proteles, forming a distinct family allied to the hyænas and weasels; and two curious forms of Canidæ—Megalotis(the long-eared fox) andLycaon(the hyæna-dog), the latter found also in parts of East Africa.Hydrogaleis a peculiar form of Mustelidæ;Peleaone of the antelopes;Dendromys,Malacothrix, andMystromysare peculiar genera of the mouse family (Muridæ);Bathyergesone of the mole-rats (Spalacidæ);Pedetes, the Cape-hare, a remarkable form of jerboa; andPetromys, one of the spiny-rats (Echimyidæ). The remarkableOrycteropus, or earth-pig, has one species in South and one in North East Africa. We have thus eighteen genera of mammalia almost or quite peculiar to South Africa.
Birds.—These do not present so many peculiar forms, yet some are very remarkable.Chætopsis an isolated genus of thrushes (Turdidæ).Lioptilus, one of the fruit-thrushes (Pycnonotidæ).Pogonocichla, one of the fly-catchers;Urolestes, a shrike;Promerops, a sun-bird;PhiletærusandChera, weaver-birds; and three peculiar genera of larks—Spizocorys,Heterocorys, andTephrocorys, complete the list of peculiar types of Passeres. A wood-pecker,Geocolaptes, is nearly allied to a South American genus. The Cape-dove,Œna, is confined to South and East Africa and Madagascar; andThalassornisis a peculiar form of duck. Several genera are also confined to West and SouthAfrica;—asPhyllastrephus(Pycnonotidæ),Smithornis(Muscicapidæ),Corvinella(Laniidæ);BarbatulaandXylobucco(Megalæmidæ);Ceuthmochares, also in Madagascar, (Cuculidæ);Typanistria(Columbidæ). Other remarkable forms, though widely spread over Africa, appear to have their metropolis here, asColiusandIndicator. Others seem to be confined to South Africa and Abyssinia, as the curiousBuphaga(Sturnidæ); andApaloderma(Trogonidæ).Machærhamphus(Falconidæ) is found only in South-West Africa, Madagascar, and the Malay Peninsula.
Reptiles.—There are 4 peculiar genera of snakes,—Typhline, belonging to the blind burrowing snakes, Typhlopidæ;Lamprophis(Lycodontidæ);CyrtophisandPæcilophis(Elapidæ), a family which is chiefly Oriental and Australian. Of Lizards there are 10 peculiar genera;Monotrophis(Lepidosternidæ), but with an allied form in Angola;Cordylus,Pseudocordylus,Platysaurus,Cordylosaurus,Pleurostichus, andSaurophis, all peculiar genera of Zonuridæ;Chamæsaura, forming the peculiar family Chamæsauridæ;ColopusandRhopitropus(Geckotidæ).
Amphibia.—Of Amphibia there are 4 peculiar genera:Schismaderma(Bufonidæ);Brachymerus(Engystomidæ);PhrynobatrachusandStenorhynchus(Ranidæ). These last are allied to Oriental genera, and the only other Engystomidæ are Oriental and Neotropical.
Fresh-water Fish.—Of fresh-water fishes there is 1 genus—Abrostomus—belonging to the carp family, peculiar to South Africa.
Insects.—South Africa is excessively rich in insects, and the number of peculiar types surpasses that of any other part of the region. We can only here summarize the results.
Lepidoptera.—Of butterflies there are 7 peculiar genera; 2 belonging to the Satyridæ, 1 to Acræidæ, 3 to Lycænidæ, and 1 to Hesperidæ.Zeritis(Lycænidæ) is also characteristic of this sub-region, although 1 species occurs in West Africa.
Coleoptera.—These are very remarkable. In the family of Cicindelidæ, or tiger-beetles, we have the extraordinaryManticoraandPlatychile, forming a sub-family, whose nearest allies are in North America; as well asOphryoderaandDromica, the latter an extensive genus, which ranges as far north as Mozambiqueand Lake Ngami. Another genus of this family,Jansenia, is common to South Africa and South India.
In the large family of Carabidæ, or ground-beetles, there are 17 peculiar South African genera, the most important beingCrepidogaster,Hytrichopus,Arsinoë, andPiezia. Three others—Eunostus,Glyphodactyla, andMegalonychus—are common to South Africa and Madagascar only. There is also a genus in common with Java, and one with Australia.
Of Lucanidæ, or stag-beetles, there are 3 peculiar genera; of Cetoniidæ, or rose-chafers, 14; and of Buprestidæ, 2.
In the great family of Longicorns there are no less than 67 peculiar genera—an immense number when we consider that the generally open character of the country, is such as is not usually well suited to this group of insects. They consist of 5 peculiar genera of Prionidæ, 25 of Cerambycidæ, and 37 of Lamiidæ.
Summary of South-African Zoology.—Summarizing these results, we find that South Africa possesses 18 peculiar genera of Mammalia, 12 of Birds, 18 of Reptiles, 1 of Fishes, 7 of Butterflies, and 107 of the six typical families of Coleoptera. Besides this large amount of speciality it contains many other groups, which extend either to West Africa, to Abyssinia, or to Madagascar only, a number of which are no doubt to be referred as originating here. We also find many cases of direct affinity with the Oriental region, and especially with the Malay districts, and others with Australia; and there are also less marked indications of a relation to America.
Atlantic Islands of the Ethiopian Region.St. Helena.—The position of St. Helena, about 1,000 miles west of Africa and 16° south of the equator, renders it difficult to place it in either of the sub-regions; and its scanty fauna has a general rather than any special resemblance to that of Africa. The entire destruction of its luxuriant native forests by the introduction of goats which killed all the young trees (a destruction which was nearly completed two centuries ago) must have led to the extermination of most of the indigenous birds and insects. At present there is no land bird that is believed to be really indigenous, and but onewader, a small plover (Ægialitis sanctæ-helenæ) which is peculiar to the island, but closely allied to African species. Numerous imported birds, such as canaries, Java sparrows, some African finches, guinea-fowls, and partridges, are now wild. There are no native butterflies, but a few introduced species of almost world-wide range. The only important remnant of the original fauna consists of beetles and land shells. The beetles are the more numerous and have been critically examined and described by Mr. T. V. Wollaston, whose researches in the other Atlantic islands are so well known.
Coleoptera of St. Helena.—Omitting those beetles which get introduced everywhere through man's agency, there are 59 species of Coleoptera known from St. Helena; and even of these there are a few widely distributed species that may have been introduced by man. It will be well, therefore, to confine ourselves almost wholly to the species peculiar to the island, and, therefore, almost certainly forming part of the endemic or original fauna. Of these we find that 10 belong to genera which have a very wide range, and thus afford no indication of geographical affinity; 2 belong to genera which are characteristic of the Palæarctic fauna (Bembidium,Longitarsus); 3 to African genera (Adoretus,Sciobius,Aspidomorpha); and two species ofCalosomaare most allied to African species. There are also 4 African species, which may be indigenous in St. Helena. The peculiar genera, 7 in number, are, however, the most interesting. We have firstHaplothorax, a large beetle allied toCarabusandCalosoma, though of a peculiar type. This may be held to indicate a remote Palæarctic affinity.Melissius, one of the Dynastidæ, is allied to South African forms.Microxylobius, one of the Cossonides (a sub-family of Curculionidæ) is the most important genus, comprising as it does 13 species. It is, according to Mr. Wollaston, an altogether peculiar type, most allied toPentarthrum, a genus found in St. Helena, Ascension, and the south of England, and itself very isolated.Nesiotes, another genus of Curculionidæ, belongs to a small group, the allied genera forming which inhabit Europe, Madeira, and Australia. A third peculiar and isolated genus isTrachyphlæosoma. The Anthribidæ are represented by2 genera,NotioxenusandHomœodera, which are altogether peculiar and isolated, and contain 9 species. Thus no less than 27 species, or more than half of the undoubtedly indigenous beetles, belong to 5 peculiar and very remarkable genera of Rhyncophora.
It appears from this enumeration, that the peculiar species as a whole, exhibit most affinity to the Ethiopian fauna; next to the South European fauna; and lastly to that of the islands of the North Atlantic; while there is such a large amount of peculiarity in the most characteristic forms, that no special geographical affinity can be pointed out.
Land Shells.—These consist of about a dozen living species, and about as many extinct found in the surface soil, and probably exterminated by the destruction of the forests. The genera areSuccinea,Zonites,Helix,Bulimus,Pupa, andAchatina. TheBulimi(all now extinct but one) comprise one large, and several small species, of a peculiar type, most resembling forms now inhabiting South America and the islands of the Pacific.Zonitesis chiefly South European, but the other genera are of wide range, and none are peculiar to the island.
The marine shells are mostly Mediterranean, or West Indian species, with some found in the Indian Ocean; only 4 or 5 species being peculiar to the island.
Tristan d'Acunha.—This small island is situated nearly midway between the Cape of Good Hope and the mouth of the La Plata, but it is rather nearer Africa than America, and a little nearer still to St. Helena. An island so truly oceanic and of whose productions so little is known, cannot be placed in any region, and is only noticed here because it comes naturally after St. Helena. It is known to possess three peculiar land birds. One is a thrush (Nesocichla eremita) whose exact affinities are not determined; the other a small water-hen (Gallinula nesiotis) allied to our native species, but with shorter and softer wings, which the bird does not use for flight. A finch of the genusCrithagrashows African affinities; while another recently described asNesospiza acunhæ(Journ. für Orn. 1873, p. 154) forms a new genus said to resemble more nearly some American forms.