the forehead, and a pair somewhat farther back. The paired horns, at any rate, are present in both sexes, although much smaller in the females than in the males. From their narrow ears giraffes are evidently adapted to live in open country, or, at all events, in such covert as leaves their heads and necks exposed. On the other hand, the great spreading ears of the okapi proclaim with equal clearness that their owner is a forest animal.* So far as can be ascertained, the male okapi is always provided with a single pair of horns, of some five or six inches in length (fig. 2), while the female is generally hornless, although, as in the case of the American

FIG. 2, SKULL OF MALE OKAPI.

(After C. I. Forsyth-Major.)

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prongbuck, small horns may occasionally be developed in that sex. Sir Harry Johnston is commonly credited with being the discoverer of the okapi, and he was certainly the first to make the entire creature known to European science. It appears probable, however, that a piece of striped skin obtained some twenty years earlier by the German explorer, Dr Junker, and supposed at the time to belong to the zebra-antelope, really pertained to a young okapi, and was thus the first evidence of that animal brought to Europe.

The absurd idea that the okapi is a hybrid between a giraffe and a zebra still appears to be current. Apart from the fact that hybrids between such widely different animals do not occur in nature, the okapi is essentially a giraffe in structure, and fully a dozen specimens are known.

Both giraffes and okapis are characterised by the peculiar roughness of the enamel of their teeth, the structure of which recalls the skin of the large black slug. They are further distinguished by the circumstance that the outermost of the four lower pairs of front teeth -corresponding to the canines of other mammals-have divided or lobate crowns, probably for the purpose of assisting in the combing process in which these animals strip the leaves from a bough.

As regards the past history of the group, it may be noted that remains of extinct giraffes occur in the Pliocene deposits of Greece, Persia, northern India and China, so that these animals were widely distributed during the Pliocene division of Tertiary time in Asia. Moreover, some of these extinct forms seem to have had shorter limbs than their modern relatives, thus pointing to their being generalised ancestral types. Okapi-like ruminants (Tragoceros or Samotherium) are also known from the Pliocene beds of Greece, Samos, China, etc., in which, as in their existing representative, the males were horned and the females hornless. Nor is this all; for there was also a large number of allied ruminants of gigantic proportions, such as Sivatherium and Helladotherium, distributed over southern Europe, Asia, and North Africa. But, if we except one doubtful tooth from a superficial formation, not a vestige of any one of these creatures has hitherto been detected in a fossil state in Ethiopian Africa or Egypt.

Giraffes and okapis form but a small group; and by far the most numerous of the existing ruminants of Africa south of the Sahara are the various kinds of antelopes, all of which, with the exception of the true gazelles, belong to groups or genera now unknown beyond the limits of the Ethiopian region, save for a few inhabiting the northern part of the continent, Syria, etc. Among the larger forms may first be mentioned the hartebeests and their relatives the blesbok and bontebok. Remains of some members of this group have been found in the superficial or Pleistocene beds of Egypt, but not in lower strata; extinct forms occur, however, in the Indian Pliocene. Of the paleontological history of their near relatives the gnus, nothing whatever is known. Passing by numerous smaller forms,

such as the dik-diks, oribis, klipspringers, duikers, etc., of which the past history is likewise a blank, we come to the waterbucks and their smaller relatives the kobs, all of which are exclusively confined to Ethiopian Africa. Here, however, we are confronted with the noteworthy fact that remains of apparently generically identical antelopes occur in the Siwalik Hills of northern India. The sable and roan antelopes, together with their near relatives the addax and the various kinds of oryx, form another characteristic group of Ethiopian antelopes, some of which range, however, into northern Africa and Syria. The roan antelope occurs in fossil form in the superficial deposits of Egypt, while an extinct member of the same group has been recorded from the Pliocene Siwaliks of India. Moreover, an extinct generic type of oryx is met with in the equivalent deposits of Greece. More significant still is the occurrence of remains referred to an addax in the superficial deposits of China; such remains, in common with those of numerous other mammals, having been obtained in the druggists' shops at Shanghai, where they are sold as medicines.

Among the largest and handsomest of all African antelopes are the lordly elands, the brilliantly coloured bongo of the equatorial forest tract, the graceful and more widely distributed kudus, and the equally elegant but more numerously represented bushbucks, inclusive of the water-loving situtunga. All these are strictly

Ethiopian forms; but it is noteworthy that they have a near, although less specialised, relative in the Indian nilgai. When we enquire into the past history of this group we find that extinct nilgais occur in India and China, where various types of kudu, eland, and, perhaps, bushbucks, are likewise met with; while elands are found in a fossil state in the Pliocene of Greece, and not improbably also in that of India. The full significance of these facts will be noticed later.

Of the little water-chevrotain of West Africa, which represents a genus by itself, with extinct forms in the Pliocene of Europe, it must suffice to mention that its nearest living allies are the true chevrotains or mousedeer of south-eastern Asia, which also date from the Pliocene epoch, and have nothing to do with true deer.

Although the common hippopotamus and its pigmy

relative of Liberia are now both confined to Ethiopian Africa, the former was once widely distributed over Europe, while in the superficial deposits of the Mediterranean islands there occur quantities of remains of species more or less closely related to the latter. The earliest known representatives of the group are found, however, in the Pliocene of northern India and Burma; and, as these belong to generalised and ancestral types, while no such fossils are at present known from Ethiopian Africa, the presumption is that the group is of northern

origin. As to the pigs, it must suffice to say, in the first place, that the hideous wart-hogs (fig. 3), now exclusively Ethiopian, appear to exhibit some signs of relationship with certain Indian fossil swine. And, secondly, that the bush-pigs (bosch-varks)-an equally characteristic Ethiopian and Malagasy group-are almost undoubtedly akin to certain extinct pigs from the Pliocene of Europe and Asia.

Highly characteristic of Ethiopian Africa are the various species of zebra and quagga, as well as the typical wild asses. Unfortunately, paleontology is silent as to their past history, not from the lack of fossil remains of

Equidæ, but for the reason that, with the exception of the true horse (which is readily distinguished by the great breadth of the fore hoof-bones), the teeth and bones of most of the existing members of the horse tribe are so alike that, save in the matter of size, it is almost, if not quite, impossible to distinguish one species or, at all events, one group from another in the fossil state. Nevertheless it is quite probable that some of the extinct Asiatic Equida were really zebras.

More satisfactory is the evidence afforded by the rhinoceroses. Africa, south of the Sahara, is now the home of two species of these monsters, namely, the white, or Burchell's, rhinoceros, formerly abundant in Cape Colony and the adjacent districts, and still surviving in an isolated tract on the equator in the neighbourhood of Lado, and the much more widely spread black or common rhinoceros. These species agree in possessing two horns, as well as in the absence of folds in the skin, and in the lack of front teeth when adult. In the two latter respects they differ markedly from the living Asiatic rhinoceroses, one of which is two-horned, while the two others have only single horns. A fossil rhinoceros closely akin to the black species has, however, left its remains in the Pliocene Tertiary of Greece; while some of the extinct species from the Asiatic and European Pliocene and Pleistocene deposits are also more or less nearly akin. On the other hand, the great extinct woolly rhinoceros of Europe, Siberia, and North China, whose frozen carcases, like those of one of the other species, are occasionally met with in the 'cold storage' of the Siberian tundras, appears to have been very closely related to the white species. No traces of rhinoceros-like creatures have hitherto been detected in the early Tertiary deposits of Egypt, although such are common in the equivalent formations of Europe and North America.

A decidedly different story is told by the hyraces, which, as already said, form a distinct sub-order of ungulates, and are chiefly Ethiopian, although one species ranges into Syria. All the existing species are small creatures, comparable in size to a rabbit, some being terrestrial and others arboreal. Many of the fossil forms indicate, however, comparatively large animals, of the