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Show 214 DR. H. G A D O W O N T H E EVOLUTION [Mar. 18, on the bone-core. Forbes remarked that in his specimen " the prong is not yet visible, but may be felt at the base of the pedicel, close to the skull, on the anterior margin of the horn." (Cf. text-fig. 25, III2.) In well-macerated specimens in the Cambridge Museum, the difference between the rather long pedicle and the decidedly short os cornu proper is well marked. Owing to the continued and active growth of the shoe from the base, the axial point and the prong are gradually pushed upwards, so that the prong comes to lie far above the skull in a level even above the base of the os cornu, which in the adult is thinned out into a non-osseous, tapering, string-like cone of soft connective-tissue and periost. The shoe continues to grow basally, and ultimately engulfs not only the os cornu but also nearly the whole pedicle. IV. The Giraffe and the Okapi. It is of no importance to the present investigation whether the few hitherto known skulls of the Okapi are those of young or adult males or females. The skulls exhibit the same tendency towards broad-based swellings on the fronto-parietal and facial regions as in the Giraffe. Even in the latter genus these parts, although slight and bulging, owing to the pneumatic condition of the bones of such a weakly constructed skull, can ill be reconciled with the only reasonable explanation of the genesis of horns and antlers. W e have to assume that the ancestors of the Giraffe had stronger skulls, with serviceable antlers, and that these armaments have caused the bosses of the supporting bones, and that in the Giraffe these very armaments have degenerated into now merely ornamental remnants, vanished in the Okapi. It is possible, as M r Thomas has sagaciously suggested, that the degeneration of these armaments is correlated with the lengthening of the fore-limbs and neck, the animals ceasing to fight with their heads and using the powerful fore-limbs instead. This applies obviously to the Giraffe, but not so easily to the Okapi, unless we look upon the latter as the most degraded descendant of the whole group, which, although perhaps never numerous, was certainly more widely distributed in the shape of several genera and species. At any rate, the Okapi represents not the beginning, but the most modern and most modest member of a tribe which has flourished in bygone times. There are other proofs that the Giraffe's armaments represent no primitive condition. The bony growths appear loosely in the skin, a condition which finds a parallel in the cases of separate ossification of the os cornu of certain Bovinm. Their matrix has become so emancipated from the skull, that they shift their position before fusing onto the cranium, and their mode of fusion is most peculiar. As Mr. Thomas has expressed it graphically, not only at the base of the growth, but around it, and quite irregularly, there appear little bony nodules, which become amalgamated with the cranium as if wax had been dropped upon it. Such numerous, small and irregularly scattered " osteoderms " |