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Show 1902.] OF HORNS AND ANTLERS. 219 II b. Terminal, further development of type II a. Epichon-drotic growths proliferating freely and with broad bases, so that they form intraperiosteal growths, separated from the cranial bones, and consequently ossifying independently of them, ultimately fusing with them. Cranial apophyses or exostoses, or pedicles, much reduced in height. Disuse of the outgrowths, implying cessation of the irritation upon the basal periost (i. e. between the growth and the cranial bone), explains diminution of the pedicles and their late fusion and the long delayed process of ossification. But the development of the ecchondrotic mass, inherited from the ancestral stock, and subsequent ossification still go on, although without a purpose, and they produce organs which, owing to their late fusion with the cranium, their original home, now appear as osteoderms, although in reality they are pseudo-primitive organs. The integument remains hairy, except on the top where the epiderm proliferates and comities a little. Example, the Giraffe. (Text-fig. 25, II b.) II c. Apparent loss of all these armaments, the last remnants being frontal bosses: Okapi. (Text-fig. 25, lie, p. 216.) It is worth noting that, while the females of Sivatherium and Samotherium are, by general consent, not credited with " antlers," the Giraffe makes an exception in this respect. This fits in with the view, expressed in this paper, that Giraffes represent a terminus of one line of development. There are some typical Cervince of which both sexes are antlered. The acquisition of secondary sexual organs by the females is mainly a question of time. It is an illustration of simple, direct inheritance from the other sex, so common in organs which are connected with sexual activity, e. g. clitoris, mamma?, spurs. These things are of not the slightest good to their new possessors, but they do no harm either. They are therefore neglected, rather not discovered, by natural selection. Ill, The same initial stage as type II. A long pedicle with a simple broach, covered with hairy skin, but the epidermal portion of this tegumentary sheath proliferates, glues the hairs together and embeds them. The horny sheath is an efficient protection against injury; the external or cutaneous and the internal vascular supply remain, and the simple antler is shed no longer. Immature specimens still show a thickened, burr-like swelling at the juncture of the pedicle and antler. W e assume that the horn-sheath consisted originally of an imperfectly welded material still liable to fraying, until it became effective enough to prevent any necrosis and subsequent shedding of the antler, which thereby becomes an os cornu. So long as the hair preponderates in the deeper strata, the shedding and |