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Show 1902.] OF H O R N S A N D ANTLERS. 209 integument of the Giraffe is only hairy, that of the Prongbuck is hairy and horny, that of the Bovidae only horny. Having satisfied himself about the apophysial nature of the antlers in opposition to the epiphysial condition of the bony core of the Giraffe and Bovidae, he naturally feels justified about the complete removal of the Giraffe from the Cervidae and the fundamental difference between bovine and cervine ruminants. These conclusions are not satisfactory. First, it is not likely that several fundamentally different kinds of armaments should have been developed within such a circumscribed and specialized group as the higher Ruminants or Pecora. It is of greater scientific value if we can trace all these armaments not only to the same beginning, but bring them all into one evolutionary line, so that these organs afford a clue to the phyletic development of the various groups of Ruminants. The ultimate cause of these armaments must have been the same, namely butting with the head, causing irritation, which in turn leads to hypertrophy of the cranial bones, together with the covering periost, cutis, and epidermis\ Secondly, the origin of the os cornu, sometimes with a separate centre of ossification, has to be accounted for, since it is quite impermissible to assume that it was a preformed bone in the skin, which has later become fused onto the skull. Nor is there a single instance in mammalian pathology of loose ossification in the cutis due to repeated pressure or irritation, conditions which, on the contrary and invariably, lead to exostosis of the underlying already existing bone. Thirdly, there is the palaeontological evidence, not very plentiful, but one fossil in hand is worth more as a proof of phyletic speculation than ever so many ontogenetic observations. Curiously enough, few palaeontologists, whilst throwing much light upon the evolution of the cervine antlers, have tried to take a broad view of the phyletic side of the whole question, and the comparative anatomists have, as usual, left the fossils severely alone. Lastly, there is the Giraffe and its relation, the Okapi, the former with multiple, early appearing protuberances in both sexes, the other apparently with none. The question at issue requires a renewed investigation of the development of the cervine and bovine armaments and a sifting of the palaeontological evidence. I. Development of the Cervine Antlers. The first growth of a buck's antler in his first year is already a compound structure. It begins with a bulged out elevation or knob 1 The o-eneral considerations and conditions have been well described and argued out by J J. Cunningham, ' Sexual Dimorphism,' pp. 73-104. The evolution of horns and antlers, studied with due regard to the interesting physiological features, is one of the clearest demonstrations of the acquisition and inheritance of new organs, whilst any attempt to account for them (not their shape!) by variation and selection alone would be ridiculous. |