1901.] I I\ I. IfoUMii QIRABEB 1 UOM MOUNT ELGON 483 



therefore that it would lie natural to homologize with the mizen 

 horus of the modern Giraffe. 



I would therefore submit that possibly the large antler-like 

 posterior horns of Sivatherium^ and more certainly the thick 

 divergent ones of Bramaiherium and the mizen horns of QirajFa, 

 and perhaps certain low projections in Samotherium and OJcapia, 

 are all different phases of out- and the same development. No 

 doubt, strictly speaking, one cannot say that the low projections 

 of the last three are homologous with the actual horns of the first 

 two, for, so far as we yet know, they are without that os cornu 

 which may be presumed to have been present in the fossil, and 

 would have been the true homologue. But just as the rounded 

 swelling on the nose of a female Giraffe may be said to correspond 

 to the fore horn of the male, so these low projections may equally 

 be held to represent the true horns of the allied animals. 



The last question to be considered is as to whether, if these 

 homologies be admitted, we should look upon the mizen horns of 

 the Giraffe as representing an early stage in the development 

 of larger horns, or as the degenerate descendants of horns which 

 have been of full size in the Giraffe's ancestors. 



I myself believe that the latter is the true explanation, and 

 that in these horns we have the degenerate descendants of larger 

 ones, not necessarily as large or highly specialized as those of 

 Sivatherium, but still of great use at the time when the Giraffe's 

 ancestors, like Deer and Antelopes, used their horns and not their 

 hoofs as their primary means of defence. AVith the lengthening 

 of the legs and the utilization of the hoofs as weapons ', the 

 functional importance of the horns would naturally diminish, a 

 suggestion which would account for the degeneration in Giraffa 

 of organs which in all other groups appear to have continuously 

 increased in size and complexity as time has gone on. It must be 

 admitted that this easy explanation will not give us a clue to 

 the history of the Okapi, but, so far as we know, that animal 

 is unusually free from enemies against which it would have to 

 defend itself, BO thai al the present time it would appear to have 

 no need for functional horns. Whether its hornless a condition is 

 a remnant of an early stage of evolution, or is an evidence of 

 degeneration, opinions are much divided, and owing to the 

 difficulty or impossibility of satisfactorily proving the correctness 

 of either view, the expressing of an opinion is rather a fruitless 

 amusement. Bui if 1 were to venture on an opinion, it would be 

 rather on the side of the degeneral ion i beorj , although I necessarily 

 take this vie* with the great esl hesitation, owing to the absence 

 of any real evidence bearing one way or the other. 



main horns, which while possibly, indeed probably, due merely to distortion, 

 ,-i,t the tore horns of Giraffa. It this is the ease, it 

 would effectually dispose of the suggestion thai the Long horns of Samotheriwm 

 ■ horns of the Q iraffe, 

 1 cf. Bryden, t. c. p. 500; and de Winton, P. Z. 8. L897, p. 283, 

 ■ Elorni may yet be found to < ur in the old male. 



