138 THE HOMOLOGIES OF THE 



From what I have said above it will be gathered that 

 I regard all these horny structures as really homologous 

 with hair, the production of which is one of the essential 

 offices of mammalian skin. Again, I look upon the slowly 

 growing '* core " of the bullock's or antelope's horn as really 

 and structurally corresponding to the enormous outgrowth 

 that periodically adorns the head of most of the stags ; and 

 I consider that the different rate of their growth is quite 

 sufficient to account for the apparent difference of structure 

 of the two forms. The ornamental appendages on the top 

 of the head of the giraffe I do not regard as true horns, 

 as they do not by age gain any annual additions, and are, 

 as stated by Owen, simply skin-covered " epiphyses," seated 

 upon the top of the bead, and are not fitted to be used as 

 weapons of warfare, and in fact are not so used at all. 

 I think, then, that there is reason to consider that the 

 horns of the Bovidse and of the rhinoceros are not so 

 dissimilar from those of the Cervidse in their histological 

 relations as at first sight they appear to be, and that the 

 natural processes in the two cases are not so markedly 

 divergent as we have generally been led to suppose. 



Having now, as I hope, shown the close connection of the 

 horns of the Cervidse with those of the Bovidas, and the 

 connection of the horns of the Bovidse with those of the 

 rhinoceros, the similarity of structure of the single or double 

 horn of the rhinoceros with the baleen plates growing from 

 the upper jaw of the ''Right" whales is w^ell known to 

 microscopists, and the frayed edges of the baleen plates 

 having been shown to be separate hairs, the whalebone-like 

 hairs or bristles of the tail of the elephant, the well-known 

 modification of hair observed in the quills of the porcupine 

 and hedgehog, or the feathers of birds, all furnish strong 

 evidence of the homology of all these horny structures with 



