136 THE HOMOLOGIES OF THE 



height they give off a short branch projecting forwards at 

 an angle of about forty-five degrees. The bony cores, it 

 should be observed, on examination are found to be simple 

 and dagger-shaped, without any branching. Again, the 

 prong-buck is unique among cavicorns in shedding the 

 horn-sheaths annually ; this generally occurs about the 

 month of October, but in young individuals it may be 

 deferred until January. Mr. Caton, who has given the best 

 account of the growth of their horns, says that in looking 

 into the hollow of a shed horn, it will be seen that the 

 interior contains a number of coarse light-coloured hairs, 

 all of which are firmly attached, while in the lower part 

 many pass completely through the horn. The core is also 

 covered with similar hairs, growing from an investing skin, 

 and he concludes that these hairs must be broken through 

 when the horn is shed. He considers, finally, that the 

 horn-sheath " is nothing more than a mass of agglomerated 

 hairs." On examining the head of a prong-buck from 

 which the horns have been recently shed, it will be observed 

 that the summits of the cores are already capped with small 

 new horns which are quite hard at the tips, but lower 

 down are found to become gradually softer and softer, until 

 the skin investing the core is reached. As the young horny 

 material grows downwards, it becomes gradually more solid, 

 until by the time the base is reached the horn has become 

 a completed weapon. This mode of growth reminds one 

 of that of teeth, generally, which commence as thin scales at 

 the top of the tooth pulp, which pulp becomes in time 

 wholly converted into true tooth substance by the in- 

 terstitial deposition of earthy salts and the formation of 

 dentinal tubes. 



The teeth we know are, like horns, developed from the 

 skin in the first place, although afterw^ards they may, in 



