ITS NEAREST EXISTING KKLATIONS 



51 



that the fibres differ from them in growing around a long 

 free papilla on the surface of the derm, instead of from 

 a very short papilla sunk deeply in a follicular involu- 

 tion of the same. These horns are really warts, which 

 have assumed a solid and definite form, and the stages 

 by which they may have developed are illustrated in the 

 irregularly-shaped supplementary horns which are some- 

 times found either on the face or other parts of the body, 

 the product of some local abnormal condition of the 

 skin. 1 



When fully developed, the horns are of a more or less 

 conical form and usually curved backwards at their ends, 

 and often grow to a great length (three or even four 

 feet), but they are constantly worn away at the ends and 

 sides by being rubbed against trees or stones, and are 

 continually growing at the base. Their length and 

 shape are, therefore, subject to considerable variation, 

 even in the same individual at different times, and so 

 cannot be depended upon for the distinction of species, 

 as some naturalists have imagined. Though not 

 normally shed, they are occasionally torn off at the base, 2 

 in which case a new horn will grow in its place, although, 



1 See a case of an African rhinoceros with a third horn described 

 in the Proceedings of th e Zoological Society of London, 1889, p. 418. 



2 This happened in 1870 to the male Indian rhinoceros still living 

 in the gardens of the Zoological Society of London, in an effort to 

 raise with its horn a strong transverse iron bar at the lower part of 

 the railings of the inciosure in which it was confined. 



e 2 



