THE HEAD AND NECK. 143 



nation of the same smooth mucous membrane which 

 lines the passage. In veterinary anatomy it is called 

 the " false nostril." 



If this were all we knew about this organ it would 

 be unsatisfactory enough, but it immediately acquires 

 interest when we learn that in the tapir a similar 

 structure, only in a very much more developed con- 

 dition, is found. In that animal it runs upwards, as 

 a long, narrow tube, from the external nostril, at 

 first in contact with its fellow of the opposite side, 

 and afterwards, taking a curiously curved course, 

 terminates in a dilated, closed extremity, which lies 

 in a distinct groove by the side of the upper part of 

 the nasal bone. Its walls are cartilaginous, and con- 

 voluted in such a manner as greatly to increase the 

 area of the internal surface. It is obvious that the 

 "false nostril" of the horse cannot be looked upon 

 as anything specially belonging to the economy of 

 that animal, but rather as a rudimentary condition 

 or survival of a structure which is far more highly 

 developed in some of the more primitive forms of 

 Perissodactyles. This view is greatly strengthened 

 by the recent discovery of an exactly similar struct- 

 ure in the rhinoceros, only in a condition interme- 

 diate between that in which it is found in the horse 

 and the tapir * 



* E. F. Beddard, Proceedings of the Zoological Society of 

 Loudon, 1889, p. 10. 



