456 THE MKCHANICAL FUNCTIONS. 



on the same principles as those which regnhite the 

 growth of turbinated shells. The horns of the Ox 

 and of the Antelope tribes are formed of longer and 

 more continuous fibres, which are closely com- 

 pacted together, and exhibit very distinctly the 

 series of hollow cones of which they are composed. 

 The horns of the RhinoceroSy both of the one 

 and the two horned species, grow from the integu- 

 ment covering the nose, to which they adhere 

 without having any connexion with the subjacent 

 bones. They have a pyramidal shape, and are 

 composed of parallel fibres, resembling hairs, 

 agglutinated together into a solid mass by a ma- 

 terial which acts as a cement. This fibrous struc- 

 ture is most distinctly seen at the base of the horn, 

 where the ends of the fibres project, like those of 

 a brush, from the surface. When these horns are 

 sawn transversely, and examined with a magnify- 

 ing glass, a great number of orifices are seen, 

 marking the empty spaces that intervene between 

 the hairs ; and if the section be made in a longitu- 

 dinal direction, the same spaces give rise to the 

 appearance of parallel grooves. These horns are 

 not deciduous, like those of the stag: but continue 

 to adhere to the skin, and to grow from the root, in 

 proportion as they are worn at the extremity. 



§ 6. Solipeda. 



The Solipeda form a natural family of quadrupeds, 

 including the Horse, the Ass, the Qungga, the 

 Zebra, &c. which are very nearly allied in their 

 conformation to the ruminant tribe. To combine 



