RUMINANT QUADRUPEDS. 



355 



of a hollow cone, occupying the part towards the apex of 

 the former cone, and extending farther towards the base. 

 Hence a longitudinal section of the whole presents the ap- 

 pearance represented in the annexed figures (218*,) where 

 A is the section of the horn of an Ox, and b, a similar sec- 

 tion of the horn of an Antelope. C is a magnified view of 

 the extremity of the latter, together with a portion of the 

 bone D, which occupies the axis of the horn. 



In this process of the formation of horn, as happens in 

 that of shells, there sometimes occur irregularities, or peri- 

 odical intermissions and increase of action in the secreting 

 organs, giving rise to transverse grooves, or ridges. Tliese 

 may be seen in the horns of the goat, in which the fibres 

 are short, and laid one over another with the same regula- 

 rity as the tiles of a house. The tendency in these horns 



to assume a spiral form is explicable on the same principles 

 as those which regulate the growth of turbinated shells. 



