TEETH IN HERBIVORA. 53 



In order to consider this subject more fully, we may com- 

 mence with the 



TEETH IN HERBIVORA. The incisor teeth vary in impor- 

 tance in our grass-feeding animals, and are absent in the 

 upper jaw of the ruminant, where their place is occupied 

 by the fibre-elastic pad referred to at page 13. In the 

 horse there are two pairs of tushes, and we observe twelve 

 large molars in the upper and lower jaw. In front of the 

 molars there are occasionally small rudimentary teeth, called 

 by horsemen wolves' teeth, and various superstitions are 

 connected with these accidental and harmless elements of 

 the dental apparatus. The molar teeth of the horse have 

 the grooves produced by the cement arranged longitudinally 

 to favour mastication. (See Fig. 23.) 



TO DETERMINE THE AGE OF THE HORSE BY THE TEETH. 



It is chiefly by the incisor teeth that we can tell how old a 

 horse is, and it is important to consider the change in shape 

 and general appearance which these teeth undergo. There 

 are temporary and permanent incisors. The first have a 

 broad crown, flattened somewhat from before back, with a 

 wearing surface far wider from side to side than from behind 

 forwards. They have a distinct neck, and a narrow sharp 

 fang. The appearance of the temporary teeth is shelly, and 

 there is a well-marked depression or infundibulum on the 

 upper aspect. The front of the tooth is of a pearly white, 

 and grooved or fluted. (See Figs. 10, 14.) The permanent 

 incisor is much larger than the temporary. Its crown thicker, 

 of a duller colour, and the cavity or infundibulum is deeper. 

 (See Figs. 17, 18.) The neck of the tooth is not so well 

 defined, and as the animal acquires age, we find a very re- 

 markable change in the shape. This is best seen at Fig. 19, 

 which represents different sections of the permanent incisor 

 as its surface appears from progressive wear. 



