TEETH OF THE HOESE. 



271 



impressed by two deep longitudinal channels. In tlie lower 

 jaw the teeth are narrower transversely than in the upper 

 jaw, and are divided externally into two convex lobes, by 

 a median longitudinal fissure; internally they present 

 three principal unequal convex ridges, and an anterior 

 and posterior narrower ridge. All the valleys, fissures, 



Fig. 72. 



GRINDING SURFACES OF THE UPPER AND LOWER MOLARS OF A HORSE. 



and folds in both upper and lower grinders are lined by 

 enamel, which also coats the whole exterior surface of the 

 crown. Of the series of six teeth in each jaw, the first 

 three, p 2, 3, 4, are premolars, the rest, m 1, 2, 3, are true 

 molars. 



The canines are small in the horse, and are rudimental 

 in the mare ; the unworn crown is remarkable for the 

 folding in of the anterior and posterior margins of enamel. 

 The upper ca:nine is situated in the middle of the long- 

 interspace between the incisors and molars; the lower 

 canine is close to the outer incisor, but is distinguished by 

 its more pointed form. The incisors are six in number 

 in both jaws ; they are arranged close togeiher in a curve. 



