f 



HEAD AND NECK OF THE HORSE 



87 



other cheek-teeth of the horse. When less well developed, the crown 

 is generally a small and simple cone. . At its best the mandibular 

 tooth is small and possessed of a simple conical crown. 



In the permanent dentition the incisor teeth have crowns that are 

 compressed in such a manner as to produce a labial and a lingual surface, 

 and the chewing surfaces are oval or ovoid. ^ The crown of the first incisor 

 is the longest and broadest, while that of the third tooth is the shortest 

 and smalles^ In none of them is* there any constriction indicating the 



Infundibulum. *^ 



Cement, t. 



Enamel 



Tooth cavity 



Fig. 31. — Diagram of longitudinal section of an incisor tooth. 



position of the neck. The roots of all the incisors are long and curved, 

 and so implanted in the bone that they are directed towards a common 

 point. The root of the first tooth is somewhat longer than that of the 

 second, while that of the third is the shortest. The curvature of the 

 root is, more marked in the maxillary than in the mandibular teeth. 



1 The description here given of the crowns of the various teeth is intended to 

 apply to the exposed parts in young adult animals. If the term "crown" is held 

 to include all that part of a tooth on which enamel is present, the teeth of the young 

 adult must be described as having a considerable amount of their crowns buried 

 beneath the gum ; f9r sections show that folds of enamel are carried very deeply into 

 the interior of the tooth, with a corresponding prolongation of the surface enamel 

 down into the tooth-socket. That is, in the young tooth there is an exposed crown, 

 visible above the gum, and an embedded part of the crown to which it is customary 

 to apply loosely the name root ; though the root, in the strict application of the 

 term, is the comparatively short, enamel-free, deepest part of the tooth. As the 

 tooth wears awa,y the embedded part of the crown is gradually exposed. 



