THE CHARACTERS FURNISHED BY THE TEETH. 659 



almost disappeared ; the inferior incisive arcade is narrow and but 

 slightly convex ; an interspace now forms between these teeth. The 

 tongue overhangs the bars more, and the saliva runs from the mouth 

 when the jaws are separated. Viewed in profile, the latter form an 

 ogive more or less acute. The obliquity of the corners is more marked 

 than that of the intermediates. Viewed in front, the teeth of each 

 arcade are very convergent by their crown. (Plate XXVIII.) 



Eighteen Years. — The dental tables become elongated from 

 before to behind. The central enamel of the superior pincers is absent. 



Nineteen Years. — The tables of the pincers and the intermediates 

 are longer from before to behind than transversely, — biangidar ; besides, 

 these tables, by their lateral borders, converge behind and diverge in 

 front. Central enamel absent in the superior intermediates. Viewing 

 the jaws in front, the convergence of the corners is very decided. The 

 teeth are more horizontal, often too long. (Plate XXIX.) 



Twenty-one Years. — In profile, the two arcades meet each other 

 at a very acute incidence. The superior teeth are convergent in front, 

 and conceal the greater part of the inferior. The inferior incisive 

 arcade is, so to speak, no longer convex, and the teeth here become more 

 separated from each other ; their tables are becoming flattened from side 

 to side ; finally, their posterior border is covered by a layer of enamel 

 which gradually becomes thinner. A layer of radical cement often 

 surrounds the base of the teeth. (Plate XXX.) 



Thirty Years. — Beyond twenty years of age the horse is con- 

 sidered as havine; reached the limit of his life. The characters of the 

 mouth are then those of extreme old age. Sometimes the teeth are too 

 long and too horizontal ; at other times, on the contrary, they are alto- 

 gether too short and worn doivn to a level tvith the gums. In all cases, 

 only a small portion of the root remains in the alveolar cavity. 

 When the lips are separated, the maxillary bones, at the level of the 

 palatine arch and the symphysis of the inferior jawbone, are very thin. 

 Viewed in profile, the dental arcades scarcely show more than the cor- 

 ners and the intermediates ; the pincers remain hidden by the latter. 

 Viewed in front, the teeth are so straight and prominent that, in 

 order to see the inferior incisors, the head must be raised. The superior 

 converge towards the median line by their free extremity, whilst they 

 are very divergent at their base ; wide triangular interspaces, into 

 which pointed prolongations of the mucous membrane as well as brown- 

 ish alimentary matter are prolonged, separate the pincers from the 

 intermediates and the latter from the corners. 



The tables of friction become more and more flattened upon their 



