CHAPTER XL 



THE TEETH AS IliDICATOBS OF AGE. 



Their various ways of Indicating Age. The "Mark's" Twofold 

 Use. The Dentinal Star. Marks with too much Cement. 

 Tricks of the Trade. Crib-biting. Signs of Age Independ- 

 ent of the Teeth. 



THE incisor teeth of the horse, which, as before said, 

 differ "from those of all other animals by the fold of 

 enamel which penetrates the body of the crown, from 

 its broad, flat summit, like the inverted finger of a 

 glove," indicate age (1) by their cutting; (2) by their 

 growth ; (3) by their shedding ; (4) by their marks ; * 

 (5) by their change of shape ; (6) by their change of 

 color ; (7) by their length, and (8) by the degree of 

 their outward inclination. The cutting, growth, and 

 shedding (of the tushes and grinders as well as the in- 

 cisors the cutting and shedding occurring at com- 

 paratively regular periods, and the growth being grad- 

 ual), indicate age from birth till about the sixth year; 

 the marks of the lower incisors from the sixth month 

 till the eighth year; those of the upper incisors, though 



* Prof. C. S. Tomes says "the mark exists in Hipparion, but 

 not in the earlier progenitors of the horse." Prof. 0. C. Marsh 

 says : " The large canines of Orohippus became gradually re- 

 duced in the later genera, and the characteristic mark of the. 

 incisors is found only in the later forms." 



