CHAPTER XI. 



THE TEETH AS INDICATORS OF AGE. 



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

 [jse.-The Dentinal Star.-Marks witli too mucli Cement.— 

 Tricks of the Trade. -Crib-biting.— Signs of Age ludepend- 

 ent of tlie Teeth. 



The incisor teetli of the horse, which, as before said, 

 differ '-'froiii 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 then- 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 theh- 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- 

 eisors— 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 liorse." Prof. O. C. Marsh 

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

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

 incisors is found only in the later forms." 



