Eleven Years 

 Upper Incisors 



Ten ftAk:3 

 Upper Incisors 



Fifteen tears 

 Lower Incisors 



Passing to the permanent incisors in the upper jaw at nine years tlie 

 central pairhave almost completely lost their mark. At ten those adjoining 

 these have reached the same condition, while at eleven the marks have 

 about vanished from all of the permanent incisors. It will be noticed that 

 as tlie age advances the appearance of the worn tables assumes a more tri- 

 angular form. 



Five Ye.ars 



Twenty One Years 



Comparison of a five-year-old moutli with one that is twenty years old, 

 showing the marked contrast that develops, as age advances, in the slope of 

 the teeth as viewed from the side. To Goubaux and Barrier's "Exterior of 

 the Horse" the author is greatly indebted for the prints of horses' teeth 

 which have been shown. These have been modified somewhat to bring out 

 more clearly the necessary distinctions. 



