VETERINARY DENTAL SURGERY. 247 



At ten years the central enamel of the central 

 incisors has disappeared, and that of the lateral 

 incisor is round and near the posterior border. The 

 central enamel of the corner incisors is oval. 



At eleven the central enamel of the lateral in- 

 cisors has disappeared, and that of the corners is 

 round. 



At twelve the central enamel of the corner 

 incisors has disappeared. 



At thirteen the table surface of the central in- 

 cisors has become triangular. 



At fourteen the table surface of the lateral incis- 

 ori are triangular. 



At fifteen the table surface of the corner incisors 

 is triangular. 



At sixteen the diameter of the table surface, from 

 before back, exceeds the lateral diameter in the cen- 

 tral incisors. 



At seventeen the diameter of the table surface, 

 from before back, exceeds the lateral diameter in the 

 lateral incisors. 



At eighteen the diameter of the table surface, 

 from before back, exceeds the lateral diameters in 

 all the incisor teeth. 



Gray hair around the eyes and over the face, 

 and depressions behind the orbits, are indicative of 

 advanced age and help one to form a pretty correct 

 idea of the age of the animal. Sometimes fraud is 



