DETERMINING THE AGE OF ANIMALS 193 



represents a cross section of the pnlp cavity, pnts in its appear- 

 ance. It first takes the form of a Ijrown or dark streak, and 

 hiter a circuhir dark spot which gradually increases in size with 

 the wear on the tooth and the age of the animal. 



The following changes in the shape and appearance of the 

 incisor teeth of the average horse occur in the different years. 

 Unless otherwise mentioned, the statements made regarding the 

 appearance and wear on the table surfaces apply to the lower 

 incisor teeth. 



Six Years. — The table surfaces form the most accurate guide. 

 The cups of the nippers tend to an oval form. The corner teeth 

 have been in wear one year at this time. The cup is deep and 

 the posterior margin may show little wear. It is not uncommon 

 to meet with corners that possess irregularly developed tables, 

 and have cups with posterior margins that are thin and do not 

 come into wear until later. For this reason, it is not best to 

 depend on the appearance of the corner teeth alone. 



Seven Years. — The teeth are usually whiter than the previ- 

 ous year. The profile of the upper corner teeth shows a notch 

 in the posterior portion of the table surface. This is due to the 

 superior corners overhanging the inferior corner teeth pos- 

 teriorly, resulting in this portion not wearing away. This notch 

 is sometimes slightly in evidence the previous year. The cups 

 in the corners are smaller and the worn surface larger than at 

 six. The nippers show oval table surfaces and the dividers are 

 beginning to take on this shape. The shifting of the cups toward 

 the posterior portion of the tables of the nippers and dividers 

 is noticeable. 



Eight Years. — As viewed from the side, the profile of the 

 teeth shows a very noticeable increase in the ol)li(|uity with which 

 they meet. The posterior borders of the corners show consider- 

 able wear. The notch in the superior corners is still present, 

 but as the teeth come more nearly in apposition it may begin to 

 disappear. All of the inferior tables are level. The nippers and 

 13 



