325 



in the upper and lower jaws are called the "firsts"; the 

 next two, on either side, the " seconds " ; and the next 

 two, or corner teeth, the " thirds." It may be well to 

 explain here that in order to render the principles of 

 the system more intelligible to the uninitiated, the 

 markings indicating grooves, notches, indentations, etc., 

 shown on the diagrams, are much more distinct than 

 they actually appear on the natural teeth of horses, so 

 that, in addition to a theoretical knowledge, long and 

 careful experience is absolutely essential in order to 

 determine the correct age of horses. 



Colt teeth are generally smooth and grooveless, 

 and some foals have the firsts at birth. In the course 

 of four weeks the seconds develop, and at twenty-four 

 weeks the thirds. When the foal is about ten months 

 old all the teeth are level. The teeth have indentations 

 or cups in their crowns, which wear out respectively 

 as they were developed, at intervals of about six 

 months, so that at two years of age the teeth are all 

 flat on their crowns. (Figs. 50, 51, 52. 53, 54, and 55). 



In the horse teeth which follow, the firsts develop 

 at two and a-half years of age ; the seconds at three 

 and a-half ; the thirds at four and a-half ; and at five 

 all the teeth are level. The horse teeth displace the 

 colt teeth from two and a-half years of age till four 

 and a-half in regular rotation. Like colt teeth, the 

 horse teeth have deep cups in their crowns, and they 

 generally appear grooved on the surface. At six years 

 of age tho cups leave the firsts ; at seven, the seconds ; 

 at eight, the thirds ; and at nine all the crowns of the 



