MANUAL OF MODERN FARRIERY 



this regular wear which is termed "losing the 

 mark " (see fig. 4). The obliteration of the mark 

 has frequently taken place by the time the corner 

 teeth are beginning to appear. It must be dis- 

 tinctly understood, that in speaking of the marks 

 in the tooth we constantly refer to the incisors of 

 the under jaw, except when otherwise expressed ; 

 and the ages of all horses, except thoroughbreds, 

 are reckoned from May. 



When an incisor tooth has commenced wearing? 

 and its two edges are parallel, the table exhibits 

 two bands of enamel, the one exterior, that sur- 

 rounds the tooth, which is termed the casing 

 enamel ; the other internal, only surrounding the 

 cavity, and this is called the central enamel (see 

 Plate iv, figs. 3 and 5). The incisor teeth of the 

 lower jaw always wear more quickly than those 

 of the upper, and uniformly more regular. The 

 reason of this has never been satisfactorily ac- 

 counted for, but it is certainly very remarkable. 

 From this fact it is obvious that it is more difficult 

 to judge of the period of obliteration of the mark 

 in the upper jaw. In the lower jaw the marks of 

 the central incisors are always obliterated at about 

 ten months, in the dividers or second teeth at one 

 year, and from the corner or inner incisors varying 

 from fifteen months to two years. 



By this time the marks of the upper nippers have 

 become almost entirely obliterated, so that at two 

 years old the cavities in all the temporary incisor 

 teeth have disappeared. 



At this period the crowns of the incisors become 

 insensibly smaller, and with their base necked. They 

 also assume a yellowish-brown aspect, soon after 

 which they loosen and almost entirely lose their 



