84 THE HORSE 



himself thoroughly acquainted with the difference between 

 temporary and permanent incisors. There need be no 

 difficulty about this if visits can be paid to the horse 

 slaughterers, as specimens of the incisor teeth in the lower 

 jaw can usually be obtained from the carcases at different 

 times ; in fact, most horse slaughterers will, if asked, 

 reserve specimens for anyone wanting these. Mouths 

 showing the teeth at various ages can thus be obtained 

 for comparison. The molar teeth are, of course, not 

 required. An incisor tooth corflprises the following parts, 

 the nominal differentiation of which is essential in order 

 to understand the changes which take place in the teeth : 

 That part of the tooth which projects above the gum is 

 called the crown, below which is the neck of the tooth, 

 this being encircled by the gum. The fang fixes the tooth 

 in the socket and is covered by a cement substance. The 

 face of the crown is covered by enamel. The cutting edge 

 of the tooth is known as the table, and it is by the changes 

 through wear which take place on the table that we are 

 enabled to form a fairly accurate estimate of any particu- 

 lar animal's age, exceeded only b}^ absolute proof of date 

 of birth. To begin with, an incisor tooth is elongated, or 

 rather, elliptical on its cutting edge. The table is en- 

 circled by enamel, which forms the outer boundary of the 

 tooth. This is the " outer enamel ring.'' As the table 

 forms there is another enamel ring, and this is spoken of as 

 the " inner enamel ring," which encircles a central 

 " mark " or depression, known as the " infundibulum " — 

 a dark mark arising through particles of dirt insinuating 

 themselves into the small depression previousl}^ referred 

 to. 



By horse dealers this mark is called the "bean." As 

 the wear of the tooth proceeds the table alters in shape, 

 and so does the inner enam.el ring, until the latter and the 

 '' mark " are finally obliterated, as happens in old age. 

 An incisor tooth is mainly composed of a substance known 

 as dentine, and it is this which forms the bulk of the table. 



