THE DENTAL SYSTEM. 59 



sheep ; while in other domesticated animals, as the elk, deer, 

 goat, common ox and sheep, the horns also present legible in- 

 dications of the progress of time. 



" Keference to the teeth to ascertain the horse's age is not 

 by anv means a practice of recent origin. Xenophon, in his 

 well-known work on horsemanship, allndes to it as an estab- 

 lished custom nsed in the selection of cavalry for the Grecian 

 armies ; he properly advised a rejection of such horses as have 

 lost the dental mark. The same facts are subsequently noticed 

 b}^ Yarro, Columella, Yegetius, and other Roman writers. 



"The horse, when full mouthed, possesses forty teeth — 

 twenty in each jaw. They are nameH from their use, position 

 and character. Those in the front of the mouth, whose office it 

 is to gather the food when grazing, are termed incisors, or more 

 properly nippers. They are twelve in number, six above, and 

 six below ; they do not overlap- each other, as is the case in 

 man, but meet in a broad tabular surface. From these teeth is 

 principally deduced the age of the animal. For the sake of 

 desci-iption, they are usually ranged in pairs, as they appear, 

 and the first pair is called the central, the second the dividers, 

 and the third the corner nippers. The tushes or ccmines come 

 next, one above and one below on each side. They are of a 

 jjointed form, and are convex on the outer side, and slightly 

 concave on the inner surface. They scarcely ever appear above 

 the gums in mares, although their rudiments may be discovered 

 on dissection, imbedded in the maxillary bones. They are con- 

 sequently regarded as sexual distinctives. It is difficult to as- 

 sign their use ; their position precludes the possibility of their 

 being used as weapons of offence or defence. They may be 

 viewed as a link of uniformity so commonly traced in the ani- 

 mated world. The grinders or molars are twenty-four in num- 

 ber. They are teeth of great power. By them the food is 

 comminuted, and prepared for the digestive action of the 

 stomach. In order to fit them for their office, they possess ad- 

 ditional interlayers of enamel, which prevent their too rapid 

 wear. The arrangement and number of the horse's teeth may 

 be represented by the subjoined dental formula. 



" Incisors, | ; canines, in the male only, \ ; molars, ^^^^^ 40. 

 In common with most animals, the horse is provided with two 



