114 THE STRUCTURE OF THE HORSE. 



food between the molar teeth. The horizontal por- 

 tion of the jaw, long, straight, and flattened from side 

 to side, carries the great molar teeth, and gradually 

 narrows towards the symphysis, where it expands 

 laterally, to form, with the united opposite ramus, 

 the wide, semicircular, shallow alveolar border for 

 the lower incisor teeth. 



The Teeth. 



The next parts to which attention may be called 

 are the teeth, which in the horse, though founded 

 upon the same general type as the primitive Ungu- 

 lates of the Eocene period, have undergone a remark- 

 able amount of specialization, fitting them in an 

 eminent degree for the purpose they have to fulfill. 



Number of the Teeth. — For convenience of descrip- 

 tion teeth are divided, according to their situation in 

 the mouth and other characters, into four sets, called 

 (beginning from the front) incisors, canines, premo- 

 lars, and molars. As mentioned in the first chapter, 

 all the early Ungulate mammals, without exception, 

 had on each side, above and below, three incisors, 

 one canine, four premolars, and three molars — that 

 is, eleven on each side above, and eleven below, or 

 forty-four altogether. The modern horse has nearly, 

 if not quite, this full number. The front teeth, or 

 incisors, are the same — six above and six below, tak- 



