86 



TOPOGRAPHICAL ANATOMY OF THE 



simplify subsequent description to dismiss the first premolar now, and 

 later describe the rest of the premolars and the molars under the 

 common and convenient name of " cheek-teeth." 



From its rudimentary character as compared with its neighbours, 

 and from its inconstancy in development, it is natural to suspect that 

 the first premolar is in process of gradual, if slow, disappearance ; and 



Incisors. 



Incisors. 



Canine. ~ 



V _ Premolars, --j 



Molars. ""/ 



Fig. 30. — The maxillary and mandibular teeth. 



that this is so is proved by the fossil remains of some of the ancestors 

 of the modern horse, in which a first premolar was relatively large and 

 obviously functional. In the mandible the tooth is frequently absent, 

 and, when present, is of \ery small size. In the maxilla it is more 

 commonly found, but it is variable in size. At its maximum develop- 

 ment the crown of the tooth is small and irregularly conical, presenting 

 some indication of the enamel-foldinsfthat is so characteristic of the 



