290 



A MANUAL OF DENTAL ANATOMY. 



of plates of dentine and enamel, fused into one tooth by 

 the cementum (see fig. 125). 



Interesting as have been the discoveries made of late 



FIG. 119 



FIG. 120 ( 2 ). 



years in Mammalian paleontology, it is not as yet by any 

 means possible to determine from what common pattern or 

 patterns all complex mammalian teeth may be considered 

 to have been derived; though the pattern of some, for 

 example, of the molars of the horse, may be traced back 

 in increasing simplicity through a number of parent forms. 

 Enough has, however, been done to indicate that by careful 

 study many complexities of pattern may be referred to a 

 few particular types, and thus may be simplified by a com- 

 parison with other allied forms, in which essential charac- 

 teristics are not masked by minor complications. Starting 



(!) Horse incisor, in longitudinal section. 



( 2 ) Horse's incisors, showing the mark at various ages. 



