THE TEETH OF MAN. 



edge of the gum, and intervenes between the edges of the 

 bony sockets and the edge of the enamel ; the root is that 

 part which is enclosed within the bony socket, and is 

 covered by cementum. ^ x " 



Of these it is to be remarked that the " neck," although 

 a convenient and necessary term for descriptive purposes, 

 marks an arbitrary division of less importance than that 

 expressed by crown and root j also that although this divi- 

 sion into three parts can be made in the case of socketed 

 teeth of limited growth, no such distinction of parts can 

 be made in teeth of perpetual growth. 



Special names have been applied to the various surfaces 

 of the crowns, as, owing to the curvature of the alveolar 

 border, terms which had reference to front, back, or sides 

 would, in different parts of the mouth, indicate different 

 surfaces, and so lead to confusion. 



The lips and tongue and the median line of the mouth, 

 however, are not open to this objection, so the surfaces 

 which are directed outwards towards the lips are called 

 " labial ; " and those inwards towards the tongue " lingual ; " 

 the interstitial surfaces are called " median " and " distal," 

 the word median being applied to the surface which would 

 look towards the middle line of the mouth had the alveolar 

 border been straightened out. In other words behind the 

 canine, the " median " is equivalent to anterior, and " distal " 

 to posterior surface. 



Forms of the several Teeth. It is usual to speak of 

 the teeth as being modified cones, and to attribute their 

 variations to deviations from this typical shape. In a broad 

 sense this may be true of the simplest teeth, such as are met 

 with in some fish and reptiles and monophyodont mammals, 

 which are little more than simple cones ; but there are in- 

 dications which would point to something more complex 

 than this as the fundamental form of a mammalian tooth, 

 for even among the monophyodonts, as I have elsewhere 



