14 A MANUAL OF DENTAL ANATOMY. 



Lower canines are less pronounced in form than the cor- 

 responding upper teeth : the point is more blunted, the 

 fang shorter, the perpendicular labial ridge not being 

 traceable, and the want of symmetry between the mesial 

 and distal halves of the crown less marked. The lingual 

 surface has perhaps a greater tendency to concavity. 



Fremolars, Bicuspids, are eight in number, two on each 

 side of both upper and lower jaws, and they correspond to 

 the third and fourth premolars of the typical mammalian 

 dentition, the first and second premolars not being re- 

 presented in man. 



Upper Premolars. The crown, as seen looking upon its 

 grinding surface, is roughly quadrilateral, its outer or 

 lingual border being, however, larger and thicker than its 

 inner, and the teeth are carried round the curve of the 



FIG. 5 0). 



alveolar border mainly by means of this difference in size 

 in the external and internal portions of the canines and the 

 two bicuspids. 



As is implied by its name, the crown has two cusps, of 

 which the outer is the larger and stouter, and broader. 

 The outer and inner surfaces (labial and lingual) are convex 

 and smooth, with no basal ridges at the edge of the gums. 

 The inner and outer cusps are not joined by a transverse 

 ridge ; instead of this there is a deep transverse fissure ; in 

 point of fact the cingulum has been elevated to form the 

 inner cusp, and forms slight elevations bordering the anterior 



(*) Grinding surface of an upper bicuspid. 



