THE TEETH 167 



The upper lateral incisor is smaller than the mesial, which it for 

 the most part resembles. The lateral angle of the cutting edge of 

 the crown is rounded off, and the cingulum is more prominent than 

 in the upper central incisor. 



The lower mesial incisor is smaller than the lateral, and narrower 

 than the upper mesial incisor. The cingulum, if present, is not 

 well marked. The root is much compressed laterally. 



The lower lateral incisor is larger than the mesial, which it for 

 the most part resembles. The presence of a cingulum is rare. The 

 root is longer than that of the central incisor, and on each flat- 

 tened lateral surface there may be an indication of a longitudinal 

 groove. 



The Canines. — There are four canine teeth — one in each upper 

 jaw, and one in each half of the lower jaw. 



The crown of a canine tooth is larger than that of an incisor. 

 It is somewhat conical, and terminates in a cusp, from which cir- 

 cumstance the canine teeth are known as the cuspidate teeih. The 

 labial surface of the crown is convex. 



In the upper canines the lingual surface of the crown usually 

 presents a shght median ridge, which extends from the cusp to a 

 ridge which represents the cingulum. The root is long, thick, and 

 almost round. 



The lower canines have no median ridge on the lingual surface, 

 which may be sUghtly concave. The citigulum is absent. The 

 root is shorter than in the upper canines. 



The Bicuspids, or Premolars. — There are eight bicuspid teeth — 

 two in each upper jaw, and two in each half of the lower jaw. 



Upper Bicuspids. — The crown is quadrilateral, and its labial 

 border is longer than the lingual. It has two cusps — ^labial and 

 lingual — both of which are prominent. The labial cusp is the 

 larger and broader of the two, and the cusps are separated by a 

 deep transverse fissure. The labial and lingual surfaces of the 

 crown are convex, and there is no cingulum. The root is single, 

 much compressed laterally, and usually marked on either side by 

 a longitudinal groove. 



The first upper bicuspid has frequently two slender fangs. This 

 occurs so often that it may be regarded as the normal condition 

 in that tooth. 



The second upper bicuspid differs from the first in the following 

 respects: (i) Its crown is larger, and approaches more nearly the 

 molar type; and (2) its lingual cusp is larger and broader than that 

 of the first upper bicuspid, so that its labial and lingual cusps are 

 of nearly equal size. 



Lower Bicuspids. — ^These teeth are smaller than the upper 

 bicuspids. The labial cusp has an inclination inwards towards the 

 mouth, and the lingual cusp is depressed. The cusps are connected 

 by a lou-lying ridge. The root is single, round, and tapering. 



The second lower bicuspid differs from the first in the following 

 respects: (i) Its crown is larger, and approaches more nearly the 



