426 MAMMALIAN ANATOMY 



groove. If the concave surface of the tooth be held uppermost, the 

 fang away from the student, the longer and straighter border of the 

 crown will be on the side to which the tooth belongs. 



The lower incisors may be distinguished from the upper by the 

 absence of the posterior groove ; the third from the others by the 

 distinct outer cusp. If the tooth be held with the concave side upper- 

 most, the cutting edge toward the student, the more prominent part of 

 the cutting edge will be on the side to which the tooth belongs. 



The upper canine may be distinguished from the lower by its 

 straighter and relatively longer crown. If the flatter surface of the 

 crown be held uppermost, the fang away from the student, the straight 

 border of the crown will be on the side to which the tooth belongs. 



The lower canine differs from the upper by its shorter, more 

 strongly curved crown. If the concave posterior border of the crown 

 be held uppermost, the fang away from the student, the tip of the 

 crown will curve toward the side to which the tooth belongs. 



The first upper premolar may be known by its small size and its 

 triangular crown. If the flatter side of the crown be held uppermost, 

 the fang away from the student, the longer border of the crown will 

 be on the side to which the tooth belongs. 



The second upper premolar may be distinguished by its larger 

 prismatic posterior root. If the side which has the convexity in the 

 cingulum be held uppermost, the fangs away from the student, the 

 large fang will be on the side to which the tooth belongs. 



The third upper premolar has three fangs and a cutting blade. If 

 the flat side of the cutting blade be held uppermost, the fangs away 

 from the student, the large fang will be on the side to which the tooth 

 belongs. 



The single upper molar is readily distinguished by its transversely 

 broad and flat crown and its two fangs. If the prominent outer end 

 be held uppermost, the fangs away from the student, the curved crest 

 on the crown from the middle to the outer end will be on the side to 

 which the tooth belongs. 



The first lower premolar differs from the second in its smaller 

 size and in the less development of the posterior part of the crown ; 

 it differs from the second upper premolar in the almost equal size of 

 its fangs. If the side of the crown which is more convex from above 

 downward and flatter from before backward be held uppermost, the 



