1911] The Ottawa Naturalist. 23 



double-rooted third premolar are self-contained in distinct, 

 clean-cut peripheral margins without any elevation of the bone 

 externally or internally between them, and are separated only 

 by a sharp-edged septum of bone which is at the same level as, 

 and contributes equally to, the margins of both alveoli. Between 

 the alveolus for the first premolar and the anterior one of the 

 third is a space measuring 6 mm. 



Diameter of alveolus of first premolar: Mm. 



Antero-posterior 13 



Transverse 8 



Diameter of anterior alveolus of third premolar: 



Antero-posterior 7.5 



Transverse 6 



Diameter of posterior alveolus of third premolar: 



Antero-posterior 10 . 5 



Transverse 7 



Of the incisors the third is much the largest, and the second 

 is slightly smaller than the first. The fourth premolar has a 

 well-developed inner cusp in line with the mid-length of the 

 tooth, adding to its breadth and causing the cross section of the 

 crown to be subtriangular in outline, the exterior surface of the 

 crown exceeding in length the two inner and equal sides. The 

 first molar is subquadrangular in outline, its breadth nearly 

 equalling its maximum antero-posterior diameter which is at 

 the outer side of the crown. The second molar is broadest in 

 front, and narrows rapidly backward; its maximum breadth is 

 equal to two-thirds of its length. All the teeth are much worn. 



Diameter of first incisor: Mm. 



Antero-posterior 12.5 



Transverse 8 



Diameter of alveolus of second incisor : 



Antero-posterior 13 



Transverse 7 



Diameter of third incisor: 



Antero-posterior 17 



Transverse 18 



Diameter of fourth premolar: 



Antero-posterior 22.5 



Transverse 17 



Diameter of first molar: 



Antero-posterior 27 



Transverse 25 



Diameter of second molar : 



Antero-posterior 37.5 



Transverse 25 



