316 ANATOMY OF VERTEBRATES. 



d i. . .. d 4, in place, together with the first of the permanent true 

 molars, m, i ; the germs of the rest of the permanent teeth are 

 exposed in the upper jaw. 



In the Catarhine division of the order, the first or deciduous 

 dentition consists of- 



.2.2 1.1 2.2 

 '22 ;C l7T ;m 2^ = 2 - 



The two milk molars are displaced and succeeded vertically by 

 the two bicuspid premolars, and are followed horizontally by 

 three true molars on each side of both upper and lower jaws. 

 The permanent formula in all the Old World Qnadrumana is 



.2.2 1.1 2.2 3.3 



The incisors have always a shape conformable to their name, 



250 but are very thick and strong ; 



in the upper jaw the middle are 

 larger than the lateral ones, 

 and both are larger than those 

 below. The canines are coni- 

 cal, pointed, with trenchant pos- 

 terior margins, always longer 

 than the adjoining teeth, and 

 acquiring, in the males of the 



Catarhine dentition (Papto). T i i r\ , i 



great Joaboons and Urangs, the 



proportions of those teeth in the Carnivora. The Mandrills Papio 

 maimon (fig. 252) have these dental weapons most formidable for 

 their size and shape ; especially the upper pair, which descend 

 behind the crowns of the lower canines, and along the outside of 

 the first lower premolars, the crowns of which seem as if bent 

 back by the action of the upper canines ; the anterior longitudinal 

 groove of these teeth is very deep, their posterior margin very 

 sharp. A long diastema divides the upper canine from the inci- 

 sors, a short one separates it from the premolars ; these and the 

 three true molars are arranged in a straight line. 



In the Orang-utan (Pit/iecus Wiirmlii), vol. ii. p. 534, fig. 

 355, the thickness of the base of the crown of the upper middle 

 incisors equals the breadth of the same ; and they are double the 

 size of the lateral incisors. The abraded surface of the front 

 incisors in the old Orang forms a broad tract extending obliquely 

 from the cutting edge to the back part of the base of the crown ; 

 the lateral incisors are more pointed, the outer angle being ob- 

 liquely truncated ; a vacant space of their own breadth divides 

 them from the canines. These, in the male Orang, have a long 



