446 QUADRUMANES. 



impression. Both premolars (ib. p.) are bicuspid, the exterior 

 cusp of the first is the largest and most produced. The true 

 molars (ib. m) are quadri-cuspid, relatively larger in comparison 

 with the bicuspids than in the Orang : the last is the smallest 

 by the feeble development of the two hind cusps. The premolars 

 as well as molars, are severally implanted by one internal and 

 two external fangs, diverging, but curving towards each other at 

 their ends, as if grasping the substance of the jaw. 



In the lower jaw the lateral incisors are broader than the middle 

 ones, but have their outer angle rounded off; they are all much 

 larger and less vertically implanted than in Man (PI. 119, fig. 1, i.). 

 The lower canines (ib. c) are two inches in length including the root ; 

 the enamelled crown is three fourths of an inch in length, and two thirds 

 across the base ; it is conical, trihedral, the outer surface convex, the 

 other two surfaces flattened or sub-concave, and converging to an 

 almost trenchant edge, directed inwards and backwards ; a ridge sepa- 

 rates the outer convex from the anterior surface : both this and the 

 posterior surface, show slight traces of a longitudinal rising. The 

 canine almost touches the incisor, but is separated by a diastema 

 one line broad, from the first premolar. This tooth (ib. p.) is larger 

 than the second premolar, and is twice the size of the human first 

 premolar ; it has a subtrihedral crown, with the anterior and outer 

 angle produced forwards, still indicating the peculiar feature of 

 the same tooth in the Baboons ; the summit of the crown terminates 

 in two sharp trihedral cusps, the outer one rising highest, and it 

 has a well developed ridge at the inner and posterior part of its 

 base. The second premolar has a sub-quadrate crown, with the 

 two cusps developed from its anterior half, and a third smaller one 

 from the inner angle of the posterior ridge. Both the lower 

 premolars are implanted by two antero-posteriorly compressed, 

 divergent fangs, the anterior one the largest. (1) The three true 



(1) M. de Blainville, in his " Osteographie des Primates" expresses himself somewhat 

 obscurely on the mode of implantation of the molar teeth of the Chimpanzee and Orang, 

 and although he alludes to faint indications of the two external holes for the premolars, 

 leaves the impression that these superior Apes diflfer from the inferior ones in the struc- 

 ture of the alveoH of the teeth. "Du reste, si les quatre parties de la couronne ne sont 

 pas aussi nettement dessinees que dans les Singes inferieures, certainement il n'y a aucune 

 indice des mammelons accessoires des Gibbons." (See, however, a demonstration of the 



