chap, ix.] TEETH : ATELES. 205 



New World Monkeys. 



*193. In the species of Cebida? and especially in Ateles supernumerary 

 teeth arc rather common, eight cases being found in 284< skulls, 

 or nearly 3 per cent, (in addition to cases recorded by others). Of 

 American monkeys belonging to other genera 92 skulls were seen, 

 all being normal. Some cases of absence of the third molar were 

 seen in Ateles, which are interesting in connexion with the fact that 

 there are normally only two molars in Hapalidse. 



Cebid.e : normal formula i J, c\, p f , m§. 



Chrysothrix, normal adults, 5. 



Cebus, normal adults belonging to about ten species, 66. 



Supernumerary molars. 



194. Cebus robustus : supernumerary molar in each upper jaw 

 giving p f , m 4; de Blainville, Laurent's Annal. d'Anat. etPhys., 

 1837, i. p. 300°, PL viii. fig. 6. 



19o. c variegatus : small tubercular molar in right lower jaw 

 behind m?. The extra tooth is cylindrical and peg-like, having 

 about Jth the diameter m?. Leycl. Mus. 8, Cat. 11. 



Ateles : normal adult skulls, belonging to several species, 60. 



Supern umerary molars. 



*196. A. pentadactylus : extra molar in series behind m d in both 

 upper and lower jaws on right side, in each case a small round 

 tooth. P. M., A, 1505. This specimen described by de Blainville 

 Laurent's Ann. d'Anat, et Phys., 1837, I. p. 300, PL VIII. rig. 5: 

 mentioned also by Geoffroy St Hilaire, Anom. d'Organ., i. 

 p. 660. 



197. A. vellerosus : extra molar on left side in lower jaw behind 

 m 3 , as a fully-formed and well-shaped tooth, but not so large as m<. 

 B. M., 89. 12. 7. 1. 



198. Ateles sp. : extra molar on left side in lower jaw. Magitot, 

 Anom. du syst. dent, p. 101, No. 6. 



Supernumerary premolars. 



*199. Brachyteles hemidactylus [a genus doubtfully distinct from 

 Ateles] : specimen from S. America having 1. upper series and all 

 lower series normal. In place of right upper p l are two teeth 

 (Fig. 37). These two teeth are similar to each other and for 

 want of space they bulge a little out of the arcade. Each is in 

 size and shape very like normal £\ having a sharp cusp and a flat 

 internal part to the crown. Both teeth are slightly rotated in 

 opposite directions, so that the cusp of the anterior is antero- 



