chap, ix.] TEETH : ATELES. 207 



that is to say, an extra premolar on each side in the upper jaw, the 

 lower jaw being normal. The four upper premolars are perfectly 

 formed, large teeth, in regular series on both sides. As a conse- 

 quence the lower canines bite on and partly behind the upper 

 canines. There was nothing to suggest that any one of these 

 teeth was supernumerary, rather than another (Fig. 38). B. M.. 

 1.214, b. 



Supernumerary incisor. 



201. Ateles ater : specimen from Peruvian Amazon : in right 

 upper jaw there is a large alveolus for i 2 , which is gone, while a 

 third incisor stands between this and the canine. This third 

 incisor bites on lower canine, and lower p 1 of the same side bites 

 in front of the upper canine. B. M., 1108, d. 



202. Ateles paniscus : extra incisor in upper jaw. Rudolphi, 

 Anat.-phys. Abh., 1802, p. 145. 



Absence of molars (cp. No. 209). Inasmuch as^f, m% is the 

 normal formula for the Hapalidae, the following cases of absence of 

 m 3 in Ateles are interesting. There was in no case any doubt that 

 the skulls were fully adult, and there was no suggestion that the 

 absent tooth had been lost. 

 *203. Ateles marginatus : specimen from the Zoological Society's 

 menagerie, bones rough and unhealthy-looking, but skull well 

 formed and certainly not very young, has no m 3 in either jaw, giving 



3 3 2 2 



the formula p — , m~ — -, as in Hapalidse. There is no space 



in the jaw behind m 2 , and in the upper jaw the bone ends there 

 almost abruptly. 



204. A. melanochir : Caraccas specimen, having no posterior m 2 

 on either side in upper jaw. The lower series normal, but the 

 jaws are somewhat asymmetrical, so that the lower posterior right 

 m 3 is behind the level of its fellow of the other side. B. M., 4s. 

 10. 26. 3. 



205. A. variegatus : wild specimen, having lower m 3 absent on 

 both sides. Left *f is also absent, but has been almost certainly 

 present. CM., 1098, B. 



Mycetes : of various species, adult normals, 81. 



Supernumerary molar. 



206. M. niger : supernumerary molar in the right upper jaw. The 

 arrangement is peculiar. So far as m- the teeth are normal. 

 Behind and in series with m 2 there is a large tooth, a good deal 

 larger than the normal m 3 , and having rather the form of m* than 

 of m 3 . Its form is, however, not precisely that of m 2 , for the 

 middle or fifth cusp is rather anterior to the centre of the tooth. 



