771 



separates the convex from the antero-internal flat surface ; both this and the posterior surface 

 show slight traces of a longitudinal rising at their middle part. The lower canine shows the 

 same relative superiority of size as the upper one, compared with that in the female Chim- 

 panzee : the canine almost touches the incisor, but is separated by a diastema one line broad 

 from the first premolar. This tooth is larger externally 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 forward, slightly 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 the second cusp being feebly indicated on the ridge extending from the 

 inner side of the first : the crown of the first has a thick ridge at the inner and posterior part 

 of its base. The second premolar has a subquadrate 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 being the largest. The three true molars are almost equal in size, the first 

 being very little larger than the last, which is the only molar as large as the corresponding 

 tooth in the black varieties of the Human subject, in most of which, especially the Australians, 

 the true molars attain larger dimensions than in the yellow or white races. The four principal 

 cusps, especially the two inner ones, of the first molar of the Chimpanzee are more pointed 

 and prolonged than in Man : a fifth small cusp is developed behind the outer pair, as in the 

 Orangs and the Gibbons, but is less than that in Man. The same additional cusp is present 

 in the second molar which is seldom seen in Man. The crucial groove on the grinding surface 

 is much less distinct than in Man, not being continued across the ridge connecting the anterior 

 pair of cusps in the Chimpanzee. The crown of the third molar is longer antero-posteriorly 

 from the greater development of the fifth posterior cusp, which however is rudimental in 

 comparison with that in the Semnopitheques and Macaques. All the three true molars are 

 supported by two distinct and well-developed antero-posteriorly compressed, divergent fangs, 

 longitudinally excavated on the sides turned towards each other. The molar series in both 

 jaws forms a straight line, with a slight tendency in the upper jaw to bend in the opposite 

 direction to the well-marked curve which the same series describes in the Human subject. 



5088. The atlas. 



There is a short process from the back part of the hypapophysis : the vertebral artery 

 pierces the transverse process lengthwise and then perforates the neural arch : the costal part 

 of the left transverse process has not been ossified : that process is represented by a short 

 parapophysis and a long diapophysis, the vertebral foramen being, nevertheless, complete. A 

 small ridge represents the neural spine. In comparison with the Orang, the breadth of the 

 atlas exceeds its antero- posterior diameter chiefly by the length of the diapophysial part of 

 the transverse process : it thus more nearly resembles that of Man in its general shape. It 

 likewise resembles it more in the minor breadth and greater length of the part representing 

 the body, in the larger and more definite surface on tne upper part for the articulation with 

 the odontoid process, and in the greater breadth and more produced margins of the hinder 

 articular processes. 



5*2 



