456 HUMAN DENTITION. 



I 



division notched off posteriorly, and the inner cusp is relatively 

 larger than in the Chimpanzee : the first upper molar of the 

 Orang is simply bicuspid, but is larger than in the Chimpanzee. 

 The second molar of the Human child could scarcely be distin- 

 guished from that of the young Chimpanzee : both are quadri- 

 cuspid, and the same oblique ridge crosses the grinding surface from 

 the antero-internal to the postero-external tubercle ; but the pointed 

 summits of the two outer cusps are a little more produced in the 

 Chimpanzee. The second molar of the Orang besides its larger 

 size, has the four tubercles better defined, and the oblique ridge 

 less developed. 



The lower deciduous incisors of the anthropoid Apes differ 

 from those of the Human subject in their superior size, greater 

 relative thickness, and the lateral incisor more particularly by the 

 rounding off of the outer angle. The lower canine of the Chim- 

 panzee has a larger, longer, and more pointed crown with a sharp 

 posterior edge: this is less marked in the canine of the Orang, 

 which is larger and thicker than in the Chimpanzee : the crowns 

 of the upper and lower canines are more obliquely opposed, the 

 lower one being more advanced in those Apes than in the 

 Human subject. The first lower deciduous molar of the Human 

 subject has four tubercles and a small anterior ridge, and is 

 larger than that of the Chimpanzee, which supports a single large 

 pointed cusp, and a posterior ridge : the first molar of the Orang 

 has a similar simple crown, but is as large as that of the child. The 

 second molar is of equal or superior size in the Human to that 

 in the Chimpanzee, but it supports three outer and two inner 

 cusps, while in the Chimpanzee it has but four cusps : in the 

 Orang the fifth external and posterior tubercle is feebly indi- 

 cated. The deciduous molars of the Human subject, as in the 

 Chimpanzee and Orang, have each three fangs in the upper and 

 two in the lower jaw. 



The differences brought out by the foregoing comparisons, though 

 less striking than those exhibited by the permanent teeth, will be ap- 

 preciated by the philosophical Anatomist as yielding more certain evi- 

 dence of the essential distinction of the Bimanous species : he will 

 perceive that they are not due to mere adaptive developments, but are 



