448 QUADRUMANES. 



a small anterior tubercle, which feebly indicates the great ex- 

 tension of that part of the crown of its successor. The deci- 

 duous canines have short, straight, conical crowns ; differing in 

 form and still more in size from the formidable sub-compressed 

 curved, piercing and trenchant teeth which succeed them : es- 

 pecially in the male sex, which in this respect diverges farther 

 from the immature type than does the female. The permanent 

 incisors are also much larger than the deciduous ones, and 

 especially so in the Chimpanzee and Orang in which I shall 

 here describe the order of development and succession of the 

 permanent teeth ; reserving the special comparison of their de- 

 ciduous teeth with those of the Human subject for the following 

 Chapter. 



The deciduous teeth are shown in situ in PL 1 20, in the young 

 of both these highly organised Apes, at the period when the first 

 permanent true molar (m 1) has cut the gum, on each side of both 

 jaws. The next permanent teeth that appear are the middle 

 incisors of the lower jaw, the corresponding deciduous teeth 

 being the first that are shed. Then the two large middle upper 

 incisors {i 1) come into place : these, in the living Orang of the 

 Zoological Gardens (1) occasioned the displacement not only of 

 the middle but the lateral milk incisors ; whilst in the skull of 

 the young Orang, which I have described and figured in the 

 Zoological Transactions, (2) the middle permanent incisors and the 

 lateral deciduous ones are both in place in the upper jaw. The next 

 permanent tooth that cuts the gum is the second true molar of the 

 lower jaw, which is followed by the corresponding tooth of the upper 

 jaw (m2). In about eight months after the lateral inferior incisors 

 make their appearance above the gum, and then those of the upper 

 jaw {i 2). The bicuspids {p. 1 and p. 2) are the next teeth which 

 come into place. They are followed by the third true molar teeth. 

 The great canines (c) are the last of the permanent series which 



diately upon the question of distinction between Man and the Ape : I have, therefore, de- 

 voted two plates (118 and 119) to the ilhistration of the striking difference which the 

 lowest as well as the highest races of the Human species present as compared with the 

 Chimpanzee, in the insertion of the premolar teeth in both jaws. 



(1) Zoological Proceedings, 1843, p. 123. 



(2) Vol. ii, p. 166, pi. 30. 



