EXPLANATION OF PLATE IX 169 



PLATE IX. The figures in this plate are enlarged drawings of the first 

 lower molar (the first or most anterior of the three big molars as dis- 

 tinct from the bicuspid pre-molars) intended especially to show : 

 (i) That the great East Indian ape, the orang-outan, has five tubercles 

 or cones on this tooth, of which three (numbered I, 2, 3) are on the 

 outer side (away from the tongue), as is seen also in the gibbon (PI. 

 VIII) ; further, that though the lower races of man usually show this 

 monkey-like character (figs. 3 and 4) (seen also in the lower jaw drawn 

 in Plate VIII), yet that frequently in Europeans (in as many cases as 

 40 out of 100 jaws examined) only four tubercles are found on this tooth, 

 as shown- in figs. 5 and 6. It seems that as compared with primitive 

 man and the " lower" existing races of man, Europeans are tending to 

 a reduction in the number of tubercles on the molar teeth as well as to 

 the " crowding out '' or reduction in size and atrophy of the last molar 

 or wisdom-tooth. As compared with the cave-man of the Neander 

 race these differences in the teeth and in the shape and size of the jaw 

 as well as more important differences in the bony skeleton (dis- 

 covered by Prof. Marcelin Boule, of Paris) are sufficient to separate the 

 modern European and the Neander cave-man as distinct species of the 

 genus Homo. The teeth in this plate are magnified to 2\ times the linear 

 dimensions of the actual specimens. Figs i and 2 show the curious 

 " wrinkling " of the enamel surface of the tooth in the orang-outan, 

 which is shown by the other molars also in that ape. The figures are 

 copied from Selenka. 



