28 



APKS i\Nl) MONKEYS. 



lowest races oi man, but sometimes they are 

 placed closer together. The ears in the an- 

 thropoid apes exactly resemble those of man, 

 and in them too are similarly incapable of 

 motion, while in the lower Simiie they become 

 somewhat more pointed and to a certain 

 degree capable of being moved. The outer 

 margin of the ear (the helix) is rolled in as 

 in man, and only the inferior lobe is less 

 developed and less clearly marked off. 



The jaws and dentition demand a closer 

 examination. Since these are in general 

 more powerfully developed than in man, the 

 maxillae and gums are proportionally longer 

 and narrower, more elliptical than circular in 

 form, the lower jaw mostly higher than in 

 man, but its two halves always, as in man, 

 completely fused. I mention this character 

 here expressly because it forms an essential 

 distinction between the Simla; and the 

 Prosimii, in which latter the two halves of 

 the lower jaw are connected in such a manner 

 that they can easily be separated. 



A projecting chin, what is called in more 

 technical language a mental process, is alto- 

 gether wanting in the Simise; but this 

 feature even in human jaws, and especially in 

 childhood, is often only slightly developed. 



The premaxilla, which carries the upper 

 incisors, becomes fused in man very early, 

 even during embryonic existence, with the 

 adjoining bones, while in the Simian, on the 

 other hand, the fusion takes place later, 

 mostly at the time of the emergence of the 

 permanent molars. 



If we now consider the dentition itself, the 

 first thing that strikes us is that in all the 

 Simla;, but especially in males and in those 

 genera which incline to the carnivorous type, 

 the canines rise with their crowns above the 

 masticating surface of the other teeth and fit 

 into a more or less developed gap or diastema 

 in the opposite set of teeth. AW the other 

 teeth lie close together with their crowns on 

 the same level. In man large canines occur 

 but seldom. 



As already mentioned in the Introduction, 

 the milk dentition demands special consider- 

 ation, inasmuch as this represents the inheri- 

 tance which the creature has derived from its 

 ancestors. 



With respect to the milk dentition the 

 .Simla; are divided into two great groups. 

 All the Old World Simiee have twenty milk 

 teeth, like man, namely, two incisors, one 

 canine, and two premolars in each half of 

 each jaw. All the New World forms, on the 

 other hand, have twenty-four milk teeth, 

 there being in them an additional premolar 

 with the same incisors and canines. Through 

 the development of the permanent dentition 

 there arises a division among the New World 

 forms, for while in all except the Clawed 

 Monkeys, or Arctopitheci, three molars 

 emerge in each half of each jaw, in these 

 there are only two, the so-called wisdom-tooth, 

 the last in the series, never appearing in them. 

 We thus obtain the following dental formu- 

 las:— 



Milk Dentition. 



iNcrsoRs. Ca.mnes. Premolars. Total. 

 Man and Old I 2 i 2 



World Simiaj, ) -. , -> ~ "^ 



New World 1 

 Simiac', J 



Arctopitheci, 



24 



24 



Permanent Dentition. 



Incisors. Cantnes. Premolars. Molars. Total 



Although, then, the Arctopitheci have 

 exactly the same number of teeth as the Old 

 World .Simla; and man, yet they belong to 

 the general American type in that they differ 

 from these, as all the other American forms 

 do, in the numl)er of their premolars. 



'I he fundamental structure of the teeth is 

 exactly the same as in man. The incLsors 



