QUADRUMANA. 



199 



apices of the large laniaries respectively of 

 the opposite jaw, when the mouth is closed. 



In the description of all these peculiarities 

 of the skull of the Chimpanzee, I have been 

 somewhat lengthy, wishing to give an abstract 

 of the excellent paper by OWEN * ; and I 

 deemed it necessary to do so, because the 

 Chimpanzee may be considered as the typical 

 link of a chain uniting mankind with the 

 lower animals. By the minute exhibition of 

 all its characters, it is evident that it has a 

 great deal of analogy with the form of man, 

 but that, on the other side, it is removed 

 from man by its more imperfect structure. 

 This inferiority becomes gradually more ap- 

 parent in the skull of the other monkeys, as 

 may be seen by the brief statement of their 

 principal forms. 



In the skull of the Orang-cetan (Jig. 117) 



Fig. 117. 



Skull of the Orang-cetan. (After Owen.) 



the approximation to the Carnivora appears 

 principally in the interparietal and occipital 

 crests, which, as I have proved in my Reck. 

 cTAnat. Comp. sur le Chimpanse, increases with 

 the general growth of the animal ; in the less 

 large interorbital space ; in the sometimes 

 single, sometimes double nasal bone, which 

 never projects, as in the Chimpanzee, beyond 

 the plane of the nasal process of tlie superior 

 maxillary bones ; in the facial suture of the 

 intermaxillary bone, remaining till the per- 

 manent teeth are almost fully developed ; in 

 the more prominent maxillary and intermaxil- 

 lary bones ; in the stronger teeth ; in the 

 higher and longer lower jaw ; and in the more 

 depressed chin. It is remarkable that the 



* Fearing I might give an inaccurate account, I 

 have employed, for the most part, the very words of 

 that experienced anatomist, feeling persuaded that, 

 especially for a foreigner, it would be difficult to 

 give a more elegant and more accurate description 

 than he has done. I confess myself guilty of the 

 same plagiarism in some other points of the osteology 

 of the Chimpanzee and Orang-cetan. 



analogy with the human form is more striking 

 in the young than in the old Chimpanzee 

 and Orang-cetan. In the old, the face, and 

 principally the maxillary bones, grow larger, 

 by which the brutish appearance of the skull 

 becomes greater. On the first aspect, this 

 seems a deviation from a general rule, but it is 

 not so; for in the human subject similar 

 modifications of the skull by age may be 

 observed. In advancing age the face of the 

 child becomes gradually larger and higher, 

 and the receptacle for the brain proportionally 

 smaller, in the same manner as in the Orang- 

 cetan, but in a less degree. 



In the skull of the Siamang (Jig. ] 18), the 



Fi. 118. 



Skull of the Siamang. ( Original from the museum 

 of Prof. G. Vrolik.} 



analogy with the human form is, in some 

 parts, greater than in the Orang-cetan. The 

 superciliary ridges, and the semicircular bound- 

 ary for the insertion of the temporal muscle, 

 are much developed, and the skull is very 

 flat, as in the Chimpanzee, but the interorbital 

 space is large, as in the human subject; the 

 nasal bone is double in young animals, single 

 in the old, but much broader than in the 

 Chimpanzee or Orang-cetan; the facial part of 

 the skull is broad, and not so prominent as in 

 the two preceding species; the chin has a 

 vertical direction and rounded form ; the 

 coronoidal apophysis of the lower jaw is not 

 very high. By all this the skull of the 

 Siamang approaches to that of the human 

 subject, but it shows nevertheless its infe- 

 riority by the foramen occipitale magnum being 

 placed more backwards. In this and the 

 other Gibbons a striking character is given, by 

 the swollen appearance of the posterior wall 

 of the orbit, produced by the convexity of 

 the orbital part of the zygomatic bone. The 

 ala magna of the sphenoid bone contributes 

 nothing to the formation of the orbit, being 

 bent backwards. The superior margin of the 

 squamous portion of the temporal bone is 

 straight, as in the Chimpanzee, the Orang-cetan, 

 and, in general, as in all the monkeys. 



The Semnopitheci form a sort of transition 

 from these anthropomorphous species to the 

 lower monkeys. Their face is not very pro- 

 minent; the facial suture of the intermaxillary 

 bone continues to exist in the adult, but dis- 

 appears in the very old ; the coronal suture is 

 prolonged in a point between the two parietal 



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