Comparative Osteology of the Orang Utan and Chimpanzee, 459 



temporal bone joins tlie frontal, and separates the parietal and sphe- 

 noid bones, as in the young. The condyloid processes are propor- 

 tionately smaller than in the human subject, and their articular sur- 

 face is directed more outwardly. The foramen magnum is thrown 

 back to about the middle of the posterior third of the base of the 

 skull, and its plane is inclined from before upwards at an angle of 5°. 

 There are no posterior condyloid/orarwina. The styloid process is re- 

 presented by a very small tuberosity. A considerable space inter- 

 venes between the foramen magnum and the bony palate, which it- 

 self equally exceeds the corresponding portion of the human skull. 

 The zygomatic arches are opposite to the middle third of the cranium 

 as seen from below, in which position also the contraction of the 

 skull between the zygomata offers a marked distinction from that of 

 Man, 



In the front view of the cranium, the threatening supraciliary ridges 

 almost hide the cephalic cavity from view; and the latter, instead of 

 forming a broad back-ground to the face, as in the young Chimpan- 

 zee, and still more in Man, is surpassed in breadth by the lateral 

 boundaries of the orbits and the zygomatic arches. The orbits are 

 seated higher than in the Orang, and are larger in proportion; but 

 their plane is more perpendicular, and they are wider apart. In 

 neither the Chimpanzee nor the Orang is there a supraorbitary 

 foramen, but its place is marked by a slight groove. The lachrymal 

 bones are entirely confined to the orbit. A character by which the 

 Chimpanzee approximates more closely than the Orang to the human 

 subject is found in the nasal bone, which projects in a slightly arched 

 form beyond the interorbital plane, and exhibits at its lower margin 

 a trace of its original separation into two lateral portions : it is an- 

 chylosed with the osfrontis and the suture obliterated. The malar 

 bones are largely developed, and two or three sma\\ foramina are 

 observable in the process on the outside of the orbit. The contour 

 of the upper jaw from the nasal aperture to the incisor teeth is almost 

 straight, while in the Orang it is rendered concave by the greater 

 development of the alveolar processes of the intermaxillary bones. 

 The obliteration of the sutures between these bones and the upper 

 maxillary takes place at a much earlier period in the Chimpanzee 

 than in the Orang ; although in the young animal, when the first 

 dentition is complete, traces of the original separation are still 

 visible. The situation o^ the foramina incisiva is always indicative 

 of the original extent of these bones, and in no Mammal do they 

 approximate so closely to the incisive teeth as in Man, The infra- 

 orbitary canal opens upon the face by a sxn^e foramen : Mr. Owen 

 has observed a second in one young specimen, but never more. In 

 the Orang there are usually three or more, as in many of the inferior 

 Simice. The lower jaw, like the upper, is characterized by its strength 

 and relative size. Its symphijsis recedes, but the depth at this part 

 is much less than in the Orang. The alveoli advance more nearly 

 to the level of the condyle, and consequently approximate propor- 

 tionally to the structure of the brute; the menVdl foramen is single. 



Mr. Owen next proceeds to notice the denial formula and the 



3 N 2 



