Comimrativc Osteology of the Oiang Utan and Chimpanzee* 463 



adult skull. That between the ala of the sphenoid bone and the 

 descending angle of the parietal, by means of which the frontal 

 and temporal are kept separate, and which offers one of the few 

 osteological differences in which the Orang has a closer approxima- 

 tion to the human structure than the Chimpanzeej is among those 

 which continue to be marked even in the adult. The occipitaiybra- 

 men approaches in figure, position, and aspect, nearer to that of 

 the lower Mammalia ; the occipital condyles are more closely ap- 

 proximated anteriorly; the anterior condyloid /orawm« are double 

 on each side; and the carotid /oramew is situated more posteriorly, 

 and is relatively smaller, than in the Chimjjanzee. The petrous 

 portion of the temporal bone is smaller, while the glenoid cavity 

 forms a much larger proportion of the base of the skull. This cavity, 

 if such it may be called, presents a quadrate, almost flattened sur- 

 face, slightly concave in the transverse, and slightly convex in the 

 antero-posterior direction, affording an interesting correspondence 

 with the structure of tlie molar teeth, and indicative of the vegetable 

 diet of the animal. The styloid and styliform processes are want- 

 ing, as in the Chimpanzee ; the mastoid is represented by a protube- 

 rant ridge, and its cellular structure is visible in consequence of the 

 thinness of the external table. The ant-auditory process is more 

 developed than in the Chimpanzee^ and the margins of the auditory 

 foramina are smoother. 



On the bony palate, the relative positions of \he foramina inci&iva 

 correspond with the increased development of the laniary teeth, and 

 consequently deviate in a proportionate degree from their positions 

 in the Chimpanzee and in the human subject. Two or three fora- 

 mina remain on either side and indicate the original separation of the 

 incisive bones ; and similar indications of the original harmonice 

 between the incisive and maxillary bones are seen on the anterior 

 part of the skull. In the Chimpanzee the obliteration of these sutures 

 takes place some time before the temporary teeth are shed ; in the 

 Orang they remain until the permanent teeth are almost fully deve- 

 loped : in the human subject the intermaxillary bones can be traced 

 as distinct elements only in the early periods of fcetal existence, when 

 they were first detected by the poet Goethe. In the Orang no part 

 of the OS nasi projects, as in the Chimpanzee^ beyond the plane of 

 the nasal processes of the superior maxillary bones ; and there are 

 no traces of its original separation at the mesial line, while in the 

 Chimjmnzee such traces are usually found, and Dr. Traill observed 

 two distinct ossa nasi in the young of that species dissected by him. 

 The lachrymal bones are proportionally larger than in Man ; but, as 

 in the Chimpanzee and the higher Quadrumanaf they are confined to 

 the orbit^ the whole outer boundary of which has a more anterior 

 aspect than in the Chimpanzee^ and is relatively broader and stronger, 

 but with the oblique posterior edge less developed. The interorbi- 

 tal space is relatively narrower, the disproportion increasing with 

 the development of the superior maxillary bones, and evidencing a 

 still further departure from the human form. There are three infra- 

 orbital /oramina instead of one ; the upper maxillary bones are much 



