i06 THE ANATOMY OF VERTEBRATED ANIMALS. 



The frontals meet in the base of the skull over the ethmo- 

 prespheuoidal suture in the Gibbons and in the Grorilla, as in 

 the Baboons ; but not in the Chimpanzee or the Orang. The 

 alisphenoids unite suturally with the parietals, as is the rule 

 in Man, in the Gibbons and (usually) in the Orangs ; but, in 

 the Chimpanzee, the squamosal unites with the frontal and 

 separates the alisphenoid from the parietal, as happens, excep- 

 tionally, in Man. The nasal bones are flat and early anohylosed 

 together, in the Gibbons, Orangs, and Chimpanzees. In the 

 Gorilla the nasal bones are distinctly convex from side to side, 

 and rise above the level of the face. None of these Apes have a 

 spina nasalis anterior ; and, only in the Siamang, is there a 

 rudiment of the mental prominence in the mandible. The 

 premaxillo-maxillary suture persists beyond the completion of 

 the second dentition in all but the Chimpanzee, in which it 

 disappears before that period. The epiotic region is never 

 developed into a distinct mastoid process ; and there is an os- 

 sified styloid process only occasionally in the Orangs. The 

 palate is long and narrow, the alveolar margins being nearly 

 parallel, or even diverging anteriorly. The zygomatic arches 

 are strong, wide, and curved in two directions. 



The proportion of the length of the basi-cranial axis to 

 that of the cerebral cavity does not fall lower than the ratio 

 of 10 to 17 in any of the Anthropomorpha. 



The body of the hyoid approaches the form of that of Man 

 most nearly in the Orang. In the other genera it is more ex- 

 cavated posteriorly. 



The scapula of the Orang is most like that of Man, espe- 

 cially in the proportion of the supra- and infra-spinous fossas, 

 in the proportional length of the anterior and the posterior 

 borders, and in the angle made by the spine with the verte- 

 bral margin. In the other genera the posterior border is 

 longer in proportion than in Man, and the spine of the scapula 

 cuts the vertebral margin more obliquely. After the Orang's, 

 the scapula of the Gorilla comes nearest to that of Man. 



On the other hand, the long and straight clavicle of the 

 Orang is least like that of Man. 



The head of the humerus loses the backward inclination 

 which it has in the lower Apes, and becomes directed up- 

 ward and inward, as in Man. The radius and ulna are curved, 

 and leave a wide interosseous space. There are nine bones 

 in the carpus in both Hylobates and Pithecus, but only eight 

 in the Chimpanzee and Gorilla. In Hylobates the articular 

 surface presented by the trapezium for the pollex is almost 



