82 ANTHROPOID APES. 



gibbons, in which there are many specific variations 

 which our space will not allow us to consider in 

 detail, but a slight sketch of their organic system 

 must be given. The brain-pan of this animal's 

 skull is of an oval shape, without the crests so 

 characteristic of other anthropoids, and even in the 

 aged males of this species their development is so 

 slight as to be scarcely perceptible. The occipital 

 bone of male animals is, indeed, generally rounded, 

 and the whole occipital portion is somewhat com- 

 pressed in a downward direction, while the coronal 

 region is at the same time flattened. The cranium 

 gradually widens behind, so that, when seen from 

 above, its form is somewhat pear-shaped. In aged 

 males the orbits project from the low, retreating 

 frontal bone, and are surrounded by a bony, circular 

 rim. 



The face is not very prognathous, and the short 

 wide nasal-bones form a wide, depressed partition 

 between the orbits. The edges of the jaw-bones 

 describe a piu-abolic curve and are considerably 

 elongated. The palate is consequently long and 

 narrow. The rami of the lower jaw are wide and 

 low, and their coronoid processes are only slightly 

 developed. In aged males the teeth, and especially 

 the canine teeth, are long and projecting ; yet, com- 

 paratively speaking, they never attain to the great 

 development of those of other anthropoids. 



The number of vertebrae seems to be subject to 

 considerable variation even in the same species, and 

 various estimates are given by different naturalists. 

 MuUer, for example, has said that in several 



