110 MAN AND THE LOWER ANIMALS n 



drawn so as to give the cerebral cavity the same length in each 

 case, thereby displaying the varying proportions of the facial 

 bones. The line b indicates the plane of the tentorium, which 

 separates the cerebrum from the cerebellum ; d, the axis of the 

 occipital outlet of the skull. The extent of cerebral cavity 

 behind c, which is a perpendicular erected on b at the point 

 where the tentorium is attached posteriorly, indicates the degree 

 to which the cerebrum overlaps the cerebellum the space 

 occupied by which is roughly indicated by the dark shading. 

 In comparing these diagrams, it must be recollected, that 

 figures on so small a scale as these simply exemplify the state- 

 ments in the text, the proof of which, is to be found in the 

 objects themselves. 



between the Gorilla and the Baboon is even greater 

 than it appears at first sight ; for the great facial 

 mass of the former is largely due to a downward 

 development of the jaws ; an essentially human 

 character, superadded upon that almost purely 

 forward, essentially brutal, development of the 

 same parts which characterises the Baboon, and 

 yet more remarkably distinguishes the Lemur. 



Similarly, the occipital foramen of Mycetes (Fig. 

 17), and still more of the Lemurs, is situated com- 

 pletely in the posterior face of the skull, or as 

 much further back than that of the Gorilla, as that 

 of the Gorilla is further back than that of Man ; 

 while, as if to render patent the futility of the 

 attempt to base any broad classificatory distinction 

 on such a character, the same group of Platyrhine, 

 or American monkeys, to which the Mycetes belongs, 

 contains the Chrysothrix, whose occipital foramen 

 is situated far more forward than in any other ape, 

 and nearly approaches the position it holds in 

 Man. 



