118 THE RELATIONS OF MAN 



in the recent state, is interposed between the cerebrum 

 and the cerebellum, and prevents the former from pressing 

 upon the latter (see Fig. IT). 



This groove, therefore, indicates the line of separation 

 between that part of the cranial cavity which contains the 

 cerebrum, and that which contains the cerebellnm ; and 

 as the brain exactly fills the cavity of the skull, it is ob- 

 vious that the relations of these two parts of the cranial 

 cavity at once informs ns of the relations of their contents. 

 Now in man, in all the old world, and in all the new 

 world Simioe, with one exception, when the face is directed 

 forwards, this line of attachment of the tentorium, or im- 

 pression for the lateral sinus, as it is technically called, is 

 nearly horizontal, and the cerebral chamber invariably 

 overlaps or projects behind the cerebellar chamber. In 

 the Howler Monkey or Mycetes (see Fig. 17), the line 

 passes obliquely upwards and backwards, and the cerebral 

 overlap is almost nil ; while in the Lemurs, as in the 

 lower mammals, the line is much more inclined in the 

 same direction, and the cerebellar chamber projects con- 

 siderably beyond the cerebral. 



When the gravest errors respecting points so easily 

 settled as this question respecting the posterior lobes, can 

 be authoritatively propounded, it is no wonder that mat- 

 ters of observation, of no very complex character, but still 

 requiring a certain amount of care, should have fared 

 worse. Any one who cannot see the posterior lobe in an 



of the cast of a Chimpanzee's skull, which illustrates the paper by Mr. Mar- 

 shall ' On the Brain of the Chimpanzee ' in the Natural History Review for 

 July, 1861. The sharper definition of the lower edge of the cast of the 

 cerebral chamber in the Chimpanzee arises from the circumstance that the 

 tentorium remained in that skull and not in the Man's. The cast more accu- 

 rately represents the brain in the Chimpanzee than in Man ; and the great 

 backward projection of the posterior lobes of the cerebrum of the former, be- 

 yond the cerebellum, is conspicuous. 



