404 THE EXTERNAL CONFIGURATION 



however, also needed in regard to this subject, and other 

 convolutions than those above named should be similarly 

 tested.* 



The Cerebellum and its Lobes. 



The Cerebellum or * little Brain,' in the erect posi- 

 tion of the body, is situated behind and above the * pons ' 

 and Medulla (fig. 132), and lies in a posterior hollow of the 

 skull beneath the Occipital Lobes, from which it is sepa- 

 rated merely by a membranous partition. This membrane, 

 named the ' tentoriurn,' is an internal horizontal prolonga- 

 tion from the ' dura mater ; ' the Occipital Lobes lie on it 

 above, while the upper surface of the Cerebellum is in 

 contact with it below. 



The relative weight of the Cerebellum as compared 

 with the Cerebrum has already been referred to, and also 

 the fact of the great and progressive development of the 

 ' lateral lobes ' of this organ in the Quadrumana, and 

 even more markedly in Man, as compared with that of the 

 ' middle lobe ' which in him becomes a relatively diminu- 

 tive structure. 



No detailed reference to the relative development of 

 the several parts of the Cerebellum will here be made, 

 though the names of these parts may be ascertained by 

 the reader who will carefully study figs. 149 and 150, and 

 the references thereto. The comparative study of the 

 parts of the Cerebellum has not, indeed, received that 

 amount of attention from workers generally which has 

 been bestowed upon the Cerebrum ; and even if it had 



* An increased number of ' intercellular processes ' and fine ' com- 

 missural fibres ' within the Grey Matter (making this matter ap- 

 proximate more in character to the denser ' white substance ') might 

 be causes of such slightly increased specific gravity. 



