NERVOUS SYSTEM. VERTEBRATA. 393 



The cerebellum is very instructive. Its floccular lobe 

 still retains the form exhibited by most mammals. It 

 possesses a large projecting petrosal lobule of the parafloc- 

 culus. But these lobes appear to bo very small because 

 the rest of the cerebellum has attained such great 

 dimensions. 0. C. 1337 F. 



Flower, Proc. Zool. Soc. 1862, p. 328. 



D. 565. The brain of a Hairy Saki (Pithecia monachus). The left 

 hemisphere has been detached. 



The parieto-occipital sulcus extends further on to the 

 dorsal aspect and produces a corresponding bend in the 

 ramus occipitalis of the intraparietal sulcus. There is an 

 extensive sulcus behind and parallel to the transverse occi- 

 pital. It may represent the earliest phase of the Simian 

 sulcus the " Affenspalte " of German writers. 



Below this there is a small sulcus parallel to the tentorial 

 margin, which may represent the inferior occipital sulcus 

 of other Apes. 0. C. 1337 vd. 



D. 566. The brain of a Black Saki (Pithecia satanas). The left 

 hemisphere has been detached. 



This brain is much richer in sulci. The Sylvian fissure 

 is crossed obliquely at its upper end by the terminal portion 

 of the elongated parallel sulcus, with which (on the left 

 side) it is superficially continuous, though deeply it is found 

 that the two are separated by a submerged gyrus. The 

 intraparietal sulcus is acutely bent around the apex of the 

 parallel sulcus ; and from the angle of the former a deep 

 furrow extends on to the mesial surface. The upper end of 

 the parieto-occipital sulcus becomes swept, as it were, into 

 this intraparietal cleft, so that at a superficial glance the 

 two sulci appear to be concurrent. This furrow, which is 

 constituted by two separate elements, represents the parieto- 

 occipital sulcus of the highest Anthropoids. It consists of 

 a ventral element, which is clearly compensatory to the 

 calcarine", and a dorsal element (the " intraparietal cleft " 

 of this paragraph) . 



There is an extensive Simian sulcus. It runs rather more 

 than halfway across the hemisphere, and gives off a short 



