NERVOUS SYSTEM. VERTEBRATA. 423 



There can be no doubt that the parieto-occipital sulcus 

 of Man is represented not merely by the sulcus so named 

 in the last specimen and other Apes, but also by the second 

 element distinguished as " ramus parieto-occipitalis sulci 

 intraparietalis." 



The caudal extremity of the intraparietal sulcus ends 

 without bifurcating under cover of the occipital operculum, 

 but does not reach the bottom of the Simian sulcus. 



In the right hemisphere the collateral series is repre- 

 sented by two long deep sulci. Below the calcarine there 

 is the true collateral sulcus, the posterior end of which is 

 separated from the calcarine by a submerged gyrus. 

 Occupying a more lateral position there is a second longer 

 and deeper sulcus of the same series, which must now be 

 called the inferior (or third) temporal or the occipito- 

 temporal sulcus. Posteriorly this appears to join the very 

 long inferior occipital sulcus at about its mid-point, but 

 there is a narrow submerged gyrus between them. The 

 anterior end of the inferior occipital is separated from the 

 Simian sulcus by a partially submerged gyrus, and its 

 caudal end is prolonged far back on to the mesial surface 

 almost as far as the calcarine sulcus. 



On the left hemisphere the inferior occipital is a very 

 short sulcus, the mid-point of which is joined by a vertical 

 furrow to the mid-point of the occipito-temporal sulcus. 

 The posterior half of the latter therefore takes the place of 

 the posterior (mesial) prolongation of the inferior occipital 

 sulcus on the right side. 0. C. 1338 A e. 



D.632. The brain of a Gelada Baboon (Papio gelada), ( ? ). 

 This brain is much smaller than those of most Baboons, 

 and hence the surface is less complicated. 



There is a collateral sulcus like that of the last specimen, 

 but the inferior occipital sulcus is placed lower, and is 

 greatly prolonged to form a sulcus parallel to and almost 

 coextensive with the collateral. 0. 0. 1338 A g. 



D. 633. The brain of a Drill (Papio leucopliceus). 



This is a relatively small and simple brain, which exhibits 

 the characteristic features of the Baboon's brain particularly 



