CEEEBRAL CONVOLUTIONS " SALLY." 61 



reality the prseparieto-occipital branch of the intra- parietal 

 fissure, which forms the anterior limit of the "■ arcus parieto- 

 occipitalis." This branch {n.), which Beddard's figure repre- 

 sents as joining the parieto-occipital, is separated by a gyrus 

 from this, but as it is overlapped by the superior parietal lobule, 

 its true relations are not seen in a view from above (as, for 

 example, in a photograph). 



After giving off this small branch the intra-parietal fissure 

 {p^.) curves slightly outwards and enters the Affeuspalte, the 

 well-marked obliquely-transverse groove so evidently the 

 remains of the more extensive fissure of the normal chimpanzee. 

 The hinder boundary of the Affenspalte on each side is a low 

 ridge only slightly above the level of the opposite side of the 

 furrow ; this is the remains of the operculum. 



In describing the terminations of the ramus occipitalis, 

 Cunningham states that the two forks into which it divides are 

 frequently almost at right angles to the main stem and nearly 

 in line with one another, giving rise to a transversely directed 

 fissure, which he identifies with the " occipitalis transversus " 

 of Ecker. 



The condition of afi'airs on "Sally's" left hemisphere (fig. 10) 

 is, indeed, not very unlike the left side of the figure of the human 

 brain given by Ecker, in which the fissure marked there o., into 

 which the intra-parietal falls, consists of two parts, one laterad 

 of the intra-parietal, which soon forks ; the other, mediad, lies 

 behind the parieto-occipital. The question arises, do these 

 two parts correspond to the two fissures in " Sally's" brain, the 

 laterad (Affenspalte) and the mediad {x.), which I have described 

 as a continuation of the ramus occipitalis ? In other words, 

 may the " occipitalis transversus " be composed of two parts 

 originally independent? This is a view held by Eberstaller. 



There is no doubt but that in the apes the bifurcation of the 

 intra-parietal is an independent thing which may or may not 

 become connected with the Affenspalte. In some cases the 

 outer, in other cases the inner fork enters the Affenspalte, or 

 both forks. Thus in Cunningham's figure, p. 203, right side, the 

 laterad fork is independent, the mediad joins the Simian fissure 



