CEEEBEAL CONVOLUTIONS — " SALLY." 67 



bifurcation of the intraparictal. How are we to distinguish 

 between the two ? We can scarcely regard the subopercular 

 furrow of the chimpanzees (fig. 32) as anything but the Affen- 

 spalte. Therefore, why should we not apply the same name to 

 an apparently similar furrow in fig. 17? 



In fig. 31, again, we have an arrangement somewhat like 

 that in the human brain (fig. 18), viz. the ramus occipitalis 

 {p^.) gives off a post-arcal branch, which is distinct from the 

 (greater part of the) AflFenspalte. The figs. 17 and 18 repre- 

 sent two sides of a human brain, and figs. 31 and 33 the two 

 sides of a chimpanzee's. 



I do not pretend to decide the matter. It would be great 

 presumption on my part, with ray slight experience of human 

 cerebral topography, to express any decided opinion on a 

 matter on which such authorities as Eberstaller, Ecker, and 

 Cunningham are at variance. I merely wish to bring forward 

 other facts and arrangements of these fissures which appear to 

 me to have some bearing on the question. 



7. The Occipital Lobe. 



The occipital lobe itself is more furrowed in "Sally's" 

 brain than in the ordinary chimpanzee, and bears some resem- 

 blance to that of Miiller's brain. 



The old terms given by Gratiolet to the gyri in the neigh- 

 bourhood of the parieto-occipital fissure, and to which so much 

 importance was at first attached — the annectant gyri, or '^pHs 

 de passage" — are now gradually being discarded. Since 

 Holleston and Turner showed their presence in chimpanzee, 

 where they are usually concealed by the operculum, the dif- 

 ferential importance of them has gone; and the names, though 

 still sometimes employed, appear to be giving way to more 

 descriptive and systematic terms. 



The pli de passage superieur externe and pli occipital supe- 

 rieur are now called by one name, " gyrus occipitalis primus" 

 (Ecker), or ''arcus parieto-occipitalis" (Eberstaller). 



This arcus parieto-occipitalis is well seen on the right hemi- 

 sphere, where it curves firstly round the lateral extremity of 



