62 W. BLAXLAND BRNHAM. 



but again leaves it, whilst, as we see in " Sally " on the left side, 

 it is the laterad fork which enters the Affenspalte. Cunning- 

 ham shows that this is the case in the ape, and one of our 

 chimpanzees (fig. 31) somewhat resembles the left side of the 

 brain of Cebus albifrons figured by him in illustration of 

 the point (on p. 223 of his memoir). 



Amongst our specimens of chimpanzees it is very frequently 

 the case that the intra-parietal does not bifurcate, or if it does 

 the resulting figures are coextensive with Affenspalte. The 

 ramus occipitalis iu our specimens usually passes under the 

 operculum and enters the Affenspalte. In one case, however 

 (see figs. 22, 23), the parieto-occipital fissure makes so deep an 

 incision in the hemisphere that it cuts off the intra-parietal from 

 the Affenspalte. We have here a condition similar, as I believe, 

 to that described by Dr. Cunningham for Cebus capucinus, 

 which he uses to support his view as to the homology of the 

 " occipitalis transversus " with the bifurcation of the ramus 

 occipitalis. According to him the fissure regarded as ramus 

 occipitalis lies nearly at right angles to the rest of the intra- 

 parietal fissure, and the parieto-occipital fissure falls into the 

 system at this angle (loc. cit., fig. 45, p. 222). 



But it appears to me, from observations on C. robustus, 

 that another explanation may be given of the fissure he regards 

 as " ramus occipitalis," for in our specimen of this monkey, 

 if the occipital lobe be pressed backwards it is seen that the 

 parieto-occipital fissure is so deep that it extends more than 

 halfway across the hemisphere, and receives, nearly in its middle, 

 the intra-parietal. So that what in C. capucinus is regarded 

 by Cunningham as "ramus occipitalis" is in C. robustus 

 the outer part of the parieto-occipital. The Affenspalte, as 

 Cunningham shows, is quite independent of this transversely 

 placed fissure, as it is too, iu our chimpanzee (947/) just 

 referred to. 



Now in the human brain do we find any close similarity 

 between the arrangement of the convolutions iu this region 

 and those of ^' Sally " ? 



I have already referred to Ecker's diagram of a generalised 



