PARIETAL REGION IN THE PRIMATE BRAIN 327 



tions energies and potentialities sufficient to entirely remodel 

 the whole lateral aspect of the hemisphere behind the central 

 fissure. Whether there are still resident in the brain of man, cor- 

 tical areas possessed of such prophetic and prodigious possibil- 

 ities is a question which we shall not attempt to answer. 



At this point we shall have to leave the chart of the Gibbon as 

 represented by Mauss and take up what we consider a more typi- 

 cal arrangement of fissures (figs. 8-10). Instead of pursuing 

 a comparatively straight upward and backward course toward 

 the parieto-occipital as it does in the lower apes, the superior 

 temporal sulcus very frequently bends upward and even distinctly 

 forward around the end of the Sylvian. There is thus left a large 

 area between it and the interparietal and lunate and it is here 

 that a very important fissure is found. In its new position the 

 upward end of the parallel sulcus does not represent the anterior 

 bounding sulcus of area 19 as it does in lower apes or may even in 

 certain Gibbon brains, but that anterior limit is indicated by 

 the above mentioned furrow which appears in the large area be- 

 hind the end of the parallel sulcus. This furrow is the sulcus 

 gyri angularis of Zuckerkandl ('04) and characterises his second- 

 ary gyrus angularis. It may be absent, particularly if the area 

 in which it occurs is small, or if present it may be independent or 

 form a (posterior) branch or even a continuation of the superior 

 temporal from which it is often separated by a submerged gyrus. 

 The interpretation of this sulcus is not quite clear. It might be 

 considered as representing the extremity of the superior temporal, 

 which, on account of the growth of the surrounding parts has be- 

 come, in certain cases, detached. On the other hand one might 

 look upon it as a new furrow, which owes its existence to the same 

 factors which have wrought so many changes in this region, 

 chief among which would be the new posterior end of the parallel 

 sulcus. This view would be further supported by the presence 

 of an annectant gyrus; the furrow would then be as pure an ex- 

 ample of compensation as one could desire. We are inclined to 

 believe that the difference in the two explanations is not so great 

 as it seems. This sulcus, which might have received a name less 

 apt to occasion confusion, is the anterior occipital sulcus of Wer- 



