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"Aflfenspalte" in the brain of a new-born child ^) and adds that he has 

 "seen the same condition present on one or two occasions in the 

 adult human brain". He states further that he is "therefore very far 

 from denying that the 'Affenspalte' is invariably absent in man". 

 My contention, however, is that if it is not invariably present, it 

 will at least be represented in some form in the vast majority of 

 human brains. For among several hundreds of Egyptian brains, which 

 I have examined, I have not been able to convince myself of its 

 certain absence in any case. It often happens that the sulcus 

 occipitalis superior becomes broken up and the caudal extremity of a 

 horizontally-placed sulcus lunatus (compare Fig. 5) is prolonged back- 

 ward to occupy the situation usually occupied by the former. 



Then again in a very considerable proportion of cases (not only 

 in Man but also in the Apes) a sulcus (Fig. 1 a), which I shall call 

 "praelunatus" runs forward from the sulcus lunatus toward the sulcus 

 temporalis superior, to which it often becomes joined. It often happens 

 that the sulcus praelunatus falls into line with the horizontal sulcus 

 lunatus so as to form a long furrow, which at first sight is puzzling 

 and difficult to explain. At other times the two sulci unite to form 

 a triradiate pattern. 



Fig. 6 represents one of those cases in which it is difficult to 

 decide whether the sulcus lunatus is really present. There are typical 

 sulci occipitales superior et inferior and no furrow between the former 

 and the caudal extremity of the apparent sulcus intraparietalis. The 

 relation of the latter furrow to the parieto- occipital sulcus seems to 

 open up the possibility that the furrow x is not the sulcus transversus, 

 as it seems to be, but a short deep sulcus lunatus joined to the 

 mesial limb of the sulcus transversus (which is placed further forward). 

 On the other hand the sulcus lunatus may have fused with the less 

 important sulcus occipitalis superior. This is one of those rare doubtful 

 cases concerning which it is not possible to speak dogmatically at 

 present. 



It is quite possible that further research may demonstrate that 

 the sulci lunatus and paramedialis may mark the external limits of the 

 definitely-modified retrocalcarine cortex concerned with visual pheno- 

 mena and that one may soon be able to speak more decisively as to 

 the identity of the lunate sulcus in these doubtful cases. 



1) The Surface Anatomy of the Cerebral Hemispheres, op. cit. p. 228, 

 Fig. 4i». The sulcus he labels "Affenspalte" (Ä.S.) is the sulcus occipi- 

 talis paramesialis (mihi) : the sulcus lunatus, however, is present also, 

 but is not labelled. 



