437 



presents a sulcus lunatus ("Affeiispalte"), an occipital operculum and 

 a Y-shaped sulcus occipitalis superior (s. i. l), which every impartial 

 observer must admit to correspond to the similar features ex- 

 hibited in the right cerebral hemisphere of the young Orang shown 

 in Figure 2. Nor can these be any doubt concerning the identity of 

 the occipital operculum and the neighbouring sulci in the left cerebral 

 hemisphere of another adult Egyptian and the right hemisphere of a 

 young Chimpanzee (Anthropopithecus troglodytes Schweinfurthi S juv. 

 from the Niam-niam country), which have been represented in juxta- 



s. intrapar. 

 inc. isar. occ. 



s. lunat. 



s. i. 1. (r. d.) 



s. 1. ro. 



s. temp. s. 



s. i. 1. '■"^ It %^ \ _^ \/ — s. temp. i. 



s. infrastr. oj)erc. occ. 



Fig. 2. The corresponding region in an Orang. s. i. I. sulcus occipitalis intra- 

 striatus lateralis (occ. superior), s. i. I. (r. d.) ramus dorsalis s. occ. i. 1. s. i. m. sulcus 

 occipitalis intrastriatus mesialis (retrocalcarinus , "calcarine fissure" of most writers). 

 Ä. infrastr. sulcus occii^italis infrastriatus (occ. inferior). 



position in Figure 3. And if we take individual examples of Gorilla- 

 brains it becomes still easier to match the occipital pattern of each 

 of them in numerous human brains. The grouping of the occipital 

 sulci represented in one of the Gorilla - brains described by Beddard 

 (Proc. Zool. Soc, 1899, Figure 7, p. 73) and the writer (Catalogue 

 of the Royal College of Surgeons' Museum, specimen number 660) is 

 particularly common in the brains of Egyptians and Soudanese. Al- 

 though the specimens represented in Figures 1 and 3 are by no means 

 exceptional, the resemblance to the Simian pattern of sulci is as a rule 

 not quite so obvious as it is in these cases: so that it is easy to 

 appreciate the difficulties which have beset investigators of European 

 types of brain and to understand the reasons for the common belief 

 in the absence of the supposed distinctively Simian sulci on the lateral 

 aspect of the occipital region of the human brain. In the series of 



