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N. W. INGALLS 



deep curved sulcus, with a longer anterior ascending limb, the 

 so-called sulcus postcentralis inferior, and a shorter posterior de- 

 scending limb bent sharply around the upper end of the parallel 

 sulcus. This posterior limb is for the most part submerged in the 

 sulcus lunatus (Affenspalte) while the angle formed by the two 

 parts of the sulcus is separated from the fossa parieto-occipitalis 

 by the first annectant gyrus. One can, as will be seen later, dis- 

 tinguish a very short intermediate portion and these three por- 

 tions show considerable variation which in its turn depends on a 

 number of factors. In Cebus the anterior limb, known as the 



Fig. 4 Right hemisphere of same brain as figure 3. The arrow indicates an 

 annectant gyrus. 



inferior postcentral, is quite short and any indications of a 

 superior postcentral or a posterior subcentral are very faint or 

 entirely wanting. In Macacus and Cercopithecus both are often 

 present or both may be absent or only a superior postcentral is 

 present. Cynocephalus and Semnopithecus both possess as a rule 

 a superior postcentral and a posterior subcentral and the former 

 sulcus, particularly in Cynocephalus, may occasionally unite 

 with the interparietal. The lower end of the inferior postcentral 

 may either turn forward or be branched. At the same time the 

 inferior postcentral has not only approached the central sulcus 

 but has become more nearly parallel with it, and the angle formed 



