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N. W. INGALLS 



arrangement are shown in figures 1 and 2. From the condition 

 which is common to both the Lemur and the lower Platyrrhine 

 there is an easy transition both to Cebus and the Cercopithe- 

 cidae (figs. 3-7.). 



In the members of the latter family the same essential pattern is 

 found; in Cercopithecus, Macacus, Cynocephalus and Semno- 

 pithecus. The first form has been the subject of a very careful 

 cy to-architectural study by Brodmann ('04) and both Cercopithe- 



superioi- postcentral 



central 



nterparietal 



parietooccipital 



lunate 



lateral calcarine 



Sylvian 



inferior occipital 



superior temporal 



middle temporal 



Fig. 3 Left hemisphere of Cercopithecus ruber. The sulci unlabelled in the 

 following figures can be identified from this. The parieto-occipital is, in reality, 

 beneath the mesial extremity of the lunate; cf. Cynocephalus, figure 5. 



cus and Macacus by Mauss ('08) from the myelo-architectural 

 point of view, while Schuster, following much the same principle 

 as Brodmann, has investigated the conditions in Papio (Cyno- 

 cephalus) hamadryas. Of the New World Apes, Cebus presents 

 conditions very similar to those in Cercopithecus but with a 

 much wider range of variation. 



In most of the above mentioned forms the sulcus centralis is 

 usually a quite regularly curved, deep furrow but there is a ten- 

 dency to irregularity in Cynocephalus. 



