PARIETAL REGION IN THE PRIMATE BRAIN 315 



Given two homologous neopallial areas, e.g., the area striata 

 in two forms, it would follow that their bounding sulci, called into 

 being by the increasing development of these very areas, would 

 be homologous and if the entire areas are homologous then the 

 entire extent of the sulcus of the one would be comparable to 

 the entire sulcus of the other, and while the sulcus may be inter- 

 rupted — gyrus translunatus — or disrupted, one should not institute 

 a comparison between the parts of one and the whole of the other. 

 If anyone is in doubt about the homology of the sulcus lunatus 

 let him compare Brodmann's ('06) figures 14, 26, 46 and 76 which 

 show unmistakably the relation of the striate area, operculum and 

 lunate sulcus in Homo, Simla satyrus, Semnopithecus and Cer- 

 copithecus. Many examples of the sulcus lunatus in man might 

 be culled from the literature (cf. Retzius, '96) where they have 

 often been passed unnoticed or have received other, frequently 

 inappropriate designations. It is natural to suppose that the 

 foldings of the cartex, the gyri and sulci, incident upon its con- 

 tinued development and increase in volume and area, should ex- 

 hibit some intimate relation to those areas, the development 

 of which, often very unequal in degree, has determined their 

 formation. 



But we are not reduced to the extremity of depending upon k 

 priori grounds. The extensive researches of Elliot Smith, Campbell 

 Brodmann, Mauss and others have placed this relation beyond 

 any reasonable doubt. Although the last two writers might dis- 

 claim any intention of putting such an interpretation upon their 

 findings we cannot do otherwise than look upon them in this light. 

 If there seems to be no exact and perfectly constant relation 

 between areas and surface markings, we have only to remember 

 that in very many cases the precise limits between different areas 

 have not yet been drawn. On the contrary, one cannot expect 

 that the thirty different areas mapped out by O. Vogt in his iso- 

 cortex parietalis, especially the numerous smaller areas in the 

 region of the central and postcentral sulci, will or can be all in 

 the same relation to sulci and gyri, for many of them, as compared 

 with the areas of Brodmann and Mauss, are quite small and it is 



THE JOURNAL OP COMPARATIVE NEUROLOGY, VOL. 24, NO. 3 



