AbstractSix Saimiri sciurea brains were studied. Coronal, horizontal, and sagittal sections were stained with cresyl violet. The frontal lobe map shows, anterior to the cental sulcus, a triangular area 4, agranularis giganto‐pyramidalis (FA). Anterior to area 4 is area 6, frontalis agranularis (FB), which differs from area 4 by the absence of Betz cells. Rostral to area 6 is area 8, frontalis intermedia (FC), a narrow, thick band of cortex, with a faint layer IV. Anterior to area 8 the cortex becomes thinner and more granular, its cells are smaller and this region is subdivided into area 9, frontalis granularis (FD), and area 10, fronto‐polaris (FE). Area 44 (FCBm) is on the inferior frontal gyrus, this cortex is granular limb of the arcuate sulcus is thin and granular, contains very large pyramidal cells in layers V and III: area 8a (FDT). The orbital cortex posteriorly shows an evident loss of layer IV; area 11 (FF). Area 50 is a narrow band of koniocortex in the inner wall of the fronto‐parietal operculum. On the gyrus rectus the cortex develops allocortical characteristics with a heavy layer V, area 12 (FG). The characteristics of limbic cortex (mesocortex) are present on the cingulate gyrus, area 24 (LA). Area 25 is found in the subcallosal r
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