The term area 24 of Brodmann-1909 (guenon) refers to a cytoarchitecturally defined cortical area that includes portions of the cingulate gyrus and the frontal lobe in the guenon. According to Walker-1940, in the macaque the molecular layer of the cerebral cortex (I) is moderate in thickness; layer III is broad; layers V and VI are undifferentiated and narrow. The cells are of medium size, larger in the inner portion of layer III and outer portion of layer V, and irregularly dispersed. Walker regarded area 24 of the monkey as cytoarchitecturally homologous to the area 24 of Brodmann (human) and area 25 of Brodmann (human) .