The term area 8a of Brodmann refers to an area located on the posterior "lip" of the middle frontal gyrus that was defined on the basis of cytoarchitecture in the guenon. In comparison with area 8 of Brodmann (guenon), area 8a showed more pronounced layers of large pyramidal cells (layer IIIb in the external pyramidal layer (III)) and of ganglion cells in the internal pyramidal layer (V); the internal granular layer (IV) was less pronounced. The internal structure of the area was illustrated in Brodmann-1905. It was not mentioned or illustrated in the map of Brodmann's areas in Brodmann-1909.