The term area 1-2 of Roberts refers to a subdivision of the cerebral cortex of the monkey (Macaca mulatta] based on cytoarchitecture. It consists of those parts of area 1 of Brodmann (guenon) and area 2 of Brodmann (guenon) located in the precentral gyrus ventral to the termination of the central sulcus. The cortex there is difficult to identify with either area 1 or area 2 exclusively, but "it is easy to recognize its similarity to both" ( Roberts-1963 ). The external granular layer 2 and internal granular layer 4 contain a rich population of granular cells; the external pyramidal layer 3 and internal pyramidal layer 5 are narrow and lack large pyramidal cells; the cells in layer 3 show a size gradient from small to medium as one proceeds from more superficial to deeper levels. The boundary of the multiform layer 6 with the subcortical white is distinct ( Roberts-1963 ).