The term area 2 of Brodmann (guenon) refers to a subdivision of the postcentral gyrus of the guenon defined on the basis of cytoarchitecture. Brodmann-1909 regarded it as topologically and cytoarchitecturally homologous to area 2 of Brodmann (human). Distinctive features ( Brodmann-1905 ): compared to area 1 of Brodmann (guenon), the cortical thickness of area 2 is considerably less; the pyramidal cells of sublayer 3b of the external pyramidal layer (III) are larger and much more densely distributed which produces a more distinct difference between sublayers 3a and 3b; ganglion cells of the internal pyramidal layer (V) are on average much larger and more numerous and are not infrequently intermixed with cells the size of small giant pyramidal cells; layer V is also distinctly divided into a sublayer 5a and 5b where the latter is a clear strip between sublayer 5a and the multiform layer (VI); layer VI consists of a dense outer sublayer 6a of triangular cells and a sparser deeper sublayer 6b of fusiform cells. Authors von Bonin and Bailey disputed the existence of area 2 which they sought unsuccessfully to identify in the macaque as area PD of Bonin ( Bonin-1947 ).