The term area 21 of Vogts refers to an area of the cerebral cortex of the guenon that is defined on the basis of cytoarchitecture and myeloarchitecture. The authors regarded it as topologically different from area 21 of Brodmann (guenon) and area 21 of Mauss on the basis that they found an area 19b of Vogts in a location that had been included in areas 21 of Brodmann and Mauss ( Vogts-1919 ).