The term area 24 of Walker refers to a subdivision of the cingulate gyrus in the macaque (Macaca) defined on the basis of cytoarchitecture. The first layer is of moderate width, the third layer is wide and the fifth and sixth layers are narrow and blended. The cells are irregularly arranged and of medium size, somewhat larger in the inner part of the third layer and outer part of the fifth layer than in other layers. Walker regarded the most likely cytoarchitectural homologue in the human to be the area 24 of Brodmann (human) ( Walker-1940 ).