The term area OC of Bonin refers to a subdivision of the occipital lobe of the macaque defined on the basis of cytoarchitecture. Identified with primary visual cortex, it "stretches widely over the lateral aspect of the occipital lobe almost to the lunate sulcus of the human anteriorly and to the inferior occipital sulcus ventrally. "On the medial surface it rapidly narrows as it passes forward and sinks into the depths of the calcarine fissure. It is the "most pronounced" granulous cortex and relatively thin ( Bonin-1947 ).