Abstract
The distribution and density of rods and cones have been determined in the temporal retina of the owl monkey Aotes trivirgatus. Rod density varied from 175,000/mm2 in the far periphery to 387,000/mm2 in the area centralis. Cone density was 4000/mm2 in the periphery and 7300/mm2 within the central retinal area. Variation of densities across the retina was continuous but the ratio of rods to cones remained about 50:1 at all locations. The cones are not randomly scattered, but are separated by distances of about 10 μ in central retina and 13 μ in peripheral retina.