The tapeta lucida and the organization of the visual cells of the walleye and the sauger are studied. The reflecting material of the tapeta is demonstrated to be a reduced pteridine, 7, 8-dihydroxanthopterin, which occurs in the epithelial processes as densely packed anisometric granules about 0.5 μm long.The organization of the visual cells and the unusual structure of the cones are suggestive of the manner in which incoming light is distributed in the retina. In dark-adapted eyes, the cods are in groups optically isolated from each other by the tapetal processes. Light can be reflected back and forth between the tapetal processes with additional absorption by the rods after each reflection. The cones do not move in response to changes of light intensity, remaining always at the external limiting membrane, and the light reaching the rods must first pass through the cones. The cone ellipsoids which contain lipid inclusions function as light funnels and increase the angle of acceptance of the rod groups. The melanosomes are stationary and concentrated at the tips of the pigment epithelial processes at the level of the cone ellipsoids. The disposition of the dark pigment indicates that it delimits the angle of acceptance of the cones.