Retinal Structure. Mollusc Cephalopods: Octopus, Sepia

*Research aided by grant (G-199) and summer Travel Fellowship (1957) from the National Council to Combat Blindness, Inc., and in part from the United States Public Health Service, Institute of Neurological Diseases and Blindness (B-397). Received for publ~catlon, July 7, 1958. chemical study of photoreceptors in our laboratory (1-5). The invertebrate photoreceptors have recently been reviewed by the Milnes (6). The visual structures in this phylum range from the so called simple light-detecting cells, eyespots, to complex eyes capable of forming a visual image.. The Octopus and Sepia eyes are single lens eyes provided with a mechanism for accommodation and resembling, in these respects and in their general