Abstract
Guanine was the main component in extracts of argentea of redfish Sciaenops ocellata (Sciaenidae) and chorioids of sheepshead Archosargus probatocephalus (Sparidae). The argenteum of the redfish contained 1.55 mg guanine/cm2 surface area of chorioid. Hypoxanthine content was about 1/10 th that of guanine. The purines occurred as bisymmetrical hexagonal crystals ranging in shape from needles to platelets.