DEEP-ORANGE color, due to copious quantities of xanthophyll esters of the taraxanthin class (Fox, 1936), renders the adults of the garibaldi, Hypsypops rubicunda (Girard), perhaps the most conspicuously brilliant fish along the rocky shores of southern California and northern Baja California. The intensity of the pigmentation raises numerous problems, bionomic as well as biochemical. Our hearty thanks are extended to the following: The National Research Council Fellowship Board in the Natural Sciences, for the opportunity given one of us (H. K.) to spend the year of 1946-47 in residence at the Scripps Institution of Oceanography; the Rockefeller Foundation, for the support of the research program of one of us (D. L. F.) on the comparative biochemistry of marine biochromes, which program included later phases of this investigation; the Steinhart Aquarium of the California Academy of Sciences, for two specimens; Bayard H. McConnaughey and Arthur S. Lockley, for valuable assistance in several quantitative phases of the investigation; to Mr. Lockley, further, for permission to state briefly some results obtained by him in experiments on another species and for an examination of the gut contents of garibaldis; and to Jack Prodanovich and associated Bottom Scratchers of San Diego, for procuring needed specimens.