Comparative biochemical studies of numerous marine invertebrates and fishes have indicated that the majority of such species so far examined selectively assimilate and store xanthophyllic or allied oxygenated carotenoids rather than carotenes, when consuming food containing both types of pigment. In some forms there is complete exclusion of carotenes, e.g., in several fishes, in the sea mussel (Mytilus californianus), in at least three brittle stars, and in some color-variants of the anemone Metridium senile. Some asteroid echinoderms store carotenes, but in far lower concentrations than xanthophylls, while four species of echinoids appear to assimilate relatively greater quantities of carotenes (Fox, Updegraff and Novelli, 1944).