1. The carotenoids of three species of spindle shell, Fusinus perplexus, F. perplexus ferrugineus and F. forceps were investigated from the comparative biochemical point of view. The carotenoid patterns in the muscle, gonad and hepatopancreas were strikingly similar in all three species. In muscle the total amounts of carotenoids were high, ranging from 2.7 to 10.6mg/100g tissue. Canthaxanthin, (3S)-phoenicoxanthin, 4,4'-dihydroxy-pirardixanthin (=4,4'-dihydroxy-5,6,5',6' tetrahydro-fl,fl-carotene) and fritschiellaxanthin are the principal carotenoids in the muscle of all three species. In the gonad and hepatopancreas, the total amounts of carotenoids ranged from 3.5 to 8.5, and from 2.0 to 7.8 mg/100 g tissue, respectively, fl-Carotene, i~ocryptoxanthin and echinenone are dominant in the gonad. On the other hand, fl-carotene and halocynthiaxanthin are the major carotenoids in the hepatopancreas in all three species.