A unique subclass of ceramide oligosaccharides from whole tissue of the fresh-water bivalve Corbicula sandai has been isolated. Through the use of chemical, enzymatic, and physical techniques, two novel glycolipids were characterized as mannosyl-beta (1 leads to 4)-glucosyl ceramide and mannosyl-alpha (1 leads to 4)-mannosyl-beta (1 leads to 4)-glucosyl ceramide. 2. The components of fatty acids and long chain bases in the two glycolipids were analyzed by gas-liquid chromatography and were further identified by mass spectrometry. The data show that, with respect to the major components, both lipids have similar caramide moieties.