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Digestion was studied in the marine archaeogastropod Haliotis rufescens, with emphasis on identification of absorptive regions in the gut. Extracellular enzymes were found i n the digestive fluid. Absorption in the digestive gland was demonstrated by autoradiography of tissue sections after feeding animals o n 14C-labeled algae. After absorption, food was retained apically in the absorptive cells of the digestive gland in an insoluble form. Possible mechanisms of uptake are discussed. It was shown chromatographically that small compounds derived from the food were present in both the crop fluid and blood early in digestion. Studies in vitro showed that the crop epithelium was permeable to small organic materials. Glucose and phenylalanine were found to have been taken up by the crop epithelium in considerable quantities; smaller amounts were passed through the epithelium, and would in life be transferred to the blood. The surface area of the food mass was seen to be increased in an intestinal sorting area at the beginning of the intestine. The intestinal epithelium was shown in vitro to be permeable to glucose. It is concluded that the large crop is an important region of absorption, and that digestion and absorption continue to occur as food passes along the intestine.

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Large Protista of unknown taxonomic affinities are described from 3 species of coleoid squids, and are reported from many other species of cephalopods. The white to yellow-orange, ovoid cyst-like parasites are partially embedded within small pockets on the surface of the gills, often in large numbers. Except for a holdfast region on one side of the large end, the surface of the parasite is elaborated into low triangular plates separated by grooves. The parasites are uninucleate; their cytoplasm bears lipid droplets and presumed paraglycogen granules. Trichocysts, present in a layer beneath the cytoplasmic surface, were found by transmission electron microscopy to be of the dinoflagellate type. Further studies are needed to clarify the taxonomic position of these protists.