Abstract
Owing to the comparatively rare occurrence of most tectibranchs it is perhaps not surprising to find that, in spite of the ever-increasing knowledge of the histological structure and functioning of the alimentary canal of molluscs, little attention has been paid in this respect to these forms. The structure of the radula and gizzard has previously aroused interest, but so far as the rest of the alimentary canal is concerned most workers have been content with a somewhat superficial description of the gross morphology such as was given by Vayssière (1880), Bouvier (1893), Pelseneer (1893, 1894), and Guiart (1901). A more recent account of the digestive tract ofPhiline apertahas been given by Brown (1934), but this includes no histological or physiological consideration.