Tank experiments with the terebratuloid Megerlina pisum indicate that food is obtained by filtration of sea-water drawn into the shell at the sides and exhaled anteriorly. Under laboratory conditions feeding periods of up to 12 hours were interspersed with resting periods of about equal duration. During the feeding periods the valves were maintained at full gape except for brief interruptions by complete or partial closures. Complete closures lasted several minutes whereas partial closures occurred about half as frequently and lasted only 1 or 2 seconds. Most of these closures did not involve the expulsion of faecal pellets. During the resting periods the valves remained closed for several hours at a time and this condition occasionally continued for 10 hours or more. Apparently a very low respiratory rate operates during these resting periods.