ever be omnivorous, since a similar Pacific Coast species is known to stun prey with the violent snapping of a specialized claw, hence the name, “pistol shrimp." It is difficult to conceive how, living encased in a cylinder of highly enmeshed fllaments of algae, it could feed on anything larger than very small plankton, if that, in addition to the algae. The simi- larity of the specific activities found in the viscera of the shrimp and in the algae, as shown below, indicate the effect of food habit upon the radioactivity of the digestive tract. Rigili d/m/g wet Shrimp muscle viscera Algae Runit a/m/g wet ' 15,000 7,000 110,000 31,000 210,000 36,000 - 103 -