17. All four sensory clubs were removed from one, cutting as high up as possible so as to remove the endodermal tract of nerve fibers of the peduncle. It pulsated afterwards apparently the same as if the stalks had been left intact. 18. A small piece surrounding a sensory club and including the _margin_ can contract by itself. The piece observed pulsated with quick pulsations and rhythmically but intermittently. After a fresh cutting away of such a piece, the portion of the _velarium_ attached was seen to contract rhythmically, while the rest of the _subumbrella_ was not so seen. The part of the subumbrella above the radial ganglion that was cut off did not contract by itself. The same portion of the velarium cut off did give contractions. 19. A sensory club with the surrounding region cut out pulsated rhythmically; when the club was cut from the end of its stalk pulsation stopped. This observation was repeated on another, and contractions were seen after the removal of the club. A piece of the _subumbrella_ wall from the same animal gave contractions now and then even after an hour. 20. The normal position of a sensory club seems to be with the concretion almost at the lowermost end; often with it certainly lowermost, but probably oftener with the perpendicular passing through the center of the attachment of the club to its peduncle and just by the inner edge of the concretion. The eyes point inwards. When the animal is on its side the concretions are always quite lowermost. When the animal was inverted the tendency was for the concretions to be lowermost. In this position the eyes may point in several directions. In one instance those of one club pointed rather outwards, while of two other clubs they pointed more in the plane of the body wall. (See also Experiments 24, 29.) _Nerve._--21. Cutting the nerve eight times, once on each side of each sensory club, produced no loss of coördination in pulsating. The animal was weakened, however, by the operation, which was made drastic to insure cutting the nerve; but it was still able to swim. This experiment was repeated four times. 22. That coördination was continued after the nerve was cut was proved beyond doubt by cutting from the edge up (eight times) so as to perfectly separate the sensory clubs and the pedalia. Pulsations continued synchronously in all four sides--not the slightest evidence that one side contracted out of time with the others. 23. The eight cuts were made as in the preceding experiment with no loss of coördination noted. When the cuts were carried up to the base of the stomach, however, coördination ceased. The four side pieces seemed to contract each in its own time. Only two sides could be observed at one time, and they at any rate did not contract synchronously. One side often gave two contractions while the other side rested or gave one.