The histology of the tube-feet and adjacent parts of the water-vascular canal of the crinoid Antedon bifida is described. The tube-feet possess the same basic structure as other, better-known tube-feet; here, however, they are adapted to collect food particles. They shoot out mucus by means of special muscle-operated glands and bend rapidly inwards to waft the mucus with entrapped particles into the food-grooves. The protraction of the tube-feet is probably brought about by a mechanism very similar to the ampulla system, of other extensile tube-feet, but here the contraction of restricted portions of the water-vascular canal provides the necessary hydrostatic pressure.

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