a genus of animals belonging to the order of vermes mollusca. The body is cylindrical, and fixed to a shell, rock, &c. It has two apertures; one on the summit, the other lower, forming a sheath. There are six species of this animal, viz. the papillosum, gelatinosum, intestinalis, quadridentata, rufica, and echinata; only one of which, viz. the rufica*, is found in the British seas. Animals of this genus have the faculty of squirting out the water they take in. The expansion and contraction of their bodies occasion their assuming various forms.