2. (Zo÷l.) (a) A soft tactile appendage of the mantle of many Mollusca, and of the parapodia of Annelida. Those near the head of annelids are Tentacular cirri; those of the last segment are caudal cirri. (b) The jointed, leglike organs of Cirripedia. See Annelida, and PolychŠta.
&fist; In some of the inferior animals the cirri aid in locomotion; in others they are used in feeding; in the Annelida they are mostly organs of touch. Some cirri are branchial in function.
3. (Zo÷l.) The external male organ of trematodes and some other worms, and of certain Mollusca.