Polycladida

Polycladida, a family of flat, leaf-shaped worms, with much-branched intestines, belonging to the order Dendroccelida (q.v.) and the class Turbellaria. They are all marine, and of interest, as they are supposed to have possible affinities with the Jellyfish belonging to the class Ctenophora (q.v.). This view is based on the position of the auditory organ, and of some bands of cilia in some Polyciads. The structure of the excretory and nervous systems is, however, opposed to such a view.