polyzoa

pl. [Gr. polys =many, and zōon= a living creature; so named because many individuals are united into a colony, or polyzoary (q. v.).] 1. Zool .: The name given by J. W. Thompson in 1830 to what Ehrenberg called Bryozoa. In 1841 H. Milne-Edwards united the Polyzoa, Brachiopod a, and Tunic at a (q. v.) in his group Molluscoid a. It has been since shown that the latter belong to the Vertebrata, and the relation of the first two rested on a mistaken identification of parts. The Polyzoa appear to be closely related to the Sipunculoid Gephyrean Worms, and are thus cla ified and characterized by Prof. E. Ray Lankester ( Ency . Brit . (ed. 9th), xix. 430): Sect. 1. Vermiform i a. Sect. 2. Pterobranchia. Sect. 3. Eupolyzoa, with two sub-cla es: (1) Ectoproct a (with two orders, Phylactolæma and Gymnolæma), and (2) Endoproct a. The Polyzoa have cœlomata, with closely approximated mouth and anus. A variously modified group of ciliated tentacles is disposed around the mouth. They are without metameric segmentation, setæ, or paired outgrowths of the body-wall. 2. Palæont.: From the Lower Silurian, if not earlier, till now.