rhizostomata

‖n. pl. [ NL., fr. Gr. &unr_;&unr_;&unr_; a root + &unr_;&unr_;&unr_;, &unr_;&unr_;&unr_;&unr_;, a mouth. ] (Zool.) A suborder of Medusae which includes very large species without marginal tentacles, but having large mouth lobes closely united at the edges. See Illust. in Appendix. [ 1913 Webster ]