‖n. pl. [ NL. See Rhachis, and Glossa. ] (Zool.) A division of marine gastropods having a retractile proboscis and three longitudinal rows of teeth on the radula. It includes many of the large ornamental shells, as the miters, murices, olives, purpuras, volutes, and whelks. See Illust. in the Appendix. [ 1913 Webster ]