cyclostomi

Century Dictionary and Cyclopedia

1. In Cuvier's system of classification, the second family of his second order, Chondropterygii branchiis fixis, with the mouth formed into a sucker, containing the lampreys and hags, or the cyclostomous, monorhine, or marsipobranchiate fishes: a synonym of Marsipobranchii.

GNU Webster's 1913

1. n. (Zoöl.) A glass of fishes having a suckerlike mouth, without jaws, as the lamprey; the Marsipobranchii.