cyclostome

Etymology

French cyclostome, from Ancient Greek κύκλος (kúklos, “circle”) + στόμα (stóma, “mouth”).

noun

1. Any of various primitive jawless fish of the class Cyclostomata, such as the lamprey or hagfish.
   Except the cyclostomes, as the lampreys and sphagobranchiæ, which are not real fishes, as I shall show elsewhere. 1811, André Marie Constant Duméril, “On the Sense of Smell in Fishes”, in Journal of Natural Philosophy, Chemistry, and the Arts, volume 29, page 344
   The Cyclostomes, or suckers, with regard to their skeletons, are the most imperfect of all the Vertebrates, 1835, William Kirby, On the Power Wisdom and Goodness of God, volume 2, William Pickering, page 390