Webster’s Revised Unabridged Dictionary · 1913
Gyracanthus
Gyr′a·can′thus (jĭr′ȧ·kăn′thŭs), n. [NL., fr. Gr. γυρός round + ἄκανθα spine.] (Paleon.) A genus of fossil fishes, found in Devonian and carboniferous strata; — so named from their round, sculptured spines.