Cyclostomata

noun plural

Cy·​clo·​sto·​ma·​ta ˌsī-klō-ˈstō-mət-ə  ˌsik-lō- 

-ˈstäm-ət-ə

: a class or order of primitive vertebrates that have a large jawless sucking mouth, no limbs or paired fins, a wholly cartilaginous skeleton with persistent notochord, and 6 to 14 pairs of gill pouches and that include the lampreys and the hagfishes compare chondrichthyes