- An order of marsipobranchs including the lampreys. The suckerlike moth contains numerous teeth; the nasal opening is in the middle associated with the head above, nonetheless it cannot interact with the lips. See cyclostoma, and lamprey.
- A primary subdivision of myzonts, marsipo-branchiates, or Cyclostomata, including forms with all the roofing for the mouth or palate entire or imperforate, the single nasal duct maybe not penetrating it.
- lampreys as distinguished from hagfishes