1. Cineradiography has been applied to study the respiratory current in Myxine glutinosa L.
2. Our observations reveal that contractions in the wall of the oesophagus and other branchial muscles, as well as in the gills and gill ducts, actively assist the velum in the maintenance of the respiratory current.
3. A system of sphincters on the gill ducts has been described. These sphincters function as delicate filters removing particles from the water passing through the gills, and thus preventing smothering of the active respiratory area inside the gill bodies. The gill-duct sphincters take also active part in the directional propulsion of the respiratory current.
4. Additional information has been gained on the function of the velum. Thus the velar chamber is not rigid, but can reduce its dimensions by contraction. These contractions closely accompany the velar movements and probably support the backward propulsion of water. It is further suggested that the lateral velar move ments also represent an active stage in the propulsion of water.