SUMMARYThe occurrence of theConchocelis‐phase of a species ofPorphyrain the peduncular scales of the barnacle,Pollicipes cornucopiaat Roscoff, France, is recorded.ThisConchocelis‐growtb.closely resembles that described by Batters asG. rosea, the only species in the genus created by him. It is also identical with growths ofGonchocelisoriginating from spores ofPorphyra umbilicalis(L.) Kiitz. in culture.A study of the fertile cell rows occurring in the peduncular scales ofP. cornucopiasuggests that, by the breakdown of the transverse walls, tubes are formed and that the spores pass along these to the surface of the scales and are there liberated into the sea.The ecological importance of theGonchocelis‐phase in the life history ofPorphyrais str