(coal-ace-ee-um) is a euglenid flagellate in which the cells are attached to the substrate b y means of a mucoid stalk. the euglenids are attached to the stalks by their anterior region. As in this species, the stalks may branch and form moderately large aggregates. The individual cells may break free from the stalks and swim away, at which time they are indistinguishable from members of the genus Euglena
. Phase contrast.