Rousseauspira teicherti, a new genus and species of an unusual, untwisted, horn-shaped gastropod operculum from shallow-subtidal limestones of the Upper Ordovician of Alaska and the Middle Ordovician of California, is described and compared to two other Ordovician opercula,CeratopeaUlrich, 1911, andTeiichispiraYochelson and Jones, 1968. The shell to which the operculum belonged is not yet known.