Life association of shell and operculum of Middle Ordovician gastropod Maclurites

The only two known life associations of the shell and operculum of Maclurites Le Sueur, 1818, are described for the first time. Maclurites cf. magnus Le Sueur, 1818, from the Middle Ordovician of Alaska demonstrates that the operculum fits slightly inside the aperture, and when closed, the operculum extends down below the base of the shell and may have acted as an anchor. The operculum of Maclurites bigsbyi (Hall, 1861), from the Middle Ordovician of Wisconsin, is illustrated for the first time and is confirmed to be distinct from Maclurina logani (Salter, 1859).