Morphotropis helicina (FOSSIL) (Lindström, 1884 †)
Morphotropis monticola (FOSSIL) J. Perner, 1903 †
Morphotropis nitidissimum (FOSSIL) (Lindström, 1884 †)
Morphotropis obsolescens (FOSSIL) J. Perner, 1903 †
Morphotropis procera (FOSSIL) J. Perner, 1903 †
Morphotropis tremulans (FOSSIL) J. Perner, 1903 †
Omphalonema carbonaria (FOSSIL) (Yin, 1932 †)
Omphalonema globosum (FOSSIL) Horný, 1992 †
Oriomphalus multiornatus (FOSSIL) M.A. Frey & al., 2014 †
Oriomphalus puellarum (FOSSIL) Horný, 1992 †
Oriomphalus supralirata (FOSSIL) (Rohr & Smith, 1978 †)
Oriostoma actaeon (FOSSIL) (J. Perner, 1907 †)
Oriostoma acutum (FOSSIL) Lindström, 1884 †
Oriostoma angulatum (FOSSIL) (Wahlenberg, 1821 †)
Oriostoma approximans (FOSSIL) (J. Perner, 1903 †)
Oriostoma aspirans (FOSSIL) (J. Perner, 1903 †)
Oriostoma assidua (FOSSIL) (J. Perner, 1903 †)
Oriostoma barrandei (FOSSIL) E.C. Munier-Chalmas,1876 †
Oriostoma barroisi (FOSSIL) (Spitz, 1907 †)
Oriostoma chaleurensis (FOSSIL) Northrop, 1939 †
Oriostoma compar (FOSSIL) (J. Perner, 1903 †)
Oriostoma confertissima (FOSSIL) (J. Perner, 1903 †)
Oriostoma conjugata (FOSSIL) J. Perner, 1903 †
Oriostoma coralli (FOSSIL) (de Sowerby & Murchison,1839 †)
Oriostoma corniculum (FOSSIL) (J. Perner, 1907 †)
Oriostoma coronatum (FOSSIL) Lindström, 1884 †
Oriostoma costata (FOSSIL) J. Perner, 1903 †
Oriostoma delicata (FOSSIL) (J. Perner, 1903 †)
Oriostoma disjunctum (FOSSIL) Barrois, 1889 †
Oriostoma distans (FOSSIL) (Lindström, 1884 †)
Oriostoma dives (FOSSIL) (J. Perner, 1903 †)
Oriostoma dulcis (FOSSIL) J. Perner, 1903 †
Oriostoma echinatum (FOSSIL) Oehlert, 1877 †
Oriostoma gerbaulti (FOSSIL) Oehlert, 1877 †
Oriostoma giganteum (FOSSIL) (Lindström, 1884 †)
Oriostoma globosum (FOSSIL) (von Schlotheim, 1820 †)
Oriostoma hoyi (FOSSIL) (J.W. Hall, 1861 †)
Oriostoma incarinata (FOSSIL) Foerste, 1893 †
Oriostoma ingenua (FOSSIL) J. Perner, 1903 †
Oriostoma involuta (FOSSIL) Barrois, 1889 †
Oriostoma konincki (FOSSIL) Oehlert, 1877 †