The morphology of the gametes of four species of nummulitids is compared. Heterostegina depressa, Cycloclypeus carpenteri and Operculina cf. complanata have biflagellated gametes as most foraminifera. Nummulites venosus has triflagellated gametes which previously has been documented only in gamontogamous species. In addition, gamete flagella of Operculina cf. complanata have mastigonemes, a feature previously reported in only two foraminifera: the “lower” allogromiid Boderia turneri and the “higher” amphisteginid Amphistegina gibbosa.