Two new species belonging to the new genusRivillinaare described from two Ordovician sites in the Armorican Massif:R. schallreuterisp. nov. (the type species) at Les Tanneries in the Domfront syncline from the lower part of the Pissot Formation (mid-Arenigian), andR. henningsmoenisp. nov. at Laillé in the Martigné-Ferchaud synclinorium from the lower part of the Traveusot Formation (Llanvirnian). At present, the systematic position ofRivillinais uncertain. It could have affinities with the order Bradoriidasensu stricto; alternatively, it may belong to the family Circulinidae Netskaya 1966 (suborder Binodicopina Schallreuter 1972; Order Beyrichiocopida Pokorny 1953).