Data on the detailed stratigraphic range of eight species of gastropod mollusks from the Upper Hauterivian of Ulyanovsk (Volga Region) are presented. A new genus, Trilemma, is established within the family Aporrhaidae. Two new species of this genus, T. russiense sp. nov. and T. striatocarinatum (Sinzow, 1880), are described.