Pipestoneia douglassi, a new genus and species of selenodont artiodactyl, is known from the middle Chadronian part of the Climbing Arrow Member of the Renova Formation exposed in the classic Pipestone Springs area along the extreme western margin of the Jefferson River Basin, Jefferson County, Montana. Specimens of P. douglassi are moderately common at the Pipestone Springs localities but have sometimes been mistaken for specimens of either “Leptotragulus” profectus or “Leptomeryx” mammifer, both of which are of about the same size and occur at the same localities. Although Pipestoneia is tentatively assigned to the Leptomerycidae, it exhibits some characters that make this assignment problematic, and the genus may well pertain to some other group of selenodont artiodactyls.