The 21 lagomorph specimens collected in 1925 by the Central Asiatic Expedition from the late middle Eocene Shara Murun Formation at Ula Usu, Shara Murun Region of Inner Mongolia, are described. Among these specimens, two (AMNH 141275-6) are assigned to a new species, Gobiolagus burkei and the rest to G. tolmachovi. These specimens add to the Asian Eocene lagomorph diversity and to the morphology of known species.
Nine genera of lagomorphs are known from Asian Eocene beds, including Lushilagus, Shamolagus, Gobiolagus, Hypsimylus, Strenulagus, Dituberolagus, Valerilagus, Annalagus, and Desmatolagus. Most of the species are based on fragmentary specimens, and many original descriptions of these taxa are brief and poorly illustrated, which has caused difficulties and uncertainties in identification and taxonomy of the early lagomorphs in Asia. Thus, in addition to description of the new specimens from Ula Usu, we provide a brief review of the Eocene lagomorphs from Asia and comment on age issues for some of the localities. For some genera and species for which we have access to the type specimens, we provide emended diagnoses so that these species can be better characterized. Along with the diagnoses, we present photographs of the holotypes that are housed in the AMNH, in the hope that these images will help to identify and distinguish species of early lagomorphs in the future.