中文摘要：

记述了采自内蒙古二连浩特、额尔登敖包、扎木敖包和豪斯布尔都等地上始新统的兔形类化石：Desmatolagus vetustus、Gobiolagus tolmachovi和Leporidae indet．。对前两种以前未知的部分作了补充描述。着重讨论了额尔登敖包地点的“下白层”的归属和时代，认为它属乌兰戈楚组，时代为晚始新世。

英文摘要：

During 1980 -90 ＇s, some fossil lagomorphs were collected from Late Eocene of Erenhot, Urtyn Obo （ = Erden Obo） and Haosiburdu Basin, Nei Mongol, by the teams of IVPP using screen washing technique. They are first discovered in these localities. The new discovery not only expanded the distribution of the lagomorphs in Asia, added new material of the lagomorphs and augmented the content of the faunas at the localities, but also played an important role in determining the ages of the fossiliferous beds in these localities. The undescribed specimen collected from Jhamo Obo by the Third Asiatic Expedition is also described here. 1 Systematics Lagomorpha Brandt, 1855 Ochotonidae Thomas, 1897 Desmatolagus Matthew ＆ Granger, 1923 Desmatolagus vetustus Burke, 1941 （ Fig. 1A - K; Table 1 ） Specimens 1P2 （IVPP V 14759. 1）, 1P3 （V 14759.2）, 4P4 （V 14759.3 -5, V 14760.1）, 13M1/2 （V 14759.6- 14, V 14760.2 -5）, 2M3 （V 14759.15 -16）, 2p3 （V 14759.17, V 14760.6）, lp4 （V 14760.7）, 7ml （V 14759.18 -23, V 14760.8）, 4m2 （V 14759.24-25, V 14760.9- 10）, and l m3 （V 14759.26）. Localities and horizons IVPP LOc. 1988001 （V 14759）, east to the Railway Station of Erenhot, upper Eocene Houldjing Formation; IVPP Loc. 1991004 （V 14760） , Urtyn Obo, Siziwang Qi, ＂Lower White＂ of upper Eocene Ulan Gochu Formation. Remarks All the described specimens are lower crowned. The P2 and P3 are trilobate in occlusal view. The central cusp is the highest, and extends anterolingually and joins with the metastyle. The crowns of P4 - M3 are slightly higher lingually. M3 is small and its highly reduced talon is only composed of one small cusp. p3 is trilobate in occlusal surface, with one shallow anterior lingual reentrant and a deep hypostriid. The middle cheek teeth （ p4, ml and m2） are brachydont, with a narrow entostriid nearly as high as the wide hypostriid in height. The enamel layer of the posterior wall of the trigonid is thick and has a spike project backwards at