Abstract: Fossils of three species of Equus are known in the Gulongshan Cave Site at Dalian, i.e. E. hemionus (the wild ass), E. przewalskyi sinensis (the small wild horse) and E. dalianensis (the large wild horse) Though the small wild horse is close to the living species E. przewalskyi in size of the body and metapodials, their upper and lower cheek teeth are smaller than those in the living species E. przewalskyi. These characters can distinguish the small wild horse from the living species E. przewalskyi. Therefore the small wild horse was tentatively named E. przewalskyi sinensis in 1990. We have recently observed the enamel structure of the cheek teeth of E. przewalskyi sinensis, E. dalianensis. E. hemionus, and the living species (E. przewalskyi caballus and E. hemionus) with Scanning Electron Microscope (SEM). This paper reports the result of a SEM study of the enamel structure of the equid forms mentioned above.

摘要： 大连晚更新世的马类共包括三个种类:野驴(Equus hemionus)、小型的普氏野马中国马亚种(E. prxewalskyi sinensis)、大型的大连马(E. dalianensis)。从它们颊齿的釉质层微观结构、釉柱大小及釉质层的厚度分析，晚更新世的野驴和现生的野驴是十分接近的，可以归于同一个种。大连马与现在的普氏野马也比较接近，可归于同一个大的类别。然而，普氏野马中国马亚种却与现生的普氏野马有着比较显著的区别:中国马颊齿釉质层的釉柱平均直径比现生的普氏野马大得多，而釉质层的厚度又比现生的普氏野