INTRODUCTION The district city Yuanmo of Yunnan is formerly known as Makai. It issituated approximately at latitude 25°36′N and longitude 102°E. The elevation ofthe Yuanmo basin is about 1,160 meters above sea-level, while the mountain rangesto the east and the west of the basin are generally above 2,000 meters. Thisbasin is drained by the Lungtsuanchiang which runs northward and joins the upper