With 2 Plates Ⅰ. INTRODUCTION Both Middle and Upper Carboniferous rocks are well developed in Western Kansu and were investigated by Loczy [19], Obrutchev [21],Yuan [31, 32], and Sun [25]. Though the faunas from these rocks have been studied in some detail by Loczy, Chao, Lee and others, their stratigraphic succession and the correlation of fossil horizons found in them in different localities yet remain to be established. In 1941-942, T. K. Huang and party, of which the writer was a member, made reconnaissance