Abstract: A new species of galeaspid agnathan, Macrothyraspis longilanceus, is described from the Early Devonian Posongchong Formation ( Upper Pragian) at Zhichang village, Gumu Town, Wenshan District, southeastem Yunnan, China. As a typical non-marine deposit, the Posongchong Formation in southeastern Yunnan yields abundant remains of early vascular plants, antiarchs, sarcopterygians and galeaspids , the latter including Kwangnanaspis subtriangularis ( Cao, 1979) , Cantarostrataspis gengi, Cumuaspis rostrata ( Wang and Wang , 1992), Macrothyraspis longicornis (Pan, 1992) , Wenshanaspis zhichangensis and Sanqiaspis rostrata ( Zhao et al. , 2002) .

摘要： 记述了产于云南文山古木早泥盆世坡松冲组华南鱼类大窗鱼一新种——长矛大窗鱼(Mcrothyraspis longilanceus sp．nov．)。新种头甲呈头盔形，吻突与角均很发育，中背孔呈后缘前凹的桃形，头甲背面具一对蚕豆形的背窗，纹饰为细小的粒状瘤点，这些特征与属型种——长角大窗鱼(Macrothyraspis longicornis)相似。但新种吻突特别长，约为头甲中长的2倍，眶孔背位，两个背窗之间脑腔和迷走腔区域相对较宽，两个侧向延伸的角向后倾斜，末端不前翘等，与属型种区别明显，应为该属的一新种。