The upper Tremadocian graptolite-bearing stratum from the Nanba area ot Ylyang City, ttunan Provlnce is completely preserved, and Adelograptus is especially abundant. Based on the international data and our current study on the proximal development of this genus, it is very clear that there exists an apparent proximal development differentiation in the level of divergence of the first two thecae from the sieula. Therefore, the proximal development character is selected as the principle for the taxonomy of Adelograptus, and the current graptolite materials from the study area can be assigned into the two species of Adelograptus, named A. teneUus Linnarsson, 1871 and A. altus Williams, 1991.