The first appearance (FAD) of Clarkina postbitteri is not suitable to be used as the definition of the basal boundary of the Lopingian Series in the Penglaitan section, nor is the base of bed 6j suitable to be used as the GSSP of the Lopingian. The basal boundary of the Lopingian should be defined by the FAD of Clarkina duk-ouensis in the Clarkina postbitteri-C. dukouensis evolutionary lineage. The precise position of the FAD of C. dukouensis in the Penglaitan section is at the base of the LPD114. 6-6k (GSSP).