The medusae fossil from the metamorphic rock of Mukeng Formation of Shangxi Group in the east segment of the "Jiangnan Old Land" is an important evidence to time the age of the host strata and disintegrate the host metamorphic stratigraphy. The medusae fossil is different from that of Edicara and Chengjiang fauna. Morphologically, it is similar to the Aurelia occurred in pelagic sea today, and it is termed as cf. Aurelia. It is possibly the later generation of the today′s Aurelia and must be generated in the time later than that of Chengjiang fauna. The occurrence of the cf. Aurelia indicates that the age of the host metamorphic rocks are probably in the range of Cambrian to Ordovician rather than that of Middle Proterozoic as previously suggested. Therefor, the metamorphic stratigraphy in the east segment of the "Jiangnan Old Land", at least the Mukeng Formation, was not the sediments of Proterozoic as previously regarded.
