formed by in situ upright fasciculate colonial rugosecorals. Preliminary data indicate that dwellers of this coralboundstone include crinoids, brachiopods, foraminifers, ostra-codes, gastropods, bryozoans, calcareous algae, and solitaryrugose corals. This coral boundstone was located at shal-low SW platform margin during the early Bashkirian, and it grew and died as relative sea-level rose and fell respec-tively, evidenced from increasing micrites and sparry calcite inthe boundstone and its overlying limestone, respectively. Therefore, the Serpukhovian-middle Bashkirian has the poten-tial for reef development, and the discovery of reefs is to be made