AbstractRecent brings by the National Coal Board/Opencast Executive in the Mostyn Area have shown the presence of the Grrctrioceras listen' Marine Band some 90 feet above the Garrrioceru subcrenatm Marine Band. Faunal assemblages from these horizons are here lisred and a sketch map (Fig. 1) of the area is presented.The sigdicance of the record is noted and an earlier record of G. lisrm' near Connah's Quay referred to.