The fauna and sediments of the Aymestry Limestone were studied in 24 localities along the outcrop in parts of Herefordshire and Shropshire. The outcrop is divided into two areas, defined as the Main Outcrop, extending from Aymestrey in the south to View Edge in the north, and the Northeast Outcrop, extending from View Edge northeastwards to near Hungerford - trending parallel with Wenlock Edge. The faunas in the Limestone of the two areas are different and this difference may be explained either by diachronism of the Limestone into younger horizons eastwards, or by an original variable and/or migratory fauna in a synchronous lithofacies.