Plecatrypa imbricata from the Silurian aged Wenlock formation (Wenlock epoch, Sheinwoodian to Homerian stage), near Dudley, England. The shell has a spirifer type shape with a wide hinge line and deep sulcus. It differs in that the pedicle valve does not have a triangular shaped opening for the pedicle muscle but rather a circular opening more typical of Rynchonellids. The shell also features strong, coarse ribbing and prominent growth lines. I have found this same genera in the Irondequoit Limestone of New York here.