In line with my previous post regarding Protodouvillina, here are some examples from the upper Devonian of Iowa.
Interior of Pedicle valve
Here is a second specimen
Interior of the Pedicle valve
Four different specimens to show the variation within the species.
A Thank You goes out to my friend Nathan for giving me these specimens that he collected from the Cerro Gordo Member of the Lime Creek Formation (Fransian stage of the Devonian) near Rockford, Iowa.