Today's specimen is Tropidoleptus carinatus from the Sellersburg limestone of Indiana. The Sellersburg limestone is middle Devonian in age (Givetian stage) and lies above the Jeffersonville formation. The fossils below are from two different individuals but show both valves of T. carinatus. I purchased these specimens from a seller on E-bay some years ago.
Brachial valve dorsal surface
Brachial valve ventral surface
View of the rear of the brachial valve with the attachment points for the brachioles shown
Pedicle valve dorsal surface
Pedicle valve ventral surface
Left side profile of pedicle valve
Posterior of pedicle valve
Anterior of pedicle valve
T. carinatus is very common in the middle to upper Devonian aged rocks of North America. Some of the best specimens I have found come from the Kashong shale member of the Moscow formation in New York. I have never found examples of the species with individual valves before though, so these are special specimens in my collection.
These specimens come from the Sellersburg Limestone located in Clark County, IN which is near Louisville, KY and is dated to the Devonian period (Givetian stage).