Robustum Nodum

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Robustum nodum is the one species of a problematic genus of Ordovician hemithecellid mollusc proposed by STINCHCOMB and DARROUGH in 1995. Hemithecella is a problematic genus of Ordovician mollusc proposed by Stinchcomb and Darrough in 1995. Hemithecella belongs to what are informally known as multiplated molluscs; it is found in the late Cambrian of the Ozarks and the Lower Ordovician of the same region as well as in Minnesota and the southern Appalachian Mountains. Hemithecella has muscle scars identical to a monoplacophoran and not the musculature of a chiton to which some authors have suggested the multiplated molluscs belong. It is therefore classified in the Mattheviidae.