Trachydomia nodosa (Meek & Worthen, 1861) Showy gastropod with prominent nodes Middle Pennsylvanian Series - Desmoinesian Stage Marmaton Group - Altamont Formation Lake Neosho Shale Member - St. Louis, Missouri The abundance is considered common, however, large adult specimens are rarely found. This species is illustrated in Knight (1933) and is listed in Yochelson (1967). There is a partly developed shoulder on the upper part of the whorl that does not have nodes on th