genus of extinct gastropods (snails) preserved as common fossils in rocks of Devonian to Triassic age (416 million to 200 million years old) but especially characteristic of Late Carboniferous deposits (318 million to 299 million years old) in the midcontinent region of North America. Worthenia is characterized by a turban-shaped shell in which a raised ridge follows the margin of the whorls. Small nodes occur along the ridge, and the opening of the shell is oval and large.