Tofangoceras
Tofangoceras is a pseudorthoceroid cephalopod from the Middle Ordovician of the USA (NY) and Asia (S. Manchuria, Korea, and Siberia) belonging to the Stereoplasmoceratidae and similar to Stereoplansmoceras.
The shell of Tofangoceras is long, straight, and faintly annulated, less strongly than for Stereoplasmoceras. The siphuncle is central with moderately expanded, spindle-like segmeents. Aperture unknown.