Wikipedia
Umbetoceras
Umbetoceras is a genus belonging to the goniatitid superfamily Gastriocerataceae and family Homoceratidae from the Carboniferous of the Russian Federation and Uzbekistan.
The shell of Umbetoceras is involute in the adult, with an evolute early stage and moderately wide umbilucus. Sculpture consists of strong riblets on intermediate stages with tubercles present on umbilical shoulder. The suture has a wide double pronged ventral lobe with a median saddle that exceeds two thirds its height.