Wikipedia
Strophiceras
Strophiceras is an extinct cephalopod genus from the Order Nautilida, which includes, in a separate family, Nautilus and Allonautilus.
Strophioceras, a gyrogonic form that comes from the Middle Devonian of Europe and named by Hyatt in 1844 is part of the Trigonoceratacean family Centroceratidae which was extant from the Devonian to the Early Permian. ( 1954. Flower 1950)
For further description see Centroceratidae''