Wikipedia
Ellinoceras
Ellinoceras is a small, straight, annulate actinoceratid from the Middle Ordovician of northeastern Siberia with strongly sinuous sutures and subcentral siphuncle. Sutures have 14 narrow lobes and saddles, the ventral lobe deep and broad with a small median saddle. The siphuncle segments are short and broad with short necks and a wide endosiphuncular tube.
Ellinoceras somewhat only superficially resembles other members of the Actinoceratidae and is distinct mainly by its sinuous sutures.