Orthoconic nautiloid Cephalopoda from the Carboniferous of west central Patagonia are described, including a new genus Sueroceras. Species described from the Carboniferous of Alaska, U.S.A., Ireland, U.S.S.R , Uruguay, and the Permian of Australia are included in the genus. Other specimens are doubtfully referred to Reti-cycloceras Gordon and Cycloceras M'Coy. Pseudorthoceras Girty is recorded for the firsi time from western Argentina. The goniatitid Glaphyrites Ruzhencev is also recorded. It is also noted that the goniatitid Tornoceras Hyatt seems to be restricted to the Middle Devonian of Argentina.