Orthoceras nicolleti (FOSSIL) A.H. Clarke † Minnesota
Orthoceras niissoni (FOSSIL) Boll, 1857 †
Orthoceras novator (FOSSIL) Barrande, 1868 † Czech Republic, Bohemia
Striatocycloceras obliquum (FOSSIL) (d'Eichwald, 1860 †) Estonia, Harju, Nissi
Orthoceras oehlerti (FOSSIL) C. Gemmellaro, 1889 † Italy, Sicily, Palermo
Orthoceras orientale (FOSSIL) Fliegel, 1901 † Indonesia, Padang Highlands
Orthoceras oryx (FOSSIL) Whidborne † UK, Devon
Orthoceras oweni (FOSSIL) Ulrich, 1894 † Minnesota
Orthoceras pendens (FOSSIL) Blake † UK, Scotland
Orthoceras perroti (FOSSIL) A.H. Clarke † Minnesota
Orthoceras pertinens (FOSSIL) Blake † UK, Scotland
Orthoceras planoconvexum (FOSSIL) J.W. Hall † Minnesota
Orthoceras planodorsatum (FOSSIL) R.P. Whitfield † Minnesota
Orthoceras primaevum (FOSSIL) (Forbes) † UK, Wales
Orthoceras progressum (FOSSIL) Ruedemann, 1906 † USA, New York, Clinton
Trematoceras pulchellum (FOSSIL) (J. Von Hauer, 1849 †) Austria, Steiermark, Liezen
Orthoceras pulchrum (FOSSIL) Barrande, 1868 † Czech Republic, Bohemia
Orthoceras punjabiense (FOSSIL) L. Waagen, 1879 † Pakistan, Punjab, Sargodha
Orthoceras pusgillense (FOSSIL) Foord † UK, England, Westmorland
Orthoceras rachidium (FOSSIL) de Koninck, 1863 †
Orthoceras regularis (FOSSIL) (Schlotheim, 1820 †) Poland
Pseudospyroceras reticulum (FOSSIL) Kröger, 2008 † Morocco, Tafilalet
Tibichoanoceras riphaeum (FOSSIL) (P.A. Zhuravleva, 1978 †)
Orthoceras robertsii (FOSSIL) Whidborne † UK, Devon
Striatocycloceras romingeri (FOSSIL) (Foerste, 1932 †) Estonia, Ida-Viru
Trematoceras salinarium (FOSSIL) (J. Von Hauer, 1846 †) Austria, Oberösterreich, Gmunden
Trematoceras sandlingense (FOSSIL) (Mojsisovics, 1873 †) Austria, Oberösterreich, Gmunden
Orthoceras scabridum (FOSSIL) Angelin, 1880 † Poland
Ctenoceras schmidti (FOSSIL) Noetling, 1884 † Estonia
Tenuitheoceras secretum (FOSSIL) M.A. Frey & al., 2014 † Morocco, Tafilalet
Orthoceras sericatum (FOSSIL) Barrande, 1868 †
Orthoceras shastense (FOSSIL) A. Hyatt & Smith, 1905 † USA, California, Shasta
Orthoceras siculum (FOSSIL) C. Gemmellaro, 1889 † Italy, Sicily, Palermo
Orthoceras spissiseptum (FOSSIL) Dwight, 1884 † UK, England, Westmorland
Orthoceras stokesi (FOSSIL) Barrande, 1868 † Czech Republic, Bohemia