Opinions from E. O. Ulrich et al. 1944
- 'Albertoceras belongs to Orthocerotidae'
- 'Albertoceras gracillimum belongs to Albertoceras'
- 'Albertoceras minimum belongs to Albertoceras'
- 'Albertoceras walcotti belongs to Albertoceras' according to Ulrich and Foerste 1936
- 'Avaoceras belongs to Bassleroceratidae'
- 'Avaoceras elongatum belongs to Avaoceras'
- 'Avaoceras longidomum belongs to Avaoceras'
- 'Avaoceras magnisiphonatum belongs to Avaoceras'
- 'Avaoceras wellsense belongs to Avaoceras'
- 'Baltoceras pusillum is recombined as Endoceras pusillum'
- 'Bassleroceras belongs to Bassleroceratidae'
- 'Bassleroceras alethes belongs to Bassleroceras' according to Billings 1865
- 'Bassleroceras bridgei belongs to Bassleroceras'
- 'Bassleroceras dalevillense belongs to Bassleroceras'
- 'Bassleroceras kayi belongs to Bassleroceras'
- 'Bassleroceras lasallense belongs to Bassleroceras'
- 'Bassleroceras spissiseptum belongs to Bassleroceras' according to Dwight 1884
- 'Bassleroceras tenuiculum belongs to Bassleroceras'
- 'Bassleroceratidae belongs to Cephalopoda'
- 'Buttsoceras belongs to Orthocerotidae'
- 'Buttsoceras odenvillense belongs to Buttsoceras'
- 'Buttsoceras vandiverense belongs to Buttsoceras'
- 'Cameroceras annuliferum is recombined as Endoceras annuliferum'
- 'Catoraphiceras belongs to Spyroceratidae'
- 'Catoraphiceras cushingi belongs to Catoraphiceras'
- 'Catoraphiceras lobatum belongs to Catoraphiceras' according to Ulrich and Foerste 1936
- 'Catoraphiceras osagense belongs to Catoraphiceras'
- 'Catoraphiceras resseri belongs to Catoraphiceras'
- 'Copiceras belongs to Orthocerotidae'
- 'Copiceras erectum belongs to Copiceras'
- 'Cyrtoceras acinacellum is recombined as Bassleroceras acinacellum'
- 'Cyrtoceras aristides belongs to Cyrtoceras' according to Billings 1865
- 'Cyrtoceras aristides is recombined as Endoceras aristides'
- 'Cyrtoceras beekmanense is recombined as Bassleroceras beekmanense'
- 'Cyrtoceras confertissimum is recombined as Onychoceras confertissimum' according to Whitfield 1886
- 'Cyrtoceras confertissimum is recombined as Onychoceras confertissimum' according to Ulrich and Foerste 1936
- 'Cyrtoceras dictys is recombined as Dyscritoceras dictys' according to Billings 1865
- 'Cyrtoceras kirbyi is recombined as Bassleroceras kirbyi'
- 'Cyrtoceras metellus is recombined as Dyscritoceras metellus' according to Ulrich and Foerste 1936
- 'Cyrtoceras metellus is recombined as Dyscritoceras metellus' according to Billings 1865
- 'Cyrtoceras microscopium is recombined as Bassleroceras microscopium'
- 'Cyrtoceras microscopium is recombined as Bassleroceras microscopium' according to Dwight 1884
- 'Cyrtoceras raei is recombined as Seelyoceras raei' according to Ulrich and Foerste 1936
- 'Cyrtoceras surgens is recombined as Onychoceras surgens'
- 'Cyrtoceras vassarina is recombined as Bassleroceras vassarina'
- 'Cyrtoceras winonicum is recombined as Ellesmeroceras winonicum' according to Stauffer and Thiel 1941
- 'Deltoceras tantillum is recombined as Stylocyrtoceras tantillum'
- 'Diaphoroceras avaense belongs to Diaphoroceras'
- 'Diaphoroceras belli belongs to Diaphoroceras'
- 'Diaphoroceras buffaloense belongs to Diaphoroceras'
- 'Dwightoceras belongs to Bassleroceratidae'
- 'Dwightoceras dactyloides belongs to Dwightoceras'
- 'Dyscritoceras belongs to Bassleroceratidae'
- 'Dyscritoceras oxfordense belongs to Dyscritoceras'
- 'Ectocycloceras belongs to Rudolfoceratidae'
- 'Ellesmeroceras belongs to Orthocerotidae'
- 'Ellesmeroceras bridgei belongs to Ellesmeroceras' according to Flower 1941
- 'Ellesmeroceras expansum belongs to Ellesmeroceras' according to Flower 1941
- 'Ellesmeroceras higdonense belongs to Ellesmeroceras'
- 'Ellesmeroceras hotchkissi belongs to Ellesmeroceras'
- 'Ellesmeroceras luthei belongs to Ellesmeroceras'
- 'Ellesmeroceras robsonensis is recombined as Robsonoceras robsonense'
- 'Ellesmeroceras thomasi belongs to Ellesmeroceras'
- 'Endoceras belongs to Endoceratidae'
- 'Endoceras baylorense belongs to Endoceras'
- 'Endoceras calvini belongs to Endoceras'
- 'Endoceras champlainense belongs to Endoceras'
- 'Endoceras knighti belongs to Endoceras'
- 'Endoceras lamottense belongs to Endoceras'
- 'Endoceras lawrencense belongs to Endoceras'
- 'Endoceras logani belongs to Endoceras'
- 'Endoceras monsensis belongs to Endoceras' according to Walcott 1924
- 'Endoceras monsensis is recombined as Walcottoceras monsense' according to Ulrich and Foerste 1936
- 'Endoceras philipsburgense belongs to Endoceras'
- 'Endoceras richardsoni belongs to Endoceras'
- 'Endoceras sansabaense belongs to Endoceras'
- 'Endoceras trundlesense belongs to Endoceras'
- 'Endoceras warthini belongs to Endoceras'
- 'Endoceras yellvillense belongs to Endoceras'
- 'Endoceratidae belongs to Cephalopoda'
- 'Endocycloceras belongs to Endocycloceratidae'
- 'Endocycloceras legorense belongs to Endocycloceras'
- 'Endocycloceras perannulatum belongs to Endocycloceras'
- 'Endocycloceras subcurvatum belongs to Endocycloceras'
- 'Endocycloceras wilsonae belongs to Endocycloceras'
- 'Endocycloceratidae belongs to Cephalopoda'
- 'Eothinoceras belongs to Eothinoceratidae'
- 'Eurystomites belongs to Tarphyceratidae'
- 'Kionoceras belongs to Orthocerotidae'
- 'Lawrenceoceras belongs to Bassleroceratidae'
- 'Leptocyrtoceras belongs to Bassleroceratidae'
- 'Leptocyrtoceras curvatum belongs to Leptocyrtoceras'
- 'Leptocyrtoceras powellense belongs to Leptocyrtoceras'
- 'Leptocyrtoceras virginianum belongs to Leptocyrtoceras'
- 'Maelonoceras metellus belongs to Maelonoceras' according to Billings 1865
- 'Monogonoceras belongs to Bassleroceratidae'
- 'Monogonoceras alabamense belongs to Monogonoceras'
- 'Monogonoceras magnisiphonatum belongs to Monogonoceras'
- 'Monogonoceras subrectum belongs to Monogonoceras'
- 'Ogygoceras belongs to Orthocerotidae'
- 'Ogygoceras gracile belongs to Ogygoceras'
- 'Onychoceras belongs to Bassleroceratidae'
- 'Onychoceras australe belongs to Onychoceras'
- 'Onychoceras subrotundum belongs to Onychoceras'
- 'Orthoceras adamsi is recombined as Buttsoceras adamsi' according to Butts 1926
- 'Orthoceras atticus is recombined as Oxfordoceras atticus' according to Billings 1865
- 'Orthoceras autolycus is recombined as Rudolfoceras autolycus' according to Billings 1862
- 'Orthoceras baculoides is recombined as Endoceras baculoides'
- 'Orthoceras cataline is recombined as Ectocycloceras cataline' according to Billings 1865
- 'Orthoceras cato is recombined as Ectocycloceras cato' according to Ulrich and Foerste 1936
- 'Orthoceras catulus is recombined as Protocycloceras catulus' according to Billings 1865
- 'Orthoceras colon is recombined as Catoraphiceras colon'
- 'Orthoceras cornuoryx is recombined as Rudolfoceras cornuoryx'
- 'Orthoceras cornuoryx is recombined as Orygoceras cornuoryx' according to Whitfield 1886
- 'Orthoceras deparcum belongs to Orthoceras' according to Billings 1859
- 'Orthoceras deparcum is recombined as Endoceras deparcum'
- 'Orthoceras durinum is recombined as Endoceras durinum'
- 'Orthoceras furtivum is recombined as Protocycloceras furtivum'
- 'Orthoceras glaucus belongs to Orthoceras' according to Billings 1865
- 'Orthoceras glaucus is recombined as Endoceras glaucus'
- 'Orthoceras hageri belongs to Orthoceras' according to Hall 1861
- 'Orthoceras hageri is recombined as Endoceras hageri'
- 'Orthoceras indigator belongs to Orthoceras' according to Billings 1865
- 'Orthoceras indigator is recombined as Endoceras indigator'
- 'Orthoceras laqueatum is recombined as Kionoceras laqueatum' according to Foerste 1921
- 'Orthoceras marcoui is recombined as Mysticoceras marcoui'
- 'Orthoceras marcoui belongs to Orthoceras' according to Barrande 1870
- 'Orthoceras marcoui is recombined as Endoceras marcoui' according to Barrande 1874
- 'Orthoceras montrealense is recombined as Clitendoceras montrealense'
- 'Orthoceras ordinatum is recombined as Protocycloceras ordinatum'
- 'Orthoceras perseus is recombined as Bassleroceras perseus'
- 'Orthoceras primigenium is recombined as Endoceras primigenium'
- 'Orthoceras sordidum is recombined as Catoraphiceras sordidum'
- 'Orthoceras spissiseptum belongs to Orthoceras' according to Dwight 1884
- 'Orthoceras tityrus belongs to Orthoceras' according to Billings 1865
- 'Orthoceras tityrus is recombined as Endoceras tityrus'
- 'Orthoceras xerxes is recombined as Protocycloceras xerxes'
- 'Orthocerotidae belongs to Cephalopoda'
- 'Orygoceras eburneolum belongs to Orygoceras' according to Stauffer 1937
- 'Orygoceras eburneolum is recombined as Endoceras eburneolum'
- 'Oxfordoceras belongs to Orthocerotidae'
- 'Oxfordoceras billingsi belongs to Oxfordoceras'
- 'Proterocameroceras belongs to Orthocerotidae'
- 'Protocycloceras belongs to Spyroceratidae'
- 'Protocycloceras abnorme belongs to Protocycloceras'
- 'Protocycloceras arkansasense belongs to Protocycloceras'
- 'Protocycloceras doniphonense belongs to Protocycloceras'
- 'Protocycloceras foerstei is recombined as Catoraphiceras foerstei' according to Butts 1926
- 'Protocycloceras levisense belongs to Protocycloceras'
- 'Protocycloceras manitouense belongs to Protocycloceras'
- 'Protocycloceras odenvillense belongs to Protocycloceras'
- 'Protocycloceras philipsburgense belongs to Protocycloceras'
- 'Protocycloceras smithvillense belongs to Protocycloceras'
- 'Robsonoceras manitouense belongs to Robsonoceras'
- 'Robsonoceratidae belongs to Cephalopoda'
- 'Rudolfoceras belongs to Rudolfoceratidae'
- 'Rudolfoceras kindlei belongs to Rudolfoceras'
- 'Rudolfoceras subarcuatum belongs to Rudolfoceras'
- 'Spyroceratidae belongs to Cephalopoda'
- 'Stemtonoceras belongs to Stemtonoceratidae'
- 'Stemtonoceras elongatum belongs to Stemtonoceras' according to Ulrich and Foerste 1936
- 'Stemtonoceratidae belongs to Cephalopoda'
- 'Stylocyrtoceras belongs to Bassleroceratidae'
- 'Stylocyrtoceras avaense belongs to Stylocyrtoceras'
- 'Walcottoceras belongs to Orthocerotidae'
- 'Walcottoceras obliquum belongs to Walcottoceras'
- 'Woosteroceras belongs to Stemtonoceratidae'
- 'Woosteroceras cherokeense belongs to Woosteroceras'
- 'Woosteroceras trempealeauense belongs to Woosteroceras'