Opinions from J. Leidy 1860
- 'Arctodus belongs to Carnivora'
- 'Arctodus pristinus belongs to Arctodus'
- 'Bison belongs to Ruminantia'
- 'Bos belongs to Ruminantia'
- 'Bos latifrons is recombined as Bison latifrons'
- 'Bos taurus belongs to Bos'
- 'Canis belongs to Carnivora'
- 'Canis familiaris belongs to Canis'
- 'Capra ammon is recombined as Ovis ammon'
- 'Castor belongs to Rodentia'
- 'Castor canadensis belongs to Castor'
- 'Castor zibethicus is recombined as Fiber zibethicus'
- 'Castoroides belongs to Rodentia'
- 'Castoroides ohioensis belongs to Castoroides'
- 'Cervus belongs to Ruminantia'
- 'Crocodilus mississippiensis is recombined as Alligator mississippiensis'
- 'Dama virginiana is recombined as Cervus virginianus'
- 'Dicotyles belongs to Pachydermata'
- 'Dicotyles fossilis belongs to Dicotyles'
- 'Didelphis [misspelled as Didelphys] belongs to Marsupialia'
- 'Didelphis virginiana belongs to Didelphis'
- 'Elephas belongs to Pachydermata'
- 'Elephas americanus belongs to Elephas'
- 'Equus belongs to Solipedia'
- 'Equus complicatus belongs to Equus'
- 'Equus fraternus belongs to Equus'
- 'Eubradys antiquus is a subjective synonym of Mylodon harlani'
- 'Fiber belongs to Rodentia'
- 'Hipparion venustum is recombined as Hippotherium venustum'
- 'Hippotherium belongs to Solipedia'
- 'Hydrochoerus belongs to Rodentia'
- 'Ischyrhiza belongs to Squalidae'
- 'Ischyrhiza mira belongs to Ischyrhiza'
- 'Lepidosteus bison belongs to Lepidosteus' according to DeKay 1842
- 'Lepidosteus bison belongs to Lepidosteus'
- 'Lepisosteus [misspelled as Lepidosteus] belongs to Lepidosteidae'
- 'Lepus belongs to Rodentia'
- 'Lepus sylvaticus belongs to Lepus'
- 'Mammut ohioticum is recombined as Mastodon ohioticus'
- 'Mastodon belongs to Pachydermata'
- 'Megalonyx harlani is recombined as Mylodon harlani'
- 'Megatherium belongs to Edentata'
- 'Megatherium mirabile belongs to Megatherium'
- 'Mylodon belongs to Edentata'
- 'Oromys aesopi is recombined as Hydrochoerus aesopi'
- 'Ovis belongs to Ruminantia'
- 'Pastinaca belongs to Squalidae'
- 'Pastinaca hastata belongs to Pastinaca'
- 'Pastinaca hastata belongs to Pastinaca' according to DeKay 1842
- 'Physeter antiquus belongs to Physeter'
- 'Procyon belongs to Carnivora'
- 'Solipedia belongs to Mammalia'
- 'Sus belongs to Pachydermata'
- 'Sus scrofa belongs to Sus'
- 'Tapir americanus is recombined as Tapirus americanus'
- 'Tapirus belongs to Pachydermata'
- 'Tapirus americanus fossilis belongs to Tapirus americanus'
- 'Tapirus haysii belongs to Tapirus'
- 'Testudo belongs to Chelonia'
- 'Trichiurus belongs to Squalidae'
- 'Trichiurus lepturus belongs to Trichiurus' according to Linnaeus 1758
- 'Trichiurus lepturus belongs to Trichiurus'
- 'Ursus lotor is recombined as Procyon lotor'
- 'Xiphias belongs to Squalidae'
- 'Xiphias robustus belongs to Xiphias'