Ortholophus, [390], [393]

Orthonyx, [503], [504]

Orthotomus, [514], [518]

Ortygornis, [226]

Ortyx, [202]-[204];

O. virginianus, [231], [232] f.

Ortyxelus, [293];

O. meiffreni, [187], [295]

Oscines, [466], [467], [494];

families of, [495] f.;