Oar-feathers, [21]

Oates, on Sturinidae, [559]

Occiput, [20]

Oceanites, [60], [62], [65];

O. oceanicus, [65]

Oceanitinae, [59], [60], [65]

Oceanodroma, [61], [62], [67] f.;

O. cryptoleucura, [68];

O. furcata, [68];

O. hornbyi, [68];