Ophiopluteus, [606], [608];

metamorphosis of, [613]

Ophiopsila, [499]

Ophiopteron, [492], [500]

Ophiopyrgus, [493], [497]

Ophioscolex, mouth-frame, [492]

Ophioteresis, [481], [491], [494]

Ophiothrix, [493], [499];

mouth-frame, [492];

O. fragilis (pentaphyllum), [478], [479];