gill of, [329]

Pits, ciliated, of Polychaeta, [272], [273]

Placostegus, colour, [292];

from deep sea, [300]

Placunella, [73]

Plagiochaeta, [358], [381], [384]

Plagiostoma, [46];

British species, [50]

Plagiostomatidae, [50]

Planaria, [30], [31] f., [39];