of Echiuroidea, [435], [437], [439], [441];
of Epithetosomatoidea, [445];
used as generative ducts, [418], [438];
absent in Priapuloidea, [430]
Bryozoa, [475]
Buccal region, in Polychaeta, [249], [250], [269];
of Nereis diversicolor, [248];
of N. cultrifera, [316]
Buchanan, on marine muds, [423]
Buchholzia, [359]