of Cirratulus, [286];
of Nereis, [286], [316], [317];
of Arenicola, [333];
fossil, [302];
of Earthworms, [368];
of Sipunculus, [426]
Bursa seminalis, in Rhabdocoels, [48]
Busk, on Polyzoa, [465] n., [475], [487], [519]
Buskia, [533]
Bütschli, on Nematoda, [137]