Spermiducal gland, [361]

Sphaerodoridae, [320]

Sphaerodorum, [321]

Sphaerosyllis, [308]

Sphaerularia, [150], [153], [160], [161]

Sphyranura, [73];

setae in, [56]

Spine, of Polyzoa, [481], [523] f., [524]

Spinther, [318]

Spio, [322]