of Polychaeta, [253];
dimorphism of, in Polychaeta, [269];
thoracic, of Sabelliformia, [306];
of Terebellidae, [327];
of Chlorhaemidae, [334];
of Myzostoma, [344];
of Oligochaeta, [356] f., [381] f., [400];
of Leeches, [399];
of Gephyrea—see Brown tubes;
of Phoronis, [456]