1. Marine Tubificidae from Cape Cod Bay, received from the Systematics Ecology Program's Biotic Census, were examined.
2. One new genus and five new species are described, Adelodrilus anisosetosus nov. gen., nov. Sp., Peloscolex intermedius, Limnodriloides medioporus, Phallodrilus obscurus and Phallodrilus coeloprostatus.
3. The genera Limnodrioides, Phallodrilus and Spiridion are reviewed.
4. Aktedrilus is made a junior synonym of Phallodrilus.
5. L. roseus Pierantoni, 1903 and L. pectinatus Pierantoni, 1903 are treated as species dubiae of Spiridion.