REPRODUCTION AND LARVAL DEVELOPMENT OF PSEUDOPOLYDORA PAUCIBRANCHIATA (OKUDA) AND PSEUDOPOLYDORA KEMPI (SOUTHERN) (POLYCHAETA: SPIONIDAE).

1. The larval development of Pseudopolydora paucibranchiata (Okuda) and P. kempi (Southern) is described. Both species occur in tidal flats of California bays and estuaries. 2. Adult females of P. paucibranchiata deposit eggs in capsules which are attached to the inner lining of their tubes. All eggs are fertilized. Larvae develop in the capsules until they have 3 setigerous segments at which time they enter the plankton. After development of 13-17 setigers they begin to settle out of the plankton and assume a benthic life. 3. Eggs of P. kempi are also deposited in capsules, but in this case only a small percentage are fertilized. The unfertilized eggs fragment into separate yolk granules and are eaten by the developing embryos. After all yolk is devoured the larvae continue their development sustained by this stored food reserve. They remain in the capsule until they have about 15 setigers. They remain in the plankton only a short time before settling and taking up a benthic life.