A considerable amount of yolk is present, rendering it heavy and opaque in the living condition. Two polar bodies are given off, and the first cleavage results in the formation of two unequal blastomeres. Gastrulation is probably by epiboly. An apical tuft forms within about eleven or twelve hours after insemination, and during the next 24 hours, elongated trochophores develop, which have a broad prototroch, a narrow telotroch, and red eyespots. These larvae continue to elongate, and by 60 hours have developed two or three sets of setae and a Y-shaped gut.
Swimming is by a rotating movement.
Report upon the Annelida Polychaeta of Beaufort, North Carolina. Reproductive organs of Diopatra. The breeding of animals at Woods Holl during the months of June , July and August. The marine annelids of North Carolina. Mar. Station, Bull.