Abstract
Breeding and development have been studied in a number of sipunculans, includingGolfingia elongata(Keferstein),G. vulgaris(de Blainville),G. minuta(Keferstein),G. pugettensisFisher,Phascolosoma agassiziKeferstein,Phascolopsis gouldi(Pourtalès),Themiste pyroides(Chamberlin),Phascolion strombi(Montagu) andSipunculus nudusL. (see Åkesson, 1958, 1961; Gerould, 1903, 1904, 1906; Hatschek, 1884; Rice, 1967; Selenka, 1875). However, the annual cycle of gametogenesis has been investigated in very few sipunculans, notablyG. vulgaris(Gonse, 1956a, b, 1957a, b) andP. agassizi(Towle & Giese, 1966, 1967).