New tubes are rapidly built by the worms. Eggs are deposited on the surface of the sand, at the mouth of the tube. They may be left in sea water for several hours before insemination. The egg measures 150 microns in diameter. It is practically spherical, and is very opaque because of the large amount of yellow yolk.
Cleavage is equal and spiral, and no polar lobes are formed.
Gastrulation is probably by epiboly. MEAD, A. D., 1894. Preliminary account of the cell lineage of Amphitrite and other annelids. MEAD, A. D., 1897. The early development of marine annelids.