The male gonad and gonopore lie dorsal to the anterior end of the pharynx. There is no female gonoduct. The absence of a female gonoduct is correlated with a peculiar mode of copulation. Egg-formation and egg-deposition bring about a crisis in the life of the individual which is not necessarily fatal. Extensive dedifferentiation and phagocytosis are associated with the development of the egg. After the egg has been laid, a new "head" is developed. Development of male gonads, in this rhabdocœle, appears to be dependent upon extrinsic rather than intrinsic factors.