Abstract
The form of the egg, the structure of the oncomiracidium and the subsequent development of Entobdella soleae, a monogenean skin parasite of the common sole, are described. The reproductive organs develop in a constant sequence and the parasite is protandrous. Glands of Goto were observed in post-oncomiracidia of all ages.The early embryo of E. soleae possesses eight pairs of marginal hooklets and two pairs of hamuli. One pair of hooklets, centrally situated on the adhesive organ, undergoes metamorphosis and becomes the pair of accessory sclerites associated with the hamuli in the adult.My thanks are due to Dr J. Llewellyn for continued advice and criticism. The work was conducted during the tenure of a Fishery Research Training Grant from the Development Commission.