The primitive type sperm of metazoans characteristically has a short round or conical head, a midpiece usually containing 4-5 mitochondria and a long flagellum (Franzen, 1956). The head usually contains the nucleus and an acrosome. The initiation of the fertilization process in many species occurs when the sperm first makes contact with the egg or egg coat and the acrosome undergoes well-defined changes in structure (for review see Colwin and Colwin, 1967; Franklin, 1970). These changes vary from species to species. Fine structural studies of coelenterate sperm are sparse, and the majority of these studies have been done on sperm of the hydrozoans (Szollosi, 1964; Burnett et al., 1966; Weissman et al., 1969; Hanisch, 1970; Hinsch and Clark, 1970; Stagni and Lucchi, 1970; Summers, 1970; Lunger, 1971). The only exception to the above is Afzelius and Franz#{233}n’s study of the primitive scyphozoan Nausitho#{235}. The above studies indicated that coelenterate sperm may lack an acrosorne. It is interesting, however, that while no discrete acrosome has been described numerous investigators (Hanisch, 1970; IIinsch and Clark, 1970; Summers, 1970; Afzelius and Franzen, 1971; Dewel and Clark, 1971; Lunger, 1971; O’Rand,