Ameel (1939) redescribed Histrionella pomatiopsidis Stimpson, 1865, an ophthalmo-xiphidiocercaria from Pomatiopsis lapidaria, as Cercaria pomatiopsidis. He called attention to the similarity of this species to cercariae belonging to the family Allocreadiidae. In fact, recent work indicates that this family should include only species with ophthalmo-xiphidiocercariae (Hopkins, 1934; Cable and Hunninen, 1942). The structure of cercariae of this type, especially the presence of a stylet and stylet glands, suggests that this family is related to the Plagiorchioidea. We might go even further and suggest the hypothesis that this group on account of the presence of eye-spots in the cercariae and their development in rediae is more primitive than the Plagiorchioidea, and may be close to the ancestral type from which the true plagiorchiids developed. This possibility made it of special interest to determine whether the germinal development in the daughter rediae of Cercaria pomatiopsidis showed any resemblance to that in the daughter sporocysts of the plagiorchiids.