In November 1953, about one-half per cent of Lymnaea luteola taken from a pond in Alfred Park, Allahabad, were infected with an echinostome cercaria. The first collections of these cercariae were made by Dr Onkar Nath Srivastava, who was surveying cercarial infections in the snails and who kindly gave me the echinostome material. Additional material was obtained by numerous subsequent collections. After the cercaria was described it was possible to undertake a limited number of experiments in an attempt to discover other stages of the life cycle. It was found that Lymnaea luteola is both the first and the second intermediate host of a new species of Echninoparyphium. The adult of this new species, for which the name E. bagulai is proposed, matures in the intestine of the domestic duck, Anas poecilorhyncha. When this duck was experimentally infected with cercariae, the adult trematode was recovered from the intestine of this duck 21 days after its infection.