[Geographical distribution of the cercariae parasites of the molluscs belonging to the genus Hydrobia in France (author's transl)].

The author lists forty eight different species of larval digenean trematodes, observed in 20,000 molluscs belonging to the genus Hydrobia (H. ulvae, H. acuta and H. ventrosa). These hosts were examined from twelve different salt marshes and estuaries around the coasts of France (seven on the Channel, three on the Atlantic Ocean and two on the Mediterranean sea). The collections were made in fifteen sites from 1973 to 1977. The list of the species of larval trematodes found in each site is shown in fifteen tables. These one sum up the prevalence of parasitism in each population of molluscs collected and at times its incidence over a period of two years or more.