Inventory of the Crustaceans collected in the basin of the Fonatine des Suisses at Dijon. The Copepoda are represented by 5 species: Macrocyclops albidits, Eucyclops serrulatus in two slightly different forms, Eucyclops serrulatus var. mihi, Acanthocyclops venustus, Acanthocyclops vernalis and Acanthocyclops robustus. The coexistence of these two last forms in this very tiny environment makes it probable that we have here to do with two distinct species. A determination key is given for the Genus Acanthocyclops. Amphipoda are represented by Niphargus virei and especially Niphargus kochianus kochianus of which more than 100 samples have been collected. Of this last small species some considerations regarding geography, the laying of eggs, sexual dimorphism and closely related species are also given.