Mysidacea (Crustacea) from dark submarine caves of the Northwestern Mediterranean sea and the neighbouring Atlantic (Portugal and Madeira). Studies on the Mysidacean fauna living in some dark submarine caves show that this biotop is princ1pally inhabited by important popuiations of the genus Hemimysis from the six species encontered in this work, three new species are descrlbed from the Atlantic caves: H. maderensis [Madeira), H. sophioe and H. spinifera (Portugal, Algrave coast), nn. ssp. Another new species
and new genus from the Heteromysini tribe, Hamelinella mariannae has been caught in the vicinity of Marseilles wlth mlcrotrapps. Hemimysis abyssicola Sars, 1869 repertoried by Bacescu (1941) from Viltefranche sur mer (Mediterranean sea) has not been collected. A posstble stemming from the North Atlantic species Hemimysis lamornae is proposed to the West mediterranean species.