The origin of the Antillean inland water fauna is discussed. It is assumed that the West Indian islands have been populated along three different lines: by dispersal, by divergence (fragmentation) and by stranding of marine elements during regression periods. – The phylogeny of the hadziid amphipods appears to correspond with the Regression Model. – The members of hadziid group are enumerated, the differences between the genera are tabulated and keyed. – The type-species of the genus Hadzia, H. fragilis, is re-examined. Hadzia taveresi is transferred to the new genus Metahadzia. – The genus Metaniphargus is re-surrected; its type-species M. curasavicus is re-described after topotypes and divided into two subspecies. Of M. nicholsoni, M. beattyi, and M. jamaicae descriptive notes, based on typical or topotypical material, are provided. Four new taxa of Metaniphargus are described from Aruba, Curaçao, St. Martin, Anguilla, and Puerto Rico. — A new genus, Saliweckelia, with two new species, is described from anchihaline localities in Curaçao and Bonaire.