The material treated in this paper was collected by the "Atlantide" and "Galathea" Expeditions in 1945-46 and 1950-52, respectively. It includes 105 species of polychaetes belonging to 13 of the so-called errant families. One species, Pontogenia augeneri, is new to science and 13 species are new to West Africa. In addition, the known distribution of many species is extended from Northwest Africa (Morocco) and South Africa to more central parts of the West African coasts.