Two new species of Normanellida are described from cold seeps at the southeast side of Hatsushima Island in Sagami Bay, Japan. A new genus Sagamiella is proposed to accommodate S. latirostrata sp. nov. and Normanella aberrans Bodin, 1968, originally described from 1200 m depth in the Bay of Biscay. The second cold seep species, N. bifida sp. nov., is placed in the genus Normanella and shows affinity to the species of the mucronata-lineage. The taxonomy of Normanella in NW Europe is thoroughly revised and several lineages are recognised within the genus. Both sexes of the problematic type species N. dubia Brady & Robertson in Brady (1880) are completely redescribed on the basis of material from the Isles of Scilly and Northumberland; a neotype has been designated. Material from Exmouth and Eddystone Lighthouse, identified by Norman & T. Scott (1906) as N. dubia, is redescribed as N. obscura sp. nov. The controversy over the antennule segmentation in N. minuta (Boeck, 1873) is reviewed and new diagnostic features for this species are illustrated. N. cf. minuta sensu Arlt (1983) from the Baltic is based on a copepodid V stage. The male from La Rochelle described as N. minuta (?) by Bodin (1972) does not belong to Boeck's species and is ranked species inquirenda in the genus. The presumed amphiatlantic distribution of N. minuta is based on unsubstantiated evidence. Willey's (1930) material from Bermuda does not belong to N. minuta and is considered species inquirenda in the minuta-lineage. N. minuta sensu Pallares (1975) from Argentina is regarded as a sibling species of the NW European species and renamed N. pallaresae sp. nov. The Norfolk material, originally identified as N. tenuifurca Sars, 1909, is described as a new species N. paratenuifurca which is closely related to the Norwegian one. The three illustrated records of N. serrata Por, 1959 refer to three different species. N. serrata sensu Bozic (1964) from La Reunion is considered species inquirenda in the minuta-lineage and Marinov & Apostolov's (1985) material from off the Spanish Sahara belongs to a different lineage which also includes N. sarsi sp. nov. from Norway. The intricate taxonomy of the mucronata-lineage is reviewed, resulting in the upgrade of N. mucronata reducta Noodt, 1955 to full species rank and the placement of Monard's (1928) N. mucronata var. quinquesetata as variety incertae sedis in the Normanellidae. The swimming leg sexual dimorphism in the family Normanellidae is re-evaluated and its phylogenetic significance re-assessed. The taxonomic concept of the family is restricted to include only the Normanellinae as defined by Huys & Willems (1989).