Species Nemertes maculata Örsted, 1843(uncertain > nomen dubium, Included by Biirger (1904a: 128) among a group of dubious heteronemertean taxa.)
Species Nemertes maculosa Ehlers, 1871(uncertain > nomen dubium, Included by Bürger (1904a: 128) among a group of dubiously valid heteronemertean taxa.)
Species Nemertes microcephala Örsted, 1845(uncertain > nomen dubium, Uncertainly included in the genus Nemertes by Örsted, Bürger (1904a: 131) regarded it as only possibly being a nemertean.)
Species Nemertes microphthalma Örsted, 1845(uncertain > nomen dubium, Included by Bürger (1904a: 131) among a group of dubious species of nemerteans.)
Species Nemertes nigrofuscus Ehrenberg, 1831(uncertain > nomen dubium, Included by Bürger (1904a: 128) among a group of dubiously valid heteronemertean taxa.)