The correct name of the cymothoid isopod genus Meinertia Stebbing, 1893, has been in doubt since Hale (1927) maintained that the type-species of Codonophilus Haswell, 1881, C. argus Haswell, was founded on an immature specimen of Meinertia imbricatus (Fabricius). Hale based his opinion on a comparison of Haswell's holotype of C. argus, Port Jackson, New South Wales, with advanced brood-pouch young of M. imbricata unspecified Australian waters. If Hale's opinion is accepted, Meinertia becomes a junior synonym of Codonophilus. Subsequent to Hale's (1927) paper, some zoologists adopted the use of Codonophilus (e.g., Nierstrasz, 1931; Monod, 1931, 1933; Shiino, 1951; Pillai, 1954; Hurley, 1961; Lanzing & O'Connor, 1975; Stephenson, 1976). Others con tinued to use Meinertia (Balcells, 1953; Menzies, 1962; Szidat, 1966; Schultz, 1969; Roman, 1970; Geldiay & Kocatos, 1972; Trilles, 1972). Trilles (1972) argues that it has not been demonstrated that generic characters in the Cymothoidae can be found in juveniles of the Pullus secundus stage and that identification of juveniles not associated with adults is always extremely difficult. An examination of the nomenclatural history reveals that the Meinertia-Co donophilus question need not be at issue, since the valid name for the genus is Ceratothoa Dana, 1852, a name now in use for a different genus of cymothoids parasitizing flying fishes. Since priority requires changing the names currently used for 2 well known genera of Cymothoidae, the details of the nomenclatural history are given below. 1. Ceratothoa was proposed by Dana (1852), not Dana (1853) as usually cited. By the following footnote Dana (1852) included 2 species in Ceratothoa: uCymothoa Gaudichaudii et C. parallela hie pertinent. If a type-species were to be selected for Ceratothoa, it would have to be one of these species, now known as Meinertia gaudichaudii (Milne Edwards, 1840) and Meinertia parallela (Otto, 1828). 2. In his U.S. Exploring Expedition Report, Dana (1853) described 2 new species of Ceratothoa, C. linearis, until now considered to be a synonym of C. impressa (Say, 1818), from a fish in the Gulf Stream, and C. crassa, from the Southwestern Pacific. Both species are parasites of flying fishes and are now considered to be generically distinct the 2 species Dana (1852) originally included in Ceratothoa.