During a recent survey of Pacific psammophilous and phycophilous copepods an isolated female Bomolochus was found, the identification of which, in absence of its host, proved to be particularly troublesome. It became necessary to check the descriptions of all species of the genus Bomolochus Von Nordmann, 1832, and of several other genera of Bomolochidae, in the course of which I tried to find a satisfactory grouping of the many species described. This effort in so far proved to be disappointing that a fairly large number of species is so inadequately characterized that recognition, in absence of the host, is next to impossible. Taxonomy of parasitic copepods has, unfortunately, long been influenced by the obstinate notion that each host species should necessarily harbour its own parasitic species. This idea has overstressed the importance of the host, at the cost of information, particularly morphological information, concerning the parasitic animal, so that at present there is an overwhelming number of parasitic copepods of uncertain position, uncertain status or inadequate definition, impeding a much wanted natural grouping of the numerous species of parasitic Copepoda. The importance of complete structural information, especially for those species that are able to leave their host temporarily, cannot be too greatly stressed and it is gratifying to find such information in many of the modern publications (Stock, 1953, 1955; Shen, 1957; Shiino, 1957; Yamaguti, 1936, 1939, 1953, et al.). In the present paper I have presented, in condensed form, all available information on the Bomolochidae; I have suggested a subdivision of the genus Bomolochus, redescribed the female of Bomolochus bellones Burmeister and added the description of two new species. It is hoped that this paper will stimulate the redescription of doubtful or insufficiently described forms, preferably