Compiling an extensive array of information and literature, on the Caligidae, copepods predominantly parasitic on fishes, this book provides a comprehensive generic revision of the "sea lice" family Caligidae, as well as a phylogenetic analysis of this family and a discussion on the taxonomic status of the genera previously belonging to the Euryphoridae.

Chondracanthus zei Delaroche is redescribed based on the specimens recovered from Zeus faber L. collected at Sado Island in Sea of Japan. A general review of the genus is given accompanied with a key to and a cladistic analysis of the valid species. Thirty-seven species are recognized valid. They are found on 66 species of marine fishes belonging to 26 families in nine orders. Twenty-two species occur in the Pacific and 17 species in the Atlantic, with two species (C. astralis, and C. zei)occuring in both oceans. The cladistic anaslysis of the genus shows that Chondracanthus can not be subdivided on the basis of the morphology of the transformed legs 1 and 2 (bilobate vs. trilobate), and/or the atrophied tip of antenna (presence vs. absence) in the pygmy male. The adopted phylogenetic hypothesis indicates that C. distortus, C. neali, C. shiinoi, and C. zei are monophyletic and very likely to have co-evoleved with the hosts. Other examples of host-parasite co-evolution are seen between goosefishes (Lophiidae) and lophii-barnardi clade, between lefteye flounders (Bothidae) and janebennettae-psetti clade, and between hakes (Merlucciidae and australis-merlucci-palpifer clade.

Three species of cyclopoids (Acanthochondria sp., Holobomolochus prolixus (Cressey) and Taeniacanthodes haakeri sp. n.) and 1 species of caligoid (Lepeophtheirus bifidus Fraser ?) were recovered from California halibut, Paralichthys californicus (Ayres), caught in Anaheim Bay, California, an area used by the host fish as a nursery. Acanthochondria sp. and L. bifidus ? are not treated due to certain technical problems. The female H. prolixus is redescribed and the male, described for the first time. T. haakeri is described from the female.