Two new genera and nine new species of hydroids are described based on deep-water material collected from off New Caledonia during various expeditions of the French Tropical Deep-Sea Benthos program. Caledoniana gen. nov., provisionally included in the family Sertulariidae Lamouroux, 1812, presently comprises three new species, viz. C. alata sp. nov., C. decussata sp. nov., and C. microgona sp. nov., while an additional group of three new species, is accommodated in the new sertulariid genus Solenoscyphus gen. nov.: S. candelabrum sp. nov., S. decidualis sp. nov., and S. striatus sp. nov. Furthermore, three new species of Hincksella Billard, 1918 (family Syntheciidae Marktanner-Turneretscher, 1890) are described, namely H. cornuta sp. nov., H. neocaledonica sp. nov., and H. similis sp. nov.
New species, western Pacific, deep-water.