Acaulidae Fraser, 1924 (basis of record)
Bonneviellidae Broch, 1909 (basis of record)
Boreohydridae Westblad, 1947 (basis of record)
Bythotiaridae Maas, 1905 (additional source)
Clausophyidae Bigelow, 1913 (additional source)
Eucodoniidae Schuchert, 1996 (additional source)
Eudendriidae L. Agassiz, 1862 (additional source)
Guillea Bouillon et al., 2000 (redescription)
Hydridae Dana, 1846 (additional source)
Hydroidolina (additional source)
Krampella Russell, 1957 (taxonomy source)
Mitrocomium Haeckel, 1879 accepted as Lovenella Hincks, 1868 (additional source)
Mitrocomium cirratum Haeckel, 1879 accepted as Lovenella cirrata (Haeckel, 1879) (new combination reference)
Orchistomatidae Bouillon, 1984 (additional source)
Paracorynidae Picard, 1957 (basis of record)
Protohydridae Allman, 1888 (basis of record)
Siphonophorae (additional source)
Staurophora mertensii Brandt, 1835 accepted as Staurostoma mertensii (Brandt, 1835) (additional source)
Stylasteridae Gray, 1847 (additional source)
Teclaiidae Bouillon et al., 2000 (additional source)
Toxorchis Haeckel, 1879 accepted as Staurodiscus Haeckel, 1879 (source of synonymy)