Class. Order. Sub-Order. Family. Sub-Family. HYDROZOA (p. 249) +-- ELEUTHEROBLASTEA (p. 253). +-- MILLEPORINA (p. 257). +-- GYMNOBLASTEA (ANTHOMEDUSAE) (p. 262) | +-- Bougainvilliidae (p. 269). | +-- Podocorynidae (p. 270). | +-- Clavatellidae (p. 270). | +-- Cladonemidae (p. 270). | +-- Tubulariidae (p. 271). | +-- Ceratellidae (p. 271). | +-- Pennariidae (p. 272). | +-- Corynidae (p. 272). | +-- Clavidae (p. 272). | +-- Tiaridae (p. 273). | +-- Corymorphidae (p. 273). | +-- Hydrolaridae (p. 273). | +-- Monobrachiidae (p. 274). | +-- Myriothelidae (p. 274). | +-- Pelagohydridae (p. 274). +-- CALYPTOBLASTEA (LEPTOMEDUSAE) (p. 275) | +-- Aequoreidae (p. 278). | +-- Thaumantiidae (p. 278). | +-- Cannotidae (p. 278). | +-- Sertulariidae (p. 278). | +-- Plumulariidae (p. 279) | | +-- Eleutheroplea (p. 279). | | +-- Statoplea (p. 279). | +-- Hydroceratinidae (p. 279). | +-- Campanulariidae (p. 280). | +-- Eucopidae (p. 280). | +-- _Dendrograptidae_ (p. 281). +-- _GRAPTOLITOIDEA_ (p. 281) | +-- _Monoprionidae_ (p. 282). | +-- _Diprionidae_ (p. 282). | +-- _Retiolitidae_ (p. 282). | +-- _Stromatoporidae_ (p. 283). +-- STYLASTERINA (p. 283) | +-- Stylasteridae (p. 285). +-- TRACHOMEDUSAE (p. 288) | +-- Olindiidae (p. 291). | +-- Petasidae (p. 294). | +-- Trachynemidae (p. 294). | +-- Pectyllidae (p. 294). | +-- Aglauridae (p. 294). | +-- Geryoniidae (p. 295). +-- NARCOMEDUSAE (p. 295) | +-- Cunanthidae (p. 296). | +-- Peganthidae (p. 296). | +-- Aeginidae (p. 296). | +-- Solmaridae (p. 296). +-- SIPHONOPHORA (p. 297) +-- Calycophorae (p. 305) | +-- Monophyidae (p. 306) | | +-- Sphaeronectinae (p. 306). | | +-- Cymbonectinae (p. 306). | +-- Diphyidae (p. 306) | | | Oppositae (p. 306).