75 genera are assigned to the class HYDROZOA
| Order | Genus | FOP | FOS | LOP | LOS |
|---|
| HYDROIDA | Archaeoantennularia | D | m | D | m |
| HYDROIDA | Archaeocryptolaria | Cm | mMid | O | m |
| HYDROIDA | Archaeolafoea | Cm | uMid-m | O | Cara-m |
| HYDROIDA | Archaeonectris | O | Ashg | S | Ldov |
| HYDROIDA | Cályxhydra | O | Llde | O | Llde |
| HYDROIDA | Crucimedusina | C | Step | C | Step |
| HYDROIDA | Discophyllum | O | Cara-m | O | Cara-m |
| HYDROIDA | Drevoôella | C | Mosc-u | C | Mosc-u |
| HYDROIDA | Eisenackiella | K | Sant | K | Sant |
| HYDROIDA | Flexihydra | O | ? | O | ? |
| HYDROIDA | Gelenptron | Cm | mMid-u | Cm | mMid-u |
| HYDROIDA | Hydractinia | T | Eo-l | R | |
| HYDROIDA | Hydrallmania | K | Maes-u | R | |
| HYDROIDA | Inocaulis | O | Aren | D | Gedi-l |
| HYDROIDA | Kristinella | K | ? | K | ? |
| HYDROIDA | Kullingia | V | u | V | N-Da |
| HYDROIDA | Mazohydra | C | Mosc-u | C | Mosc-u |
| HYDROIDA | Mesokylix | J | m | J | m |
| HYDROIDA | Palaeacmea | Cm | Trep | Cm | Trep |
| HYDROIDA | Palaelophacmaea | O | l | K | Barr-u |
| HYDROIDA | Palaeokylix | O | ? | O | ? |
| HYDROIDA | Palaeonectris | D | Gedi | D | Emsi-l |
| HYDROIDA | Palaeotuba | O | Llde-u | O | Llde-u |
| HYDROIDA | Parleria | K | Ceno | K | Ceno |
| HYDROIDA | Philippinactinia | T | Ol | T | Ol |
| HYDROIDA | Plectodiscus | S | Ludl | Tr | Carn-u |
| HYDROIDA | Protohalecium | Cm | mMid | Cm | mMid |
| HYDROIDA | Protulophila | J | Bajo | T | Plio |
| HYDROIDA | Psammactinia | K | Maes-l | K | Maes-l |
| HYDROIDA | Rhabdohydra | O | Llvi | O | Ashg |
| HYDROIDA | Sphenoecium | Cm | mMid | Cm | mMid |
| HYDROIDA | Veluíbrella | Cm | Atda-u | Cm | mMid |
| LEMNISCATERINA | Cassianastraea | Tr | Ladi-u | Tr | Nori-l |
| MILLEPORINA | Axopora | T | Eo-m-u | T | Ol |
| MILLEPORINA | Axoporella | T | Eo | T | Eo |
| MILLEPORINA | Diamantopora | T | Eo | T | Eo |
| MILLEPORINA | Heterastridium | Tr | Nori-u | Tr | Nori-u |
| MILLEPORINA | Milleaster | T | Mi | Q | Plei |
| MILLEPORINA | Millepora | T | Dani | R | |
| MILLEPORINA | Palaeomillepora | J | Plie-u | J | Plie-u |
| MILLEPORINA | Subaxopora | J | u | J | u |
| SIPHONOPHORIDA | Paropsonema | Cm | u | D | Fras-m |
| SIPHONOPHORIDA | Protolyella | Cm | Atda-l | Cm | m |
| SIPHONOPHORIDA | Rotadiscus | Cm | Atda-u | Cm | mMid-l |
| SPHAERACTINIDA | Cycloporidium | K | Ceno | K | Ceno |
| SPHAERACTINIDA | Globostroma | T | Ol-l | T | Ol-l |
| SPHAERACTINIDA | Parkeria | K | Ceno-l | K | Ceno-l |
| SPHAERACTINIDA | Paronaria | K | Apti | K | Apti |
| SPHAERACTINIDA | Stromactinia | Tr | u | Tr | u |
| STYLASTERINA | Allopora | T | Ol-u | R | |
| STYLASTERINA | Astya | T | Dani | R | |
| STYLASTERINA | Congregopora | T | Dani | T | Dani |
| STYLASTERINA | Conopora | T | Dani | R | |
| STYLASTERINA | Distichopora | T | Eo | R | |
| STYLASTERINA | Errina | T | Dani | R | |
| STYLASTERINA | incertae sedis | K | Maes | K | Maes |
| STYLASTERINA | Pliobothrus | T | Dani | R | |
| STYLASTERINA | Sporadopora | T | Dani | R | |
| STYLASTERINA | Stylaster | T | Eo | R | |
| TRACHYLINIDA | Acalepha | J | Tith-l | J | Tith-l |
| TRACHYLINIDA | Acsaspedites | J | Tith-l | J | Tith-l |
| TRACHYLINIDA | Hydrocsaspedota | J | Tith-l | J | Tith-l |
| uncertain | Delheidia | T | Ol | T | Ol |
| uncertain | Eoporpita | V | u | V | u |
| uncertain | Graptogeitonia | O | ? | O | ? |
| uncertain | Jillua | Tr | u | Tr | u |
| uncertain | Likinia | C | Mosc-u | P | Asse |
| uncertain | Lovcenipora | Tr | u | J | ? |
| uncertain | Ovatoscutum | V | u | V | u |
| uncertain | Plumalina | D | Give-l | D | Fras |
| uncertain | Rhizostromella | K | Ceno | K | Ceno |
| uncertain | Roseoporella | D | ? | D | ? |
| uncertain | Stoliczkaria | Tr | u | Tr | u |
| uncertain | Stoliczkiella | K | Ceno | K | Ceno |
| uncertain | unknown | V | u | V | u |
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FOP = Period of first occurrence
FOS = Stage of first occurrence
LOP = Period of last occurrence
LOS = Stage of last occurrence
Stage abbreviations follow Sepkoski (2002).