| Iacra | Semelidae | Tellinoidea | Leptarius | Nassariinae | Nassariidae | Buccinoidea | ||
| Icuncula | Capulidae | Calyptraeoidea | Lepton | Erycininae | Lasaeidae | Galeommatoidea | ||
| Ilyanassa | Subfamily uncertain | Nassariidae | Buccinoidea | Leptonotis | Hipponicidae | Calyptraeoidea | ||
| Inoceramus | Inoceramidae | Pterioidea | Leptopecten | Chlamydinae | Pectinidae | Pectinoidea | ||
| Inquisitor | Crassispirinae | Turridae | Conoidea | Leptopoma | Cyclophorinae | Cyclophoridae | Cyclophoroidea | |
| Iredalina | Fulgorarinae | Volutidae | Volutoidea | Leptoscapha | Volutinae | Volutidae | Volutoidea | |
| Iredalula | Colubrariinae | Fasciolariidae | Columbelloidea | Leucodiscus | Skeneidae | Cirroidea | ||
| Irus | Tapetinae | Veneridae | Veneroidea | Leucorhynchia | Skeneidae | Cirroidea | ||
| Iselica | Amathininae | Pyramidellidae | Pyramidelloidea | Leucotina | Amathininae | Pyramidellidae | Pyramidelloidea | |
| Isoarca | Isoarcinae | Nuculanidae | Nuculanoidea | Leucozonia | Peristerniinae | Fasciolariidae | Columbelloidea | |
| Isocrassina | Astartinae | Astartidae | Astartoidea | Levifusus | Fusininae | Fasciolariidae | Columbelloidea | |
| Isognomon | Isognomonidae | Pterioidea | Lilax | Vermiculariinae | Turritellidae | Cerithioidea | ||
| Ithycythara | Mangeliinae | Conidae | Conoidea | Lima | Limidae | Limoidea | ||
| Jagolucina | Milthinae | Lucinidae | Lucinoidea | Limacina | Limacinidae | Spiratelloidea | ||
| Jagonoma | Lucininae | Lucinidae | Lucinoidea | Limarca | Limopsidae | Limopsoidea | ||
| Janiopsis | Buccininae | Buccinidae | Buccinoidea | Limaria | Limidae | Limoidea | ||
| Janupecten | Chlamydinae | Pectinidae | Pectinoidea | Limatula | Limidae | Limoidea | ||
| Jaton | Ocenebrinae | Muricidae | Muricoidea | Limea | Limidae | Limoidea | ||
| Jenneria | Ovulinae | Ovulidae | Cypraeoidea | Limopsis | Limopsidae | Limopsoidea | ||
| Jouannetia | Jouannetiinae | Pholadidae | Pholadoidea | Lindoliva | Olivinae | Olividae | Volutoidea | |
| Jujubinus | Trochinae | Cirridae | Cirroidea | Linga | Lucininae | Lucinidae | Lucinoidea | |
| Jupiteria | Nuculaninae | Nuculanidae | Nuculanoidea | Liochlamys | Fasciolariinae | Fasciolariidae | Columbelloidea | |
| Katelysia | Tapetinae | Veneridae | Veneroidea | Lioconcha | Pitarinae | Veneridae | Veneroidea | |
| Keepingia | Dorsaninae | Nassariidae | Buccinoidea | Lioglyphostoma | Crassispirinae | Turridae | Conoidea | |
| Keliostoma | Diastomatinae | Diastomatidae | Cerithioidea | Liomesus | Buccininae | Buccinidae | Buccinoidea | |
| Kelletia | Buccininae | Buccinidae | Buccinoidea | Liostrea | Ostreinae | Ostreidae | Ostreoidea | |
| Kellia | Kelliinae | Kelliidae | Galeommatoidea | Liotia | Liotiinae | Turbinidae | Trochoidea | |
| Kelliella | Kelliellidae | Glossoidea | Liotina | Liotiinae | Turbinidae | Trochoidea | ||
| Kereia | Dosininae | Veneridae | Veneroidea | Liracassis | Cymatiinae | Ranellidae | Tonnoidea | |
| Kleinella | Amathininae | Pyramidellidae | Pyramidelloidea | Liratilia | Pyreninae | Columbellidae | Columbelloidea | |
| Knefastia | Cochlespirinae | Turridae | Conoidea | Liratomina | Clavatulinae | Turridae | Conoidea | |
| Korobkovia | Propeamussiidae | Pectinoidea | Lirophora | Sunettinae | Veneridae | Veneroidea | ||
| Krachia | Subfamily unnamed | Cerithiopsidae | Ptenoglossa | Lissochlamys | Pectininae | Pectinidae | Pectinoidea | |
| Kuia | Venerinae | Veneridae | Veneroidea | Lithoconus | Coninae | Terebridae | Conoidea | |
| Kurinuia | Verticordiidae | Cuspidariina | Lithophaga | Lithophaginae | Mytilidae | Mytiloidea | ||
| Kurtziella | Mangeliinae | Conidae | Conoidea | Lithopoma | Turbininae | Turbinidae | Trochoidea | |
| Lacuna | Lacunidae | Littorinoidea | Littoraria | Littorininae | Littorinidae | Littorinoidea | ||
| Lacunaria | Lacunidae | Littorinoidea | Littorina | Littorininae | Littorinidae | Littorinoidea | ||
| Lacunella | Elachisinidae | Rissooidea | Livonia | Zidoninae | Volutidae | Volutoidea | ||
| Laevastarte | Astartinae | Astartidae | Astartoidea | Lobantale | Dentaliidae | Dentaliida | Scaphopoda | |
| Laevicardium | Laevicardiinae | Cardiidae | Cardioidea | Lomirosa | Busyconinae | Melongenidae | Buccinoidea | |
| Laevidentalium | Laevidentaliidae | Dentaliida | Scaphopoda | Lonchaeus | Pyramidellinae | Pyramidellidae | Pyramidelloidea | |
| Laevihastula | Terebrinae | Terebridae | Conoidea | Longiconcha | Volutoderminae | Volutidae | Volutoidea | |
| Laevityphis | Typhinae | Muricidae | Muricoidea | Longimactra | Mactrinae | Mactridae | Mactroidea | |
| Lahilia | Lahilliidae | Cardioidea | Lopha | Lophinae | Ostreidae | Ostreoidea | ||
| Laiocochlis | Cerithiellinae | Cerithiopsidae | Ptenoglossa | Lophiotoma | Turrinae | Turridae | Conoidea | |
| Lambis | Subfamily undecided | Strombidae | Stromboidea | Loripes | Lucininae | Lucinidae | Lucinoidea | |
| Lamprodomina | Olivellinae | Olividae | Volutoidea | Lottia | Lottinae | Lottidae | Patelloidea | |
| Lapeirousia | Lapeirousiinae | Radiolitidae | Hippuritoidea | Lowenstamia | Coralliophylidae | Muricoidea | ||
| Lapparentia | Horatiinae | Hydrobiidae | Rissooidea | Loxocardium | Cardiinae | Cardiidae | Cardioidea | |
| Lapparia | Volutomitridae | Mitroidea | Loxoglypta | Macominae | Tellinidae | Tellinoidea | ||
| Laseina | Sportellidae | Cyamioidea | Lucapinella | Fissurellidinae | Fissurellidae | Fissurelloidea | ||
| Latecphora | Ecphorinae | Muricidae | Muricoidea | Lucina | Lucininae | Lucinidae | Lucinoidea | |
| Latirus | Peristerniinae | Fasciolariidae | Columbelloidea | Lucinella | Divaricellinae | Lucinidae | Lucinoidea | |
| Laxispira | Turritellinae | Turritellidae | Cerithioidea | Lucinisca | Lucininae | Lucinidae | Lucinoidea | |
| Ledina | Nuculanidae | Nuculanoidea | Lucinoma | Myrteinae | Lucinidae | Lucinoidea | ||
| Leiomya | Cuspidariidae | Cuspidariina | Lunarca | Anadarinae | Arcidae | Arcoidea | ||
| Leionucula | Nuculidae | Nuculoidea | Lunulicardia | Fraginae | Cardiidae | Cardioidea | ||
| Lembulus | Nuculaninae | Nuculanidae | Nuculanoidea | Lupunovula | Ovulinae | Ovulidae | Cypraeoidea | |
| Lemniscolittorin | Mathildidae | Architectonicoidea | Lutetia | Kelliellidae | Glossoidea | |||
| Lentidium | Lentidiinae | Corbulidae | Myoidea | Lutraria | Lutrariinae | Mactridae | Mactroidea | |
| Lentipecten | Propeamussiidae | Pectinoidea | Lymnaea | Lymnaeinae | Lymnaeidae | Lymnaeoidea | ||
| Lepetella | Lepetellidae | Lepetelloidea | Lyonsia | Lyonsiidae | Pandoroidea | |||
| Lepidopleurus | Leptochitonidae | Lepidopleurina | Polyplacophora | Lyria | Lyriinae | Volutidae | Volutoidea | |
| Leporimetis | Macominae | Tellinidae | Tellinoidea | Lyropecten | Pectininae | Pectinidae | Pectinoidea | |
| Lepsiella | Rapaninae | Muricidae | Muricoidea | Lyrotyphis | Typhinae | Muricidae | Muricoidea | |
| Lepsithais | Rapaninae | Muricidae | Muricoidea | |||||