Fine de phortáin is ea na Majidae, ina bhfuil thart ar 200 speiceas muirí taobh istigh de 52 géineas, le carapás atá níos faide ná mar atá sé leathan, agus atá mar rinn os a chomhair. Is féidir leis na cosa a bheith an-fhada i roinnt speiceas, agus an t-ainm " portán crúbach " mar thoradh air. Bíonn an eisichreatlach clúdaithe le guairí a gcuireann an portán algaí agus earraí eile ina leith chun gníomhú mar dhuaithníocht .
Roinntear an tuairim is 200 speiceas atá ar marthain agus na hos cionn 50 speiceas atá díothaithe i meascj géineas i 5 fhofhine: [1]
Eurynolambrinae Števčić, 1994
Majinae Samouelle, 1819
- Ageitomaia Griffin & Tranter, 1986
- Anacinetops Miers, 1879
- Choniognathus Rathbun, 1932
- Cyclax Dana, 1851
- Entomonyx Miers, 1884
- Eurynome Leach, 1814
- Jacquinotia Rathbun, 1915
- Kasagia Richer de Forges & Ng, 2007
- Kimbla Griffin & Tranter, 1986
- Leptomithrax Miers, 1876
- Maiopsis Faxon, 1893
- Maja Lamarck, 1801
- Majella Ortmann, 1893
- Microhalimus Haswell, 1880
- Naxia Latreille, 1825
- Notomithrax Griffin, 1963
- Paraentomonyx T. Sakai, 1983
- Paramithrax H. Milne-Edwards, 1837
- Pippacirama Griffin & Tranter, 1986
- Prismatopus Ward, 1933
- Schizophroida T. Sakai, 1933
- Schizophrys White, 1848
- Seiitaoides Griffin & Tranter, 1986
- Temnonotus A. Milne-Edwards, 1875
- Teratomaia Griffin & Tranter, 1986
- Thersandrus Rathbun, 1897
- Tumulosternum McCulloch, 1913
- Wilsonimaia † Blow & Manning, 1996
Micromaiinae † Beurlen, 1930
Mithracinae MacLeay, 1838
- Ala Lockington, 1877
- Antarctomithrax † Feldmann, 1994
- Coelocerus A. Milne-Edwards, 1875
- Cyclocoeloma Miers, 1880
- Cyphocarcinus A. Milne-Edwards, 1868
- Leptopisa Stimpson, 1871
- Macrocoeloma Miers, 1879
- Micippa Leach, 1817
- Microphrys Milne-Edwards, 1851
- Mithraculus White, 1847
- Mithrax A. G. Desmarest, 1823
- Nemausa A. Milne-Edwards, 1875
- Paranaxia Rathbun, 1924
- Picroceroides Miers, 1886
- Stenocionops A. G. Desmarest, 1823
- Teleophrys Stimpson, 1860
- Thoe Bell, 1836
- Tiarinia Dana, 1851
Planoterginae Števčić, 1991