Periphyllidae is a family of jellyfish containing four genera and six species. The most well-known member of the family, Periphylla periphylla, is usually considered a deep-sea species, but it forms large blooms in surface waters of Norwegian fjords. Genera Nauphantopsis Nauphantopsis diomedeae Fewkes, 1885 Pericolpa Pericolpa campana (Haeckel, 1880) Pericolpa quadrigata Haeckel, 1880 Periphylla Periphylla periphylla (helmet jellyfish) (Péron & Lesueur, 1810) Periphyllopsis Periphyllopsis braueri Vanhöffen, 1902 Periphyllopsis galatheae Kramp, 1959 References Taxa named by Ernst Haeckel Cnidarian families Coronatae