Lungfishes (Sarcopterygii, Dipnoi), along with the coelacanth, are considered to be the most primitive living fishes.  There are three families and six species.  Four species are found in the family Protopteridae (African lungfishes) and one species each in Ceratodontidae (Australian lungfish) and Lepidosirenidae (South American lungfish).

Family Ceratodontidae

    Australian Lungfish (Neoceratodus forsteri)

Family Protopteridae

    African Lungfishes

    West African Lungfish (Protoperus annectens)

    Marbled African Lungfish (Protopterus aethiopicus)

    Slender/Spotted African Lungfish (Protopterus dolloi)

    Gilled African Lungfish (Protopterus amphibius)

Family Lepidosirenidae

    South American Lungfish (Lepidosiren paradoxa)