Defining charaters:    Gut coiling pattern, anterior part of gut passes to the left of esophagus and stomach (right in both nonteleosts and other teleosts); premaxilla firmly fixed to skull; bite between basihyal teeth and endopterygoid.

Diagnostics: generally large path of parasphenoid teeth

Membership:    all freshwater. Arawanas (Tropical species, two in Africa, one in Asia, three Souht America and two Australia) Airbreathing known in at least Arapaima, Heterotis is unusual in being primarily a planctivore and in haveing no parasphenoid teeth and reduced hyoid. mormyrids (elephant noses, baby whales, etc.) 300 species all electrogenic, weakly; greatly enlarged cerebellum. Notopterids - knie fishes of Asia and Africa: few species Undulating locomotion, air breathers, large bony tongue. Hiodontids only North American representatives; two species.