Order:
Larvae: Usually without lateral abdominal gills. If gills present, then 4 hooks clustered on segment 10. Thoracic legs each usually with 4 or 5 segments and with 1 or 2 claws; if without legs, head distinctly sclerotized and posterior body (thorax and abdomen) simple, without gills, hair brushes, suckers, or breathing tube. Eye spots usually present, but compound eyes absent.
Family:
Thoracic legs are present with each having four segments and a claw; the labrum is distinct; the abdomen has 9 segments and distinct tufts of gills in the anal region but without a lid-like operculum.