Order:
Wings developing in wing pads. Mouthparts suitable for chewing. Gills digitiform and located near mouthparts, on neck, sides of thorax, or underside of base of abdomen, never on top or sides of abdomen. Two tarsal claws per leg. Only two tails (cerci).
Family:
The body is dark and can be quite large (up to 2 inches), with profusely branching gills under the thorax and basal abdominal segments; the wing pads are divergent.