The fourth post-oral limb is a lobed plate, usually not distinctly segmented, and the fifth a uniramous pediform leg.
The antennules are uniramous, the others biramous, and all three pairs are used in swimming.
The Crustacea could not possibly be derived from an ancestor with two pairs of uniramous antenn.
Crustacea with one pair of uniramous antenn, and possessing facial sutures.
The anterior of the three pairs of Nauplius appendages (At1) is uniramous, and the two posterior (At2, and md) are biramous.
The adult chilopod lacks the antennules, and all of the other appendages, with the exception of the maxillul, are uniramous.
The anterior of these (at 1) is uniramous, and usually formed of three joints which bear bristles on their under surface.