Mandible with proximal endite transformed into a huge gnathobasic coxa, which fuses with the basipodite in a strange way during early ontogeny. Finally, only a small band still indicates the former division, while endopod plus a fraction of the basipod and the exopod rest on the basal portion which is Not the coxa and Not the basipod but a kind of syncoxa. Yet we have discovered up to 6-8 postmandibular limbs in late larval stages of some species and also trunk portions, thus presenting us more questions about the final design of these creatures. Traditional taxonomy based on shell characters. 1 shows an antenna and mandible sticking together.
Arrows point to original insertion area of the lost exopods.
2 shows the mandible from the anterior, coloured as in other pictures of the series to enhance the limb portions. 3 is the view of the inner edge. All enditic protrusion of the limb portions have grinding ridges rather than setae. 4 shows a postmandibular limb. Description of shields and taxonomy.