Anterior structures of larval stages (II) to (IV) of Homarus gammarus. Rostra not to scale; note the spines (marked by arrows) in stage (III). Antennula and antenna. Right appendage in anterior (upper row) and posterior (lower row), besides (II) antenna, which is a left one and flipped. Labeling only given in one instance due to the similarity of the structures throughout all stages. ba = basipod; cx = coxa; en = endopod; ex = exopod; fl = flagellum; if = inner flagellum; of = outer flagellum.