THE MORPHOLOGY OF THE NAUPLIAR STAGES OF SACCULINA-CARCINI (CRUSTACEA, CIRRIPEDIA, RHIZOCEPHALA)

A morphological study was carried out on the four naupliar stages of S acculina carcini using mainly scanning electron microscopy. Frontal ho rns were present and throughout development the typical nauplius limbs remained simple and gnathobases were lacking. Such features are chara cteristic of other lecithotrophic barnacle nauplii. The presence of a vestigial ventral thoracic process was evident on the stage III naupli us and was even more prominent on the stage IV nauplius. These observa tions confirm that the rhizocephalan nauplius is close to the thoracic an nauplius form and lend strong support for the retention of the Rhiz ocephala within the Cirripedia.