Shell plate and operculum morphology of Neonrosella vitiata (Darwin, 1854) A anterior view of shell B basal view of shell without body tissue C basal view of shell with body tissue intact D external view of individual shell plates (parietes) E internal view of individual shell plates F (left) close-up on external view of operculum (right) internal view of intact operculum G external view of operculum (one side of both tergum and scutum) H internal view of operculum (one side of both tergum and scutum) I–L tergum I external view J internal view K SEM of internal view L close-up on crests for lateral tergal depressor muscle M)–R) scutum M external view N internal view O SEM of internal view P close-up of crests at edge of basal margin (bm) close to occludent margin (om) Q close-up of crests for lateral scutal depressor muscle R close-up of articular ridge (ar).