Five bipinnate gills (1) arise from common base in front of anus (2) near centre of back. Large, erect, club-like, glandular ceras behind gills at each side; coloured as body with large, internally opaque-white tip; distract attack from gills, and probably secrete repugnatory substance. Length 11.5 mm. Menai Strait, Wales. September 2015. Diagrammatic inset from Alder & Hancock, Family 1 Plate 21a.