MORE DETAILED ACCOUNT at https://flic.kr/s/aHskufMVjk
Up to 30mm long. Smooth body, no ridges. Translucent-white covered in well defined orange and black pigment marks. Rhinophores enclosed by sheath for almost full height on all sides, except inner face.
Three or five gills near centre of back. Large club-like lobe behind gills at each side. Head lacks oral veil with elongate processes.
Polycera quadrilineata (Müller, 1776) http://www.conchsoc.net/node/5425
Occasionally, has black and orange marks on body.
Oral veil with four to six yellow elongate processes.
No sheath enclosing rhinophores.
Mainly sublittoral, occasionally at ELWS.