Polycera ocellata Alder & Hancock;
Up to 20mm long. Edge of reduced mantle forms a short frontal veil, cleft at centre, with about 8 short pale lobes [image1]. Mantle edge continues from veil as a tuberculated ridge along each side to rear of gills, terminating in large, bright white, slightly branched branchial lobe . Ground colour of body dark brown to olive green or grey-green, broken into a network by numerous broad low pale tubercles. Translucent, showing fawn viscera near gills. Colours paler on juveniles .
Tall, coloured as body, smooth conical base, 7- 9 widely spaced yellow tinted lamellae  . Apex produced with low domed summit. On 2mm juveniles, stem shorter, 6 lamellae .
Three, or five, near highest point of dorsum . Partially tripinnate, pale shade of body colour, often with fawn marks.
Ventrally, semicircular, yellowish mottled dull green . Surrounds of mouth swollen, meeting to form a Y. Folded, flattened, rectangular, lateral oral-lobes . Dorsally, mantle edge forms lobed veil .
Sole yellowish mottled dull green . Translucent; fawn viscera visible through sole below gills. Propodial expansion can extend  and contract . When animal viewed laterally, upper surface of foot periphery forms grey-white band sprinkled with dull green around base of body . Foot often folded together  when removed from thin stemmed polyzoan prey.
Palio dubia (EML)
- Small isolated tubercles, not breaking ground colour into a network.
- 12 or 13 closely packed lamellae on short stout rhinophore.
- Sublittoral, rarely if ever intertidal. (Many records confuse/combine P.dubia and P.nothus.)
On lower shore, and sometimes sublittorally to 30m, feeding on Bowerbankia spp. (Natuurlijkmooi) Difficult to detect on shore; best sought by examination under magnification of sessile polyzoans in water. Simultaneous hermaphrodite. Spawn mass a laterally compressed cylinder (Seaslugforum) deposited April - September in a loose angulated coil, whitish or tinted rose.
Britain, Ireland, southern Sweden and coasts up to Arctic Circle on both sides of North Atlantic, but some off-shore records may be P. dubia ( GBIF map). Mediterranean records uncertain because of confusion/combining of P. dubia with P.nothus, but correctly identified 2011 from Croatia . Scattered finds around Britain and Ireland, but probably under recorded because of its camouflage. (UK interactive distribution map.NBN.)