Polycera quadrilineata(Müller, 1776)

27 May, 2015.
Ardnoe Point, Sound of Jura on the west coast.
25 mm animal at 7 metres. Water temperature 9.5°C.
Sony α6000 in Nauticam housing, 18-55mm lens and 2 x Inon D-2000 flashes.

for more information about this species go to one of the links below
OPK - Opistobranquis

 nudibranchs of the british isles sea slug forum