Flabellina pellucida (Alder & Hancock, 1843)

20 December, 2012.
Dunollie, Oban on the west coast. 
35 mm animal at 26 m. Water temperature 9.5°C.
Sony NEX-5 in Nauticam housing, 18-55mm lens, SubSee +10 dioptre and 2 x Inon D-2000 flashes.