Eubranchus farrani (Alder & Hancock, 1844)

19 September, 2011.
Manse Reef, Loch Leven on the west coast.
Mating pair of 20 mm animals at 10 metres in 13°C water.
Sony NEX-5 in Nauticam housing, 18-55mm lens, SubSee +10 dioptre and 2 x Inon D-2000 flashes.