Facelina bostoniensis (Couthouy, 1838)

17 April, 2015.
Inverkip Pier, Firth of Clyde on the west coast. 
28 mm animal at 12 m. Water temperature 8°C.
Sony α6000  in Nauticam housing, 50 mm Zeiss 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