Duvaucelia lineata (Alder & Hancock, 1848)

27 October, 2002.
Port an Mine, Loch Etive on the west coast. 
At 24 metres in 12 C water, a 20mm long animal, one of several observed during this dive.
Nikon 90SX with 60mm lens in Subal housing and housed SB26 flash

for more information about this species go to one of the links below
OPK - Opistobranquis nudibranchs of the british isles sea slug forum