Adalaria proxima (Alder & Hancock, 1854)

April, 2001 at En Ceann Feidh, Loch Nan Uamh near Arisaig on the west coast. 
Found on kelp blade at 6 metres, a 16mm long animal.
Nikon 90SX with 105mm 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