(Alder & Hancock, 1844)
Seacliff near Dunbar on the east coast.
The larger specimen is approx. 16mm long. This is one of the 4 morphs Picton and Morrow describe.
for more information about this species go to one of the links below
OPK - Opistobranquis
nudibranchs of the british isles
sea slug forum