Yellow dorsal ridge on tail extends part (1) or all (2) the way to the gills. No linear processes on the anterior edge of the mantle over the head (3), but the forward-pointing pallial processes at the base of the rhinophores are often mistaken for them in dorsal view (4). Only small parts of the foot (5) protrude in dorsal view.
Menai Strait. September 2016, and June 2018, leg. P. Brazier and L. Kay.