is a slug with no visible shell when alive, but it and L. latens
are more closely related to the majority of sea snails, especially the cowries [image 13
], than to the bulk of sea slug species.
Length to 23mm, width to 16mm. Flexible, profile varies between dome 
and almost a cone 
. Large irregular tubercles on surface 
. Sometimes, outer layer of mantle is sloughed 
, leaving surface smoother. Ground colours include lilac-grey 
, buff, whitish or grey-brown. Surface often marked white, orange, yellow, black, or red to mimic sessile animals such as ascidians [17
, sponges [EML]
and barnacles [2
]. Occasionally, white animals 
resemble L. latens
with yellow marks near the edge of the mantle, and fine black stipple with greyish discs resembling Tridemnum
); differentiation then depends on length and shell spire 
. Front edge of mantle curved into a cylindrical siphon 
with a cut along anterior face, so can be uncurled 
at times. No gills or tentacles on the dorsal body surface. Smooth tentacles and no snout on head 
. Underside of foot 
paler than dorsal body surface. Slit runs across underside of foot near front edge.
Height (longest dimension) of shell 
up to 12mm, width to 8.5mm. Permanently enclosed in body, fragile, translucent white. Periostracum, thin, transparent, slightly yellowed 
. Large aperture, so boat or ear shape. Final whorl of short spire protrudes beyond outer lip of aperture when shell viewed from above or below, but apex may be recessed. Rarely washed up intact.
There is possible ambiguity over shell sizes in published accounts because of difficulty in measuring conventional height (apex to furthest point of aperture) of these fragile and unusually shaped shells, and perhaps identification confusion in collections of L. perspicua and L.latens shells. Longest dimension of shell is usually half length of body, or slightly more.
Key identification features
Some pale animals resemble L. latens, and require examination of shell spire for positive identification if length of animal 10mm or less, .
Resembles a dorid sea slug but has anterior siphon  and no tentacles or gills on dorsal surface.
Adult body up to about 23mm, shell about 12mm longest dimension .
Body dorsum usually heavily tuberculated  .
Body profile dome  to almost cone .
Body ground colour varied, including lilac-grey.
Short spire protrudes  beyond outer lip of aperture when shell viewed in plan.
Rarely, if ever, over 10mm body length or 5mm shell longest dimension. Comparison .
Body dorsum nearly smooth, with a few small tubercles.
Body profile almost flat to upturned saucer, not dome.
Body ground colour can be white (also light-sandy brown, or yellowish buff) but never lilac-grey.
Spire barely perceptible, does not protrude beyond outer lip of aperture when shell viewed in plan.
References and links
Fretter, V. and Graham, A. 1962. British prosobranch molluscs. London, Ray Society.
Graham, A. 1988. Prosobranch and pyramidellid gastropods. London.
McMillan, N.F. 1939. The British species of Lamellaria. J. Conch. Lond
: 170-173. Image and extract at 
Smith, I.F. 2011. Sloughing by Lamellaria perspicua. Mollusc World 27: 6
Yonge, C.M. and Thompson, T.E. 1976. Living marine molluscs. London.
Picton, B.E. & Morrow, C.C., 2010. Encyclopedia of Marine Life of Britain and Ireland
) for ascidian images.