Diagnostic characters
Shell solid, opaque, with pointed spire, swollen whorls and deep sutures; ornament of numerous spiral ridges which are usually symmetrically V-shaped in section; examine those not on shell base, and see below), sometimes reduced and often eroded. Aperture round, outer lip arising from last whorl almost at right angles to shell axis. Columella short, apertural edge turned out below it slightly. Colour variable, but usually with a tesselated pattern, throat darker than outer surface. Tip of penis often blunt but with a point, its glands small and not reaching the curved base. Ovoviviparous. terminal part of the female duct containing embryos.
Other characters
The shell has 4-5 whorls. The ratio breadth of last whorl/breadth of penult is two or more (breadth = greatest measurement at right angles to shell axis; the breadth of the last whorl measured just above the origin of the outer lip). The area of mantle skirt between the genital duct and the columellar muscle may show red colour in live animals (it is sometimes difficult to be sure of this) and in males the prostate gland extends anterior to the anus. Up to 15 mm high, 10 mm broad; last whorl occupies 75-80% of shell height, aperture 50-60%.
L. saxatilis, the highest littorinid apart from L. neritoides, is typically found in crevices of bedrock at and above the Pelvetia zone. The species is spread throughout western Europe, including the western parts of the Baltic, and is also found on north eastern and north western coasts of North America. A dwarf form with large aperture. L. s. scotia, has been described from algal tufts in Rockall, and another with everted lips (L. s. panda) also from Rockall and Eddystone Rocks probably belongs here.
Some authorities, most recently J. E. Smith (1981), regard the form rudis Matcn, 1797 as a species distinct from saxatilis, though most treat it only as an ecological variant. The differences by which rudis may be recognized are: the spiral ridges are asymmetrical in section, their adapical sides the steeper; the out-turning of the lip below the columella is large: the shell usually shows no tessellated pattern; the throat is not dark; the ratio breadth of last whorl/breadth of penult is 2 or less; the animals occur about the level of Pelvetia canaliculata but prefer damp areas where they may be found under stones; if on vertical surfaces they are not usually in crevices.