LITTORINA. 347 
plain, light brown, subcarinated variety of that form of the 
L. vincta termed “ quadrifasciata,” which I have seen with 
the same oblique epidermal laminz; but as the animal of the 
“crassior”’ has not been observed, this view cannot be received 
as certam. Though I have only examined the L. pallidula, 
I have little doubt that in all essentials the other species 
called Lacune agree with this type of a section of the Lit- 
torine, making allowance for the variation of species. I have 
given copious notes of the L. littoralis i1 comparison with 
the Littorina pallidula, mihi, and leave it to malacologists 
to draw their own conclusions, reserving to myself, as a 
finale, a short comparative summary. 
L. tirroratts, Linn. et nobis. 
L. littoralis, Brit. Moll. 1m. p. 45, pl. 84. f. 3-7. 
Animal spiral; mantle pale yellow, fleshy, but even with 
the margin of the aperture. The head is a cylindrical wrinkled 
muzzle capable of considerable extension, usually pale red on 
the neck, but the colours are very variable in this species, 
being yellow, orange, red-brown, and occasionally all the hues 
of lead-colour to nearly black. The under part of the foot is 
always white, or yellow-white. The buccal disk is pale yellow, 
subcircular, with a vertical fissure, within which the white 
riband-like spmy tongue is seen at its alternate opening and 
closing; it is when extracted nearly an inch long, and the 
anterior folded jaws are supported by the usual corneous 
plates and buccal apparatus. The tentacula are pale yellow- 
brown, each having two fine longitudinal lead-coloured lines 
running laterally from base to pomt, long, setose, conically 
tapering to not a very fine point ; eyes small, on short offsets 
at the external bases. Foot at rest subcircular, in action an 
elongated oval, well rounded in front and behind, constricted 
moderately at the anterior third of its length, the other two- 
thirds margined with light drab opake transverse flakes, 
posteriorly puckered or jagged, with a central longitudinal 
depressed line. The anterior part of the pedal disk forms a 
terminal arcuated channel, which gives that part of the foot 
