LITTOEINA. 347 



plain, light brown, subcarinated variety of that form of the 

 L. vincta termed " quadrifasciata," which I have seen with 

 the same oblique epidermal laminae ; but as the animal of the 

 "crassior" has not been observed, this view cannot be received 

 as certain. Though I have only examined the L. pallidula, 

 I have little doubt that in all essentials the other species 

 called Lacunae agree with this type of a section of the Lit- 

 torina, making allowance for the variation of species. I have 

 given copious notes of the L. littoralis in 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. LITTORALIS, Linn, et nobis. 

 L. littoralis, Brit. Moll. iii. p. 45, pi. 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 spiny 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 point, 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 



