418 Mr. A. Adams on the Animal and Float 0/ lanthina. 



The animal is entirely blind. I sought in vain for eyes, both 

 at the base and apex of the longer, external, pointed tentacle, 

 and likewise at the truncated apex of the inner and shorter ten- 

 tacular process. No trace of eyes was visible, although an acci- 

 dental dark round spot of pigment may have been mistaken for 

 those organs. 



The head is proboscidiform, and the muzzle is contractile only. 

 The muzzle is susceptible of considerable inflation ; and the 

 apices of the large horny mandibles and the rounded extremity 

 of the tongue, armed with its formidable array of sharp, curved, 

 slender teeth, are observed protruding from the extremity when 

 the animal is engaged in exploring for food. 



Although doubtless the chief food of the lanthina consists of 

 Physalice, Porpita, and Velella, which are usually seen floating 

 in its society, on the surface, in calm weather, yet an occasional 

 Barnacle does not seem to come amiss to the blind Snail of the 

 ocean. From the stomachs of several I extracted fragments of 

 the tufted feet of Lepas, and in one which I examined the Lepas- 

 remains occupied the entire length of the oesophagus. 



On each side of the broad short tongue, or lingual membrane, 

 are two large horny jaws, which, when removed, present an 

 elongate-quadrate form. They are convex externally, very thin, 

 and quite pellucid ; the inner free edge is straight and slightly 

 thickened, the outer attached edge is membranaceous and 

 convex. The anterior lower angle is the pointed apex of the jaw, 

 from which proceed radiating stride and grooves, curving upwards 

 and outwards at the anterior upper angle, and becoming nearly 

 straight as they approach the straight inner margin. 



The mantle, on the left side, has a distinct siphonal fold cor- 

 responding with the angle formed by the union of the inner and 

 outer lips of the shell. The bar-like gills are placed far back 

 under the arched cavity of the shell, in a diagonal direction, 

 and in none of my specimens do they exhibit the appearance of 

 an extruded tuft, as represented in some figures of the animal. 

 ■■' The sides of the foot are furnished with a lateral membrane 

 (without fringes, furbelows, or filaments) which, in lively indivi- 

 duals, is reflexed on the right side on the penultimate whorl of 

 the shell. Anteriorly, this membrane terminates in a simple 

 angular lobe, and posteriorly forms a truncate vertical margin. 

 The foot is narrow, elongated, rounded in front, tapering behind, 

 and not circular and contracted as shown in some figures taken 

 from animals in spirits. The under surface of the foot, like the 

 under surface of the shell, is of a deeper violet-colour than the 

 upper portions ; for these are the parts exposed to the light, the 

 under surface both of animal and shell becoming the upper in 

 the usual position of the living animal. The animal always 



