346 MALACOZOA. GASTEROPODA. 



the end of February, 1843, 1 have been enabled to 

 give the following particulars : — 



Operculum very thin, horny, transparent, yellowish-brown, 

 semicircular, externally concave, broader and more rounded 

 anteriorly, rugoso-striate, with a small spiral turn at the ante- 

 rior end. Foot very large, roundish-elliptical, thick, with 

 very thin margins, rugose, with very large oblique undulated 

 rugae in its anterior half, its colour dull yellow. Head indis- 

 tinct, broad ; over the mouth a thin-edged rugose flap, having 

 three rounded crenatures, and continuous with the tentacula ; 

 which are rather small, rugose, much depressed or flattened, 

 and taper to a fine point ; externally of the tentacula, on 

 each side, a thin rounded lobe, on which are placed in other 

 species the eyes, of which, however, I cannot perceive any 

 traces. Between the mouth and the foot, and parallel to tbe 

 supraoral flap, is a larger, thin, smooth, somewhat undulated 

 flap, extending on each side nearly to the middle of the foot, 

 in a semicircular manner. The mouth small, proboscidiform, 

 with a large roundish, bright red lingual or pharyngeal mass. 

 The mantle very thin, opening very widely in front, where it 

 forms a thin, dense, yellowish flap, covering the branchial 

 cavity, of which the surface is smooth ; the branchia large. 

 The intestine convoluted, terminating on the right side of the 

 respiratory cavity, the liver dull olive, forming the last, 

 very slender turns of the spire ; the ovary pale yellow. 



Among the numberless Mollusca cast on the beach at 

 the period mentioned above, I found a specimen of a 

 very remarkable species, which, I think, must be re- 

 ferred to the Genus Tritonia, although the respiratory 

 organs had been almost entirely destroyed. 



Tritdnia atrofusca. Brownish-black Tritonia. 



Body oblong, convex above, rugose, the veil repand, 

 plain, the branchise in six tufts on each side ; the co- 

 lour above brownish-black, beneath dull white, on the 

 sides livid purple. Atro-fuscus, black tinged with 

 brown. 



Body oblong, somewhat prismatic, tapering behind to a 

 blunt point. The foot oblong, extending the whole length of 



