366 LITTOEINIDJE. 



striated, almost microscopic, pale yellow shell, of 34 rounded 

 volutions. The mantle does not extend beyond the aperture. 

 The colour is hyaline-white, with a trifling exception. Head 

 proboscidiform, having its terminal pale red disk vertically 

 cloven, in which the buccal organs are distinctly visible. The 

 tentacula are moderately long, rounded at the tips, very pilose, 

 the setae springing from them horizontally, but only visible 

 with high powers ; eyes at the external angles, on small, 

 scarcely raised, pale sulphur-coloured eminences. Foot sub- 

 truncate, slightly auricled, labiated or grooved anteally, and 

 long and narrow. Operculigerous lobe small, and not much 

 alated ; no caudal cirrhus was detected ; the light corneous 

 operculum is suboval and paucispiral, fixed nearly at the ex- 

 tremity of the foot. The animal is exceedingly vivacious and 

 free, marching up a glass with singular rapidity. It is very 

 abundant alive in the coralline zone, in 14 fathoms water, off 

 Budleigh Salterton, Devon. 



June 1853. 



Additional remarks. That part of the mantle which lines 

 the upper angle of the aperture has the pendant linear fila- 

 ment so often alluded to in the Rissoa. The operculigerous 

 lobe anteally is not much alated, but posteally it expands in a 

 rounded form. Many lively examples have shown that the 

 caudal part of the upper lobe extends to nearly the end of the 

 main foot, almost coalescing with it, and terminating in a 

 single, short, but decided cirrhus ; and lastly, the upper part 

 of the rostrum is coloured pale dull red-brown ; the under has 

 on each side a patch of bright sulphur-yellow ; the terminal 

 flattish lobes of the rostrum divided by the fissure are rounded, 

 with a very minute external rectangular shoulder to each. It 

 appears that this species is a strict Rissoa, only the ends 

 of the tentacula are more rounded than in the type, and 

 furnished with fine horizontal hairs or setae. 



R. PROXIMA, Alder. 



R. proximo,, Brit. Moll. iii. p. 127, pi. 75. f. 7, 8, and iv. p. 264. 

 The animal inhabits a thin, sordid white shell of four 



