366 LITTORINID #. 
striated, almost microscopic, pale yellow shell, of 83-4 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 setz 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 Rissoe. 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 sete. 
R. proxima, Alder. 
R. proxima, Brit. Moll. iii. p. 127, pl. 75. f. 7, 8, and iv. p. 264. 
The animal inhabits a thin, sordid white shell of four 
