384 LITTORINIDZ. 
an inch high, or, in transverse measure, of four rather tumid 
volutions, the first three of small area, the body bemg more 
than #ths of the bulk of the whole. Under powerful lenses, 
in some specimens, the rudiments of the longitudinal costellze 
or striz of Truncatella Montagu are visible, an important 
corroborative character ; the peristome is complete, but sharp- 
edged. The animal is of the palest yellowish-white, sprinkled 
with excessively minute, flake-white points, particularly on the 
sole of the foot, with the slightest tinge of brown on the neck, 
the effect of that colour in the buccal plates declaring itself 
through the membranes. Mantle plaim and thickened at the 
margin. Rostrum annulated, but not so long in proportion 
as in its congener; broad, flat, emarginate at the extremity, 
forming on the right and left a flattish arcuated lobe ; beneath, 
vertically and slightly crosially cloven, having the usual cor- 
neous buccal plates, tongue, and pair of white jaws. Tenta- 
cula very short, broad, flat, rounded at the end, divergent, 
both im quietude and on the march, carried at almost right 
angles with the front of the head, with large eyes and dila- 
table white pupils as in the preceding species, placed not 
positively at their terminations, but on the centre of the 
membrane, at some distance from the extreme points. This 
was particularly remarked; but the very powerful lens used 
would give them that appearance, which of course would 
not be so apparent when viewed by a common glass; though, 
nearer the extremity of the tentacula, the characters are 
precisely those of 7. Montagui, and a similar white pupil is 
a singular coincidence. The neck, as in its congener, has 
the same longitudinal groove or canaliferous lines running 
medially through the rostrum and neck to the branchial leaf, 
and is doubtless an aqueduct. The neck and rostrum in 
quietude appear short; they are so in 7. Montagui, but can in 
like manner be greatly extended, though not proportionately 
so much. For these reasons the cesophageal streamlets and 
nervous ganglions were not seen: but I distinctly observed, 
through the tenuity of the shell, the kidney-shaped respiratory 
apparatus with the constriction at the end nearest to the heart, 
and clearly detected the fine blood-vessels of the reniform loop 
