384 



an inch high, or, in transverse measure, of four rather tumid 

 volutions, the first three of small area, the body being more 

 than fths of the bulk of the whole. Under powerful lenses, 

 in some specimens, the rudiments of the longitudinal costellse 

 or striae of Truncatella Montagui 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 plain 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 crosiaUy 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 in 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 T. Montagui, and a similar white pupil is 

 a singular coincidence. The neck, as in its congener, has 

 the same longitudinal groove or caiialiferous lines running 

 medially tlirough 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 T. Montagui, but can in 

 like manner be greatly extended, though not proportionately 

 so much. For these reasons the resophageal 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 clearlv detected the fine blood-vessels of the reniform loop 



