CHEMKETZIA. 419 



rounded sublanceolate points. The eyes are imbedded in the 

 skin at the internal bases, but not quite so close together as 

 in some other species. Foot short, truncate in front, slightly 

 notched in the centre, labiated, rounded behind when at 

 rest ; somewhat elongated, though not much pointed, on the 

 march ; it carries the very light horn-coloured operculum of 

 suboval form, with oblique striae of growth, on a simple upper 

 lobe advanced to nearly the junction of the foot with the 

 body. The foot has an inconspicuous central longitudinal line 

 on the sole. 



It inhabits in sufficient abundance the littoral zone at Ex- 

 mouth ; we have often taken in one search 100 live specimens ; 

 it is, I believe, a strictly littoral species ; those taken in the 

 coralline district have turned out, on examination, slender 

 young Chemnitzia acuta. 



CH. UNIDENTATA, Montagu. 

 Odostomia unidentata, Brit. Moll. iii. p. 264, pi. 95. f. 7, 8. 



Animal spiral, bluish hyaline-white. Mantle even with the 

 shell. Rostrum on the march extended beyond the foot, 

 compressed, bevelled at the margin, entire, truncate in front, 

 varying less in figure than its congeners. Tentacula short, 

 broad, awl-shaped, setose, blunt, with a fine transparent 

 line through their centres. The eyes are within the internal 

 bases, close together, not raised, fixed on the connecting 

 membrane. The foot is short, truncate, slightly eared, but 

 not in the least emarginate in front as in Chemnitzia acuta, 

 or even hollowed-out like that of C. pallida, rounded poste- 

 riorly, sloping to a broad, obtuse, lance-shaped terminus, and 

 carries on the posterior upper surface of a scarcely perceptible 

 operculigerous lobe, a light corneous, suboval, simply striated 

 operculum. The anterior portion of the sole of the foot is 

 flake-white, the posterior hyaline, with a fine longitudinal line 

 only in the centre of that part. The sole of the foot is divided 

 from the upper pedal disk by a shallow groove, giving the foot 

 a labiated aspect. 



This species differs little from C. acuta ; the foot not being 

 emarginate is the principal distinction, and the tentacula are 



2 E 2 



