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Show 1884.] OF T H E ' C H A L L E N G E R ' E X P E D I T I O N . 263 differently coloured. Two are olivaceous, and dotted over with small triangular yellowish black-bordered spots, the third being more yellow and minutely speckled all over with black. Although the shells differ so much in painting, their opercula are precisely similar, agreeing perfectly with the description given by Martens in the work referred to previously. ADMIRALTY ISLANDS. Of the twelve species of land and freshwater Mollusca obtained at these islands nine appear to be undescribed. This is not altogether surprising, as they were chiefly collected in a small island (Wild Island) off the north-west of the main island, which in all probability had not, previously to the visit of the ' Challenger,' been visited by any naturalist or collector. 1. ATHORACOPHORUS VIRGATUS. (Plate XXII. figs. 1,1a.) Animal (in spirit) nearly three times as long as broad, widest across the middle, much flattened and somewhat tapered posteriorly, convex above, not carinated, of a buff colour, with five irregular stripes down the back of a blackish tint, smooth, with only faint indications of a central and lateral groove, as in the type of the genus. Foot very broad, uniformly buff, thin-margined at the sides. Respiratory-orifice small, situated about midway between the centre of the dorsal surface and the margin of the foot; from the opening a narrow groove runs obliquely forward to the middle of the back, and, then bifurcating, passes outside the ocular tentacle on each side. Oral opening (in contraction) surrounded by a thickened rim, tripartite above. Horny jaw with a concave cutting-edge and a small triangular projection at the middle, laterally produced beyond the side margins. The shell is represented (one specimen only has been examined) by eight minute calcareous particles of different shapes and sizes (the largest being about 1| millim. long) situated on the central line of the back a little in front of the respiratory orifice. Length 27 millim., diam. 10, height 8. Hab. Wild Island. This species differs from A. bitentaculatus of New Zealand in the more lateral position of the respiratory opening. 2. HELIX (GEOTROCHUS) MOSELEYI. (Plate XXII. figs. 2, 2 a.) Shell imperforate, obtusely and depressedly conoid, moderately solid, seldom totally whitish, generally encircled with one or more narrow brown lines. Whorls 4, convex, sculptured with fine lines of growth and minute indented wrinkly striae, except upon the two nuclear whorls, which are smooth, pellucid, destitute of the spiral brown lines, and form a very obtuse apex ; the last whorl is obtusely angled at the periphery, convex beneath, and descends obliquely in front rather suddenly. The aperture is a little oblique, and exhibits the external banding. Peristome white, much expanded and reflexed on the outer and basal margin. Columellar margin oblique, |