1884.] OF THE 'challenger' EXPEDITION. 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 probahility 

 had not, previously to the visit of the ' Challenger,' been visited by 

 any naturalist or collector. 



1. Athoracophorus virratus. (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 

 oritice small, situated about midway between the centre of the dor- 

 sal 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 trian- 

 gular 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 milhm., diam. 10, height 8. 



Hah. Wild Island. 



This species differs from A. bitentaculatus of New Zealand in the 

 more lateral position of the respiratory opening. 



2. Helix (GEOTROCHT;s)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 strife, except upon the two 

 nuclear whorls, which are smooth, pellucid, destitute of the spiral 

 brown lines, and form a vei"y obtuse apex ; the last whorl is obtusely 

 angled at the perij)hery, 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 re- 

 flexed on the outer and basal margin. Columellar margin oblique. 



