KEPORT ON THE GASTEROPODA. 289 



whorls than on the last. Spirals — two-thirds down the whorls is a blunt angulation 

 bearing 4 or 5 fine, close-set, rounded threads ; on the last whorl the angulation is 

 obsolete, but its place is defined by the group of close-set threads ; on the rounded 

 shoulder above these are microscopic striae and very indefinite rounded threads ; below 

 the angulation are 5 or 6 pretty prominent, unequal, narrow, remote, rounded threads ; 

 the one which comes out from the suture at the upper angle of the mouth, and which 

 defines the base, is somewhat stronger than those above it, and this one is succeeded on 

 the base by a series of others, similar, but more remote, with occasionally a finer one 

 between ; on the base they become feebler, less regular, and, on the whole, more remote ; 

 the surface of the shell between these is faintly scored microscopically. Colour por- 

 cellanous white and semi-transparent, from the thinness of the shell. Epidermis an 

 excessively thin, pale yellow, smooth membrane, which is very easily rubbed off. Spire 

 high and conical, and yet almost globose from the rapid increase of the rounded whorls ; 

 its profile-lines are much interrupted by the sutural contractions. Apex consists of 1^ 

 embryonic whorls, and is small, rounded, mamillary, prominent, but a little flattened 

 down on one side. Wliorls 6, of very rapid increase, the last particularly so ; they are 

 very tumid and well rounded, with only a slight angulation, above which is a long convex 

 shoulder, while below it the whorl contracts very slightly ; the last is very large, being not 

 only tumid, but having an elongated base which, though considerably hollowed out on 

 the left side, is very little narrowed on the right, and is produced into a long, conical, 

 largish snout, which projects almost entirely on the right side of the axis. Suture rather 

 broad and deeply sunken, and almost a little canaliculated. Mouth long, large, club- 

 shaped, being oval and bluntly pointed above, and having a long, rather narrow, and open 

 canal below. Outer lip very sharp and thin, a little contracted except along the canal, 

 where it is slightly patulous ; the curve of the lip, which is very steep above, passes over, 

 by a slightly flattened arch and a concave curve below, to a straight line along the canal ; 

 its edge, on leaving the body, retreats rather rapidly to the left, forming the deep semi- 

 circular sinus which occupies the whole shoulder from the suture to the angulation ; the 

 lower edge of the sinus is very low-shouldered, but advances very prominently below, 

 and retreats no more till it reaches the extreme point of the shell. Inner lip is hollowed 

 rather broadly out of the shell-wall, the edge of which rises sharply, but very thinly, 

 outside ; it spreads across the whole of the rather short and early truncated pillar, which 

 has a long, oblicme, rounded, and slightly twisted edge, and which above joins the body 

 with a very slightly concave curve. Operculum pale yellow, thin, oval, broadly rounded 

 in front where the nucleus lies, pointed behind, rather finely roundedly striate in the 

 loop-lines of growth, which are crowded, not on the pillar edge, but on that lying tow r ard 

 the outer lip of the shell. The body of the animal is a pale buff colour, but cannot be 

 extracted without sacrificing the shell. H. 1*6 in. B. 0"65. Penultimate whorl, height 

 0-27. Mouth, height O'l, breadth 0'43. 



(ZOOL. CHALL. EXP. — PAST XLIL 1885.) Tt 37 



