KEPORT ON THE GASTEROPODA. 619 



Two or three species, but especially Ilissoina artensis, Montrouz., present somewhat of the same 

 character of mouth and basal lip as this species, but none so strongly as it does. 



9. Rissoina mercurialis, 1 n. sp. (PI. XLVI. fig. 8). 



Station 186. September 8, 1874. Lat. 10° 30' S., long. 142° 18' E. Wednesday 

 Island, Cape York, North-east Australia. 8 fathoms. Coral mud. 



Shell. — Eather high and narrow, conical, obliquely ribbed, feebly spiralled, with a tall, 

 small, bluntly rounded apes, rather rounded whorls, an impressed suture, and a short 

 broad rounded base, which in front is minutely constricted and bordered with a strongish 

 cord. Sculpture: Longitudinals — the whorls are crossed by strongish but not high 

 rounded ribs, parted by rather wider furrows, which run down the spire from whorl to 

 whorl a little obliquely ; they persevere to the base ; of these, on the last whorl there are 

 about 15, the last forming a strongish rounded varix on the back of the lip. Spirals 

 — very fine microscopic scratches fret the whole surface, with distant very slight threads, 

 of which the three on the base are strongish ; the constriction round the point of the base 

 is small, but not narrow ; the cord in front is strongish, and is scored by the longitudinal 

 ribs. Colour white. Spire rather high and narrow, subscalar, with faintly convex profile 

 lines. Apex small, consisting of two depressedly tumid smooth embryonic whorls, of 

 which the extreme tip forms a minute flat dome. Whorls 8t=? in all, somewhat high and 

 narrow, convex in outline, being contracted above and below ; the last is rather long, and 

 has a full round base. Suture impressed, slightly constricted on the upper whorls, very 

 little oblique, but somewhat more so below. Mouth pear-shaped, little oblique, pointed 

 above, produced into a runnel below. Outer lip scarcely sinuated above, but hollowed 

 into a strongish gutter below ; its edge is nearly level and thin, being bevelled off from 

 the outside, where the strongish varix makes it pretty thick ; its direction above is nearly 

 straight ; across the base it curves freely. Inner lip barely concave ; it is carried by a 

 thinnish pad obliquely across the body to the point of the pillar, which is very faintly 

 toothed, but not truncated in front. H. 0*16 in. B. 0-067. Mouth, height 0-058 

 breadth 0-044. 



The small produced rounded tip of this species is very characteristic. The specimens vary 

 in size. 



10. Rissoina honoluluensis, n. sp. (PI. XLVI. fig. 9). 

 July 1875. Eeefs off Honolulu. 40 fathoms. 



Shell. — A little high and narrow, conical, rather straight ribbed, very feebly spiralled, 

 with a somewhat truncated spire, a minute subconical apex, shortish subconical whorls, 



1 So called from the island. 



