MOLLTJSCA OF THE ' CHALLENGER ' ESPEDITIOIf. 251 



die out at the point of the snout ; they are parted by hollowed 

 furrows which are rather broader than they ; both ribs and 

 furrows are scratched with very fine, almost microscopic lines of 

 growth, which coincide with the course of the ribs ; in the furrows 

 a few of these lines are slightly stronger than the rest. Spirals — 

 below the sinus-area is a very slight angular projection of the 

 whorls, which is made more marked by a thickening and elevation 

 of the ribs at this point ; this is a feature which on the earlier 

 whorls is very distinct, the whole rib being individualized by the 

 central nodule into which it rises ; but further on these nodules 

 lose in importance. At the top of each whorl and close to the 

 suture lies a small flattened thread, rising into minute longitudinal 

 nodules at the ribs ; below this and above the angulation is a 

 slight furrow where the scars of the old sinuses occur. In all 

 this part the surface of the shell is covered by minute spiral 

 threads which lower down become stronger ; they are parted by 

 minute furrows of about the same breadth as the threads ; 

 these are all exquisitely fretted by the longitudinal scratches. 

 Colour greyish, polished with a very beautiful silvery sheen 

 on the whole surface. Spire conically cylindrical, the body-whorl 

 being small and the apex broad in proportion to the size of the 

 shell ; the profile-lines are hardly interrupted by the sutures. 

 Apex consists of I5 broad, depressed, and flatly rounded, smooth 

 whorls. Whorls 8, of very slow increase, short, the last very 

 small, beiug scarcely at all more tumid than the rest, and having 

 a short conical base ; the snout is very short ; there is a small 

 constriction round the top of each whorl ; and the profile-lines are 

 faintly angulated, but are very slightly convex. Suture fine, but 

 well marked, being slightly impressed and defined by the slight 

 swelling round the top of the inferior whorl ; the superior whorl 

 scarcely contracts towards it. Mouth pear-shaped, with a slight 

 angulation at the top and a very short canal below. Outer lip 

 evidently thickened, but chipped in the only specimen present ; 

 it runs with an almost continuous slightly convex curve from 

 the body to the canal, where the curve is slightly and shortly 

 flattened ; the sinus is very shallow and open. Inner lip 

 thickened and raised on a small but defined callus ; it runs straight 

 across the body to the base of the short, thick pillar, down which 

 it proceeds direct and parallel to the slightly prominent callus- 

 edge on the left ; the point of the pillar is rounded and blunt. 



