454 ON THE MOLLTTSCA OF THE ' CHALLENGER' EXPEDITION. 



Shell. — Strong, white, dark-brown tipped, bieonical, with a 

 short stout scalar spire, angulated whorls, a roundly contracted 

 marginated suture, and a small body-whorl conically narrowed 

 into a small unequal-sided snout. Sculpture. Longitudinals — on 

 the earlier whorls there are very small, narrow, oblique ribs ori- 

 ginating in a mid-whorl row of tubercles, but on the last whorl 

 the riblets almost disappear : there are fine scratches in the lines 

 of growth ; these are peculiarly sharp and regular in the sinus- 

 area. Spirals — the whorls are bisected by a strong angular keel, 

 sparsely, but regularly, set with small round knobs, from which 

 the longitudinal ribs descend ; below the suture there is a narrow 

 cylindrical collar of two fine contiguous threads : the sinus-area 

 is free of these ; but from the keel downwards the surface is 

 covered by fine narrow rounded threads, separated by broader 

 intervals ; near the keel these are crowded ; on the point they are 

 wider apart, on the base they are most sparse : besides these, 

 there is a delicate microscopic fretting. Colour porcellaneous 

 white, dead or frosted in the interstices, but pellucid and glossy 

 on the spiral threads ; the apex is dark ruddy brown. Spire 

 conical, scalar, shortish, blunt. Apex consists of 3^ cylindrically 

 globose rounded whorls separated by a linearly impressed suture ; 

 they rise to a flattened top, consisting of fully 1-^ whorls, in the 

 midst of which lies the very minute and immersed tip. These 

 whorls are coloured of a deep, rich, translucent, faintly ruddy 

 brown ; the earliest ones, perhaps from rubbing, are glossy, but 

 further on they are crossed by crowded, curved, sharpish, almost 

 microscopic riblets, between which are finely microscopic spirals 

 whose course is not quite uniform. Whorls 7\ ; but the shell is 

 probably not quite full-grown ; they are of very regular and slow 

 increase, broad and short, each one laps up on the one before it, 

 and is there shortly cylindrical, has then a pretty long, concave, 

 and somewhat horizontal shoulder to the keel, which is right- 

 angled ; below this the whorls are cylindrical with a slight 

 contraction downwards to the inferior suture. The body-whorl 

 contracts from the keel downwards, with a convexly conical and 

 very unequally-sided base, produced into a small bluntly pointed 

 snout. Suture a very shallow rounded furrow defined by the 

 infrasutural collar and the contraction of the whorls. Mouth 

 angularly pear-shaped, being truncate above and prolonged into 

 the broadish canal below. Outer lip leaves the body at a right 

 angle, and advances direct to the keel, from which point to the 



