MOLLUSCA OF THE ' CHALLENGER ' EXPEDITION. 471 



distinct canal in front. Sculpture. Longitudinals — on the earlier 

 whorls there are sharp, narrow, prominent, slightly oblique, 

 remote ribs ; these increase in number and diminish in distinct- 

 ness, till on the last whorl they are very numerous, crowded, and 

 insignificant : this arises from intermediate riblets, which are 

 almost invisible on the earlier whorls, reaching on the last a pro- 

 minence equal to that of the others ; these are best seen in the 

 sinus-area. Behind the lip is a strong and broad varix, scored 

 with the riblets, and bevelled off to a thin prominent edge. 

 Spirals — the whole surface is covered with fine sharp raised spirals, 

 very often alternating with finer ones in the intervals ; they are 

 separated by shallow square furrows of about the same breadth as 

 the spirals ; at their intersections with the longitudinals they are 

 slightly nodose : in the sinus-area there are only fine crowded 

 spirals, whilst on the snout these are strong and remote. Colour 

 dead porcellaneous white, with a few faint ruddy-brown blotches 

 near the top of the whorls and toward the outer lip. Spire high, 

 conical, scalar. Apex small, sharp, conical, consisting of 3-4 

 ruddy rounded embryonic whorls, the sculpture of which is that 

 of the typical Defrancia group, i. e. the upper half of the whorls 

 is scored longitudinally by very numerous minute, sharp, raised, 

 curved bars, which split into two and cover the lower half of the 

 whorls with exquisite little square-shaped reticulations formed 

 by the crossing of the bars. Whorls 9-10 in all, of regular, but 

 rather rapid increase : they are at first rather broad, but the 

 penultimate is high and the last rather long and narrow ; they 

 rise in steps one above another, being a little flattened above, are 

 well rounded, and have a slight contraction into the lower suture ; 

 the last is produced into a very lop-sided, long, and somewhat 

 oblique and obliquely truncated snout. Suture is strongly 

 marked by the slight contraction of the whorl above, and a con- 

 striction of the shoulder of the whorl below, but is not really 

 deep, for the inferior whorl laps up on that above it. Mouth long, 

 narrow, oblong, sharply pointed above, and produced into an open 

 broadish spout-like canal below. Outer lip forms a regular flat 

 curve to the canal, where it is slightly concave and then straight ; 

 at its junction with the body there is a strongly marked little 

 rounded nick which cuts into the edge, but is bordered by a small 

 encircling pad lying between it and the body- whorl ; this nick is 

 the generic sinus, and the scars of it are marked on all the whorls ; 

 the extreme edge of the lip is thin and sharp, but there is a 



