332 THE VOYAGE OF ELKS. CHALLENGER. 



forms a regular concave curve) out to the thin, twisted, obliquely truncate edge of the 

 pillar ; this edge runs out beyond the thin labial pad, and forms a sharp margin along the 

 canal. H. 0'55 in. B. 0'31. Penultimate whorl, height 0*1. Mouth, height 0'3, 

 breadth 0-19. 



Compared with Pleurotoma {Thesbia) translucida^ Wats., this has a rather higher and narrower 

 spire, the suture is more oblique, and the last whorl, besides being much shorter, is more tumid 

 above and less so below. 



62. Pleurotoma {Thesbia) platamodes, 1 Watson (PI. XXIV. fig. 3). 



Pleurotoma {Thesbia) platamodes, Watson, Prelim. Report, pt. 9, Journ. Linn. Soc. Lond., vol. xv. 



p. 447. 



Station 149d. January 20, 1874. Lat. 49° 28' S., long. 70° 13' E. Royal Sound, 

 Kerguelen. 28 fathoms. Volcanic mud. 



Shell. — Thin, fusiform, very finely spirally striated, with a short, tumid body-whorl, 

 a high, small, scalar, small-pointed, round-whorled, shallow-sutured spire, a very oblique 

 and scarcely conical base, and a smallish very one-sided square- fronted snout. Sculpture : 

 Longitudinals — there are very slight unequal lines of growth ; and on the lower part of the 

 whorls very slight remote oblique riblets, which entirely disappear on the last whorl. Spirals 

 — fine, very regular and beautiful, sharp, close-set scratchings cover the whole surface. 

 Below the suture a shallow concave trench marks the line of the old sinus ; the lower 

 edge of this broad furrow is defined by a slight thread. Colour white. Spire rather high, 

 conical, scalar. Apex small, ending in a flattish, rounded, slightly raised point. Whorls 

 6, of regular, but rather rapid increase, rounded, without any contraction below ; above, 

 each laps up rather high and thinly on the whorl above ; below this they at once swell 

 out tumidly, but hollowed by a slight concave furrow, from which results the scalar rise 

 of the spire ; the last is tumid, but obliquely contracted on the base, and ends in a small 

 square-fronted snout. Suture very slight and not in the least impressed, but well defined 

 by the furrow below. Mouth large, oval, pointed above, and truncate below at the front of 

 the very short canal. Outer lip a little patulous ; in its arch it is a little gibbous above ; 

 the curve of the edge is nearly semicircular, with a high prominent shoulder, between 

 which and close up to the body lies the deep, funnel-shaped, rounded sinus. Inner lip : 

 a thin narrow glaze crosses the body and advances along the pillar, on which it rather 

 early comes to an end, being cut off by the oblique, curved, and thin edge which runs out 

 to the point of the shell ; this glaze is defined by a small furrow on its outer margin. 

 The pillar is rather long and straight. H. 0"4 in. B. 0"2. Penultimate whorl, height 

 0-07. Mouth, height 0'23, breadth O'll. 



1 <!r\ara{iu&7ie, flattened. 



