390 BEV. B. BOOG WATSON ON THE 



2. Pletjrotoma (Stjecula) tbilix, n. sp. 



St. 150. Feb. 2, 1874. Lat. 52° 4' S., long. 71° 22' E. Be- 

 tween Kerguelen and Heard Island. 150 fms. Rock. Bottom 

 temperature 35 0, 2. 



Shell. — High, very narrow, biconieally fasiform, subsealar, bi- 

 carinated, strong, white. Sculpture. Longitudinals — there are 

 very many unequal, strong, harsh, flexuous lines of growth, of which 

 one every here and there is stronger than the rest. Spirals — 

 there are two keels, of which the upper and stronger lies a little 

 above the middle of the whorls, is sharply pinched out, but has a 

 rounded edge ; there is a drooping, but straight -lined shoulder 

 above, and the whorl is somewhat contracted below it, so that it 

 has considerable prominence ; the lower keel is a rounded, rather 

 prominent thread, which is the more conspicuous from the con- 

 traction of the whorl below it into the suture ; between these 

 two keels, more or less in the middle, lies a thread, which 

 is more marked than any of the others which, coarse, unequal, 

 and interrupted, closely cover the w r hole surface ; of these two or 

 three in the line of the sinus on the shoulder, between the upper 

 keel and the suture, are somewhat stronger, more regular, and 

 swoln than the rest; while just below this point, where the 

 lines marking the lower edge of the sinus run, the surface is 

 almost free of spiral threads. Colour porcellanous white. Epi- 

 dermis extremely thin, smooth, pale yellowish. Spire high, nar- 

 row, subsealar. Apex consists of 1-j embryonic whorls, globose, 

 smooth, and somewhat obliquely pressed down on one side at the 

 extreme point. Whorls 7|, narrow, angulated, with a straight 

 drooping shoulder below the suture, slightly concave between the 

 keels, contracted into the lower suture ; the base is conical, and 

 projects on the right side into a long, narrow, and very slightly 

 twisted snout. Suture a fine, sharp, deeply impressed line. 

 Mouth club-shaped, being oval above, with a (sharpish angulation 

 at the upper point, and being prolonged into a long, rather 

 narrow, but slightly widening canal, which is open in consequence 

 of the oblique cutting away of the pillar-lip. Outer lip, which is 

 thin, sharp, and patulous, with a slight contraction on the edge of 

 the canal, leaves the body nearly at a right angle, and advances 

 with a very slight convexity to the keel, above which lies the 

 deep, thin-lipped, U-shaped sinus, whose lower margin lies pa- 

 rallel to, but a little above, the conical thread ; from the keel the 

 lip has an edge which on the front is first convex and then very 



