308 THE VOYAGE OF H.M.S. CHALLENGER. 



close up to the top of the whorl, and is small, round, and deep. Inner lip : there is a 

 small thick pad above ; but below it is thin, narrow, slightly turned back on the straight 

 pillar ; but toward the point it is again turned forward on the edge of the blunt and 

 hardly twisted lip. H. 0-63 in. B. 0-26. Penultimate whorl, height 0'13. Mouth, 

 height 0-25, breadth O'll. 



In form, though broader, this species a good deal resembles Pleurotoma barJdicnsis, H. Ad. ; but 

 in all details it is unlike. In form it slightly resembles Pleurotoma (Bela) liarpidaria, Couth., but 

 has the base less elongated and more pinched in, the whorls more cylindrical, and the whole shell 

 more spindle-shaped, with coarser, stronger, and fewer spiral threads, forming tubercles on the ribs. 

 It is not unlike Pleurotoma granularis, E. A. Sin., Brit. Mus., but has narrower, sharper, and more 

 widely parted ribs and a more conical spire. 



38. Pleurotoma (Drillia) horrenda, 1 n. sp. (PI. XXVI. fig. 4). 



Station 122. September 10, 1873. Lat. 9° 5' S., long. 34° 50' W. Off Pernambuco. 

 350 fathoms. Red mud. 



Shell. — Very coarse and strong, long, narrow, with a concave conical base, huge 

 hunchy ribs, and coarse spiral threads. Sculpture: Longitudinals — there are six enor- 

 mous bunchy oblique ribs on each whorl, which die out on the base and at the sinus 

 below the suture, but reach the suture at the bottom of the upper whorls ; they are parted 

 by broad open furrows, which run obliquely to the left and more or less continuously down 

 the spire ; these ribs and furrows are roughened by coarse unequal lines of growth. 

 Spirals— the surface is scored by strong rough threads parted by wider furrows ; these 

 threads are absent in the deep, strong, shallow, sinus-furrow below the suture, in which, 

 however, a few feeble spiral threads are found ; two, a little stronger, marginate the under 

 side of the suture. Colour : the shell is weathered, but seems to have been of a uniform 

 pale tint. Spire very tall, narrow, and conical. Apex broken. Whorls 11 remaining, 

 convex, of slow increase ; the last is hunchy but not large, and is drawn out into a concave 

 base with a broad snout. Suture small, very much distorted by the longitudinal ribs. 

 Mouth small, elongately and gibbously pear-shaped. Outer lip immensely but remotely 

 thickened outside by the last rib, from which it is bevelled off to a narrow edge ; the 

 U-shaped sinus is deep, broad, and strong, close up to the suture but parted from it by a 

 big triangular shelf ; below it the lip edge advances very much and then retreats again in 

 front. Inner lip: there is a thin broad glaze on the pillar, which is very strong, oblique to 

 the left, slightly cut off in front, where alone it is twisted with a thin rounded edge. 

 H. 2-37 in. B. 0'77. Penultimate whorl, height 0"33. Breath of first remaining whorl 

 0'07. Mouth, height 0'98, breadth 036. 



1 " Monstrum horrendum." 



