MOLLUSCA OF THE ' CHALLENGER* EXPEDITION. 473 



threadlets, about three in number, and the first regular spiral 

 below these is stronger than all the rest, and forms a slight keel ; 

 they cover the whole snout. Colour white. Spire high, conical, 

 subscalar. Apex small, sharp, consisting of three (probably, for 

 the extreme tip is broken) embryonic whorls which have the 

 typical _D<?/fomc*a-sculpture, the upper third being straight barred 

 and the lower two thirds reticulately barred ; but the sculpture is 

 very fine. Whorls about 8 in all, of regular but rapid increase ; 

 in form convexly conical, slightly shouldered above : the last, 

 which is narrow, is produced into a convexly conical base and a 

 short oblique-ended snout. Suture is slightly impressed, and is 

 somewhat strongly marked by the swelling of the whorl imme- 

 diately below. Mouth narrowly oblong, bluntly pointed above, 

 where it runs out into the small but rather deeply impressed and 

 rounded gutter of the sinus, and produced below into a broadish 

 canal. Outer lip regularly curved, but at the canal flattened ; 

 the edge forms a regularly curved sweep, prominent in the middle, 

 and retreating into the sinus and canal ; it is slightly contracted, 

 sharp, crimped rather than toothed, thickened a little way within ; 

 in the sinus it is blunted and rounded into a gutter : an exten- 

 sion of the outer lip surrounds the sinus and forms a small pad 

 between that and the body-whorl. Inner lip : there is a very 

 thin glaze on the body and pillar : the edge of the pillar in front 

 has a very slight oblique bend, and is sharply rounded, but scarce 

 twisted. H. 0'31. B. 012. Penultimate whorl, height 007. 

 Mouth, height 0*15, breadth 005. 



This markedly belongs to the same group as the preceding. It 

 has the same Defrancia apex and much the same form as that, 

 and is therefore comparable with the species there referred to ; 

 but it is obviously very distinct from them all. 



63. Pleueotoma (Boesonia) ceeoplasta, n. sp. (KiipoirXaa- 

 tos, waxen.) 



St. 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65°5 r 30" W. 

 JN\ of Culebra Island, St. Thomas, Danish W. Indies. 390 fins. 

 Coral-mud. 



Shell. — High, narrow, biconical, with a tall blunt spire, a 

 slightly impressed suture, and a shortish base : the whorls are 

 feebly ribbed and very obsoletely spiralled. Sculpture : there are 

 on the earlier whorls about 12, on the last two whorls about 

 14 elongated tubercles, which project bluntly and slightly above 



linn, jouen. — zoology, vol. xv. 37 



