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



the sinus-area ; they are thus very short. The liues of growth are very faint, except in 

 the sinus-area, where, round the top of the whorls, the old sinus-scars form a series of 

 short, sharp, regular, remote, little riblets. Spirals — below the sinus-area is a feeble 

 thread; the periphery of the whorls is marked by two sharp, square-topped threads, 

 which form a double keel ; the upper one is very near the feeble thread above mentioned : 

 the interval between the carinal threads is about four times their breadth ; somewhat 

 more remote, a third thread, equally strong, appears on the last whorl, coming out exactly 

 from the oral angle and defining the base ; above and below this, at about equal distances, 

 are two feebler threads ; the rest of the base is bare, but the entire snout is covered with 

 very small spiral threads. The whole surface is very minutely scored with microscopic 

 spiral lines. Colour frosted white, with a buff apex. Apex : there are four embryonic 

 whorls, which form a high cone with a slightly impressed suture, and rise to a small 

 rounded prominent tip : the sculpture is typical, the tip being scored with some 10 or 12 

 minute sharp spiral threads, while the other whorls have straight bars on the upper part 

 and reticulated bars below, only the part occupied by the straight bars is exceptionally 

 short. Whorls 7 to 8, of regular increase, with a drooping shoulder, a double carination, 

 and a marked contraction to the inferior suture ; the last whorl is very regular in form, 

 with a slightly contracted base, from which projects a small triangular one-sided snout. 

 Suture slightly impressed, flatly but minutely marginated below. Mouth oval, angulated 

 above, and prolonged into a rather broad and longish canal below. Outer lip very regu- 

 larly curved, but drawn out straight along the canal : its edge, which is rather prominently 

 curved below, forms a somewhat low shoulder above, between which and the body lies the 

 wide-mouthed, deep, rounded sinus. Inner lip rather broad and distinct ; it is very early 

 cut off on the short pillar at the very oblique twisted edge, which then runs on as a 

 thin sharp margin to the canal : the junction of the pillar and body is rather deeply 

 concave. H. 0'15 in. B. 0-06. Penultimate whorl, height 0*026. Mouth, height 0*06, 

 breadth 0"03. 



This is a very small species ; but I think one of the specimens is very nearly full-grown. 

 14. Clathurella (?) perparva, Watson (PI. XXII. fig. 8). 



Pleurotoma (Defrancial) perparva, Watson, Prelim. Report, pt. 10, Journ. Linn. Soc. LonJ., vol. xv. 



p. 469. 



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

 350 fathoms. Red mud. 



Shell. — Small, high and narrow, ribbed and spiralled, with convex whorls, a small 

 short body, impressed suture, a high, conical, scalar, small-tipped spire, a rounded base, 

 and a small, short, triangular, one-sided snout. Scxdp)ture : Longitudinals — there are on 

 the last whorl 12, on the earlier one or two fewer, small, straight, rounded ribs, which 



