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



10 minute threads: these threads, which are at first almost simple, are by degrees more 

 and more fretted by longitudinals, which break up the threads into minute tubercles : 

 toward the end of the second whorl longitudinal and oblique bars appear somewhat 

 vaguely and confusedly ; but presently the distinct arrangement appears of short little 

 bars above and a net-work on the lower part of the whorls. Whorls 1\ in all, but the 

 shell is very likely hardly full-grown : they are almost horizontal above, with a fiat or 

 faintly concave sinus-area, slightly angulated at the shoulder, and below this cylindrical 

 or a very little convex to the lower suture ; the last is long, a little tumid, with 

 a long pillar-line on the left side, and a small square prominent snout on the right. 

 Suture very slight in consequence of the up-lap of the whorls at their junction, but of 

 course strongly marked by the angulation of the line of junction. Mouth oblong, trian- 

 gularly pointed above, and ending in a very square broadish canal below. Outer lip 

 flatly arched, with a slight angulation below the sinus-area and a marked pinch-in where 

 it turns to form the canal ; its edge-line is very straight and scarcely prominent, but has 

 a high shoulder above, between which and the body lies the deepish, rounded, and open- 

 mouthed sinus. Inner lip very thin and narrow, and dying out very early on the scarcely 

 oblique, twisted, sharp pillar-edge ; its line across the body is very short and convex, but 

 is very concave at its junction with the long, scarcely oblique pillar. H. 0'22 in. B. 0"1. 

 Penultimate whorl, height 0'04. Mouth, height 0'13, breadth 0-04. 



This is like Clathurclla ^?(ffcws, but differs markedly in its more angular outlines and square 

 pmehed-out snout. 



10. Clathurella streptophora^ (Watson), (PI. XIX. fig. 8). 



Pleurotoma (Defrancia) streptophora, Watson, Prelim. Report, pt. 10, Journ. Linn. Soc. Lond., vol. xv. 



p. 464. 



North Atlantic. April or May 1873. (Station not entered.) Over 1000 fathoms. 



Shell. — White, strong, porcellanous, stumpy, with a very short body-whorl, a double 

 necklace of tubercles below the suture, a rather high, small-tipped, buff-pointed spire, a 

 rounded base, small, broadish, reverted snout, and a twisted pillar. Sculpture : Longitu- 

 dinals — there are about 12 narrow ridge-shaped ribs on each whorl : they originate below 

 the sinus-area in conical-shaped little tubercles, and die out at the point of the base ; they 

 are parted by shallow rounded furrows of about three times their breadth. The lines of 

 growth, which are pretty strong, cover the whole surface. Spirals — close below the suture 

 is a row of small, rather coarse, and not quite regular, rounded tubercles, about 24 to 26 

 in number : these form an angulated ring as a subsutural margination ; adjacent to them 

 is the row of more prominent costal conical-shaped tubercles ; the body- whorl below 

 these is feebly striate. Toward the end of the base is a sharpish furrow succeeded 



1 ffTj?Tro^)o'ji)c 7 necklace-wearing. 



