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



for the genus and relatively to size, blunt, almost slightly tumid, round, but on one 

 side the extreme tip has the faintest conceivable prominence. Wlwrls 9, of regular 

 increase, though the last is a little disproportionally large, well rounded ; the last, which 

 is slightly tumid, has a very faint trace of angulation below the suture and at the edge of 

 the base, which is flatly rounded and projecting, with a slightly thickened and angulated 

 carination round the umbilicus. Suture linear, impressed, and very slightly oblique. 

 Mouth oval, bluntly angulated above, effuse on the base and slightly so on the outer lip. 

 Outer lip is slightly pinched in at its union with the body ; from this point it runs out to 

 the right with a free curve, but, speedily turning to the left, its course is straight, and 

 here it is prominent, and it becomes increasingly patulous as it curves quickly round to 

 join the pillar. Pillar is not at all oblique, but is slightly concave. Inner lip crosses the 

 body on a thin but sharply-edged pad ; it is thin, sharp, and scarcely patulous on the 

 front of the pillar. Umbilicus : there is a small funnel-shaped trough between the pillar- 

 lip and the angulated edge of the base, but this contracts immediately to a mere 

 chink. H. 0-153 in. B. 0-053. Penultimate whorl, height 0-026. Mouth, height 0-039, 

 breadth 0-03. 



This species is like Aclis ivalleri, Jefir., but certainly distinct; the shell is broader, the whorls, 

 which are fewer (9 instead of 11), are rounder, being less flattened, constricted above and less bulgy 

 below, the spire, which is less regularly conical, is not so attenuated, the apex is not nearly so fine 

 and the surface of the shell is smoother, the longitudinals being less visible, while the malleated 

 structure, which also exists in Aclis walleri, is here even less visible. 



4. Aclis minutissima, n. sp. (PI. XXXIII. fig. 9). 



Station 185b. August 31, 1874. Lat. 11° 38' 15" S., long. 143° 59' 38" E. Off 

 Paine Island, Cape York, North-east Australia. 155 fathoms. Coral sand. 



Shell. — Excessively minute, rather broadly conical for the genus, with slightly convex 

 shortish whorls, an appreciably impressed suture, and a flatly shortly produced base. 

 Sculpture : there are some excessively minute and faint lines of growth. Colour very 

 palely brownish hyaline. Spire conical, high, and, though broadish for the genus, yet 

 in itself narrow in proportion to width. Apex blunt and perfectly rounded, the extreme 

 tip being barely visible. Wlwrls 7, rather short, convex on the sides ; the last has a 

 slightly produced and conical base. Suture shghtly impressed. Mouth oval ; a little 

 pointed above and in front of the pillar. Outer lip thin, curved, and little patulous on the 

 base. Inner lip slightly convex across the body, obtusely angled at the base of the pillar, 

 on which the lip-edge is thin, and is reverted on a small umbilical furrow ; the junction of 

 the point of the pillar and the outer lip is slightly angulated. H. 0'025 in. B. 0*01. 

 Mouth, height 0-008, breadth 0-007. 



