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



with the exception of microscopic radiating lines of growth, is the only ornament of the 

 flat and very slightly conical base. Colour pure somewhat translucent white. Spire high 

 and conical, but contracting very little, and hence more cylindrical than usual. Apex 

 very blunt, but almost mucronated ; this arises from the prominence of the upper of two 

 tumid threads wilich ornament the three embryonic whorls. Of these threads the lower is 

 the larger, but the upper is at first the more prominent, and at its origin stands up 

 minute, round, and projecting, like a small eccentric blunt spike, reminding one of the 

 mucronated mamillary plug of some of the Caecums. This embryonic shell is smooth 

 and glossy, but has some faint trace of spiral sculpture. Whorls 12, of very gradual 

 increase, flat on the sides, constricted below, flat and hardly conical on the base. Suture 

 well defined by the contraction of the whorl above it, and by a minute thread on which 

 it projects. Mouth angulately oval, with a small straight canal in front. Outer lip 

 hroken. Pillar perpendicular, straight, short, narrow, pointed. Inner lip a thickish 

 porcellanous glaze. H. 0*24 in. B. 0"06. Penultimate whorl, height 0'03. Mouth, 

 height 0-032, breadth 0'02. 



This species has some resemblance to Triforis suturalis, Adams and Reeve, but is easily distin- 

 guished from that by its blunt apex and the less sunken suture. The apical spike faintly recalls the 

 very remarkable tip exhibited by Stilus insignis, Jeffr. (Proc. Zool. Soc. Lond., 1885, p. 52, pi. vi. 

 tig. 1). In the figure (7, pi. XLIII.) at the end of this volume, the artist has drawn the apex some- 

 what too much like a plug. I do not think, however, that it is really a plug, and the form is 

 constant in all the three specimens of the shell which were brought home. 



5. Triforis infiata, Watson (PI. XL. fig. 1). 



Cerithium {Triforis) inflatum, Watson, Prelim. Report, pt. 5, Journ. Linn. Soc. Lond., voL xv. p. 103, 



ep. 4. 

 Triforis infiata, Dall, Moll. "Blake" Dredgings, Bull. Comp. Zool. Harvard Coll. Cambridge, 

 vol. vi. No. 3, p. 81. 



Station 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" W. Off Culebra 

 Island, AVest Indies. 390 fathoms. Pteropod ooze. 



Habitat. — Yukatan Strait, 640 fathoms (Dall). 



Shell. — Small, narrow, conical, sobd, opaque, glossy, with a blunt inflated apex. Sculp- 

 ture: Longitudinals — there are on the last whorl 16 rows of small rounded but not blunt 

 tubercles, whose tips are tilted up the spire. These rows more or less continuously run 

 obliquely down the spire in lines from left to right ; the hollows which part them are in 

 form much like themselves ; there are also faint microscopic scratches on the lines of 

 growth. Spirals — on each whorl the tubercles are arranged in two spiral rows, parted by 

 a triangular furrow, narrower than the tubercled spirals. Below the under row of tubercles 

 is a broader furrow, in the bottom of which runs the suture on the spireward face of a fine 



