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



beyond the top of the body, and in front goes slightly beyond the point of the . pillar. 

 Outer lip is gently curved in the middle, with a quick bend at either end ; its edge seems 

 to be nearly level, but emarginate iu front. Top contracts rather quickly to a small 

 central tip. Inner lip : a pretty distinct glaze covers the body ; in front of this the 

 narrow pillar projects somewhat obliquely, with a slight twist and prominent edge, and is 

 rather abruptly cut off at the point ; behind it lies a small furrow running up into a 

 minute umbilical chink. H. 0'062 in. B. 0'03. Mouth, breadth at same place, 0"008. 



The Volvula acuta, d'Orb. (Bulla), a Cuban species, is much sharper and more hunchy. Volvula 

 angustata, A. Adams, is more cylindrical and less stumpily pointed above. 



14. Cylickna (Volvula) sulcata, Watson (PI. L. fig. 6). 



Cylichna (Volvula) sulcata, Watson, Prelim. Report, pt. 19, Journ. Linn. Soc. Lond., vol. xvii. p. 326. 



September 7, 1874. Torres Strait, north of Australia. 3 to 11 fathoms. 

 Station 186. September 8, 1874. Lat. 10° 30' S., long. 142° 18' E. Wednesday 

 Island, Torres Strait. 8 fathoms. Coral mud. 



Shell. — Oblong, very symmetrically curved, bluntly pointed above, and still more 

 bluntly in front, white, very faintly spiralled, but with the centre part of the body plain. 

 Sculptwe: Longitudinals — there are very slight lines of growth. Spirals — at the lower 

 end of the shell there are about ten very slight fretted spiral furrows ; those above are 

 rather sparse and irregular, those toward the point are crowded and feeble ; the larger 

 part of the shell is plain, while above are a few spirals still feebler than those in front. 

 Colour translucent white. Mouth arched ; about the middle the arch is flattened and 

 narrowed, broadening a very little above and somewhat more in front ; above, it rises 

 bluntly beyond the top of the body, and in front it just passes the point of the pillar. 

 Outer lip is very little curved in the middle, but bends in toward the axis at either end ; 

 its edge retreats a little above, but only very slightly in front. Top is bluntly and 

 roundly pointed. Inner Up : there is a small transparent pointed pad where the outer lip 

 rises from the tip ; the curve of the body is regular, but just at the top of the pillar is a 

 slight contraction ; the pillar, which has a very faint tooth at its base, is slightly oblique, 

 and markedly twisted out to the very point ; it has a flat expanded and broadening front, 

 with a sharp reverted edge, behind which is a rather strongly marked furrow, 1 but no 

 umbilicus. H. - 074 in. B. 0"034. Mouth, breadth at same place, '005. 



In form this somewhat resembles Volvula angustata, A. Adams, but the sculpture is quite 

 different. Compared to Cylichna acuminata, A. Adams, the apex of the Challenger species is not 

 spike-like and the spiral striaa are stronger. 



1 It is from this feature the name of the species is derived. 



