474 THE VOYAGE OF H.M.S. CHALLENGER 



13. Turritella lamellosa, Watson (Plate XXIX. fig. 6). 



Turritella lamellosa, Watson, Prelim. Report, pt. 6, Journ. Linn. Soc. Lond., vol. xv. p. 229. 



Station 162. April 2, 1874. Lat. 39° 10' 30" S., long. 146° 37' E. Off East 

 Moncoeur Island, Bass Strait. 38 to 40 fathoms. Sand and shells. 



Shell. — Like a Terebra in sharpness and slimuess, perfectly conical, augulated at the 

 edge of the base which is flattish, thin, translucent, and very pale - coloured, with a 

 strong, concavely curved, open, labial sinus. Sculpture : There are veiy many close-set, dis- 

 tinct, curved lines of growth, each of which is produced into a small, thin, sharp, appressed 

 lamella. Spirals — above each suture the superior whorl projects in a slight rounded swell- 

 ing, which slopes gradually outwards on its upper side, is slightly angulated at its greatest 

 projection, and there defined by a fine thread, from which point it is suddenly, but not 

 quite sharply, contracted into the suture. In some specimens this suprasutural swelling 

 is very slight, being checked by a shallow open constriction which lies immediately above. 

 The rest of the whorl is covered by a series of fine threads and shallow open furrows, 6 to 

 10 or 12 in number j varying much in strength and distance. Besides this larger system 

 of sculpture, the whole surface (lamellae and all) is fretted with the most delicate micro- 

 scopic spiral ridges and furrows, which are faintly crimped longitudinally. The apical 

 whorls are pretty sharply carinated and angulated about the middle, and are otherwise 

 almost perfectly polished. Colour yellow ashy white, with a few faint, suffused, small, 

 ruddy blotches, chiefly on the spiral threads, but sometimes continuously curvedly longi- 

 tudinal. The upper part of the spire is uniform white or ruddy. Spire high, narrow, 

 and sharp, with straight profile lines. Apex glossy, porcellanous. The last 2£ whorls 

 contract rather suddenly to the very small, sharply rounded, and prominent point. 

 Whorls 16, perfectly flat, with a tendency to angular convexity in the earlier ones, 

 of very regular and gradual increase ; the last is bluntly angulated on the edge of the 

 base, which is conical and slightly convex. Suture linear and very feebly impressed, 

 defined by the slight swelling of the base of the superior whorl. Mouth small, square- 

 shaped, but higher than broad. Outer lip advances somewhat where it springs from the 

 base, and is here a little drawn in from the edge ; it advances with a slight curve, and is 

 a little patulous toward the outer lower corner, is flat across the base, and advances rather 

 beyond the point of the pillar, where there is a slight open canal. The generic sinus of 

 the outer lip is semicircular. Inner. lip: a flat, but distinct, porcellanous white callus 

 crosses the body-whorl and spreads, but with decreasing thickness, round the base of the 

 pillar. The pillar is narrow, rounded, and perpendicular. H. 1*3 in. B. - 3, least 0*29. 

 Penultimate whorl, height 0-18. Mouth, height 0*19, breadth 0-16. 



Turritella gunnii, Reeve, from " Van Diemen's Land," has a much coarser spire, a deeper suture, 

 and the angle of the base more rounded. In general aspect Turritella declivis, Adams and Reeve, is 

 not unlike, but the Challenger species is of more rapid increase, has not the same projection above 



