550 THE _ VOYAGE OF H.M.S. CHALLENGER. 



rounded. Inner lip a thin glaze on the body, but with a distinct edge, which is slightly 

 thickened toward the point of the pillar. H. 021 in. B. 0'084. Penultimate whorl, 

 height 0-035. Mouth, height 0-06, breadth 0"047. 



The peculiar semi-imbricated growth of the whorls in this species recalls somewhat the curious 

 Cerithium dubiwm, Sow. ; but the species differ obviously in size, form, and sculpture. 



14. Bittium cylindricum, Watson (PL XXXIX. fig. 5). 



Cerithium {Bittium) cylindricum, Watson, Prelim. Report, pt. 5, Journ. Linn. Soc. Lond., vol. xv. 



p. 118, sp. IS. 



April 17-18, 1874. Port Jackson, Sydney. 2 to 10 fathoms. 



Shell. — Small, high, narrow, pointed, cylindrically conical, reticulate, tubercled, strong, 

 dark brown. Sculpture: Longitudinals — there are on the last whorl about 25 narrow, 

 posteriorly convex, curved riblets, which cannot be followed from whorl to whorl down 

 the spire, and which hardly appear on the base amidst the strong curved lines of growth 

 found there. These riblets are parted by squarish furrows about as broad as themselves- 

 Spirals — there are on each whorl three pretty equal, squarish, not much prominent, spiral 

 threads, which become prominent themselves and give prominence to the longitudinals by 

 expanding into round-topped tubercles as they cross the riblets ; they are parted by 

 furrows, which are of about the same breadth as themselves ; the sutural furrow 

 is slightly deeper and broader than the others. The edge of the base is squarish, and 

 is defined by a narrow, sharpish-edged spiral thread. The base, which is flatby 

 conical, is plain but for the lines of growth ; the pillar is defined by a minute, sharpish 

 spiral thread, which runs round its top and meets the slit of the canal. Besides 

 these the whole surface of the shell is microscopically scored with irregular lines of 

 growth and fine spiral scratches. Colour dark ruddy brown, uniform all over. Spire 

 high, narrow, pointed, with straight but slightly angulated contour lines ; the first eight 

 whorls expand regularly, so as to form a minute cone, while the last four expand more 

 slowly, so as to give more of a cylindrical shape. Apex small, blunt, rounded, slightly 

 oblique, and a little immersed. Whorls 13, flat, except the last, which is slightly convex, 

 with a somewhat flat but conical base. Suture in the bottom of a deep furrow is concealed 

 by a projection of the inferior whorl. Mouth oval, with a small rounded sinus at the upper 

 outer corner, and a largish and deepish canal running in behind the pillar. Outer lip not 

 expanded, deeply corrugated by the ends of the spirals, with a deep V-shaped fissure 

 forming the canal. Pillar straight, not short, pretty strong, with a rounded, narrow, 

 twisted edge, and a small but not sharp point, which is very slightly reverted. Inner"lip 

 little more than a film on the body and pillar. H. - 27 in. B. 0'064. Penultimate 

 whorl, height 0-031. Mouth, height 0'042, breadth 0-028. 



