REPORT ON THE GASTEROPODA. 61 



Station 56. May 29, 1873. Lat. 32° 8' 45" N., long. 64° 59' 35" W. Bermuda. 

 1075 fathoms. Coral mud. 



Habitat.— OS Havana. 220 to 539 fathoms (Dall). 



Shell. — Small, conical, high-spired, flatly rounded on the base, sculptured, white, dull 

 on the surface, with a bright nacreous gleam shining through. Sculpture : Spirals — on the 

 upper part of the last whorl there are two rows of tubercles, the first and weaker is close 

 up to the suture ; the second is a little lower than the middle, and its tubercles are strong. 

 Of these there are on each row twenty to twenty-five ; they are scarcely connected by a 

 spiral thread. The periphery is sharply angulated and defined by an expressed and 

 tubercled carina, the tubercles of which are hardly so strong as those of the second row 

 above, which from its larger points projects quite as much as the carina. On the base there 

 is an infra-carinal furrow and three or four sharpish, equally parted, faintly tubercled, 

 spiral threads, the inmost of which is most distinctly tubercled, and defines the umbilical 

 depression. Longitudinals — the apical whorls, except the embryonic one, are crossed by 

 high, sharp, slightly oblique ribs ; but these on the later whorls break up into tubercles, 

 between which on the different rows there is a slight irregular connection by flattened 

 ridges, which are oblique, interrupted, and on the base sinuous. Besides these, the surface 

 is roughened by minute wavy irregular lines of growth. Colour white, with a translucent 

 layer of porcellanous glaze over brilliant pearly nacre. Spire high. Apex small, flattened, 

 with the minute inflated 1^ embryonic whorl rising a little exserted on one side. Whorls 

 7, projecting out squarely below the suture, flattened in the middle, protuberant at the 

 second row of tubercles, and slightly contracted above the carina; at the carina sharply 

 angulated. The base, which is flatly rounded, has a narrow flattish margin, and in the 

 middle a slight umbilical depression, in the centre of which is a minute umbilical hole 

 almost covered by the pillar-lip. Suture linear. Mouth scarcely oblique, and very slightly 

 inclined out from the axial line, squarish, but rounded on the base and at the angles, 

 a little broader than high, nacreous within. Outer lip not thin, with a slight callus just 

 within it ; it is slightly sinuated on the base at the outer corner. Pillar-lip, on leaving 

 the body, bends over very flatly so as to cover the umbilicus, after which it curves round 

 to the left ; it has a very blunt tubercle in the middle, is a little reverted, and has a very 

 slight furrow behind it. Umbilicus a small open depression leading into a minute central 

 pore. The slopes of the depression are obliquely scored by the tubercles of the central 

 basal thread. H. 0"22 in. B. 0-16, least 0-15. Penultimate whorl, 0-05. Mouth, 

 height 0-06, breadth 0*07. 



This beautiful little shell offers some rather perplexing features ; for the curves of growth on the 

 base indicate a slight sinus toward its outer edge, which, indeed, is shown in the actual mouth- 

 edge, — a peculiarity suggestive of the genus Basilissa ; but there is not seldom in the Trochidas 



