MOLLUSCA OF THE 'CHALLENGEE' EXPEDITION!)', 695 



thin calcareous layer overlying the nacre. Spii-e high, a little 

 scalar. Apex small and sharp. Whorls 8, of regular increase, 

 a little rounded, angulated at the carina, rather tumid on the 

 base, with a wide umbilicus. Suttire angulated and well defined, 

 but a little filled up by the carina of the overlying whorl. Mouth 

 (apparently) perpendicular, semioval. Outer Up well rounded. 

 Pillar-lip) a little bent over on the umbilicus, and then advancing 

 rather straight towards the left, angulated and slightly toothed at 

 the point of the base where the umbilical beaded thread joins it. 

 TTmiilicus a wide deep funnel with a deep spiral staircase at the 

 junction of the whorls. H. OSS. B. 072, least 0-61. Penul- 

 timate whorl 0-19. Mouth, height 0-32, breadth 0-32. _ 



This beautiful species is unfortunately present in only one dead 

 and chipped specimen. It is more like T. maffus, L., than any 

 other species I know, but is obviously very different in all details 

 of form and sculpture. The name given to it is expressive of the 

 singular beauty of its sculpture. 



2. Tbochus (ZiziPHiNus) STiROPHOBUS, ^F. (ffrejpo^opos, keeled.) 

 St. 24. Mar. 25, 1873. Culebra, St. Thomas, Danish West 

 Indies. 390 f ras. Mud. 1 specimen. 



Shell. — Small, conical, scalar, inflated on the base ; whorls an- 

 gulated, with three strong carinas near the periphery, white over 

 nacre. Scitlpture. Spirals — at the periphery is a sharp flange-like 

 carina ; above this, about one third of the distance to the suture, 

 is a second, almost equally strong and prominent, which forms a 

 shoulder to the whorls. The space between this and the suture 

 is divided pretty equally by two threads, the lower of which is 

 feeble. On the upper whorls all of these are closely beaded, on 

 the last whorl only the two highest are so. Below the carina is 

 another remote strong thread, which meets the outer lip ; within 

 it is another, not quite so strong nor so distant, and occupying 

 the space from this to the middle are five flat close-set threads, 

 folloAVcd by three rather more separated and roughly beaded 

 threads, the inmost of which, like a twisted cable, forms a sort of 

 pillar with a chink between it and the sharp edge of the pillar- 

 lip, and advances into a small tooth at the angle where it joins 

 the outer lip on the base. Longitudinals — the whole surface is 

 roughened by rather coarse oblique lines of growth, which on the 

 upper whorls appear as oblique reticulating ribs. Colour white, 

 with a translucent calcareous layer over nacre. Spire rather 

 high, scalar. Apex a little flattened down and rounded, the 



