SCHISOMOPE. 63 



whorl carinatad in its latter half by the prominent upstanding 

 canal-ridge. Sculpture: Longitudinals there are fine, sharp, 

 pretty close-set, curved, radiating riblets, which are nearly equal 

 .above and below the canal ; between these in the furrows there are 

 fine lines. Spirals fully one-half of the last whorl is keeled by the 

 canal ridge, which forms a crest round the top of the whorl a little 

 within the periphery ; its outer edge is slightly overhanging, its 

 inner edge raised, a very little, the canal is narrow, and sinks between 

 these two edges ; it begins in a small oval and ends in a tumid 

 swelling, in which is a small oval hole, sharp-pointed in front. This 

 hole is not cut in the shell after that has been formed, but is devel- 

 oped along with it, the lines of growth conforming to the foramen. 

 The hole is continued within the shell by prominent lips, and a strong 

 little furrow is carried in the substance of the shell from the hole 

 to the edge of the outer lip. This furrow is marked outside by a 

 very slight ridge, but still more by the interruption of the riblets, 

 which curve sharply back, becoming at the same time very faint. 

 The whole surface is scored and the riblets serrated by sharp, fine, 

 remote threads, between each two of which towards the mouth a 

 weaker similar one appears. Spire quite flat. Apex very small, 

 slightly depressed. Whorls 3 to 3i, of very rapid increase ; above 

 they are barely convex, on the base they are tumid. Suture slightly 

 impressed. Mouth large, round, very oblique. Outer lip very 

 descending, flat above, well curved and patulous below ; it is con- 

 tinued, as in Lacuna, by a sharp keel, which runs straight up into 

 and encloses the umbilicus, but does not include its outer edge. 

 Inner lip short but strongish and defined on the body ; it very patulous- 

 ly overhangs the umbilicus, with a broad rounded furrow between 

 its sharp umbilical edge and its inner rounded border ; the sharp 

 umbilical edge runs straight down to join the outer lip on the base, 

 and the inner border runs down within the basal lip, flattening out 

 into a very slight callous. Alt. '055 in., diam. *083. ( Watson.) 



Off Culebra Island, West Indies, in 390 fms. 

 Sehismope tabulata, WATSON, Challenger Rep., Gasterop., p. 117, 

 t. 8, f. 7, 1886. 



S. LACUNIFORMIS Watson. PI. 68, figs. 9, 10. 



Shell obliquely, flatly globose, very finely striated longitudinally 

 and spirally, with rounded whorls, a very small, slightly raised apex, 

 barely impressed suture, very large gibbously round mouth, large 

 lacuniform umbilicus, and a mere dot of a fissure. Sculpture : the 



