592 RET. E. BOOG WATSON ON THE 



narrow, horizontal, flat surface from the suture. All these 

 three lirations are ornamented with little tubercles or blunt 

 spines, which are strongest on the highest thread, and there 

 number about twenty-five on the body-whorl, on the second 

 thread there are about twenty-eight. The base, which is 

 rather flatly arched, has round the outside a flat surface hardly 

 deep enough to be called a furrow, defined on the inner side by 

 a clear narrow line, within which the curve of the base rises a 

 little and has some faint spirals. The edge of the umbilicus 

 is sharply defined by a fine line, outside of which is a broad 

 shallow furrow bordered externally by a slight spiral ; there 

 is another narrower furrow, the outer side of which is the 

 most projecting part of the base, but beyond this is rather 

 flat and has some obsolete spirals. On the upper whorls the 

 spirals are feeble and without tubercles, which only appear di- 

 stinctly on the fourth whorl. Longitudinals — the flexuous lines 

 of growth are very faint. Colour porcellanous when young and 

 fresh, but weathering to a chalky white, with a pearly nacre 

 below the thin surface and within the mouth, especially at the 

 outer upper corner. Spire conical, high, scalar. Apex very small 

 and sharp, flattened on the one side, and with the minute 

 1|- embryonic whorl projecting tumidly on the other. Whorls 

 7|, of gradual increase: the upper ones are rounded; the 

 later flat below the suture, then angulated, then flat on the 

 conical slope of the spire, and then very slightly constricted 

 above the carina, very slightly rounded on the base, with a flat 

 and slightly impressed, but sloping border round the outside, 

 sharply angulated at the umbilicus. Suture linear, but strongly 

 defined by the constriction and impressed angulation of the 

 shell at that point. Mouth perpendicular, nearly square. 

 Outer lip sharp and thin, not patulous, not descending. The 

 curves are very faintly indicated by the lines of growth, but 

 are similar to those described in S. formosa, Jeffi"., there being 

 three sinuses, one near the suture between the first and second 

 spinose thread, a second, very small but sharp, at the carina, 

 and a third toward the exterior of the base. Pillar-lip is j)atu- 

 lous and reverted, with a furrow behind it, twisted, with a 

 broad deep sinus above ; a strong twisted projecting tooth at 

 about two thirds of its length, below which is a smaller sinus 

 running out into a point at the extreme end of the pillar ; 

 this point corresponds to the umbilical carina. Umbilicus 

 more open than large, perpendicular and deep, being only slightly 



