122 KEY. E. BOOG WATSON ON THE 



whorl 19 rows of small, narrow, but longish, rounded, rather 

 coarse tubercles, parted by furrows, which are shallow, rather un- 

 equal, and fully broader than the ribs. There are over the whole 

 surface fine irregular lines of growth, which are, as usual, 

 strongest on the base. Spirals — on all but the first two whorls 

 there are three spiral threads, which rise into tubercles as they 

 cross the longitudinals ; they are parted by deep narrow furrows ; 

 of these three the two lower are strong, the upper of the two 

 beiug a little the stronger and more prominent. The third and 

 highest spiral is not materially smaller than the others, but is 

 much less prominent, the whole whorl being at this part con- 

 stricted. The suture lies immediately above this spiral. Beneath 

 the lower spiral the whorl is sharply constricted, and a very 

 minute plain spiral lies in the bottom of the furrow and imme- 

 diately above the suture ; this minute spiral is the edge of the 

 strongish spiral which encircles the base. Round the base of the 

 pillar is a minute sharp spiral thread, which runs round the back 

 into the columellar canal. There are microscopic spirals over 

 the whole surface. Colour pure translucent white. Spire is high 

 and narrow ; its outlines, which are a good deal interrupted by 

 the sutural constriction, are slightly convex. Apex, of 1 J whorls, 

 is tumid, bluntly rounded, a little oblique, and glossy white. 

 Whorls 9, rounded, contracted above and constricted below. 

 The base is rather truncate and rounded. Suture very minute, 

 but well indicated by the broad open furrow in which it lies. 

 Mouth oval, little pointed above, with a small well-rounded canal 

 at the pillar. Outer lip sharp, scarcely incurved above, not pro- 

 minent, but patulous below, angulated at the corner of the canal, 

 round which it is scarcely reverted. Pillar straight, prominent, 

 and pretty strong, with a sharp twisted edge at its point. Inner 

 lip a mere glaze on the body, but forming a thin distinct edge 

 along the length of the pillar. H. 0*17. B. 0057. Penulti- 

 mate whorl, height 0032. Mouth, length 0*039, breadth 0*025. 

 This species is more like Cerithium cinctum, W., and C. depaupe- 

 ratum, W., than any thing else I know. These are both Madeiran 

 species. Its whorls are much more rounded than in either of these. 

 The base is not produced into a rounded cone as in C. cinctum, but 

 is rather abruptly truncate and very slightly contracted ; it is 

 also plain, and has not the spiral threads which appear on these 

 two species. The contraction of the whorls into the suture 

 makes the outlines of the spire very different, and the apex 



