MOLLUSCA OF THE ' CHALLENGEE ' EXPEDITION. 709 



Longitudinals — all the upper -whorls are crossed by strong straight 

 ribs, forming tubercles where they cross the spirals, and leaving 

 deep square hollows betvTcen. Only on the penultimate whorl 

 do these become oblique and feebler, till toward the mouth thc}^ 

 are narrow, weak, crowded and brolvcn. Besides these, the 

 whole surface is roughened with small, coarse, irregular lines of 

 growth. Colour dead white. Spire high and conical, but the 

 tumidity of the last whorl, especially towards tlie mouth, greatly 

 detracts from this ; it is slightly scalar. Apea: small. WJwrJs 

 6, of slow increase till the last, angular, projecting out squarely 

 from the suture, flattened on the contour, and contracted below 

 the carina ; but the last whorl is rounded, tumid, and, toward the 

 mouth, expanded. The base is rounded, but not inflated. Suture 

 very deep and strong, from the overhanging of the carina above 

 it. Mouth extremely oblique, perfectly round but for a slight 

 flatness across the body and an angulation at the junction of 

 outer lip and of the pillar-lip to the body ; pearly within. Outer 

 lip very slightly descending on its line of junction to the body- 

 whorl, then in its sweep rising a little : it is scarcely angulated 

 at the lower carina and at the point of the pillar, but it is a little 

 sinuated at that part ; it is thin on the edge, but is thickened 

 within by a pretty strong pearly callus and outside by a slight 

 rounded marginal varix. Pillar-lip is hollowed back into the 

 pillar in a sinus, and is sharply reverted, so as to leave a minute 

 but deep furrow behind it ; this reversion ceases just before it 

 reaches the umbilical thread, and forms a minute tooth at that 

 point. Jlmlilicus wide and pervious, but narrow^ed w^ithin ; its 

 slope is scored with minute sharp curved laminje, the remnants 

 of the old edges of the pillar-lip sinus. H. 0-18. B. 0-27, least 

 0'17. Penultimate whorl O'O^. Mouth, height O'l, breadth O'l. 



In general aspect this is very like T. {Margarita) gemmulosa^ 

 A. Ad., in the British Museum ; but that species has the spire 

 lower, the suture distinctly depressed, the sutural furrow is be- 

 set with close radiating stria?, the spiral threads are more nume- 

 rous and crowded, the pointed tubercles on these are more 

 frequent, and there is no varix on the outer lip. That last is a 

 feature which gives a great peculiarity to this species ; but the 

 thickening and the patulousness of the lip are not suflBcient to 

 connect it with Gaza. The distinct umbilicus and the absence 

 of a tooth narrowing the mouth separate it obviously from 

 Craspedotus. 



