MOLLUSCA OP THE l CHALLENGES ' EXPEDITION". 105 



the deep suture aud by the inflated apex. From 0. (T.) hebes, 

 ~W., its sculpture and its apex distinguish it at once. 



5. CeRITHIUM MATUKENSE, n. sp. 



St. 173. July 24, 1874. Lat. 19° 9' 32"-35" S., long. 179° 41' 

 50"-55" E. 310-315 fins. Coral. 



Shell. — A tall, narrow, sharply-pointed cone, somewhat tumid 

 in the last whorl, with little sculpture, but with largish white 

 varices, and beautiful glossy brown spiral threads, speckled with 

 white on a dull translucent white ground. Sculpture. Longitudi- 

 nals — the upper whorls are thickly set with narrow, close, curved, 

 tubercled ribs, which run with a slight twist almost continuously 

 from whorl to whorl ; irregularly, but on nearly each whorl, one 

 of these ribs swells and broadens as a white varix. On the later 

 whorls the ribs are much less marked and the tubercles crowd 

 closely together on the spiral threads ; the varices, too, become 

 larger, and appear at the distance of \\ whorl ; the surface is also 

 thickly set with fine sharpish hair-like lines of growth. Spirals — 

 Besides one in the suture concealed by the succeeding whorl, 

 there are on the small apical whorls 3, but on the last 13 or 14 

 whorls there are 4 narrow well-defined rounded glossy spiral 

 threads ; on the last whorl, in its latter half, one or two more 

 narrower threads appear on the upperside of the whorl ; on the 

 base they are narrower and set more closely, and four or five 

 delicate ones ornament the pillar. On the last whorl especially 

 the upper spirals are studded with close-set small round tubercles. 

 The interstices are about three times as broad as the threads 

 themselves, and are delicately fretted with very fine spiral lines. 

 Colour a translucent white, dead towards the apex, with some 

 irregular brownish stains on the spire, dead-white varices, and 

 brilliant brown spiral threads spotted with white tubercles. Spire 

 tall, conical, and a little bent. Apex sharp but rounded. Whorls 

 20, of very slow and regular increase, scarcely convex, but the 

 last is a little tumid, flattened on the base, but not at all angulated, 

 and bisected by an exceptionally large varix. Suture linear, but 

 with a very slight impression. Mouth nearly semicircular, from 

 the great sweep of the outer lip, and the very slight relative con- 

 cavity of the whole inner lip from the upper corner of the mouth 

 to the point of the pillar; porcellanous within. At its upper 

 angle there is a narrow little corner formed by a slight contraction 

 of the lip towards the body, and by the elevation of the second 

 basal thread into a tooth by a porcellanous thickening at this 



LINN. JOTTRN. — ZOOLOGY, VOL. XV. 8 



