MOLLITSCA OF THE * CHALLENGER ' EXPEDITION. 255 



bilicus it advances very prominently, with a strongly defined edge ; 

 below this pad it retreats sharply to the pillar, forming a nick on 

 the left side of the pillar ; below this it is again thickened and 

 expanded at the umbilical carination. Umbilicus funnel-shaped, 

 narrowed rather than defined by the umbilical carina ; it is half 

 concealed and within reduced to a mere pore by the heavy 

 twisted umbilical pad. H. 0*43. B. 0*45. Penultimate whorl, 

 height 0-11. Mouth, height 0-35, breadth 026. 



This species resembles JV". plrytelephas, Eve., from Australia; 

 but in that species the spire is not so much exserted, the umbi- 

 licus is open, circular, pervious, and spirally lirate. It is perhaps 

 nearest to N. plicatula, Nuttall, from China, but is much more 

 depressed, has the earlier whorls smaller, and though the umbilicus 

 is like it is much larger though more closed by the interior pad. 

 N~. Raynoldiana, Reel., has (P) the same kind of umbilicus, but the 

 front of the body-whorl is shorter and the apex is much finer. 



3. Natica pseustes, n. sp. 



July, 1874. Levuka, Fiji. Shallow. 



Shell. — Bounded, with no angulation in the whole contour, 

 obliquely depressedly globose, with spire scarcely projecting, thin, 

 smooth, glossy, porcellanous white, with a zone of large chestnut 

 irregular spots below the suture ; the umbilicus and pillar are 

 uniformly stained with the same colour. Sculpture. Longitudi- 

 nals — there are many delicate hair-like lines of growth, which are 

 strongest and most crowded near the suture and round the um- 

 bilicus. Spirals — there is a very faint appearance of rounded 

 threads and furrows, one of which below the suture is a little 

 stronger than the rest ; besides these the surface is densely, deli- 

 cately, sharply, microscopically scratched ; these scratches are 

 strongest on the upper part of the last whorl near the mouth, 

 w r here their intersection with the lines of growth produces a very 

 delicate sharp cross-hatching. The centre of the base has a 

 scarce perceptible carination, which becomes stronger just be- 

 hind the point of the pillar; within this carination is a strong but 

 shallow umbilical furrow, which deeply cuts in on the pillar, and 

 curves round the base of the strong pad which chokes up the 

 umbilicus. Colour semitransparent, porcellanous white, w T hich 

 becomes a dead white round the umbilicus and also in a broadish 

 band below the suture ; this white band is flecked with irregular 

 sharply defined, ruddy chestnut spots ; a stain of this colour in 



