223 
periphery, the ribs having projecting points here, and the 
carina being curved between them; whorl excavately con- 
tracted below. Scarcely visible sublenticular longitudinal strie 
in upper part; rather less obsolete spiral striz ; these are 
more valid below the carina, where seven can be counted on the 
ventral aspect. Aperture narrow, elongately oblong. Outer lip 
varicosely thickened by a rib, margin thin, simple, and sharp, 
straight for four-sevenths of its length, between the angle and 
the carina, curved towards the notch in the lower two-sevenths, 
and containing a well marked sinus in the upper seventh, rather 
more than a_ semi-circle, not quite reaching to the suture. 
Columella strvight, slightly concave below, inner lp incon- 
spicuous. Ornament unicoloured dull stony-white. 
Length, 3°5 mm.; breadth, 1:25 mm. 
Habitat.—Dredge siftings (probably Backstairs Passage), deep 
water, two dead ( Verco). 
Diagnosis.—From D. telescopialis, nobis, by the pentagonal 
shape, the five ribs, and the absence of cancellation. 
Mitra Vineentiana, spec. nov. PI. viii., fig. 3. 
Shell, elongately-fusiform, moderately solid. Nucleus detached 
in all specimens, and earlier whorls corroded. Spire, eight 
whorls, slightly convex ; suture well marked, linear, minutely 
channelled. First three or four whorls longitudinally costate, 
coste gradually becoming obsolete, but may sometimes be traced 
to the next whorl, and may be represented by indistinct and 
irregular plice over the rest of the spire; spiral threadlets 
rounded and indistinct, about 12 in the penultimate whorl ; very 
minute sublenticular incremental longitudinal strie are also 
visible. 
Body-whorl uniformly very slightly convex; faintly marked 
close-set longitudinal striz, and numerous low, unequal rounded 
spiral threadlets, least marked over its centre. A very distinct 
spiral furrow starts just above the highest columallar plica, and 
winds round the dorsum of the base with two or three shallower 
ones behind it, and about four or five wrinkles in front of it. 
Aperture oblique, narrow, elongate-oval, contracted above, open- 
ing widely into the notch below. Outer lip uniformly curved, 
except for slight central straightening, simple, thin, sharp, 
smooth internally. Columella straight, very slightly excavated 
anteriorly ; plice four, well marked, intervals regularly narrowing 
anteriorly ; sometimes the elevated anterior margin of the columella 
exactly simulates a small fifth plica. Inner lip scarcely visible, 
except below the lowest plica, whence the callus stretches to the 
notch ; only in living specimens can the extent of the lip be 
recognised, and then only by the polished surface of the aper- 
P 
