730 STUDIES ON AUSTRALIAN MOLLUSCA, xii., 



D. ustulata Deshayes, from which it differs by being more 

 slender, and by fewer, wider-spaced ribs. 



Shell solid, clavate-fusiform. Colour uniform buif. Whorls 

 about fourteen. At two- thirds of the height of the whorl, a deep 

 groove appears on the interstices, but not on the ribs; this ascends 

 the spire, but is inconspicuous on the earlier whorls. Below the 

 groove, there are eight spiral threads. On the last whorl, these 

 continue to the snout and amount to about thirty. The ribs are 

 polished, well spaced, slightly curved, set obliquely, not con- 

 tinuous from whorl to whorl, vanishing on the base, about 

 twenty to a whorl, rather less on the earlier whorls. Length, 23; 

 breadth, 6 mm. 



Hab. — Trial Bay (type), C. Laseron ; Ballina, C. Hedley; 

 Caloundra, H. L. Kesteven. 



MiTRA VOLUCRA, sp.nOV. 



(Plate Ixxxiv., fig.84.) 



Shell small, solid, compact, ovate-fusiform. Colour purple-slate 

 or cinnamon, with a narrow pale peripheral band and a pale line 

 below the suture. Five whorls remaining in the decollate speci- 

 men studied. Suture channelled. The earlier whorls are sculp- 

 tured by fine close radial riblets developed on the periphery and 

 vanishing towards the suture. These disappear on the last 

 whorl, which is smooth; between the riblets run spiral threads. 

 Aperture elliptical, plaits four, decreasing anteriorly, canal short. 

 Length, 11; breadth, 5 mm. 



Hab. — Woolgoolga, N.S.W.; three beach- worn specimens col- 

 lected by Mr. Carl Laseron. 



This species is superficially like the Tasmanian M. vincta A. 

 Adams, but difiers by being more solid, by having the suture 

 canaliculate, and by the sculpture. 



MlTRA ACROMIALIS, Sp.nOV. 



(Plate Ixxxiv., fig. 85.) 



Shell ovate-fusiform, rather thin and light. Colour pale buff. 



Whorls six, including a smooth protoconch of a whorl and a half, 



spire gradate. Sculpture : perpendicular ribs widely spaced, 



about seventeen on the last whorl, diminishing and alternating 



