242 
The ornamentation begins to fade on the penultimate whorl, 
and the last whorl is smooth, except for a slight crenulation on 
the narrow shoulder, and faint spiral and axial lineation on the 
rest of the whorl. 
Aperture oblique, semilunate, narrowed above, and effuse 
below ; columella-lip very oblique, sinuate, distinctly produced, 
and thickened anteriorly ; outer lip arched, anteriorly dilated, 
thickened, but not varicose. 
Length, 6; width, 2°5 mm. 
Locality.—Tasmania (received from Mr. W. L. May). 
The only living’species to which R. semisculpta approximates 
sufficiently to necessitate detailed comparison is R. Antoni, 
Schwartz, from which it differs by gradated whorls, axial costa- 
tion more defined, and the nodulose cancellation hardly, or not at 
all, developed. 
SECTION ZEBINELLA. 
Rissoina elegantula, Azgas. 
References.—R. elegantula, Angas, P.Z.S., 1880, p. 417, t. 40, 
f. 10 ; Reeve, Conch. Icon. 
Tryon, Man. Conch. IX., t. 58, f. 13 (copied), p. 386. 
Tryon ‘thinks that R. elegantula will prove a younger state 
of this species [striata, Quoy & Gaimard]; it has eight whorls 
and is six mills, long.” Angas received his types from me, they 
were adults ; the species exhibits, however, variation in size, a 
macromorph before me measures 8 mills, and has eight whorls, 
and the axial lines are not obsolete on the body whorl; so that 
there is good reason, in the absence of actual comparison, for the 
opinion that R. elegantula is different from PR. striata. 
Distribution.—In South Australia it is found in St. Vincent 
and Spencer Gulfs, and extends westward to King George Sound. 
I have named it from Victorian and Tasmanian examples, and 
Mr. Henn has recorded it from New South Wales. 
SuBGENuS DIASTICTUS. 
Rissoina punetatissima, spec. nov. PI. vii., fig. 9. 
Shell conically pyramidal, somewhat thin and _ translucent 
(somewhat clouded at the suture and white at the aperture). 
Whorls five (apex unknown), slightly convex, spirally sulcated ; 
sulci closely punctated in a single series. The sulci increase in 
numbers with the growth of the shell; on the posterior whorls 
the two, three, or four antesutural ones are wider and deeper 
than the rest; about twelve sulcations on the penultimate whorl ; 
on the body whorl they are numerous, equally slender, and occupy 
the whole surface. Aperture auriform and somewhat explanulate ; 
