80 RISSOIDE. 
FAMILY—RISSOID-. 
Inner lateral teeth very broad ; the apices incurved, lobed ; outer 
laterals dissimilar, all with denticulated apices. Rostrum more or less 
adnate below to the fore-part of the foot ; tentacles setaceous, with the 
eyes on bulgings at their outer bases ; neck lobes none; foot angulated 
in front, acuminate behind; operculigerous lobe with developed lateral 
expansions, and usually furnished with a caudal tentacular filament ; 
operculum horny, sub-spiral. Shell generally white, spiral, more or less 
turreted ; aperture usually simple in front. 
Genus, RISSOINA—D’Orbigny. 
Operculum semi-lunar, sub-spiral ; muscular impression longitudinal, 
with an elongated process before it. Shell turreted, mbbed or cancel- 
lated; many whorled; spire acuminate; aperture ovate, effuse an- 
teriorly, slightly channelled in front; outer lip anteriorly dilated, 
thickened internally. 
R. plicata, Hutton, CMM, p. 29. Elongated; whorls 6; 
spire whorls with two, body whorl with about five, spiral ribs ; spire and 
posterior part of body whorl transversely plicated; mouth round ; 
white. 
Length, ‘15 ; breadth, os. 
Stewart Island. 
R. rugulosa, Hutton, CMM, p. 28. Elongated; whorls 
seven, smooth, obscurely transversely ribbed ; aperture ovate ; white or 
yellowish-white. 
Length, 3; breadth, -r2. 
Stewart Island. Chatham Islands. 
R. purpurea, Hutton, CM.M., p. 29. Elongated; whorls 6, 
flat, not polished; sutures obscure; aperture round; spire purple or 
purplish-red, with a posterior spiral white,band ; body whorl yellowish, 
also with a posterior white band at the suture. 
Leneth,, "1, ;y breadth, ios. 
Stewart Island. 
R. subfusca, Hutton, CMM, p. 28. Whorls 5, flattened, 
smooth, but not polished ; aperture round; pale brown. 
Length, ‘12; breadth, ‘o5. 
Stewart Island. 
R. fasciata, Adams, P.Z.S., 1851, p. 264; Reeve, Conch. Ic, f. 
11g. Shell subulately-turreted, solid, dirty white, banded with reddish- 
brown ; whorls 8, rather convex, transversely finely striated, longitudi- 
nally plicated; plicee oblique, equal, rather distant ; aperture semi- 
ovate, sub-channelled in front ; lip sub-dilated (Adams.) 
New Zealand. (Sowerby.) Sydney. (Strange.) 
