HELICIDA. 17 
anteriorly, convex beneath, compressed around a moderate, funnel- 
shaped umbilicus ; aperture very oblique, irregular, transversely oblong, 
laterally spread out; peristome simple, superior margin depressed, 
dilated in front, columellar margin shortly reflexed. 
Diam., greatest, ‘95; least, "79 ; height, -43. (Pfr.) 
Nelson. Bay of Islands. 
Sub-Genus, Thalassta— Albers. 
Shell scarcely perforated, orbicularly conoidal, thin, pellucid ; whorls 
5-6, slowly increasing, the last angulated or carinated, the base at the 
perforation impressed ; aperture diagonal or slightly oblique, more or 
less angularly lunar; peristome simple, sharp, columellar margin some- 
what reflected. 
A. Shell trochiform. 
a. Umbilicus narrow. 
H. regularis, Pfeffer; P.Z.S., 1854, p. 50; ILH.V,, vol. 4, p. 
33; vol. 5, p. 86, Vo. 277; Reeve, Conch, Icon., f.1259. Shell perforated, 
the perforation partially covered, regularly coniforn, thin, very minutely 
striated, pellucid, viscously glossly, luteous, horny ; spire conical, rather 
acute ; suture scarcely impressed ; whorls 6, flattish, slowly increasing, 
the last not descending, acutely keeled, flattish beneath ; aperture 
diagonal, depressly-securiformed ; peristome simple, straight, margins 
remote, columellar margin dilated above, sub-adnate. - 
Diam, 125 height, *r2. (Pfr.) 
New Zealand. 
H. heldiana, Pfeifer; P.Z.S., 1851; ILH.V., vol. 3, p. 60; 
vol. 5, ~. 87, No. 279. Shell perforated, minute, trochiformed, thin, 
smooth, shining, fulvous-horny ; spire conical, rather obtuse; suture 
impressed ; whorls, 544, somewhat convex, the last keeled, not des- 
cending, slightly more convex beneath ; aperture slightly oblique, 
depressed, angularly lunar; peristome simple, straight, margins remote, 
columellar margin very shortly somewhat reflexed. 
Wiani., -eo\;iheisht.06.” | (Pir). 
New Zealand (Strange.) 
H. conella, Pfeffer, Mal. Blatt. viii., 1861, ~. 147 ; Mon. Hel. 
v., . 86. Shell sub-perforated, conoidal, carinated, thinnish, sub-acutely 
striated, minutely tessellated with horn colour and reddish markings ; 
spire convexly conoidal, with the apex rather acute; suture marginated 
at the periphery, and slightly convex at the base; aperture oblique, 
sub-angularly lunar ; peristome simple, straight, margins remote, briefly 
reflexed and arched over at the columellar margin. 
Diam, 18ssheight,:-rx. ';( Pir.) 
Kakepuku (Hochstetter.) 
H. poecilosticta, Pfeffer; P.Z.S., 1851; ALH.V,, vol. 3, p. 59; 
vol. 5, p. 89, Wo. 301 ; Reeve, f. 815. Shell perforated, trochiformed, 
thin, closely plaited, fulvous, rufous-spotted, diaphanous ; spire convexly- 
conical, apex rather acute; suture margined; whorls 5%, narrow, 
somewhat convex, the last keeled, not descending, flat beneath ; aperture 
