73 
S.A. N'AT., VOL. XIV. 
May, 1933. By Brnund C. Cotton tuid F. k. Gndin-y. 
4 i]redgcd Bcachport 40 fathoms. Also Western Australia— Es- 
pcraiicCj Eliensbrook, jVlbany. (lypc locality — the seas of New 
iiolland). 
HELIACIDAE. 
Description as Jlcliacus, the only genus of the family here 
irecordcd. Distribution — W(n-ld-wide. tropical and subtropical. 
Dossil — Tertiary.. 
Animal possesses the essentia! features of Jrchitectomcidae. 
Heliacus d’Orbigny 1842. (= Torinui Cray 1840: 7ere- 
t'topoma Rochebriinc 1881). "Sun Shell.’ 'lurbinateiy ele- 
vated, or planorbifcjrm : protoconch paucispiral. .'^mooth; adult 
whorls rounded, granulated, spirally ribbed; outer lip and colu- 
mella simjtle; umbilicus moderate if) wide, perspective, its mar- 
gins slightly crenulated. Operculum horny, topically conically 
devated, externally multispiral, margined by projecting edges; 
Hitcrnal face smooth, bearing a spirally twisted median pnpjection. 
I'ypc — Solarhnn heherti Dcsliaycs. Ifefiaais differs from Jrcki- 
irctonica In having a nearly orbicular operculum, which is very 
cfinvex and marked with n spiral - ridge resembling a pagoda, 
"rhe operculigerous lobe on the font of the animal is cup-shaped 
when the operculum is removed, and the edges are elevated. 
The species affect deep tvatcr. and arc ver\- shy and sensitive 
•when observed. 
H, foveolatus 'i'atc 1893 (Torinia). 1^1. 1, fig. 2. ^'The 
Widely-umbilicated Sun Shell.” Turbinate, depressed, slightly 
convex; semitransparentwvhlte; penultimate whorl has four spiral 
riblets (of which one in the lower-third is the strongest), and 
slightly oblique axial tlireads, (nearly as stout :fs the largest of 
the spirals); the intersection of the spiral and axial threads pro- 
duce rhombic pits, within which are a few spiral striae; the 
largest spiral ribiet is granulated at the Intersections with the 
axials; body-whorl has a gcmmulatcd keel, the medial portion of 
t!ie upper surface has two gemmulated ribs, of about equal mag- 
nitude, at the suture there is a double smaller rib. and there is 
a finer one above the periphery; below the periphery are about 
five spiral equal-sized ribs, more or less gemiTudaied at the Inter- 
•scctions of axial sigmoidal threads; the umbilical wall lias about 
five flat threads crossed by lamella-like striae; whorls fou-. of 
rather slow increase; last whorl angulated at the periphery; base 
rounded; suture impressed; mouth quadrately rounded; umbilicus 
deep and tvide. Height 1.75. diam. 5, diam. of umbilicus 2.5 
mm. (Type locahu’ — Aldinga Bay and Semaphore). The con- 
spicuous oblique ribbing and very wide umbilicus distinguish it. 
