20 . 
LAND f^HELLS. 
S.A. NAT., 
\()\.. XVin, No. 2. 
Key to Species. 
Shell small, apex smooth, sculpture weak but of varying 
strength, umbilicus of medium size 
arenicola TsiX.Q.~stabilis . 
Shell a little flatter, apex apparently smooth, umbilicus 
wider decresensis. 
Shell flattened, conical, apex boldly concentrically striate, 
sculpture very fine, subreticulate riddlei. 
Shell flattened, conical, apex smooth, sculpture coarse, 
umbilicus still wider retinodes, 
Paralaoma stabilis sp. nov. PI. I, fig. 12. 
The common species of Paralaoma has been regarded as 
morti Cox, the Sydney shell, but it is easily distinguished, and as 
there was a name arefiicola Tate available that was used in my 
Basic List. I could not trace the usage of a prior arenicola^ but 
have since found it used by Martens (Die Heliceen, (Albers), 
2nd ed., p.l20, 1861, for “Pfr. Mon. Hellc. viv., Vol. Ill, p.875, 
based on Helix polymorpha var. arenicola Lowe, Proc. Zool. Soc. 
(Lond.), 1854, p.l90, Mch. 16 1855), and therefore a new name 
must be introduced. Tate’s Helix arenicola (Proc. Linn. Soc. 
X.S.W., Vol. II, p.291, June 1878) was named from Holdfast 
Bay, Yorkes Peninsula, South Australia, but I am selecting a 
Port Lincoln specimen for my type. 
Shell very small, depressedly helicoid, thin, brown, apex 
■smooth, adult sculpture radial ribs rather distant and minute 
intervening radial striae but no cross sculpture, ribs becoming 
■obsolete towards the aperture. There is only a very faint sub- 
peripheral keel present, whorls otherwise three in number, round- 
ed, umbilicus open, wide about one third the diameter of the 
shell. Mouth subcircular, a little descending, a little broader 
than high, lips thin, columella straight, scarcely reflected. Major 
■diameter 2 mm., height 1.25 mm. Tate mentioned a transverse 
siriation, which suggests, his species was distinct, but there may 
be many species of small shells confused. 
Paralaoma decresensis sp. nov. PI. L fig. 9. 
Kangaroo Island specimens of Paralaoma differ from those 
of the mainland in being more depressed, umbilicus wider with 
the sculpture finer. The stronger ribs of the mainland form 
appear to be missing. Vlajor diameter 2.25 mm,, height 1.25 
mm. 
