A Review oe the Land Mollusca of Western Australia. 
41 
Shell di.seoi(lal, spire not sunken, whorls rounded, sutures deeply im- 
pressed, last whorl doscondiug a little, mouth subcircular, lip thin, columella 
not reflected, straight, umliilicus very wide. The apex is eoncentrically striate, 
the adult whorls closely finely ribbed, ribs about eighty in number, interstices 
striate. Coloration fawn. Breadth 2..') mm. ; height 1.5 mm. 
Luinodiscus sublestus Benson 1853. 
1853 — Helix snblesta Benson, Ann. Mag. Nat. Hist., Scr. 2, Vol. VI., p. 30, 
Jan. 1. Freemantle, Swan River, West Australia. 
rig’d. Reeve, Conch. Icon., Vol. VI., pi. 174, sp. 1177, Oct. 1853. 
Fig’d. Cox, Mon. Austr. Laud Shells, p. 1C, pi. XI., fig. 10, May, 1868. 
1930 — Charopa liedleyi Thiele, Die Fauna Siidwest Austr., Bd. W, lief 8, 
p. 587, pi. IV., fig. 67. Brunswick 
Benson naturally gave no details as to the protoeoneh features nor the 
number of ribs. It wa.s differentiated from ‘'H. luloidea, Forbes, by its 
narrower umbilicus, and the want of concavity in the spire; from H. cygnea 
by the flr.st mentioned feature, and the sculpture.” 
Thiele does not compare his new species with this, and generally there/ 
is agreement, the protoconch being described as spirally sculptured, its size 
being given at 3.75 mm. in breadth, 1. 8 mm. in height, with the umbilicus 
I mm. wide. 
Benson’s description is here given a.s the species needs fixation : “Shell 
rather broadly umbilicate, orbiculately depressed, above red horny, below 
horny, very minutely costulatdy striate above, rather flattened, sutures im- 
pressed, whorls four, the last a little depressed, rounded, aperture vertical, 
roundly lurate, peristome acute, umbilicus perspective. Diam. major 3, minor 
21 / 2 , axis 1 mill.” 
Specimens from the Swan River, collected by R. Helms, measure up to 
4 mm. in breadth by 2 mm. in height. These generally agree that the spire 
is flattened, but not depressed, the umbilicus wide, open, perspective, fully 
one-third the width of the base. The apex appears to be smooth but under 
a high power is seen to be finely concentrically striate, the adult sculpture 
of radial ridges shows between ninety and one hundred on the last whorl, the 
intestice.s being crossed by very fine eoueentrie threads, only discernible by 
a high power. 
iS])ecimons from Pe)ipermint Grove arc consistently smaller but other- 
wise there appears to be no definable distinction. 
Luinodiscus cygneus Benson 1853. 
Plate I., fig. 25. 
1853 — Helix cygnea Benson, Ann. Mag. Nat. Hist., Ser. 2, Vol. VI., p. 30, 
Jan. 1. Perth, Swan River, West Australia (Dr. J. F. Bacon). 
Fig’d. Reeve, Conch. Icon., Vol., VI L, pi. 174, sp. 1182, Oct. 1853. 
Pig’d. Cox, Aloti. Austr. Land Shells, p. 16, pi. 12, fig. 3. May, 1868. 
1930 — Charopa mprea Thiele, Die Fauna Sudwest Austr., Bd. V., lief 8, 
p. 587. Fremantle, S.W.A. 
Not Helix cuprea Cox 1868 nt supra. 
Contrariwise, Benson separated this from H. suhlesta by the more distant 
ribs, wider umbilicus, colour and larger size from 77. Tuloiclea, Forbes, of the 
eastern coast of Australia, by its more distant ribs and w'ant of concavity on 
the upper side. Diam. major 4, minor SVz, axis llj, mill. 
