NOTES ON SOUTH AUSTRALIAN MARINE MOLLUSCA, 
WITH DESCRIPTIONS OF NEW SPECIES.—PART VII. 
By Jos. C Verco, M.D., Lond., F.R.C.S., Eng., Ete. 
Pratt XXITX. 
[Read September 3, 1907.] 
Ahacheortees a I’ a 
\Cyclostrema homalon, n. sp. Pl. xxix., figs. 
Shell small, thin, flatly depressed, of 44 whorls. Apical 
‘ whorls convex smooth. Spire whorls flat excavately sloping 
towards the upper suture, rounded towards the lower, with a 
spiral near the upper suture, which is well adpressed so as to 
simulate another spiral, and two near the lower suture. 
Body whorl large, with about seven spirals, the lowest form- 
ing a basal carina, starting where the inner lip joins the 
body whorl at its base, and ending at the outer third of the 
basal lip. Umbilicus large and perspective, with about ten 
spiral lire. There is a smooth area between the outermost 
and the basal carina. The aperture is quadrate, with round- 
ed angles, and lies in an oblique vertical plane. The labrum 
is excayated at a little distance from the suture, then pro- 
jects curvedly forwards, and then continuously retrocedes. 
The inner lip is applied to the base, so that the aperture is 
not quite circular or complete. Very fine crowded axial 
microscopic markings, which do not follow the sinuosities of 
the outer lip. 
Dim.—Largest diameter, 2°7 mm.; smallest, 2 mm.; 
height, 1 mm. 
Diagnosis.—C. harriette, Petterd, is closely allied, but 
has a less open umbilicus, and its labrum is not sinuous on 
the dorsum, but has a continuous convex curve; and the intra- 
umbilical spirals are much finer and more crowded. 
Variations.—One variety attains a size of 4°1 mm. in 
diameter, and is more solid. Its aperture is rounder; the 
umbilicus wider and more perspective, is radially wrinkled, 
and may not have so many spiral lire. There may be no 
spiral lira near the suture on the whorls, nor any elsewhere, 
or there may be several on the sides of the body-whorl. Some 
show the basal carina distinctly, others feebly, and others 
not at all; but the sinuosity of the lip is present and the 
miscroscopic radial markings. 
Locality.—Type, 62 fathoms north-west of Cape Borda; 
var., 130 fathoms, Cape Jaffa. 
