Platyschisma vitrea n.sp.

PI. 3 figs 9-12

Description. Shell of 4\12 whorls, very small, low spired, naticiform, thin, shelled, with glossy surface, broadly phaneromphalous. Protoconch simple, smooth, rather flatly coiled, with no defined boundary between protoconch and teleoconch. Teleoconch whorls increasing in size gradually, whorl profile rounded; sutures moderately deep; surface glossy smooth with faint growth lines; base rounded but angled towards umbilicus; numerous revolving lirae and conspicuous growth lines within and near umbilicus; selenizone narrow just above periphery; aperture subcircular with columellar lip thin and reflexed; parietal inductura wanting, outer lip thin with a strongly developed sinus culminating just below periphery without generating a slit.

Types. Holotype (F78366) and 2 figured paratypes (F78367). There are 32 unfigured additional specimens (F78368) from the type locality.

Type locality. 150 m west of 'Marohn' homestead, on the Scone-Gundy roadside, 4 km south-west of Gundy, NSW (Locality 28).

Stratigraphic position. In bioclastic limestone, upper part of the Dangarfield Formation.

Geographic distribution. Type locality only.

Geological age. Late Tournaisian.

Etymology. Derived from the Latin vitrea meaning glossy, referring to the glossy surface of shell.

Remarks. This species is similar to Straparollus brevisn .sp. in having a low spired shell with a large umbilicus, but is very different in the shape of aperture and shell thickness. Platyschisma vitrea is characterised by having a thin glossy shell, suggesting that it may have been an algal dweller.