Platyschisma lingua n.sp.

PI. 4 figs 1-3

Description. Shell of about 5 whorls, very small, low spired, naticiform, thin, with spiral ornament, phaneromphalous. Protoconch simple, sharply pointed. Teleoconch with whorls increasing rapidly in size with whorl profile inflated and sutures moderately deep; ornamentation of closely spaced fine spiral lirae; base rounded, pseudoselenizone narrow above periphery; aperture with columellar lip slightly thickened and sinuous; parietal inductura wanting; outer lip with a moderately deep and narrow sinus culminating in a small and narrow slit or notch; anterior margin of the lip with prominent tongue-like siphonal extension.

Types. Holotype (F78369) and 2 figured paratypes (F78370 and F78371).

Type locality. The holotype is from 4 km south-east of 'Rangari' homestead on the Gunnedah-Barraba roadside, 34 km north-east of Gunnedah, NSW (Locality 18); 1 paratype is from Glenbawn (Locality 30) and the other paratype is from Swains Gully (Locality 25).

Stratigraphic position. In bioclastic limestone from the middle limestone lens in the Tulcumba Sandstone, from the lower part of the Namoi formation, and from the upper part of the Dangarfield Formation.

Geographic distribution. 'Rangari' to Glenbawn.

Geological age. Middle to late Toumaisian.

Etymology. Derived from the Latin lingua meaning tongue, referring to the shape of the anterior siphonal extension.

Remarks. This species is characterised by a large aperture and a long tongue-like anterior siphonal extension. It resembles Platyschisma vitrea n.sp. in having a low spire and in being smaller in size, but differs in having fine spiral lirae.