Streptacis sp.

PI. 22 figs 4-5

Description. Shell minute, very slender, high-spired, anomphalous. Protoconch of heterostrophic but initial portion missing. Teleoconch of about 9 whorls with only opisthocline growth lines; whorl profile symmetrically rounded, suture deep. Aperture oval, inner lip arcuate; outer lip thin, opisthocline.

Dimensions. Figured specimen (F78525) H 2.0 mm, W 0.5 mm, NW 10 .

Locality. Behind 'Kyndalyn' homestead, 10 km southwest of Somerton, NSW (Locality 24).

Stratigraphic position. In base of oolitic limestone in the Kyndalyn Mudstone Member of the Merlewood Formation.

Geological age. Middle or late Visean.

Remarks. This specimen resembles Streptacis elegantissima (Yoo) in shell shape and ornament, but differs in having finer collabral threads and a helical heterostrophic protoconch.