Bellerophon (Bellerophon) swainsensis n.sp.

PI. 1 figs 5-8

Description. Shell small, subglobular, isostrophic, anomphalous. Protoconch concealed, seemingly minute, planispiral. Teleoconch whorls involute and with largest diameter of whorl slightly less than height of spire; ornament consisting of closely spaced transverse costae and narrow selenizone; transverse costae curved back into selenizone; selenizone marked by closely spaced short lunulae. Aperture broadly crescentic, lips without flare anteriorly or laterally, but flaring somewhat backward in the umbilical region; parietal inductura covering a quarter of the last whorl, with thickening in the umbilical region.

Types. Holotype (F78344) and 3 figured paratypes (F78345 -6). There are 20 unfigured additional specimens (F78347) from the type locality.

Type locality. About 250 m west of Babbinboon Lane, in Swains Gully, 15 km south-west of Somerton, NSW (Locality 25).

Stratigraphic position. In bioclastic limestone, 130 m above the base of the Namoi Formation.

Geographic distribution. Type locality only.

Geological age. Middle Tournaisian.

Etymology. Referring to the geographical name of Swains Gully, Babbinboon, NSW.

Remarks. This species resembles Belierophon (BeUerophon) kyndalynensis n.sp. in shell shape, but differs in having a much larger and globular form. It has a far narrower selenizone than Bellerophon (Belierophon) kyndalynensis .