Propeamussium (Propeamussium) sp.

Plate 3, fig. 12

Material.

One internal mould of a single valve (SNSB-BSPG 2020 XCIX 12) and several small fragments from the lower member at Langza.

Description and remarks.

The internal mould of a fragment displays seven radial grooves, which correspond to internal ribs. The complete shell might have carried 8-9 ribs. These ribs end just before the ventral margin.

While the specimen undoubtedly can be referred to P. (Propeamussium), identification at the species level is impossible. The only Upper Jurassic species recognized by Johnson (1984) is P. (P.) nonarium (Quenstedt, 1858, p. 795, pl. 98, fig. 4), which is restricted to Europe and differs from the present specimen by relatively short internal ribs, which end well before the ventral margin.

Order Limida Moore, 1952