Plagiostoma? sp. B

Plate 4, fig. 6

Material.

A fragmented left internal mould with remains of the inner shell layer from the Ferruginous Oolite Formation near Zangla (SNSB-BSPG 2020 XCIX 36).

Description and remarks.

As the ventral part of the specimen is missing, its outline remains unknown, but most likely was obliquely triangular-ovate. The hinge line is short and straight, the umbo orthogyrate, the posterior auricle distinctly set off from the flank. The shell surface is ornamented with indistinct remnants of radial ribs. It differs from Plagiostoma ? sp. A in outline and style of ribbing. The few features that can be observed all support the placement of the specimen in Plagiostoma or a related genus.