Ctenostreon sp.

Material.

One small fragment from the Ferruginous Oolite Formation near Chichim (SNSB-BSPG 2020 XCIX 21).

Description and remarks.

The very small fragment of a thick shell carries large, rounded, somewhat irregular radial ribs. The fragment can be differentiated from the genus Trichites by lacking the prismatic shell structure of the latter, and from large ribbed oysters such as Actinostreon marshii by the rounded nature of the ribs. The fragment is too small to warrant photographic documentation.

Infraclass Heteroconchia Hertwig, 1895

Order Trigoniida Dall, 1889