Ostrea sp. D

(Fig. 4 A-D)

MATERIAL. — 25 specimens (MDG/LBV/Lm-33.1 to –33.25).

OCCURRENCE. — Turonian of Gabon (this study).

DESCRIPTION

Shell is medium to large, inequivalve, inequilateral, elongated to elliptical shape in outline. LV is slightly inflated and RV flat. Umbo is small and opisthogyrate. Ligamental area is small. Anterior margin is curved. Posterior margin is straight or curved. Ventral margin evenly rounded. Attachment area is medium, depressed occupies the posterodorsal portion of the LV.Its ornamentation consists of numerous radial ribs which are crossing by concentric growth lamellae at irregular intervals. Ribs start at the umbonal area, occasionally carry ing small spines near ventral margin. RV is ornamented by concentric fine growth squamae.

REMARKS

Ostrea sp. D differs to Ostrea delettrei (Coquand 1869: 143, pl. 47, figs 1-6) in being smooth towards umbo and in having small space between concentric growth lamellae.