translate English to French: The molluscs are mainly concentrated in the lower two-thirds of the formation and are dominated by Valvata perdepressa, with abundant Valvata sincera, Probythinella lacustris, Amnicola limosa, Amnicola walkeri, Pleurocera acuta, Elimia livescens, Pisidium casertanum, Pisidium compressum, Pisidium fallax, and Sphaerium striatinum.
Les mollusques sont surtout abondants dans les deux-tiers inférieurs de la formation, où domine Valvata perdepressa, accompagnée de nombreux spécimens de Valvata sincera, Probythinella lacustris, Amnicola limosa, Amnicola walkeri, Pleurocera acuta, Elimia livescens, Pisidium casertanum, Pisidium compressum, Pisidium fallax et Sphaerium striatinum.