Cyclothyris difformis (Valenciennes in Lamarck, 1819). A–N. Five specimens (Gaspard coll.) from the Cenomanian of Normandy (Cap de la Hève, France). A–C. Dorsal (A), lateral (B), and anterior (C) views of a juvenile specimen MNHN.F.A67478 with a faintly rectimarginate anterior margin. D–F. Monoplicate juvenile/preadult specimen MNHN.F.A67479. G–I. Adult specimen MNHN.F.A67480 showing right-asymmetrical anterior commissure. J, K. Small adult specimen MNHN.F.A70585 showing left-asymmetrical anterior commissure. L–N. Scanned specimen MNHN.F.A59944 (for video and virtual transverse and longitudinal sections see online Appendices A–C). O–Q. Specimen IGR23222 (Néraudeau coll.) from the Early Cenomanian of Cadeuil (Charente-Maritime, France). Photographs: P. Loubry. Scale bars = 5 mm.