Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 16. 1993. (Budapest, 1993)

internal characters: The internal characters were not studied due to the paucity of the material. Remarks: The specimens are slightly fragmentary, nevertheless they can be well identified with Zeilleria mutabilis. The Hettangian specimens are smaller than the average size of Z. mutabilis in Early Sinemurian of Lókúti-domb (Dulai 1992). Distribution: According to Aimeras (1964), Z. mutabilis is Sinemurian to Pliensbachian in age. According to (Vörös 1982) this species occurs in the Late Sinemurian and the Pliensbachian of the Bakony Mts. The species was reported from the Eastern Alps, the Southern Alps, the Northern Appennines, the West Carpathians and the Transdanubian Central Range. Zeilleria s p. 1. (Plate II: Fig. 5; Text-fig. 20) Material: Kőris-hegy (1). Dimensions (mm): Specimen M.93.16. (Text-fig. 20) length: 19.5, width: 13.0, thickness: 10.0. Description - External characters: Medium-sized shell, probably elliptical in outline. The length is much larger than the width and the thickness but the specimen is not complete. The angle between the lateral margins is about 75°. Biconvex form, the convexity of valves are equal. The maximum width and the maximum convexity are probably situated at half of the length. The beak is small, narrow and erect. There are two weak beak ridges on the pedicle valve running to one-third of the length. The lateral commissures are straight. Both valves are smooth. Internal characters: There were no adequate specimens available for serial sectioning due to the paucity of the material. Remarks: The only fragmentary specimen renders a more precise identification impossible. However it significantly differs from the other two Zeilleria in the outline and in the shape and size of beak. Text-iig. 20: Drawing of Zeilleria sp. 1, Kőris-hegy Zeilleria ? s p. 2. (Plate II: Fig. 6; Text-fig. 21) Material: Som-hegy (1). Dimensions (mm): Specimen M.93.17. (Text-fig. 21) length: 22.5, width: 16.6, thickness: 11.0. Description - External characters: Medium-sized shell, elongated pentagonal in outline. The two corners are quite rounded at the lateral margins, while the other two are slightly rounded at the anterior margin. The sides of pentagon are slightly convex. The length is greater than the width, while the thickness is half of the length. The angle between the lateral margins is about 80°. Biconvex form, the convexity of valves are equal. The maximum width and the maximum convexity are situated at half of the length. The beak is very small