Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 15. 1992. (Budapest, 1992)

Remarks: Prionorhynchia potyptycha differs from the otherwise similar P. greppini by its denser costation and more robust appearance. The examined species is similar to P pseudopotyptycha described by Böckh (1874). P pseudopotyptycha is , however, smaller and the valves form a more acute angle at the anterior margin. Distribution: According to Aimeras (1964), P. potyptycha is Hettangian to Sinemurian in age. Vörös (1982) demonstrated that it ranges up to the Ibex Zone of the Early Pliensbachian in the Bakony Mountains. The species was reported from the Eastern Alps (Hierlatz), the Southern Alps (South Tyrol, Venetian Alps, Saltrio), the Tell Atlas and the Bakony Mountains. Prionorhynchia pseudopotyptycha (BÖCKH, 1874) (PL I, Fig. 6; Text-fig. 9) 187'4 Rhynchonella pseudopotyptycha n.sp. - Bockh: p. 141, pi. 4, figs. 7-8. 1943 Rhynchonella pseudopotyptycha BÖCKH - Vígh: p. 45, pi. 2, figs. 21-23. Material: 2 incomplete specimens. Dimensions (mm): Specimen M.91.09. (Text-fig. 9) length: 11.4, width: 14.3, thickness: 7.9. Description - External characters: Small to medium-sized shell, subtriangular in outline. The sides of triangle are straight, the base is convex. The angle between the lateral margins is about 95°. The antero-lateral corners are slightly rounded. The width is significantly greater than the length while the thickness slightly exceeds half of the length. Biconvex form, the brachial Text-fig. 9 - Drawing of valve is slightly more convex than the Prionorhynchia pseudopotyptycha pedicle one. The maximum width is situated at the anterior third while the maximum convexity is at the umbo of brachial valve. The beak is small and erect. The height of beak is small, the two urnbones are almost opposite of each other. There are two strong beak ridges on both valves, which run to two-thirds of the total length. The planareas are slightly concave. The lateral commissures are straight, do not rise from the planareas and run in the middle of them. The anterior commissure is straight showing zig-zag deflections. The shell surface is costate, on each valve 12 to 14 sharp costae run straight to the anterior end without bifurcation. The costae are stronger on the brachial valve than on the pedicle one. The cross-section of costae is triangular. There is a dense and fine capillation on the surface of planareas. Internal characters: There were no adequate specimens available for serial sectioning due to the paucity of the material. Remarks: Prionorhynchia pseudopotyptycha was first described by Böckh (1874) from the southern Bakony Mountains. This species is known only from Hungary. Several other Hungarian authors mentioned the occurrence of this