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

Distribution: According to Aimeras (1964), P. greppini is Hettangian to Sinemurian in age. Its occurrence in the Pliensbachian is uncertain. Beside the Bakony Mountains, this species is known from the Eastern Alps (Hierlatz) and the Southern Alps (Piemonte, Bergamo, South Tyrol, Venetian Alps). Prionorhynchia potyptycha (OPPEL, 1861) (Pl. I, Fig. 5; Text-figs. 7-8) 1861 Rhynchonella potyptycha n.sp. - Oppel: p. 544, pi. 12, fig. 4. 1884 Rhynchonella greppini OPPEL - Haas: p. 13, pi. 2, fig. 3. 1889 Rhynchonella potyptycha OPPEL - Geyer: p. 51, pi. 6, figs. 15-17. 1937 Rhynchonella potyptycha OPPEL - Ormós: p. 29, pl. 1, fig. 15. 1964 Rhynchonella ci. potyptycha OPPEL - Sacchi Vialli: p. 13, pi. 2, fig. 6. Material: 10 complete and 11 incomplete specimens. Dimensions (mm): Specimen M.91.08. (Text-fig. 7) length: 16.8, width: 20.3, thickness: 11.5. Description - External characters: Medium to large shell, subtriangular in outline. The sides of triangle are straight, the base is convex. The angle between the lateral margins is about 110°. The antero-lateral corners are very rounded. The width is significantly greater than the length while the thickness is two-thirds of the length. Biconvex form, the brachial valve is more Text-fig. 7 - Drawing of convex than the pedicle one. The maxi- Prionorhynchia potyptycha mum width is situated at the anterior third, the maximum convexity is at the posterior third. The beak is small and erect. The large and slightly depressed planareas are well demarcated by strong beak ridges on both valves. The lateral commissures are straight and slightly rise from the planareas. The lateral commissures run closer to the beak ridges of pedicle valve and divide the planareas in proportion of 2/3-1/3. The anterior commissure is straight or slightly uniplicate showing zig-zag deflections. The shell surface is costate, on each valve 18 to 20 sharp costae run straight to the anterior end without bifurcation. The cross-section of costae is high triangular. There is a weak capillation on the surface of planareas. internal characters (Text-fig. 8): The dental plates are parallel. The delthyrial cavity is rectangular in cross-section. The umbonal cavities are moderately wide and quite rounded in outline. No pedicle collar has been observed. The shell of brachial valve is quite thick at the socket. The socket is long, lentil-shaped and not crenulated. There is a small septalium. The teeth are aligned with the dental plates. No denticulum has been observed. The length of median septum is one-quarter of the total length and it disappears simultaneously with the crura. The crura are of prefalcifer type.