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

1953 Rhynchonella plicatissima var. rectemarginata VECCHIA - Rossi Ronchetti and Brena: p. 16, pl. 2, fig. 3. 1954 Rhynchonella plicatissima QUENSTEDT - Conti: p. 197, pl. 9, fig. 12. 1954 Rhynchonella plicatissima var. rectemarginata VECCHIA - Conti: p. 200, pi. 9, fig. 13. 1970 Calcirhynchia rectemarginata VECCHIA - Gaetani: p. 375, pi. 29, figs. 1-8. Material: 36 complete specimens. Dimensions (mm): Specimen M.91.06. (Text-fig. 4) length: 13.3, width: 13.5, thickness: 9.8. Description - External characters: Mediumsized shell, subtriangular in outline. The sides of triangle are straight, the base is convex. The angle between the lateral margins is about 85°. The ICAI ug. 1 — inlawing ui O Calcirhynchia ? plicatissima antero-lateral corners are rounded. The length and the width are nearly equal while the thickness is three-quarters of the length. Biconvex form, the convexity of the pedicle and brachial valves are equal. The maximum width is situated at the anterior third while the maximum convexity is at the posterior third. The beak is small and suberect. There are neither beak ridges nor planareas. The lateral commissures are straight to half of the length, after that show zig-zag deflections. The anterior commissure is uniplicate with a plica of very varied shape. On some specimens the plica is wide, slightly arched and low while on others it is narrow, high and trapezoidal. There are transitional forms between the two extremes. The entire 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 triangular. Internal characters (Text-fig. 5): The dental plates are parallel in the beginning. They are slightly arched therefore the cross-section of delthyrial cavity is oval. Later the dental plates are divergent and the delthyrial cavity becomes trapezoidal in cross-section. There is a narrow pedicle collar at early growth stage. The umbonal cavities are rounded in outline but not wide. The socket is long, narrow and not crenulated. The teeth are aligned with the long and not crenulated dental plates. There is a denticulum on its side. No septalium or median septum were observed. The crura are simple and short. They are of prefalcifer type. Remarks: Already Di Stefano (1886), Rothpietz (1886), and Geyer (1889) synonymized Rhynchonella hungarica Böckh, 1874 with R. plicatissima. In the original description Bockh (1874) also mentioned the similarity of the two species noting that the specimens from the Bakony Mountains are wider. It is here regarded to be within the range of intraspecific variability of Calcirhynchia plicatissima. Bockh (1874) referred to Quenstedt's original description stating that the costae of C. plicatissima are sometimes bifurcate. No bifurcation was found on specimens from Lókút Hill. The small individuals of Cirpa latifrons can easily be mistaken for wider specimens of Calcirhynchia plicatissima. Larger specimens of C. plicatissima can be easily separated as the beak of C. plicatissima is less prominent, the angle between the lateral margins is smaller, the specimens are narrower and more convex. Vecchia (1944) erected a new subspecies, R. plicatissima rectemarginata collected from Hettangian rocks. Later Gaetani (1970) raised it to spe-