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

length on the brachial one. The shell surface is smooth but there are some growth lines on some places. Internal characters: There were no adequate specimens available for serial sectioning due to the paucity of the material. Remarks: Liospiriferina acuta differs from the otherwise similar L. obtusa and L. sicula by its V-shaped fold. Furthermore, L. sicula usually attains greater size. Distribution: According to Aimeras (1964), L. acuta is Hettangian to Sinemurian in age. The species was reported from the Eastern Alps and the Bakony Mountains. Liospiriferina sylvia (GEMMELLARO, 1878) (Pl. Ill, Fig. 4; Text-fig. 19) 1878 Spiriferina sylvia n.sp. - Gemmellaro: p. 410, pi. 31, figs. 27-33. 1895 Spiriferina sylvia GEMMELLARO - Fucini: p. 158, pi. 6, figs. 11,14-17. 1937 Spiriferina sylvia GEMMELLARO - Ormós: p. 18, pl. 1, fig. 2. non 1895 Spiriferina sylvia GEMMELLARO - Fucini: p. 158, pi. 6, figs. 12-13. Material: 1 incomplete specimen. Dimensions (mm): Specimen M.91.18. (Text-fig. 19) length: 16.3, width: 21.5, thickness: 18.2. Description - External characters: Medium-sized shell, deltoidal in outline. The width is significantly greater than the length, the thickness is slightly greater than Text-fig. 19-Drawingof the length. The angle between the lateral Liospiriferina sylvia margins is about 110°. Biconvex form. The brachial valve is moderately convex while the pedicle valve is cone-shaped. The maximum width and the maximum convexity is situated at the umbo of brachial valve. The umbo of brachial valve is small and curved. The beak is small and acuminate. The ventral interarea is equilateral, triangular in outline, its surface is smooth. The width of interarea is half of the total length. The edges of interarea are rounded. The delthyrium occupies one-third of the interarea. The commissures are straight except for a small sulcus at the anterior margin. The width of sulcus is one-quarter of the total width but the depth of sulcus is only a few millimetres. Internal characters: There were no adequate specimens available for serial sectioning due to the paucity of the material. Remarks: Liospiriferina sylvia is very similar to L. darwini. They can be distinguished by the angle between the interarea and the commissures. This angle is 45° at L. sylvia and 80-85° at L. darwini. L. sylvia also resembles to L. statira. Their differences include a longitudinal fold on the pedicle valve (Gemmellaro 1874, pi. 10, fig. 3) and the slightly curved beak (Di Stefano 1891, pl. 1, fig. 5) of the latter species.