Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 16. 1993. (Budapest, 1993)
71889 Terebratula gregaria Suess - Geyer: p. 15, pl.2, figs. 20-24. 71895 Terebratula gregaria Suess - Fucini: p. 191, pl.7, Fig. 15. 1909 Terebratula subgregaria n.sp. - Dal Piaz: p. 6, pl. 1, fig. 3. Material: Szesztra-hegy (2) and Lókúti-domb (6). Dimensions (mm): Specimen M.93.10. (Text-fig. 9) length: 17.5, width: 13.5, thickness: 8.0. Description - External characters: Small to mediumsized shell, elliptical in outline. The length is larger than the width, while the thickness is about half of the length. The angle between the lateral margins is about 80°. Biconvex form, the pedicle valve is more convex than the brachial one. The maximum width and the maximum convexity are situated at the half of the length. The beak is Text-tie 9- Drawing of sma ^ anc * erect- The lateral commissures are straight, the Lobothyris 7 subgregaria anterior commissure is biplicate. The furrows run to the Szesztra-hegy ' two-third of the length. The depth of the furrows are 2-3 mm. The width of biplication is two-third of the total width. The width of the plica is smaller than the width of the furrow. Both valves are smooth. Internal characters (Text-fig. 10): A small pedicle collar has been observed. There are no dental plates, so the delthyrial cavity is circular in cross section. The hinge-teeth are long and narrow. There are two well-defined denticula. The socket is wide and not too deep. There is no median septum. The inner hinge plates are U-shaped in cross section. The crural processes are not well-developed. The transverse band has broken but it can be observed in a little shifted and tilted position: it seems to be low and not too wide. Remarks: On the basis of external characters the specimens are just like Rhaetina gregaria. However the internal characters refer to the genus Lobothyris. Dal Piaz (1909) described a Sinemurian biplicate species (T. subgregaria), which may be the same as the specimens of Bakony Mts. According to Dal Piaz (1909) his new species is very similar to Geyer's (1889) and Fucini's (1895) specimens described as Terebratula gregaria. There is also a biplicate form in the Pliensbachian ("Terebratula n schlosseri) described by Böse (1898). Besides these heterochronous homoeomorphs, Rhaetina gregaria has got a homoeochronous homoeomorph: Triadithyris gregariaeformis (Zugmayer) (Pearson 1977). RSileanu & Iordan (1964) figured a biplicate terebratulid ("Lobothyris gregaria") without systematic description or transverse serial sections (p. 17, pi. 6, fig. 33.). Distribution: According to Almeras (1964), L. ? subgregaria is Sinemurian in age. The specimens from the Bakony Mts. are Hettangian in age, thus extending the global range of this species. The species was reported from the Southern Alps and the Transdanubian Central Range. The occurrences in the Eastern Alps and the Northern Appennines are uncertain.
