Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 79. (Budapest 1987)

Conti, M. A. ; Szabó, J.: Comparison of Bajocian gastropod faunas from the Bakony Mts. (Hungary) and Umbria (Italy)

served as basis for description of T. "tricarinata", and the adult stage, represented in the type specimen. The new finds show that the selenizone gradually shifts from the juvenile midwhorl position under the midwhorl in adult stage. It is important to comment on a character which was not mentioned in the earlier decriptions: a definite parietal callosity is present on the specimens which covers the basal lineation. Distribution — Somhegy, Humphriesianum and condensed Subfurcatum to Garantiana Zone; Case Canepine, Humphriesianum Zone. Family Pleurotomariidae SWAINSON. 1840 Laevitomaria gen. n. Type species: Laevitomaria problematica (SZABÓ, 1980) ( = Pyrgotrochusl problematicus), Diagnosis — Conical shell with slightly convex whorls, having nearly trapezoidal crosssection and outer face nearly parallel to axis in adult stage. Selenizone below midwhorl, its width about a sixth of distance between two neighbouring sutures; selenizone may be from hardly concave to rather convex. Base fiat and phaneromphalous; umbilicus rather wide. Ornament of spiral threads and grooves. Growth-lines prosocline above selenizone, opisthocline below it and opisthocyrt (falciform) on base. Basal ornament of spiral threads. Remarks — The conical shell is comparable with some similar forms of Pleurotomariidae

. The juvenile shell and the position of selenizone is similar to that of Pyrgotrochus, but the convexity of the whorls in this new genus gives a possibility to separate them. The position of the seienizone can serve as a basis for distinction between Conotomaria and Entemnotrochus versus Laevitomaria, respectively. Micadotrochus has a trochiform shape while Laevitomaria is conical; the longitudinal ornament of the previous one consists of obscurely nodosed cords but in the latter one thin, simple spiral lines and grooves are present. The most similar form is Leptomaria which differs in its juvenile shell and in the midwhorl position of the selenizone. The suture in Leptomaria runs above the periphery of the former whorl while they coincide in Laevitomaria. The shape of Laevitomaria is very near to that of Trochotomaria but the shape of the selenizone and the ornament of the adult shells separate these two genera. Namely: selenizone is bordered by two definite spiral cords only in Trochotomaria; the ornament is retiform in Trochotomaria but only spiral in Laevitomaria; the juvenile whorls of Trochotomaria are flat but these of Laevitomaria are somewhat convex. The assignement of Laevitomaria to Pleurotomariidae is temporary. In our opinion, Pleurotomariacea is badly in need of a revision ; it is necessary to form a systematics which will reflect the evolutionary relationships better than the existing, rather artificial families. This revision is suggested by some Tethyan finds which are transitional between some elements of Pleurotomariidae and Phymatopleuridae ; e. g. : Trochotomaria and Laevitomaria seem to belong to the same natural group (family), consisting of some genera from different actual families. Three species belong to this new genus: Laevitomaria problematica (SZABÓ, 1980), L. peripherialis (SZABÓ, 1980) (originally Pyrgotrochus) and L. ci. problematica ( = Trochotomaria ? cf. problematica in CONTI et MONARI, 1987 which is certainly a new species but the preservation of the specimens are not sufficient for a designation). Distribution — Umbria, Bajocian; Bakony, Pliensbachian and Bajocian. Family Acmaeidae CARPENTER, 1857 Scurriopsis (Scurriopsis) sp. 1987: Scurriopsis (Scurriopsis) sp. — CONTI & MONARI, p. 183, Pl. II. fig. 3. Remarks — The species, mentioned in the synonymy, occurred in the Bakony material, too, but the poor state of preservation prevented its correct description. As it was mentioned by CONTI & MONARI (1987), these forms certainly represent a new species but the apical shell portion is missing from all specimens thus right diagnosis cannot be given. Distribution — "Bivio Macerino",? Aalenian-Bajocian ('? condensed Murchisonae to Humphriesianum Zones — Humphriesianum Zone); Somhegy. Humphriesianum Zone.