Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 72. (Budapest 1980)
Szabó, J.: Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part II.: Pleurotomariacea and Fissurellacea (Archaeogastropoda)
ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 72. Budapest 1980. Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary) Part IT. Pleurotomariacea and Fissurellacea (Archaeogastropoda) by J. SZABÓ, Budapest Abstract — Designations of a new genus: Cyclostomaria gen. n. and a new subgenus : Pleurotomaria (Anodomaria ) subgen. n. are given. The following new species are described : Worthenia ? superstes sp. n., Pleurotomaria (Andomaria ) anodosa sp. n., Leptomaria somhegyensis sp. n., Bathrotomaria mandokiisp. n., Pyrgotrochus periferialis sp. n., P. solus sp. n. and P.?problematicus sp. n. With 4 figures and 4 photoplates. Introduction — For the outlined description of the localities, see Part I of this series (SZABÓ 1979). The description there serves as a basis for the hereunder tabulated facies-dependence (Fig. 1) and stratigraphical distribution (Fig. 2) of the species. It should be mentioned, supplementarily to Fig. 1, that the species-numbers are bigger than figured data for the red crinoidal limestone of basinal facies, but these specimens are mainly undeterminable, corroded internal moulds. The occurrences in the basinal facies confine to thin, condensed layers overhanging directly the hard-grounds, and these layers generally appear as the lower parts of thicker, crinoidal, or cherty limestone beds. Different occurrences were recorded only in the cases of specimens of Pyrgotrochus periferialis and Cyclostomaria suessi. These possibly suggest a habitat on muddy substrate, a feature not indicated for the other forms. However, the fact, that the majority of the species shows preference to facies submarine heights, does not mean a general affinity for hard bottom recorded in the extant pelurotomariids (HICKMANN 1976). Some data suggest that upon these submarine heights muddy bottom-types were also represented, and it was espzcially true for the surroumdings of the heights, where the skeletal parts accumulated. It is also possible, that a part of the species inhabited this latter environment. On the classification of Pleurotomariidae According to the practice followed so far, the most useful order of the morphological characters in the classification of Pleurotomariidae is as follows: A) Shape of the whorl-section and surface of the whorls. — B) Position and width of the selenizone (or slit). — C) On the basis of the above two features, almost all genera of the family can be identified with certainty. On the other hand, the form of the periphery and the base make the majority of the remaining uncertainties resolvable. — D) The spire angle is not characteristic in itself, but the types of its ontogenetic changes (coeloconoid, cyrtoconoid) may characterize certain genera. — E) Ornament and umbilicus. These features are used in the generic separation of Cenozoic and Recent forms. This usage in the classification serves as a good basis for further subdivisioning of the genera having been designated with the above-mentioned features. The available material makes possible to solve some classification problems. On the basis of features mentioned above under item A, the family can be separated into the following four groups: Ann. Hist.-nat. Mus. Nat. Hung., 72, 1980 4 Természettudományi Múzeum Évkönyve 1980
