Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 19. 2001. (Budapest, 2001)

Toarcian gastropods from the Gerecse Mts Genus ^Tretospira KOKEN, 1892/ Tretospira? sp. (Plate I: 17-18) Material — Two inner mould specimens. Measurements. H HL HP D WP AA AL 26.5 22 17.5 19.5 12.5 91° 85° Description — Littoriniform — bucciniform shell with rather low, gradate spire and convex whorls. Estimated number of whorls: 5-6, last half tending downwards with significant increase of suture angle. On last three whorls, sharp angulation visible that delimits narrow, almost horizontal ramp (sloping 5°—

15° abaxially). Ramp flattened, but feebly concave near peristome. Another, wider, flattened belt developes on last whorl below ramp and results widely subangulate periphery. Suture running somewhat below line of this latter angulation. Base convex, anomphalous and having low spiral elevation near columella. Aperture axially elongate; peristome probably continuous and having no other modification reflected on inner moulds than presence of rudimentary siphonal oudet that raises elevation on base, near inner lip. Columellar lip concave, probably having shallow, vertical furrow. Outer lip feebly prosocline and gently parasigmoidal below ramp. One inner mould reflects three low spiral carinae near to each other at periphery. Remarks — The material between infilling of two whorls preserved the thickness of the (duplicated) shell; it is one millimetre at the suturai corner of the peristome. Distribution — Vöröshíd quarry (Kis-Teke-hegy slope); Lower to Middle Toarcian. Purpuroidea? sp. (Plate I: 19) Material — A single specimen. Measurements. H HL HP D WP AA AL *26 22.5 *19 21 109° 101° Description — Subglobular shell of few (max. 5-6) convex (angular) whorls; spire low and gradate. Suture canaliculate; with narrow ramp below it that slightly convex on earlier whorls, but gradually changing into feebly concave on penultimate whorl. Sharp angulation delimits ramp abaxially. Below ramp two low elevations indicate further (less distinct) angulations or keels of shell. Lower one running just on periphery, upper one slighdy below midway between ramp angle and periphery. Inner mould of last whorl feebly concave between ramp angle and upper spiral elevation. Peristome not completely cleanable from matrix, visible lower part of outer lip prosocline, slighdy prosocyrt and showing siphonal notch. Remarks — Outward bending from the former growth surface on the inner mould along the siphonal outlet shows that this backward oriented notch is really trace of the original shell and not such truncation that formed during the fossilisation. The shape of the available specimen shows if it were a lower spired variety of Tretospira? sp. However, the differences in the spire angle, the number and position of the keels are enough to separate them on species level, but the siphonal notch is a diagnostic character on the generic level. Distribution — Kis-Gerecse quarry, Toarcian (Hildoceras bifrons Zone). ACKNOWLEDGEMENTS — The authors are indebted to Prof. Barnabás GÉCZY for donating some of the here described specimens and for the help with information on stratigraphy. We are thakful for the available specimens and some information about the localities that was collected by Dr. Géza CSÁSZÁR during the field works connected to OTKA T 025534 research topic. A. GALÁCZ'S contribution was supported by a project grant from the Ministry of Education (FKFP 0163/1999). J. SZABÓ's work on the Toarcian gastropods was granted by the Hungarian Scientific Research Fund (T 031 873). References BRÖSAMLEN, R. (1909): Beitrag zur Kentniss der Gastropoden des Schwäbischen Jura. — Palaeontograpbica, 56: 177—321, pis. 17—22. CONTI, M. A. & FISCHER, J.-C. (1984): La fauna à gastéropodes jurassiques moyen de Case Canepine (Umbria, Italie), sistématique, paléobiogéographie, paléoécologie. — Geologica Romána, 21: 125-183; Roma. CSÁSZÁR, G., GALÁCZ, A. & VÖRÖS, A. (1998): A gerecsei jura fácieskérdések, alpi analógiák. (Jurassic of the Gerecse Mountains, Hungary: facies and Alpine analogies.) — Földtani Közlöny, 128(2-3): 397-345, [in Hungarian with English abstract]. D'ORBIGNY, A. (1850-60): Paléontologie Française. Terrain jurassique II. Gastéropodes. — 622 pp., 451 pis.; Paris.