Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 71. (Budapest 1979)

Szabó, J.: Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part I.: Euomphalidae (Archaeogastropoda)

Shape — Dextral, planispiral shell, with pentagonal shape in axial view. The keels are distinct in all growth-stages, with occasional weak carina. Owing to the periodical thickening of the peristome, inner and outer varices appear on the shell at intervals of about 72°. A type of inner varices appears at the place of the former peristomal inner lip, slightly behind the tip of the pentagon, an other type occurs at the place corresponding to the outer side of the outer lip, on the side bisector of the pentagon. The places of the inner varices correspond roughly to those of latter type, and reach from the keels to the suture and the quarter of the outer side. The peristome shows the two inner varices. Sculpture — From the fourth whorl the whole shell is covered by spiral lines, with crossing, and frequently interrupting growth-lines. The most distinct features are the exceptionally preserved, long hollow spines on the keels. These spines, when broken off, leave the characteristic parabolic nodes on the test. The surface of the fracture is usually visible. On the last whorl these nodes are arranged into triples around the tips of the pentagon. The first node of each triples forms a part of the outer varia, too. The next two nodes succeed with a similar interspace. The succeeding nodes appear on, and somewhat after the tip, respectively. The infillings of the scars of the broken spines begin with „parabolic growth-lines", which run suture-to-suture, and apparently cross the former growth-lines. On the juvenile whorls the nodes elongated transversally, without associated spines. Embryonal shape and sculpture — The nucleus is smooth, globular. It is followed by approximately 3 whorls with normal logarithmic spiral coiling, then the first deviation appears. About a half whorl after the nucleus onsets a spiral lineation, which endures on the next 1.5 to 2 whorls, then disappears and renews after a one-whorl interruption. Remarks •— The Bakony Mountains specimen with the preserved spines suggests to reinterpret the explanation of WENDT (1968) on the parabolic sculptural elements (see above). Distribution —Western Sicily, Aalenian — Middle Bajocian; Bakony Mountains: Somhegy, Humphriesianum to Garantiana Zone. References DARESTE DE LA CHAVANNE, J. (1930): Fossiles liassiques de la region Guelma. — Cart. Géol. I'Alg. ser. Pal., 8: GALÁCZ A. (1976): Bajocien (Middle Jurassic) sections from the Northern Bakony (Hungary). — Ann. Univ. Sei. Budapest., Sect. Geo I., 18: 177-191. GALÁCZ A. & VÖRÖS A. (1972): Jurassic history of the Bakony Mountains and interpretation of principal lithological phenomena. — Földt. Közi, 102: 122-135. GÉCZY B. (1971a): The Pliensbachian of the Bakony Mountains. — Acta Geol. Hung., 15: 117-125. GÉczY B. (1971b): The Pliensbachian of Kericser Hill, Bakony Mountains, Hungary. — Ann. Univ. Sei. Budapest, Sect. Geol, 14: 29-52. GÉCZY B. (1972a): Ammonite faunae from the Lower Jurassic standard profile at Lókút, Bakony Mountains, Hungary. — Ann. Univ. Sei. Budapest, Sect. Geol., 15: 47-76. GÉCZY B. (1972b): The Sinemurian in the Bakony Mountains. — Acta Geol. Hung., 16: 251-265. GÉCZY B. (1974): The Lower Jurassic ammonite faunas of the Southern Bakony (Transdanubia, Hungary). — Ann. Univ. Sei. Budapest, Sect. Geol., 17: 181-190. GÉCZY B. (1975): A Davoei Zóna a Bakony-hegységben. — Földt. Közi., 105: 419-428. GEMMELLARO, G.-G. (1874): Sopra alcune faune giuresi e liassiche de Sicilia. Studi paleontologici. III. Sopra i fossili délia zona con Terebratula aspasia Menegh. délia provincia de Palermo e di Trapani. — Giorn. Sei. nat. econ. Palermo, 10: 53-112. GEMMELLARO, G.-G. (1879): Sopra alcune faune giuresi e liasiche di Sicilia. Studi paleontolcgici. VII. Sui fossili del calcare cristallino délie Montagne del Casale e di Bellampo nella provincia di Palermo. — Giorn. Sei. nat. econ. Palermo, 13: 233-434. GEMMELLARO, M. (1911): Sui fossili degli strati a Terebratula Aspasia délia Contrada Rocche Rosse presso Galati (prov. di Messina) Cephalopodi (fine) — Gasteropodi. — Giorn. sei. nat., econ., 28: 203-242, Pl. 8-9. HAAS, O. (1912): Die Fauna des mittleren Lias von Ballino in Südtirol. I. Brachiopoden, Lamellibranchiaten und Gastropoden. — Beitr. Pal. Geol. Ost.-Hung., 25: 223-285, Pl. 20. HALLAM, A. (1972): Diversity and density characteristics of Pliensbachian-Toarcian molluscan and brachiopod faunas of the North Atlantic margins. — Lethaia, 5: 389-412. HAUER, F. (1853): Ueber die Gliederung der Trias-Lias- und Juragebilde in den nordöstlichen Alpen. — Jb. kk. geol. Reichs., 4: 715-784.