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)

Measurements: H L W Plate IV: figs. 6-7 5.5 16 14.5 Material — The majority of the available 20 specimens is well-preserved, including some internal moulds. Shape — Patelliform shell with bilateral symmetry. The shell starts in spiral coiling, thus the apex curves backwards slightly. The peristome is entire, ovate in shape, with pointed posterior part. The apex is subcentral in position. In lateral view the anterior part is convex, and the posterior part is hardly convex or straight. The shell is concave behind the apex and near the peristome of the adult specimens. The concentric undulation of the shell is well visible in apical view. This undulation is more conspicuous on the internal mould. The exhalant slit (trema) is situated upon an elliptic elevation, somewhat removed apically from midway between the peristome and the apex. Ornament — Most distinct elements are the nearly evenly spaced radial ribs. Only those two ribs along the elevation of the trema course with wider interspaces. The interspaces of the ribs arising from the apex are divided by weaker, later ribs, and also within the resulted interspaces weak threads appear near the peristome. The secondary grade of ribs is missing in the band between the two ribs along the exhalant slit, while the tertiary grade is represented with more (i.e. 3-3 or 4-4) elements. The growth-lines do not run side by side within the bands between the radial elements, and this results in a characteristic, cancellate sculpture. Remarks — The strongest ribs and the elevation bearing the exhalant slit are reflected also on the internal mould. Muscle scar was not visible. The previous descriptions do not mention the weak concentric undulation of the shell and the cancellate connections of the growth-lines. Disregarding this fact, the descriptions and the figures of STOLICZKA serve as good basis for identification of the available specimens. Distribution — Northern Limestone Alps: Hierlatz Limestone; Bakony Mts., Tűzköveshegy: Raricostatum Zone; Kericser: Upper Sinemurian to Stokesi Zone; Káváshegy: Davoei Zone. Genus EM ARGINULA LAMARCK, 1801 Subgenus EMARGINULA LAMARCK, 1801 Emarginula (Emarginula) vadanaei TONI, 1912 (Plate IV: figs. 10-11) 1912: Emarginula vadanaeilom — TONI, p. 38, pi. 2, figs. la-d. Measurements: H L W Plate IV: figs. 10-11 4 5.5 5 Material — Three specimens; one relatively well preserved and two poorly preserved examples. Shape — High, cap-shaped form. The apex curves backwards, overhanging even the line of the peristome. In transversal section the shell is flattened along the selenizone, but is convex in other parts. The selenizone is slightly elevated, with the slit extending about one-third of the shell height. The peristome is slightly ovate in shape. Ornament — The shell is ornamented with longitudinal and collabral ribs of nearly equal strength, resulting in a net-like sculpture. The interspaces of the stronger longitudinal ribs are divided by weaker ribs, and the selenizone is also subdivided transversely by lines of strength similar to these secondary elements. However, the lines on the selenizone are two- ot three-times denser than those collabral ribs along the selenizone. Additional transverse ornamental elements are the fine growth-lines. Remarks — The Bakony specimens resemble closely the species E. lepsiusi GEMM., 1879, but this latter shows fewer ribs, different dimensions and convex shell along the anal slit. The figures of TONI show transverse riblets weaker than the strongest longitudinal elements, while these are of equal strength in the Bakony specimens. Distribution — Southern Alps, Vedana: Middle Liassic; Bakony Mts., Kericser: Ibex to Davoei Zones; Lókúti domb: Davoei Zone. * * # Correction — Owing to a misinterpsetation "keel" was used instead of the correct morphological term "angulation" in Part I. The "keel" was not adopted in its true meaning.