Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 75. (Budapest 1983)
Szabó, J.: Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part V.: Supplement to Archaeogastropoda; Caenogastropoda
Suborder TROCHINA Cox et KNIGHT. 1960 Superfamily Trochacea RAFINESUQE, 1815 Family Trochidae RAFJNESQUE, 1815 Subfamily Proconulinae Cox. 1960 Genus PROCONULUS COSSMANN, 1918 Proconulus ibbetsoni (MORRIS et LYCETT, 1851) (Plate 1: figs 11-12) 1851 : Trochus Ibbetsoni MORRIS and LYCETT, p. 61, pi. 10, figs 4,4a. 1868: Trochus Ibbetsoni MORR. et LYC. — LAUBE, p. 12. pi. 3, fig. 1. 1950: Proconulus ibbetsoni (MORR. et LYC.) — Cox and ARKELL. p. 58. Measurements: H HL HA D W A Plate I: figs. 11-12. — 7 4.2 8 4.5 40-45 J Material — Three fragmentary specimens. Shape — The shell is dextral, high, slightly cyrtoconoid in outline and thick-walled. The whorl-surface is smooth, with the suture in a narrow groove. The periphery is rounded-angular, the surface of the base is hardly convex, without umbilicus. The aperture is circular, with prosocline peristome. The basal lip is widened, with a shallow depression just below the columella, which is bordered on the basal side by a tL C"-shaped angulation. Ornament — Beyond the prosocline growth lines, spiral ornamental elements appear only on the last whorl; these are faded grooves visible only with magnifier. Distribution •— England: Great Oolite; Poland (Balin): Upper Bathonian — Lower Callovian; Bakony, Somhegy: Humphriesianum to Parkinsoni Zones. Remarks — The shape and the construction of the aperture are strikingly similar to those of the genus Endianaulax (Ataphridae). Only the faded ornament suggests Proconulus. Proconulus? cf. galatensis (GEMMELLARO. M., 1911) (Plate 1 : fig. 6) cf. 1911 : Chemnitzia galatensis GEMMELLARO, M., p. 236, pi. 9, figs 17-18. Measurements: H HL HA D W A Plate I: fig. 6. — 5 3.5 5 — 50-35° Material — Two fragmentary (juvenile?) specimens. Shape — Dextral, cyrtoconoid form, with apparently pointed apex and thick shell. The number of whorls of somewhat convex or flat surface is relatively high, the suture between them appears as a narrow groove. The last whorl is higher than the previous ones, the periphery is rounded, the base is convex, without umbilicus. The peristome is slightly prosocline, rounded quadrate in outline, the outer lip becomes outwardly thin and the columellar lip bears a small callus. Ornament — Beyond the slightly prosocline growth lines transverse elements are visible only on the juvenile shell: these are tiny ribs between the sutures. Spiral sculpture is shown only on the base : spiral lines, which are stronger along the inner lip, fade out, then disappear at the periphery. Distribution — Bakony Mts., Sümeg: ?Upper Sinemurian. Remarks — The morphology of the shell suggests the genus Proconulus, except the last whorl, coiling of which differs significantly from that of the pervious ones. This feature, with associated similar shape, appears in the genus Ventricaria KOKEN, 1896 of uncertain systematical position. However, the here described forms lack the slightly tapering peristome, visible in the mentioned genus. This lack can be due to the juvenile state of the specimens — this is why the taxonomic arrangement is uncertain. The shape is near to that of the species Chemnitzia galatensis GEMM., M., but this form is described as a smooth species. Taking into consideration the weak ornament of the Sümeg specimens, it is possible that the lack of ornamentation is due to préservât ional causes.
