Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 73. (Budapest 1981)

Szabó, J.: Lower and Middle Jurassic Gastropods from the Bakony Mountains (Hungary). Part III.: Patellacea and Trochacea (Archaeogastropoda)

Measurements: H HL HA D WA Plate I: fig. 6 14 6 3.5 9.5 5 36° Material — More than forty specimens, mostly with strongly damaged shells. Shape — Dextral, high-conical, near the apex cyrtoconoid shell. The spire consists of numerous low whorls, the surface of these is slightly concave on the juvenile part and flat on the adult shell. In cross section, the inner space of the whorls is axially depressed elliptical. The base is flattened, medially excavated, anomphalous. The peristome is subquadral, its columellar lip bears a callus and a shallow excavation, moreover a tooth-like protrusion on its apertural side. Ornament — From the end of the third whorl, the spire and the base is covered by spiral threads, strength of these is rather variable, sometimes wholly missing, then only the growth lines give the ornamentation. These are strongly prosocline on the whorls and opisthocyrt on the base. Embryonal shape and ornament — The embryonal shape is cyrtoconoid. The protoconch consists of the spherical nucleus and about three whorls, which are convex in the beginning but later become concave. Half whorl after the nucleus, a carina appears on the middle of the whorls dissected by tiny nodes. This carina gradually removes to the lower suture to the end of embryonal shell, while the nodes disappear. Remarks — With the low whorls, this species is also similar to the Epulotrochus epulus

% (D'ORB.), especially those specimens without spiral ornament. However, its embryonal shell shows close relationship to Proconulus rimosus sp. n. This example suggests, that these genera are badly in need of a revision. Among the previously described species, "Calliostomd''' contextum G. SEG. (in. M. GEMMELLARO 1911) is most similar to P. epuliformis sp. n. However, its juvenile shell is not cyrtoconoid and the surface of the whorls is always flat. Distribution — Bakony Mts.

: Somhegy, Humphriesianum to Parkinsoni Zone. Proconulus rimosus sp. n. (Plate I: figs. 9-13) Holotype : Plate I: figs. 10-11. — Locus typicus: Bakonybél, Somhegy—Stratum typicum: horizontal fissure — filling limestone. — Derivatio nominis: rimosus (LAT.) = cracked; on a high number of the specimens unique cracked (or bored) shell portions are visible. — Diagnosis: trochiform; suture in a furrow, above it a carina is present, but the periphery of the adult shell is rounded; there is a shallow ridge on the base; ornament: spiral cords. Measurements: H HL HA D W A Plate I: fig. 10-11 10 6.5 11.5 7.5 57

J Material — Forty-five, mostly damaged shelly specimens, well completing each other. Shape —• Dextral, trochiform; the moderate high spire consisting of numerous whorls and has a slightly cyrtoconical outline. The surface of the whorls is somewhat convex on the juvenile and more convex on the adult shell. The height of this convexity is placed on the middle of the upper half of the whorls, so a narrow steep ramp runs below the suture. Above the suture, a strong carina is present, but the same is absent from the last half to one whorl of the adult specimens only. In crosssection, the whorls are subquadral, their inner space is orbicular. The base is convex, anomphalous, the peristome rather prosocline, next to its inner lip there is a narrow, elongated callus, columellar part of which is broader and gives rise to a low ridge on the basis. Ornament — The dominant ornamental elements of the adult shell are the longitudinal cords. Their number and strength increase during the ontogenesis to the last quarter or half whorl, where the growth lines become more marked, and the spiral lines disappear sometimes. The growth lines are prosocline on the surface of the volutions and double opisthocyrt on the base, because they are broken at the basal ridge. Embryonal shape and ornament — The nucleus is globular, smooth and slightly depressed in the first whorl. The surface of the whorls is convex in the beginning (1-1.5 whorls approx.), then it becomes flat (1.5-2 whorls) and thereafter the adult convex form is attained. A half coil after the nucleus, a spiral line appears on the midwhorl, on which small tubercles develope later. These become elongated transversally and shortly extend as riblets from suture to suture. From the onset of the riblets, the spiral line appearing first is one of the many longitudinal lines covering the whole surface of the volutions. The riblets of the flat whorls are weakly sigmoid and their ends are thicker than their middle section. The disappearance of these riblets is the boundary of the embryonal shell (but it may be at the onset of the riblets and in this case, the ribbed whorls, would be a juvenile part of the shell). The spiral ornament continues without interruption.