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)

Ornament — The most conspicuous sculptural element of the shell is the row of transverally elongated nodes on the lower rim of the whorls. These nodes end apically by gradual weakening, but downwards suddenly. Advancing to the peristome, these become rather like minute, sharp riblets, then pointing nodes on the penultimate whorl with one or two small ribs. All of the riblets reach one of the weaker tubercles occupying a position on the weak cord running immediately below the suture over the entire length of the shell. A few spiral lines are also observed under magnification together the variable prosocline growth lines. On the base, the latter are opisthocyrt, and crossed by spiral cords on the outer and some obscure lines in the middle parts. Remarks — The D. unicarinatus sp. n. and D. bicarinatus sp. n. (see below) are greatly similar to D. salinaria and D. lima from the Triassic (KOKEN'S species, 1897). However, they are nodose (ribbed) on their juvenile shells only. Distribution — Bakony Mts. : Somhegy, Subfurcatum to Garantiana Zone (condensed). Dimorphotectus bicarinatus sp. n. (Plate I: figs. 19-21) Holotypus : Plate I : figs. 20-21 — Locus typicus : Bakonybél, Somhegy—Stratum typicum : horizontal fissure

—filling limestone

—Derivatio nominis: bicarinatus = with two carina (on the periphery of the last whorl) — Diagnosis: high spire; bicarinate periphery; parietal callus; transversally elongated, rib-like nodes on the juvenile shell; low suture to suture ribs on the last whorl of the adult shell. Measurements: H HL HA D W A Plate I : figs. 20-21 6.3 4.5 8 5.5 24° PAHKINSONI 1 BAJOCIAN GARANTIANA 1 J I I i I I I l BAJOCIAN SUBFURCATUM ! I I I 1 I I I i HUMPHRIESIANUM i I I S P 1 N A T U M l ! MARGARITATUS l I PLIENSBACHIAN S T O K E S 1 I I PLIENSBACHIAN D A V 0 E 1 ! IBEX I ! I I J A M E S O N 1 I i I 1 RARICOSTATUM I i I \ UPPER SINEMU RIAN I i I \ UPPER SINEMU RIAN I i I ! \ i 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 14 1 s 1 6 17 1 8 Fig. 1. Stratigraphie distribution of the species in the Bakony Mts.: 1 = Pseudorhytidopilus sp., 2 = Proconulus epuloides sp. n., 3 = Proconulus scherinus (G. G. GEMM.), 4 = Proconulus epuliformis sp. n., 5 = Proconulus rimosus sp. n., 6 = Muricotrochus aff. subluciensis (HUDL.), 7 = Dimorphotectus sp., 8 = Dimorphotectus unicarinatus sp. n., 9 — Dimorphotectus bicarinatus sp, n., 10= Anticonulus lateumbilicatus (D'ORB.), 11 = Eucycloscala acanthicum (UHLIG), 12 = Bakonyia planapex sp. n., 13 = Ataphrus folcoi (M. GEMM.), 14 = Trochopsidea latitabra (STOL.), 15 = Trochopsidea kondai sp. n., 16 = Adeorbisina lateumbilicata (UHLIG), 17 = Adeorbisina procera sp. n., 18 = Zircia zircensis sp. n.