Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 26. 2008. (Budapest, 2008)

Shape — Shell fragment belongs to normally (not pentagonally) coiled shell of nearly bilateral symmetry. Two pairs of heavy nodes visible on outer angulations of short outermost (last?) whorl fragment, being fairly higher than wide. Sculpture — Mainly fine, and many subregularly repeating, riblet-like, strong growth-lines visible on spiral and umbilical sides, crossed by dense, thin spiral threads. Marked growth-lines and stronger spiral threads of nearly equal density

7 result network ornament on outer side. Remarks — The node-pairs of the outer angulations are much nearer to each-other than those of Pentagonodiscus reussii (HÖRNES, 1853) and their morphology is also different, similarly to the collabral and spiral ornamental elements. Therefore, the shell fragment can not be identified as P. reussii. The most similar morphology is visible on the last whorl of the available Discohelix ornata specimens; however, the reconstructed diameter of the fragment seems to belong to the last whorl of a shell with at least one whorl larger than the available, largest D. ornata specimens. There are the possibilities that the whorl fragment either shows the morphology of the latest growth phase in D. ornata that has not yet been observed in a more complete specimen, or it may be indicative of an unknown Discohelix species. Distribution — Hallstatt, Hierlatz Alpe, Hierlatz Limestone, Upper Sinemurian (Oxynotum Zone). Discohelix pseudomelia n. sp. (Figure 3: A-D, M-N) ?pars 1853: Euomphalus ornatus HÖRNES — HÖRNES in HAUER, p. 760. pars 1861 : Discohelix orbis REUSS — STOLICZKA, p. 182, pl. 3, fig. 9-10. Holotype — GBa 2008/69/32/3/1. Type locality — Hallstatt, Hierlatz Alpe. Type strata — Sinemurian (Oxynotum Zone) Hierlatz Limestone. Name — Referring the similarity to D. ornata (HÖRNES, 1853) Diagnosis — Medium size Discohelix species with trumpet-like peristome; strong carinae on both angulations, having rather sparse granules on the juvenile shell; granules strengthen as spiny nodes, becoming spirally elongated on last whorl; outer side concave along carinae but convex between concave belts. Material — Two specimens from "Discohelix orbis" inventory unit in STOLICZKA's (1861) "originals collection". Measurements holotype H HI HPW D *21.2 *7 AS 208

e AU 154° Shape — Dextral (?), depressed discoidal, nearly bilaterally symmetrical shell. Axial whorl section with feebly convex spiral, umbilical and outer sides; however, narrow concave belts also visible along both sides of marked carinae, running on outer angulations. Last whorl and adult aperture axially flattened (wider than high); aperture moderately broadened in all possible directions but remains quadrangular (traces observed on internal mould of last whorl). Peristome not preserved but outward tapering as shown by impression. Sculpture — Protoconch unknown; shell fragment of holotype on spiral (?) side show delicate growth lines and weak, subregularly repeating collabral ridges (second specimen show similar ornament on umbilical side, too). Carinae bear granules of density similar to that of ridges. Nodes become stronger, sparser and spirally elongated on last whorl. Undulating, fine spiral threads found only on, and close to carinae. Remarks — The adult size of D. pseudornata is much smaller than that of D. orbis (e. g. the diameter of shell is 18-24 mm in the earlier but exceeding 30 mm in the latter species). Quite exacdy: the adult stage is marked in D. pseudornata n. sp. by the development of the enlarged (trumpet like but angular) peristome on the last whorl. Feebly enlarged (probably mature) peristome was observable only on a fragment of a single specimen of D. orbis, having 42—44 mm reconstructed diameter. Dense, fine, spiral threads ornament D. orbis on the whole visible surface of the whorls but lacking from the spiral and umbilical sides of D. pseudornata n. sp., except the carinae of the outer angulations; they are present also on the outer side but only on, and closely alongside the keels. In Discohelix pseudornata n. sp., the carinae are sparsely granulated on the juvenile shell part but densely and subregularly undulating Ín D. orbis. The strong, sparse and spirally elongate nodes of the adult shell of D. pseudornata n. sp. never appear in D. orbis at similar diameter. In the arrangement of the spiral lines and the sparsity of the granulation on the juvenile keels, D. pseudornata n. sp. is similar to D. calculiformis DUNKER, 1847, but this latter species has significandy larger shells without any trace of comparable peristome modification and the coarser nodes of the adult D. pseudornata n. sp. Most important difference from D. ornata is in the geometry of the whorl cross-section. It is elongate parallel to the coiling axis in D. ornata, but flattened in the same direction in D. pseudornata n. sp. The carinae of the outer angulations limit an evenly arched, convex outer side in D. ornata, but a concave belt accompanies both carinae on the outer side in D. pseudornata n. sp. with a narrow convex belt between them. The strong nodes of the last whorl are restricted onto the carinae in D. pseudornata n. sp. but they extend as weakening ridges towards the coiling axis in D. ornata. D. pseudornata n. sp. seems to be