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

disappear but angulations remain marked. Juvenile whorls covered by dense, sub-periodically repeating, weak growth ridges, corrugating also carinae. Ridges become flattened and more irregular both in strength and space on penultimate whorl, where carinae disappear; all changes gradual. At same growth stage, subregularly repeating nodes develop on outer angulations. Their strength, and distance between their pairs increasing with growth. Strong ridges connect nodes to adaxial suture more or less collabrally. Obscure spiral lines appear irregularly on all sides of last whorl. Remarks — The protoconch has dissolved therefore the exact nature of the sinistral coiling remains uncertain. If we regard the less concave side as spire, as it is done traditionally, this would be a sinistral species. The earliest visible whorl, which is probably the second one after the nucleus, seems slightly elevated in the deeper side therefore the false sinistral coiling is more probable. First of all, the only specimen of Discohelix hallstattensis n. sp. has to be compared to Discohelix ornata (HÖRNES, 1853), being similarly aged. The main differences are: the adult shell of Discohelix hallstattensis n. sp. has 1.5—2 times bigger diameter than Discohelix ornata, and the adult, nodosed last whorl develops in Discohelix hallstattensis n. sp. two whorls later than in Discohelix ornata; the form and arrangement of the nodes are also different; the nodes of Discohelix ornata are sitting on the carinae of the angulations while carinae are absent from the last whorl of Discohelix hallstattensis n. sp. GEMMELLARO (1911) published the most similar Discohelix specimens under the name "D. orbis", however, the Sicily (Galati) finds represent another (new) species (pers. obs.). These specimens have significandy different measurements from that of D. hallstattensis n. sp., wider, therefore lower number of whorls (11 in D. hallstattensis n. sp. and 7 in GEMMELLARO'S specimens with the same diameter). This species is also comparable to Discohelix ferox VON GÜMBEL, 1861 owing to the presence of nodosity but the adult size and number of whorls in D. hallstattensis n. sp. are larger. The same differences exist also in comparison with Discohelix lorioli GEMMELLARO, 1874. Distribution — Hallstatt, Hierlatz Alpe, Upper Sinemurian (Oxynotum Zone). Figure 4 — Discohelix hallstattensis n. sp., holotype. — A: less concave (spire?) side; B: "aperture" view; C: outer side view; D: more concave (umbilical?) side; all are in natural size; E: details of the ornament, x2.5. Discohelix excavata (REUSS, 1852) (Figure 5) 1852: Euomphalus excavatus REUSS — REUSS, p. 115, pi. 14, fig. 2. 1861: Discohelix excavata REUSS — STOLICZKA, p. 184, pi. 3, fig. 12. 1911 : Discohelix excavata REUSS — M. GEMMELLARO, p. 216, pi. 9, fig. 13. 1912: Discohelix excavata REUSS — TONI, p. 39, pi. 2, fig. 5. ? 1920: Discohelix excavata REUSS — DARESTE DE LA CHA

VANNE, p. 54, pi. 4, fig. 5. 1979: Discohelix excavata (REUSS, 1852) — SZABÓ, p. 22., pl. 1, fig. 5, (text)fig. 6d. Neotype — GBa 2008/69/34/1/1. Material — The type specimens of Euomphalus excavatus REUSS, 1852 seem to be lost just like those of Euomphalus orbis RLUSS, 1852, published at the same time. To fix the species interpretation, selection of a neotype is necessary. STOLICZKA's (1861) specimens fulfil all criteria (same locality, same strata and age), therefore provide a good occasion to accomplish this act. The need of fixation is well demonstrated by the fact that specimens of two different species have been also mixed to the content of boxes, labelled as Discohelix excavata in STOLICZKA's (1861) collections (see Discohelix sima n. sp. and Discohelix stolic^kai n. sp. below). The number of the studied specimens exceeds 100. Measurements neotype GBa 2008/69/34/1/2 H 9.5 **1Q HI HPW 6.8 8 D 22.4 22.7 W AS 263

c 262

c AU 116

e Shape — Dextral, discoidal, biconcave forms with deeper umbilical side. Nucleus and first whorl slightly raised on spiral side. Protoconch size can only be estimated as about 2 whorls without sculpture. Surface of whorls nearly flat on spiral and umbilical, but strongly convex on outer side. Angulations distinct and carinated from second whorl. Peristome seems not modified. Sculpture — Protoconch completely smooth;