Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 14. 1989. (Budapest, 1989)
LOCALITY The material was collected in an outcrop of Cape San Vigilio at Lake Garda near the village Torri del Benaco (North Italy, Southern Alps). A nearly 1 meter thick bed in the uppermost part of the oolitic limestone sequence yielded the rich fauna. Recently this bed has not been found, only several, some centimetres thin, condensed limestone horizons are fossiliferous in the same stratigraphie level. They are containing elements of VACEK's fauna. The section is a rather popular one, studied from point of views of stratigraphy and paleoecology by numerous geologists beside the cited authors. Here, we mention only some of the latest publications which give a revue of the older ones, too. STURANI (1964), in accordance with BUCKMAN (1910) and ARKELL (1956), states that VACEK's material has come from different stratigraphical levels from Uppermost Toarcian (Aalensis Zone) to Lowermost Bajocian {Discites Subzone of Sowerby Z.). STURANI gave also an accurate description of the sequence and suggested a subdivision of the "Oolite di S. Vigilio". BARBUJANI et al. (1986) took into consideration the Cape San Vigilio section in a remodelling of the sedimentary environment and the controlling geodinamic factors. In this paper, the Cape San Vigilio sequence was formally subdivided into three formations and, as a whole, it assumed the status of a group. From environmental point of view "the rebuilding of the partially drowned platform margin" is ascribed to the San Vigilio Oolite. In spite of the recent studies and the ever increasing knowledge of the lithological and sedimentological characteristics of the section, it was impossible to redefine the exact level(s) which provided VACEK's collection. The preservation of the gastropods confirms ARKELL's statement that they have come out of condensed limestone. The total lack of the well-dated Bajocian forms (CONTI and SZABÓ, in print) suggests that the gastropod-bearing levels could be below the "hardground" , recognised by STURANI (Sturani 1964, p. 8., fig. 2) and ascribed by BARBUJANI et al, (1986) to the San Vigilio Oolite Fm. within the San Vigilio Group. SYSTEMATIC S Order A R C H A E O G A S T R O P O D A Thiele, 1925 Superfamily Euomphalacea de Köninck, 1881 Family EUOMPHA LIDAE de Köninck, 1881 Genus Discohelix Dunker, 1848 Discohelix aff. dictyota Wendt, 1968 Plate I: 1-2. 1886. Discohelix cf. reticulata Stoliczka - VACEK, S. 108, Taf. XVIII, Fig. 11. aff. 1968. Discohelix (Discohelix) dictyota n. sp. - WENDT, p. 565, pi. 107, figs. 1-8; text-figs. 2A, 3E Material : a fragmentary specimen (1886/5/62). Description: The only specimen is a small, slightly excavated one. The visible part seems to be the spiral side but the embryonal shell is damaged, that is why the orientation remains uncertain. The peristome is not preserved so we can not decide whether it is an adult or a juvenile specimen. The cross-section of the whorls is trapezoidal with nearly equal width and height. There are definite carinae on both outer angulations of the whorls. Only collabral ornamentation is present between the two sutures, these are riblets, beginning immediately at the inner suture on a low, corrugated, longitudinal elevation. They end on the carinae of the outer angulations in tubercles, which are much stronger than those along the inner suture. The repetition of the riblets is not completely regular. A number of
