Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 14. 1989. (Budapest, 1989)
Description: The specimen is a rather large, subglobose, shelly one with a short spire. The whorls are strongly convex with a narrow ramp, running along the suture; its outer rim is rounded. The suture itself runs in a deep furrow. In cross-section the whorls are axially ovate, almost circular with an angulation at the suture. The spiral ornament consists of two kinds of lines; between the pairs of the stronger ones (cords), 2-4 threads are visible. The cords are lacking from the ramp. The only observable transverse ornamental elements are the prosocline growth-lines. Remarks : VACEK employed the name Neritopsis philea d'Orbigny for this form, but there are some important differences why we have to make a correction. Neritopsis philea has transverse costae and small spines on them at the crossing points with the spiral cords, and these elements are absent from the San Vigilio specimen. For similar forms HUDLESTON (1894) suggested a "variety" of Neritopsis philea, named as " Abbas" . The mentioned differences are enough to regard the Bradford Abbas and the San Vigilio specimens as independent species. Because HUDLESTON's remarks are containing all the necessary informations, the name "abbas" is employable. The most comparable one of the similarly aged Neritopsis species is N. baugieriana d'Orbigny, but it bears regularly repeating transverse ridges along the suture on the last whorl, and only one Intersecting thread between the pairs of the cords. The juvenile shell is distinguishable from the small sized species Neritopsis subsulcosa (d'Orbigny) on the basis of the uniform spiral lineation on this latter one. Neritopsis benacensis Vacek, 1886 Plate II: 1-4. 1886. Neritopsis Benacensis nov. sp - VACEK, S. 107, Taf XVIII, Fig. 5. 1886. Neritopsis igilis de Gregorio - DE GREGORIO, p. 19, tav. XII, fig. 6-8, 12, 13. 1888. Necitopsis Benacensis Vacek - GIOLI, p. 8. 1899. Neritopsis Benacensis Vacek - GRECO, p. 124. Material: a relatively well-preserved specimen (1886/5/61) Measurements : H HL HA D W A 17 15.5 13 17 11 120° Description : The only specimen is a medium sized, very low spired one. Along the suture, there is a narrow, slightly convex ramp-like band, subangulate abaxially. The cross section of the whorls (and certainly the peristome) are elongated in a direction nearly parallel to axis. The embryonal shell is damaged, but it seems to be smooth. The post-nepionic shell is covered by alternating threads and lines, then, from a sudden onset, the last one and a half whorls are densely ribbed. These costae run from suture to suture (or to inner lip), repeating rather regularly and reflecting on the inner mould (so they are not varices). Remarks : Neritopsis species with similar sculpture were common during the Jurassic Period. Unfortunately, the number of their morphological characters are not too high, so it is not easy to give clear distinction of the species without comparison of specimens. For lack of UHLIG's originals (1878) which have been lost, we are not quite sure whether the following method to separate N. benacensis Vacek from N. haueri Uhlig is reliable or not: UHLIG's species is more depressed, aperture and cross section are nearly circular (ovate in N. benacensis), and uniform spiral lines cover the shell while threads and lines are alternating on N". benacensis. D'ORBIGNY's Neritopsis bajocensis has a similar shape, but its gradually weakening costae spread from the suture only to the periphery on the last whorl; the rounded angulation is present only on the species N. benacensis Vacek. Neritopsis elegantissima Homes and the related species (e. g. N. taramellii G. G. Gemmellaro, 1879, N. praeclar a Seguenza, 1895) are separable, besides the somewhat different shape, on the number and mainly on the existence of varices, which are not reflected on the inner mould.
