Diagnoza

The very large last coil hides the previous ones for the most part, the spire is small and low. The coils are convex. Adapically, an indistinct but relatively wide ramp is formed. The flank merges smoothly into the convex base. The sculpture is only preserved on the last coil. Numerous (at least 25) spiral ribs evenly cover the entire coil. Strongly prosocline axial ribs emanate from the adapical suture. They are strongest in the ramp area and fade out on the flank. They bump up the spiral ribs a little, particularly the spiral rib delimiting the ramp. The broad oval aperture is very large, broadly rounded abapically and only slightly narrowed adapically. The inner lip is widened callus.

Porównanie

Cossmann (1924) assigned the Laube’s type to N. guerrei Hébert & Eudes-Deslongchamps, 1860 and this assignment probably also applies to the specimen he depicted. Other authors (Hébert & Eudes-Deslongchamps 1860; Couffon 1919) described not only spiral ribs but also strong axial ribs of this species that extend from the adapical suture to the base. Cossmann (1924) noticed that the type series is very variable and, according to him, also includes variants without pronounced axial ribs.

Autekologia

Występowanie geograficzne

France and Poland (Balin only).

Zasięg czasowy

Mid Jurassic.

Materiały muzealne

Material from France and 2 specimens from Balin (NHMW 1853/0038/0094 and NHMW 1867/0008/0034).

Literatura

Cossmann, M. 1924. Extension dans les Deux-Sèvres de la faune du Callovien de Montreuil Bellay. Mémoires Société géologique et minéralogique de Bretagne, 1, 1–53.

Couffon, O. 1919. Le Callovien du Chalet,commune de Montreuil-Bellay (M.-&-L.).  245 pp. G. Grassin, Angers.

Gründel, J. 2012. Neubearbeitung der von Laube 1867 beschriebenen Gastropoden fauna aus dem mittleren Jura von Balin/Polen. Annalen des Naturhistorischen Museums in Wien. Serie A, 114, 193–288.

Hébert, M. & Eudes-Deslongchamps, E. 1860. Mémoire sur les fossiles de Montreuil-Bellay (Maine-et-Loire), 1re partie. Céphalopodes et Gastéropodes. Bulletin de le Société Linnéenne de Normandie, 5, 153–240.

Laube, G.C. 1867. Die Gastropoden des braunen Jura von Balin. Denkschriften der kaiserlichen Akademie der Wissenschaften, 28, 1–28.

d'Orbigny, A. D. 1852): Prodrome de Paléontologie stratigraphique universelle des animaux mollusques et rayonnes. Vol. III. 194 pp. Masson, Paris.