Natica Scopoli 1777

Natica sp. A

Figs 24X, 25 A–G

Material. MGUH 33154, MGUH 33155, MGUH 33156, ØSM.10042-88-e and ØSM.10042-104-b–c. An additional 47 specimens are found in the informally catalogued samples SH.104.A–B, SH.140.A, SH.142 (2 specimens), SH.157.A–B, SH.183.B, SH.198, SH.199, SH.200, SH.201, SH.202, SH.226, SH.228, SH.232, SH.249, SH.250, SH.274.B (3 specimens), SH.277, SH.281.A and E, SH.285.A, SH.311, SH.312, SH.367, SH.406.A–B, SH.448, SH.466, SH.467, SH.518.A, SR.297, SR.303.A–B, SR.312, SR.365.B, SR.380, SR.381, SR.402, SR.572.A–B, SR.573, SR.589.A–C, SR.623, SR.657.A, SR.668.B, SR.688, SO.129, SO.135.C and SO.192. Three specimens collected by A. Rosenkrantz at Skeldervig (13.07.1944 and August 1944) and Holtug Vig (August 1924) are located in the uncatalogued old collections at the Natural History Museum of Denmark.

Occurrence. The lower Danian Cerithium Limestone at Stevns Klint and contemporaneous ‘dead layer’ at Vokslev in Northern Jutland.

Description. Protoconch planispiral or very weakly heterostrophic at apex with close to 2 ½ flattened whorls; width approximately 0.85 mm. Embryonic shell 0.45 mm in width, corresponding to the initial ¾ of a whorl.

Teleoconch thick-shelled, globose with short spire, rounded whorls and impressed suture. Umbilicus moderately wide and deep with no separating ridge from the shell base. Aperture semicircular with straight, thickened inner lip ending in sharply angular abapical corner; height corresponding to around ¾ the shell height. Central columellar callus extension more or less completely absent. Parietal callus strong and wide, rectangular; the height corresponding to nearly half the aperture height.

Growth lines simple, straight and prosocline, turned slightly adaxially at suture. Some specimens have a subsutural furrow on at least the final protoconch whorl and initial teleoconch whorl.

Measurements. Largest specimen, MGUH 33154, 7.8 mm high and 7.9 mm wide, consisting of four whorls.

Remarks. The taxon varies somewhat in the convexity of the spire whorls and the relative spire height, sometimes making it resemble small specimens of Polinices sp. A described below. It is, though, recognizable on strength of the generally deep suture; the lower, more stepped spire and by the rectangular parietal callus.