Natica, Scopoli, 1777

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 93

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.

Figures

FIGURE 24. A. Tenagodus sp., Silicone cast of MGUH 33139. Tube diameter 5.6 mm. B–D. Campanile selandicum (Lundgren, 1867). B–C. Silicone cast of MGUH 33140. Width 11.4 mm. D. Silicone cast of MGUH 33141. Width 4.5 mm. E–F. Campanile sp. A. Silicone cast of MGUH 33142. Whorl height 2.1 mm. G. Campanile sp. B. Silicone cast of MGUH 33143. Height 4.2 mm. H–K. Metacerithium balticum (Ravn, 1902). H. Silicone cast of protoconch MGUH 33144. Width 0.45 mm. I. Silicone cast of MGUH 33145. Height 26.0 mm. J. Silicone cast of lectotype MGUH 91 figured by Ravn (1902, pl. I: 17). Width 11.7 mm. K. Silicone cast of MGUH 93, figured type for Cerithium sartorii Ravn, 1902. Height 7.1 mm. L. Dzikella? sp., Silicone cast of MGUH 33146. Width 6.0 mm. M–Q. Amaurellina ravni n. sp. M–N. Silicone cast of holotype MGUH 33147. Width 10.3 mm. O. The internal mould of paratype MGUH 33148. Width 13.2 mm. P. Paratype MGUH 33149, a mould with replaced shell. Height 12.8 mm. Q. Silicone cast of paratype MGUH 33150. Width of picture 3.0 mm. R. Trochocerithium sp., Silicone cast of MGUH 33151. Width 9.0 mm. S–W. Galericulus sp. S–T. Internal mould ØSM.10042-311. Length 5.8 mm. U. Internal mould MGUH 33152. Width 8.5 mm. V–W. Internal mould and external cast of MGUH 33153. Length 10.3 mm. Width of figure W 7.7 mm. X. Natica sp. A. Silicone cast of MGUH 33154. Width 7.9 mm.

FIGURE 25. A–G. Natica sp. A. A–B. Silicone cast of MGUH 33154. Width 7.9 mm. C–D. Silicone cast of MGUH 33155. Width 1.4 mm. E–G. Silicone cast of MGUH 33156. Width 2.1 mm. H–I. Natica sp. B. Silicone cast of MGUH 33157. Width 2.3 mm. J–N. Polinices sp. A. J–L. Silicone cast of MGUH 33158. Width 3.0 mm. M–N. Silicone cast of MGUH 33159. Width 5.2 mm. O–P. Polinices? sp. B. Silicone cast of MGUH 33160. Width 5.0 mm. Q–R. Rissoina? sp., Silicone cast of MGUH 33161. Width 0.6 mm. S–U. Zebinella selandica n. sp., Silicone cast of holotype MGUH 33162. Width 0.8 mm. Width of protoconch 0.55 mm. V. Alvania sp. A. Silicone cast of MGUH 33163. Width 1.2 mm.