Hipponix, Defrance, 1819

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 104

Hipponix sp.

Figs 26 V–X

Material. MGUH 33178 and MGUH 33179, both internal moulds; the latter with fragments of shell preserved.

Occurrence. The lower Danian ‘dead layer’ in Dania Quarry, Northern Jutland.

Description. Shell fairly thin, limpet-shaped, with variable height; apex above or behind rear margin. Margin irregular, probably conforming to substrate surface, not crenulated within. Shell surface, if preserved, smooth.

Interior with very weak anteriorly opened horseshoe shaped muscle scar. Specimen MGUH 33179 additionally with weak axial ridge anteriorly, reaching 2/3 of the distance from apex out towards anterior margin, dividing a left and right attachment area.

Measurements. Largest specimen, MGUH 33178, 23.8 mm long at base, 19.5 mm wide and 16.0 mm high.

Remarks. The taxon may be conspecific with the Danian (?) Patella nov. sp. of Kaunhowen (1898: p. 15, pl. I: 3–4) from Holland. It appears to have been more thin-shelled than Hipponix dunkerianus Bosquet, 1848 as illustrated by Binkhorst (1861: p. 58, pl. IV: 12a–c) from the upper Maastrichtian of Limburg, the Netherlands.

Figures

FIGURE 26. A–B. Alvania sp. A. Silicone cast of MGUH 33164. Width 1.5 mm. C. Alvania sp. B. Silicone cast of MGUH 33165. Width 0.8 mm. D. Zebina sp., Wax cast of MGUH 33166. Width 0.9 mm. E–H. Ceratia rodvigensis n. sp. E–F. Silicone cast of holotype MGUH 33167. Width 0.8 mm. G–H. Silicone cast of paratype MGUH 33168. Width 0.9 mm. I–J. Ceratia? sp. I. Mould of MGUH 33169. Width 0.9 mm. J. Silicone cast of MGUH 33170. Height 1.1 mm. K. Anchura sp., Silicone cast of MGUH 33171. Width 8.6 mm. L–M. Columbellaria tuberculosa (Binkhorst, 1861). Silicone cast of ØSM.10042-202-a–c. Width 5.2 mm, height 5.9 mm. N. Tylostoma? sp., inner mould MGUH 33172. Width 19.9 mm. O–P. Cassidae genus et sp. indet. Silicone cast and internal mould of ØSM.10042-315-a–b and c, respectively. Width 9.2 and 8.6 respectively. Q–U. Sassia faxense Ravn, 1933. Q. Detail of apex of MGUH 33173. Width of protoconch 1.4 mm. R. Silicone cast of MGUH 33174. Width 6.0 mm. S. Silicone cast of MGUH 33175. Width 6.5 mm. T. Silicone cast of MGUH 33176. Width 7.8 mm. U. Silicone cast of MGUH 33177. Width 5.2 mm. V–X. Hipponix sp. V–W. Internal mould MGUH 33178. Length 23.8 mm, width 19.5 mm. X. Inner mould MGUH 33179. Width 19.1 mm. Y–Z. Eulima? danica Ravn, 1933. Y. Silicone cast of MGUH 33180. Width 2.5 mm. Z. Silicone cast of MGUH 33181. Width 2.0 mm. AE. Eulima? sp., Mould MGUH 33182. Width 1.3 mm.