Homalopoma, Carpenter, 1864

Hansen, Thomas, 2019, Gastropods from the Cretaceous-Palaeogene boundary in Denmark, Zootaxa 4654 (1), pp. 1-196 : 76

Homalopoma sp.

Figs 22 O–P

Material. Specimen MGUH 33117 is a very fragmentary external and internal mould of the final 2 ½ whorls.

Occurrence. The lower Danian Cerithium Limestone Member at Skeldervig, Stevns Klint.

Description. Teleoconch fairly low conical; whorls highly convex, nearly round in cross-section, separated by shallow suture. Aperture round.

Teleoconch sculpture consisting of numerous weak and fine spiral bands, more or less equally developed on spire whorls as on base. A beaded spiral band numbering perhaps 50 weak beads on last whorl runs adjacent to adapical suture. Weaker beading may be seen on several more adapical spiral bands.

Measurements. Tube diameter of last whorl 6.3 mm. Whorl radius reaches at least 6.4 mm.

Remarks. The Danish taxon resembles somewhat the Palaeocene Homalopoma sp. 1 of Kollmann & Peel (1983: p. 30–31) from Greenland, but differs by the weak subsutural constriction of the whorls and the weakly beaded adapical spiral bands. It differs from the Campanian Homalopoma minimum ( Quintero & Revilla, 1966) from Spain by the finer spiral bands.

Figures

FIGURE 22. A. Phorcus sp., Silicone cast of MGUH 33109. Exposed width 2.2 mm. B–C. Stomatella sp., External mould of MGUH 33110. Figure B has been colour inverted and mirrored to show it in positive. Width 1.5 mm. D–F. Solariella sp. D–E. Silicone cast of MGUH 33111. Width 6.2 mm. F. Silicone cast of aperture of MGUH 33112. Width 5.95 mm. G–I. Skenea sp. G–H. Inner mould of MGUH 33113. Width 5.2 mm. I. Inner mould of MGUH 33114. Width 10.2 mm. J–K. Leucorhynchia sp., Silicone cast of MGUH 33115. Width 2.4 mm. L–N. Tectus? indecorus n. sp., L. Umbilical view of inner mould of paratype ØSM.10042-327-b. Width 19.7 mm. M–N. Silicone cast of holotype MGUH 33116. Width 1.7 mm. O–P. Homalopoma sp., Silicone cast and inner mould of MGUH 33117. Width 9.6, 6.9 mm respectively. Q. Calliomphalus (Calliomphalus) sp., Silicone cast of MGUH 33118. Width 3.1 mm. R–U. Arene jakobseni n. sp. R–T. Silicone cast of holotype MGUH 33119. Width 8.6 mm. U. Silicone cast of paratype MGUH 33120. Width of aperture 4.8 mm.