Gastropods from the Cretaceous-Palaeogene boundary in Denmark Author Hansen, Thomas text Zootaxa 2019 2019-08-12 4654 1 1 196 journal article 26049 10.11646/zootaxa.4654.1.1 9ce1d103-9234-4fbe-9544-f1c294bb8783 1175-5326 3365803 CFD82CC0-3110-472E-972B-7ADC0C523A04 Streptochetus sp. A Figs 30 N–O Material. A nearly complete external mould, MGUH 33253, and two incomplete moulds from the uncatalogued old collections at the Natural History Museum of Denmark . The latter two are collected by A. Rosenkrantz at Kirkebraade (19.091927) and Skeldervig ( August 1944 ). Occurrence. Very rare in the Cerithium Limestone Member , where it has been found at Skeldervig and Højerup, Stevns Klint. Description. Protoconch conical with between 1 ½ and 2 smooth, convex whorls separated by deep suture; protoconch measuring 0.55 mm in width and 0.35 mm in height. Teleoconch spire slender with convex whorls separated by moderately deep suture; whorl height less than half the width. Aperture narrowly ovoid with concave, seemingly smooth columella and oblique and wide siphonal canal; height of aperture and siphonal canal corresponding to 45 % of shell height. Siphonal canal short, only half as long as aperture. Fissure or weak pseudoumbilicus present. Siphonal canal with rounded distal end. Teleoconch sculpture dominated by around eight moderately strong, convex and more or less orthogonal transverse ribs per whorl. Transverse ribs crossed by six fairly broad and flat spiral cords between sutures; transverse ribs highest at periphery, fading out toward sutures; not organized in axial rows. Spiral cords strongest at whorl periphery. Growth lines slightly sigmoid. Measurements. MGUH 33253 is 9.2 mm high and approximately 3.6 mm wide, consisting of protoconch and six teleoconch whorls. Remarks. It is not possible to verify whether this taxon carries teeth on the outer lip or not. According to Wenz (1943: p. 1264) the genus should be characterized by a slightly oblique protoconch and a sharply cut distal end of the siphonal canal. Neither feature is observed in the present taxon, which otherwise is well in accord with the diagnostic features of this genus.