Homeomorphic gastropods from the Silurian of Norway, Estonia and Bohemia

Redescription of the gastropod Euomphalus undiferus Schmidt, 1858 from dir Upper Llandovery Rumba Formation of Estonia requires reinvestigation of the hitherto monotypic genus Kiaeromphalus Peel & Yochelson, 1976, originally described from the Rytteraker Formation of the Oslo Region. The Estonian K. undiferus and the Norwegian type species occur in similar depositional fac ies of Early Silurian age within the sedgwickii Graptolite Zone. The redesc ribed type specimen of Horologium kokeni Perner, 1907 from the late Siluria n (Ludlow) of Bohemia shows strong morphological convergence with the two B altic species, but Kiaeromphalus is distinguished by its lower rate of whor l expansion and less oblique aperture, Both genera were adapted to a sessil e life, possibly on a soft substratum.