A late Paleocene fauna from shallow-water chemosynthesis-based ecosystems, Spitsbergen, Svalbard Author Hryniewicz, Krzysztof Author Amano, Kazutaka Author Bitner, Maria Aleksandra Author Hagström, Jonas Author Kiel, Steffen Author Klompmaker, Adiël A. Author Mörs, Thomas Author Robins, Cristina M. Author Kaim, Andrzej text Acta Palaeontologica Polonica 2019 2019-02-13 64 1 101 141 http://dx.doi.org/10.4202/app.00554.2018 journal article 10.4202/app.00554.2018 1732-2421 10980900 Genus Inoperna Conrad, 1875 Type species : Inoperna carolinensis Conrad, 1875 ; Campanian– Maastrichtian , Upper Cretaceous , southeastern USA . Remarks .— Inoperna Conrad, 1875 , is a poorly known mytilid bivalve genus reported from Mesozoic shallow-water deposits (e.g., Woods 1900 ; Stephenson 1923 ; Wade 1926 ; Cox and Arkell 1948 ; Hautmann 2001 ). Specimens assigned to Inoperna are elongate, thin-shelled mytiliform bivalves with subterminal umbones and characteristic ornament of commarginal corrugations, some of which merge into bundles of dorsal commarginal folds. Ten species, including Inoperna plenicostata ( Anderson, 1970 ) discussed herein, have been recorded previously ( Stenzel et al. 1957: 74 ; Vonderbank 1970 ). Mauricia Harris, 1919 , from the middle Eocene Cook Mountain Formation (Claiborne Group) in Texas , USA , is similar to Inoperna with respect to shell shape and ornament and could represent the same lineage ( Stenzel et al. 1957 ).