Hypostomes in Cambrian agnostids from the Barrandian area (Czech Republic)

Remains of agnostid hypostomes are rare and have only been reported in about fifty specimens assigned to tenCambrian species. A large collection of several thousand specimens of a Cambrian skeletal fauna from the Barrandianarea includes articulated agnostids with in situ preserved hypostomes in two species from the Příbram–Jince Basin andin one species from the Skryje–Týřovice Basin. Unequivocal remains of hypostomes are described in Condylopygerex (Barrande, 1846), Peronopsis integra (Beyrich, 1845) and Onymagnostus hybridus (Brøgger, 1878). The materialprovides the first information on the hypostomal morphology in the superfamily Condylopygoidea Raymond, 1913and adds new data in two other Cambrian agnostid genera. The chemical composition and placement of agnostidhypostomes are briefly discussed.