Sponges (Porifera) from Silurian strata on Gotland, Sweden

Bodily preserved sponges as well as isolated spicules are described from Silurian strata on Gotland, Sweden. Pyritized and calcareous specimens of Hindia sphaeroidalis Duncan, 1879 occur from the Lower Visby (Llandovery) to Hemse Formation (Ludlow). Among isolated spicules, octatines of Astraeospongium patina Roemer, 1861 are predominant. Calcareous spicules of Phobetractinia polymorpha Reif, 1968, Dvorcia mira Nekvasilova & Stemprokova, 1960, probably Reifelia diffissa Mostler, 1996, as well as isolated tricranoclones of Hindia, and spicules of unidentified taxa are reported for the first time.