Sponge fauna of the Upper Silurian Read Bay Formation, Somerset Island, District of Franklin, Arctic Canada

An unusually diverse and well preserved sponge fauna occurs in the Upper Silurian Read Bay Formation on Somerset Island in the Canadian Arctic. New demosponges described and figured include: Haplistion cylindricum n. sp., H. minutum n. sp., H. creswelli n. sp., Eochaunactis radiata n. gen., n. sp., Haplistionella garnieri n. gen., n. sp., H. minitraba n. sp., Somersetella conicula n. gen., n. sp., S. digitata n. sp., and Finksella turbinata n. gen., n. sp. Eochaunactis and Haplistionella are included with Saccospongia Ulrich, 1889, in the new family, Saccospongiidae. In addition a coarsely silicified Hindia (?) sp. occurs in the collection. The brachiospongioid Pelicaspongia perforata n. sp. is the single hexactinellid species in the collection. Calcareous heteractinid sponges are represented in the collection only by a single polyactine and three octactine spicules. The sponge fauna occurs in bioherms and in the intermound beds of the formation.