The first Silurian sphinctozoan ever recorded is reported from the Canadian Arctic. The polysiphonate sphinctozoan, Rigbyspongia catenula n. gen., n. sp., is found associated with numerous anthaspidellid sponges. Diagnostic features of the new genus are its numerous axial siphons and vertical pillars within each chamber. Although it is structurally complex for a sphinctozoan of this age and is the only Silurian representative of the order, this new genus provides few clues to the still enigmatic problem of Paleozoic sphinctozoan phylogeny.

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