Taxonomy from Fossilworks.org.Can also be found in Mazon Creek.
References:
F. R. Schram (1979): Worms of the Mississippian Bear Gulch Limestone of central Montana, USA. Transactions of the San Diego Society of Natural History. Volume 19, No 9, pp 107-120
A new interesting find from the British Columbia
http://vancouversun.com/pmn/news-pmn/canada-news-pmn/new-508-year-old-bristle-worm-found-at-burgess-shale-fossil-site-in-b-c/wcm/8c7c82f4-dd88-4bb4-ba99-e8cd44e9f176