Introduction: "In this paper we summarize some additions to be made to, and some modifications in nomenclature to be made in, the Polychaeta Sedentaria of Western Canada resulting from work on collections made by ourselves and others during a number of years past.
Four new species (Aricidea longicornuta, Stylarioides negligens, Notomastus variegatus, Fabricia pacifica) and one new variety (Polydora ciliata var. spongicola), are described. Two species are recorded new to N. America (Aricia michaelseni, Aricidea jeffreysi), three (Euclymene zonalis, Trichobranchus glacialis, Polydora polybranchia) to the entire west coast, and seven (Boccardia proboscidea, Magelona pitelkai) Cirratulus cirratus, Isocirrus longiceps, Rhodine bitorquata, Nicolea zostericola, Chone ecaudata) to that of western Canada. The opportunity is taken to make some comments on certain species which have been recorded previously from western Canada and the definitions of two genera are emended. The types of the new species are in the author’s collection.