The polychaetous annelids included in this report were collected largely by the Allan Hancock Pacific Expeditions to Lower California, western Mexico, western Central America, the Pacific side of Panama, Colombia, Ecuador, Peru, Cocos and Galapagos islands, and southern California north to San Francisco. A few specimens, indicated with accession numbers, enumerated at the end of the station list, are in the collections of The University of Southern California, and were collected from southern California.
A station list follows, including only those stations of the Allan Hancock Pacific Expeditions which were represented in the families investigated in this report. Under each are listed the species collected, for the families herein considered. New species or new names are preceded by an asterisk.