Introduction begins: The purpose of the present report is to assemble the contributions to annelidan literature of the late Aaron Treadwell (1866-1947) during the 58 years (1891-1948) of his publications on the polychaetous annelids. The type specimens on which these studies are based are deposited largely in the American Museum of Natural History in New York City and in the United States National Museum in Washington, D.C. Through the generosity of the administration of the American Museum of Natural History it was possible to examine all the type collections that were deposited there, and those in the New York Zoological Society which are now also in the American Museum. Many of the types in the United States National Museum had been earlier examined by me at Washington, as indicated in the bibliographic citations. The lists below, therefore, include all the names erected by Treadwell and give such identities as are believed to be valid. Some indicated as not seen by me are here given to complete the lists.
