This is the third part of a continuing series on helminths reported in waterfowl (McDonald 1974, 1981). Coots and moorhens (in Family Rallidae, Order Gruiformes) are included with the Anatidae of Anseriformes. The goal of these studies i complete coverage of waterfowl helminths of the world, although the original incentive-inadequate knowledge of the parasites of North American waterfowl- is less true now. World coverage is desirable because the world distribution of the family, tribes, and even many species of waterfowl often results in world distribution of parasites.