1. Northern Prairie Wildlife Research Center, U.S. Department of the Interior, Fish and Wildlife Service, Bureau of Sport Fisheries and Wildlife (now U.S. Geological Survey, Biological Resources Division), 8711 37th Street, S.E., Jamestown, North Dakota 58401, USA
2. Present address: Prairie Veterinary Hospital, 1305 Business Loop East, Jamestown, North Dakota 58401, USA
3. Veterinary Services Diagnostic Laboratory (now National Veterinary Services Laboratories), U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, P.O. Box 844, Ames, Iowa 50010, USA
4. Present address: 1005 West 16th Street, Ames, Iowa 50010, USA