Dr. Anderson's volume is an extension of Hanson's work (White-Cheeked Geese) in four ways. (1) A detailed statistical analysis of Hanson's taxonomy highlighted by a search for intergrades; (2) A revision of Hanson's taxonomy based on the re-analysis; (3) An evolutionary scenario accounting for the taxa; (4) A color plate section illustrating various plumage characters for about 80 taxa.