Observations on the Thunder Dance of the Bear Gens of the Fox Indians.  By Truman Michelson.  Green cloth hardcover, Bureau of American Ethnology bulletin 89, pub. 1929, 73 pages.  Title page has a stamp for the former owner.  Two accounts of the Thunder dance were written by two native informants with songs given in the Fox syllabic style; English translations.  Apparently the Thunder dance was some sort of semi-secret and ritualistic dance.  A gens would be a group of people related through male ancestors.  Slim volume, shipping weight less than 1 pound.