Correspondence, diary, expedition journal, financial material, scientific notebook and sketches, photographs, published material, including articles and newspaper clippings, and scrapbooks. Correspondence (1854-1902) includes that of Alexander Agassiz, Charles E. Beecher, E.D. Cope, James D. Dana, J.S. Diller, G.K. Gilbert, G. Brown Goode, Asa Gray, Robert T. Hill, Anna Hyatt Huntington, Hyatt’s father, Alpheus Hyatt, Audella Beebe Hyatt, Jules Marcou, Harriet Randolph Hyatt Mayor, A.S. Packard, Charles Schuchert, and Charles Walcott.

Correspondence, incoming and outgoing (1860-1932); diaries; account books; notebooks; a partial autobiography; and sketches. Correspondents include Clara Carter Hyatt Coad, Mary E. Freeman, Anna Hyatt Huntington, Archer M. Huntington, Alpheus Hyatt, Leon Kroll, Alpheus Hyatt Mayor, and Harriet Randolph Hyatt Mayor.