Consists of the personal papers of Carl H. Eigenmann in six series: Correspondence, Publications, Board of Trustees, Biological Station, Carnegie Museum, and Research.

The Correspondence series, 1884-1927 consists of Eigenmann's incoming and outgoing correspondence. While most files hold only one or two pieces of correspondence, more frequent correspondents include Indiana University President David Starr Jordan and Registrar John W. Cravens.

Eigenmann was a frequent contributor to scholarly journals, eventually writing more than 200 articles on Zoology. Although not complete, the Publications series, 1887-1926, is made up of reprints of a number journal articles written or co-written by Eigenmann, including at least three co-written with wife Rosa Smith Eigenmann.

The Board of Trustees series, 1891-1913, consists of reports on the Dept. of Zoology and the Biological Station submitted to the Board by Eigenmann. Two folders, both undated, holds fragments of numerous reports.

The Biological Station series is further organized in two subseries, Correspondence and Teaching and administrative. The Correspondence series holds correspondence about the Biological station, primarily with potential students at the Lake, but also correspondence on Eigenmann's arrest by the deputy fish commissioner at Winona Lake for using fish seines (see correspondence with Z. T. Sweeney and C. E. DeBoos). Included in the Teaching and administrative series are student research, notes, enrollment lists, and receipts and bills for the Station.

The Carnegie Museum series is further organized into two subseries, Annual reports and Correspondence. The series, however, consists primarily of correspondence having to do with Eigenmann's position as fish curator at the Carnegie Museum, a Department of the Carnegie Institute. The most frequent correspondence was carried on with the Director of the Institute, W. J. Holland.

The Research series, 1886-1924, is organized in three subseries: Catalogues and notebooks, Correspondence, and "Eigenmann relics." The series primarily consists of notebooks, catalogues, and notes made by Eigenmann. The "relics" subseries includes items collected by Eigenmann, including pine cones, sea shells and the like.