- Obituaries; May 1961
- Bibliography and Summary of Autobiography; Dec. 1956
- Correspondence; 1900-1903, 1905-1906, 1908-1909, 1911, 1919, 1957
- Paleontological Notes about the San Lorenzo Area; n.d.
- Specimen Lists and Misc. Notes; n.d., 1903, 1905-1907
- "Fossils of the California Oil Fields"; n.d.
- "Report on Mr. Eldridge's California Fossils"; n.d., 1903
- "The Faunal Relations of the Carrizo Creek Beds of California"; by Ralph Arnold [typed manuscript];
- "On the Use of the Name Vaqueros for the Lower Miocene of the Coast Ranges of Central California";
by Ralph Arnold [typed manuscript]; n.d.
- "Notes on the Stratigraphy and Paleontology of the Southwestern San Joaquin Valley, California"; given
in answer to a request contained in letter from W. C. Mendenhall, to Ralph Arnold, dated November 30, 1906; 1906?
- "Dome Structure in Conglomerate"; by Ralph Arnold; Sept.-Oct. 1907
- "Metamorphism by Combustion of the Hydrocarbons in the Oil-Bearing Shale of California"; by Ralph
Arnold and Robert Anderson; Nov.-Dec. 1907
- "New and Characteristic Species of Fossil Mollusks from the Oil-Bearing Tertiary Formations of Santa Barbara
County, California"; by Ralph Arnold; Dec. 1907
- "Extracts from Report on Properties Near Lonoak, Monterey Co. for the Lonoak Oil Co."; by Ralph Arnold;
- "Supplementary Index to Dall's Report on the Florida Tertiary"; and "Index to Pacific Coast Species";
prepared by Harold Hannibal; n.d.