This collection contains mostly entomological material, with much information on the description and identification of particular insects, entomological collections, and the study of entomology in Europe and the United States. In addition, there are materials on medicine and hospitals during the American Civil War, on the Corps of Topographical Engineers, the United States Army, on natural history in the United States, and on the LeConte's family. Some letters are written to President Rutherford B. Hayes and concern the Commissionership of Agriculture, for which LeConte was considered, but not appointed. Letters of John Eatton LeConte and Joseph LeConte are included.

There are botanical notebooks which concern Bunbury's study of fossil plants in general, with special studies on the fossil plants in the Geological Society in Richmond, Virginia, and at Aix-la-Chapelle, Cape Breton Island, and Pennsylvania. There is also a historical sketch of eminent English naturalists.