The natural historian Richard Harlan was a pioneer in the study of comparative anatomy and vertebrate paleontology in the United States during the years following the War of 1812. Having received his medical degree from the University of Pennsylvania in 1818, Harlan was employed as an instructor of anatomy at Joseph Parrish's school and at the Philadelphia Museum. A practicing physician and member of the Academy of Natural Sciences of Philadelphia and the American Philosophical Society, Harlan made important contributions in comparative neuroanatomy, paleontology, herpetology, and systematic zoology. He died shortly after moving to New Orleans in 1839. Harlan's journals document two of the three overseas voyages he undertook during his lifetime. The first took place in 1816-1817 when Harlan was still a medical student, accompanying an East Indiaman to Calcutta as ship's surgeon. The second took place when Harlan was at the peak of his career in 1833, venturing to England, France, and Italy to strengthen contacts with European colleagues. Interesting travel narratives in themselves, the journals mingle enthusiasm for the new and exotic with a touch of Harlan's truculance. The European journal includes a valuable account of the 3nd meeting of the British Association for the Advancement of Science at Cambridge at which Harlan delivered a paper on fossil reptiles.

George Ord made important contributions as an ornithologist and writer but is also famous for his contempt of fellow ornithologist John James Audubon. Throughout his life he published numerous scientific articles and assisted in completing Alexander Wilson's life's work, American Ornithology; or, The Natural History of the Birds of the United States. Ord also left his mark as a member of the American Philosophical Society and as the president of the Academy of Natural Science of Philadelphia. The George Ord collection consists primarily of outgoing personal correspondence to Charles Waterton ranging from 1831 to 1866 that highlights Ord's professional as well as personal affairs, most notably his hostility toward Audubon. The collection is supplemented by correspondence of Ord's to and from various individuals regarding personal and business matters.