These are principally letters to Charles Edward Sayle on musical programs and to Thomas Roscoe Rede Stebbing about the Linnean Society, the Royal Society, and the publication of Charles Darwin's papers. There is also a letter of Charles Darwin to Stebbings and several letters of Francis Darwin to other persons. In addition, there are several letters to William Bowman (as well as from Theodor Wilhelm Engelmann to Bowman), and one from Raphael Meldola.

This collection is comprised of materials from seven repositories and includes correspondence from Banks' colleagues and explorers, such as John Hope, Josiah Wedgwood, Georg Forster, and Captain William Bligh; records of expenses for voyages and journeys; and journals kept during voyages to New Foundland and Labrador (1766) and around the world with Captain James Cook (1768-1771). Topics include botany and horticulture, marine life, and collecting specimens.