The collection consists of original manuscripts of Swainson's books and some miscellaneous papers.
- Swainson 01-03. Original manuscript for 'A Preliminary Discourse on the Study of Natural History' published in 1835. It includes additional and suppressed passages.
- Swainson 04-06. Original manuscript for 'On the Natural History and Classification of Quadrupeds' published in 1835, including additions and alterations.
- Swainson 07-09. Original manuscript for 'A Treatise on the Natural History and Classification of Birds' published in 1836.
- Swainson 10. Original manuscript for a work entitled 'On the classification of Animals', said to be parts 3 and 4 of the printed book.
- Swainson 11. An imperfect original manuscripot for 'Geography of Animals', probably published as 'A Treatise on the Geography and Classification of Animals' in 1835.
- Swainson 12. Manuscript for articles on Geographic Zoology written for 'An Encyclopaedia of Geography' edited by High Murray.
- Swainson 13-14. Original manuscript for 'A Treatise upon Animals in Menageries' (Quadrupeds and Birds) published in 1838.
- Swainson 15. Original manuscript entitled 'Descriptions of Two Centenaries and a Quarter of New and Little known Birds', which was printed in the Menageries volume of the Cabinet Cyclopedia of Natural History by Dionysius Lardner, published in 1830.
- Swainson 16. Original manuscript of a volume 'On the Rise and Progress of Systematic Zoology' published as part of D. Lardner's Cabinet Cyclopaedia of Natural History (1830), with additions and improvements.
- Swainson 17. Original manuscript of 'Entomology as connected with Agriculture and Gardening' published as part of the Encyclopaedia of Gardening edited by John Claudius Loudon from 1824.
- Swainson 18. Notes and proofs entitled 'Mexican Zoology'.
- Swainson 19. A portfolio with 'Old Zoological Mss.' of various contents.
- Swainson 20. A manuscript with title 'On the Natural Arrangmenet of the Testaceous Mollusca'
- Swainson 21. A manuscript with title 'General Ornithology, vol. 1'
- Swainson 22. A packet of miscellaneous manuscripts, unsorted.
- Swainson 23. Copies of Annual Reports of the Bolanos Mining Company, with some letters.
- Swainson 24. Description of 'Northern Zoology'.