Bibliographer, papyrologist, collector, and historian of Merovingian tapestries. De Ricci was an expert on the provenance of rare books. He created three reference books of manuscripts and rare books: Catalogue raisonné des premières impressions de Mayence, 1445-1467 , Guide de l'amateur de livres à gravures du XVIIIe siècle , and Census of Medieval Manuscripts in the United States and Canada . In the field of Egypt papyrology, De Ricci traveled throughout Egypt, North America, and Europe to study works in various collections, publishing a bibliography of Egyptology in Revue Archéologique (1917-1918), and the Receuil Champollion (1922). He compiled specific and detailed information on each collection that he studied, which included the maiolica pottery and signed bookbindings in the Mortimer L. Schiff collection, and the Merovingian tapestries in the Pierpont Morgan collection in New York City. On completion of his Census of Medieval Manuscripts in the United States and Canada in 1934, De Ricci approached the Institute of Historical Research in London with the possibility of conducting a similar survey of manuscript sources in the British Isles. De Ricci was continuing the process of listing and gathering information, begun in 1902, when he died in 1942.
For more information on the 'Bibliotheca Britannica Manuscripta' project, please consult Joan Gibbs, 'Seymour de Ricci's Bibliotheca Britannica Manuscripta' in Calligraphy and Palaeography: Essays presented to Alfred Fairbank on his 70th Birthday (Faber, London, 1965)
From the guide to the Ricci, Seymour Montefiore Robert Rosso de-, 1902-1955, (Senate House Library, University of London)