The fonds reflects the scientific and literary outreach activities of the Montreal Natural History Society over the course of its existence and contains correspondence, minutes, financial records, council and committee reports, membership lists, donation lists, catalogues of holdings, newspaper clippings, lecture advertisements and weather maps. In addition, the fonds includes reference material to other societies and information regarding the publication and creation of the Canadian Naturalist and Quarterly Journal of Science, Canadian Naturalist and Geologist and the Canadian Record of Science.

The fonds is composed of the following series: 1) Accounting Records (1860-1917); 2) Administrative Records (1833-1887); 3) Catalogues (ca.1829-ca.1925); 4) Correspondence (1871-1896 with gaps); 5) Essays and Lectures (1829-1852); 6) Minutes (1827-1832,1844-1923); 7) Montreal Microscopical Society (1884-1906); 8) Reports (1828-1881 with gaps); 9) Weather Maps (1895-1897).

Fonds consists of contemporary manuscript copies of various legal records and instruments relating to the Capacci family. Includes one manuscript written on parchment in pale brown ink, ruled in pale brown ink, and bound in full contemporary blind tooled calf with laid paper endpapers and remnants of ties on covers, as well as a smaller booklet, written on parchment glued into a laid paper wrapper. Documents appear to be dated between 1556 and 1583 and are written in Latin and Italian (sometimes alternating within document). The legal instruments appear chiefly related to the dowry of Orietta Capacci (the dowry is also referenced in an Italian note in a later hand (1650?) inside front cover). Some names found throughout the documents include Orietta Capacci (or Orietta de Capacci) and Annibale (or Anibal) Camillo de Capacci.