The largest single foraminifer collection at the NMNH is the Cushman Collection of Foraminifera. The bulk of this collection was willed to the Smithsonian Institution by Dr. Joseph A. Cushman, and was accessioned in 1951. It originally consisted of genera and species of mostly smaller foraminifera, and included approximately 150,000 mounted slides, 25,000 type slides and figured specimens. Many additional identified primary and secondary type slides from foraminifer researchers worldwide have been added to what is known as the Cushman Collection since it came to the NMNH. Notable among these are primary type and secondary type specimens designated by A. Loeblich and H. Tappan, P. Brönnimann, H. Bolli, P.J. Bermúdez, J.-P. Beckmann, F. L. Parker, F. B Phleger, and E. Pessagno. The largest segment of the collection consists of specimens identified by a variety of researchers, including hypotypes that were illustrated in Loeblich and Tappan's 1964 and 1988 treatises, their volume on foraminifera from the Timor Sea, and other works. Most of the Collections are searchable online and details about the sieved/unsieved residues and miscellaneous items can be found in the Database of Cushman Collection of bulk samples.
Collections of smaller foraminifera associated with the Cushman Collection include:
- H. Deaderick Collection: identified slides and sieved residues; mostly Cretaceous samples from Arkansas;
- Ruth Todd Collection: identified slides and sieved residues; mostly Jurassic-Recent samples from North America and localities worldwide;
- Albatross Expedition Collection (1907-1910): identified slides and sieved residues with Recent foraminifera from Pacific, Atlantic, and Indian Ocean dredges;
- Richard Cifelli Collection: identified slides and sieved residues; Jurassic-Recent samples from North America and plankton tows from the Atlantic Ocean;
- Allen Bé Collection: Neogene-Recent identified slides, piston core sample residues, plankton tow residues from Atlantic and Indian Oceans;
- Al and Helen Loeblich Collection: Paleozoic-Recent unsieved residues and identified type slides from North America and localities worldwide;
- Irene McCulloch Collection: identified slides of Recent foraminifera from off the California coast;
- S. Geroch Collection: foraminifera from the Carpathian Mountains, including some paratypes and metatypes of Geroch species;
- Jim Mello Collection: identified slides and sieved residues of Jurassic-Recent foraminifera;
- F. van Morkhoven Collection: figured hypotypes from Cenozoic Cosmopolitan Deep-water Benthic Foraminifera (F. van Morkhoven, W.A. Berggren, A.S. Edwards (eds.), 1986 Elf Aquitane, Pau);
- Ellis and Messina Collection (formerly at the American Museum of Natural History): few identified slides; a large set of washed residues from localities worldwide. This collection is cross-referenced in card catalog files by collector, by locality, and by age.
Some of the collections of larger foraminifera include:
- Thomas Vaughan Collection: oriented thin sections of Mesozoic and early Cenozoic larger foraminifera mostly from North America;
- Paul and Esther Applin Collection: well samples, oriented thin sections, and microslides of Mesozoic and Cenozoic larger foraminifera;
- W. Storrs Cole Collection: oriented thin sections of Cenozoic larger foraminifera and raw samples from localites worldwide;
- Raymond Douglass-Lloyd Henbest Collection: oriented thin sections of fusulinids from North America and localities worldwide.
Other microfossil collections associated with the Cushman Collection include:
- Primary type slides of radiolaria, thecamoebians, and chitinozoa;
- Helen Foreman Collection: Mesozoic radiolarians on strewn slides and acid residues;
- DSDP/ODP Micropaleontological Reference Center Collection: foraminifer sieved residues, calcareous nannofossil smear slides, radiolarian strewn slides, diatom strewn slides, and lithologic smear slides from Deep Sea Drilling Project and Ocean Drilling Program cores worldwide (Legs 1-144).
Many of the collections listed above include the donors' research notes and libraries. The largest of these is the Ruth Todd Memorial Library, which began as Joseph Cushman's library and was continued through the efforts of Ruth Todd and Doris Low. This includes over 25,000 books and reprints on foraminifera, and a card catalog of over 98,000 species cards (including bibliographies, species descriptions, and specimen images).