His works are in public collections throughout the world including the Ulster Museum, Armagh County Museum, the Ulster Folk and Transportation Museum, the Office of Public Works in Dublin and the Limerick City Art Gallery.
Foslie contributed an algal collection named Algae Norvegicae to the Ulster Museum in Belfast, Northern Ireland.
British Museum | Museum of Modern Art | Metropolitan Museum of Art | American Museum of Natural History | Victoria and Albert Museum | Natural History Museum | San Francisco Museum of Modern Art | Honolulu Museum of Art | museum | Whitney Museum of American Art | Museum of Fine Arts, Boston | Los Angeles County Museum of Art | Solomon R. Guggenheim Museum | National Air and Space Museum | Brooklyn Museum | National Baseball Hall of Fame and Museum | Hermitage Museum | National Museum of Racing and Hall of Fame | Museum of Contemporary Art | Field Museum of Natural History | Ulster | Philadelphia Museum of Art | Imperial War Museum | Smithsonian American Art Museum | National Museum | National Museum of Natural History | Museum of Fine Arts, Houston | Denver Art Museum | Cleveland Museum of Art | Museum of Contemporary Art, Los Angeles |
Codium bursa, (Linnaeus) C.Agardh; has been found in Mulroy Bay in County Donegal in 1977 (specimen in the Ulster Museum) and 1988.
This collection was donated to the Ulster Museum by The Queen's University of Belfast in 1968.
Ronald Campbell Gunn (1808–1881) Harvey specimens in the Ulster Museum are from George Town.