Type material for 83 nominal species of fossil crustaceans are in the Invertebrate Paleontology Collections of Yale University's Peabody Museum of Natural History. Primary types for 41 nominal species include 21 holotypes, 4 lectotypes and 76 syntypes (representing 15 nominal species). Secondary types for 17 nominal species include 29 paratypes and 3 paralectotypes. Tertiary types of 47 nominal species include 200 hypotypes. Most types are from Mazon Creek (Illinois) and New York State, and have been described by C.E. Beecher, J.M. Berdan, H.K. Brooks, James Hall, M.J. Rathbun, H.B. Roberts, P.E. Raymond, C.E. Resser and E.O. Ulrich.