Thls is a key, with flgures and descrlptlve notes, to asslst in the determlnatlon of 39 genera of the more common and slgnlflcant klnds of pollen preserved as fosslls in peat beds of the Great Lakes reglon. A brlef dlscusslon of technlque is lncluded. Slx conlferous genera, 7 monocot families, and 11 dlcot orders are represented. Pollen of Sparganlum, Saglttarla, Liquidambar, Platanus, Ostrya, Carplnus, Celtls, among others, are flgured here from Amerlcan sp., and the basls of homology in Carya and Juglans pollen lndlcated.