Abstract The spore-pollen assemblage from Lower Cretaceous strata mapped as Arundel Clay in Maryland is compared with the dispersed spores and pollen from the Upper Cretaceous Magothy Formation, also in Maryland, and with those from the Lower Cretaceous Wealden sequence in England. The striking similarity of the two Lower Cretaceous assemblages, which consist almost exclusively of fern spores and gymnospermous pollen, is demonstrated by the relatively large number of species common to both assemblages, in spite of their wide geographic separation. Of thirty-five species identified from the Arundel samples, twenty-three also occur in the Wealden beds. Similarly, of fifteen key species in the Arundel, twelve are conspecific with forms in the Wealden assemblage. Whereas comparative studies emphasize the similarities between the Lower Cretaceous assemblages, they indicate just as forcefully the dissimilarities between the Arundel and Magothy assemblages, each of which contains its own distinctive, diagnostic and vastly different spore-pollen assemblage. None of the commonly-occurring or distinctive forms in the Magothy occurs in the Lower Cretaceous assemblage, and of the species identified from the two assemblages, only five are common to both. An even more obvious difference is the fact that no angiospermous pollen were observed in the Arundel However, in the Magothy angiospermous pollen constitute approximately forty percent of the dominant or distinctive species. Furthermore, the Magothy assemblage, which is composed of about twice as many species as are in the Arundel, is characterized by having, in genera1, species whose morphologic features are more complex and more advanced than those shown by most specimens in the Lower Cretaceous assemblage.