WHEN we find a genus which is monotvpie in the existing flora, or one which contains but two or three geographically remote species, we may rest assured that the genus in question had anl interesting geological history and that its living representatives bn it z1 g e s ai are relicts of a day when the genus was widespread and (lomiflant. Notable examples, such as Liriodendron, Sequoia, and Nelumbo, may be cited. Comptonia is no exception to this rule. The single living species is confined to eastern North America, ranging as a lOIN shrub from Nova Scotia to \Manitoba and southward to North Carolina, Indiana, and Tennessee, while the number of ancient forms that have been described, is upwards of three score and amply proves the cosmopolitan character of the genus during the Tertiary periocl. Recent paleobotanists refer them as a, subgenus to \IMyrica, as is done in case of the living species by Engler (lNat i~ricehea Pflamzealjailiene, vol. 2, pt. 1, p. 28, 1889). MINoderni usage in this country, however, gives Comptonia generic rank, quite rightly so it seems to me. The space of a generation has passed since Schimper's classic Tra ie (le Paleontologie T %'letale sought to unify paleobotany)T, and the chaos of described species is even greater to-day than it was previous to 1870. Paleobotany is surely far enough advanced, it seems to me, for a more philosophical treatment, and while this little essay makes no pretension at embodying such a treatment, it is hoped that it will furnish the material that will be useful for that purpose when the proper time arrives. It is obvious enough to most botanists that existing species vary in their leaf characters through verv wide limits. I have had considerable to say about the leaf variation, atavistic ancl otherwise,