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The most abundant vegetable remains of these Lower Tertiary clay-beds 

 represent leaves of Dryophyllum. It has been remarked, in the description of 

 Quercus primordialis of Nebraska, that this species is referable to the same genus 

 Dryophyllwm established by Devey,in the description of a number of leaves from 

 the Upper Cretaceous of Belgium. These leaves are considered by the author 

 as prototypes of some species of Quercus of the Chamidobalanus section, of 

 Castaneopsis, &c, whose representatives, all tropical, inhabit at our time South 

 Asia and the adjoining islands, Borneo, Sumatra, &c. In the description of 

 Quercus primordialis I have compared its leaves to those of some varieties of 

 the chestnut-oak, which they closely resemble by their form, their denticula- 

 tiou, and their nervation. This relation seemed to me the more admittable 

 from the association of the remains of this Cretaceous species with those of 

 others like Fagus, Platanus, Magnolia, Liriodendron, Salix, Menispermum, &c, 

 which are evidently types correlative of a moderate climate. Now, on con- 

 sidering still the great variability of that ancient Dryophyllum, I find in this 

 fact another reason in favor of the relation of its species to oaks of the Lepi- 

 dobalanus section, to which belongs our chestnut-oak. This division has a very 

 large number of species ; among others, all the species of Europe and of North 

 America, some of which are endowed with a prodigious power of variability; 

 and, also, it is represented in the Lignitic of the Rocky Mountains by other 

 species, which, though of different types, as, for example, Quercus angustiloba, 

 are positively referable to this same section, mostly represented in the tem- 

 perate zone. 



To the genus Dryophyllum, or to the same type, is also referable I'hyl- 

 lites ileiiiitziiiiius, Gopp., from the Quadersandstein. In the flora of Gelinden, 

 the French authors describe four new species of Dryophyllum, and also figure 

 two species of Watelet from the Lower Eocene of the Paris basin, and 

 one species, D. cretaceum, Dev., from the Upper Cretaceous beds of Aix. 

 Four other species have also been described from Sezane by Saporta. In 

 comparing Quercus 'primordialis to these fossil leaves, its intimate relation is 

 recognized especially with Dryophyllum SaporUe, Wat., and D. Dewalquei, 

 Sap. & Mar. It differs essentially from both, however, by its shorter and com- 

 paratively more enlarged size and by the absence of cartilaginous or inflated 

 borders and teeth. From the remark of the authors of the Flora of Gelinden, 

 the same type re-appears, slightly modified, in Quercus fu rcinervis, Rossin., which. 



