496 BROOKLYN BOTANIC GARDEN MEMOIRS 
The groups which find no existing parallel in the genus may be 
questioned as really representative of Quercus. The Fraxinifoliae 
are not known since early Tertiary time, but they constituted about 
It percent of American Cretaceous species referred to this genus, and 
about 17 percent in the Eocene. The Distinctae formed about 15 
percent through the Cretaceous, Eocene and Miocene, with changing 
species. The Suspectae constituted about 20 percent of the whole 
in the Cretaceous, but only about 10 percent in the Eocene, and they 
fell to some 4 percent in the Miocene. Neither of the groups that I 
have called Myricaefoliae and Bicornes is known to have had more 
than a small and transient representation—Q. praeundulata in the 
Cretaceous and Q. Ramaleyi in the Miocene for the former, and 
Q. bicornis and Q. negundoides in the Eocene for the latter; and the 
Dallieae are represented only by Q. Dallii of the Eocene. 
The ancient foliage types more or less comparable with those of 
today show the following relative abundance at different times, so 
far as records go: The chestnut type, now most largely represented, 
with nearly half the existing American species, formed one tenth of 
the whole in the Cretaceous, over a third in the Eocene, and about 
one seventh in the Miocene: over a fourth of the known Pleistocene 
oaks have this kind of foliage. About 16 percent of the known 
living American oaks have lobed leaves, and nearly half of those 
known from the Pleistocene are of this general kind; though about a 
third of those known for the Miocene are of this type, none of them 
has bristle-tipped lobes so far as I know; and in the Eocene only 
about 3 percent are found to have had lobed leaves. The pungent 
or holly-like type, now constituting about 4 percent of the whole 
and represented by one form in the Pleistocene, contained about 15 
percent of the Miocene and 9 percent of the Cretaceous forms, though 
it is not yet recognized in Eocene deposits. As might, perhaps, be 
expected, entire-leaved oaks, now represented by over a third of the 
known species, have been abundant throughout the history of the 
genus, and nearly a third of the Cretaceous, a fifth of the Eocene, and a 
fourth of the Miocene and of the Pleistocene, species possessed this 
type of foliage, which today is often found associated with holly-like 
or comparably toothed leaves, often in the same species or even on 
the same individual. | 
It does not seem profitable to attempt to draw climatic inferences 
from what I can see in these fossil oak leaves. Some of the entire 
leaves appear to have been rather coriaceous, as in certain semi- 
xerophytic species now living on the Mexican table-land, and these 
and the holly-leaved forms may have been somewhat xerophytic. 
Most of the leaves look as if they might have belonged to mesophytes. 
