II2 THE AMERICAN NATURALIST. [Vov. XXXIII. 
sperms, nearly all of them included under living genera. Many 
of these now inhabit the region, such as Dzospyros, Juglans, 
Liriodendron, Magnolia, Populus, Salix, etc. ; but others are 
of more southern distribution, such as Bauhinia, Cinnamomum, 
Eucalyptus, Ficus, Laurus, Passiflora, Sequoia, etc. 
No living species is recognized, although close specific rela- 
tionship is commented upon in several instances, and is indi- 
cated in at least one of the names adopted (Magnolia glaucoides). 
The most significant feature of the flora as a whole is the 
complete reversal of the proportions between the angiosperms 
and gymnosperms as compared with their proportions in the 
preceding flora, the angiosperms being now overwhelmingly in 
the ascendant, while in the gymnosperms the conifers are more 
abundant than the cycads. 
The genera also indicate a less tropical climate than that 
which previously prevailed, but one which was considerably 
warmer than now obtains in the region. 
After the clays had been laid down as estuary or brackish 
water deposits, the submergence continued, and we next find 
the clay marls, representing the transition to marine condi- 
tions. In these the land vegetation is less abundant, but is 
not noticeably different in its general characters from that 
which preceded it.! 
The subsidence continued and true marine conditions super- 
vened. The marls were deposited, and in them nothing but 
marine organisms are preserved. Thus far we have not found 
any record of the land vegetation which occupied the region 
during this period, but in the west the conditions were differ- 
ent, and the remains of Upper Cretaceous plants are abundantly 
preserved in the Laramie and allied deposits. In these most of 
the Middle Cretaceous genera are found to continue, and a 
number of new ones to appear, but the species in all but a very 
few instances are different, and the monocotyledons begin to 
assume prominence for the first time, in the form of fan palms. 
Generically this flora is more closely related to our living 
flora than was that which had preceded it. The number of 
1 Hollick, Arthur. The Cretaceous Clay Marl Exposure at Cliffwood, N. J., 
Trans. N. Y. Acad. Sci., vol. xvi (1897), pp. 124-136. 
