PLANT REMAINS IN NORTH AMERICA, 83 
scribed a singular collection of coniferous fossils from strata of Calca- 
reous age occurring in the Belgian province of Hainault, but with 
them is associated a Cycad belonging to an extinct tribe of the Order. 
No trace whatever remains of these Cretaceous plants in the existing 
flora of the regions where they are found. A corresponding facies of 
vegetation can be found at the present day only in tropical regions, 
and to a considerable extent the same may be said of the vegetation 
of the Tertiary strata. The tropical character is not so strongly pro- 
nounced, but the Orders and genera represented are more southern 
forms than those now living in Europe. Two or three Palms, species 
of Smilax, Cinnamomum, Liquidambar, Liriodendron, etc. ; numerous 
forms of Proteacee, referred to the modern genera Banksia, Dryandra, 
Hakea, and Persoonia, and coniferous forms belonging to Sequoia, 
Taxodium, Glyptostrobus, Frenela, etc.,—form a group of plants the mo- 
dern representatives of which must be sought sometimes in America, 
sometimes in Australia, and at others in Asia or Africa, but least of all 
in Europe, and, in the few cases that do occur in Europe, only in 
the Mediterranean region of the Continent. The Tertiary flora is 
much further removed from the existing vegetation of Britain than 
it is from the Cretaceous flora, and yet from this it is very clearly 
distinguished. 
n America the relations of these successive floras are very different. 
Many genera are common to each of the three periods, and no very 
marked line of distinction can be drawn between either of them. Pro- 
fessor Newberry has just given us the means, of forming an approximate 
estimate of the facies of the two extinct floras,* in a recent Essay, which, 
besides containing much new and original labour, gives a narrative of 
all that has been done before. The plants found in Cretaceous rocks 
were at first believed to be of Tertiary age, on account of the modern 
character of the genera found among them. The true stratigraphical 
position of the rocks in which they occur has, however, been esta- 
blished, beyond a doubt, from the discovery of unmistakable Cretaceous 
shells in them, like Gryphaa Pitcheri and Inoceramus problematicus. 
The forms enumerated by Newberry contain only a few, which have 
disappeared from North America, such as Cinnamomum, Cissus, Ficus, 
* eb ess on the e Extinct Floras of North America, with description of 
e new species of Fossil Plants from the Cretaceous ~~ e. uot Strata. 
rives of the "poa of Nat. History in New York, vol. ix 
