BOTANICAL GAZETTE. 171 
nearly destitute of vegetable remains, but the Senonian immedi- 
ately overlying it, with which the Canadian geologists have cor- 
related certain rich plant beds of British Columbia, and to whic 
Heer’s flora of Patoot, Greenland, must be referred, yields more 
than 350 species. The Laramie Group of the western United 
States is thought to be extreme Upper Cretaceous. This is very 
rich in plants, and 333 species have already been described from 
this horizon. 
The Tertiary flora is much more abundant than even that of 
the Carboniferous. The Eocene furnishes near y 800 species 
(including our Green River Group and the Paleocene beds of 
Sezanne and Gelinden). The Oligocene of Europe yields a some- 
what larger number. The maximum is attained in the Miocene, 
from which more than three thousand fossil plants are known. © 
e Miocene practically closes the geological series so far as veg- 
etable paleontology is concerned. Only about 150 Pleiocene 
species exist, and a still smaller number from the Quatenary. 
Borantcan Virw.—I._ First appearance of types. 
The Oldhamias of the Cambrian, mentioned in the last paper, 
are classed as marine alge of the order Floridee. The ferns, 
Equisetinece, and Lycopodineer all appeared in the Lower Silurian. 
One Species of Cordaites, which is now regarded as the ancestral 
and B 
The Cycadacee and the Monoeotyledons have their earliest 
known representatives in the Carboniferous. The order Gnetacee 
'S represented, according to Heer, in the Oolite of Siberia by his 
Species Hnhedrites antiquus. The Dicotyledons first appear 1 the 
Urgonian of Kome, Greenland, through Heer’s single species 
opulus primeva. All three of the divisions of dicotyledonous 
Plants occur in great abundance in the Cenomanian. If the 
" Benus Selaginella is regarded as belonging to the Ligulate, this 
small transitional type also first appears in the Cenomanian, at 
Atane, Greenland. co 
u the leading types of vegetation are thus introduced with- 
out f0ing later ews ihe peoloniad scale than the middle Creta- 
ceous, 
I. Age of maximum relative predominance of each type. 
; The marine alge, of course, being the only vegetation, were 
preme during the Cambrian and early Silurian. The maxi- 
ea relative redominance of each of the other principal types 
“S Teached as follows: The ferns in the Permian, the Equiset- 
=I 
