FOSSIL VEGETABLES. 453 
nutions of Temperature upon the Land, which 
have been inferred from the remains of the vege- 
tation of the Sea. Thus, in strata of the Transition 
series, we have an association of a few existing 
families of Endogenous Plants,* chiefly Ferns 
and Equisetaceee, with extinct families both En- 
dogenous and Exogenous, which some modern 
botanists have considered to indicate a Climate 
hotter than that of the Tropics of the present day. 
In the Secondary formations, the species of 
these most early families become much less nu- 
merous, and many of their genera, and even of 
the families themselves entirely cease ; and a 
large increase takes place in two families, that 
comprehend many existing forms of vegetables, 
and are rare in the Coal formation, viz. Cycadece 
and ConifercE. The united characters of the groups 
associated in this series, indicate a Climate, 
whose temperature was nearly similar to that 
which prevails within the present Tropics. 
In the Tertiary deposits, the greater number of 
the families of the lirst series, and many of those 
of the second, disappear ; and a more compli- 
cated dicotyledonous | Vegetation takes place of 
* Endogenous Plants are those, the growth of whose stems takes 
place by addition from within. Exogenous are those in which 
the growth takes place by addition from without. 
t Monocotyledonous Plants are those, the embryo of whose 
seed is made up of one cotyledon or lobe, like the seed of a Lily 
or an Onion. Dicotyledonous Plants are those, the embryo of 
