500 
PALAEONTOLOGY OF ILLINOIS. 
by the sterility of his researches. And yet it is to vegetable palaeontology 
mainly that we owe our acquaintance with the surface of our earth at the vari¬ 
ous epochs. From it we learn the character of the various changes which 
have modified this surface, and the admirable harmony of all the phenomena 
produced in its successive modifications. This branch of science has therefore 
a fascinating'attraction, as it opens to our view the treasures of a vegetation that 
no human eye has ever seen or can expect to see, except in their fossilized frag¬ 
ments, and it shows us that all the divers epochs have been constantly working 
to the same end: the preparation of a home for the human race; and this work 
has been constantly pursued in admirable harmony under the direction of a 
Supreme Intelligence. 
§ 6. ON THE STRATIGRAPHICAL AND GEOGRAPHICAL DIS¬ 
TRIBUTION OF THE FOSSIL PLANTS OF THE COAL 
MEASURES. 
European palaeontologists, who have especially studied the fossil plants of 
the Carboniferous strata, Brongniart, Goppert, Schimper, Geinitz, etc., have 
admitted that the distribution of these plants is modified according to the age 
of each bed of coal, and that, therefore, the horizontal position of the coal strata 
may be recognized by species peculiar to each. These views, as it now ap¬ 
pears, (1) have been advanced on theoretical ground, or are based on local ob¬ 
servations which cannot be considered as furnishing conclusive proofs; for 
local modifications in the succession of species of plants may be the result of 
mere local atmospherical, or geographical changes, which do not affect the 
characters of the whole flora, and therefore the comparative distribution of 
the fossil species of plants of an epoch can not be ascertained, but from the 
examination of this flora over the whole extent of its domain. A question of 
this kind can certainly be examined in our country with better chances of a 
definitive solution, than in any other part of the world, for our coal fields are of 
vast extent, the disturbances of stratification are rare or uniform, easily recog¬ 
nized by geologists, and the identification of the coal strata is ascertained at 
different localities from stratigraphical evidence. 
From the beginning, bf my researches, iff 1850, on the fossil flora of our Coal 
Measures, they have been pursued especially in view of obtaining positive data, 
marking changes in the vegetable constituents of each coal bed, according to 
its age, and therefore of recognizing species of plants peculiar to each (leading- 
species), which would serve for their identification. As my views on the sub- 
(1) From the authority of Prof. Brongniart, in letters, 1869. 
