500 PALEONTOLOGY OF ILLINOIS. 



by the sterility of his researches. And yet it is to vegetable palteontology 

 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 of my researches, in 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. 



