476 
PALAEONTOLOGY OF ILLINOIS. 
V 
This table enumerates 256 species of fossil plants, or more than double the 
number of those which were known from Illinois at the time when the second 
volume of the State Geological Report was published. The catalogue of the 
American fossil plants which served as a point of comparison for the table pre¬ 
pared for that volume, p. 464, enumerates 280 species, (4-26~from-Tilinois) even 
comprising some pertaining to the Devonian strata. It is, therefore, evident 
that the assertion, concerning the insufficiency of our knowledge of the flora 
of the Coal Measures of Illinois and of the future discoveries promised to con¬ 
tinued researches, is fully corroborated by facts. Of the recently discovered 
species, seventy-nine are considered as new, and forty, though known already 
from Europe, had not been recognized before in our American Coal Measures. 
The species marked in the table as from Morris and from Mazon creek, are 
from the same geological horizon. The bed of shale overlaying the coal at 
Morris covers, apparently, the whole extent of the Coal Measures of Grundy 
county. At Morris, this shale contains but few nodules or concretions, while 
at Mazon creek these nodules are found quite abundant, having been washed 
from the shales into the bed of the creek. The two localities are separated in 
the table merely to indicate the proportion of species preserved in shale or in 
concretions, and to show the difference in the nature of the fossil remains. 
About 180 of the species enumerated in the table have been found at Morris 
and Mazon creek. This remarkable predominance is due to peculiar circum¬ 
stances : 
1st. It is at and around Morris that an uninterrupted series of researches has 
been pursued by the two ardent and clever investigators, Messrs. Jos. Even 
and S. S. Strong, so often named in this Report. Researches of this kind, in 
which the miners often become interested and afford valuable assistance, offer 
the best chances to make new discoveries. They also enable the observer to 
obtain, when still in place and before the fragments are scattered, specimens 
of the different parts of a plant; to compare the different organs, or the same 
organs in different positions, and thus to become better acquainted with the 
true nature, and with the variations of forms of the same vegetable. 
2d. In the shale of Morris, there is not only a great abundance of remains 
of plants, but the coal which it covers is opened either by shafts, or by drifting 
at numerous and distant places, and therefore the flora is exposed in its local 
varieties. The distribution of plants in the coal epoch was evidently governed 
by the same laws as is now the vegetation of our swamps. There was a gen¬ 
eral uniformity of species, with a constant diversity of groups on small areas- 
As we see now in the peat bogs, here the ferns, there the grasses, or the rushes 
or the mosses, according to the degree of humidity of the surface, which varies 
at every step, we find, in examining the fossil plants of a given area, a con- 
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