476 PALAEONTOLOGY OF ILLINOIS. 



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, (120 from Illinois) 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 snafts, 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 eon- 



