8 FLORA OF LOWER COAL MEASURES OF MISSOURI. 



Aviciilopecten iwovidens (Cox)? was also found in the plant shales over 

 the Jordan coal. Spirorhis carhonaria is frequently present. Unfortunately 

 the faunas of the trans-Mississippian Coal Measures have not yet been 

 studied sufficiently to invest these species, most of which are supposed to 

 have a wide vertical range in the Coal Measures, with any definite or avail- 

 able correlative value. 



A number of insect fragments have been found among the plant mate- 

 rial. Several of these specimens have been described by Professor Scudder^ 

 as Paromylacris clintoniana Scudder, JEtohlattina clintoniana Scudder, and 

 Anthracoblattina americana Scudder. Two or three other fragments have 

 not yet been examined by a specialist in fossil insects. 



The proximity of the lower coals from which the plant fossils wei'e 

 obtained to the Ferruginous sandstone, or even to the eroded beds that 

 comprise the Mississippian floor of the Coal Measures, has ah-eady been 

 noted. The shore lines of the encroaching Carboniferous sea adapted 

 themselves to the erosional topography of the Mississippian land. The 

 thickness and regularity of the sediments in the bordering marshes or 

 lagoons seem to have varied with the depth and extent of the marginal 

 depressions, the lowest beds being most irregular The Jordan coal, like 

 that beneath it, may be presumed to have been formed in these marginal 

 swamps. It lies in basin-like areas of varying size, some containing but a 

 few acres, others extending many miles. In general it is thickest and best 

 in the interior of the basins, where it lies lowest, while it thins toward the 

 rising margins of the embayments or swamps. Yet, while it thins beyond 

 recognition, and can not be continuously traced in many cases from one 

 embayment or estuary across to the next along the old shore line, it may 

 in the region of Henry County be usually recognized by the constancy of 

 its flora as well as the character of the coal. In PL I, from a photograph 

 of the stripping at Hobbs's mine, near Deepwater, the coal is seen to rise 

 and feather out on a rather steej) slope of the Ferruginous sandstone. 

 At other points, presumably farther out toward the main basin, a consid- 

 erable body of shales and sandstones intervenes in the old embayments, 

 although the interval has not yet been observed to reach 100 feet at any 

 point in this part of the State, while landward the coal appears to have 



' Bull. U. S. Geol. Surv., No. 124, 1895, piJ. 53, 66, 129. 



