304 D. WHITE — AGE OF LOWER COALS OF HENRY CO., MISSOURI. 



there is a strongly marked contrast between the flora of those coals and 

 the species found in the Pottsville series or " Millstone Grit," which lies, 

 in most cases, close beneath them, there being in fact very few species in 

 common. The plants of the upper portion of the Pottsville series agree 

 in the main with the flora of the Millstone Grit of Europe. The Lower 

 Coal Measures of Great Britain and the zone of Vicoigne in the Franco- 

 Belgian basin, with their intermingling of Millstone Grit or Culm species 

 with the earliest of the Coal Measures types, appear, so far as we know at 

 present, to be unrepresented by any coal-bearing interval in the bitu- 

 minous regions mentioned above. It seems more probable, however, 

 that this interval is in some cases concentrated in the deposition of the 

 highly variable upper benches of the Pottsville series in the northeastern 

 states, rather than that it is represented in these regions by a break or 

 that we have here a case of homotaxy without contemporaneity in the 

 floras. It is proper to state in this connection that in the greatly ex- 

 panded sections of the Lower Coal Measures in the Upper Kanawha 

 region of West Virginia, which is in the same great Appalachian basin 

 and which was throughout Mesocarboniferous time united with the north- 

 ern plant-bearing areas by continuous shorelines, the characteristic forms 

 of the lowest coals of the Lower Productive Coal Measures of the states 

 north of the Ohio and Potomac rivers are not met until we arrive at a 

 point several hundred feet above the Pottsville series as hitherto limited. 

 The floras of the Kanawha series, extensive collections from which are 

 now in the writer's hands for examination, will be found to show a lower 

 zone of mingled types corresponding very closely to the Lower Coal Meas- 

 ures of Great Britian or the lower zone of the Franco-Belgian basin. 



