Review of Recent Geological Literature. 57 
pecially Sphenopteris and Pecopteris; he notes that with two unim- 
portant exceptions all the plant species of the Missouri flora are at 
least varietally unlike the plants from the Pottsville series; and that a 
large proportion have a range through considerable thickness of Am- 
erican Mesocarboniferous, giving in consequence little aid in correla- 
tion of horizons. He finds, however, some local modifications of 
species having wide vertical range which do aid in correlation. 
Of the 123 enumerated species 39 are peculiar to the Missouri flora, 
as compared with American localities, and of these, 24 are new species. 
For comparison with the floras of other basins in the United States 
48 species of more limited vertical range are selected, and the final con- 
clusion is that the flora represents a time subsequent to that of the 
lowest coals of the Lower Coal Measures of the eastern districts, as 
the Morris coal of Illinois, the Mazon Creek beds, and the Brookville 
and Clarion coals of Ohio and Pennsylvania, but probably an earlier 
date than the Darlington or Upper Kittanning of Pennsylvania and 
Ohio; also that the Henry County flora is nearly contemporaneous 
with the "D" or Marcy coal of the Northern Anthracite field, though 
possibly as old as the "C" coal. The unconformity in Missouri be- 
tween the Henry County coals and the underlying Eocarboniferous 
surface represents no less time than was required for the deposition of the 
Pottsville series and the Clarion group of the lower productive Coal 
Measures, which have a thickness in southern West Virginia of 2,400 
feet. 
In comparison with European floras the author regards the Mis- 
souri flora as having a position between the Middle and Upper Coal 
Measures of Great Britain, or corresponding to the "transition beds," 
and to the upper zone of the Valenciennes coal field in the Franco- 
Belgian basin. 
As evidence of the value of paleobotanical correlation, it is to be 
note4 that the horizons in the British and the Westphalian coal basins 
which had been correlated by the European paleobotanists, are now 
found by the entirely independent studies of David White to be in 
each area also contemporaneous with this American flora. 
As there is a strong contrast between the floras of the Pottsville 
series and those of the immediately overlying coals of western 
Pennsylvania and westward, and since the Lower Coal Measures of 
Great Britain and the Vicoigne (lower) zone of the Franco-Belgian 
basin are not known to be represented in the American bituminous 
region, the author suggests that the European beds may be repre- 
sented in the variable strata of the upper benches of the northern 
Pottsville, and that they are probably represented by the Lower Coal 
Measures (Kanawha series) in the Kanawha region in West Virginia. 
The plants of the latter series, which he is now studying, promise to 
represent, in America, the Lower Coal Measures flora of England and 
Westphalia. (See below, page 59.) 
Another interesting suggestion of the author is that many species, 
and eyen genera, of the Mesocarboniferous plants were evolved in- 
