310 J. W. Dawson on American Devonian. 
but still only a small proportion of the species, are probably 
Carboniferous. In Pennsylvania, in so far as j 
the statements of Mr. Lesquereux and the figures given by Prof. 
Rogers, the flora of the ‘‘Vergent” and “Ponent” series ap- 
oe to be of similar character with that of the Chemung of 
ew York. 
In Europe the observed facts are not dissimilar from those 
above stated. Goeppert enumerates fifty-five species as known 
to him in the Upper Devonian, and of these only six seem to 
be Lower Carboniferous. Of forty-six species from the Cypridina 
Shales of Thuringia, described by Unger, only four are Carbonif 
erous. The scanty flora of the Devonian of Scotland and Ire 
land, described by several British authors, appears to be equally 
distinct from that of the Carboniferous rocks, while it closely 
resembles that of our American Upper Devonian. It is also to 
be observed that several generic and sub-generic forms of the 
Devonian are wanting in the richer flora of the overlying system. 
In the Carboniferous system, while it is true that there are 
somewhat different assemblages of plants in the Lower, Middle, 
and Upper members; and that, within these, there are minor 
differences, arising probably from local causes affecting the er 
tribution of species, and also from the greater or less amount : 
driftage, and the greater or less coarseness of the sediments; 
there is a grand unity of the fossil flora throughout. Even 
the lowest Carboniferous beds, at least in Eastern Americ re 
genera and most of the species are identical with those of Fo 
middle Coal Measures, separated from these lower beds ¢! he 
arine Limestones and the Millstone Grit. On the other ii 
so soon as we descend to the Devonian, we find some new gene™® 
and a distinct assemblage of species. athe 
The only apparently exceptional case known to me, an Witt 
may have some connection with the facts stated by Prof. rich 
chell, is that of certain beds at Akron and Richfield, Ohio, "ie 
have, I believe, been regarded as equivalent to the bed :. 
vonian of New York. In asmall collection from these es E 
shown to me by Prof. Hall, I observed two species W! the 
regard as identical with Lower Carboniferous forms, W a 
an 
_ distinct, and characteristic of another period. I do not at , 
Tocks including one flora and a part of another almost en evel 
