88 Proceedings of the Royal Physical Socrety. 
The two principal divisions given by Lesquereux are :— 
I, Pre-Carboniferous. 
II. Coal-Measures proper. 
These are further divided as follows :— 
I. Pre-Carboniferous. 
1, Devonian. 
Pocono Sandstone. 
Sub-Conglomerate. 
4. Inter-Conglomerate. 
oo bo 
II. Coal-Measures proper. 
1. Anthracite Fields. 
2. Bituminous Fields. 
In vol. ii. of the same work, at page 883, a table brought 
up to date of publication is given, showing the distribution 
of the plants described in the three volumes on the United 
States Coal Flora. This is prefixed by ‘A List of the 
Species of Fossil Plants found at each Locality.” ? 
Turning to the plants recorded from the Sub-Conglomerate 
of Arkansas,® from “ various coal-beds of the same horizon,’ 
we find included the Sphenopteris communis, Lesqx. Asso- 
ciated with it are species, some of which in Britain, and, I 
believe, in Europe generally, are characteristic of, and 
restricted to, the Lower Carboniferous, and along with 
these a greater number of species which in Europe are 
characteristic of Upper Carboniferous Rocks, and to the 
Lower and Middle Coal-Measures of that division. 
Such an admixture of species is so contrary to what 
Carboniferous Paleobotany has taught us in Europe, that 
one cannot help suspecting that beds of very different ages, 
and which belong to more than one series, have been classed 
together under the term of Sub-Carboniferous, and it appears 
to me that some of the rocks included by Lesquereux under 
this name belong to his ‘‘ Coal-Measures proper.” 
1 Published in 1884. 2 Loc, cit., vol. iii., p. 849. 
P 
3 Loc. cit., p. 854. 
