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mine the age of the deposit, the 250 species of plants, or the 
isolated Cretaceous Fauna ? . 
Another difficulty of this kind is the determination of the age 
of the Upper Series of the Bohemian Gas Coals. A Permian 
Fauna exists with Carboniferous species of plants, which is to 
determine ? It appears to me that the deposits should be referred 
to one or the other period, according as to whether the Fauna or 
Flora is the most distinct and decisive. 
A practical application of Prorzssor Hvu1’s remark is to be 
found in the Bristol Coalfield. Some years ago the base of the 
Pennant, locally termed the Holmes Rock, was said by certain 
geologists to be the Millstone grit, which would have led to 
error; in reading the structure of the Bristol Coalfield, this 
error was, however, pointed out by Mr. H. Cossnam, F.G.S., 
at the British Association, held in Bath in the year 1864. 
Now had those Gentlemen who examined and mapped this 
rock as Millstone grit, known the Flora found in it, and com- 
pared it with that of the Millstone grit, it is difficult to see 
how they could have made the mistake, allowing for its then 
obscure position. 
In the Geological Magazine for August, 1878, page 34-5, 
Mr. H. E. Hrerstery, C.E., contributes a paper on the “ Correla- 
tion of the Somersetshire Coalfield,’ and shows that there are 
at least substantial reasons for questioning its correlation. 
This doubt, however, might be easily removed by a critical 
determination of the Fossil Flora. 
The Carboniferous plants were most, if not all, Cryptogamic; 
some however possessed a higher degree of organization than is 
general with that division of the vegetable kingdom, hence they 
are considered by some writers to have belonged to the Gym- 
nospermous Conifers. 
The climatal and physical conditions which prevailed over 
the S.W. as well as the whole of England during the long 
Carboniferous period may be best judged by what we are 
able to gather of the surrounding circumstances. 
There is unmistakeable evidence of slow and definite sub- 
sidence, and the accumulation of sedimentary matter ; the 
