L, Lesquereux on the Coal Formations of the United States. 15 
Art. IV.—On some questions concerning the Coal formations of 
the United States; by Leo LesQuErEUx.—(Continued from 
vol, xxx, 384.) : 
General Remarks on the Coal Plants and their Study. 
Hooker has remarked at length on the difficulties attending the 
n admit, 
nished by paleontological botany and their uncertainty com- 
ared with those afforded to Geology by fossil animal remains, 
emains of fossil plants are preserved in two ways: 
First. We find, especially in the shales overlying coal-banks or 
occupying their place, the flattened surface, the printed outlines 
of some peculiar vegetable organs. They are mostly leaflets of 
ferns, either without traces of fructification, or with the fructifi- 
cation obliterated and dimly visible through the parenchyma of: 
the leaves;+ or parts of fronds, broken pinnse detached from the 
common rootstock; or pieces of flattened stems without leaves, 
generally bearing on the surface some peculiar striz or cicatrices 
left at the point of attachment of the leaves; or a few isolated 
and broken fruits, apparently nutlets of unknown relation and 
structure, 
econdly. We find also fossil botanical remains, either silicified 
or transformed into coal or mineral charcoal. Silicified wood 
1s Common enough in some strata of sandstone intervening be- 
tween some beds of coal. But it represents parts of stems, or of 
half decayed trunks, of which the bark has generally been taken 
off or is entirely obliterated. Such specimens of course expose 
to the student the internal structure of the wood but nothing else, 
en the remains of fossil plants aré*found reserved in coal 
or charcoal, every trace of a complex organism has disappeared 
? 
and nothing can’ be seen by a microscopical examination but 
1solated vessels of various forms and size. 
We have thus either flattened organs of plants of which we 
can only see the outline, to which we cannot by any means refer 
the organs that are essential for determination, like stems, flow- 
oe 7 is well to recall the fact that the a - gah sey pecan the fossil 
coal plants, though some of them may apply to the fossil flo e 
+ The lower wae of the ferns oe BS bears the fruit, is mostly the one insepara- 
bly attached to the stone. 
