THE BOTANY OF A COAL MINE. 
291 
submerged forests, or on the banks of the rivers that brought 
down the mud in which they are preserved. 
The vascular tissues found in the coal, or seen in the film of 
charcoal, or so-cafled “ mother-coal,” that separates the coal into 
layers parallel to the surface of the seam, belong all to one or 
other of the genera mentioned. The absence of foliage, and of 
cellular plants might have been expected from the experiments 
of Professor Lindley, to which we have alluded. Many deposits 
of peat are composed almost entirely of cellular plants, and 
as the moist atmosphere, which necessarily prevailed in the 
extensive forests that covered the great areas now forming the 
coal fields of the Old and New Worlds, was specially fitted for 
the luxuriant growth of cellular parasites, such as lichens and 
mosses, it is probable that these simpler forms greatly helped 
to make up the amorphous substance of the coal. We could 
not expect the structure or forms of these to be preserved. The 
only cellular plants of the coal measures — species of polyporous 
fungi — have been shown by Mr. Binney to be the thick ganoid 
scales of a fish. 
Parasites having a higher position in the vegetable kingdom 
than cryptogams may have flourished on the trees of the 
carboniferous forests — parasites analogous to the orchids and 
aroids of tropical forests. A confirmation of this opinion may 
be found in the only certain specimen of an angiospermatous 
phanerogam which has been found in the coal measures, and 
which from its resemblance to the inflorescence of some recent 
Aroidese its discoverer Dr. Patterson named Pothocites. 
In examining the principal forms of the Coal Flora we need 
do little more than refer to the ferns. Not only do the fossil 
species obviously belong to this order, blit some of the forms do 
not apparently differ from genera now living. The fructification, 
when it is present, the venation, and the few specimens in which 
the circinnate venation has been preserved, show that in their 
structure and economy the palseozoic species agreed with their 
modern representatives. The chief difficulty that besets this 
study is the almost invariable absence of the fructification, upon 
which the modern classification of the order is chiefly based. 
Brongniart has employed the venation, and in the absence of 
fruit the best characters are to be obtained from it ; but the 
examination of a large series of recent species shows, that many 
forms widely separated systematically, have similar venation. 
The general outline of the frond has also been used for obtain- 
ing specific characteristics, but among living forms a great 
variety in this respect occurs. It is probable that on account 
of errors from the necessarily unsatisfactory materials for classi- 
fication, the number of species has been greatly overestimated. 
