337 
ON THE STRUCTURE AND AFFINITIES OF LEPIDODEN- 
DRON AND CALAMITES. 
By WILLIAM CARRUTHERS, F.L.S., BOTANICAL DEPARTMENT, 
BRITISH Museum. 
(Pirates LV., LVI.) 
The imperfect knowledge we have of fossil plants is the result of 
the fragmentary condition in which they occur. The deciduous leaves, 
ripe fruits, or broken branches that fell into streams, and were carried 
to sea or lake, had so many dangers to encounter, that only a very 
few of them ever reached the usual deposit where they would be pre- 
served, and these few in such a decayed and fragmentary condition 
that it is often impossible to do more than make the most vague guesses 
at the nature of the vegetation to which they belonged. The occur- 
rence of vegetable remains on the site where they grew, is extremely 
rare in all the formations which form the crust of the earth, except in 
the coal-measures. . The plants of this period might therefore be ex- 
pected to be well known, especially as the beds containing vegetable 
remains, of carboniferous age, have been more exposed, because of 
their economic value, than those of any, or indeed of all the other 
formations put together. The peculiar nature of the vegetation, and 
perhaps the extreme humidity of the atmosphere, and the swampy loca- 
lities in which the plants grew, have made the superabundant mass of 
vegetable remains as great a mystery as the scanty and fragmentary 
fossil plants of other periods. Except in the thin films of charcoal 
which occur in most coals, traces of structure are scarcely to be found 
in the coal itself, so thoroughly has the vegetable matter been con- 
verted into amorphous pulp before mineralization took place, or so com- 
shales, they are so fragmentary, that it is difficult to determine the 
various portions that belong to the same plant. The root is rarely 
connected with the stem, the stem with the branches, or the branches 
with the leaves or the fruit. As a result, all these parts have been 
often referred to different genera, and have received different names. 
With additional observations, the means are, however, occasionally 
which enable us to reduce some of these genera, the 
turning up, 
Z 
VOL. IV. [NOVEMBER 1, 1866.] 
