ORYCTOLOGY. 
of tlie vegetable kingdom shall be the first 
subjects of our inquiry. 
The parts of vegetables confined in sub- 
terranean situations sutfer, according to cir- 
cumstances, either a complete resolution of 
composition, the lighter parts becoming vo- 
latilized, whilst the more fixed remain and 
form the substance which is termed mould 
(humus); or, as is supposed by Mr. Parkin- 
son, it passes through another process, which 
he considers as fermentative, and becomes bi- 
tuminous. Wood, thus changed, is called lig- 
num fossile bituminosum, surturbrand, and 
Bovey coal. By the extension of this pro- 
cess, the same author supposed, that the sub- 
stances termed bitumens, (naphtha, petrole- 
um, and asphaltum), are formed. To the same 
process he also attributes tlie formation of 
amber, of wliich however no proof appears. 
That jet, cannel coal, and the common coal 
employed in domestic uses, have had a ve- 
getable origin, is rendered highly probable, 
from the frequency with which they manifest 
the impressions of various vegetable bo- 
dies. 
Thus, perhaps, the formation of the bitumi- 
nous fossils may be satisfactorily explained ; 
but by far the greater ’number of vegetable 
fossils, are of a lapideous nature, and neces- 
sarily owe their formation to very different 
processes; which the same author supposes 
are, in general, preceded by the process by 
which bitumen is formed. Many bodies 
which are evidently of vegetable origin 
may be now found existing in a lapideous, 
either calcareous or silicious, state ; and 
many others are found possessing certain 
marks of the presence of some metallic sub- 
stance. 
To explain these formations, various opi- 
nions have been formed. Some have sup- 
posed the injection of the impregnating 
matter, in a state of fluidity, by ignition ; 
whilst others have imagined the gradual ab- 
straction of the original particles of the 
body, and the regular deposition of tlie im- 
pregnating particles in the spaces which 
have just been left by the original matter. 
Mr. Parkinson, who does not admit of this 
substitution, attributes the formation of tliis 
description of fossils to the impregnation of 
vegetable substances, which have undergone 
different degrees of bituminization, with 
water, holding the earths or the metals in 
solution. Thus with lime is formed the 
calcareous wood or wood-marble of Ox- 
fordshire and Dorsetshire, of Piedmont and 
of Bohemia ; with silex is formed the cal- 
cedonified, agatified, and jasperified wood 
(Holzstein); and with tlie addition of alu. 
mine, &c. the fossil woods which now par- 
take of the nature of pitch-stone, and wax- 
opal (Holzopal). In other situations, me- 
tallic impregnations occur; as in such 
woods as are umpregnated with the pyrites 
of iron, so frequently found in our islands ; 
and the beautiful woods of Siberia, con- 
taining the hydrate and carbonate of cop- 
per. ' 
Various parts of trees and plants (phyto- 
lithi) are found in a mineralized state. Not 
only fossil wood (lithoxylon), as has been 
just noticed, but the leaves (lithopylla or 
lithobiblia), and fruits (carpolithi) of dif- 
ferent trees or plants are thus found. Of 
the woods, several, from their form and 
texture, have been supposed to have been 
originally oak, willow, and such trees as 
now exist in a recent state ; whilst others 
differ, in both these respects, from any spe- 
cies of wood which is now known. 
The impressions of the stalks and leaves of 
plants are very frequently found in many 
parts of the world, in lofty mountains, as 
well as at a considerable depth below the 
surface ; and not only the impressions, but 
the substance itself of different vegetables 
are also thus found ; but in no situation 
more frequent fhan in the neighbourhood of 
coal mines. 
In general these vegetable remains aie 
found deposited in lamina, in the schistose 
strata which accompany the coal ; but the 
most perfect remains are commonly found 
in roundish nodular masses of ferruginous 
clay, which abound in the strata accompa- 
nying the coal. These are commonly 
termed catsheads by the workers of the 
coal mines, and contain pieces of fern, &c. 
very few, indeed, of which are found to 
agree with any known recent plants. One 
of these plants, preserved in coal slate, 
is shewn, Plate I. Oryctology, fig. i. 
The vegetable remains in these fossils ap- 
pear to confirm the opinion above men- 
tioned, of the bituminization of fossil vege- 
tables ; since these leaves are completely 
changed into a bituminous substance. 
The remains of fruits are, perhaps, no 
where found so abundantly as in the Isle of 
Sheppey, where they are dug up in great 
variety; very few, however, being found 
which agree with any known recent fiuits. 
Where any resemblance appears, it is with 
fiuits which only grow in the warm Asiatic 
regions. Plate I. fig. 2, represents a fossil 
fruit which was found in the cliff of Shep- 
pey. 
Fossil roqts of plants of trees are very 
rarely found; a circumstance not very easily 
