16 
the species of shells thus changed, and the places where they were 
found. 
That substances, which had undergone this extraordinary change, 
existed upwards of two thousand years since, in quantities so con- 
siderable as to have excited the attention of the Grecian philoso- 
phers, is therefore very evident. So prodigious and so extensive 
were the etfects they noticed, that we find almost all of them con- 
tending for the eternal duration of the world ; finding it difficult to 
conceive any period of time, in which changes, so vast and extraor- 
dinary, could be accomplished. 
The Romans, more disposed to cultivate the fine arts, and to en- 
courage works of genius and imagination, did not pursue the study 
of natural history with much avidity. Excepting in the works of 
Pliny, but little of originality is discovered in the writings of their 
natural historians. They appear to have contented themselves with 
merely preserving the discoveries of the Greeks ; neither seeking to 
add to the stock of facts, which had been already collected ; nor, by 
their researches to ascertain, what degree of reliance might be placed 
on the various histories of nature which had been transmitted them. 
In the works of Pliny, who wrote near 1800 years ago ; and in 
that part of his writings, which probably are considerably indebted 
to the lost work of Theophrastus, who wrote about 300 years before 
Christ, we find mention is made of several substances, which future 
observation has taught must have undergone the process of petri- 
faction. Among the most remarkable of those of which he speaks, 
is the Bucardia, like to an ox’s heart — Brontia, resembling the head 
of a tortoise, supposed to fall in thunder-storms — Glossopetra, like 
to a human tongue ; which does not grow in the earth, but falls 
from heaven whilst the moon is in its wane — Hammites, like the 
spawn of fishes — The Horn of Ammon, possessing, with a golden co- 
lour, the figure of a ram’s horn — Lepidotes, which imitates, in various 
colours, the scales of fishes — Meconites, resembling the poppy — 
