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 effects 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 va- 

 rious colours, the scales of fishes Meconites, resembling the poppy 



