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and the subsequent process of their petrification must 

 have been the result of an operation as rapid in its 

 progress as incomprehensible in its nature : for, sup- 

 posing the substance, of which the rocks that contain 

 petrified fishes, are composed, were to be precipitated 

 or deposited from any menstruum, according to our 

 ideas of that process, it is both morally and physically 

 impossible for any dead animal substance to retain all 

 its natural characters, a sufficient length of time to ad- 

 mit the lapidification of the rocks and the animal sub- 

 stance itself, without a material change or alteration, 

 except, at a temperature but little short of the freezing 

 point. 



Almost all dead animal bodies when entire, and par- 

 ticularly fishes, will remain but a very little time in fresh 

 water, without being subjected to three material chan- 

 ges ; neither of which are discoverable, that I know of, 

 in petrified fishes. 



In the first place, they all become more or less 

 bloated, a mark which I have never seen mentioned as 

 it respects fossil fish. This, however, would depend 

 on the degree of temperature of the medium to which 

 they may be subjected. 



Sdly. They very soon change in colour, and become 

 of a pale white ; the eyes sink and assume a livid ap- 

 pearance. 



3dly. Every part except the scales in fishes soon 

 discovers a progressive state of dissolution, which 

 tends rapidly to mutilate or destroy the characters 



