OF FOSSILS. 217 



from the external appearance, and obvious to all, 

 we were able to obtain the object ofourre- 

 fearch, no method could certainly be more fim- 

 ple ; tor, with the ailiftance of our fenies only, 

 we might liiipcnic with the tedious precedes of 

 experiments : Jiut we have already difcovercd 

 the fallacy of relying on many of thefe marks, 

 even the mod principal, as they are liable to be 

 aiicctcd by various circumilunces of iltuation, 

 and diveriiiicd \vitliout end, ( xviii.). It may 

 be proper, therefore, to enter a little more mi- 

 nutely into the coniideration of this queflion. 



xxiv. Uncertain and deceitful Size of FofftJs. 



IN no criteria can we poflibly have lefs faith 

 than in that of magnitude ; and \ve cannot fuifi* 

 ciently exprefs our aftoiiifhment at the violence 

 ofiercd to nature, when a larger piece of ftone, 

 referred to its proper genus, if reduced to a pow- 

 de, is net only exiled to fome other, but is not 

 even permitted to remain under the fame clafs. 



xxv. And Colour. 



Tun vulgar proverb, that cautions us againft 

 belief in colour, in not inapplicable to ory do- 

 logy. It is well known, that there arc icvcn 

 primitive colours; and, in order that a body 

 appear coloured, it is rccjuiiitc that fonv. parti- 

 cular 



