[ ] 

 their young without having one of thefe 

 Stones in their Neft ; but it is to be 

 looked upon as a mere idle Fi6lion, the 

 Experience of many fucceeding Ages 

 beino; far from warrantino- the AfTertion. 

 Thefe Stones are formed of two different 

 Subftances, the one much harder and 

 more compa6l than the other j the Nu- 

 cleus, which is of a fofter Matter than 

 the Surface, (hrinks as it petrifies, thereby 

 leaving a Cavity betw^een the harder Cir- 

 cumference and itfelf, and being of courfe 

 'k)ofe, muft naturally rattle. 



Under this Title are clafTed all the 

 hollow Pebbles ; thofe which particularly 

 bear this Name have another enclofed in 

 the Cavity of them, which may be known 

 by their rattling. In others is very 

 plainly heard a Liquid, which, on open- 

 ing them, is only found to be foul Wa- 

 ter : this Kind is called Enhydros, When 

 they have an earthy Matter inclining to 

 the cryftaliine in them, they take the 

 Name of Gecdes % and when there are in 



one 



