FOSSIL REMAINS OF INVERTEBRATED 

 ANIMALS. 



The remains of invertebrated animals are so excessively nume- 

 rous in species — we should say, perhaps, innumerable — that it 

 cannot be expected that we should enter into minute details 

 concerning them^ or pretend to present our readers with any 

 thing like a complete enumeration of them. We must content 

 ourselves, therefore, with some general observations on the most 

 interesting points of the subject^ and a notice of the localities, 

 &c. of the most remarkable genera, and such as are of most fre- 

 quent occurrence. 



We cannot commence this department of our labours more 

 appropriately, than by some remarks on the nature, circum- 

 stances, and varieties of petrifactions in general. 



It has been asserted that the petrifaction of organized bodies 

 was a mechanical operation, in which the stony matter replaced, 

 molecule by molecule, the substance of those bodies. But 

 this supposition is far from being clearly demonstrated. Some 

 bodies, in passing to this state, have preserved both their ex- 

 ternal and internal forms : others have preserved the first only; 

 and there are more, such as certain of the fungiform polyparia, 

 in which the part approaching to the edge has preserved its 

 original contexture ; while that which is found towards the 

 middle is only a confused petrifaction, or crystallization, in 

 which no organization can be discovered. 



Some ancient authors, who have written on oryctography, 

 would consent to class among petrifactions those only whose 

 analogues were already known : the remainder of such produc- 

 tions was considered as nothing but figured stones — the work 

 of simple chance. At the present day, however, there are none 

 who devote their attention to this very interesting department 

 of natural history who entertain the slightest doubt that the 

 bodies, which are found in the strata of the globe, have belonged 



