On the Zoological characters of formations, with 

 the application of these characters to the detev' 

 mination of some rocks of the Chalk formation. 

 By Alexandre Brongniart, Member of 

 the Royal Academy of Sciences, Sfc. 



(Annales des Mines, 1821.) 

 Read at the Academy of Sciences, Sept. 3, 1821. 



. IN a report that I made to the Academy of Sciences in 

 1819, 1 was led to present a collection of facts I had brought 

 together, in order to draw the attention of naturalists to the 

 remarkable assemblage of circumstances which accompany 

 each kind of rock in very distant countries, and under very 

 different latitudes and meridians. These interesting resem- 

 blances, which had not as yet been offered, at least in so 

 complete and evident a manner, which Avere in a great mea- 

 sure due to observations as yet unpublished, formed but a 

 sketch then too little finished, for publication. 



But I have since then taken up some of the subjects con- 

 tained in this general sketch, and I have endeavoured to de- 

 velope them, and offer proofs sufficient to confirm the results. 



The organic remain that was the cause of these remarks, 

 was a trilobite sent from North America by M. Ilosach : 

 tliis remain of an animal of the crustaceous class, presented 

 a species and position resembling those observed in Europe. 



To the use that may be made of organic remains in the 

 determination of formations I now return, by applying it to 

 another class of rock, to one which forms part of our coun- 

 try, but which, more ancient than that which forms the 



