THE PRESEEVATION OP EOZOON. 103 



that wlien decalcified these are most beautifully repre- 

 sented by their casts, Dr. Hunt has proved the filling 

 , mineral to be a silicate of alumina, iron, magnesia 

 md potash, intermediate between serpentine and 

 rlauconite. We have, therefore, ample warrant for 

 idhering to Dr. Hunt^s conclusion that the Lauren- 



FiG. 25. Joint of a Crinoid, having its pores injected with a 



Hydrous Silicate. 



Upper Silurian Limestone, Pole HiU, New Brunswick, Magnified 25 diameters. 



tian serpentine was deposited under conditions similar 

 to those of the modern green-sand. Indeed, indepen- 

 dently of Eozoon, it is impossible that any geologist 

 who has studied the manner in which this mineral 

 is associated with the Laurentian limestones could 

 believe it to have been formed in any other way. Nor 



