THE PRESERVATION OF EOZOON. 101 



been handed down to our time in a state of preserva- 

 tion comparable, as Dr. Carpenter states, to that of 

 le best preserved fossil Foraminifera from the more 

 jcent formations that have come under his observa- 

 [on in the course of all his long experience. 

 Let us now look more minutely at the nature of 

 le typical specimens of Eozoon as originally observed 

 id described, and then turn to those preserved in 

 iher ways, or more or less destroyed and defaced, 

 faking a polished specimen from Petite Nation, like 

 fehat delineated in Plate Y., we find the shell repre- 

 sented by white limestone, and the chambers by light 

 green serpentine. By acting on the surface with a 

 dilute acid we etch out the calcareous part, leaving 

 a cast in serpentine of the cavities occupied by the soft 

 parts ; and when this is done in polished slices these 

 may be made to print their own characters on paper, 

 as has actually been done in the case of Plate Y., which 

 is an electrotype taken from an actual specimen, and 

 shows both the laminated and acervuline parts of 

 the fossil. If the process of decalcification has been 

 carefully executed, we find in the excavated spaces 

 delicate ramifying processes of opaque serpentine or 

 transparent dolomite, which were originally imbedded 

 in the calcareous substance, and which are often of 

 extreme fineness and complexity. (Plate YI. and fig. 

 10.) These are casts of the canals which traversed 

 the shell when still inhabited by the animal. In some 

 well preserved specimens we find the original cell- 

 wall represented by a delicate white film, which under 



