1865.] 



DAWSON — STRUCTURE OF EOZOON. 



101 



Under the microscope the resemblance to Stromatopora is seen 

 to be in general form merely, and no trace appears of the radiating 

 cells characteristic of that genus. The laminae of serpentine and 

 pyroxene present no organic structure, and the latter mineral is 

 highly crystalline. The laminae of carbonate of lime, on the con- 

 trary, retain distinct traces of structures which cannot be of a 

 crystalline or concretionary character. They constitute parallel or 

 concentric partitions of variable thickness, enclosing flattened spaces 

 or chambers, frequently crossed by transverse plates or septa, in 

 some places so numerous as to give a vesicular appearance, in others 



3. Nature-printed section of a specimen of Eozobn Canadense from 

 Petite Nation Seigniory.* 



[* The replacing mineral in this specimen being serpentine, the cal- 

 careous septa were dissolved from the polished surface by the action of 

 an acid, and the fine material replacing the tubuli having been removed by 

 the aid of a brush, a wax mould of the etched surface furnished the 

 electrotype cast from which the above figure is printed. The lights 

 thus represent the calcareous skeleton, and the shaded portion a thick 

 mass of serpentine,which is distinguishable from a contiguous thin stratum 

 of the same mineral, that seems to form the base of the Eozoon. The 

 gradual passage from the wide chambers and thick septa to the nar- 



