﻿Animal Nature of Eozobn Canadense. 63 



connection with that discovery, and with recent objections 

 to the organic nature of Eozoon. 



Dolomite or magnesian limestone is a not infrequent 

 associate of Palaeozoic fossiliferous limestones ; and I have 

 remarked in previous papers on the similarity of the mode 

 of occurrence of silicified Stromatopora? in the great 

 dolomite of the Niagara formation with that of Eozoon in 

 the Grenville Limestone, in which dolomite occurs in 

 beds, in thin layers, and in disseminated crystals, in a 

 manner to show that it was an original constituent of the 

 deposit. Dolomite is also one of the most common 

 minerals filling the cavities of Eozoon, and especially the 

 finer tubuli. The mode of its occurrence on the small 

 scale may be seen in the following description of a section 

 of a portion of a bed of limestone from Cote St. Pierre, 

 examined under a lens, after being treated with dilute 

 acid. The specimen comprised about six inches of the 

 thickness of the bed : — 



Crystalline limestone with crystals of dolomite, consti- 

 tuting about one half (fragments of Eozoon in calcite 

 portion).^ 



More finely crystalline limestone, with rounded granules 

 of serpentine, some of them apparently moulded 

 in cavities of Archseospherinse, or of chamberlets 

 of Eozoon. 



Limestone with dolomite as above, but including a thin 

 layer of limestone with granules of serpentine. 



Limestone and dolomite, with a few grains of serpentine 

 and fragments of Eozoon. 



Crystalline dolomite with a few fragments of Eozoon, as 

 limestone, with canals in dolomite. 



Limestone with fragments of Eozoon, granules of serpen- 

 tine, and groups of chamberlets filled with serpentine. 



We have thus a bed of limestone in which dolomitic 



1 Distinguished by their fine granular texture and canal- systems. 



