234 RELICS OF PRIMEVAL LIFE 



proposed. The first is that of Professors King and 

 Rowney, who regard the chambers and canals filled 

 with serpentine as arising from the erosion or partial 

 dissolving away of serpentine and its replacement 

 by calcite. The objections to this are conclusive. 

 It does not explain the fine tubulation, which has 

 to be separately accounted for by confounding it, 

 contrary to the observed facts, with the veins of 

 fibrous serpentine which actually pass through 

 cracks in the fossil. Such replacement is in the 

 highest degree unlikely on chemical grounds, and 

 there is no evidence of it in the numerous serpen- 

 tine grains, nodules, and bands in the Laurentian 

 limestones. On the other hand, the opposite re- 

 placement, that of limestone by serpentine, seems 

 to have occurred. The mechanical difficulties in 

 accounting for the delicate canals on this theory are 

 also insurmountable. Finally, it does not account 

 for the specimens preserved in pyroxene and other 

 silicates, and in dolomite and calcite. A second 

 mode of accounting for the facts is that the Eozoon 

 forms are merely peculiar concretions. But this 

 fails to account for their great difference from the 

 other serpentine concretions in the same beds, and 

 for their regularity of plan and the delicacy of their 



